Blue crude: Audi pilot produces diesel fuel from CO2 and water

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A German pilot plant owned by car maker Audi has produced its first batch of e-diesel: a carbon neutral fuel made from carbon dioxide and water.

The new Audi Q7 E-Tron Quattro diesel-electric car is seen during the second press day ahead of the 85th International Motor Show in Geneva March 4, 2015. REUTERS/Arnd Wiegmann (SWITZERLAND - Tags: TRANSPORT BUSINESS) - RTR4S0W3
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A synthetic diesel pilot plant owned by Audi has produced its first batch of fuel made from water, carbon dioxide and green power, the German carmaker said.

Audi – which has been pursuing carbon-neutral fuels since 2009 – announced the breakthrough on its website last week, just four months after the Dresden research facility was commissioned, having been developed by local company Sunfire.

The German government-backed technology operates according to the power‑to‑liquid principle (see chart below) using water and CO2. The carbon is currently supplied by a biogas facility, although some is being extracted from the ambient air via direct air capturing, a technology of Audi’s Zurich‑based partner Climeworks.

Audi e-diesel
As the chart illustrates, water is heated to form steam, which is then broken down into hydrogen and oxygen by electrolysis. The hydrogen then reacts with the CO2 in synthesis reactors, again under pressure and at high temperature.

The reaction product is a liquid made from long‑chain hydrocarbon compounds, known as blue crude, which is then refined to yield the end e-diesel product.

The efficiency of the overall process – from renewable power to liquid hydrocarbon – is around 70 per cent, according to Audi, and the resulting fuel is free from sulfur and aromatic hydrocarbons, and is readily ignitable.

Audi says lab tests have found the e-diesel to be suitable for ad-mixing with fossil fuel derived diesel or for use as a fuel in its own right.

To demonstrate this, Germany’s federal minister of education and research, Johanna Wanka, made a show of putting the first five liters of the plant’s e-diesel product into her car – an Audi A8 3.0 TDI clean diesel quattro.

“This synthetic diesel, made using CO2, is a huge success for our sustainability research,” Professor Wanka said.

“If we can make widespread use of CO2 as a raw material, we will make a crucial contribution to climate protection and the efficient use of resources, and put the fundamentals of the “green economy” in place.”

Analysts note that the challenge for Audi, now, will be to ramp up production of the fuel to a commercial scale.

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  1. Ken Dyer 5 years ago

    It might keep a few ICE cars on the roads a bit longer, but it seems like a lot of mucking around when with an electric vehicle you just plug straight into the power source.

    • JonathanMaddox 5 years ago

      Think planes, heavy trucks, ships, and yes, farm equipment. But mainly planes. The US Navy has for decades discussed doing this *at sea* to produce jet fuel from nuclear energy and seawater.

  2. phred01 5 years ago

    what’s the cost /L

    • Miles Harding 5 years ago

      I would expect the answer to be “prohibitively expensive” 🙂

    • JonathanMaddox 5 years ago

      The product would sell for a price comparable to regular diesel, with a nice little “green” markup. It’s more that no full-scale industrial plant would be built to manufacture it unless the investors are confident that the oil price (and thus the price of their product) is going to be high enough for long enough to sustain the cost of capital.

      The developer, Sunfire, claim 70% efficiency of energy conversion from electricity to fuel. There’s around 10 kWh worth of energy in a litre of diesel (it varies), which is 70% of around 14.3 kWh, round it up to 15 kWh. 15 kWh costs about $1.35 retail, maybe as little as 45 cents wholesale off-peak. The energy costs are therefore entirely manageable.

      The capital costs of a full industrial-scale manufacturing plant, however, would be considerable — a recently built large gas-to-liquid synthesis plant in Qatar cost $24 billion, and that’s using very cheap “stranded” gas, not rather more costly renewable electricity, as the energy source.

      Electric fuel synthesis might have the advantage that it doesn’t necessarily require that enormous plant scale to produce a useful product, and the technical hitches might be able to be resolved over the course of development and even mass production of numerous smaller facilities. Or I could be wrong there.

      • Alastair Leith 5 years ago

        Even if it is 70% efficient in conversion to liquid fuel from electricity, what about the low efficiency of the ICE? I can see these synthesised liquid fuels being useful for aviation were energy density (by mass) is critical.

  3. Miles Harding 5 years ago

    That Audi (VW) headline should have read “We’re a bunch of dopes that can’t see past the petrol bowser”

    A game I play while filling the ICE car with dinosaur juice is to count up the kWh as the car fills. If it takes 60 Litres, I would get to about 560 kWh.

    That should be enough to drive the car about 800 km, so I could state this as (fuel energy) 70kWh/100km. Compare this to a Tesla Model S which will go about 500 km on around 80kwh total (not all of the battery capacity is usable), or 16 kWh/100km.

    Here we get to the same efficiency problem as the supposed hydrogen economy, except that it’s worse with at least 4 times the input energy needed by an all electric Tesla.

    This story is a perfect example of circular nonsense!
    The CO2 that is being converted to a hydrocarbon fuel came from burning those hydrocarbons in the first place.

    It’s a lot of effort to prop up an obsolete, inefficient fuel infrastructure.

    • Bararara Bororor 4 years ago

      You’re really narrow-minded.

      What happens after 500km with the Tesla? Can you just refuel in 5 minutes and drive another 500km?
      How about a truck? How much battery capacity does it need to go 500km? Can it refuel in 5 minutes?
      How about a jet engine? Can you replace that with batteries?

      About the benefits:

      1. it’s not reliant on existing fossil fuels.
      2. it’s reusing existing carbon in the atmosphere instead of pumping more of it from the ground. From a carbon footprint point of view, it’s no different from 100% electric

  4. Craig Allen 5 years ago

    We’re a long long way from having tractors and other high powered machinery being electric, so if this can eventually be produced at a competitive price it will be a means of reducing emissions in the mining and agriculture sectors. The other option would be converting agricultural waste to diesel.

    • wideEyedPupil 5 years ago

      There is very little ag waste to go around. City of Sydney wants to generate electricity for their dubious trigen precinct plan and had to claim everything within a 200km radius of the CBD. Leaves precious little for anyone else in Sydney, right?

    • JonathanMaddox 5 years ago

      Not true at all.

      Where overhead rail power supply is adequate, heavy rail haulage is electric, and where it is not, it is diesel-electric. Much modern heavy mining equipment is diesel-electric also, with some heavy trucks having the option of getting electric power from an overhead catenary.

      The very largest mining machines, indeed the largest land vehicles ever built, are electrically-powered coal excavators which literally drag a fat extension cord around behind them.

      Some heavy farm vehicles are also diesel-electric. Catenaries and extension cords aren’t likely to be cost-effective in agriculture, and batteries aren’t *yet* up to the task of powering the long weather-dependent duty cycles of ploughing and harvesting, but electric farm vehicles are not out of the question as a future development, either with improved battery technology or frequent swapping of batteries.

      • Alastair Leith 5 years ago

        love the dumper photo! Also buses in China are running using super capacitors storage and they charge at each passenger stop in a minute or something. Heard that from a Graphene researcher I interviewed for BZE radio.

        • Rikaishi Rikashi 4 years ago

          Apparently they use the supercaps for acceleration then switch to ICE. It cuts down on their emissions a lot.

    • JonathanMaddox 5 years ago

      As for converting “agricultural waste” to diesel, there was a very innovative business known as CHOREN (from Carbon, Hydrogen, Oxygen, RENewable) which worked successfully for a decade on fuel synthesis from gasified biomass. The biomass feedstocks proved both too expensive and too variable for the process to be viably scaled up at that time.

      The ghost of that company still exists, alas mainly as a technology provider to coal gasification and fuel synthesis projects in China. Coal, while filthy, is at least cheap and consistent!

      Obviously electric energy is also not presently a commercially viable source of energy for renewable fuel synthesis either, compared with fossil fuels, but in the long run it may actually be easier to source clean electricity in suitable quantity and quality than biomass.

  5. jim frank 5 years ago

    Why would you turn electrical energy into a fuel to power an ICE which has a 25% efficiency factor when the same electrical energy would power an electric motor with 90% efficiency factor?

    • Bararara Bororor 4 years ago

      Because the 90% efficient electric motor can’t run a car in the middle of nowhere, can’t store the energy for long periods of time, can’t run a truck for 1000 miles or a commercial airplane across the ocean.

  6. Radbug 5 years ago

    It’s not as good as Solar Methanol (It’s easy to turn H2 & CO2 into methanol) . Methanol has its own DMC (Direct Methanol Cell), it can recharge an EV at any service station, plus the CO2 can be reticulated & returned to sender. In Australia the CO2 can be piped back to the Nullarbor Giant Array, the pipes running alongside the Melbourne/Charters Towers double tracked railway, & the Sydney/Perth double tracked line, to receive the CO2 from Albury, Toowoomba, Dubbo, Adelaide etc., in addition to the DMC stacks powering the railway. The methanol tankers from Ceduna could backload recycled (yuck factor) water. Plus Lithium batteries are just getting better & better with every passing week.

  7. Nick Thiwerspoon 5 years ago

    You can manufacture “synthetic natural gas” in a similar way. The advantage is not cost, it’s that most advanced economies have a gas distribution and storage infrastructure which has 6 weeks plus of stored gas.

    Dunno how cost effective that would be though. Batteries are falling so rapidly in cost that it may be unnecessary.

  8. Andy Boothroyd 5 years ago

    As well as the waste of energy, presumably you have all the tailpipe emissions problems creating local pollution. It doesn’t mention what the emissions would be.

  9. Zac B 4 years ago

    this is a brilliant interim solution to address a global problem.. can’t take an addict off their addictive substance in one hit..need to ween them off 🙂

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