Five Ways to Store Energy for the Smart Grid

Communications-enabled power grids and power meters–AKA “smart grids” and “smart meters”– have been getting lots of attention recently for their ability to accommodate the increasing amount of alternative energy sources coming online. The best way to make the most of, say, solar power, is to have a reliable way to store it when the sun goes down. That’s where grid-connected energy storage technology come in. Earth2Tech recently compiled a list of some of the best candidates for energy storage. Here are some of our favorites.

1. Fuel Cells Some car companies are still trying to push hydrogen fuel cells as the next big thing in energy-efficient cars, but electric vehicles are quickly overtaking them. Fuel cells have a much better chance of surviving in the energy storage market since they never get run down like batteries. The cells work by producing electricity through an electrochemical conversion, and can be quickly recharged by adding solution. Bloom Energy claims that it will have a large-scale fuel cell device for the smart grid ready in the next few years.

2. Lithium Ion Batteries Lithium-ion batteries can get run down over time, but they charge faster, are more lightweight, and have a higher energy density than lead acid batteries, which have long been the technology of choice for energy storage. A slew of companies are working on Li-ion technology, including A123 Systems and Altairnano.

3. Ultracapacitors Ultracapacitors are used in the auto industry to create short bursts of power and speed up charge times, and now capacitor producers think they could be useful in the smart grid as well. Companies like EEStor and Graphene energy are working on increasing ultracapacitor endurance, but the devices are still more expensive than batteries.

4. Compressed Air Compressed air technology is relatively self-explanatory: excess energy from power plants runs air compressors, which pump air into an underground cave. The air is stored under pressure, and when it’s released, it powers a turbine. It’s cheap and simple, but concerns about the environmental impact of storing compressed air underground have slowed its implementation. A few compressed air storage projects are already in the works, though, including one in Alabama and one in Germany.

5. Pumped Hydro Pumped hydro is already the most widespread energy storage technology, with about 90 GW of hydro storage in operation–that’s 3% of the worldwide generation capacity. Hydro technology works by pumping water from a low reservoir to a high reservoir and letting water move downhill when electricity is needed. It’s been used in Switzerland for a century, and probably isn’t going anywhere anytime soon.