Advanced BioFuels USA

by Jim Lane (Biofuels Digest)  A technology for direct air capture of carbon dioxide from the atmosphere, with a cost that “fully burdened with interest on capital, ranges from 94 to 232 $/t-CO2 depending on financial assumptions, energy prices, and the specific choice of inputs and outputs,” was the subject of a dense, highly detailed paper published today in a newish energy journal, Joule.

Direct Air Capture is no small thing. The problem with CO2 concentration is that it is too high to support a cool climate, but too low to be easily Hoovered from the sky. The concentration we are worried over is 400ppm, that’s 400 parts per million. That means you have to capture 2500 tons of air for every ton of carbon dioxide — and right there, that’s the reason we have left the job of capturing carbon to plants — not industrial plants, just the garden kind. Flowers work for low wages.

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As has been the case with many advanced biotechnologies, they work, but they cost more than gasoline, and the public doesn’t support higher costs for long, if ever.

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Prior to this, no paper we’ve seen for direct air capture has had all its major components drawn from well-established commercial engineering heritage, or been described in sufficient detail to allow assessment by third parties.

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So, from a cost and detail POV, we may find ourselves at a watershed moment that matters greatly to supporters of algae technology, solar fuels (made from CO2, sunlight and water), electrofuels (made from CO2, water and renewable electricity), or those in favor of scrubbing the atmosphere of enough of this pesky CO2 to reduce the impact of climate change.

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As Keith (Carbon Engineering’s David Keith) explained to The Digest, “beyond carbon removal, DAC can be used to make carbon-neutral hydrocarbon transportation fuels, a concept we call “air to fuels”. This is Carbon Engineering’s near-term business focus. We use DAC as a source of atmospheric CO2 to enable carbon-free renewable power to be converted into high energy-density fuels. Solar fuels, for example, may be produced at high-insolation low-cost locations from DAC-CO2 and electrolytic hydrogen using gas-to-liquids technology. This allows displacement of fossil fuels from difficult-to-electrify sectors such as aviation. When integrated into an air-to-fuels process the cost of DAC can be less than 100 $/t-CO2—a price point that enables commercial production of synthetic fuels in today’s low-carbon fuel markets. We have demonstrated the compete air-to-fuels process at our pilot plant.”

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On the negative side, the conversion efficiency — a lot of potential energy is lost or expended in the conversion to fuels.

But there are some avoided negatives, too. For example, the difficulties and costs of changing to mass-scale battery electrical vehicles, the infrastructure cost. Plus, batteries have inefficiency problems too. It has been claimed elsewhere — and Michael Tamor, a Henry Ford Technical Fellow at Ford, ruminated on this topic at a recent DOE Bioeconomy event in Washington — that at least double our current electrical power capacity will be required to be able to charge all battery electrical vehicles. Also the recycling of batteries and its LCA effects remains an issue.

In the end, here’s the great advantage, and it’s infrastructure. With batteries, you have to rebuild the fleet, rebuild the energy delivery system, and rebuild the grid. Fail in any of those and you’ve failed to change the carbon picture. Each of them is massive — together, it’s the biggest industrial transformation ever attempted.

With liquid fuels, you have just the one transition, and that’s the replacement of the energy supply, so long as drop-ins are used. And there’s gradualism — there’s a transition to better energy supply today — and possibly to fuel cells down the line where you get electric motor efficiencies added to the mix.

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More recently, we profiled that Climeworks opened its first small commercial plant near Zurich, and will capture around 900 tons of CO2 per year. A great step but a tiny one — it would take 25 million of these to capture the world’s annual CO2 emissions, the inventors say.

And here, the Carbon Engineering team demonstrated “Air to Fuels” by directly synthesizing a mixture of gasoline and diesel using only CO2 captured from the air and hydrogen split from water with clean electricity.  READ MORE