Status of Solar Energy Storage Capacity in U.S.

While Germany Explores Energy Storage Technologies at Breakneck Speeds, the US Isn’t Far Behind

Germany could be using 60 percent renewables if the right storage tech were in place. Startling as this announcement seems, the US is not as far behind as people think.

The U.S. is surging ahead in terms of adopting battery storage. In 2013-2014, U.S. companies installed, or were in the process of installing more than 300 MW of energy storage capacity. The largest is Southern California Edison’s Tehachapi Energy Storage Project. It is a 8-MW system capable of supplying 32 megawatt-hours of electricity to the grid.

The aging U.S. infrastructure is a problem when it comes to grid stability. Many of the distribution feeders are nearing the end of their expected useful life. They are fairly weak and not equipped to handle a large influx of intermittent energy.

U.S. usually uses only about half of its electrical generation capacity. The peak times only amount to 2 or 3 percent of the year. Very expensive equipment is being purchased to meet that peak demand and it is not used very often.

Instead of simply replacing the old grid with a new one, U.S. utilities should ask questions like: Where will we get the most value for our investments? What value do we place on getting a more resilient, more reliable grid? How important is it to have a grid that utilizes more renewable resources?  Do we want to lengthen the life of existing resources?

All of these things can be done better. Not by spending another dollar on hardware equipment, but by spending another 10 cents on software and algorithms.

Like the US, Germany’s real contribution is software. Its battery plant focuses on 15-minute applications, the maximum allowed under “regulations/market design.”

Energy storage is by far one of the fastest resources, capable of handling the increase or decrease of the required frequency almost instantaneously.

Their weakness is duration. They become energy limited if forced to carry loads over an extended time. Utilities use a progression of plants for providing spinning reserve, primary and secondary reserves.

It is not economically feasible to insert more than 75 percent of renewable content into the grid, using battery packs. Germanys’ goal is 60 percent annually. This means some conventional plants will have to remain online until a new technology is developed.

Can the US Build a Green Grid?

Regardless of whether solution works in Germany, or not, it is not applicable to the U.S.

“We couldn’t do that right now because we are not generating enough renewable energy to store, even if we had the storage available,” said Allan Hoffman, a former senior executive with the U.S. Department of Energy.

Hoffman believes the U.S. will eventually use 80 percent renewable energy, and referred to the National Renewable Energy Laboratory’s Renewable Electricity Futures Study:

Renewable electricity generation from technologies that are commercially available today, in combination with a more flexible electric system, is more than adequate to supply 80 percent of total U.S. electricity generation in 2050 while meeting electricity demand on an hourly basis in every region of the country.