Saturday, June 16, 2007

The Wind Power Storage Myth

It seems so intuitive, so right: everyone knows from direct experience that the wind is variable, and so it really can't be a serious energy source without some form of storage, can it?

Of all of the myths about wind power (of which anti-wind folks, with their covert allies and backers in competing energy industries, are inventing new, creative additions daily), this one is probably the oldest and most difficult to stamp out. Only today, many news sources carried a summary by Reuters energy reporter Timothy Gardner of a new book, Lights Out, by Jason Makansi. The summary includes the following quote:

Wind power won't take off unless there's more investment in how to store the energy, according to Makansi.


I suppose it all depends on what you mean by "take off." Wind power generates a bit less than 1% of U.S. electricity today (it should cross the 1% line by the end of this year), so for me, "taking off" would mean getting to 10% or 20%, in the general range that natural gas (17%) and nuclear power (20%) generate today. Maybe Makansi has something higher in mind--setting an unrealistic bar is one of the easiest ways to belittle a new technology. But anyway . . .

Storage is not, repeat not, required for a significant expansion of wind power from its current level to a level 10 or 20 times as great, at which point it will be a major contributor to U.S. electricity supply. Variability of wind is best addressed by utilities in the same way they address variability in current generation and load, which is to control certain resources to match aggregate load. All existing resources occasionally shut down with no notice, and these forced outages require backup and reserves. Wind is only different in that its output changes are more gradual and can be greater in magnitude, and that is not necessarily more difficult to manage. Storage might be cost-effective for power system operators some day in the future, but is generally not cost-effective today, and is not required, either for conventional resources or for wind. As the U.S. Department of Energy puts it in an excellent short publication, Wind Energy Myths:

The utility system is . . . designed to accommodate load fluctuations, which occur continuously. This feature also facilitates accommodation of wind plant output fluctuations. In Denmark, Northern Germany, and parts of Spain, wind supplies 20% to 40% of electric loads without sacrificing reliability. When wind is added to a utility system, no new backup is required to maintain system reliability.


Ironically, Makansi's main theme is to flog something that is perfectly true: the fact that America's electricity transmission system is aging and inadequate and in desperate need of an overhaul. This is ironic because more transmission is exactly what is needed for the power system to handle more wind--the wind is always blowing somewhere, so shipping the wind-generated electricity from where it is being produced to where it can be used is key to using it as cheaply and effectively as possible.

Those who wish to dig more deeply into this topic will find an excellent collection of resources at the Utility Wind Integration Group site.

This is not to say that more storage would be bad: one of the truly exciting possibilities on the horizon is plug-in hybrid autos, which would allow wind power not just to supply electricity, but to replace a sizable chunk of the oil our nation uses for transportation. But we don't need more storage to use much more wind for electricity generation. Period.

Regards,
Tom

11 comments:

Manu Sharma said...

This is indeed a widespread belief. I ran across a Monbiot article referring to the same limitation.

Thanks for pointing to the Utility Wind Integration Group site. I've been trying to understand this too and wish to learn more.

Tom Gray said...

Thanks for visiting and commenting, Manu. The UWIG site has all of the resources and references. Basically, what this issue boils down to in practice is that there is usually a cheaper alternative to storage, whether it is accommodating wind's variability with existing flexible generation resources (hydro or gas) or strengthening transmission connections with neighboring utility control areas.

Regards,
Tom

Manu Sharma said...

Tom, after going through UWIG presentation on Grid Impacts of Wind Power Variability, it appears that Monbiot is correct to say that "if we switched our entire electricity-generating network over to variable sources of renewable power, there would be a power cut whenever the wind or waves dropped."

The presentation makes it clear that the impact on grid and additional costs to manage it depend directly upon the level of penetration of wind power. The greater the penetration, the bigger the impact and tougher it is to manage.

Although 15-20% penetration can be managed but anything beyond that is up for question. Therefore, if we're talking about renewable sources to contribute over 50% of the energy mix by 2050, energy storage has to be very much part of the picture. I wouldn't call it a myth.

Lets just hope that new and inexpensive storage technologies will become feasible in the coming decades. Here's an excellent listing of existing large-scale energy storage technologies and their cost comparison.

Tom Gray said...

Monbiot is correct if the reference is as you have described it, but the problem is that the fact that you'd need storage with 100% wind is being used by wind opponents to cast aspersions on the idea of 10% or 20%--or indeed, ANY more--wind. Please read what I said again carefully. Within the context of 10% or 20% wind (a huge increase from where we are now), storage is not an urgent need and the idea that it is--is a myth.

Thanks for providing the extra info on storage technologies.

Regards,
Tom

Manu Sharma said...

Yes, if UWIG study is to be believed, there's no immediate requirement of storage at places that have other "flexible" sources of power such as hydro and gas. Some countries such as Australia which has massive coal reserves and no substantial large hydro capacity might face problem but for most countries there's no immediate requirement. It would take a long time for wind power to reach 10-20% penetration.

Manu Sharma said...

"Within the context of 10% or 20% wind, storage is not an urgent need."

That's true. If the UWIG study is to be believed, as long as you have "flexible" sources of generation such as Hydro and Gas, the additional costs to manage grid connectivity is less than that of storage.

But it is significant nevertheless and it's important to have those flexible sources.

Tom Gray said...

. . . or to broaden connections with neighboring utility systems that do have them.

Regards,
Tom

Robin Nixon said...

There's also now 'Dispatchable Wind' which stores excess wind power underground in pressurised air tanks and releases it on demand to compressed air turbines.

http://robinnixon.com/blog/2007/07/04/dispatchable-wind-wind-energy-on-demand/

Pearl Street said...

Makansi Responds:
I have responded to Mr. Gray in my own blog, http://pearlstreetpower.blogspot.com/, but in the interest of full disclosure and open dialogue, I’m including that posting here as well:


After returning from a long and much-needed vacation, it came to my attention that Mr. Tom Gray, Communications Director for the American Wind Energy Association, read the Reuters review of my latest book, Lights Out, and decided to take issue with my position on linking wind energy to electricity storage. It seems clear that Mr. Gray has not read the book, but has instead staked out his position based on the review alone.

I suggest that Mr. Gray should 1) read the book, and 2) relax. In fact, he can rest easy in the fact that Lights Out does not bash wind or renewables at all and his intimation that I am an just another of the "anti-wind folks," whose "covert allies and backers in competing energy industries, are inventing new, creative additions [myths] daily" is simply, well, wrong. (Is this some sort of vast, engineering conspiracy he's referring to?)

In fact, should Mr. Gray read the book, he would find that it supports low or no-carbon solutions to the hilt. Mr. Gray should take off his ideological, one solution fits all, glasses, and look more closely at the full range of challenges and complexities inherent in the electricity generation industry.

Instead Mr. Gray is busy asserting that opponents to wind are actively promoting myths denouncing the viability of wind energy. Indeed, while Mr. Gray spreads the idea that "wind is variable, and so it really can't be a serious energy source without some form of storage" is "the oldest and most difficult [myth] to stamp out," experts across the industry are working hard to create an environment in which both physics and market forces converge to better integrate wind energy into the grid so that wind can truly become a major contributor to our energy supply.

Perhaps we would all take him more seriously should he admit that one major reason why wind energy proponents refuse to acknowledge the need for storage is that, without it, the wind industry will sell a whole lot more turbines, especially under current production tax credit subsidies and renewable portfolio mandates.

But, back to his criticism of my position on wind and storage. First of all, I don’t think I used the phrase “take off,” or if I did, it’s been taken out of context. That belongs to the journalist. (As you can see in the Reuters piece, it's not a direct quote.) In fact, I know that wind energy is taking off. It is approaching 1 percent of all the electricity generated in the US. (Coal is at 50%, nukes at about 20%, natural gas at 20%, hydro about 8.5%, wind around 1%, and biomass, solar, and geothermal make up the balance.) I know that wind is on a roll. And, I know that at percentages like this, the variable nature of wind isn't a big concern. But if the idea is for wind to become a significant contributor to our energy supply, then the fluctuations are a problem and they are different from the fluctuations imposed by other generating plants. Most of the latter are planned and can be moderated ahead of time. while wind speeds are varying all the time.

Over the last 30 or so years, I’ve sat in many technical sessions about wind and the grid impacts. Wind energy ideologues (yes, there are ideologues on all sides of an issue) refuse to admit there are any impacts, or if there are, they are someone else’s problem to solve and pay for. However, those who own, operate, and maintain the grid, continue to insist that these impacts are real, that better solutions are necessary, and the cost/pain must be shared by all. Storage is one solution; yes, it can be expensive, but there are multiple value buckets, which I point out in the book. There are other solutions for moderating the wind’s variability as well, some of which represent additions to the wind turbine system or the substation to which the turbines are connected. These also add cost. It is worth noting that all of the turbine vendors are working to solve the problem of grid impacts. We can kid ourselves politically and from a self-interest point of view that the impact is a red herring, but technologically, this is real stuff.

Electricity consumers will pay the bill either way. What I suggest in the book is that, as an industry, we should seek the best technological and the lowest cost solutions for all. It does no one any good--and indeed only impedes cooperation and progress--when we adhere to ideological positions that one thing is good and another thing is bad. When one understands the other values that storage brings to the system, I think ultimately coupling renewables with storage is the best way to maximize the fraction of renewables on the system at a reasonable cost.

One more thing...it is interesting to note that on his own blog, Mr. Gray does eventually admit that when wind does become a major contributor to the grid, variability will be an issue. Why not tackle that issue now and create the most favorable environment for wind energy's future growth and development?

Dave Gore said...

If off the grid, in areas with a low water table (e.g., 300 feet down), it seems windmill energy could be stored by pumping water up into a pond when the wind blows, then letting it run back down the well through a submersible generator when power is needed.

Tom Gray said...

Yes, there are many approaches to storage. This one sounds like a variant on pumped storage, which is used today on a much larger scale. The question is always one of cost. As I attempted to explain in the main article, there are usually cheaper alternatives, and the use of wind could expand dramatically without the addition of storage.

Regards,
Tom