The world’s first industrial plant for generating synthetic methane (e-gas) from CO2 and renewable electricity is under construction in Werlte, Germany. It will produce gas that can be fed into the natural-gas network. “This power-to-gas technology opens up new possibilities for sustainable mobility and tomorrow’s energy industry. The e-gas project marks a transition toward alternative forms of energy for automobiles,” explains Reiner Mangold, Head of Sustainable Product Development at AUDI AG.
The Audi e-gas plant, which can convert six megawatts of input power, will utilize renewable electricity for electrolysis. This process splits water molecules into oxygen and hydrogen, or Audi e-hydrogen, which could one day power fuel-cell vehicles. Because there is not yet a widespread hydrogen infrastructure, however, the hydrogen is then reacted with CO2 in a methanation unit to generate renewable synthetic methane, or Audi e-gas. Chemically speaking, this e-gas is nearly identical to fossil-based natural gas. As such, it can be distributed to CNG stations via the natural gas network and will power vehicles starting in 2013.
The CO2 used in Audi’s e-gas plant is a waste product from a nearby biogas plant, operated by energy provider EWE. The CO2, which would otherwise pollute the atmosphere, is chemically bonded into the fuel at the Audi e-gas plant – making Audi e-gas climate-neutral. The e-gas plant will annually produce about 1,000 metric tons (1,102 US tons) of e-gas and will chemically bind some 2,800 metric tons (3,086 US tons) of CO2. This corresponds to the amount of CO₂ that 224,000 beech trees absorb in a year.
Audi e-gas is an energy-rich fuel ideal for internal combustion engines. The Werlte facility will generate enough CO2-neutral e-gas to power 1,500 new Audi A3 Sportback TCNG vehicles 15,000 km (9,320 miles) every year. This compact five-door car will arrive at dealerships in late 2013. Audi plans to launch a second TCNG model, based on the A4, in 2015.
A special certification procedure will verify that the same amount of e-gas that owners purchase for their Audi TCNG vehicles is fed into the network by the e-gas plant. A similar balanced-cycle method is used to verify procurement of green power.
The German energy industry can benefit from Audi’s e-gas strategy, as it addresses the nagging challenge of how to store renewable electricity efficiently and irrespective of location. The ability to store large quantities of wind or solar energy via the dual electricity/gas principle could significantly foster the expansion of renewable energies. The Audi e-gas project can be easily replicated in any country with a natural-gas network.
The Audi e-gas plant in Werlte is being built on a site owned by energy provider EWE AG measuring 4,100 m2 (44,132 sq ft) overall. Ground was broken in September 2012. As owner, Audi is constructing the plant in cooperation with equipment manufacturer SolarFuel GmbH. They have prioritized the optimization of energy flows. Waste heat generated during electrolysis and methanation, for example, is used in the adjacent facility – thus tremendously enhancing overall efficiency.
Once the electrolysis units have been installed, the methanation reactor will be supplied and connected. This specialized unit some 16 meters (52 ft) in height will be provided by MAN, a sister company in the VW Group. e-gas production will begin in early 2013 and feeding into the public natural-gas network in summer 2013.
AUDI AG was honored in November 2012 for its e-gas project. The Working Group for Efficient and Environmentally Friendly Energy Use (German: ASUE) presented Audi with 15,000 euros and – in the Environmentally Friendly Mobility category – a Gas Industry for Innovation and Climate Protection award.