E.On: Storing Electricity in the Gas Grid

Countering the balancing problems of the grids, caused by the irregular electricity production from wind, E.On is constructing a pilot plant in Falkenhagen, near the eastern border of Germany. This plant will store wind energy as hydrogen gas, which can by mixed with natural gas in the gas grid. The plant will be operational from the third quarter of 2013.

Christian Folke and Stefan Rickelt presented the project during the Gas Week in the European Parliament. "It is difficult to store electricity in an efficient way," says Rickelt. "Our solution is to use the wind electricity to dissolve water by electrolysis in H2 and O2 and to inject the H2 in the gas grid. We can increase the level of H2 to 2% of the natural gas level. Even an higher amount is safe for most applications that use grid gas. But 2% is the safety limit for gas driven cars. We also do research the possible storage of H2 in the underground."

2%, it doesn’t seem to be very much. "But due to the extent of the gas grid, it is far enough to balance the irregular wind production." The hydrogen can be used as fuel just as the methane, but can also be methanised, reacting with CO2. "This way of methanisation –with CO2 from bio gas sources– has a 80% energetic efficiency." Just as methane, the stored H2 can be used as a fuel to generate power on moments there is no wind. And on other places, as the transport of gas is cheaper than the transport of electricity. Contrary to electricity, gas can easily be stored for later use. Storing the electric energy as gas will help to prevent the electricity grids to become overloaded.

The new system can become an incentive to increase the use of renewables and for the development of smart end user applications. "The storage of energy that we achieve this way can be a useful tool in arbitrage on the spot markets," says Folke. "It also reduces the opportunity costs, it avoids making extra expenses for adapting and enforcing the electricity grids to balance the wind production, as this is partly done by the gas grid.

In some countries, the same company is managing the electricity and the gas grid, but in other countries they are competitors. Stefan Rickelt: "To make our system work, a more intensive communication between the gas and electricity is necessary. In some causes existing laws have to be adapted."

Smart end user application preferable above smart grids

The balancing of the wind energy production by gas won't be only a grid matter. "A smart end user application can be a gas driven pump that produces electricity when there is no wind." But there still is a long way to go. "It will take a lot of time to develop a long living and affordable fuel cell for end users." But why should households and small companies invest in smart application if the smart grids are along their ways? "Smart grids are no complete solution for households. For a hotel it is ok that a washing machine starts working at 2h a.m., but would you like it to disturb your night? And what about the heating of dwellings? This requires energy on demand, not on the smartest moment."

There are more projects that pioneer this field. Recently, the Dutch Gasunie and the German cooperative Greenpeace Energy signed a cooperation agreement for wind energy storage by using the wind electricity to produce of hydrogen gas and inject this gas into Gasunie’s natural gas network in northern Germany. This project also will start in 2013.

By Koen Mortelmans