WALTHAM, Mass.--Five years ago, energy storage on the U.S. electric grid was almost nonexistent, but demonstration projects have shown that storage makes the grid more reliable and cleaner, according to a Department of Energy official.
Imre Gyuk, the program manager for energy storage research at the DOE, was the keynote speaker today at an IEEE conference on grid technologies where he said the grid storage industry is in the process of scaling up. Costs remain a barrier to putting more storage buffers onto the grid, but the question of costs may be a "red herring," he said.
Solar photovoltaic and wind power are not cheaper than fossil fuel power generation, yet a mandate for green technologies is bringing solar and wind onto the grid, he said.
"It's becoming quite clear that you can't have an appreciable penetration of photovoltaics and wind without the storage to smooth it out," Gyuk told CNET after his talk. "If you want a greener grid, you not only need renewable energy, you also need storage."
Some people argue that the grid can handle large amounts of renewable energy without storage, but places that already have high percentages of wind and solar power are running into limits, he said. In Texas, for example, a sudden drop-off in wind forced grid operators to temporarily cut power to some offices and factories, while parts of Hawaii are said to have put a pause on adding renewables in order to study grid stability.
The stimulus plan gave grid storage a significant shot in the arm, funding a number of demonstration projects for a variety of applications. The program is spending $185 million, which is matched with $585 million from the private sector.
The biggest technical challenge is to provide bulk storage to shore up wind and solar farms for several hours very cheaply, which a number of researchers are pursuing. Excel Energy tested a sodium sulfur battery at a wind farm in Minnesota, which provided good technical results, but the costs were very high.
By contrast, using lithium ion batteries or flywheels to provide quick bursts of power is already economical, said Gyuk. Because these systems provide and absorb power instantaneously, they are more effective than natural gas turbines and reduce carbon dioxide emissions between 70 percent and 80 percent, he said.
Because wind and solar are intermittent, there is a growing need for storage to maintain a steady frequency with short-term, high-power storage. The same technology can be used to maintain voltage, Gyuk said.
"We have gone from 100 kilowatt storage (for 15 minutes) to one megawatt and two megawatts, and now quite a number of planned 20 megawatt installations. I think we have shown this is the way to solve the problem and I expect it to become standard," he said.
There are a few projects where larger storage systems are used to shave peak demand, which could be cheaper and easier than bulking up the transmission and distribution system. A sodium sulfur battery at a substation in West Virginia stores energy at night and provides power during the grid during day, which is especially useful during hot days when demand is particularly high.
This system is not quite economical, but some technologies, including lead carbon batteries, are being developed to pursue this area, Gyuk said. Similarly, ramping up and smoothing wind and solar power needs more technical innovation and industry scale to bring down the cost of storage.
One of the barriers to larger adoption of grid storage is policy and utility regulations, which are mostly structured around investing in power generation. But storage is a necessary to scaling renewable power generation to 20 percent or 30 percent of all power generation on the U.S. grid, Gyuk said.
"Very roughly, I would be reasonably pleased if storage were about 20 percent of the renewable deployment to back it up," he said.