Efficiency, capacity factor, and value

To the Editor, Geelong Advertiser:

As a science editor, I share Heinz Dahl's frustration with the inaccurate use of terms in characterizing wind energy on the grid ("Winds of change", Opinion, October 30th).

But while pretending to clarify terms, Mr. Dahl only further confuses them as he evades their unique application to wind energy.

Efficiency is not the issue. It is well understood that burning coal for electricity is only around 30 per cent efficient.

It is also well known that wind turbines generate power at an average rate of around 30 per cent of their full capacity. And although it is technically incorrect to call that their "efficiency", the word nonetheless conveys the problematic nature of wind turbines.

In common use, we don't consider our car to be only 5 per cent efficient because we drive it only an hour or so each day. If we're lucky, we consider it to be 100 per cent efficient because whenever we need it, it runs.

Mr. Dahl says that wind turbines are nearly always available, which is true. Except that if the wind isn't blowing, they aren't. And if the wind is blowing, but not within an ideal range of speed (roughly 30-60 mph), the power generated is much less than the turbines' capacity. In that sense, they are much less efficient than conventional plants which when you turn them on run reliably at full throttle.

That's the difference. Unlike conventional generators, wind turbines respond only to the wind, not to actual demand on the grid.

To pretend that there is some value in that, Mr. Dahl invents a new term, "availability capacity factor", but seems only to apply the attributes of a dispatchable conventional plant to the intermittent and variable nondispatchable output of a wind plant.

He says that when wind energy facilities have a capacity factor of 30 per cent, that means that "30 per cent of the time they are generating at full capacity".

He is completely wrong. That is what a 30 per cent capacity factor means for a conventional power plant, i.e., that it is used 30 per cent of the time.

But because the output from a wind turbine varies with the wind speed, 30 per cent capacity factor for a wind plant means that its output averages 30 per cent of its capacity. In fact, it very rarely reaches full capacity and generates at or above its average rate (i.e., 30 per cent) only about 40 per cent of the time.

Which brings us to the measure that Mr. Dahl ignored: capacity value. When power is needed on the grid, can wind plants provide it? Only by chance. Their capacity value is effectively zero. The rest of the grid still has to be kept up and running.

Next it might be you

NIMBY. It's called being a citizen.

Eating as if the climate mattered

By Bruce Friedrich

The National Council for Science and the Environment (NCSE) held a climate-change conference, January 16 to 18 2008 in Washington DC, which focused on solutions to the problem of human-induced climate change. And the same week, in Paris, the head of the Intergovernmental Panel on Climate Change (IPCC), which is sharing the Nobel Peace Prize with Al Gore, held a press conference to discuss "the importance of lifestyle choices" in combating global warming.

Notably, all food at the NCSE conference was vegan, and there were table-top brochures with quotes from the U.N. report on the meat industry, discussed more below. And the IPCC head, Dr. Rajendra Pachauri declared, as the Agence France-Presse (AFP) sums it up, "Don't eat meat, ride a bike, and be a frugal shopper."

The New York Times, also, seems to be jumping on the anticonsumption bandwagon. First, they ran an editorial on New Year's Day stating that global warming is "the overriding environmental issue of these times" and that we Americans are "going to have to change [our] lifestyles". The next day, they ran a superb opinion piece by Professor Jared Diamond about the fact that those of us in the developed world consume 32 times as many resources as people in the developing world and 11 times as much as China. Diamond ends optimistically, stating that "whether we get there willingly or not, we shall soon have lower consumption rates, because our present rates are unsustainable." It is reasonable for all of us to review our lives and to ask where we can cut down on our consumption--because it's necessary, and because living according to our values is what people of integrity do.

In November 2007, the United Nations environmental researchers released a report that everyone who cares about the environment should review. Called Livestock's Long Shadow, this 408-page thoroughly researched scientific report indicts the consumption of chickens, pigs, and other meats-concluding that the meat industry is "one of the ... most significant contributors to the most serious environmental problems, at every scale from local to global", and that eating meat contributes to "problems of land degradation; climate change and air pollution; water shortage and water pollution; and loss of biodiversity."

The environmental problems of meat fill books, but the intuitive argument can be put more succinctly into two points:

1) A 135-pound woman will burn off at least 1,200 calories a day even if she never gets out of bed. She uses most of what she consumes simply to power her body. Similarly, it requires exponentially more resources to eat chickens, pigs, and other animals, because most of what we feed to them is required to keep them alive, and much of the rest is turned into bones and other bits we don't eat; only a fraction of those crops is turned into meat. So you have to grow all the crops required to raise the animals to cat the animals, which is vastly wasteful relative to eating the crops directly.

2) It also requires many extra stages of polluting and energy-intensive production to get chicken, pork, and other meats to the table, including feed mills, factory farms, and slaughterhouses, all of which are riot used in the production of vegetarian foods. And then there are the additional stages of gas-guzzling, pollution-spewing transportation of moving crops, feed, animals, and meat-relative to simply growing the crops and processing them into vegetarian foods.

So when the U.N. added it all up, what they found is that eating chickens, pigs, and other animals contributes to "problems of land degradation; climate change and air pollution; water shortage and water pollution; and loss of biodiversity," and that meat-eating is "one of the ... most significant contributors to the most serious environmental problems, at every scale from local to global."

And on the issue of global warming, the issue the New York Times deems critical enough to demand that we "change [our] lifestyles" and for which Al Gore and the IPCC received the Nobel Peace Prize, the United Nations' scientists conclude that eating animals causes 40 percent more global warming than all planes, cars, trucks, and other forms of transport combined, which is why the Live Earth Global Warming Survival Handbook says that "refusing meat [is] the single most effective thing you can do to reduce your carbon footprint."

There is a lot of important attention paid to population, and that's a critical issue too, but if we're consuming I I times as much as people in China and 32 times as much as people in the third world, then it's not just about population; it's also about consumption.

NCSE, IPPC, and the U.N. deserve accolades for calling on people to stop supporting the inefficient, fossil fuel intensive, and polluting meat industry. The head of the IPCC, who received the Nobel Prize with Mr. Gore and who held last week's press conference in Paris, puts his money where his mouth is: He's a vegetarian.

The NCSE's all-vegan 3,000-person conference In January, also, sends a positive signal that other environmentalists would be wise to listen to. Thus far, among the large environmental organizations, only Greenpeace ensures that all official functions are vegetarian. Other environmental groups should follow suit.

It's empowering really, when you think about it: By choosing vegetarian foods, we're making compassionate choices that are good for our bodies, and we're living our environmental values at every meal.

American Vegan 8-1, Summer 2008, pages 12-13

World GO VEGAN Days, Oct. 25-31, 2008

Two S.D. universities claim to be 100% wind powered while getting the same electricity as everyone else

An Oct. 15 press release from Babcock & Brown states:

The 51-megawatt (MW) Wessington Springs Wind Farm will provide clean and renewable energy to the University of South Dakota (USD) and South Dakota State University (SDSU), which become the first universities in the Midwest to be powered with 100% renewable energy.

It also says:

The power produced will connect to the Western Area Power Administration (WAPA) transmission system and be purchased by Heartland through a long-term power purchase agreement.

In other words, the two universities are still getting their electricity from the same grid as everyone else. They can no more claim to be wind powered than any other customer on the system.

wind power, wind energy

Oil and coal/nuclear/wind: nothing to do with each other

The debate last night between Senators Obama and McCain illustrated a common laziness in lumping all energy together, failing to differentiate their different uses. Here are the relevant excerpts:

McCain: ... We have to have nuclear power. We have to stop sending $700 billion a year to countries that don't like us very much. It's wind, tide, solar, natural gas, nuclear, off-shore drilling, ...

Schieffer: ... Would each of you give us a number, a specific number of how much you believe we can reduce our foreign oil imports during your first term?

McCain: ... We can eliminate our dependence on foreign oil by building 45 new nuclear plants, power plants, right away. ... with nuclear power, with wind, tide, solar, natural gas, with development of flex fuel, hybrid, clean coal technology, clean coal technology is key ...

Obama: ... And I think that we should look at offshore drilling and implement it in a way that allows us to get some additional oil. But understand, we only have three to four percent of the world's oil reserves and we use 25 percent of the world's oil, which means that we can't drill our way out of the problem. That's why I've focused on putting resources into solar, wind, biodiesel, geothermal. ...

When you talk about nuclear, coal, and wind, you are talking exclusively about electrical energy. When you talk about oil, you're talking about transport and heating. Less than 3% of the electricity in the U.S. is produced from oil, and most of that is with the otherwise unusable sludge left over from gasoline refining.

Therefore, clean coal, nuclear, and wind have nothing to do with oil, imported or otherwise.

As for natural gas and wind, go here.

Wind energy myths on the grid

Michael Goggin has written a paper for the trade group American Wind Industry Association titled "20% Wind Energy by 2030: Wind, Backup Power, and Emissions". It is an attempt to claim -- in the face of conflicting evidence and reason -- that wind energy, even at substantial "penetration", does not require extra "backup" capacity and substantially reduces carbon emissions from other fuels.

The "no reduction in emissions" myth

Wind opponents sometimes argue that wind energy doesn't actually reduce the fuel use or harmful emissions of other power plants. On its face, this claim does not make sense: utility system operators must precisely balance the total supply of electricity with the total demand for electricity at all times, so the electricity produced by a wind plant must be matched by an equivalent decrease in electricity production at another plant.

The unstated part of that equation is that a decrease in electricity production does not necessarily mean an equivalent decrease in fuel use or emissions. In other words, a thermal plant simply diverts its steam past the turbines, but it doesn't stop creating steam. That is because it may take several hours to reheat. Plants that can switch on faster must use more fuel to do so (like stop-and-go city driving versus steady highway driving). Plants that can modulate their electricity production do so by operating at a lower efficiency, i.e., with more emissions.

• In 2007, wind energy in the U.S. reduced CO2 emissions by over 28 million tons, equivalent to taking almost 5 million cars off the road. On average, each Megawatt- hour (MWh) of wind energy -- the amount produced by two typical modern wind turbines in an average hour -- reduces CO2 emissions by 1,200 pounds.

There is no citation for this claim, because it based only on the above assumption that reduction of electricity production is the same as reduction of fuel use is the same as reduction of emissions. It is not based on actual data.

• The U.S. Department of Energy's (DOE) 20% Wind Energy by 2030 Technical Report calculated that obtaining 20% of our electricity from wind energy by 2030 would [emphasis added] cut cumulative CO2 emissions by over 7.6 billion tons.

• The DOE report found CO2 emissions would [emphasis added] be reduced by over 825 million tons in the year 2030 alone, an amount equal to 25% of all electric sector carbon dioxide emissions in that year -- the equivalent of taking 140 million cars off the road.

• The DOE study also found that wind energy would [emphasis added] cut the amount of natural gas used for electricity generation by 50% in 2030.

• A study by the grid operator in Texas found similar results, concluding that adding 3,000 megawatts (MW) of wind energy to the state's grid would [emphasis added] reduce CO2 emissions by about 5.5 million tons per year, sulfur dioxide emissions by about 4,000 tons per year, and nitrogen oxide emissions by about 2,000 tons per year.

• In regions where a large share of electricity comes from coal power, the emissions savings of wind energy can be [emphasis added] even larger. A DOE analysis found that Indiana could [emphasis added] reduce CO2 emissions by 3.1 million tons per year by adding 1,000 MW of wind power.

• The 30 MW Kaheawa wind plant in Hawaii directly offsets power from oil-burning power plants, reducing oil imports by almost 10 million gallons per year.

The company web site cited for this statement actually says: "Kaheawa Wind will [emphasis added] eliminate the use of over 236,000 barrels of oil or 69,000 tons of coal annually." (236,000 barrels = 9,912,000 gallons.) So again, offsetting the electricity production (which is rarely all oil or all coal based) is not the same as reducing fuel use or emissions, and thus it is not actual data cited but conjecture based on incorrect assumptions. In short, these are made-up numbers that have a shaky relationship with reality.

The "backup power" myth

Sometimes wind opponents claim that because wind energy output varies with the wind speed, wind plants require an equivalent amount of "backup power" provided by fossil fuel plants, negating the environmental and fuel savings benefits of wind energy. Understanding why this myth is false requires some explanation of how the electric utility system operates.

Overview of Power Grid Operations

System operators always maintain significant "operating reserves," typically equal to 5-7% or more of total generation. These reserves are used to deal with the rapid and unpredictable changes in electricity demand that occur as people turn appliances on and off, as well as the very large changes in electricity supply that can occur in a fraction of a second if a large power plant suffers an unexpected outage. Instead of backing up each power plant with a second power plant in case the first plant suddenly fails, grid operators pool reserves for the whole system to allow them to respond to a variety of potential unexpected events.

That is exactly why wind energy facilities can not claim to be replacing other sources. Because wind energy production is intermittent and highly variable -- and typically a small percentage of total generation -- the facilities are like "negative demand" to the grid, balanced by the operating reserves.

System operators use two main types of generation reserves: "spinning reserves," (regulation reserves plus contingency spinning reserves) which can be activated quickly to respond to abrupt changes in electricity supply and demand, and "non-spinning reserves," (including supplemental reserves) which are used to respond to slower changes. Spinning reserves are typically operating power plants that are held below their maximum output level so that they can rapidly increase or decrease their output as needed. Hydroelectric plants are typically the first choice of system operators for spinning reserves, because their output can be changed rapidly without any fuel use. When hydroelectric plants are not available, natural gas plants can also be used to provide spinning reserves because they can quickly increase and decrease their generation with only a slight loss of efficiency. Studies show that using natural gas plants or even coal plants as spinning reserves increases emissions and fuel use by only 0.5% to 1.5% above what it would be if the plants were generating power normally.

Non-spinning reserves are inactive power plants that can start up within a short period of time (typically 10-30 minutes) if needed. Hydroelectric plants are frequently the top choice for this type of reserve as well because of their speedy response capabilities, followed by natural gas plants. The vast majority of the time non-spinning reserves that are made available are not actually used, as they only operate if there is a large and unexpected change in electricity supply or demand. As a result, the emissions and fuel use of non-spinning reserves are very low, given that they only rarely run, the fact that hydroelectric plants (which have zero emissions and fuel use) often serve as non-spinning reserves, and the very modest efficiency penalty that applies when reserve natural gas plants actually operate.

There are two important things to note here. First, no-carbon hydro and low-carbon gas are the sources most likely to be used to balance the fluctuating feed from wind turbines. Yet, the industry always compares the equivalent carbon from coal, oil, or automobiles, when any carbon savings would actually be minimal. Second, since wind must be balanced as "negative demand", those other plants would have to be used more. In the case of gas, that means more carbon emissions, not less.

Accommodating Wind Energy

Fortunately, the same tools that utility system operators use every day to deal with variations in electricity supply and demand can readily be used to accommodate the variability of wind energy. In contrast to the rapid power fluctuations that occur when a large power plant suddenly experiences an outage or when millions of people turn on their air conditioners on a hot day, changes in the total energy output from wind turbines spread over a reasonably large area tend to occur very slowly.

While occasionally the wind may suddenly slow down at one location and cause the output from a single turbine to decrease, regions with high penetrations of wind energy tend to have hundreds or even thousands of turbines spread over hundreds of miles. As a result, it typically takes many minutes or even hours for the total wind energy output of a region to change significantly. This makes it relatively easy for utility system operators to accommodate these changes without relying on reserves. This task can be made even easier with the use of wind energy forecasting, which allows system operators to predict changes in wind output hours or even days in advance with a high degree of accuracy.

Moreover, changes in aggregate wind generation often cancel out opposite changes in electricity demand, so the increase in total variability caused by adding wind to the system is often very low. As a result, it is usually possible to add a significant amount of wind energy without causing a significant increase in the use of reserves, and even when large amounts of wind are added, the increase in the use of reserves is typically very small.

The conclusion that large amounts of wind energy can be added to the grid with only minimal increases in the use of reserves is supported by the experience of grid operators in European countries with large amounts of wind energy, as well as the results of a number of wind integration studies in the U.S.

Actually, the experience in Europe is the opposite of this claim. As wind "penetration" increases, the ability of existing reserves to balance it quickly diminishes and more excess capacity has to be added. See www.aweo.org/lowbenefit.html for a summary. The fact is that the wind doesn't always blow, even over a whole continent at the same time. Therefore, the grid has to be built as if the wind isn't there, because so often it won't be. And with the wind turbines added in, the grid needs even more capacity -- and more high-voltage interconnection lines -- to balance that energy.

The bottom line is that very little can be achieved with large-scale wind power on the grid. It simply adds expense and impacts without replacing other expenses or impacts to any degree that can justify it.

tags: wind power, wind energy, wind turbines, wind farms, environment, environmentalism

Buying the wrapper, claiming the cheese

Philadelphia Electric and Gas Company, or PECO, has signed up to buy 240,000 MWh of wind energy credits over the next 5 years from a facility in Illinois owned by Spain's Iberdrola.

Note that it's only the "credits", not the actual energy, that they'll be buying.

Yet, despite no change in the energy mix in Pennsylvania, despite the obvious fact that the wind energy is used by and sold to others, most likely in Illinois, the "credits" will allow PECO to claim that it is providing that same energy to its customers, as required by state law.

It should come as no surprise to learn that Enron invented this scam.

wind power, wind energy, green tags, environment, environmentalism

Cognitive dissonance: pro-wind, anti-development

As reported in the newspapers yesterday, Conservation Law Foundation and Vermont Public Interest Research Group have spoken up against governor Jim Douglas's energy policy.

They say, on the one hand, that Douglas's plan does not sufficiently protect the rural landscape from development and, on the other hand, that his plan does not sufficiently promote the development of industrial wind energy facilities, which by necessity must be sited in rural or wild areas.

These groups decry Douglas's effort to "simplify" the Act 250 environmental permitting process, but call for permanent clearcutting, blasting, and heavy-duty roads for wind energy facilities on otherwise protected ridgelines.

wind power, wind energy, wind turbines, wind farms, environment, environmentalism, Vermont

Wind energy for tax avoidance

"Before declaring itself bankrupt on 15 September, US investment bank Lehman Brothers was one of several major firms that invested in wind projects in exchange for the tax credit, which they used to reduce their federal tax bill."

--1 October 2008, Nature 455, 572-573

wind power, wind energy