In Emsland in Lower-Saxony, Audi operates the world’s first industrial facility that produces artificial natural gas from biogas, green electricity and water. With this fuel, natural gas vehicles can drive with almost no CO2 emissions. And work is continuing on other renewable fuels for conventional engines.
Climate-neutral fuel from biomass and renewable energy that is sustainable and offers high performance and range – this sounds like paradise. Yet Audi, together with its partners, has shown that it is possible: the “e-gas” project uses power-to-gas technology, which allows large-scale electricity storage using the natural gas network for the first time.
The pilot plant in Emsland uses carbon dioxide from a waste-processing biogas plant for the gas. Green electricity is used to split water into oxygen and hydrogen. Methane is produced from the hydrogen and CO2, resulting in e-gas. “It is chemically and physically identical to normal natural gas,” says Tobias Block, one of the developers at Audi.
Green natural gas technology with great potential
This is an innovation with real benefits. First, e-gas is nearly carbon-neutral – the amount of CO2 released when driving with this fuel was bound during fuel production. All conversion losses included, CO2 emissions are 80 percent lower compared with fossil fuel. Second, the system stabilizes the electricity grid and utilizes excess green electricity, such as that produced during high winds. Thus, energy that would otherwise be unused is converted and stored in the natural gas grid. Third, Germany already has more than 100,000 natural-gas vehicles and over 900 NG filling stations where drivers can refuel with e-gas.
Audi currently provides e-gas for its A3 Sportback g-tron natural-gas vehicle, which was successfully introduced to market in 2014. If a customer refuels with a special “e-gas card” in Germany, the same amount of e-gas is fed into the grid.f
The project is not profitable yet. “But if we wait until every customer buys an electric or hydrogen-powered vehicle as their next car or the car after that, the energy revolution in the transportation sector will take too long to reach climate-based objectives,” says developer Block. “We need solutions that are already feasible today, with existing technology and infrastructure.”
Many countries have made further progress: Italy has about ten times as many natural gas vehicles as does Germany. And in Switzerland, the parliament is working to include CO2-neutral fuels such as e-gas in emissions calculations. Another challenge: the electricity in an e-gas plant is subject to the same taxes and expenses as residential electricity. “This is so despite the fact that we convert excess energy into a renewable fuel – there is a lack of economic incentive for chemical energy storage” states Block.
Other renewable fuels are being researched
The mobility of tomorrow will require a mix of different technologies. Audi wants to supply all its “tron” drives (electric, natural gas, fuel cell) with green energy in the future. Since 2012, Audi has been working together with an American start-up that converts brackish water to synthetic diesel by using microorganisms and sunlight. In a plant in Dresden, the company has already generated synthetic diesel based on CO2. “We filled the Minister of Research’s Audi A8 with this e-diesel,” says Tobias Block. Liquid synthetic fuels could also quickly assume a greater role, the developer says. An adjustment in government policy would be necessary to make the use of alternative fuels more widespread.
Audi sees itself as a leader in these green fuels and continues to search for start-ups, other technology companies, and energy suppliers around the world for partnerships in this field. The goal of the e-fuels strategy: 80% fewer CO2 emissions in traffic – with fuels for engines that have already been built and transported through pipes that have already been laid.
Currently, the number of power-to-gas projects in Germany is increasing – which is also due to the ambitious projects of the automotive industry. Audi intends to start providing its e-gas to two new “g-tron” models in the near future, the A4 Avant and A5 Sportback – and eventually in all European countries. The project will further the energy revolution and show that electricity from renewable energy sources can be stored and transported as “green” gas.