The Audi e-gas plant in the city of Werlte in Lower Saxony (earlier post) produces CO2 neutral-fuel (synthetic methane from water, renewable electricity and CO2); it now also contributes toward stabilizing the public power grid. After successfully completing a test sequence, the plant is now qualified for participating in the electricity balancing market.
In the German electrical energy mix, the share of renewable energies is growing rapidly, reaching 33% in the first half of 2015. However, regional expansion of wind and photovoltaic generation plants leads to increasingly larger load fluctuations. It is therefore important to have flexibly available consumers such as the Audi e-gas plant to buffer load peaks and thereby stabilize energy grids.
The Audi e‑gas plant in Werlte (Emsland) is able to respond to even slight load changes in the electricity grid to balance them out. This has resulted in the plant being accepted under the direction of grid operator Tennet TSO GmbH. The plant had to be able to draw 6 MW of power from the grid within five minutes as well as run prescribed load profiles.
By passing this test, the Audi e‑gas plant has been qualified for participation in the electricity balancing market that is organized by the grid operator. As a result, the plant can now target higher annual operating times, which benefits the power grid and the amount of Audi e‑gas that is produced.
The power-to-gas (PtG) plant in Werlte, which produces synthetic methane (Audi e‑gas) from water and CO2 utilizing wind-generated electricity, was launched in 2013 adjacent to an existing biomethane plant operated by power company EWE in the Emsland region of northern Germany.
One of the ideas behind the plant and its location was to obtain the CO2 required for methanation from the biogas plant. When the Audi e-gas plant runs, it supplies the hygienization and amine scrubbing systems in the biogas plant with heat. This therefore considerably increases the overall efficiency of the Power-to-Gas/biogas plant.
This approach appears promising because while the PtG plant has a variety of heat sources (electrolyzer, methanation unit) the biomethane plant has a number of heat sinks (hygienization of waste, fermenter heating, CO2 separation). This does pose some special challenges because the PtG plant only runs intermittently whereas the biomethane plant has a continuous heat demand. The increased operating time resulting from participating in the balancing market should have a positive effect.
Audi customers can pay with the Audi e‑gas card at CNG fueling stations, and Audi then feeds equivalent quantities of e-gas into the German natural gas network.
The Audi A3 Sportback g‑tron with 81 kW (110 hp) of power is currently available from dealers. The new Audi A4 Avant g‑tron with 125 kW (170 hp) will follow next year.
Both models can be driven climate-neutrally with Audi e‑gas—i.e., the amount of CO2 that is emitted during vehicle operation is equal to the amount that is chemically bound to produce the fuel.
In addition to e‑gas production in multiple plants, Audi also working on a broad front to develop other CO2‑neutral fuels: Audi e‑fuels. In early 2015, a pilot plant in Dresden that is operated by project partner sunfire GmbH started up production of the synthetic fuel Audi e‑diesel. Audi is also conducting joint research on the synthetic manufacture of Audi e‑gasoline with the French company Global Bioenergies S.A. (Earlier post.)
In another project, Audi is working together with the USA-based company Joule Unlimited Technologies, Inc., which is using microorganisms to produce the synthetic fuels Audi e‑diesel and Audi e‑ethanol. In the field of e-gas, Audi is also working with a partner to develop a new production method in which the methanation process runs on biological pathways.