E.ON AG
12/01/2008  21:35 h
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Energy Storage

As renewables capacity increases, energy storage will become increasingly important. Fluctuations in output have made wind power particularly problematic for transmission system operators. Wind turbines can’t produce electricity if there’s no wind or if the wind blows so hard that it might damage the turbine. Conversely, turbines generate electricity and deliver it onto the system when it’s not needed due to low demand.

 

Pumped-storage hydroelectric plants, which can store electricity until it is needed, offer one solution. E.ON operates seven such plants in Germany. Unfortunately, there are very few economically viable sites remaining in Germany for more pumped-storage hydro capacity.

Compressed-Air Storage Plants
Another option is compressed-air storage which uses the energy storage in compressed air. During periods of low demand, excess electricity is transported to a storage site where it’s used to compress air in an underground cavern. When the demand for electricity is higher, the compressed air is released to drive a turbine that generates electricity or to turbo charge a gas turbine to boost its output.

 

E.ON is a leader in compressed-air storage technology. In Elsfleth-Huntorf, Germany, E.ON operates Europe’s only industrial-scale compressed-air storage power plant. During low-load periods, the 290 MW plant pumps air at 50 to 70 bars of pressure into two rock-salt caverns hollowed out when the plant was built in the 1920s. The only other similar facility is a 110 MW compressed-air storage plant in the United States.

 

The only drawback of these compressed-air storage power plants is that their efficiency is still below 55 percent because of the waste heat produced when air is compressed. E.ON is involved in two EU-funded projects to test processes that could enhance efficiency significantly.

©E.ON AG 2008