Photo by Steve Hoefer courtesy of Creative Commons.

Blowing away myths: Study says wind energy could be even more reliable than baseload power

What happens when the wind doesn’t blow?

That’s a question that wind power skeptics or critics frequently ask. While coal, nuclear and gas plants theoretically run uninterrupted whenever they are called upon, humans have no control over when wind turbines stop and start spinning. Some utility and power company officials say this is a reason that “reliable,” baseload power should be valued more than wind.

But in a report released Thursday and an accompanying webinar, experts with the American Wind Energy Association (AWEA) explained how wind can actually be seen as a more reliable source than conventional power plants — one that contributes to rather than inhibits the stability of the grid as a whole.

This is good news given that wind is considered a lynchpin of meeting the Environmental Protection Agency’s carbon reduction goals in the Clean Power Plan. No one disputes that wind is a zero-carbon and low-cost source of energy, but AWEA’s report underscores that it is also a reliable way to “keep the lights on.”

The truth about variability

Overwrought concerns about wind’s reliability often center on a fundamental misunderstanding of how the grid works, the report indicates. Since its inception more than a century ago, the grid has inherently handled a constant flux of supply and demand. All power sources involve some level of variability, and demand can vary greatly minute by minute. For example, AWEA points to energy demand during a 1990 World Cup game between England and Germany when demand spiked sharply during breaks, presumably as people quickly turned on appliances or electronics then turned them off once the game resumed.

Fluctuations in supply or demand from any given source do not matter to grid operators, said report author and AWEA research director Michael Goggin. All they care about is the total supply and demand on the grid at any given moment. As the AWEA report puts it, “The total variability is far less than the sum of its parts.”

“Grid operators only care about total variability on the power system,” Goggin said. “They don’t care what any one wind plant is doing or even what all wind plants are doing.”

Hence variations in the level of wind energy output are easily smoothed out over the grid as demand also rises and falls frequently and often unpredictably, and as output levels from other energy sources fluctuate. And the more wind power is added to the grid, the less variable wind energy as a whole becomes.

Wind output variations “are being canceled out by totally unrelated changes in supply and demand,” Goggin said. “What happens is you get a very smoothed-down profile across all these sources of variability.”

Goggin said that the variable output of wind is actually in some ways less problematic than variability from conventional power plants. That’s because changes in wind energy can be predicted in advance with considerable accuracy, whereas an outage at a power plant is usually sudden, unexpected and involves a more drastic reduction in power.

Modest reserves needed

Since wind’s variability is more predictable and involves a smaller amount of megawatts than the potential variability of power plants, less reserve electricity is needed on hand to guard against wind variability. The AWEA report cites data from Texas’ grid operator ERCOT showing that the need for wind reserves adds an extra four cents to utility bills, compared to 76 cents as a hedge against power plant outages.

ERCOT has more than 10,000 MW of capacity in the system, but only needs about 50 MW of fast-acting reserves on hand to compensate for wind variations, the AWEA report says. Midwestern grid operator MISO considers it needs “little to none” in the way of fast-acting reserves to protect against the variability of wind, the report says. PJM, the grid operator covering parts of Illinois and stretching east, has 3,350 MW of fast-acting reserves to guard against outages in baseload power plants. If PJM added a full 28,000 MW of new wind power, it would need only an additional 360 MW of fast-acting reserves.

The report notes that wind variability does increase the need for more slower-acting reserves, but those reserve sources of power are less expensive to have on hand than fast-acting reserves.

“Conventional power-plant failures most often happen in a fraction of a second with no warning; the variability of wind is both gradual and predictable,” Goggin said. “Gradual changes in wind output are relatively easy for grid operators to accommodate. On the other hand, rapid changes in electricity supply caused by traditional power plant failures require very fast-acting reserve generation. Twenty-four-seven, you don’t know when a traditional power plant will go down. With wind you can do forecasting, you know tomorrow between 2 or 3 p.m. there will be a reduction.”

Three prongs

The AWEA report indicates that focusing on the need for large amounts of “baseload” power is misleading. A better way to understand the system, AWEA says, is to break down the grid’s needs into three components: energy, capacity and flexibility. Energy is the actual megawatt hours of electricity flowing on the grid, capacity is the ability to generate more when needed, and flexibility is the ability to respond quickly to rises or dips in demand.

Wind is the lowest cost source of generation on the grid. And it could provide flexibility, although that would entail intentionally keeping wind resources offline so that they could be called on to quickly increase electricity availability when needed. Since wind is such a low-cost power source, it would generally not be economically wise to do this. Though as more wind power capacity is added, there’s greater chance that it would make sense to use some of it for flexibility.

“If you provide flexibility, you need to reduce the amount of energy you’re providing” during “normal” operations, Goggin said. “It’s not worth reducing low-cost resources to do so. Wind can provide flexibility but you would have to throw away zero-cost energy.”

With sophisticated electronics, wind turbines also have an impressive ability to control the voltage at which they feed power onto the grid and to “ride through” disturbances in the flow of electricity on the grid, Goggin said.

There has been much attention paid to efforts to develop more energy storage on the grid. This is considered an important way to increase the grid’s efficiency, reduce the need for baseload coal or nuclear plants and help shift the grid toward a more decentralized and nimble system. But Goggin said the idea that more energy storage is crucial to increasing wind capacity is a fallacy. The report notes that all power sources on the grid essentially act as storage, since taken together they compensate for the fluctuations or failings of other sources.

Demanding more storage on the grid specifically to accommodate wind farms would be akin to placing a battery between the grid and your house to make sure that your house draws the same amount of energy from the grid at all times, Goggin said.

“It would be highly inefficient and counterproductive to have a dedicated resource accommodating fluctuations in the electricity demand at your house, as nearly all of those changes are canceled out anyway by other changes on the aggregate grid,” the AWEA report says.

Wind on the rise

The report notes the strikingly large amounts of wind energy that are already being used in some states. In 2013, Iowa and South Dakota both got more than a quarter of their energy from wind and nine states got more than 12 percent. Texas got 10 percent of its energy from wind last year, an amount expected to increase to 15 or 20 percent by 2017.

Wind provided crucial power during the “polar vortex” last winter that saw coal plants shutting down and natural gas supplies interrupted as gas pipelines were overwhelmed delivering fuel for heat. Wind’s reliability during that crisis saved ratepayers in the PJM alone more than a billion dollars compared to the cost of generation that would have been tapped otherwise, AWEA says.

As wind energy continues to expand, arguments against reliance on wind energy and tax supports for wind farms are likely to continue. The report notes that no “rational voice” would advocate 100 percent of the nation’s or a region’s power come from wind energy — or any single source for that matter. Hence fears about the grid challenges that would arise with such reliance on wind represent a “strawman argument,” AWEA says.

“Wind energy is a very valuable contributor to a reliable and diverse and cost effective energy mix,” said Goggin. “Wind energy is ideally poised to provide valuable services grid operators need.”

12 thoughts on “Blowing away myths: Study says wind energy could be even more reliable than baseload power

  1. This is a particularly good report. I think we’re a long way from having it accepted by the industry, but this is a step. It helps a lot that they are using the more important values for generation in the strong wind states, rather than the peak numbers which a lot of people think are important.

    I like to tell people that as long as we have more natural gas capacity than wind capacity, we don’t need any storage. That’s important because it explains why there isn’t a lot of storage happening, even though we have a lot of good technologies that are affordable.

    The next five years are critical to a climate solution in the U.S., and what the U.S. does is critical globally. If we keep the momentum up (get wind construction back to where it was in 2012 and higher) we have a path to faster carbon reductions than most people are even talking about. Efficiency and PV are doing their part, although PV is still pretty small.

    I hope this report finds a good audience. I don’t know how much it will help in Ohio, where the problem is that the Republicans refuse to consider the actual costs and benefits of EE and RE. But it should be useful elsewhere.

  2. If wind is the lowest cost energy on the grid, why are they whining about the PTC credit taxpayer funded subsidy not being renewed? This article misleads readers to believe wind is so cheap, well it’s not. AWEA is the lobbying arm for major wind companies and they still say that wind power needs taxpayer money to compete with other sources of energy, even after receiving the PTC credit for over twenty years. On top of that they need states to mandate that ppl buy their power. Doesn’t sound so cheap to me.

  3. Kristi – who funded that report? I don’t see it disclosed anywhere.

  4. Thanks, Kristi. The funding stream question by Mr. Paulman is a red herring. Funding for a study is irrelevant if the facts add up.

  5. So the answer is you don’t know who funded it. That’s all I was asking.

  6. Variability is not the only factor. There is firm generation capacity, there is variable generation capacity, then there is dispatchable generation capacity. A nuke plant for example is firm, but not very dispatchable. It likes to run at full output and the termal intertia is so high that it is slow to respond to turn down or increase signals. A gas turbine is both firm and fairly flexible in its output, thus highly dispatchable. A pumped storage hydro unit is generally firm as long as there is enough rain and also highly dispatchable. Great for instant response to grid load following signals.

    Wind on the other hand is not very firm as there will be many more times when it either is not running at full output or is running during the off peak when it is not desired or even detrimental to the grid stability. Yet, if we agrigate many wind plants with other sources such as solar we get a reasonable steady source of mostly firm capacity in that it generates some power most of the time if not all the time. This is still not dispatchable in the classic sense. It cannot be easily ramped up or down with any degree of reliability. Still chunks of it can be turned off or on, which is in effect increasing or decreasing output. Blending in some gas turbine capacity, hydro or large scale energy storage with a portfolio of both wind and solar is now providing some range of smooth adjustable control of the output. While more complex than ramping a single plant, this hybrid conglomeration is nonetheless arriving at the same result within reason. So, when the grid is hard up enough for energy to choose to do so, wind blended with other sources such as solar and storage, as well as rapid response gas turbines can provide a much larger portion of the grid’s capacity with stability once it is designed into the system to do so. No one plant would accomplish such an ideal but the total package could do it reasonably well.

    This shortcoming of both wind and solar are one of the main obstacles to their being used to displace larger amounts of the fossil fuel generation. Price being a 2nd substantial obstacle. It is easy for grid operators to send signals to larger fossil plants to turn down but even they have sufficient thermal interia to prevent their immediate response. They rely on other smaller, faster generation sources such as pumped storage hydro to balance the grid and aid in load following response. If we had truly economical, reliable electricity storage, then we could get by with as much as 30% less total generation capacity in most regions simply by running all the generation at near full output during the off peak and storing the exess until it is needed the next day.

  7. Question: I am told that there was a study done in the late 1990’s that stated that coal-fired baseload generation was important to maintaining system stability in the Manitoba Hydro/MN/North and South Dakota area due to the long transmission lines between MH and the Twin Cities and also the Dakotas and the Twin Cities.

    Has anyone studied how to maintain system stability as coal’s share of the generating mix declines?

  8. Quote from the hidden costs of wind electricity: “Since wind generation reduces the average level of output of primary fossil plants, but
    reduces the need to keep those plants in operation by a far smaller amount, part of wind’s
    cost must be to pay for the appropriate portion of those plants’ costs of capital recovery,
    operations and maintenance. This is not a policy issue – it’s a matter of arithmetic.”

    Ehhhm, that IS a policy issue! What if a company decides to build a fossil plant, does it then have to compensate it’s competitors? How open is the market, are there agreements with existing plants on how much energy the are guaranteed to sell in each year of their operational life? Besides that, as our energy use is still rising wind energy can also be used in the form of added production, in which case these supposed costs are zero.

    To me the hidden-cost report suggests that the authors were not even slightly objective in calculating costs of wind and comparing it against costs of fossil/nuclear energy (no hidden costs there at all, ATI / E&E Legal Institute???????????).

    Kent Flanery: it is also possible to run a wind farm at a lower power setpoint, so production can be ramped-up if needed. This is done at Horns Rev offshore wind farm, see bottom half of page 3:

  9. It is important that we allow grid operators to speak for themselves, rather than to let a pack of vested interests speak for them. Grid stability is a matter of life and death, not an ideological issue. The risks of making bad choices are huge for everyone. The only ones who have benefited from all the bad choices are the developers of often-bankrupted and abandoned fields of unreliable energy.

  10. Interesting article.

    I don’t think it blows away any myths. Base load requirements are not mythical. Certainly there is a lot that can be done to ameliorate the issues surrounding wind farm power generation, but I remain skeptical as long as solid electrical energy storage remains just outside our grasp.

    I’m not a fan of wind farms. 🙂

    I wrote something up on this subject on my blog some years back:

    But that’s all beside the point. This was an informative article, and I found it quite telling that within a couple of days “Kristi” shows up and links a think tank generated bit of propaganda, and is then defended by “Mary”.

    But let’s look at the hard questions.
    Folks run nuclear up the flag pole. Absent massive subsidy, it doesn’t exist. Absent the Price–Anderson Nuclear Industries Indemnity Act, it doesn’t exist. Heck, the insurance industry doesn’t have a dog in this fight. They looked at the numbers for nukes, and said “No ‘eff’n way!” hence the government had to step in and foot the bill for the liability in order to give their cold-war step child a home.
    In a free market, there is no nuclear industry.

    Coal, absent massive government subsidy, in form of laws that protect the industry against all comers, in form of land laws that favor the industry, etc etc etc, there is no coal either.

    Same with Natural Gas.

    Add in the environmental cost, and all of this stuff is off the table.

    Nukes aren’t going away, we could, today, decide that they were a mistake and begin the process of decommissioning all the reactors out there, while we still have no clear idea what to do with all the material, and we’re still looking at a century’s worth of massive effort, and no one really has a clear idea of the cost. Too bad for us.

    Coal isn’t going away. Yes as coal plants pass their useful life, they get decommissioned, and getting one built isn’t the cake walk it once was, but we’re going to be burning coal for a long time yet.

    Folks have sold us this nat gas as a ‘bridge’ fuel.

    We’ll we better well be all set up on the other side of that bridge, and pretty soon too, as the whole debacle is finally being shown to be the massive investment fraud scam that many of us were yelling about as it took off.