How A Houston Company Could Store Electricity In The Ground

Texas may someday soon have a big electrical problem. Not a shortage of electricity. Just the opposite: too much electricity at the wrong time. Could it be “stored” in underground caverns?

By Dave FehlingNovember 16, 2016 9:30 am| , , , ,

From Houston Public Media

In West Texas, energy companies have been erecting giant wind turbines by the thousands. Government forecasts say thousands more could be built in coming decades. But even now, so many wind turbines are generating so much electricity that companies have to literally give it away at night when the wind blows but when electricity demand is very low.

“People are looking at how to use that West Texas wind and better match the supply of wind to periods of high demand,” says Paul Denholm, an analyst at the National Renewable Energy Lab in Colorado.

Denholm told us that people in the energy business are looking at a way to store all that electricity made at night so they can then sell it during the day when demand and prices are far higher.

But how do you store electricity overnight that would be enough to power thousands of homes? Simple, just dig a very big hole in the ground.

“Compressed air energy storage does need an appropriate big hole in the ground,” says Denholm.

Compressed Air Energy Storage (CAES) uses that electricity to run a giant air compressor. At night, the compressor injects air into a huge, airtight underground cavern. Then, during the day, the high-pressure air is released to run a turbine which generates electricity. Presto, the stored compressed air has been turned back into electricity.

But first, where in the world could you find a suitable cavern to store all that air?

“There are very few places in the U.S. where we have that. In fact the Gulf Coast, Texas, Alabama; that’s the only place we have that,” says Denholm.

Texas has massive underground deposits of solid salt called salt domes. They can be hollowed out to make caverns. Around Houston the caverns are used to store natural gas and oil and petroleum products.

But a Houston company has found one salt dome in Anderson County (about a hundred miles south of Dallas) that it says could be the first in Texas, and only the second in the U.S. to be used as a way to store electricity.

“The actual cavern we have is [the] height of the Empire State Building,” says Shawn Patterson,  chief financial officer with a company called APEX CAES.

“So we have all of our permits, we’re construction ready. We’re seeking financing to close the project and we think that could be forthcoming the middle of next year,” says Patterson.

One of those permits is an agreement with ERCOT — the agency that manages the Texas power grid— to allow  operation to begin in 2018. By that time, there could be even more electricity being made by wind and also solar.

In fact, would this project even be considered if Texas were not the country’s leader in electricity made from wind ?

“No, we think wind is the real driver for the project,” says Patterson.

Will it succeed? The analyst, Paul Denholm, says: “I think the increase in wind and solar definitely increase the economic potential. It’s really going to come down to the dollars and cents and the cost of this particular project.“

That cost could be a couple hundred million dollars. But Texas makes more electricity than any other state. And with an increasing amount being made from an inconsistent source — wind — the salt domes that are particular to Texas could be a way to store that energy for when it’s needed most.