Methane as Battery

Audi appears to be taking the idea of carbon neutral transportation seriously. Along the way they have identified a new and plausible way to store renewable energy: methane whose carbon source is ambient CO2.

The Audi e-gas facility that is currently being built in Werlte in the Emsland region will be operated with renewable electricity (e.g. from wind energy and solar energy). Expansion into the area of renewable energies is increasing the share of volatile energy sources – sometimes there is a surplus of electricity while at other times a shortage exists. The facility with its electrical power consumption of about 6,000 kW will preferably draw electricity whenever there is an electrical surplus. Then the facility could serve as a means for long-term storage of renewable energies, and this would solve one of the central problems of the transition to new energy sources.

combining hydrogen with CO2 in a methanation system (downstream of electrolysis) to synthesize renewable methane – Audi e-gas. This natural gas substitute can be locally fed into the natural gas network to store the energy. The Audi e-gas facility in Werlte, which Audi is now constructing with system builder SolarFuel, will be the world’s first facility to convert renewable electricity and CO2 into a synthetic natural gas that can be fed into the natural gas network on an industrial scale.

And more power to ’em I say. The rest of the article is equally interesting.


  1. Electrolysis isn't efficient enough to make really good use of "extra" renewable energy. I suppose if you have a vast wind farm and stronger winds than you need, sure, this is better than throttling down.

  2. Electrolysis (H2 production) for energy storage has been proposed before. The innovation here is taking it an extra step and making methane from that hydrogen, rather than storing it as H2. If the H2 to CH4 process is efficient enough, the extra conversion loss will be more than offset by the advantages of using existing natural gas infrastructure.

    As for then using the natural gas as a transport fuel in personal vehicles... I'm not such a big fan. CNG has some really good niche uses (delivery trucks, buses), but has some similar drawbacks to electric cars (range). LNG has potential for heavy trucks and trains. I see the near to mid future car market belonging to electrics and diesels.

    I think AUDI should be cautiously applauded for what they're doing; they're grappling with the problem, rather than paying people to tell them there isn't one.

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  4. I knew there were cases of "too much wind", but I didn't realize we were already at the point of that large a transient excess. This methane technology could prove very useful then. Of course it also shows how a larger, smarter grid will have great value, averaging those transients over wider areas.

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