“An electric vehicle is basically a battery with wheels.”
This weekend, I started writing a post discussing the lack of an economically viable large-scale energy storage technology that we can use in the absence of natural formations such as mountains (for pumped hydro storage) or large caverns (for compressed air energy storage). Often called the holy grail of the energy world, energy storage could enable large jumps in the sophistication of our electric grid and power generation infrastructure. In my research, I came across an article by former NY Times clean energy reporter and current writer for The Texas Tribune, Kate Galbraith, where she discusses large-scale energy storage in her piece titled Texas Tackles Electricity Storage. I thoroughly enjoyed reading it and wanted to share it here.
So, without further ado…
Texas Tackles Electricity Storage
by Kate Galbraith, The Texas Tribune
November 7, 2010
Dozens of gray compartments, lined neatly in rows, inhabit a box-like concrete building on the edge of the impoverished border town of Presidio. The only sound, aside from occasional clanking, is the whirring of air-conditioners to keep the compartments cool.
This $25 million contraption is the largest battery system in the United States — locals have dubbed it “BOB,” for Big Ole Battery. It began operating earlier this year, and it is the latest mark of the state’s interest in a nascent but rapidly evolving industry: the storage of electricity.
Storage is often referred to as the holy grail of energy technology, because it can modernize the grid by more efficiently matching people’s demand for power with the generation of electricity. A variety of early-stage technologies, from the Presidio battery (which can power the town for up to eight hours in the event of an outage) to super-conducting magnets to caverns that would store and release air compressed by electricity, are being studied around the state.
Texas is especially keen on storage because of the proliferation of wind turbines in West Texas. The machines generate the most power at night, when people are sleeping — so if their power could be stored for use during the day, it would significantly increase the usefulness of wind power, which currently accounts for about 6 percent of the state’s electricity generation.
“Storage has been an elusive goal of our industry for a long time,” says Barry Smitherman, the chairman of the Public Utility Commission, which regulates the operations of the state’s electric grid. “I think there’s a lot of great R&D being done in this area.”
The Presidio project does not back up the wind power, although future versions of the battery system could be used for such purposes. Instead, the 4-megawatt sodium-sulfur battery is supposed to help provide a steadier electricity supply for the town, which sits on the end of a 60-mile transmission line built in 1948. The line — still with many of the original wooden poles — often gets struck by lightening, causing frequent outages. A transmission line company, Electric Transmission Texas, plans to replace the line by 2012, but it installed the battery to keep the lights on in the meantime, as well as after the new line gets built.
The concept of electricity storage has been around for a long time. Decades ago, rural, off-grid ranchers could buy batteries to back up their small wind turbines (some old glass ones are on display at the American Wind Power Center in Lubbock). But they stored only enough electricity to power (partly) a single home — far less than the Presidio battery.
Additional battery projects, and potential projects, are sprinkled around Texas. AES Energy, a power company, began operating a 1-megawatt battery, a quarter of the capacity of Presidio’s, near its petroleum coke-fired power plant in the Houston area earlier this year. The company’s goal is to test how the technology will work with the grid system.
Duke Energy, a North Carolina-based electric company, expects final word around year’s end on whether it will receive the bulk of a $22 million federal grant to build batteries near a wind farm in Ector and Winkler counties. Yet another project, a multiyear study of a zinc-flow battery concept by the San Antonio utility CPS Energy, got canceled last year after the manufacturer of the not-yet-commercial technology “had some challenges,” says Lisa Lewis, a CPS Energy spokeswoman.
Other types of energy-storage experiments are also underway around the state. In August, a consortium including the University of Houston was awarded a $4.2 million grant from the Department of Energy to develop an energy storage system from superconducting magnets.
The wind-power arm of Shell and the power-generation company Luminant have been looking into the concept of “compressed air storage” to back up power from a wind farm in the Panhandle. Excess power — such as wind power generated at night — would compress air and pump it into a salt cavern or other suitable underground formation; the air could later be burned with natural gas and expand, generating electricity. So far, this technology has mainly been put to work in Alabama and Germany, but Allan Koenig, a Luminant spokesman, says the project “is moving,” although it is still in the development stage.
The main trouble with storage is that it’s expensive. The Presidio battery and accompanying substation cost $25 million to build, which amounts to about $6,000 for every resident of Presidio. Put another way, that is about $1 for every Texan.
Steven Stengel, a spokesman for NextEra Energy Resources, a major renewable energy developer, says that, generally speaking, the economics of battery storage — without significant grants or state or federal aid — are very difficult to make work for his company. NextEra is not currently planning investments in any storage projects, he says.
The plunge in natural gas prices over the past few years has also harmed storage economics.
Calvin Crowder, the president of Electric Transmission Texas, likens the enormous Presidio battery, which occupies an area the size of a big house, to the first digital computer built in Iowa in the 1930s. Subsequent computer technologies, he says, became “cheaper and more compact” — and the same should happen with batteries. The Presidio battery, which was made in Japan, required two dozen semi trucks to transport it from the port of Long Beach to Texas.
Who should pay for storage projects, and the associated matter of how they should be classified within the electric grid system, are important and complex policy questions that must soon be grappled with by the state. In July, the state’s grid operator, the Electric Reliability Council of Texas, convened the first meeting of a power storage working group; it will hold its fourth meeting on Nov. 8.
In the case of the Presidio battery, the Public Utility Commission in effect classified the battery as a form of transmission rather than power generation, meaning the cost will be shouldered by all rate-payers on the Texas grid.
Right now, Smitherman says, the commission is looking at each project on a case-by-case basis. He cautions against reading too much into the Presidio decision. But storage, he says, is “probably a longer-term policy issue that we need to tee up for discussion and resolution.”
Robert J. King, the president of Good Company Associates, an Austin-based energy-efficiency and renewables consulting firm, which has convened the Texas Energy Storage Alliance, says that uncertainty over how storage will be classified — and related questions about whether the range of benefits it provides could be captured — is making companies less likely to invest.
Another technology that holds some hope for storage is electric cars. Texas will see the arrival of hundreds or thousands of the vehicles in the next few months. The cars are expected to charge primarily at night, taking advantage of the night-time windiness. In theory, the electricity they have taken in could be sent back out to the grid in times of high need — especially late summer afternoons.
“An electric vehicle,” Smitherman says, “is basically a battery with wheels.”
The intermittency of many renewable energy fuel resources greatly inhibits the ability of these technologies to economically compete with non-renewable technologies like coal, natural gas, and nuclear power. In some ways, this is the opposite of the problem experienced by fossil fuel plants, which ramp their output up and down to meet demand that could jump up or drop down at any moment.
When the sun slips behind a cloud or dips below the horizon for the night, the solar panels you installed become interesting roofing tiles, instead of a valuable generation resource, sending you back to the fossil fuel-based grid for your energy. Because of our inability to economically store the energy that you captured with your panels during the day, their usefulness is limited to the periods of the day when the sun is shining.
The renewable energy panacea = economic, large-scale energy storage.
Researches throughout the world, including several here at the University of Texas, are working to figure out a way to store large amounts of energy for small amounts of money. One area of focus – material science, or more specifically the study of different materials to figure out how they can be used to economically store energy.
A recent discovery by MIT researchers, in partnership with colleagues at LLNL and UC Berkeley, might be the one we look back on and say “that was the moment that changed everything”… or maybe not… but either way, MIT’s determination of how a molecule called fulvalene diruthenium stores and releases heat on demand is pretty awesome.
According to a paper published on Oct. 20 in the journal Angewandte Chemie, fulvalene diruthenium actually undergoes a structural transformation when it absorbs sunlight, putting it into a higher-energy state where it can remain stable indefinitely. By adding a small amount of heat or a catalyst, the molecule “snaps” back to its original shape, releasing heat. Well… sorta…. According to Dr. Jeffrey Grossman, professor of power engineering in MIT’s Department of Materials Science and Engineering:
“It turns out there’s an intermediate step that plays a major role…that was unexpected.”
What is the importance of this unexpected step?
According to Grossman, this step results in the stability and reversibility that makes it possible to produce a “rechargeable heat battery” with this material. In this battery, we can store and release heat energy, bringing me back to solar energy.
Fulvalene diruthenium has the ability (in theory) to store heat up to 200 degrees C, which could be used directly to heat your home – kind of the opposite of the Ice Bear concept. So, what if we could store excess solar power during the day in portable, rechargeable batteries that we could run our cars with, power our lights, or even combine together until we have a big enough system to generate electricity for our street or town? This might be possible with MIT’s discovery.
But, before folks get too excited, I should note that these ruthenium is very expensive (and rare) and so is not itself a good candidate for cheap, abundant energy storage. But, understanding its behavior could lead to finding less rare materials that exhibit the same behavior. According to Grossman,
“[Ruthenium] is the wrong material, but it shows it can be done…It’s my firm belief that as we understand what makes this material tick, we’ll find that there will be other materials [that work the same way]“
To check out the journal article referenced in this post, check out the following reference:
Yosuke Kanai, Varadharajan Srinivasan, Steven K. Meier, K. Peter C. Vollhardt, Jeffrey C. Grossman. Mechanism of Thermal Reversal of the (Fulvalene)tetracarbonyldiruthenium Photoisomerization: Toward Molecular Solar-Thermal Energy Storage. Angewandte Chemie International Edition, 2010; DOI: 10.1002/anie.201002994
Thanks to Science Daily for bringing this paper to my attention. Very cool.