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kristopher (1000+ posts) Send PM | Profile | Ignore | Mon Jan-18-10 07:50 PM Response to Reply #12 |
13. The paper DOES addresses the MYTH of baseload electricity. |
You are engaging in the typical obsfucation that is the trademark of nuclear power's supporters.
YOU are the one claiming the 60% figure and you've yet to support it. First I asked you do define it. You have even now (two posts later) not explained exactly what you mean by "baseline" as opposed to "baseload" and why the discussion in the OP paper is flawed. Your unsupported opinion and a meaningless graph isn't enough. The “baseload” myth Brand rejects the most important and successful renewable sources of electricity for one key reason stated on p. 80 and p. 101. On p. 80, he quotes novelist and author Gwyneth Cravens’s definition of “baseload” power as “the minimum amount of proven, consistent, around-the-clock, rain-or-shine power that utilities must supply to meet the demands of their millions of customers.”21 (Thus it describes a pattern of aggregated22 customer demand.) Two sentences later, he asserts: “So far nuclear.” Two paragraphs later, he explains this dramatic leap from a description of demand to a restriction of supply: “Wind and solar, desirable as they are, aren’t part of baseload because they are intermittent—productive only when the wind blows or the sun shines. If some sort of massive energy storage is devised, then they can participate in baseload; without it, they remain supplemental, usually to gas-fired plants.” That widely heard claim is fallacious. The manifest need for some amount of steady, reliable power23 is met by generating plants collectively, not individually. That is, reliability is a statistic- al attribute of all the plants on the grid combined.24 If steady 24/7 operation or operation at any desired moment were instead a required capability of each individual power plant, then the grid couldn’t meet modern needs, because no kind of power plant is perfectly reliable. For example, in the U.S. during 2003–07, coal capacity was shut down an average of 12.3% of the time (4.2% without warning); nuclear, 10.6% (2.5%); gas-fired, 11.8% (2.8%).25 Worldwide through 2008, nuclear units were unexpectedly unable to produce 6.4% of their energy output.26 This inherent intermittency of nuclear and fossil-fueled power plants requires many different plants to back each other up through the grid. This has been utility operators’ strategy for reliable supply throughout the industry’s history. Every utility operator knows that power plants provide energy to the grid, which serves load. The simplistic mental model of one plant serving one load is valid only on a very small desert island. The standard remedy for failed plants is other interconnected plants that are working—not “some sort of massive energy storage Modern solar and wind power are more technically reliable than coal and nuclear plants; their technical failure rates are typically around 1–2%. However, they are also variable resources because their output depends on local weather, forecastable days in advance with fair accuracy and an hour ahead with impressive precision.27 But their inherent variability can be managed by proper resource choice, siting, and operation.28 Weather affects different renewable resources differently; for example, storms are good for small hydro and often for windpower, while flat calm weather is bad for them but good for solar power. Weather is also different in different places: across a few hundred miles, windpower is scarcely correlated, so weather risks can be diversified. A Stanford study found that properly interconnecting at least ten windfarms can enable an average of one-third of their output to provide firm baseload power.29 Similarly, within each of the three power pools from Texas to the Canadian border, combining uncorrelated windfarm sites can reduce required wind capacity by more than half for the same firm output, thereby yielding fewer needed turbines, far fewer zero-output hours, and easier integration.30 A broader assessment of reliability tends not to favor nuclear power. Of all 132 U.S. nuclear plants built—just over half of the 253 originally ordered—21% were permanently and prematurely closed due to reliability or cost problems. Another 27% have completely failed for a year or more at least once. The surviving U.S. nuclear plants have lately averaged ~90% of their full-load full-time potential—a major improvement31 for which the industry deserves much credit—but they are still not fully dependable. Even reliably-running nuclear plants must shut down, on average, for ~39 days every ~17 months for refueling and maintenance. Unexpected failures occur too, shutting down upwards of a billion watts in milliseconds, often for weeks to months. Solar cells and windpower don’t fail so ungracefully. Power plants can fail for reasons other than mechanical breakdown, and those reasons can affect many plants at once. As France and Japan have learned to their cost, heavily nuclear-dependent regions are particularly at risk because drought, earthquake, a serious safety problem, or a terrorist incident could close many plants simultaneously. And nuclear power plants have a unique further disadvantage: for neutron-physics reasons, they can’t quickly restart after an emergency shutdown, such as occurs automatically in a grid power failure. During the August 2003 Northeast blackout, nine perfectly operating U.S. nuclear units had to shut down. Twelve days of painfully slow restart later, their average capacity loss had exceeded 50%. For the first three days, just when they were most needed, their output was less than 3% of normal.32 To cope with nuclear or fossil-fueled plants’ large-scale intermittency, utilities must install a ~15–20% “reserve margin” of extra capacity, some of which must be continuously fueled, spinning ready for instant use. This is as much a cost of “firming and integration” as is the corresponding cost for firming and integrating windpower or photovoltaic power so it’s dispatchable at any time.33 Such costs should be properly counted and compared for all generating resources. Such a comparison generally favors a diversified portfolio of many small units that fail at different times, for different reasons, and probably only a few at a time: diversity provides reliability even if individual units are not so dependable. Reliability as experienced by the customer is what really matters, and here the advantage tilts decisively towards decentralized solutions, because ~98–99% of U.S. power failures originate in the grid. It’s therefore more reliable to bypass the grid by shifting to efficiently used, diverse, dispersed resources sited at or near the customer. This logic favors onsite photovoltaics, onsite cogeneration, and local renewables over, say, remote windfarms or thermal power plants, if complemented by efficient use, optional demand response, and an appropriate combination of local diversification and (if needed) local storage, although naturally the details are site-specific. The big transmission lines that remote power sources rely upon to deliver their output to customers are also vulnerable to lightning, ice storms, rifle bullets, cyberattacks, and other interruptions. These vulnerabilities are so serious that the U.S. Defense Science Board has recommended that the Pentagon stop relying on grid power altogether.34 The bigger our power plants and power lines get, the more frequent and widespread regional blackouts will become. In general, nuclear and fossil-fueled power plants require transmission hauls at least as long as is typical of new windfarms, while solar potential is rather evenly distributed across the country. For all these reasons, a diverse portfolio of distributed and especially renewable resources can make power supplies more reliable and resilient. Of course the weather-caused variability of windpower and photovoltaics must be managed, but this is done routinely at very modest cost. Thirteen recent U.S. utility studies show that “firming” variable renewables, even up to 31% of total generation, generally raises windpower’s costs by less than a half-cent per kWh, or a few percent.35 Without exception, ~200 international studies have found the same thing.36 Indeed, the latest analyses are suggesting that a well-diversified and well-forecasted mix of variable renewables, integrated with dispatchable renewables and with existing supply- and demand-side grid resources, will probably need less storage or backup than has already been installed to cope with the intermittence of large thermal power stations. Utilities need only apply the same techniques they already use to manage plant or powerline outages and variations in demand—but variations in renewable power output are more predictable than those normal fluctuations, which often renewables’ variations don’t augment but cancel. Thus, as the U.S. Department Energy pithily summarizes, “When wind is added to a utility system, no new backup is required to maintain system reliability.”37 This is not just a computational finding but a practical reality. In 2008, five German states got 30–40% of their annual electricity from windpower—over 100% at windy times—and so do parts of Spain and Denmark, without reliability problems. Denmark is 20% windpowered today and aims for ~50–60% (the rest to come from low- or no-carbon cogeneration). Ireland, with an isolated small grid (~6.5 billion watts), plans to get 40% of its electricity from renewables, chiefly wind, by 2020 and 100% by 2035. Three 2009 studies found 29–40% British windpower practical.38 The Danish utility Dong plans in the next generation to switch from ~15% renewables (mainly wind) and ~85% fossil fuel (mainly coal) to the reverse. A German/Danish analysis found that diversifying supplies and linking grids across Europe and North Africa could yield 100% renewable electricity (70% windpowered) at or below today’s costs.39 Similar all- renewable scenarios are emerging for the United States and the world, even without efficiency.40 Brand nonetheless concludes that “wind power remains limited by intermittency to about 20 percent of capacity (so that 94 gigawatts four-fifths illusory), while nuclear plants run at over 90 percent capacity these days; and there is still is no proven storage technology that would make wind a baseload provider.” That view has long been known to be unfounded. There is no 20% limit, in theory or in practice, for technical or reliability or economic reasons, in any grid yet studied.41 The “fourth-fifths illusory” remark also appears to reflect confusing an imaginary 20% limit on windpower’s share of electrical output with windpower’s capacity factor (how much of its full-time full-power output it actually produces). Anyhow, capacity factor averaged 35–37% for 2004–08 U.S. wind projects, is typically around 30–40% in good sites, and exceeds 50% in the best sites.42 Proven and cost- effective bulk power storage is also available if needed.43 Even if Brand were right that variability limits windpower’s potential contribution, that would be irrelevant to windpower’s climate-protecting ability. Grid operators normally44 dispatch power from the cheapest-to-run plants first (“merit order” or “economic dispatch”). Windpower’s operating cost is an order of magnitude below coal’s, because there’s no fuel—just minor operating and maintenance costs. Therefore, whenever the wind blows, wind turbines produce electricity, and coal (or sometimes gas) plants are correspondingly ramped down, saving carbon emissions. Coal makes 50% of U.S. electricity, so on Brand’s own assumption of a much smaller (20%) windpower limit, windpower saves coal and money no matter when the wind blows. To put it even more simply, physics requires that electricity production and demand exactly balance at all times, so electricity sent out by a wind turbine must be matched by an equal decrease in output from another plant—normally the plant with highest operating cost, i.e. fossil-fueled. Further layers of fallacy underlie Brand’s amiable dismissal of solar power (pp. 101–102): • For photovoltaics (PVs) to become “a leading source of electricity” does not require numerous “breakthroughs, sustained over decades”; it requires only the sort of routine scaling and cost reduction that the similar semiconductor industry has already done. Just riding down the historic Moore’s-Law-like “experience curve” of higher volume and lower cost—a safe bet, since a threefold cost reduction across today’s PV value chain is already in view—makes PVs beat a new coal or nuclear plant within their respective lead times. That is, if you start building a coal, gas, or nuclear power plant in, say, New Jersey, and next door you start at the same time to build a solar power plant of equal annual output, then by the time the thermal plant is finished, the solar plant will be producing cheaper electricity, will deliver ~2.5× a coal plant’s onpeak output, will have enjoyed more favorable financing because it started producing revenue in year one, and will have been made by photovoltaic manufacturing capacity that can then reproduce the solar plant about every 20 months45—so you’d be sorry if you’d built the thermal plant. • Photovoltaics’ business case, unlike nuclear’s, needn’t depend on government subsidies or support. Well-designed photovoltaic retrofits are already cost-effective in many parts of the United States and of the world, especially when integrated with improved end-use efficiency and demand response (e.g., PowerLight’s 2002 retrofit of three acres of PVs on the Santa Rita Jail46) and when financed over the long term like power plants, e.g., under the Power Purchase Contracts that many vendors now offer. PVs thrive in markets with little or no central-government subsidy, from Japan (2006–08) to rural Kenya, where electrifying households are as likely to buy them as to connect to the grid. • Photovoltaics are highly correlated with peak loads; they often exhibit 60% and sometimes 90% Effective Load Carrying Capacity (how much of their capacity can be counted on to help meet peak loads). PV capacity factors can also be considerably higher than Brand’s assumed 0.14, especially with mounts that track towards the sun: modern one-axis trackers get ~0.25 in New Jersey or ~0.33–0.35 in sunny parts of California.47 • Solar power, Brand asserts, does not work well at the infrastructure level (i.e., in substantial installations feeding power to the grid; the largest installations in spring 2009 produced about 40–60 peak megawatts each). This will surprise the California utilities that recently ordered 850 megawatts of such installations, the firms whose reactor-scale PV farms are successfully beating California utilities’ posted utility price in 2009 auctions, the firms that are sustaining ~60–70% annual global growth in photovoltaic manufacturing, and their customers in at least 82 countries. Global installed PV capacity reached 15.2 GW in 2008, adding 5.95 GW (110% annual growth) of sales and 6.85 GW of manufacturing (the rest was in the pipeline).48 That’s more added capacity than the world nuclear industry has added in any year since 1996, and more added annual output than the world nuclear industry has added in any year since 2004. About 90% of the world’s PV capacity is grid-tied. Its operators think it works just fine. The belief that solar and windpower can do little because of their variability is thus exactly backwards: these resources, properly used, can actually become major or even dominant ways to displace coal and provide stable, predictable, resilient, constant-price electricity. Full paper (with notes) available for download here: http://www.rmi.org/rmi/Library/2009-09_FourNuclearMyths |
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