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Some more "by 2080" stuff, albeit less cheery.

For much of my adult life, quite possibly all of it - and I'm not young - I've been hearing this "by 2000" or "by 2020" or "by 2030" or "by 2050" happy talk, usually with a superoptimistic "100% renewable" stuff.

As of 2017, or "by 2017" the entire wind and solar portion of so called "renewable energy" amounted to less than 2% of world energy demand.

2018 Edition of the World Energy Outlook Table 1.1 Page 38

The result is that we are seeing concentrations of the dangerous fossil fuel waste CO2 in the atmosphere is approaching 412 ppm, with no end in sight.

Here's a somewhat more dire prediction, a "by 2080" prediction of what the betting of the atmosphere on so called "renewable energy" will produce if it continues as it has for the last half a century of wild cheering for it, first in theory and then, regrettably, in practice:

Nearly one billion people could face “their first exposure” to a host of mosquito-borne diseases by 2080

The full original paper to which this news item from Carbon Brief, to which I subscribe (and you can too, easily and for free) is opened sourced and is here: Global expansion and redistribution of Aedes-borne virus transmission risk with climate change (Ryan et al PLOS Neglected Tropical Diseases 2019)

I trust you're having a pleasant evening.

Impregnating magnesium carbonate with polyethyleneimine to capture carbon dioxide.

The paper I'll discuss in this thread is this one: Impregnation of PEI in Novel Porous MgCO3 for Carbon Dioxide Capture from Flue Gas (Xiao et al, Ind. Eng. Chem. Res., 2019, 58 (12), pp 4979–4987)

Despite the title of the paper I am discussing herein, I personally believe that the concept of the "flue" should be phased out as rapidly as possible. "Flues" are waste dumping devices; in almost every case, they are the equivalent of pipes dumping raw sewage into rivers and other bodies of water. Flues dump waste into what has become humanity's favorite waste dump, it's planetary atmosphere, which is rapidly being destroyed by indifference and/or the inexplicable popular enthusiasm for technologies which don't work very well; here, as usual, I'm referring to the multi-trillion dollar investment in wind and solar energy which has done nothing, absolutely nothing, to arrest the acceleration of climate change. We are now at around 412 ppm of CO2 in the atmosphere; at the end of March, 1998, we were at 369 ppm.

Elon Musk. Tesla electric car. Megawatts Solar. Megawatt wind.

We are oblivious.

As we are oblivious, it will fall to future generations, from the immediate through the end of human time, to clean up our mess, and do so after we have robbed them of important resources. The clean up of the mess we've made of the planetary atmosphere, is an unimaginable engineering challenge which will require the generation of vast amounts of energy while using zero fossil fuels, almost all of which will have been oxidized and dumped in the atmosphere as even more waste to clean up.

After much study, I consider that this task is just over the line of feasibility; it might be accomplished, but only with a massive concerted effort of all of humanity, such a concerted effort being the most improbable feature of the effort among all features, included the technical features.. We are making 1930's fascism look like small change, given the consequences of the environmental results of present day fascism (albeit disguised as "democracy." )

While I oppose flues, I do consider that combustion ironically represents a part of the path to removing carbon dioxide waste from the atmosphere, at least in the case where the carbon dioxide is generated in an atmosphere of pure oxygen (this generated by nuclear heat) with the combustion of waste biomass. Under these circumstances a pure stream of carbon oxides (monoxide and dioxide) are generated; where steam is present, hydrogen and carbon dioxide, a form of "syn gas" that can essentially replace all materials now obtained from dangerous petroleum, can be generated.) Similarly, "dry reforming" heating biomass to high temperatures under an atmosphere of pure carbon dioxide, can generate carbon monoxide, which can be disproportionated into various allotropes of carbon and more carbon dioxide.

For various reasons, including the increase of energy efficiency under certain rather obscure but real circumstances, carbon capture technologies are of interest, even if the idea of "carbon sequestration" in waste dumps is a Quixotic and useless exercise that will not work. Hence my interest in this paper.

My comments aside, the paper begins with a genuflection to the idea of "carbon capture & storage" "CCS" as opposed to what I believe to be essential in order to give these processes any remote chance of being useful, sustainable and economic, "carbon capture and utilization" "CCU." It also refers, as it comes from a Chinese institution, to coal, a fuel I oppose along with the allegedly "green" dangerous fossil fuel, dangerous natural gas, and of course, petroleum.

From the introduction:

Global warming and other consequential environmental problems resulting from the greenhouse effect have received a great deal of attention in recent years. Since CO2 is the major contributor to greenhouse gases, it is particularly important and urgent to reduce the amount of CO2 emitted into the atmosphere due to the utilization of fossil fuels.1 Considered to be a critical solution to global CO2 emission reduction, CO2 capture and storage (CCS) technology has been given an urgent requirement for its own development.2 Among the various CCS technologies, the chemical absorption using aqueous solutions of amines, such as monoethanolamine (MEA), methyldiethanolamine (MDEA), and diethanolamine (DEA), is the most mature and well-established one for CO2 capture.3,4 However, this process presents major drawbacks, such as high operating costs, evaporation of amine solution, and equipment corrosion,5 which lowered the production efficiency of coal-fired power plants by 10−12%.6 Thus, there is a growing demand on new energy-efficient CO2 capture techniques for CCS applications. The adsorption process with the use of solid adsorbents has been developed to overcome these drawbacks in chemical absorption and showed the advantages of high product purity, low energy consumption, low toxicity, and ease of adsorption and regeneration,7−9 which displayed a broad application prospect in adsorptive separation of CO2 from flue gas.10,11 During recent years, numerous studies have reported that the CO2 capture capacity of porous solid adsorbents could be greatly enhanced by amine modification.12,13 These amine-modified solid adsorbents can be simply obtained by physically impregnating the porous supports with amine,14 which showed a higher CO2 capture capacity and lower cost compared to the grafting methods.15 An excellent amine-modified adsorbent should have unobstructed pore structure for CO2 transfer16 and a high capture capacity of CO2...

Many of the well known examples of solid phased carbon dioxide capture agents are challenging to synthesize on an industrial scale, a point the authors make referring to silica base absorbents, including the well known MCM-41:

Although amine-modified mesoporous silica-based materials exhibit excellent CO2 adsorption properties, the preparation of mesoporous silica is not cost-effective due to the use of expensive silica sources and surfactants in the synthesis, leading to difficulties with large scale manufacturing.32 Besides, it is an essential step to remove the organic surfactants after the synthesis of silica materials, which indeed involves the use of high temperature and chemicals that could increase the cost and the environmental burden.33 Therefore, the easily synthesized and environmentally friendly porous materials with superior performance and desired economics urgently need to be developed as the support of amine-modified adsorbents. Moreover, in addition to N2 and CO2, the flue gas also contains water vapor, SO2, and NOX, which may affect the performance of amine-modified adsorbents during CO2 capture.

What the authors propose is to synthesize a mesoporous form of magnesium carbonate, having the interesting property that its preparation is a case of CCU, inasmuch as the synthesis utilizes carbon dioxide as a reactant:

2.2. Synthesis of Adsorbents. The porous MgCO3 was prepared as the procedure reported previously.34 Briefly, MgO was mixed with methanol, after stirring under 3 bar CO2 pressure at 50 °C for 3 h, the mixture reacted under 1 bar CO2 pressure at 25 °C, followed by drying at 70 °C for 3 days, the dried product was calcined at 250 °C for 3 h with a 3 h ramp time. On the basis of this method, in order to select the best support, the following 5 samples (M1 to M5) were synthesized under different experimental conditions, which are shown in Table 1, respectively.

Methanol is readily available from syn gas. Table 1 lists synthesis conditions. M4, which is the most discussed porous MgCO3 form is prepared with the methanol containing 33% toluene, toluene being a product of the dangerous petroleum industry which is, albeit not industrially, conceivable to obtain from certain forms of biomass, for example by the reaction of butadiene (from cellulose derived furan) or pentadiene (from methyl furan) with ethylene (from syn gas) or propylene (also from syn gas). M4 is prepared by stirring MgO in this solvent under a CO2 atmosphere for 4 days at room temperature.

Further aspects of the process are described, using ethanol, also available from syn gas, and, of course, albeit as questionably as is the case with other so called "renewable energy" schemes, from grain:

PEI-modified MgCO3 adsorbents were prepared via a wet impregnation method.35 The desired amount of PEI dissolved uniformly in ethanol was added to the sufficiently dried MgCO3. The resulting slurry was stirred and refluxed at 80 °C for 2 h. After completely evaporating the ethanol at 80 °C, the sample was dried at 100 °C for 2 h in an oven. The obtained adsorbent was denoted as xP-M, where x (x = 10, 20, 30) indicated the mass percentage of PEI. The synthetic process of porous MgCO3 and PEI-modified MgCO3 adsorbents is illustrated schematically in Figure 1.

The "x" in "xPM" carries through the paper, for example 20P-M, is 20% PEI and 80% MgCO3.

Beginning with Figure 1, let's now just look at the pictures, a useful way to get a feel for a full paper before reading it in detail.

The caption:

Figure 1. A schematic diagram of the synthesis of porous MgCO3 and the impregnation process of PEI.

The caption:

The testing apparatus for measuring its performance as an absorbent:

The caption:

Figure 2. Diagram of experimental apparatus for CO2 adsorption.

Note that the authors are imagining this material to capture carbon dioxide from the flue gas from the combustion of dangerous coal. In contracts to the combustion of biomass in a pure oxygen atmosphere, the air fueled combustion of coal will contain considerable amounts of nitrogen. Hence the effect of nitrogen is considered important by the authors:

The caption:

Figure 3. N2 adsorption/desorption isotherms (a) and pore size distribution curves (b) of the prepared groups of MgCO3

It seems that the PEI loadings have a fairly large effect on gas availability in the pores, related to the extent to which pores in the magnesium carbonate are obstructed by the polymer.

The caption:

Figure 4. N2 adsorption/desorption isotherms (a) and pore size distribution curves (b) of M4 and adsorbents with different PEI loadings.

The caption:

Figure 5. FTIR spectra of M4 and adsorbents with different PEI loadings.

The caption:

Figure 6. SEM images of M4 (a), and adsorbents with different PEI loadings:10P-M (b), 20P-M (c), and 30P-M (d).

"Breakthrough" below refers to the point at which CO2 is detected after the flow has passed over the absorbent.

The caption:

Figure 7. Breakthrough curves of CO2 of M4 and adsorbents with different PEI loadings at 25 °C (a), 40 °C (b), 60 °C (c), and 75 °C (d).

20P-M can capture carbon dioxide at fairly high temperatures:

The caption:

Figure 8. Effect of adsorption temperature on the CO2 capture
capacities of M4 and adsorbents with different PEI loadings.

The effect of trace gases on the absorption:

The caption:

Figure 9. Effects of H2O, NO, and SO2 on the breakthrough curves (a), (c), (e), and CO2 capture capacity (b),(d), and (f) of 20P-M at 75 °C.

It is important to note here that even in pure oxygen, combusted biomass will contain limited amounts of these impurities because biomass will contain nitrogen (in proteins and nucleic acids) and sulfur, (from the amino acids cysteine and methionine, and molecules for which they are biological precursors.

The material shows excellent recyclability when the carbon dioxide is removed at approximately 100 C.

The caption:

Figure 10. CO2 capture capacity of 20P-M during 10 cycles of CO2 adsorption/desorption in dry and 10 vol % H2O contained flue gas.

An excerpt from the conclusion of the paper:

A variety of MgCO3 with different porous structures were successfully synthesized and characterized. The synthesis of MgCO3 was based on a facile and template-free method and utilized CO2 as reactant, allowing the porous MgCO3 to be new and promising CO2-storage materials. Meanwhile, the synthesis strategy developed is also beneficial to the potential utilization of CO2. Among those as-prepared MgCO3 materials, M4 with the optimal morphology was selected as support for CO2 adsorbent. A series of adsorbents with different PEI loadings were prepared by effective impregnation while the microstructure of the adsorbents was well maintained afterward. The capacity of CO2 capture in PEI-modified adsorbents was significantly increased, particularly for the adsorbent with 20% PEI loading (4 times higher than the one without PEI at 75 °C, up to 1.07 mmol/g). At low temperature (25 and 40 °C), because of the sterically hindered effect, adsorbents with relatively low PEI loading performed better than the highly loaded ones. On the contrary, the high PEIloaded adsorbents were advantageous at higher temperature (60 and 75 °C) where the diffusion resistance was reduced.

Whether we know it or not, whether we spend our time obliviously picking lint out of our navels glibly waxing enthusiastic for Elon Musk's stupid car and/or the endless series of "renewable energy breakthroughs" decade after decade, this while these "breakthroughs" fail to even slow the rise in the use of dangerous fossil fuels and the contamination of the atmosphere, or whether we recognize the need to change our attitudes and face the true magnitude of the problem, we are in very, very, very bad shape with respect to the environment on which all life depends.

Papers like this one allow, nevertheless, for a sliver of hope.

I trust you're having a pleasant Sunday afternoon.

South Korea accepts geothermal plant probably caused destructive quake.

I came across this news item in a recent issue of Nature.

Bricks and debris from damaged buildings lie on the ground in front of a damaged car in Pohang, South Korea
A 2017 earthquake in Pohang, South Korea has been linked to a geothermal plant.Credit: Yonhap/EPA-EFE/Shutterstock

A South Korean government panel has concluded that a magnitude-5.4 earthquake that struck the city of Pohang on 15 November 2017 was probably caused by an experimental geothermal power plant. The panel was convened under presidential orders and released its findings on 20 March.

Unlike conventional geothermal plants, which extract energy directly from hot underground water or rock, the Pohang power plant injected fluid at high pressure into the ground to fracture the rock and release heat — a technology known as an enhanced geothermal system. This pressure caused small earthquakes that affected nearby faults, and eventually triggered the bigger 2017 quake, the panel found.

The quake was the nation’s second strongest and its most destructive on modern record — it injured 135 people and caused an estimated 300 billion won (US$290 million) in damage...

...Earthquakes have been linked to geothermal power plant in other parts of the world. But the Pohang quake is by far the strongest ever tied to this kind of plant — 1,000 times mightier than a magnitude-3.4 quake triggered by a plant in Basel, Switzerland, in 2006.

The full brief news item seems to be open sourced, since I didn't need to log in to read it:

Nature News 22Mar19.

Have a pleasant Sunday.

Refractory Ablative Heat Shields for Spacecraft: A Path to Addressing Climate Change?

The paper I will discuss in this post is this one: Zirconium-Doped Hybrid Composite Systems for Ultrahigh-Temperature Oxidation Applications: A Review (Giridhar Gudivada and Balasubramanian Kandasubramanian, Ind. Eng. Chem. Res., 2019, 58 (12), pp 4711–4731)

This paper itself is not about climate change, and the reason I am posting it here in the E&E section, rather than the Science group, where it may be equally appropriate if not more appropriate, is solely based on my own speculations, speculations connected with some insight into how superalloy turbines, wherein the surfaces are protected by thermal barrier coatings, work. These types of turbines are generally utilized in dangerous fossil fuel combustion systems such as combined cycle gas - and far more rarely in combined cycle integrated gasification coal plants - and in dangerous petroleum fueled jet aircraft, but they it is clear that they might well be adapted for use in cleaner and safer nuclear systems. One feasible avenue - not the only avenue, but certainly one likely to be important - is the high temperature, high pressure reformation of biomass. Some, but not all, of the energy invested in reforming the biomass can be recovered by allowing the resultant gases, likely to be a mixture of steam, hydrogen, and carbon dioxide (or, if the water has been consumed, carbon monoxide) to expand against a turbine. The hydrogen/carbon oxide mixtures (syn gas) will then be available to displace all of the current uses for dangerous fossil fuels, including those that represent sequestration in products. In this case, particularly in the case of extreme temperatures that are ideal for many reasons of efficiency, the velocity and temperature of the gases, particularly at critical points like nozzles, are likely to approximate those found on the surfaces of vehicles experiencing re-entry or launch at supersonic speeds.

Thus, the relevance of this materials science paper to climate change can be established.

The introduction to this review indicates what the subject is really about, which is not turbines, but high speed aircraft and space craft:

Ablative materials are degenerative composite systems which, by design, are processed to degrade at projected rates when exposed to high aerodynamic heat rates (∼10^5 BTU/ft^2) at high temperatures (∼8000 °C). Ablative materials have diverse applications1−5 in the fields of aerospace as a protective layer for leading edges6 of the control surface, in medicine for curing various diseases in form of ablating lasers and in space technology as thermal protecting systems at hyperthermal7−9 environments. In the field of medicine, ablation2 phenomenon is used to cure tumors and treat irregularities in heart pulse rates; by focusing high dosages of energy over a small volume, as in the case of ablative radiography or catheter ablation for atrial fibrillation; however, in the case of aerospace technology, heat energy is insolated upon a larger surface that is to be considered. The term “ablation” in medical terminology implies the complete removal of material from the host system, as in the case of tumors and in the case of atrial fibrillation, the paths of unnecessary impulses are cut down, whereas, for the field aerospace technology, only a part of the system is necessarily required to ablate at known uniform rates under stable operating conditions. A technical understanding of the phenomenon ablation, as early as 1983, states that,
“Ablation is a complex energy dissipative process whereby a material undergoes combined thermal, chemical, and mechanical degradation accompanied by a physical change or removal of surface material”.10
The degradation process has been a keen interest among the scientific community for many years and has evolved many techniques to converge upon a common idea, i.e., how an ablative material functions under severe aerodynamic conditions. Recently, the multiphase modified matrix technology, unlike simple single-phase matrix systems of two classes mentioned in the next section has offered a platform for yielding knowledge investment from a multidisciplinary background of science and engineering for design the ablative materials. Therefore, the performance of modern ablatives is tending toward euclidative application of ultrahightemperature ceramics, potentially with zirconium diboride, because of its quick and timely response to the cataclysmic reentry environments as witnessed by the thermokinetic approach and experimental procedures that are discussed in this article.

1.1. Re-entry Vehicle Structures. Re-entry11−14 vehicle structures are marvels of modern engineering that have made human space travel conceivable by guaranteed safe landings, surviving the extreme re-entry conditions that are discussed in the next section...

The main idea of these kinds of systems is two fold: They are designed to dissipate some heat by exploiting the very high heat of vaporization of very high melting (and vaporizing) systems while protecting inner layers from heating beyond their melting points by containing materials that have extremely low thermal conductivity.

One of the best descriptions of this phenomenon is the paper published by the great Princeton University Scientist Emily Carter on the occasion of her induction into the National Academy of Scientists: Atomic-scale insight and design principles for turbine engine thermal barrier coatings from theory (Kristen A. Marino, Berit Hinnemann, and Emily A. Carter, April 5, 2011 108 (14) 5480-5487) The full paper is available open sourced on line, but for convenience I reproduce an excerpt of the introduction here:

Aircraft and power plants share a common source of usable energy: Both employ turbine engines that combust fuel to either propel airplanes or produce electricity. At a time in which efficient use of energy is paramount, improving the efficiency of turbine engines is one means to contribute to this global challenge. Turbine engines operate via the Brayton cycle, which offers lower carbon dioxide emissions and lower cost for power generation than other possible alternatives. Their efficiency can be increased by increasing the inlet temperature...

...However, high-temperature operation, under oxidizing conditions, poses serious demands on the materials...

...Materials must be found that are robust under such harsh operating conditions. Engineers over the past few decades have improved greatly the thermomechanical properties of the metal alloy comprising, e.g., the turbine blades, and have created a multilayer coating for the blades that protects against both heat and corrosion, referred to as a thermal barrier coating (TBC). These materials advances, along with internal component cooling, have been astonishingly successful, allowing the gas temperature to exceed the melting point of the metal alloy from which the engine components are constructed!

The class of multilayered materials largely discussed in the review introduced in this post are ablative, designed to erode (slightly) in use, whereas the layered materials for turbines to which Dr. Carter eludes in her paper, are not. Both papers however discuss the chemistry and material properties of zirconium: Dr. Carter's refers to "YSZ" or yttrium stabilized zirconia, and predicts that a Hf analogue - hafnium is a (relatively rare) cogener of zirconium and titanium - may be superior based on in silico calculations. In the current paper under discussion however, the layered material discusses a material doped with zirconium boride, an extreme refractory.

The paper has a nice graphic showing the classes of refractory layered materials:

The caption:

Figure 1. Classification of materials for the thermal protection system.

Of particular interest are the ultra-high temperature ceramics which are described in the text as follows:

1.3. Ultrahigh-Temperature Ceramics (UHTC) for Ablative Applications. The UHTCs are the ceramics with melting points greater than 2700 °C.1 These materials possess properties like good oxidation resistance, ablation resistance, thermal expansion, and damage tolerance among other characteristic features which are discussed in later sections. The best contender among UHTCs for ablative is ZrB2; nevertheless, there are other ceramics like tantalum carbide (TaC), hafnium-diboride (HfB2), and hafnium carbide (HfC) with melting point temperatures higher than that of ZrB2 but there are other aspects, such as cost, ease of processing, availability, and temperature range of chemical activity (1500− 1800 °C). It is necessary for the ceramic to be used as a matrix modifier while ablation during the re-entry phase that they have to respond to the changes in the environment in the vicinity of the boundary layer.49−53

Technologies based on tantalum, are best avoided, since tantalum is a fairly rare and easily depleted element, and - although it is widely used in cell phones - is a conflict metal. Small amounts of it are synthesized in certain types of nuclear reactors, generally ship borne reactors, in control rods by neutron capture in hafnium, but hafnium, utilized in this fashion because of its high neutron capture cross section is relatively rare, and is found as an impurity in all zirconium ores, from which it must be removed for nuclear applications.

Zirconium ceramics, of which zirconium boride is one example, have extremely high melting points, according to the review, better than 3000°C, however they are said to exhibit poor thermal shock resistance and low fracture toughness and, as is true of many ceramic materials, they are brittle. Thus they, as suggested by Dr. Carter's paper, are utilized as composite materials.

This schematic cartoon, showing how ablative thermal shields work, gives a feel for how the layering works:

The caption:

Figure 3. Representation of the ongoing ablation process.

An issue with layered systems however, is that the properties of the materials must be closely matched, specifically thermal expansion and factors like Young's modulus, or "stiffness."

Some mathematics connected with these considerations are described:

…mathematical evaluation of mechanical properties have been undertaken for fracture at high time rate of thermal loads based on certain assumptions which state that the model (Figure 4) is a two well-bonded plate, which does not consider the interface damage, there is no heat exchange between the UHTC plate and base plate, both the layers geometrically confirm with each other which make calculation easier, finally plate is continuous, isotropic, elastic, and is restricted in the domain of small deformation hypothesis.

The equations for the effective linear expansion in the ceramic layer then are given by eq 1:


where Δx1 is the elongation in the ceramic plate without external restrictions and Δxσ is the value of restricted elongation due to complementary compressive stress at the interface. From the above equation, it is evident that the net elongation of the system when assumed the changes in Young’s modulus (Yc) and Poisson’s ratio (μc) for ceramic material are devoid of temperature changes, could generate an internal stress σ in the ceramic plate plausibly at the interface, which was derived by Li et al.,87 as shown in eq 2:


Considering the above equation with the effects of temperature would be modified to eq 3.

Here, the pressure stress or internal compressive stress has been taken into account by considering Young’s modulus (Y) and the coefficient of thermal expansion (?:


The most effective way to mitigate failure by thermal shock is to increase the critical temperature difference of rupture (CTDR). According to Wang et al., the CTDR increases as the temperature of surroundings increase, up to a certain extent, and then decreases. The governing equation for CTDR by Wang et al.,82 is as shown in eq 4


where h is the heat-transfer coefficient, tS is the thickness of the ceramic plate, and R′ is a constant parameter called as second thermal shock resistance parameter and is given by eq 5:


Note that the physical properties of mechanical interest, such as the Young’s modulus and fracture stress, vary along with temperature as described by eq 6.

where B1, B2, B3, and Bo are material constants and Yo is Young’s modulus at ambient conditions. The fracture stress as a function of temperature is given according to Li et al.,87 as in eq 7. In order to understand the dependence of the fracture stress with temperature, it has to be inferred from the function of Young’s modulus that it is dependent on temperature in a transcendental fashion and so does the fracture strength.

It is mentioned that the term

belongs to a temperature-dependent fracture surface energy term82 and indicates that, as the operating temperature approaches the melting point, the ratio φ has a tendency to unity; as a result, the temperature-dependent fracture stress tends toward theoretical stress, leading to failure. The thermal shock resistance can be increased by incorporating microflaws into the ceramics, like crack, pores, grains, residual stress due to thermal expansion anisotropy, and, as such, eliminating the initial rupture temperature reaching the danger zone of temperature for thermal shock resistance as reported by Kou et al.,88 and Wang et al., for materials such as hafnium diboride and zirconium diboride, respectively, along with mathematical reasoning.82 These microflaws also cause deterioration in mechanical performance, as reported by Wang et al., which is testified by the following equations of fracture mechanics...

There is a lot of similar information in this wonderful review and it will not be possible to cover all of the things covered therein. Regrettably the paper is not open sourced, and must be accessed in a library.

It may be useful though, to look at the pictures.

The fine details of how these materials, for which the above text gives some feel, results in changes to the material as it performs, and in some cases, these changes improve the materials performance.

This cartoon evokes as much:

The caption:

Figure 5. Schematic of ablation cycle of a material

These changes can actually enhance the properties of the material. For example, a zirconium boride carbon composite will become coated with ZrO2 in an oxidizing environment, and enhance temperature resistance, since ZrO2 has well known thermal barrier properties, and, as discussed above, can be modified with yttrium to give the widely used "YSZ" material.

Silicon carbide is a well known and widely used refractory ceramic. When doped with zirconium boride, graphene or graphene oxide can form. The following graphic relates to a consequence of this structural rearrangement, which that the material can be utilized as an oxygen reduction electrode in fuel cells in the presence of platinum dopants, thus showing the further the utility and versatility of these materials. Note that if the carbon involved in the graphene and silicon carbide is obtained by air capture (by any means) the carbon is effectively sequestered.

The caption:

Figure 6. Combined effect of graphene and ZrB2 under the influence of an ionized platinum on oxidation properties at low temperatures.

While not explicitly described as such in this review, the paper from which the graphic immediately above comes can be found in this open sourced paper, which, if interested, the reader can easily access and read merely by clicking on the link below.

Nano Conductive Ceramic Wedged Graphene Composites as Highly Efficient Metal Supports for Oxygen Reduction (Mu et al, Scientific Reports volume 4, Article number: 3968 (2014)

In the case of a re-entry vehicle the temperature driven evolution of the material is evoked by the following cartoon:

The caption:

Figure 7. Illustration of ZrB2–SiC response in a typical re-entry environment.

A more detailed representation:

The caption:

Figure 8. Detailed illustration of highlighted area for the typical response of ZrB2–SiC to re-entry environment.

The addition of additional elements are being evaluated to improve the performance of these materials:

Many scientists have investigated the aforementioned studies and concluded that mechanical alloying with rare-earth elements forms a multilayer protective glass coating, yet each layer may still be multiphase. Tan et al.104 modified ZrB2 with samarium and thulium through two processes: first, chemical doping by CVI technique and second, by dry mixing in a ball mill, followed by compaction in a press. Furthermore, they reported that chemically doped ZrB2 best performs by enhanced surface emissivity, which is an ingenious technique to deal with ablating environment as radiation can transfer 90% of heat. It is required to recollect that the addition of one atom to another effects cation field strength and the addition of transitional metals to ZrB2 due to optimal cation field strength (eq 8), there would be immiscibility, which increases viscosity, as explained by the Einstein−Stokes equation (eq 9) of the melt at oxidation temperatures. As a result, oxygen transport into the material reduces in proportion to the increasing viscosity of the melt. In addition, mechanical mixing has not given many admirable results, when compared to chemically modified ZrB2, as reported by Monteverde et al.105



where C denotes cation field strength, Z denotes valency, r denotes ionic radius, D denotes diffusion rate, K denotes Boltzmann constant, η denotes viscosity, p denotes particle dimension, and T denotes absolute temperature…

…Another innovative idea to form multilayer was reported by Zhang et al.,107 by doping zirconium diboride with tungsten carbide (WC), which lead to the formation of dual glass layer (Figure 10), the top layer was porous and depleted of tungsten oxide and appeared light in complexion, while the bottom layer was rich in WC and appeared dark and dense...

Like zirconium, samarium is a fission product, and thus given the high energy to mass density of nuclear energy even when compared with dangerous fossil fuels, appreciable quantities may be available in the reprocessing of used nuclear fuels, especially when the timing of the reprocessing is utilized to minimize or maximize residual radioactivity for some isotopes in some of these elements. The higher lanthanides beyond europium are not appreciably represented as fission products, for example thulium, although small amounts may be formed in a kind of earthbound aufbau process - the manner in which heavy elements are formed in stars in the s-process - in "breed and burn" nuclear reactors, the kind I personally favor. This would result in the use of fission products with high neutron capture cross sections, as represented by the heaviest lanthanide fission products as neutron shields (and in some cases heat sources to maintain metal coolants in liquid states during shut down) In any case, not all of these strategies result in positive outcomes, and the matter should remain an area of materials science research.

Figure 10:

The caption:

Figure 10. Effect of modifying ZrB2 with WC on the formation of barrier coat.

Overall, these effects are summarized in the following graphic:

The temperature gradient that these materials generally experience is shown in this cartoon:

The caption:

Figure 12. Temperature profile of the ablative material.

There is a nice evocation of the thermodynamics of these systems - thermodynamics being the science most routinely ignored by those "efficiency will save us" and "batteries will save us" types that have lead us to the horror of the dangerous fossil fuel waste carbon dioxide's concentrations being permanently well above 410 ppm (and rapidly rising). The discussion includes some very beautiful and fun differential equations as well as an evocation of the Arrhenius equation, Arrhenius being the guy who told us in the late 19th century that what is happening would happen with respect to climate change:

It has also been mentioned that there is a continuous thermal gradient that exists through the char region, reaction/ pyrolysis zone, and unaffected virgin material (Figure 12). An Arrhenius-type temperature-dependent reaction rate (eq 12) has been mentioned and explained as follows:

A significant work presented by Norman et al., where the temperature distribution was presented as a function of char depth and energy balance (eq 13).

The first term apparently is the rate of heat flow through the nonporous part of the material, calculated from Fourier’s principles for one-dimensional (1-D) heat flow, the second term excludes the conductive heat flow into the trapped gases inside the voids, which could otherwise flow away to the surface with the velocity υs, the fourth term is probably the heat rate exchanged between the hot entrapped gases and elemental material of depth dx, while the gases are expelled out of reaction zone of the material with no effectiveness of heat exchange taken into consideration; finally, the last term has been mentioned by Norman et al.,57 as a result of heat of decomposition. With the above analysis, where, for eq 13, ϵ is fractional void in the solid (for a unit length volume fraction and area fraction do not vary significantly), υs is a relative velocity between the material surface and incoming mass of air, ρs is the density of the material, cps stands for the specific heat of material, cpg represents the specific heat of gases, ṁg is the mass rate of gases, ks is the conductivity of the solid, ΔE is the activation energy of phenolic matrix (11 kcal mol−1), MW is a constant with the value of 10, and, finally, kg denotes the conductivity of gas...

There is then a discussion of the preparation methods of these materials, a subject I personally find interesting because of my interest in printable nuclear reactor cores composed of ultrahigh temperature ceramics represented by actinide nitrides. I just have time for the cartoons.

The caption:

Figure 13. Depiction of the sol–gel process.

The caption:

Figure 15. Schematic of a typical CVI process.

There's a depiction of the test equipment:

The caption:

Figure 16. Schematic of the ablation test.

And a graphic illustrating the over all concepts:

The caption:

Figure 17. Design parameters of an ablative material.

Some phenolic resin chemistry of carbon relative to the building of these materials:

The caption:

Figure 18. Mechanism of coalescence of phenol rings during pyrolysis.

This post is, I'm sure, highly esoteric, even for my posts, many of which fit into the category of "esoteric."

I write them to fix concepts in my mind, and post them on the off chance that there are people interested in the practical scientific and engineering issues of addressing climate change which, trust me, are way beyond anything being discussed politically and popularly. There are scientists working long and hard hours to build the intellectual infrastructure by which we may save what remains to be saved, and any attention they get, improves whatever small chances remain for our planet.

Irrespective of your interest in the practical approaches to addressing and even reversing climate change, and the Herculean engineering tasks they represent, I trust you're having a nice weekend.

Pore Size and Shape & the Release of Radon Gas in Fractured Rocks in the Marcellus Shale Gas Fields.

The paper I'll discuss in this post is this one: Investigating Effects of Pore Size Distribution and Pore Shape on Radon Production in Marcellus Shale Gas Formation (Sondergeld et al, Energy Fuels, 2019, 33 (2), pp 700–707).

Although it garnered very little attention until the late 1930's, other than as a colorant for stained glass and to make orange glazes for ceramic cookware and serving dishes, uranium was of considerable scientific interest, and some commercial interest. Industrially the ore was mined not for the metal itself, but rather for its decay product, radium, which was widely used in luminescent watch and clock dials. (I had one of these when I was a small kid. I thought it was great.) The discovery of radioactivity was also associated with uranium, and it gathered much interest in what was, again up until the late 1930's, when Lise Meitner discovered nuclear fission while interpreting the experimental data from an experiment conducted in the laboratory of Otto Hahn.

It was not recognized until well after the discovery of nuclear fission that uranium is a very common element, about as common as tin. Because uranium has been present on the planet since its formation and is often fixed in ores, it has had time to come into "secular equilibrium" with all of its decay products except for the final product, non-radioactive lead. Except in the ocean, which contains a little under 5 billion tons of uranium, where the chemical distribution of decay products is driven by solubility and is thus subject to fractionation, the products of uranium decay generally remain in the ores, unless the ores are disturbed.

The Marcellus shale, which is a large producer of dangerous natural gas is, in fact, a low grade uranium ore, and throughout its geological history it has contained all of the decay products of uranium.

Here is the decay chart for U-238, which should be fairly familiar to people in high school science classes:

Radon-222 (Rn-222) is a noble gas. Where uranium is found in surface soils, it can accumulate in people's basements, and can represent a significant health hazard, in paticular because it's decay product, highly radioactive polonium-218, can lodge in people's lungs, go through several fast radioactive decays and remain, ultimately, lodged as lead-210, with a half life of 22 years. (I have measurable radon in my basement, and probably have a few radioactive atoms in my lungs.)

The half-life of uranium-238 is approximately equal to the age of the earth, about 4.5 billion years. There is so much uranium on the surface and subsurface of the Earth that no technology can ever eliminate it.

Here, for completeness, is the decay chart for U-235, which is also found in natural uranium, although its shorter half-life, 703.8 million years, means that it is relatively depleted in this isotope. (About 1.8 billion years ago, the fraction of U-235 found in uranium ores was high enough that natural nuclear reactors operated, most famously at Oklo, in Gabon.)

There is also a related decay series for thorium-232, itself a decay product from historic Pu-244 which has more or less gone extinct on earth.

A fourth decay series, the Cm-249/Np-237 series went extinct early in Earth's history.

Fracking has allowed for the release of radon gas from the Marcellus shale uranium ores which are not being mined for uranium, but for the dangerous natural gas that is mined in ever increasing amounts while we all wait for the grand so called "renewable energy" nirvana that never comes, as I often say, like Godot.

The paper cited here at the opening is about the mechanism of the release of radon from natural gas, and the fate of that radon as it's shipped to end users.

From the introduction:

Marcellus Shale in the Appalachian basin is a middle Devonian-age shale and lies between limestone (Tristates Group) and shale (Hamilton Group).1 Pennsylvania has become the second largest shale gas-producing state because of Marcellus Shale production.2 In order to economically produce natural gas from extremely low-permeable shale formation, operators rely on hydraulic fracturing to increase the reservoir contact area, creating high-permeable conduits for natural gas to flow.3

Radon gas associated with shale gas production has come under the scrutiny of medical and environmental societies because of its potential negative impacts on the public health and environment.4−6 Radon is the daughter product of radium. Its most stable isotope is 222Rn with a half-life of 3.8 days. Radon is commonly found in the gaseous phase, but it can also partition into the aqueous phase such as contaminated brine and flowback fluids from hydraulic fracturings.7−12 Epidemiological and toxicological surveys show that exposure of radioactive radon causes lung cancer.13,14 Considering radon’s hazard to the public, the EPA set the safe level of radon concentration at 4 pCi/L. Picocuries per liter is a unit of radioactivity. Radon production from the Marcellus Shale is particularly more severe than other shale gas reservoirs and it is worth more attention. First, Marcellus Shale contains highly concentrated uranium and radium, inferring possibly high concentration of radon. Uranium concentration in rock can reach about 8.9−83.7 ppm, which is much higher than other US shale formations.15 Laboratory test measured radium concentration in hydraulic fracturing flowback water to be 1.7 × 10^4 pCi/L.16 Kondash et al.17 also pointed out that flowback water from Marcellus Shale contained unusually high levels of radium. Secondly, field measurements confirmed the existence of radon at a wellsite4 and inside a natural gas pipeline.6 Both observations indicated the radon level was higher than the safe standard. Thirdly, Marcellus Shale is close to a highly populated residential area, which implies a short transportation time for radon to decay from wellsite to residential buildings. Consequently, residents would be at risk of being exposed to hazardous radon. Therefore, it is imperative to critically evaluate the potential danger of the produced radon from Marcellus Shale.

In this paper, the author's obtained some fracked rock from a well, and also used certain kinds of computational analysis to consider how the radon escapes into the gas stream and flowback water.

An important thing to understand is that a nuclear decay is a very energetic event. The decay of radium-226 which gives rise to radon-222 occurs roughly at 4.87 million electron volts. Much of this energy is contained in the helium atom (alpha ray) ejected from the nucleus, but the conservation of momentum requires that the recoiling radon atom also has considerable energy, and can in fact travel quite far even in a solid matrix.

From the text:

The radon atoms acquire kinetic energy after the alpha decay of radium. This energy defines a finite distance, known as the recoil range.27 The kinetic energy allows the radon atoms to travel inside materials. Once the atoms lose all the energy, they stop moving. This process is known as alpha recoil. The distance traveled is material-dependent. Usually, solid materials such as rock grain require more energy than air, for example, to travel equivalent distances. In other words, the radon recoil range is shorter in the material with higher density. Typically, the recoil range in rock, water, and gas is 36, 100, and 60 000 nm, respectively.27

The authors consider two sources, radium already in the pore or on the surface of the pore, and radon that travels through the rock as part of the alpha decay.

Some remarks on the mathematical modeling of how the radium/radon system works in pores:

Some of the produced radon may stay in pore space while some may penetrate into the adjacent grains. On the other hand, for radon emanated from rock grains into pore space, the alpha recoil process is assumed as the primary mechanism. Given that radon’s half-life is 3.8 days and its low diffusivity (in range of 10−31 to 10−69 m2/s) in rock grains,28 diffusion contribution to radon emanation is negligible compared to recoil. Therefore, only radon produced within the distance of the recoil range to grain-pore surface has nonzero probability of escaping the grain. Equation 1 is modified from Hammond29 to estimate the radon concentration in pores contributed by radium in rock grains.


where, ARa is the radioactivity of radium and ARn is the radioactivity of radon, both in unit of pCi/L. Ve is the grain volume in which the radon generated from radium has nonzero possibility entering pore space, in unit of L^3. e is the emanation efficiency of recoil and Vp is pore volume in unit of L^3. Emanation efficiency e consists of two parts (eq 2). First, not all produced radon near the grain-pore surface will be emitted into pore space (fe). Some of the produced radon atoms remain inside the grain due to the inappropriate recoil direction. Second, radon atoms that enter pore space may maintain sufficient kinetic energy so that they could enter neighboring grains eventually (1 − f i). Both of these factors should be included in evaluating efficiency e


The slit pore shape is one commonly used pore geometry, defined by two parallel planes (grain surface).26 Andrews20 analytically calculated the radon release fraction from grains into pore space (fe) for slit pores. Fleischer21 further studied the fraction of radon atoms ejected from grains that are trapped in pores ( f i). Tian et al.22 investigated how much radon produced from radium in pore space will remain in slit pores after alpha recoil. Besides the slit pore shape, spherical pores also occur in shale, which require different formulas to calculate radon in situ concentration. Emanation efficiency, e, is defined in eq 2. The point O1 is the center of the spherical pore with the radius of R, as shown in Figure 1. The radium atom is initially located at O2. The radon recoil range inside fluid-filled pore space is Rf and the recoil range in solid material is Rs. The solid circle in Figure 1 represents the pore wall and, therefore, the inside of the circle is pore space. If the trajectory of radon after recoil is O2AB, it is helpful to convert the stopping power in fluid to solid.21 In other words, the distance b in the pore filled by fluid is modified to an equivalent distance bRs/Rf if the pore space is assumed to be filled by the solid. Radon particles could possibly be ejected and trapped into the pore if the following criteria are satisfied



The noble gases, including radon, are known to form clathrates with water, and water transport is an important feature. The fracturing of fracking is accomplished with water laced with a number of interesting chemicals, and this water, called "flowback" water is brought to the surface.

Radium was located in the rock grains and the formation water, as the source of radon. Because of the existence of radium, radon reached secular equilibrium,22 which indicates that the concentration of the radioactive atom remains constant as a result of the balance between the production rate and decay rate. The radium concentration in water was taken to be 1.73 × 104 pCi/L.16 The radium concentration in the solid phase was determined corresponding to radon in situ concentration. Radon was initially trapped in pore space but can partition between gas and water. The partitioning coefficient is described in eq 10.34

Once the shale reservoir development starts, radon escapes to the surface through conductive hydraulic fractures, being entrained in shale gas and formation water. The alpha decay of radium and radon in the reservoir was simulated by first-order chemical reaction because the decay rate was dependent on their concentrations (eq 11). During the simulation, fresh water was injected into the formation for 0.5 day to mimic the hydraulic fracturing process. The injected fracking fluid did not contain any radon or radium. The well was then brought back to production under a constant bottom-hole pressure after 0.5 day shut in. This work adapted model setup from Tian et al.22

where N is the concentration or radioactivity and λ is the exponential decay constant.

Some diagrams and graphics:

The caption:

Figure 1. Schematic cross-section view of the spherical pore shape. The radon generated from radium in grains (outside of the solid circle) may enter pore space (inside the solid circle). The O2A section has a length of a. The AB section has a length of b. The O2C section has a length of x. O2 represents the location of a radium molecule. After alpha decay, if the radon molecule could fall inside the solid circle, it is considered to be ejected into pore space.

Figure 2. Schematic cross-section view. Radon generated from radium in pore space (inside the solid circle) may remain in pore space. O2 represents the location of a radium molecule. After alpha decay, if the radon molecule could fall inside the solid circle, it is considered to be ejected into the adjacent grains.

Some other graphics:

The caption:

Figure 3. Synthetic model configuration. The horizontal well is located at the top. It is perforated at hydraulic fracture at the left side. The stimulate reservoir is divided into two sections: the near -fracture zone and far-formation zone.

The caption:

Figure 4. Backscattered SEM images for Marcellus Shale. (a) Organic and inorganic pores at 3 μm. The inorganic pores show the slit shape and the organic pores shows the spherical shape. In (b), the image shows more slits and sheets of illite. Illite is the dominant matrix mineral and is more visible as sheets in (c,d), creating inorganic pores around the sample.

The caption:

Figure 5. Pore size distribution for Marcellus Shale. Case A and case B are calculated through DFT using our adsorption measurements. Case C is obtained from the literature.(30)

The caption:

Figure 6. Radon in situ concentration distribution for the three cases.

Figure 7. Wellhead radon concentration with multiple initial radon in situ concentrations. The wellhead radon concentration is directly related with the in situ concentration.

The caption:

Figure 8. Wellhead radon concentration to investigate heterogeneity impact. The near-fracture zone determines the early radon production.

The concern is that the radon will persist long enough to make it to consumers. I'm sure it does.

Transport time in surface facility from the wellhead to consumers could reduce the radon levels, but radon may still be dangerous to human health. For example, assuming it takes natural gas one week to be transported from the wellhead to users, radon will decay to approximately 25% of its original concentration, considering 3.8 days half-life. That is to say, the radon concentration that entered residential buildings would be in the range of 9−25 pCi/L (based on case A), which is far above the safe standard of 4 pCi/L. Therefore, radon monitoring and protection should be implemented during Marcellus Shale gas development.



Enjoy what's left of the evening.

On the Relationship Between Highly Organized Culture and Moralizing Gods.

The paper I'll discuss in this post is this one: Complex societies precede moralizing gods throughout world history (Savage et al, Nature, Published On Line March 20, 2019)

A few weeks back, I came across a commentary in my files that I never actually read, this one: Birth of the moralizing gods (Lizzie Wade, Science, Vol. 349, Issue 6251, pp. 918-922 (2015)).

I took a brief look through it - wondering a little bit about what had caused me to download it some years back - to find a discussion of the interesting thesis that in order for a highly organized culture to arise, it was necessary to have an organized religion in which a God (or Gods) punish or reward one for one's behavior, if in no other way than in a putative afterlife, where one is judged on the (defined) morality of one's earthly behavior. This idea of punishment and reward of course is an outline of what one might call "justice."

Religion in these times is a huge force, of course, and not always for good; one wonders about our fundamentalists in this country and their worship of Donald Trump, of all beasts, without contemplating whether, by appeal to their Bible, if this awful tiny handed gnome might or might not be worshiped as described in Revelations 13, 1-18, a rather psychotic passage that reads like an acid trip, but warns of worshiping a perverted god who is, not, in fact, a god.

That's their business, not mine, except inasmuch they do ill and unethical things.

Dr. Wade's subtitle for her commentary was this: "A new theory aims to explain the success of world religions—but testing it remains a challenge."

The Nature paper linked at the outset, claims to have tested this theory using certain kinds of scales, tests, and historical (often archaeological) evidence.

From the introductory text:

Supernatural agents that punish direct affronts to themselves (for example, failure to perform sacrifices or observe taboos) are commonly represented in global history, but rarely are such deities believed to punish moral violations in interactions between humans2. Recent millennia, however, have seen the rise and spread of several ‘prosocial religions’, which include either powerful ‘moralizing high gods’ (MHG; for example, the Abrahamic God) or more general ‘broad supernatural punishment’ (BSP) of moral transgressions (for example, karma in Buddhism)9,12,16,17,18. Such moralizing gods may have provided a crucial mechanism for overcoming the classic free-rider problem in large-scale societies11. The association between moralizing gods and complex societies has been supported by two forms of evidence: psychological experiments3,6,27,28 and cross-cultural comparative analyses7,11,14,15,16,17,18,20.

The contributions of theistic beliefs to cooperation, as well as the historical question of whether moralizing gods precede or follow the establishment of large-scale cooperation, have been much debated9,10,12,23,24. Three recent studies that explicitly model temporal causality have come to contrasting conclusions. One study, which applied phylogenetic comparative methods to infer historical changes in Austronesian religions, reported that moralizing gods (BSP but not MHG) preceded the evolution of complex societies16. The same conclusion was reached in an analysis of historical and archaeological data from Viking-age Scandinavia18. By contrast, another study of Eurasian empires has reported that moralizing gods followed—rather than preceded—the rise of complex, affluent societies20. However, all of these studies are restricted in geographical scope...

The authors claim to take a broader approach as described later in the paper:

To overcome these limitations, we used ‘Seshat: Global History Databank’29, a repository of standardized data on social structure, religion and other domains for hundreds of societies throughout world history. In contrast to other databases that attempt to model history using contemporary ethnographic data, Seshat directly samples over time as well as space. Seshat also includes estimates of expert disagreement and uncertainty, and uses more-detailed variables than many databases.

To test the moralizing gods hypothesis, we coded data on 55 variables from 414 polities (independent political units) that occupied 30 geographical regions from the beginning of the Neolithic period to the beginning of Industrial and/or colonial periods (Fig. 1 and Supplementary Data). We used a recently developed and validated measure of social complexity that condenses 51 social complexity variables (Extended Data Table 5) into a single principal component that captures three quarters of the observed variation, which we call ‘social complexity’8. The remaining four variables were selected to test the MHG and BSP subtypes of the moralizing gods hypothesis. The MHG variable was coded following the MHG variable used as standard in the literature on this topic11,14,15,16,17,30, which requires that a high god who created and/or governs the cosmos actively enforces human morality. Because the concept of morality is complex, multidimensional and in some respects culturally relative—and because not all moralizing gods are ‘high gods’—we also coded three different variables related to BSP that are specifically relevant to prosocial cooperation: reciprocity, fairness and in-group loyalty.

The sampling region are shown in a map:

The caption:

The area of each circle is proportional to social complexity of the earliest polity with moralizing gods to occupy the region or the latest precolonial polity for regions without precolonial moralizing gods. For regions with precolonial moralizing gods, the date of earliest evidence of such beliefs is displayed in thousands of years ago (ka), coloured by type of moralizing gods. The three transnational religious systems that represent the first appearance of moralizing gods in more than one region—Zoroastrianism, Abrahamic religions (Judaism, Islam and Christianity) and Buddhism—are coloured red, orange and blue, respectively, whereas other local religious systems with beliefs in MHG or BSP are coloured yellow and purple, respectively. See Extended Data Table 1 for further details.

A graphic describes their findings from this approach to define the "chicken and egg" argument about the whether the concept of a moralizing god is necessary for the rise of complex societies, or whether complex societies develop these faiths in order to sustain themselves.

The caption:

a, Time series showing mean social complexity over time for 2,000 years before and after the appearance of moralizing gods. n = 12 regions with social complexity data for before and after moralizing gods. Social complexity has been scaled so that the society with the highest social complexity (Qing Dynasty, China, around AD 1900) has a value of 1 and the society with the lowest social complexity (Early Woodland, Illinois, USA, around 400 BC) has a value of 0. Vertical bands represent the period in which moralizing gods and doctrinal rituals first appeared. All errors represent 95% confidence intervals, with the exception of the vertical bar for moralizing gods, which represents the mean duration of the polity in which moralizing gods appeared (because times are normalized to the time of first evidence of moralizing gods, and there is thus no variance in this parameter). b, Histogram of the differences in rates of change in social complexity (SC) after minus before the appearance of moralizing gods. n = 200 time windows from the 12 regions. kyr, thousand years. The y axis represents the number of time windows out of 200. See Extended Data Fig. 1 for data for each of the 12 regions and Extended Data Fig. 2 for a version extending beyond 2,000 years before and after moralizing gods. The analyses in this figure treat the presence of either MHG or BSP as ‘moralizing gods’—see Extended Data Fig. 3 for an alternative analysis restricted only to the presence of MHG.

They write further:

In summary, although our analyses are consistent with previous studies that show an association between moralizing gods and complex societies7,11,14,15,16,17,18,30, we find that moralizing gods usually follow—rather than precede—the rise of social complexity. Notably, most societies that exceeded a certain social complexity threshold developed a conception of moralizing gods. Specifically, in 10 out of the 12 regions analysed, the transition to moralizing gods came within 100 years of exceeding a social complexity value of 0.6 (which we call a megasociety, as it corresponds roughly to a population in the order of one million; Extended Data Fig. 1). This megasociety threshold does not seem to correspond to the point at which societies develop writing, which might have suggested that moralizing gods were present earlier but were not preserved archaeologically. Although we cannot rule out this possibility, the fact that written records preceded the development of moralizing gods in 9 out of the 12 regions analysed (by an average period of 400 years; Supplementary Table 2)—combined with the fact that evidence for moralizing gods is lacking in the majority of non-literate societies2—suggests that such beliefs were not widespread before the invention of writing...

...Although our results do not support the view that moralizing gods were necessary for the rise of complex societies, they also do not support a leading alternative hypothesis that moralizing gods only emerged as a byproduct of a sudden increase in affluence during a first millennium BC ‘Axial Age’19,20,21,22. Instead, in three of our regions (Egypt, Mesopotamia and Anatolia), moralizing gods appeared before 1500 BC. We propose that the standardization of beliefs and practices via high-frequency repetition and enforcement by religious authorities enabled the unification of large populations for the first time, establishing common identities across states and empires25,26. Our data show that doctrinal rituals standardized by routinization (that is, those performed weekly or daily) or institutionalized policing (religions with multiple hierarchical levels) significantly predate moralizing gods, by an average of 1,100 years (t = 2.8, d.f. = 11, P = 0.018; Fig. 2a).

I'm not all that much into social science, but the role of religion in culture, for good and for bad, has always lingered in my consciousness, if only because religion was a very important part of my childhood, possibly the most important part of my childhood.

I personally know people who are highly ethical clearly because of their religion; and of course, we are all aware of - and I know several personal examples - people who excuse their lack of ethics by appeal to their religion.

I'm sure any sensible person would prefer the former, a type described both my mother and my step mother and some people with whom I work closely, and the latter by my own brother from whom I am estranged.

I'm not sure what all this may or may not mean, but in the time of awful people like Michael Pence and his ilk, the paper does inspire some interesting questions, as it is clear that under some circumstances, aggressive religious faith can serve to destabilize complex societies.

I wish you a pleasant Sunday.

Electrochemical Reduction of Carbon Dioxide Using Multiwalled Carbon Nanotubes Supporting Nickel.

The paper I'll discuss in this post is this one: Acidic Electrochemical Reduction of CO2 Using Nickel Nitride on Multiwalled Carbon Nanotube as Selective Catalyst (Kang et al ACS Sustainable Chem. Eng., 2019, 7 (6), pp 6106–6112).

It is a fundamental law of physics that the storage of energy wastes it; it is related to the fact that every energy transformation from one form into another generates heat. Anyone who owns a lap top computer can feel this if she or he places her or his hand on the battery pack while recharging it; it will be warm to the touch.

I point this out repeatedly, and am almost uniformly ignored, and in the majority of times I am not ignored, I am criticized, sometimes on the grounds that I'm rude and often insulting. Regrettably, the laws of physics do not change based on the personality of the person stating them.

Denial is not a river in Egypt; on the contrary, it is a powerful, if baleful, practice intrinsic to human nature, a dangerous practice, but a common one all the same.

Of course, people who nominally self identify as "environmentalists" without much scientific intuition about this issue of the complexity of the environment, love to prattle on about batteries, and other electrochemical transformations of electrical energy into stored chemical energy; a popular one is hydrogen produced by electrolysis. This is because many of these people are trained, in a Pavlovian fashion, by largely scientifically illiterate journalists, to believe that so called "renewable energy" will save the day; at least once we find a way to overcome the issue of its intrinsic intermittent nature by storing energy.

The pop enthusiasm for so called "renewable energy" as a meaningful tool for addressing climate change has led to the "investment" of trillions of dollars on this failed and increasingly absurd effort. I say "failed" because these "investments" of trillion dollar sums, beginning about the year 2001 and continuing to the present day have done nothing at all to address climate change. The percentage and absolute quantities of energy produced by dangerous fossil fuels has risen in the 21st century. This fact is expressed in the most dire fashion, in the reported rate of rise of the concentration the dangerous fossil fuel waste carbon dioxide in the planetary atmosphere is the highest ever observed. Since 2001, this rate with some statistical "noise," has been 2.2 ppm/year; in the last 5 years, the rate has averaged 2.6 ppm/year, and three of the five largest increases since measurement began at the Mauna Loa carbon dioxide observatory in 1958, were observed in the last 5 years. One such value (2015) exceeded 3.0 ppm/year for the first time since recording began. (The 1959 figure was 0.94 ppm over 1958.)

The reality is that energy storage of so called "renewable energy" will make it even less useful than it already is, and if your criteria for your self identification as an "environmentalist" consists of wanting to have the rate of change of carbon dioxide concentrations to be less than or equal to zero, the rise in the application so called "renewable energy" at a cost amounting to trillions of dollars has been useless. Arguably it has made things worse not better, if only for fostering delusional mythology, if not for the huge amounts of physical mass applied to it; it costs energy - almost all of it coming from dangerous fossil fuel related processing - to make silicon and steel and aluminum and neodymium iron boride magnets for wind turbines and electric cars.

A caveat to the true statement that storage of energy wastes energy is that one can obtain an energetic advantage if the stored energy is energy that is recovered that would have been wasted in any case. Consider the example of a gas turbine that is shut when the wind is blowing on a bright sunny day because so called "renewable energy" is briefly producing some large percentage of electrical demand; a figure that is likely to be dutifully reported in a blog or website by some breathless airhead. (We’ve seen these kinds of posts here lots of times.) If the gas powering the turbine is shut off the turbine will not immediately stop; it will continue to rotate, since it has stored energy in the form of rotational momentum, and this energy will be lost slowly to the friction and the resistance in the air or exhaust gases surrounding it; this energy being converted slowly into heat. However if the turbine/generator system is braked by using the residual electricity from the turbine/generator system that can no longer be applied to the grid (as it is going out of phase) to charge a battery, then some of this energy will remain available for future use. This is recovered energy. If the wind stops blowing at night, of course, additional energy - more energy than the turbine contained when it contained initially was being turned off - will be required to get it back up to the speed at which it must turn to produce appropriately phased electricity.

We often hear statements like "Scientists say..." 'x' or 'y' or 'z' in which the generic "scientists" are presented as oracular. This description of scientists as oracular is nonsense; scientists are all human beings; all have biases; and all can buy into popular mythology, at least unintentionally if not for manipulative reasons. (An example of a manipulative reason would be appealing to popular mythology in order to have their projects funded.) Many scientists include statements about how their work can be applied to improving the application of so called "renewable energy" even if the data shows it has not worked, and is not working, and thus powerfully suggests that it will not work, since repeating an experiment multiple times in hopes of getting a different result is either a reflection of scientific incompetence.

After several decades of considering the question of what we currently describe as "renewable energy" - a period over which I changed my mind about many things as I read more and more and more again - I am far more confident is stating "will not work" as something I regard as a fact than many other scientists.

The paper cited at the outset is an example. In the first sentence it makes the now traditional obeisance to "renewable energy," to wit, in it's introductory paragraph:

Increasing CO2 emission is urging researchers to develop renewable energy alternatives. CO2 can serve as a renewable carbon source for fuels or commodity chemicals.1−5 Electrochemical reduction of carbon dioxide is a promising strategy for sustainable production of chemicals under mild conditions. 2 However, because of the extreme stability of the linear CO2 molecule, electrochemical reduction of CO2 requires high activation energy to form a CO2 •− intermediate, which causes large overpotential and competitive formation of H2.6,7 Lowering the barrier of CO2 activation is necessary for developing new catalysts.

The first sentence is absurd; the second is most definitely true; the third is highly questionable since there are many other superior carbon dioxide reduction strategies that are likely to be superior. The fourth is true and is a statement of poor thermodynamic efficiency, although it is questionable that overpotentials producing hydrogen is a bad thing, since a mixture of hydrogen and carbon monoxide is key to replacing the noxious and dangerous fossil fuel petroleum, since syn gas can be used to synthetically produce equivalents of every product made from oil, including the horrible substance gasoline, and many alternatives to gasoline which are vastly superior, dimethyl ether for example. Finally the fifty statement is a statement of truth.

The next paragraph is a laundry list of other references to the (largely) electrochemical reduction of carbon dioxide focusing heavily on approaches involving nickel; it is hardly comprehensive since one can find many, many, many references to this approach, including thousands referring to other elements in the periodic table as catalysts:

Numerous CO2 reduction catalysts based on metal and metal oxides,8−13 chalcogenides,14 nitrogen-doped/-functionalized carbons,15−17 and molecular complexes18−20 have been developed. Among them, earth abundant metals have been increasingly explored as CO2 electroreduction catalysts, such as Ni,21−25 Co13,26 and Fe.27,28 Nickel-based materials have been an important class of catalysts for CO2 reduction. Ni-based complexes have been reported; for example, nickel-1,4,8,11- tetraazacyclotetradecane (Ni-cyclam) and its derivatives have shown considerable selectivity in electroreduction of CO2 to CO at Hg electrode.29−31 Recently, Li et al. reported Ni single atoms distributed in nitrogen-doped porous carbon (Ni SAs/ N−C) for selective reduction of CO2 to CO, and the highest selectivity for CO production was achieved at an overpotential of 0.89 V with Faradaic efficiency (FE) of 71.9%.32 Ni−N4 structure catalyst exhibited excellent activity for CO2RR with high FE over 90% for CO in the potential range from −0.5 to −0.9 V.24 Bao et al. reported high nickel loading materials by pyrolysis of Zn/Ni bimetallic ZIF-8 which yields high CO current density of 71.5 mA cm−2 at −1.03 V (vs RHE), and high CO FE of over 90%.23 Kamiya and co-workers prepared nickel−nitrogen-modified graphene for CO2RR with CO FEs over 90% in weakly acidic and neutral solutions.33 Strasser et al. investigated Ni−N−C catalysts with CO FEs of over 80%.34 Still, developing Ni-based catalyst is highly challenging because Ni-based nanocomposites are highly efficient for H2 evolution reaction (HER).35,36

What is different in this particular case are two things. One is that this material is being studied for use in the gas phase, although in the present case it's explored in solution. Many other electrochemical processes take place in aqueous (or other solvent) solutions. The second is that it can tolerate acid, which is a good thing, since carbon dioxide is an acidic species, a "Lewis Acid" which accepts electrons quite readily: In water it forms "carbonic acid" which is usually partially ionized to a proton and the bicarbonate ion, HCO3-. The electrodes here are nickel nitride embedded in multiwalled carbon nanotubes, otherwise known as MCNT. The reason for the use of nanotubes is to increase the exposure surface of the nickel nitride:

Reducing CO2 under acidic conditions is important for gas phase CO2 reduction. However, reducing CO2 under acidic conditions is very challenging and much less reported. In gas phase CO2 reduction, catalyst is commonly pressed onto Nafion membrane which is highly acidic in nature, requiring high selectivity for the catalyst. In Newman’s study, Ag nanoparticles loaded on Nafion only generated H2, unless they were separated with Nafion using a buffer layer.37 Making the catalyst surface with more basic sites could increase CO2 adsorption on surface and buffer the local pH. Nickel nitride (Ni3N) has low electrical resistance and decent corrosion resistance and has been used as electrocatalyst for water splitting38,39 and electrode material for supercapacitors.40 In this work, we used Ni3N/MCNT (multiwalled carbon nanotube) nanocomposites of small particle sizes...

...Using MCNT as substrate is very important for even distribution of Ni3N particles. Without MCNT, bare Ni3N was found to be large, aggregated particles (Figure S2b), suggesting that using MCNT as substrate can prevent aggregation during ammonolysis. Yet, at higher Ni loading, Ni3N/MCNT-2 became more aggregated on MCNT with larger sizes.

There is a discussion, somewhat vague, of the preparation of this electrode. The carbon nanotubes are prepared using self-assembly type molecules and this cartoon evokes the process for impregnating the nanotubes with nickel nitride.

Scheme 1. Preparation of Ni3N/MCNT

Here's some images connected with the prepared electrodes:

The caption:

Figure 1. TEM (a, b), HR-TEM (c, d), and HADDF-STEM images of Ni3N/MCNT-1 and its corresponding element mapping for C, N, and Ni (e).

The X-ray diffraction (XRD) and X-ray photoelectron spectroscopic (XPS) patterns:

The caption:

Figure 2. (a) XRD patterns of Ni(OH)2/MCNT, Ni3N/MCNT-1, and bare Ni3N; XPS spectrum for N 1s (b), Ni 2p (c) of Ni3N/MCNT-1, and N 1s (d) for N-MCNT as control.

XPS identifies elements by the method of Henry Moseley, who had his head blown off at Gallopoli in the so called "Great War," - as if wars can be "great" - and didn't live past his twenties, and thus ran out of time to collect what surely would have been a Nobel Prize.

The pore sizes as determined by nitrogen absorption isoterms:

The caption:

Figure 3. (a) Nitrogen adsorption isotherms and (b) pore size distributions of Ni(OH)2/MCNT-1 and Ni3N/MCNT-1 nanocomposites.

A graphic showing some aspects of the electrochemical performance of these electrodes with respect to the reduction of carbon dioxide to carbon monoxide.

The caption:

Figure 4. (a) CVs of Ni3N/MCNT-1 (black), Ni3N/MCNT-2 (red), and Ni(OH)2/MCNT (green) in CO2-saturated 0.5 M NaHCO3 solution at scan rate of 100 mV s–1; Faradaic efficiencies for Ni3N/MCNT-1 (b), Ni3N/MCNT-2 (c), and Ni(OH)2/MCNT (d); (e) partial current densities for CO production; (f) Tafel plots using CO partial current densities for Ni3N/MCNT-1 and Ni3N/MCNT-2.

CV here stands for an electrochemical measurement known as "cyclic voltammetry," which is a plot of current vs voltage, and describes the voltage required to induce a chemical reaction, in this case, the reduction of carbon dioxide to the monoxide.

Linear Sweep Voltametry data and Faradaic efficiency:

The caption:

Figure 5. (a) LSV scans at 50 mV s−1 for Ni3N/MCNT-1 in CO2-saturated NaCl solution at different pHs (adjusted with HCl or NaHCO3, ionic strength = 0.5 M). (b) FEs for CO (blue) (sic) and H2 (red) (sic) by Ni3N/MCNT-1 at various pHs.

Some commentary from the text on this figure:

The electrolyte pH value has significant effect on the performance of CO2RR. Figure 5a shows LSVs at different pHs from 2.5 to 7.2. Although the pH values were different, which should change the reduction potential, the LSVs mostly overlapped with each other, suggesting that the ratedetermining step is less sensitive to pH changes. Figure 5b shows the maximum FEs for CO at different pHs. The applied potentials were between −0.9 and −1.0 V. Although more acidic conditions generated more H2, still at pH 3.7, the CO FE remained at 85.7%. Yet, at pH 2.5, CO FE dropped to 50.1%. Furthermore, CO FE was only 8% at pH 1, suggesting that overly acidic pH still favors hydrogen evolution.

I'm not necessarily familiar with this technique for measuring the electrochemically active surface area:

The caption:

Figure 6. (a) Charging current densities vs CV scan rates; (b) CO2 adsorption isotherms for Ni(OH)2/MCNT and Ni3N/MCNT-1.

This text gives a feel for what is going on in this graphic:

Electrochemical surface areas (ECSAs) were determined by measuring the double-layer capacitance in CV experiments. In Figure 6a, Ni3N/MCNT-1 showed the highest ECSA of 10.87 mF cm−2, which was ca. 1.5-fold of Ni3N/MCNT-2. Increased ECSA indicates more active catalytic sites, which could contribute to increased catalytic activity for Ni3N/MCNT-1. Also, measurement of CO2 adsorption revealed that Ni3N/ MCNT-1 absorbs more CO2 (ca. 120 mg·g−1) than Ni(OH)2/ MCNT (ca. 90 mg·g−1), indicating that the nitriding strategy increased available base sites (Figure 6b).

An interesting read, I think. There's regrettably no discussion of the fate of oxygen in this paper, which, along with production bottlenecks for multiwalled carbon nanotubes, may limit any practical import for this work.

It is unlikely that this technology even were these limitations overcome would be anywhere near as thermally efficient as thermochemical approaches to the reduction of carbon dioxide to either carbon or carbon monoxide, including, but not limited to, the oxidation of biomass and other waste carbon componds with carbon dioxide at high temperatures available in nuclear energy settings.

However, there are some esoteric settings in which it might prove useful. One application concerns "spinning reserve." Most power grids require spinning reserve to adjust for unexpected fluctuations in demand. These are turbines that turn continuously, almost always dangerous natural gas driven turbines, as back up to meet sudden surges in demand without creating power dips that can damage sensitive equipment. Of course, if a grid's power supply is unstable because of surges and dips in wind speed, or the movement of clouds over solar cells, the requirement is somewhat more exigent, which is why either more gas powered spinning reserve or environmentally dubious batteries are required in the self defeating enthusiasm for so called "renewable energy."

In a sensible, nuclear powered world, one in which there was less hatred for science, electricity might be a side product of thermochemical processes designed to replace the awful petroleum industry, and one can imagine that situations might arise where gas pressure needed to be discharged, ideally against a turbine, in periods of low electricity demand, whereupon the waste electricity might be captured - albeit at a thermodynamic penalty as with any battery - by reducing stored carbon dioxide.

Have a pleasant Saturday evening.

Evaluating the Performance of Micro-Encapsulated CO2 Sorbents during CO2 Absorption and Regeneration

The paper I'll discuss in this text is this one: Evaluating the Performance of Micro-Encapsulated CO2 Sorbents during CO2 Absorption and Regeneration Cycling (Joshuah K. Stolaroff et al Environ. Sci. Technol., 2019, 53 (5), pp 2926–2936)

One of the co-authors of this paper is Dr. Joan Brennecke, of the University of Notre Dame. Over a year back, I posted a link to one of her lectures at Princeton University on the subject of phase change ionic liquids for the capture of carbon dioxide:

On the Solubility of Carbon Dioxide in Ionic Liquids.

More recently, I discussed a class of "ionic liquids," these are salts that are liquids at room temperature, most often composed of organic cations and anions, although sometimes one of the ions is inorganic in nature - a common example being the hexafluorophosphonium anion, that was being utilized for the recovery of precious metals from spent automotive catalytic converters:

Ionic Liquid Based Separation of Precious Metals from Spent Automotive Catalytic Converters.

It is a remarkable reflection on the flexibility of ionic liquids that the cation used to recover palladium and rhodium from automotive catalysts is similar to that utilized to capture carbon dioxide. The carbon dioxide capture phase change ionic liquids are designated IL NDIL0309, and IL NDIL0230. The cations in these species are tetralkyl phosphonium ions, as they are in the catalytic metal capturing, although the anions differ, in the later case being chloride ion, and in the former, imide type anions of aromatic species.

There is also a discussion of CO2-BOLs (CO2 Binding Organic Liquids) and a cyclic organic tetramine known as "cyclen" (1,4,7,10-tetraazacyclododecane).

The idea in the paper is to encapsulate these agents to improve their performance.

From the introduction to the paper:

Global carbon dioxide emissions are projected to continue increasing in the near term, with coal-consuming countries such as China and India contributing to the expected growth over the next several years.(1) The rate of increase in anthropogenic CO2 emissions more than doubled in the period from 2000–2014, to 2.5–2.7% per annum, relative to the 1.1% per annum increase in the 1990–1999 period.(2,3) The concentration of CO2 in the atmosphere now exceeds 400 ppm, the highest it has been in 670 000 years.(4) The increasing global anthropogenic CO2 emissions present a challenge to meet the international target of <2 °C increase in global temperature relative to preindustrial levels. Thus, investigating carbon capture, storage, and utilization strategies is critical to mitigating CO2 emissions and maintaining <2 °C global temperature increase.

Globally, the combustion of fossil fuels accounts for 75% of anthropogenic CO2 emissions.(2) In 2016, 35% of the U.S. energy-related CO2 emissions came from the electric power sector fed by fossil fuels.(5) One strategy for CO2 emission mitigation is postcombustion capture of CO2 from point-sources such as power plants. The conventional approach to CO2 capture from flue gas is amine-scrubbing using aqueous solutions of amines such as monoethanolamine (MEA) or diethanolamine (DEA), which is already used in a number of plants but suffers from high energy demand, mostly to regenerate the amine solvent, as well as degradation of the amine solvent and the formation corrosive degradation products.(6,7) These challenges limit the economic feasibility of postcombustion CO2 capture from powers plants. Therefore, developing novel CO2 sorbents and processes that reduce the energy requirement and/or increase the CO2 absorption rate is a vital area of research to meet CO2 emissions and global temperature goals...

Nothing I say in this post, said with the deepest respect for Dr. Brennecke, should be construed as indicating that I find carbon capture from the "flue gas" of dangerous fossil fuel power plants acceptable. This said, I do regard capture of carbon dioxide from oxyfuel closed combustion of biomass as to be one option to remove carbon dioxide from the atmosphere. Thus the basic technology attracts me, with the expectation that it can be utilized for something else besides putting lipstick on the fossil fuel pig.

I don't believe in "flues" exposing combustion products to the air we breath, but believe strongly that closed combustion is technologically feasible, particularly in light of developments in materials science. This is only possible if we can quantitatively capture carbon dioxide and chemically modify it in useful ways with the effective removal of the gas from our current modern favorite waste dump, the planetary atmosphere.

Anyway, another excerpt from the introduction:

Micro-Encapsulated CO2 Sorbents (MECS) are a recently developed CO2 capture technology that may be an effective strategy for enabling the use and recyclability of advanced solvents, but they have not been rigorously evaluated for practical use within an absorption/regeneration process until now. MECS consist of a CO2-absorbing solvent or slurry encased in spherical, CO2-permeable polymer shells.(15,16) We have demonstrated this technology with carbonates, CO2BOLs, and ionic liquids to achieve increased surface area, resulting in an enhancement of CO2 absorption rates by an order of magnitude relative to a thin film of the solvent.(16) CO2 promoters such as carbonic anhydrase,(17) sarcosine,(18) or zinc(II) cyclen complexes(19,20) may be combined with carbonate solutions in MECS to further increase the rate of CO2 absorption. We have previously explored the addition of zinc(II) cyclen, a mimic of the enzyme carbonic anhydrase that catalyzes CO2 absorption into aqueous solution, to carbonate MECS to enhance the rate of CO2 absorption and found that the capsules reached CO2 saturation 2–3 times faster than carbonate MECS without cyclen.(15) Here, we rigorously demonstrate successful encapsulation, compare absorption rates and capacities of CO2 at low partial pressure, and evaluate stability of six advanced liquid CO2 solvents within polymer shells: Na2CO3 solution (uncatalyzed, with sarcosine, with cyclen); ionic liquids (task specific ionic liquid NDIL0230, and phase-changing ionic liquid NDIL0309), and a CO2BOL (Koechanol). We build upon our previous encapsulation tests to characterize MECS performance over a wider range of temperatures, CO2 loadings, and absorption/regeneration cycles.

The preparation of MECS is described here:

Encapsulated liquid sorbents for carbon dioxide capture (Jennifer Lewis et al, Nature Communications volume 6, Article number: 6124 (2015))

The experiments herein did not involve actual flue gases, but rather carbon dioxide in the presence of water. The apparatus utilized is shown here:

The caption:

Figure 1. Process diagram of the pressure drop apparatus used to measure CO2 absorption rates as a function of time for all six MECS types.

Pressure drop was followed using the following equation to determine the mass uptake over an hour in this apparatus:

This is obviously derived from the "ideal gas law." Dr. Brennecke is the editor of the Journal of Chemical and Engineering Data where she has set a high (and appropriate) standard for precision and accuracy in data. The ideal gas law is very imprecise, but this can be forgiven here, since probably the paper is intended for qualitative analysis.

Many higher accuracy equations of state for gases exist, either for generalized gases with fitting parameters such as acentric factors for individual gases, the Peng-Robinson equation for example.

Carbon dioxide itself has a very highly precise equation of state known as the Span-Wagner equation:

A New Equation of State for Carbon Dioxide Covering the Fluid Region from the Triple‐Point Temperature to 1100 K at Pressures up to 800 MPa (Roland Span and Wolfgang Wagner Journal of Physical and Chemical Reference Data 25, 1509 (1996); https://doi.org/10.1063/1.555991)

Although modern computers can certainly address the use of cubic equations like Peng Robinson and more complex formulations like Span-Wagner, again, it's probably overkill here.

Using these microencapsulating systems, these carbon dioxide capture agents were evaluated through a number of capture and release cycles. The release, of course, requires heat, one can imagine circumstances where this heat might come from very high temperature devices in a kind of "combined cycle" approach during cool down phases, reducing exergy losses to entropy.

The regenerating device is shown here:

The caption:

Figure 2. Process diagram of regeneration in a tube furnace (A), where CO2 was stripped from all six MECS types during preliminary testing. (B) Process diagram of the regeneration apparatus used to strip CO2 using a dry stream of N2 at ∼90 °C during the 10-cycle experiments (MFC = mass flow controller, TC = temperature controller, TI = temperature indicator, CO2 = CO2 sensor, RH = relative humidity sensor, and MFI = mass flow indicator).

Upon the conclusion of these experiments, they were repeated using "simulated coal flue gas"

...We have previously measured the gas permeability of the MECS shell materials to nitrogen and CO2 separately, shown in Table 1, but had not investigated the effect of a mixed gas stream on the gas absorption rate of the MECS until now. The selectivity of a membrane between a pair of gases is given by the following:


in which PA is the permeability of the more permeable gas, and PB is the permeability of the less permeable gas.(22) In the case of both types of silicone shells used in the MECS, the selectivity for pure CO2 over pure N2 is ∼11, which is on the low end compared to other materials reported in literature.(23,24)Previous research suggests that the presence of nitrogen can reduce CO2 permeability in silicones that have similar molecular structure to the MECS shell materials,(25) which would be detrimental to the rate of CO2 absorption from coal flue gas in which nitrogen makes up ∼75% of the gas stream. In fact, Scholes et al. reported that the CO2/N2 selectivity in PDMS decreased from ∼11 with pure gases to ∼3–4 with a blend of 10% CO2, 90% N2.(26) This indicates that the CO2 absorption rate may be limited by mass transfer of CO2 to the solvent since the selectivity for CO2 is decreased in the presence of N2.

Permeability is related to molar flux, J, by the following:


where d is the thickness of the membrane, or in this case the shell thickness, and Δp is the pressure difference across the membrane. Combining eq 4 with eq 3, the ratio of fluxes is proportional to the partial pressure gradient across the shell, given by eq 5:


In order to test whether the CO2 absorption rate was affected by the presence of air, CO2 absorption tests were performed in the pressure drop chamber with 0.1 bar of injected CO2 in both cases and an additional 0.9 bar of ambient atmosphere (79% N2) injected in the case with air. The resulting total gas absorption for these two cases are compared in Figure 3 over the first 10 min. It should be noted that in the case of the experiment with air, the gas absorption includes both air (predominantly N2) and CO2 across the shell material...

The authors expected some variation with air but didn't see it:

The caption:

Figure 3. (A) Gas absorption versus time for uncatalyzed Na2CO3 MECS exposed to 0.1 bar CO2 with and without 0.9 bar air in the pressure drop apparatus at 25 °C. The loading was practically the same in pure CO2 as in CO2 with air. (B) Model calculation of CO2 mole ratio (including CO2(aq) and HCO3– ions) of CO2 and N2 in MECS (shell and core) in 0.1 bar CO2 and 0.9 bar N2 condition as a function of CO2 loading capacity. The ratio quickly approaches 100%, meaning N2 contribution to the flux and loading may be assumed to be negligible.

There is some discussion of the reasons for this.

Some of the CO2-BOLs did not stay encapsulated. This was the case for a rather interesting material known as koechanol (1-((1,3-dimethylimidazolidin-2-ylidene)amin)propan-2-ol) the synthesis of which is described here:

Low viscosity alkanolguanidine and alkanolamidine liquids for CO2 capture (David J. Heldebrant et al, RSC Adv., 2013, 3, 566-572)

Here's a photograph of the leaking koecheanol along with the effect of the leaking on cycling the microcapsules through capture and regeneration cycles:

The caption:

Figure 4. Microscope images of Koechanol CO2BOL MECS after exposure to desiccant for 4 days before cycling, with visible droplets on the shell surface. The mass of Koechanol MECS decreases dramatically with each absorption/regeneration cycle (right).

The MECS were tested with some test solutions, "promoters" without the ionic liquids or CO2-BOLs.

The caption:

Figure 5. Comparison of CO2 absorption vs time for the three types of Na2CO3 MECS: uncatalyzed MECS, MECS with sarcosine promoter, and MECS with cyclen promoter. All of these MECS contained 17 wt % Na2CO3 and were soaked in 17 wt % Na2CO3 solution prior to testing. All data were collected in the pressure drop at room temperature (25 °C). (A) CO2 absorption rate normalized by MECS mass and initial pressure, (B) CO2 loading normalized by MECS mass.

Sarcosine, which is the N-methylated analogue of the natural (and simplest) amino acid glycine, leaked from the capsules and was not pursued.

The comparison for the sodium carbonate and cyclen systems was then made with the ionic liquids:

The caption:

Figure 6. Comparison of CO2 absorption rate over the first 10 min by MECS with (A) Na2CO3-cyclen, (B) NDIL0309, and (C) NDIL0230, and at 25, 40, and 60 °C. (D) The bar graph displays CO2 loading after 30 min (left axis), and the markers represent the percent of stoichiometric capacity (right axis) of each solvent.

Not only do the ionic liquids capture more carbon dioxide per unit mass (stoichiometric capacity), but they capture it faster:

The caption:

Figure 7. Comparison of CO2 loading vs time for three MECS (NDIL0230, NDIL0309 and Na2CO3-cyclen) during Cycle 0 at 25 °C and 0.1 bar CO2. CO2 loading is presented in terms of mol/kg solvent (left) and as a percentage of total stoichiometric capacity (right).

They hold up well through multiple cycles, a very, very, very, very important issue for these types of systems.

The caption:

Figure 8. Comparison of CO2 absorbed by three MECS types (NDIL0230, NDIL0309 and Na2CO3 w/cyclen) across 10 cycles. CO2 loading capacities are the cumulative CO2 absorbed (per kg solvent and initial pressure) after the MECS have been exposed to CO2 in the pressure drop apparatus for 30 min. (A) CO2 loading is presented in terms of mol/kg. (B) The mass of the MECS is shown over 10 cycles (bars, left axis) and CO2 loading is shown as a percentage of total stoichiometric capacity (lines, right axis).

Some microscope photographs of the microcapsules, before and after:

The caption:

Figure 9. Microscope images of the three final candidate capsules taken before (top) and after (bottom) ten absorption/desorption cycles: (A) Na2CO3 before cycling; (B) NDIL0309 before cycling; (C) NDIL0230 before cycling; (D) Na2CO3 after ten cycles; (E) NDIL0309 after ten cycles; and (F) NDIL0230 after ten cycles. The scale bar for each image is 500 μm.

The authors conclude:

Overall, across the characteristics tested here—absorption rate, capacity, and cyclic stability—the ionic liquid MECS appear to be a potential competitor to aqueous amines. The major challenge to these MECS are common to solid sorbents: the need for a process configuration that is similar in capital cost and energy efficiency to aqueous solvent systems. Further work is needed on material fabrication and testing at larger scale to establish the viability of IL MECS.

While I do not believe the paper under discussion here is open sourced, there are two excellent government reports related to her DOE grants that are. They are here:

Hybrid Encapsulated Ionic Liquids for Post-Combustion Carbon Dioxide (CO 2) Capture 1337563

Hybrid Encapsulated Ionic Liquids for Post-Combustion Carbon Dioxide (CO 2) Capture 1406897

Again, I am against coal combustion, petroleum combustion and gas combustion, but I believe that biomass combustion and/or supercritical water or supercritical carbon dioxide oxidation does represent a path forward for capturing carbon dioxide from the atmosphere, and should not be overlooked, even if the combustion of biomass, as practiced now, is responsible for slightly less than half of the seven million air pollution deaths now taking place while many of us whine about Fukushima.

This kind of technology is potentially of huge importance.

I wish you a very pleasant Sunday evening.

Integrated Pest Management to Boost Dragon Fruit Production in Viet Nam

I am on the International Atomic Energy Agency's mailing list, and this note was in my email this morning:

Integrated Pest Management to Boost Dragon Fruit Production in Viet Nam

Some excerpts from the open sourced link:

There is a reason why dragon fruit is considered a rich and famous fruit in Viet Nam: it is exported to 40 countries and return from dragon fruit production is several times higher than from rice production.

In Binh Thuan province, around 29 500 hectares are dedicated to growing the fruit, with a production of nearly 600 000 tonnes last year, and its Department of Agriculture and Rural Development plans to increase that by 2020. However, this plan may be hindered by formidable pests capable of decimating dragon fruit crops: fruit flies.

“Dragon fruit is a favourite crop in Viet Nam because farmers are aware of its potential to earn them a steady income,” said Hien Thanh Thi Nguyen, Deputy Head of the Entomology Division at Viet Nam's Plant Protection Research Institute. “Unlike many other fruits that are seasonal, dragon fruit can be cultivated all year round and each crop season lasts only two and a half months, so it has great economic importance. The fruit is very important for the province’s economy, but the fruit flies are a big problem for this area.”

Therefore, the Plant Protection Research Institute, along with staff from the Agriculture and Rural Development Department of Binh Thuan province, teamed up with the IAEA and the Food and Agriculture Organization of the United Nations (FAO) in a pilot project to test the effectiveness of implementing an integrated pest management approach, including a form of insect pest control known as the Sterile Insect Technique (SIT). Using this technique, fruit flies are mass-produced and then sterilized using ionizing radiation before being released into the environment to mate with wild flies, producing no offspring.

The technique is designed to reduce the fruit fly population by releasing sterilized animals into the area where they mate with fertile animals (who mate only once) resulting in a failure to reproduce.

The technique can be utilized either to eliminate or greatly reduce dependence on pesticides.

The program met resistance, until authorities were able to educate the farmers:

Getting to the point of SIT implementation has not been easy, due to limited knowledge of the technique within the local offices and resistance from dragon fruit farmers, who did not at first understand how releasing more flies into the fields would ultimately reduce the population.

“They didn’t understand that the fruit fly would be sterilized,” said Hien. “They would say, ‘We have so many flies already, how can we combat this by bringing in more flies?’ So, we had to change the way we approached farmers about this with a series of trainings, leaflets and television advertisements, and it took about two years before they started thinking that maybe this could help. It’s important because getting the programme to work depends on the farmers in the entire area actively participating in the pest management.”

It appears that the farmers were able to overcome their initial ignorance; I kind of, sorta, after a fashion, wish American anti-nukes were willing to address their ignorance, but that's not likely to happen. (We have a "Nuclear Free" group here at DU, but not a "Fossil Fuel Free" group.) Anti-nukes are very cult like, in the sense that no amount of information can cause them to change their minds.

It is interesting to note that Agent Orange, a persistent chlorinated aromatic compound routinely dumped on Vietnam for defoliation, can be dechlorinated by irradiation, as can many historical chlorinated pesticides, of which DDT is the most famous example.

In many cases there are no other techniques that can or will work.


I wish you a pleasant Sunday afternoon.

A nice little open sourced paper on "Sloshing."

I always like to hear about things at which I never spent much time - or any time - thinking, and to learn more about them.

Recently my son - on his spring break - visited one of the last independent bookstores of which I am aware, and came across a book in the Engineering section called "Sloshing." He found the title amusing and told me about it.

He didn't buy it, but its appearance in an engineering section led me to realize that, "Of course, there is a physics of sloshing."

Late in life, I've become more and more interested in fluid dynamics owing to a growing interest in the behavior of liquid metal nuclear fuels, eutectics of the low melting metals plutonium and neptunium, generally are very dense liquids.

Anyone who has ever handled a large flask of mercury or elemental bromine, can get a quick feel for the potential of forces involved in sloshing. Liquid plutonium is more dense than liquid mercury. The density of mercury is about 13.5 grams/ml; liquid plutonium, depending on temperature, as a density of between 16.0 and 16.7 grams/ml. (cf. L. J. WITTENBERG, D. OFTE, and W. G. ROHR, Properties of Liquid Plutonium (Nuclear Applications Volume 3, 1967 - Issue 9 pp 550-555.)

In addition, I favor liquid metal reactor coolants consisting largely - or entirely - of lead, a very dense metal.

The physics of these liquid metal materials have implications for the strength of materials with which they interact, in particular in events like earthquakes, so it's a very important topic.

Anyway, it's a topic into which I will look further, and a quick Google Scholar search - the way I always begin exposure to a new topic led me to this link to an open sourced paper: Sloshing (Faltensen, O.M. FFALTINSEN. Sloshing. Advances in Mechanics, 2017, 47: 201701)

(There's Japanese text but the paper is in English.)

It has interesting little bits like considering what liquids do in outer space where there is no gravity.

Cool, I think.

If interested, enjoy.

I hope you're having a pleasant Weekend.

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