Renewable electricity can be transformed into a substitute for natural gas. Until now, electricity was generated from gas. Now a German-Austrian research initia- tive wants to go in the opposite direction. In the future, the researchers and enterpreneurs would like to store surplus electricity – such as electricity from wind power or solar energy – as climate-neutral methane and store it in existing gas-storage facilities and the natural gas network.

Throughout the world, electricity generation is based more and more on wind and solar energy. So far, the missing link for integrating renewable energy into the electricity supply is a smart power-storage concept. When the wind is blowing powerfully, wind turbines generate more electricity than the power grid can absorb. Now German researchers have succeeded in storing renewable electricity as natural gas. They convert the electricity into synthetic natural gas with the aid of a new process. The process was developed by the Centre for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW), in cooperation with the Fraunhofer Institute for Wind Energy and Energy System Technology.

Currently, Solar Fuel Technology, the Austria-based partner company, is setting up the industrial implementation of the process. One advantage of the technology is that it can use the existing natural gas infrastructure. A demonstration system built on behalf of Solar Fuel in Stuttgart is already operating successfully. A substantially larger system – in the double-digit megawatt range – is planned to be launched by 2012.

For the first time, natural gas production combines the technology for hydrogen electrolysis with methanisation. “Our demonstration system splits water using surplus renewable energy using electrolysis. The result is hydrogen and oxygen,” explains Dr Michael Specht, of the ZSW. “A chemical reaction of hydrogen with carbon dioxide generates methane, and that is nothing other than natural gas produced synthetically.”

In developing this technology, the ZSW has been guided by two core issues: the storage systems that offer sufficient capacity for compensating fluctuating renewable energies that depend on the wind and weather, and storage systems that can be integrated into the existing infrastructure the easiest.

Integration into the infrastructure is simple: the natural gas substitute can be stored like conventional natural gas in the supply network, pipelines and storage systems in order to drive natural gas cars or fire natural gas heating systems.
The new technology aims at facilitating the integration of high shares of fluctuating power generation from renewable energies into the energy system. One goal is to structure the delivery of power from wind parks on a scheduled and regular basis. The new concept is a game changer and a new significant element for the integration of renewable energies into a sustainable energy system.

Starting in 2012, the Fraunhofer Institute of Wind Energy, the ZSW and Solar Fuel Technology intend to launch a system with a capacity of about 10 MW.