The process of storing wind and solar power as synthetic natural gas combines the technology for electrolysis with methanisation.
Passing the surplus energy generated by wind turbines or solar panels through water decomposes the water into oxygen and hydrogen.
2H2O → 2H2 + O2
One option after the electrolysis is to store the hydrogen for use in fuel cells. The storage, transportation, and combustion of hydrogen however raise several technical challenges and remain a costly option. The new technology follows a different approach of using a simple chemical reaction to produce methane out of hydrogen.
The pure oxygen generated out of the electrolysis is stored for combustion of the to-be-generated methane, to produce electricity at a later stage.
2. Sabatier Process:
The hydrogen resultant from the electrolysis process is subject to the sabatier process. Sabatier process is the reaction of hydrogen with carbon dioxide using a nickel catalyst at high temperature and pressure to methane and water.
CO2 + 4H2 → CH4 + 2H2O
The water resultant from the Sabatier process is recycled for further electrolysis, making the sourcing of pure water for this process a one-time affair.
A prototype of this system is already operational at Stuttgart, and a substantially larger system capable of processing 10 megawatts is poised to become operational by 2012.