Audi is building a plant that will use solar and wind power to make methane from water and carbon dioxide. The plant, which will use technology developed by Stuttgart, Germany-based SolarFuel, is scheduled to start operation later this year. It will produce enough methane to power 1,500 of Audi’s new natural-gas vehicles, which also go on sale this year.
SolarFuel’s process uses excess renewable energy generated as a result of Germany’s push to reduce greenhouse-gas emissions. There’s now so much renewable energy in Germany that supply sometimes exceeds demand—such as when the wind is blowing late at night. That power could be cheap enough to make methane from water and carbon dioxide, even though the process for doing so is inefficient.
SolarFuel says its approach may be a solution to one of the biggest challenges with renewable energy—its variability. Methane, which can be stored in existing natural-gas storage facilities, provides a convenient, long-term option for storing the energy.