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Audi unveils e-gas project: synthetic methane from the methanation of green hydrogen; series production of CNG models in 2013 powered by e-gas

Audi A3 TCNG for e-gas project. Click to enlarge.

Starting in 2013, Audi will begin series production of TCNG models whose engines—derived from TFSI units—will be powered by e-gas: synthetic methane produced via the methanation of hydrogen produced by electrolysis using renewable electricity. Audi’s newly unveiled e-gas project is a component of achieving its goal of “Audi balanced mobility”—i.e., achieving a neutral CO2 balance across the entire mobility chain.

Audi says that the e-gas project, which after three years of research is now entering the practical phase, is a cornerstone of its mission to set up an entire portfolio of sustainable sources of energy. Audi will supply three sources of green energy in the scope of the e-gas project: electricity, hydrogen and methane gas. Respectively, each one is suitable for a very different type of drive concept: for electric cars, fuel-cell vehicles and CNG vehicles. The e-gas project consists of two main components:

  • Audi is contributing to the construction of offshore North Sea wind turbines which will generate clean power,that is then fed into the public power grid. Audi wants to use green power to produce and also operate its electric-drive e-tron models in the future.

  • A new plant, the e-gas project’s second component, will use the remaining green power to produce hydrogen by means of electrolysis. This source of energy, generated in a climate-friendly manner, can be used to power fuel-cell vehicles in the medium-term. Audi will also combine hydrogen with CO2 in an additional methanation step to produce methane. Although this methane is also known as synthetic natural gas, the company refers to it as Audi e-gas.

    Audi notes that methanation is particularly advantageous in that the reaction occurs with the aid of CO2, which consequently is not discharged into the atmosphere. This results in a completely closed CO2 cycle.

Audi says that its e-gas project provides an answer to the question as to how green power can be efficiently stored, irrespective of location. If there are strong sea winds, for instance, then surplus power supplies can be converted to e-gas and stored in the largest available energy-storage system: the public gas network. If necessary, this energy can flow from the gas network back to the power grid at any time.

Along with our project partners, AUDI AG is realizing a method which puts CO2-neutral mobility within reach. Our technology has the potential to give new direction to the discussion on expanding renewable sources of energy. We ourselves are taking the initiative and are complementing electric mobility with an equally eco-friendly concept for long distances.

—Michael Dick, Member of the Board of Management for Technical Development

Audi has completed the research phase of the e-gas project and will take the second step in mid-2011: investing several tens of millions of euros in the construction of an industrial facility. Audi will kick off this large-scale energy project together with its project partners: SolarFuel GmbH from Stuttgart; the Centre for Solar Energy and Hydrogen Research (ZSW), also based in Stuttgart; the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES) in Kassel, Germany; and EWE Energie AG.

Wind turbines are the first significant component of the Audi e-gas project. During the project’s first phase, four large power plants at an offshore wind park in the North Sea are being financed by Audi and a regional power-supply company. Rated at 3.6 MW each, these four turbines are to supply some 53 GWh of electricity annually.

Concerning the use of wind power in Germany, offshore wind-power stations currently play a minor role. Located far from the coastline, they harness wind averaging 30 km/h (19 mph) to produce about 40% more energy than onshore stations.

The project’s second large component is the e-gas plant, which will produce hydrogen and methane on an industrial scale. Ground is scheduled to be broken in Werlte, Germany in July 2011. The e-gas plant is connected to a waste-biogas plant, which supplies the concentrated CO2 necessary for methanation and which would otherwise pollute the atmosphere. The plant will annually produce some 1,000 metric tons of e-gas while consuming 2,800 metric tons of CO2.

The e-gas plant has two main components: an electrolyzer and a methanation unit. There is also piping technology, tanks, open-loop and closed-loop control electronics, and compressors for feeding e-gas into the natural-gas network. In January 2011, a lab facility with an output of 25 kW was set up for testing purposes.

The electrolyzer runs on green electricity. Aided by polymer electrolyte membranes, the electrolyzer splits water into its components: hydrogen (H2) and oxygen (O2). Hydrogen will not be used directly for fuel cell vehicles during the project’s first phase; instead, after being separated and dried, it is placed into a storage tank and then the methanation unit.

Here, the hydrogen is combined with carbon dioxide (CO2) to create methane (CH4) as per the Sabatier reaction; water (H2O) forms as a by-product.

Even during this initial phase of the e-gas project, the electricity generated by wind power and the methane produced at the plant will suffice for 2,500 motor vehicles in total. Some of the wind-generated electricity would be enough to manufacture 1,000 units of the A1 e-tron and propel them 10,000 km (6,200 miles) per year. An additional share will be fed into the grid; surpluses within the power grid would thus benefit the e-gas plant, too, Audi says.

By means of the e-gas generated via renewable energy, 1,500 units of the A3 TCNG could each be driven 15,000 km (9,300 miles) annually, with 150 metric tons of e-gas remaining for the public gas network. As needed, this gas could also flow back. All in all, that represents a big boost to the power grid and equates to far more than 30,000,000 climate-neutral kilometers (18,700,000 miles) driven every year.

In terms of the well-to-wheel analysis, a compact natural-gas car powered by e-gas emits fewer than 30 grams of CO2 per kilometer (48.28 g/mile), including all emissions created during construction of the wind turbines and the e-gas plant. Only electric vehicles which are directly supplied with wind-generated electricity perform even better: they emit under 4 g/km (6.44 g/mile). However, Audi notes a drawback in the overall energy picture regarding vehicle production: a lot of energy is needed to manufacture the batteries.

Audi says that its e-gas project is capable of solving several pressing problems faced by the sustainable energy-supply industry all at once. In the process chain, clean power, hydrogen and methane are produced: three key sources of energy for future mobility. In the medium-term, this technology has the potential to establish a highly flexible power-supply infrastructure for electricity, heating and motor vehicles which is based entirely on renewable energies; in addition, the respective percentages of the three sources of energy can be adjusted as required.

Renewable energies already account for 17% of electricity generated in Germany; renewable sources of energy are forecast to make up 77% of Germany’s overall electricity consumption by the year 2050.

The Fraunhofer Institute for Wind Energy and Energy System Technology (IWES) was commissioned to conduct a study by WindEnergie, a German association. According to the study, wind power could be harnessed to realistically generate some 390 terawatt hours (TWh) of energy; this would have satisfied 64.7 percent of Germany’s overall electricity consumption in 2010 (603 TWh). Overall output in the computational model amounts to 198 gigawatts (GW).

The production of electricity via wind and sun, however, is subject to natural fluctuations and the necessary storage capacity is currently very low. Pumped-storage power plants are capable only of short-term storage: during an emergency in Germany, they could supply power for all of an hour. All other solutions, such as compressed-air energy storage plants, are similarly very limited regarding capacity and period of storage.

Audi argues methanation of hydrogen using renewable energy helps solve this problem: the power grid is linked to the underground gas network, which can store surplus power supplies for months. The gas network has a potential capacity of 217 TWh, in contrast to the power grid’s storage capacity of just 0.04 TWh. The latter’s transport capacity, moreover, is just one tenth of that of the gas network.

Energy can be conveyed from the gas network—perhaps by means of gas-fired power plants or, in a decentralized manner, in block-type thermal power stations—back to the power grid at any time. New, decentralized cogeneration power plants can boost efficiency even more. In addition, methane is also suitable for the supplying of gas to private residences or providing high-temperature process heat.

The efficiency ratio of the e-gas pilot plant—from wind turbine to methane gas—is about 54%. If the dissipated heat is also used, this value is considerably higher still. The aim is to achieve an efficiency ratio above 60% in the future. Audi says that the potential to store large quantities of energy—made possible by pairing electricity with gas on the one hand as well as wind energy and solar energy on the other—can “truly invigorate” the expansion of renewable sources of energy. The Audi e-gas project can easily be replicated in any country with an existing natural-gas network.

The Audi A3 TCNG. The Audi A3 TCNG can run on the e-gas which Audi produces in the methanation unit. Via the “balanced cycle method”—similar to the purchasing of green power—A3 TCNG owners should be able to fuel their vehicles with wind energy starting in 2013. When a driver refuels with e-gas, the corresponding amount of renewable energy required to produce this e-gas is fed into the grid.

The high octane rating of approx. 130 RON for natural gas, biomethane and also for e-gas facilitates a high compression ratio in the turbo engine, which ensures high efficiency. The Audi A3 TCNG also boasts a bivalent configuration: if the natural-gas tanks run empty and there is no CNG station nearby, the vehicle can run on conventional gasoline with no drop in performance.



Nothing else can compete with the cost / efficiency & CO2 of off peak charing of EV's using wind & nukes.

It makes no sense to turn high value electricity (~5c/kWh) into low value natural gas (~2c/kWh)

If you did have 'excess' electricity it would make more sense to use a heat pump to heat water and displace natural gas


This is an odd announcement, it tries to show that wind could power cars in one of the most inefficient manners possible.


Oh come on Wintermane. I tell you that this project is inefficient and nonsensical because it takes 200 Billion EV miles driven and turns it into 18.6 million miles driven in, and your response is:
"Dave your just not gona understand and frankly I dont care."

Really? Why don't you just call me a poopy-head and be done with it :-)

Either show me where I'm wrong with some facts and logic or admit you're wrong.


This one is hard to defend on the merits. It is more of an exercise to show what can be done rather than what should be done.


Ok we have seen alot of plans to make h2 out of excess capacity.. alot of future coal plants will use this in so called clean coal powerplants...

This part is proven and simple enough. It works so long as you have a large supply of excess power you cant sell for more then you can sell the h2...

This just goes one step farther by also combining a methane plant into the mix so if you also dont need more h2 you can over time convert your extra h2 into methane to sell.

It works off the fact alot of the time they cant actualy sell thier power for much and a fair amount of the time they cant sell it at all.

BUT it only works if the methane is valuebale enough to be worth more then just doing notbing and venting the excess h2...

I assume they did the beancounting and know.


Folks, the windmills keep spinning if its windy, even if there is no demand for electricity at midnight, so instead of wasting the power use it to make methane.. its not that complicated. You cant use the excess power to charge non-existent BEVs, yet. Think of it as an inefficient battery, but perhaps cheaper overall.


There is demand at midnight, just not as much as a summer week day. The other plants throttle back to allow the wind turbines to produce.


Not enough demand.


People in cold climates are using off peak electricity to heat thermal masses for warming their houses during the day.

There is demand, your refrigerator, clocks and many other devices still run. There are street lights and stop lights still running. Many commercial and office building still require electricity at midnight.

11 pm to 7 am use might be only 30% of peak use that day, but the profile is known and generation can be planned. It is done every day in California and can be elsewhere as well.


I wouldn't write this off as a complete nonsense.

Methanating energy is not a new idea, only its known processes are not very efficient yet, so it is expensive.

In this process, almost everything depends on the price of the electricity they use for electrolysis. If they can get electricity dirt-cheap (excess wind can be bough for NEGATIVE payments at some places, see the recent CleanTechnica article), this may even prove financially viable, especially if the German government supports it. And why wouldn't it? If it really provides a way for a 60% CO2 emission reduction compared to the Prius (~100g/km), then why not?

By the way, recently, a lot of articles have reported breakthroughs about producing H2 from solar energy using cheap catalysts. This may replace the hydrolysis process element in the medium term and make methanation MUCH MORE efficient/cheap.

About storage: Here in Hungary energy companies have built HUGE storage facilities (enough for 6 months for the whole country) in response to the two recent Ukrainian-Russan CNG dispute (CNG import lines were cut off for months). We can store extreme amounts of CNG so a system like this may be absolutely feasible if other parts of the process are financially viable. (Also there are quite a lot of CNG vehicles on Hungarian roads because it is still much cheaper than gas/diesel).

Gas is $8,15/us gallon here. Diesel is almost the same.


This may be an important consideration:

If methanation is used in conjunction to wind farms (instead of the wind farms producing for the electric grid) then wind capacity factor may soar up and simultaneously reduce its production price. Methanation may be done at the wind-farm so electric grid connection is not necessary at all (an important factor for project siting, currently).

If CO2 production from the atmosphere could be made cost effective, CNG use would explode.


Like I said, would you rather have an $8 therm of synthetic methane or a 40 cent therm of natural gas? If I were heating my home or fueling my car, I will take the natural gas for obvious reasons.




Hmm Robert Zubrin should be proud. Mars on Earth.
Storing excess energy in pumped reservuars makes more sense. It's cheap, turnaround efficiency is high, technology is very mature.


"SJC says:
Like I said, would you rather have an $8 therm of synthetic methane or a 40 cent therm of natural gas? If I were heating my home or fueling my car, I will take the natural gas for obvious reasons."

You cant look at it like its $8 a therm since its made with electricity that has NEGATIVE value at certain times of low demand.. the high cost of energy storage and the high variability of wind power makes it a very expensive way to generate electricity. Dont forget, you cant idle baseload plants easily. Wind needs low cost storage.. be it pumped hydro, batteries, bauxite refining, thermal storage or compressed air storage, whatever is cheapest.


I would say a few wind turbines should find a place on the European grid. It is not like they do not pay enough for electricity in Germany and they have NO demand at night.

Pumped hydro and CAES are viable ways to store energy to recover during the day. Making synthetic methane when natural gas is cheap makes no sense.



You've nailed it: Whatever is cheapest.

This just seems to be a very unrealistic exercise compared to other means and most likely some green washing.

Pumped hydro can be between 70-85% efficient so it is hard to imagine the scenario where this could possibly make sense.

You would have to NOT have easy access to any of the other tested and more efficient processes and you would have to have an available supply of H2 and C02 at the site along with somewhere to put the resulting methane.

I'm not even CLOSE to an expert on this type of grid storage and have not even bothered reading up on different methods to be an arm Monday morning quarterback to second guess everyone's decisions in this area.
But this one seems to fail the common sense test big time and looks like the type of green washing that gives us a bad name. I hope they don't end up using gov't money for something like this if it's just green washing.


Use the nighttime electricity for heat pumps, it is not like it does not get cold in Europe during the winters. While you are at it make them ground source heat pumps for more efficiency, tell the Russians to keep their natural gas.


"Use the nighttime electricity for heat pumps"

Totally agree. For large building air conditioning too (large cold thermal mass in the basement during the summer, hot in the winter. Such things could buffer several days worth of wind power volatility at cheap rates).

"tell the Russians to keep their natural gas"

Excellent idea!


Peak shaving by those methods makes sense. It is hardware intensive, but if you pay enough for daytime electricity it can pay off.


I think the real motivation is that high level management at Audi realizes, and other realize, is we have to slash our carbon emissions. Basically, in the long run, coal, oil, natural gas have to become worthless. We have to become carbon neutral.


One of the latest themes is make oil like salt. At one time salt was indispensable, then refrigeration came along and salt was useful.


This is THE SOLUTION to fuel problems and pollution and costs for all the time to come. Nobody in this incompetant website approve audi for the simple reason that they need stupid problems like gasoline cars with pollution and high fuel cost to have something to chat about, if audi resolve the problem then the problem for incompetants is finding some subject to expose their poor science knowledge.

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