These are the real challenges for all of us when it comes to renewables. Sure PEI and other coastal areas get lots of wind, but there are really only a limited number of areas where the wind blows reliably strong enough to justify the tens of millions of dollars in investment in wind turbines. Solar production will work in areas with lots of sun and little rainfall, that's why you usually see the big arrays set up in deserts. (Using the sun to heat domestic hot water with a panel remains very doable everywhere).
But properly locating renewable projects is just the first challenge. The variability of renewable energy is a whole other issue. Even on PEI the wind blows strong enough to produce power efficiently about thirty percent of the time, and of course we never know when that will be. Electric customers however want to make toast, cook dinner, dry the clothes, whenever they want to, not just when the wind is blowing. That's why jurisdictions like Denmark and PEI (which relies more on wind than any other jurisdiction in North America) set upper limits for wind production (30% or so), because utilities have to have back-up generation to replace wind energy when it's calm, and the economics get way out of kilter trying to back-up much more than that. It's why PEI has been so insistent on getting some kind of regional power agreement in place (and get a stake in the new Newfoundland hydro-electric project), so that that back-up power is readily available, reasonably priced, and in the best of all worlds, renewable as well.
The systems operator (fancy name for the person sitting in New Brunswick who monitors who's producing and who's buying power) says there are moments (when the wind is blowing hard, and demand is light) when PEI IS supplying all its energy needs from wind, but it's very rare. (and check out Peter Rukavina's efforts to monitor this on his website: http://ruk.ca/content/monitoring-pei-wind-farms )
Storing renewable energy for later use is really the holy grail in the business. Summerside is taking small steps in that direction with the heaters it's offering homeowners that can take off-peak wind energy at night and store it for heat distribution during the day.
There are more ambitious storage projects on the go too. There's a very small electrolysis set-up at North Cape on PEI that produces hydrogen from wind energy for later burning, and the Wind Energy Institute of Canada, also in North Cape, is just embarking on storage research on a much larger scale. The wind turbines are just now being erected to provide the additional power. And then there's this story about using banks of lithium batteries to store power in West Virginia. I'm presenting two versions because it highlights the differences between publications, one very enthusiastic, the more mainstream a little more cautious. The bottom line: once storage becomes efficient and affordable, the possibility of a carbon neutral future, while enjoying the convenience of the grid, becomes so much more realistic.
http://www.grist.org/renewable-energy/2011-10-28-cool-energy-storage-projects-make-mockery-politician-pessimism
Cool energy-storage projects popping up; expect a lot more
by David Roberts • Oct. 28, 2011 •
Tracking the politics of clean energy can be a surreal and dispiriting experience. D.C. is so swamped in fossil-fuel money, fossil-fuel lobbyists, and fossil-fuel-owned pols that the conventional wisdom is absurdly pessimistic about clean energy: It's unreliable, it costs too much, it can never work, blah blah.
Meanwhile, out in the real world, costs are plunging and the intermittency problem (insofar as it's actually a problem and not a talking point of the fossil crew) is being solved.
There are two ways to solve it: one is connecting more renewables over a wide geographic area, which generally requires more transmission lines and grid upgrade (for intriguing news on that front, see here2); the other is adding energy storage, so solar and wind plants can provide power even when the sun isn't shining and the wind isn't blowing. That's what today's post is about.
I give you the Laurel Mountain wind farm, in West Virginia:
That's 61 1.6-MW wind turbines, for a total of 98 MW. And here is the massive bank of lithium-ion batteries that the wind farm will be connected to:
That's the world's largest lithium-ion battery farm -- 32 MW worth of storage, courtesy of A123 Systems3. The AES power company just announced yesterday that the wind/storage power system is up and running in full commercial operation. All told, it will feed 260,000 MWh a year into the power market along the Eastern seaboard. (For details, check out the full story4 at Forbes.)
It won't be the world's largest for long, though. Some time late next year, Duke Energy will switch on a 36-MW battery storage system, the world's (new) largest, attached to the company's 153-MW Notrees Windpower Project in west Texas. The storage system will use the proprietary dry-cell battery technology of a very cool company called Xtreme Power6. The systems contain both dry-cell batteries and sophisticated power control technology, so they not only store power, they enhance grid reliability. As the CEO explained it to me a few years back, the storage system basically presents itself to the grid like a highly dispatchable power plant.
The energy-storage industry is still in its infancy7. Over 99 percent of the energy storage installed globally is made up of pumped hydro, whereby surplus power is used to pump water uphill and then the water flows down, turning turbines, when spare power is needed. That's a solid, reliable way of doing things, but its efficiency isn't that great and it faces some geographic limitations. Tons of new and alternative technologies are coming online as we speak, though: compressed air, flywheels, molten salt, and several different kinds of batteries, including the distributed batteries in electric vehicles.
Discussions on storage often end with, "for now it's too expensive." In most cases, that's true, but it's misleading to treat the affordability question as though it's a binary switch, as though someday storage will flip from being too expensive to affordable. Right now, some forms of storage are cost-effective in some applications given some markets and regulations and some accounting methods. (See above!)
What will happen is, that small pool of affordable storage applications will grow larger, not only because the technology will advance but because accounting methods will change (full lifecycle cost accounting over extended time periods makes storage look a lot better), regulations will change, markets will change, and the engineering culture inside power utilities will change.
All this will happen, I predict, much faster than even the most optimistic projections now have it. Even as a kind of resigned fatalism-bordering-on-nihilism has gripped the political conversation, out in the world, clever people are doing ambitious, exciting things. Don't let politics fool you: This is an amazing time to be involved in clean energy.
http://www.nytimes.com/2011/10/29/science/earth/batteries-on-a-wind-farm-help-control-power-output.html?hpw
October 28, 2011
Batteries at a Wind Farm Help Control Output
By MATTHEW L. WALD
ELKINS, W.Va. — Another wind farm opened on another windy ridge in West Virginia this week, 61 turbines stretched across 12 miles, generating up to 98 megawatts of electricity. But the novel element is a cluster of big steel boxes in the middle, the largest battery installation attached to the power grid in the continental United States.
The purpose of the 1.3 million batteries is to tame the wind, but only slightly, according to the AES Corporation of Arlington, Va., which developed both the wind farm, known as Laurel Mountain, and the battery project.
The installation is far too small to store a night’s wind production and give it back during the day when it is needed, or to supply power when the wind farm is calm for more than a few minutes. Instead, AES says, the battery will be a shock absorber of sorts, making variations in wind energy production a little less jagged and the farm’s output more useful to the grid.
The technology is young, and the finances are challenging. But the task of smoothing output, and the more ambitious one of storing many hours of electricity generated by wind production, seem likely to become ever more important as states require that a rising percentage of their electricity come from renewable sources.
The 13-state regional power grid that includes West Virginia, for example, has a capacity of 4,800 megawatts of electricity from the wind. But that number would grow eightfold if all of the states involved reached their renewable targets.
Power systems have always faced fluctuations in demand. As they incorporate more wind into the mix, they will have to cope with supply fluctuations as well.
Predicting wind output can be a challenge. “If you blow your forecast, you’re in a heap of hurt,” said one storage expert, David L. Hawkins, a senior consultant at KEMA, a consulting firm.
Other power sources, mostly natural gas plants, can be called on as replacements, but such plants take longer to ramp up — or ramp down — than a wind farm or a field of solar panels, a problem that is becoming more widely recognized across the country. This year, two big manufacturers of gas-fired power plants, Siemens and General Electric, promoted new models that could change output faster, but system operators say that even these may not be nimble enough.
“That’s the challenge you have in running the power system,” said Mark T. Osborn, an executive at Portland General Electric in Oregon who is working on a similar installation in the Pacific Northwest. “Storage has been thought about for years, but the costs have always been too high. Now when you’re trying to integrate more renewable resources, storage becomes more necessary.”
Already, in periods of low energy demand on windy nights, wind production is so strong that electricity prices on the grid can decline to zero or even go negative. When they are negative, grid operators bill wind suppliers to put power into the system.
In theory, the assumption would be that the operators of the batteries here would charge them at night and release the energy during peak periods in the daytime.
But the batteries are so small — somewhere between C and D batteries in size — that the wind farm, at full power, would fully charge them in about 15 minutes. Even at a peak demand time, the energy stored would only be worth a few hundred dollars.
The economics can be likened to storing tap water in a solid gold vessel. While AES did not disclose the price of the wind farm or the battery installation, a company executive gave a nod when presented with an industry estimate that the batteries and related electronics cost in the range of $25 million. The supplier, A123 Systems, of Westborough, Mass., says future installations will use batteries developed for electric cars and will cost less.
Yet the batteries perform two other tasks that the company hopes will turn a profit and pave the way for even bigger projects.
Rather than store power on a daily basis, said John M. Zahurancik, vice president for operations and deployment at AES Energy Storage, the installation will earn its keep by storing energy for minutes at a time, over and over again.
In the space of an hour, the output from the wind farm could go from 98 megawatts to zero. “In any short couple-minute interval, it could vary 20 or 30 or 40 percent,” Mr. Zahurancik said.
The batteries will smooth out the changes so the rest of the grid can catch up, he said, making the electricity sold more valuable.
The battery installation will also assist with a different kind of grid stabilization: trying to keep the alternating current system correctly synchronized. To keep the system as close to 60 cycles as possible, the regional grid operator, the PJM Interconnection, sends a signal every four seconds, asking for power to be added or withdrawn.
Experts foresee other roles as the grid evolves. For example, PJM operates a real-time market in which electricity is priced in five-minute blocks. At a given location, the price from one block to the next can vary significantly.
Mr. Hawkins of Kema said that a big battery array could make money in that market.
“It’s kind of like being a day trader on Wall Street,” he said. “If you see a $30 price spread, you can make some interesting trades doing it over and over in the course of a day.”
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