But a handful of companies around the region are designing new kinds of energy storage systems that could provide a different answer, perhaps helping to speed the spread of renewable power. Using large-scale battery banks or serpentine pipes filled with compressed air, they hope to capture the power produced by a wind turbine or solar panel and release it to the electrical grid when it is most needed. Both approaches would have zero emissions.
“The challenge for people developing renewable power projects is that you get a low price if you can only provide sporadic power,’’ explains Rob Day, an investor at Black Coral Capital in Boston who focuses on the energy industry. “If you can deliver a consistent load of power, you can get perhaps double the price, so developers might be willing to invest in additional equipment.’’
The caveat, though, is that energy storage systems need to be efficient, reliable, low-maintenance, and low-cost. The two main approaches - batteries and compressed air - “are making good technical progress,’’ says Day, “but neither is ready for prime time yet.’’
In New Hampshire, not far from Seabrook Nuclear Power Station, a start-up called SustainX is designing and testing compressed air storage systems. Founder Dax Kepshire says the technology could store power from any sort of generating facility. Electricity from the facility powers an electric motor that pulls air into a maze of pipes and compresses it to about 3,000 pounds per square inch. (A typical car tire is inflated to about 30 pounds per square inch.) “When you reverse the process, uncompressing the air drives the same electric motor, which functions as a generator,’’ Kepshire says.
One challenge, however, is that when you compress any gas (oxygen, for instance), it gets hot, and when you expand it gets cold. To keep temperatures constant, SustainX injects a fine mist of water into the system, which captures heat in one phase and then gives it back in another, according to Kepshire. Avoiding temperature extremes will ensure that the system has a long life, SustainX believes.
