Why I like "exajoules per year"

[phantom power]

(I just thought I'd go ahead and give this it's own thread, since it cuts across so many of our topics)

Regardless of our disagreements over the various merits of renewables and nuclear power, I genuinely don't see why we can't agree that the measure "exa-joules per year" is a very good measure for comparing energy sources, and better than watts, or peak-watts, or what-have-you.

Here's why I think that: measuring per-year basically integrates out all the variability that any energy source experiences. Using exa-joules per year is just a choice of scaling, but it's a good one because the world uses 400 exa-joules per year, so we can talk in convenient numbers like "0.14 exajoules/year", instead of annoying numbers like "1.4e+17 joules/year."

It makes the scales easy to understand. If somebody installs a wind-farm that produces 1 exajoule/year off the atlantic coast, then I know intuitively that it provides about 1% of the US energy usage, since we use about 105 exajoules each year.

It's not a word we should use to make fun of each other with. It's a conceptual tool we can all use to help each other better understand what the hell is going on.

Who's with me!

[eallen]

1. I completely agree you can't compare joules and watts.

For the same reason you can't compare yards and tons, or degrees farenheit and miles per hour.

[phantom power]

2. it's worth noting that "exajoules/year" is still a measure of power, like watts.

it just happens to extend over a time-span (a year) that smooths out power variations, and so gets around the inconvenient difference between "power output" and "peak power output"

[GliderGuider]

3. It's got my vote.

Simple, clean, nice scaling.

[jpak]

4. Apples and oranges and shoehorning and wrong.

Comparing gasoline or coal consumption to wind/PV electricity production or total US energy demand is a little silly.

It doesn't account for externalities (GHG emissions) or unique applications of different energy sources (ex., high quality electrical energy from PV vs. low temperature heat from solar thermal, high quality gasoline energy vs. low quality lignite energy, etc).

It's like the old ERDA metric "Quads" (quadrillion BTU) - how many BTUs does an electric train use per kilometer???? How many quads does an LED light bulb use???

Furthermore, 400 exajoules is the energy used by an unsustainable fossil fuel-consuming-greenhouse-gas-belching global society/economy.

Peak Oil and Gas will reduce those 400 exo-jewels dramatically over then next 50 years. 400 exo-jewels is not a valid benchmark for any analysis of energy production or consumption in the US or globally.

Are there exajoules of energy efficiency??? How does one measure that???

Neg-'o-exo-jewels???

How 'bout Embodied Energy and recycled materials - can this be measured or described by a one-size-fits-all energy metric???

(no)

Required reading: H.T. Odum (1971) Environment, Power and Society. , John Wiley, New York (1971) 336 pp.

All will be explained Grasshopper...

[Dead_Parrot]

5. You may need to learn some basic math

But it really is about time. A Joule is a Watt per second, so it's not exactly advanced calculus.

And yes, you can measure efficiency in joules. For instance, I have a light fitting over my head, which is on for about 2 hours each night. Replacing the 100W incandescent bulb with a 25W CF saves 197.1 MJ over a year: Cutting down to using it for just 1 hour, saves another 32.85 MJ per year.

The Joule is the standard measurement of energy. If you are going to insist on talking about energy efficiency without talking about energy, you will just be spouting gibberish. Again.

[jpak]

6. Again???

Go to varlet...

:evilgrin:

[Dead_Parrot]

8. :-P nt

[suziedemocrat]

11. "A Joule is a Watt per second" - thanks!

I never knew what a Joule was. I come to this forum a lot, but I still miss so much, and if the basics aren't repeated in a thread, I'm lost.

[phantom power]

13. actually, a Watt is a Joule/sec.

[Dead_Parrot]

14. Oh, go measure the PH of some acid.

:P

(and thanks for spotting it)

[phantom power]

19. You really know how to hurt me. I think I want to be alone right now.

:evilgrin:

[phantom power]

7. I would say that exajoules/year is a good way to discuss those issues too.

If you want to argue about how far energy efficiency can get us, you can discuss how many exajoules/year we will save by adopting energy efficiency measures.

If you want to talk about peak oil, you can talk about how many exajoules/year worth of oil capacity we are losing.

In fact, it's a great way to talk about such issues, since it puts it on scale with our current global energy usage (400 exajoules/year).

Whether or not 400 exajoules/year is sustainable is a whole other argument, but either way it's easy enough to express whatever you think is sustainable in the same exajoules/year units. Do you think 100 exajoules/year is sustainable? Or 50? It's just a unit.

[Dogmudgeon]

17. "Exo-Jewels" ... is that like when Freepers call Al Gore "Algore"?

:shrug:

--p!

[NNadir]

9. Well my vote on this subject is pretty clear.

It's cuts away bullshit.

That - cutting away bullshit - is going to prove highly controversial. It always does, especially among those who produce bullshit.

The exajoule is a physical SI unit. The purpose of the having SI units at all is to reduce confusion. There really shouldn't be any controversy about it. It's good, and very basic, science.

Other units of energy are frequently found, for instance the kilowatt-hour, or the megawatt-hour, or the quad. They are not SI units and, in the case of the "kilowatt-hour," and "megawatt-hour" serve as a source of confusion, not clarity. The "kilowatt-hour" in particular is generally used in such a way as to obscure the use of primary energy, since it is most generally used to measure electricity and not the primary energy consumed to generate that electricity.

If you are a "renewables will save us" energy advocate nothing could be worse than the unit of power "exajoules per year," though. It will make the argument seem foolish, which of course, the "renewables will save us," argument is.

[piedmont]

10. NNadir, I have a couple of questions about your outlook.

You're an advocate of expanding nuclear power production. I can understand that-- I'm not squemish about nuclear. But statements like "It will make the argument seem foolish, which of course, the "renewables will save us," argument is." make me wonder a couple of things. How long do you expect nuclear power to be able to meet society's energy needs? Indefinitely? What happens when we run out of ore for the reactor fuel? When that day comes, won't renewables be the only game in town? Or do you think we'll transition to fusion reactors after that?

[Massacure]

15. Set up correctly, the nuclear industry will never run out of fuel

There have been studies that have shown that even if we were to get 100% of our energy from breeder reactors, uranium and thorium reserves would not exhaust until after the sun becomes a red giant and engulfs Earth. In a nutshell humans would need to extract uranium and thorium from seawater and use it in breeder reactors that can fission not only uranium and thorium but their daughter products as well. This allows Earth to replenish the supplies of uranium and thorium in the oceans via the process of erosion faster than we take it out. The U.S. did an experiment with breeders with a reactor called the Integral Fast Reactor. It fissioned and reprocessed nuclear waste down to the point where it will be less radioactive than the original ore in four hundred years, which shows great promise in regards to dealing with waste. Unfortunately, Clinton killed the project during his presidency.

Breeder reactors have shown some technological problems, particularly dealing with sodium. The reactors will no doubt start off very expensive, but research continues with them. The people involved with those projects are not holding their breath on solar and wind, that is for sure.

[NNadir]

16. The last time we lived on renewables, the world's population was about

1 billion.

People seem to think that living off renewable energy is a new idea, but it is not. There is a reason that people stopped relying on renewable energy, and it had everything to do with the same issues that still apply: Renewable energy is diffuse. It is not reliable. It does, in fact, incur an external cost, and a significant one at that.

I do not know how long world uranium resources will last, but I fully expect them to last for several millenia, if not much, much, much longer, especially if humanity, either by means of tragedy or by rational action, reduces the population significantly.

There's a lot of hand-waving about geothermal energy. It's one of those happy face panaceas about which people love to wax romantic.

Geothermal energy is the only source of "renewable" energy that does not derive as its primary source from fusion reactions in the sun. In fact, the source of this energy is decay heat from nuclear reactions - primarily alpha decay - in the earth's core. The scale of this energy gives some idea about how much uranium and thorium is in the earth.

Whether we can get at it is another question, but I will tell you for certain that traditional ores are at best the tip of the iceberg. The energy density of uranium is so high that the rules of "peak this" and "peak that," are not all that relevant.

The earth's oceans are saturated with respect to uranium. This uranium is recoverable at a reasonable thermodynamic penalty, ironically because of the solar energy represented by ocean currents. Thus if uranium is removed from the ocean, it is likely to be replenished by recycling and weathering of the crust. It is thus conceivable, but hardly proved, that uranium is in fact a renewable resource. That said, it is reasonable to behave as if this is not the case, and that thorium and uranium are exhaustible.

The economic costs of recovering uranium from seawater are well understood. Although the costs in financial terms are significantly higher than current costs, they are not actually prohibitive at all.

That said, the construction of 3000 nuclear plants - a reasonable number that I think is almost certainly necessary - would not remove the desirability of conserving and impetus to conserve. We must conserve and we should conserve, but that does not mean that we should not use the only truly new form of primary energy discovered in the last several hundred years.

I cannot say whether this notion about uranium as a renewable resource will hold, but I submit that the matter is not one for immediate debate in any case. Unless five out of six people agree to commit suicide for environmental reasons, renewable energy other than nuclear is not a reasonable option for the near term.

[suziedemocrat]

12. self delete

[Dead_Parrot]

21. I'd disagree about kWh et al.

They have a nice, intuitive feel to them, especially at the low end of the scale: Wasting a kWh a day on my TV seems a lot worse than wasting 3.6 MJ. Although I tend to wander up into TWh without a thought, so a slap with a wet fish is probably in order.

And they're almost SI...

[conning]

18. British thermal units

are another good way to compare various energy sources and their associated carbon dioxide emissions. The Energy Information Administration uses the btu for some of their comparative reports.

I have found it convenient to use the btu measurement as a way of understanding my own energy use and its impact on the environment. For example, my apartment is supplied with heat from natural gas which is billed by the therm which is valued at 100,000 therms. Multiplying that number by the number of therms I use in a season shows how many million btu have been used. Natural gas emits 117 pounds of CO2 for every million btu and so I can figure out how much CO2 I have caused to be added to the atmosphere.

My electricity provider, Rochester Gas & Electric, gets 87% of its power from nuclear, 8% from hydro, 1% from wind, 2% from coal, and 2% from oil. One kilowatt hour holds 3412 btu; multiplying my usage times that number tells me how many million btu I'm using. Only 4% of my electricity is from fossil fuels, and so the carbon dioxide emitted is negligible.

Having that basis for comparison, I decided to use electrical space heaters this winter in lieu of the natural gas heat. My records show that my energy use is quite reduced and that my contibution to CO2 is reduced to irrelevance.

As I sit here typing while temperatures outside are in the single digits, most of my apartment is in the low 50's. However, I am very comfortable sitting in front of a radiant heater that is like a portable fireplace. The computer mouse and keyboard are on top of heating pads. Wool sweater and wool socks add to my comfort.

[phantom power]

20. BTUs are a good scale for household use.

Although they're also non-metric. My physics training commands me to convert BTUs into kilowatt-hours :-)

For discussing energy on the scale of a nation, or the world, BTUs or kilowatt-hours are somewhat too small to be convenient (imo).