26.06.2013
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Power to gas – green methane

World's largest P2G facility ramps up

Yesterday, the world's largest power-to-gas (P2G) facility went into operation in Germany. With a capacity of six megawatts, it is designed to make "green methane" out of excess green power. Cars could then run on this fuel.

German automobile manufacturer Audi is behind the facility, which it plans to use to fill up 1,500 models of the new A3 g-tron with some three million cubic meters of methane; each car would then be able to drive 15,000 kilometers annually – or 22.5 million kilometers for the entire fleet.

The facility will then have to run for 4,000 to 4,500 full-load hours a year. "It always switches on when there is too much wind or solar power on the grid," explains Stephan Rieke, spokesperson of Etogas, a development partner of research center ZSW, which developed the system. The power to run the facility is purchased from the exchange whenever prices are very low because of excess wind and solar power.

 - Jochen Flasbarth (left), President of the German Environmental Agency, and Heinz Hollerweger, development head at Audi, take the first test drive.
Jochen Flasbarth (left), President of the German Environmental Agency, and Heinz Hollerweger, development head at Audi, take the first test drive.
AUDI AG

The new facility in Werlte is 24 times bigger than the second-biggest, which went into operation in October 2012 (also in Germany). Both are the product of development work done by ZSW and Etogas (formerly Solarfuel).

The basic idea is that excess wind and solar electricity is used to split water into its two components, hydrogen and oxygen, by means of electrolysis. This hydrogen then reacts with carbon dioxide to produce methane, which can be used not only to fuel cars, but also in basically any way natural gas can – for instance, for heating or to generate electricity again.

Greater efficiency from waste heat recovery

The new electrolyzer is 10 meters tall and installed in a hall with a floor space of 1,200 square meters – the size of a standard public pool. The methane conversion process takes place outdoors. To increase efficiency, waste heat is used as process heat in the nearby biogas facility. An automated control system that can be remotely controlled ramps the production process up and down.

For Etogas, the new six megawatt system marks the beginning of commercial applications. "Over the next 10 years, we will begin providing the market with systems up to 20 megawatts," says Etogas head Karl Maria Grünauer.

Commercial production will begin in mid-August in Werlte. Audi has not, however, revealed the most interesting detail: what the price of this methane will be. Yesterday, I wrote over at the Energy Transition blog that truly "green hydrogen" is not expected to be competitive for the next two decades and that Germany would start with electrolysis using Germany's current power mix – exactly what Audi is doing here. Once we know this price, we will know whether I was right or wrong – and this is one case where I would love to be proven incorrect. (Craig Morris with Denny Gille)

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