Carbon-Neutral Gasoline Out Of Air? Yes, There's A Caveat

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Call it last week's most unexpected headline: the idea that a group of engineers in Britain had managed to create gasoline ("petrol") out of ... thin air?

Indeed, it appears to be so--if you add energy (and sodium hydroxide).

Here's how it works: The process starts by blowing atmospheric air into a tower containing the sodium hydroxide, which binds to the carbon dioxide to form sodium carbonate.

Adding energy to that substance splits out the carbon dioxide specifically, which is then stored for later use.

Next, a dehumidifier removes water vapor from the air, and more energy is added to separate the hydrogen and oxygen molecules.

Mix the hydrogen with the carbon dioxide in the right proportions and you produce a synthetic gaseous hydrocarbon.

That, in turn, can be processed into methanol--which can be further turned into synthetic gasoline.

The resulting gasoline can either be used in vehicles directly or blended with conventionally extracted and refined gasoline.

The company that demonstrated the technology last week is Air Fuel Synthesis (AFS), based in the Northern town of Stockton-On-Tees.

Ironically, the town is less than 30 miles from the Sunderland plant where Nissan is about to start fabricating lithium-ion cells and assembling its Leaf electric car.

For countries whose policy it is to lower carbon emissions, the appeal of this kind of technology is that it can produce carbon-neutral gasoline.

That's because the process reuses atmospheric carbon dioxide, rather than burning new hydrocarbons and releasing more CO2 into the atmosphere.

AFS says it is now raising money to build the first plant that will produce carbon-neutral gasoline through air-fuel synthesis, at a cost of £6 million ($9.6 million).

"Demand for specialist high quality low-carbon fuels in motorsports offers a particularly attractive early niche market for investors," said David Still, the company's chairman.

The company's methanol has already been used in the experimental Lotus Exige 270E Tri-Fuel sports car.

There is one little caveat, however.

Energy has to be added into the process at several stages. Turning water into hydrogen and oxygen, in particular, is a highly energy-intensive process.

That's why hydrogen is such a good energy carrier: It strongly wants to bond with other molecules, giving off high amounts of energy as it does so (hence its potential as a vehicle fuel).

And the energy added into this process has to come from somewhere.

As New Scientist notes, this will only be truly carbon-neutral gasoline if all that energy comes from renewable sources like solar, wind, or hydro.

If electricity from dirty coal-burning powerplants is used to turn atmospheric carbon dioxide into gasoline, then the process is far from carbon-neutral.

So before we hail the arrival of truly green gasoline, we'd like to know how the company plans to ensure that only renewable energy is used in any such plants.


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Comments (10)
  1. Interesting.

    So we are converting KWH to liquid fuels which presumably is a less than 100% efficient process.

    Next we are converting our liquid fuel into torque in an ICE, with is a very inefficient process. So the conversion efficiency from KWH to Torque might be very poor compared to an EV.

    Of course, the nice thing with liquid fuels is that you don't have heavy limiting batteries to drag around.

  2. Sodium hydroxide doesn't magically appear either. It is produced by the chloralkali process, which "has a high energy consumption, for example over 4 billion kWh per year in West Germany in 1985".

    No thanks.

  3. As far as I understand the process, the sodium hydroxide is not being consumed. It is used to capture the CO2 from the air, and reused again and again. So how much energy it costs to make it does not really matter.

  4. John, This is a novel idea. Keep reporting on the new ones. The answer to our future problems lies in fuels, not in auto manufacturers. This is a good catch on your part. With the RFS standards ramping up, there will be a lot of fuel experimentation.

  5. First place I heard of this was at Kirk Sorensen's Ted talk about LFTRs.

  6. This will only "solve" oil security issue, but it won't solve Energy issue or energy efficiency issue.

    It sounds to me that the entire system is a very energy inefficient especially if the end results is about to fuel a 20% efficient ICE...

  7. Oh, this is also NOT too different from Navy working on generating fuel from sea water...

  8. While this will not be carbon neutral in the short term, it maybe less impactful than extracting hydrocarbons from the ground. There is no magic perfect solution.

  9. It just sounds like a waste of time, if it takes a massive amount of energy to make and keeps us drilling for oil, what good is it? So it makes the refining process a bit cleaner, big deal. Honestly is sounds more like an ethanol replacement then a revolution.

  10. The only use I can envision for this kind of process is in the distant future where solar PV is so cheap that it generates enormous amounts of superfluous electricity in the summer, too much to use immediately.

    That energy could be used to produce a hydrocarbon fuel to power a thermal power station and generate electricity in winter. When the fuel is methane, that process could conceivably have an acceptable roundtrip efficiency (due to the >60% efficiency of CCGT's).

    If the alternative is to throw away summer overproduction, any efficiency is good enough.

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