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 lightning, 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 Storage, a division of the power company AES, 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.”
[Editor's note: An earlier version gave an incomplete name for the company that operates the 1-Megawatt battery in the Houston area. It is AES Energy Storage, rather than AES Energy.]