Power to Gas Technology
Power storage technology
By 2020, the share of electricity from wind and solar energy to increase to about five times today's production. Already, in some regions, surplus green electricity can not be fed into the power grid due to a lack of facilities for the storage of green energy.
On 30 October 2012, the Centre for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW) has opened a research facility with a electrical connection power of 250 kilowatts. The pilot plant, supported by the Federal Environment Ministry, converts green electricity, such as wind energy, into hydrogen and methane. With a possible methane production of up to 300 cubic meters per day, it is the largest facility of its kind in the world and ten times more powerful than the testing facility that had been installed three years before. This is a big step towards an industrial application of a new power storage technology.
Using the new system solution "Power to Gas" electricity rom renewable energy sources can be converted into hydrogen or synthetic natural gas and stored in the natural gas network. This would be a way to store large amounts of electricity from renewable energy sources in the long term. The conversion of electricity into synthetic natural gas takes place in two steps: First, hydrogen is produced by electrolysis, and then followed by methanation. The needed CO2 for methanation can be basically from fossil or renewable sources such as biogas plants, biomass gasification plants or sewage treatment plants. The gas can be stored almost indefinitely and transported over long distances.
Barriers and Drivers
The Renewable Energy Act has to be seen as a very important driver for the development of the above technology. The lack of storage technologies, in particular of green energy such as wind energy contributed to an increase in research. At the same time, a new renewable energy can be gained by application of the technology and further contribute to tax benefits and an improving image of the industry.
While the alkaline electrolysis has been used in large-scale commercial plants to produce hydrogen since the mid 20th Century, the PEM electrolysis is still in development and is only being used commercially in the low power range. The realisation of larger systems is currently limited due the size of the membrane electrodes. The high-temperature electrolysis, in particular the Solid Oxide Electrolysis Cell (SOEC), is currently at the stage of basic research.
The Deutsche Energie-Agentur (dena - "German Energy Agency") has set up the Power-to-Gas Strategy Platform in partnership with industry and research stakeholders to develop this new energy storage technology.
Extended power storage and improved technologies increase the options for the use of renewable energy enormously. Especially the automotive can benefit from power-to-gas, because the procedure also offers alternatives for future sustainable mobility.