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Audi opens power-to-gas facility in Werlte/Emsland; e-gas from water, green electricity and CO2

Audi’s e-gas plant. Click to enlarge.

Audi has opened its e-gas plant in Werlte, making it the first automobile manufacturer to develop a chain of sustainable energy carriers. (Earlier post.)

The Audi e-gas plant, which can convert 6MW of input power, utilizes renewable electricity for electrolysis to produce oxygen and hydrogen. Because there is not yet a widespread hydrogen infrastructure, the hydrogen is reacted with CO2 in a methanation unit to generate renewable synthetic methane, or Audi e-gas. The e-gas is virtually identical to fossil natural gas and will be distributed via an existing infrastructure—the German natural gas network—to the CNG filling stations beginning in Germany in fall 2013.

Components of the e-gas plant. Click to enlarge.

The Audi e-gas plant will produce about 1,000 metric tons of e-gas per year, chemically binding some 2,800 metric tons of CO2. This roughly corresponds to the amount that a forest of more than 220,000 beech trees absorbs in one year. Water and oxygen are the only by-products.

Audi built the e-gas plant in collaboration with the plant construction specialist ETOGAS GmbH (formerly SolarFuel) (earlier post) and its project partner MT-BioMethan GmbH on a 4,100 m2 (44,132 sq ft) plot of land owned by EWE AG. Ground was broken in September 2012, and the topping-out ceremony was celebrated in December.

The efficient use of energy flows is the top priority in the production sequence of the plant. The waste heat given off during methanation is used as process energy in the adjacent biogas plant, significantly increasing overall efficiency. In return, this plant supplies the highly concentrated CO2 required as a basic building block for the e-gas. This CO2 thus serves as a raw material and is not emitted to the atmosphere.

It is anticipated that the e-gas from Werlte will power 1,500 new Audi A3 Sportback g-tron vehicles for 15,000 kilometers (9,321 miles) of CO2-neutral driving every year. The 1.4 TFSI in the five-door model can burn natural gas, biomethane and Audi e-gas; with its bivalent design it can also use gasoline. This gives it a total range of some 1,300 kilometers (808 miles).

Customers can order a quota of e-gas when they purchase the car. This enables them to take part in an accounting process that ensures that the amount of gas that they put in their vehicle at the natural gas filling station is supplied to the grid by the Audi e-gas plant. Payment and billing is handled via the Audi e-gas refueling card.

The Audi A3 Sportback g-tron, which is scheduled for launch late this year, consumes on average less than 3.5 kg (7.72 lb) e-gas per 100 kilometers (62.14 miles). CO2 tailpipe emissions are less than 95 grams per km (153 g/mile) in the NEDC. Driving with Audi e-gas is climate-neutral, since the CO2 generated when the vehicle is driven had been bound previously during the production of the e-gas.

Even in a comprehensive wheel-to-well analysis that includes the construction and operation of the e-gas plant and the wind turbines, CO2 emissions are just 20 grams per kilometer (32 g/mile). The groundbreaking environmental footprint was recently certified by TÜV Nord.

Audi notes that its e-gas project transcends the needs of the automobile industry and shows how large amounts of green electricity can be stored efficiently and independently of location by transforming it into methane gas and storing it in the natural gas network.

The e-gas project is part of Audi’s comprehensive e-fuels strategy. In parallel with the e-gas plant in Werlte, Audi also operates a research facility in Hobbs, New Mexico, USA, for the production of e-ethanol and e-diesel in collaboration with Joule. At this facility, microorganisms use water (brackish, salt or wastewater) sunlight and carbon dioxide to produce high-purity fuels. The strategic goal of these projects is to use CO2 as a raw material for fuels and thus improve the overall footprint substantially. The e-fuels strategy is an important pillar of Audi’s sustainability initiative.



Current coal fired power plants could recycle the CO2 emitted by their plants + some of the electricity produced, using this process.

CO2 could be stored temporarily and recycled during off peak e-energy demands?

The methane produced could be used to produce extra e-energy to meet peak demands?

Of course, this green process would be too clean, cost a bit more and would quickly be rejected by current 'Moneycracies' supporters?


Customers can order a quota of e-gas when they purchase the car. This enables them to take part in an accounting process that ensures that the amount of gas that they put in their vehicle at the natural gas filling station is supplied to the grid by the Audi e-gas plant.

This is the same idea that Bullfrog Power uses. An amount of green electricity and/or biogas is put into the distribution network to offset what you use elsewhere;


In early 2012, Bullfrog partnered with Chevrolet Canada to launch the Chevrolet Volt Bullfrog Power Edition, Canada's first EV to come with emissions-free, renewable electricity.


Would be nice to know about the efficiency of the process and the price of the natural gas they produce.

If the fuel price is competitive with fossil methane prices this should be a very-very good development since a lot of homes may switch to renewable methane.


I am wondering if it is possible to design a custom wind plant around a facility like this. Potentially, the costs may be significantly lower since the plant doesn't have to produce for the grid.

Tom A.

I had never heard of this. This is excellent! Ultimately, combustion is still involved (with the car burning the methane), but it's a huge improvement over petroleum industry. A brilliant and efficient system with a negligible carbon footprint. This sort of thing needs to be pushed here in the US. It's a great way to store renewable energy, where the plant can generate methane whenever the sun is shining and/or the wind is blowing (however the plant is powered). If it is powered by geothermal energy, it can generate methane 24/7 on a very even and predictable basis.


Coal plant exhaust is among the worst source of CO2 for this kind of system, because the high levels of sulfur and other contaminants in the coal-sourced CO2 stream poison the catalysts used for the hydrogenation reaction. Biogas can also have this problem, but most references indicate that coal has about four times more sulfur than biogas.

In addition, with biogas, you're looking at a CO2 source that is linked to the atmosphere via recent photosynthesis, unlike coal which comes from ancient fossil deposits - hence using biogas emissions results in no increase in atmospheric CO2, at any stage.

I can't seem to find the specific chemistry being used here, though - does the CO2 get converted to CO before being reacted with H2?

Kit P

“Would be nice to know about the efficiency of the process ...”

The thermal efficiencies are about 50%. Taking electricity and making methane is going backwards.

“I had never heard of this. ”

It has been on GCC before. The 'earlier post' would be your first clue.


"Taking electricity and making methane is going backwards."

Well, if you're talking about using a natural gas plant to make electricity which is used to make methane, yes.

However, as Germany abandons coal and nuclear in favor of renewables, their problem is how to store intermittent flows of electricity from wind and sunlight for later use - and this way, they can use that energy to create a hydrocarbon fuel for which the infrastructure (storage, power plants and pipelines) already exists. That's not going backwards, is it?


If you had a lot of EVs charging at night you might not need this.


This is about as dumb a greenwash idea as I have seen. You take renewable electricity and turn it into methane at some efficiency (~50% maybe). Meanwhile to generate electricity for other purposes, you burn coal and Germany is going to burn more coal as they shut down their nuclear facilities. Meanwhile Audi generates favorable publicity among the ignorant. It would be one thing to use renewable electricity to charge batteries for a plug-in vehicle as you would not be taking an efficiency hit on every step. With the Audi scheme you take a 50% hit generating the gas and then another 70+% hit turning the gas into mechanical power for an overall efficiency of 15% if you are lucky.



Predrag Raos

A nonsense not only from thermodynamic point of view, but from the technological one too. Even if existing pipelines could not handle pure hydrogen, addition of several percent of H2 into NG would not substantially change parameters of the gas. The only thing that makes full sense is coal to liquids (or DME) by use of a nuclear generated hydrogen. Impressive work was already done in this direction exactly in Germany, but then came the green Talibans...


VW is absolutely crazy against automobile electrification. This absolutely demonstrating that. Instead of using wind power for EV with at least 70% efficiency Audi is using expensive and complicated proces and finally getting wind power to wheels efficiency no more than 15% (average would be 10%).

Kit P

“as Germany abandons coal and nuclear in favor of renewables ”

I am an old guy. I have heard all this nonsense before. There is a certain amount of energy that we can get from renewable energy but an industrial society needs coal and nuclear to power it. NG works too if you have it.

Wind and solar is a very dumb way to produce energy except as a hobby. The greens in Germany will never learn this but the people responsible for keeping the lights on will make sure they meet the needs of customers while internet sites will meet the needs of those who need a fantasy.


The only relevant "efficiency" when talking about wind-energy is economic efficiency, not thermodynamic efficiency. The reason why we dont have 500% of our electricity renewable is not because there is not enough wind, but because there is not enough money for wind turbines.

THEREFORE : if renewable methane in a combustion engine is in 2013 cheaper per km drive than electric driving, it is more efficient ! It doesn't matter if it is 15% or 95% thermal efficiency.

And from an economic point of view, it is very hard to calculate the "cost" of the electricity, because they will use excess electricity when there is overproduction of wind energy. This overproduction will increase dramatically in the near future as ever more huge wind turbines are coming online (the big projects in the north sea are only starting), so we will probably have ever more abundant "free" electricity, since there is no one else to use it when the wind blows at night. Of course, it would be even better if there are millions of BEV charging at that moment, but the rise of excessive free wind power is steeper than the rise of BEV's. Whenever the number of BEV's becomes so high that they buy the electricity for a better price, the hydrogen plants will slow down. As long as no one uses the cheap electricity, I'd rather have it transformed to H2 or CH4 than seeing the turbines shut down.


soltesza, One would either have to partially grid connect or modularize the process with only so many cells coming on line as power becomes available. It is not just the intermittancy but also the level of supply that varies with wind and solar. However, if the storage process equipment is low cost enough, one could essentially catch 100% of all energy produced by the solar or wind, Of course, lesson by the process inefrficiency, but then too, you would have a value added fuel worth more than electricity.


I wish GCC had a comment rating. I'd give a Thumbs Up to HarveyD every time. Thumbs up Harvey.


@ Kit P:
"I am an old guy. I have heard all this nonsense before."
"Wind and solar is a very dumb way to produce energy except as a hobby."
I'm over seventy, so I can count myself to the older generation, too.
I assume your negative point of view focuses mainly on the aspects of economics. If that is so, perhaps you can give me an answer to the following questions.
All the sewage pipes terminating at a sewage plant and the sewage plant itself are not exactly cheap. Isn't the plumbing including the toilet bowl etc. just pure superfluous luxury? Wouldn't it be more economical to just open your front door and leave your excrements on the street? That's the way they did it in medieval times. Of course they had to suffer the consequences.
Nevertheless, it was more economical.

Kit P

“The only relevant "efficiency"…”

Nonsense, here is why. For example, say we can produce power at $50/MWh using $4MMBTU NG. With a good wind resource we can produce power at $40/MWh and therefore build lots of wind farms. The $4MMBTU NG not used for making power can be used for transportation or heating homes in winter.

Then we build more wind farms than we need. If the wind farm can make $4MMBTU NG, great but that poor thermal efficiency means that the NG cost $10 MMBTU to produce.

“so we will probably have ever more abundant "free" electricity …”

When Alain is willing to work the night shift for ‘free’ then maybe he will understand that the money to pay workers to make power is not free.

Even if Alain is willing to work ‘free’ I am not. I like my cheap electricity made with coal. Germany can do whatever they want. If Alain, Brotherkenny4, and Harvey want to come to my backyard to produce power cheaper with less environmental impact than my utility, then I will be happy to buy it from them. Of course, I will want to see the EIS that show that the impact of wind and solar is not huge.


Guys guys guys, did you all miss this salient point: "The waste heat given off during methanation is used as process energy in the adjacent biogas plant, significantly increasing overall efficiency. In return, this plant supplies the highly concentrated CO2 required as a basic building block for the e-gas."

Audi's E-gas plant is an "add-on." They are already generating methane (from the biogas plant) and electricity (from wind). All they're doing is closing the loose ends (the turbines produce too much electricity and the biogas plant produces waste CO2) and increasing the amount of non-fossil methane they can put into the "natural" gas network.


It seems that most of those who critiqued the energy efficiency did so whilst ignoring the CHP technology used.

Economic efficiency may be a different matter, but the energy efficiency should be pretty good.


Good catch, I was wondering about that too.

It is worth to know that there is a huge number of biomethane plants already deployed in Germany (typically smaller sizes at farms). If this can make them more efficient with leftover renewable energy, at a small-enough price, this could be something worthwile.

The 20g/km CO2 figure is nice but we would need to know about the price of the bio-methane they are selling.


Kit P,

We seem to agree passionately that only the $ are relevant, not the thermal efficiency.

I never said the NG will be free, I only say the electricity often is (almost) free, because the production is higher than demand.

Of course, the ultimate cost of the synthetic CH4 is not only determined by the price of the electricity, but the discussion whether it is sound to produce synthetic H2 or CH4 should ultimately be based on $. And that evidently includes wages.
It is not because H2 is produced at night, that all the workers have to be there at night. Those elektrochemical facilities work almost "automatically" and just as in any powerplant or chemical facility, while there are constantly people at the facility, the necessary maintenance can be mostly performed at "normal working hours".

In general, the workers in the chemical industry are very well paid, so nobody has to work for free.

We even have to include another fact, and that is that Germany imports most of its fossil fuels, so even if the price is somewhat higher for wind energy than for fossil energy, macro-economically it is ultimately cheaper for the Germans to produce wind-energy than coal-energy, since the extra cost for wind-energy is more than compensated by the the fact that the money remains in the local economy, instead of disappearing to a foreign fuel supplier.

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