E.On has started construction of a pilot power-to-gas project that will enable excess renewable energy to be stored in the gas network.

The German energy major says that the new plant will enable wind farms to continue operating even when their energy is not needed and its technology could therefore be an important addition to Germany’s energy network as it adds more renewable energy.

“If Germany expands the use of renewable energy sources in the coming years as planned, the power supply on very windy or sunny days will exceed demand more and more often, and to a growing extent,” said Klaus-Dieter Maubach, member of the E.On AG Board of Management responsible for technology and innovation. “This will increasingly bring the power grid to the limits of its capacity.

“E.On is therefore investing in the development of technologies to store large energy volumes. In this respect, power-to-gas is a promising solution for the future energy supply system.”

The pilot plant will be based on electrolysis technology, using wind energy to produce hydrogen that can be fed into the regional gas grid. E.On says that up to five per cent hydrogen can be added to the natural gas grid without any problems, and in the medium term experts expect up to 15 per cent could be added.

The large capacity of the gas grid makes power-to-gas technology particularly attractive, says E.On, although current regulations only allow for a small amount of hydrogen to be fed into the gas infrastructure.

The firm’s pilot plant will produce about 360 m³ of hydrogen per hour from 2013 onwards.

To expand the energy storage potential of the grid, hydrogen would need to be converted into synthetic gas, says E.On. Theoretically, this means that the entire storage capacity of the gas grid could be utilized.

E.On said in November 2011 that it would invest €5 million on the pilot plant and further research into the technology. One of the main aims of the pilot project is to improve the efficiency of the whole process, including the integration of wind power and the injection of hydrogen into the gas grid.