RE: [hreg] New battery packs powerful punch - USATODAY.com
The Smart grid newsletter covered this a bit.
Technologies and Capacities
Pumped hydro, which generates electricity by reversing water flow between reservoirs, is the most widespread energy storage system on power networks. With an efficiency rate of more than 70%, pumped storage accounts for over 90GW worldwide, according to the Electricity Storage Association (ESA).
Flywheel systems, which utilize a massive rotating cylinder, boast effective load following characteristics and a wide-range of short and long-term capabilities. Beacon Power has refined low-cost commercial flywheel designs for operation that could last up to several hours and experts estimate that forty 25kW (25kWh) wheels can efficiently store 1MW for one hour.
Super capacitors, or electrochemical capacitors, possess swift charge and discharge capabilities. More powerful than batteries, they can be cycled tens of thousands of times. Those with energy densities under 20kWh/m3 have been successfully developed, and work is underway to expand the effectiveness of larger units.
Flow batteries have low energy density, but they offer high capacity and independent power and energy ratings. Technologies in use include polysulfide bromide (PSB), vanadium redox (VRB), and zinc bromide (ZnBr). The Tennessee Valley Authority recently built a 12 MW, 120 MWh PSB storage plant. VRB installations offer up to 500kW, 10 hrs (5MWh). In 1991, Meidisha unveiled a 1MW/4MWh ZnBr battery and numerous multi-kWh ZnBr batteries have been built and tested over the years.
Vehicle-to-grid. The idea of using the batteries of electric vehicles as an energy storage resource -- a concept called Vehicle to Grid (V2G) -- is still in its infancy, but may have potential as a quick-response, high-value service to balance fluctuations in load. By connecting enough vehicles to the grid and transmitting power back and forth as needed, utilities could one day save billions per year, some experts predict.
According to Electricity Storage Association chairman Jim McDowall, installation of electricity storage is accelerating. Demonstrations are popping up around the country and confidence is building. Some of the benefits of electricity storage include:
· Protection from long outages, voltage sags, and surges
· Effective on-site generation for peak shaving customers (GridPoint has developed an energy management portal that informs customers about the most cost-effective time to run appliances and allows them to control energy consumption and costs.)
· Streamlining supply during peak periods by coalescing storage capabilities with renewable resources (Ice Energy has patented an energy storage module that can reduce building peak demand by up to 95 percent while providing 7.5 tons of cooling capacity for six continuous hours.)
· Complementary optimization of photovoltaic and wind-generated electricity
· Favorable life-cycle cost, including capital and installation cost, operation and maintenance cost, and disposal cost
· Versatility for transitioning to microgrids and decentralization
The storage industry has been working work with governments, regulators, utilities, and operators to address and attempt to overcome the challenges to the proliferation of electricity storage. Some of these include:
·A lack of government subsidies and incentives to encourage investment
·Regulatory constraints and limitations
·The uncertainty of selling electricity storage systems at a price that will allow both developers and customers to profit
·Political will (it will take time to influence decision-makers. Will the window of opportunity stay open long enough for that to happen?)