Green Fuels: What to Expect Now and in the (Far) Future

Some mobility tasks just cannot practically be electrified—those involving extreme loads, harsh climates, or long range where refueling/recharging is impractical require the energy density that only a liquid hydrocarbon fuel can deliver. Fortunately, science is delivering carbon-neutral fuel options.

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Now or Coming Soon

Biofuels were the original mobility decarbonization concept. Ethanol was an early option for “growing” fuel, where the feedstock would absorb CO2 while growing. But when making ethanol from corn, the fuel simply displaced corn destined for food—either directly or via livestock feed, meaning no new net CO2 was absorbed. Cellulosic ethanol is a different story, as it’s made from the otherwise unusable lignin in corn stalks, from grasses, or from myriad waste products—things that would otherwise simply rot, releasing their CO2. But to date, none of the bioengineered franken-microbes, catalysts, or manufacturing processes can compete profitably with comparably cheap oil.

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Biobutanol vs. Ethanol

Biobutanol is even more attractive than ethanol because it’s a near drop-in replacement for gasoline. Promising research continues into treating a stream of CO2 gas with bioengineered microbes and hydrogen to produce biobutanol that’s as clean as the hydrogen that created it. Green hydrogen production using coffee grounds and spirits-distilling byproducts has shown promise.

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Obrist Modern Forest Schematic

Methanol was once proposed as an alternative or gasoline-blending fuel, but its higher toxicity and corrosive effect on aluminum effectively shut it out. It can be produced more sustainably than ethanol and can be produced directly from CO2 and hydrogen, making it an important stepping stone in many carbon-capture green-fuel schemes. Austrian firm the Obrist Group proposes large solar farms located in deserts near sea water to employ direct carbon capture plus electrolysis, with a related reaction sequestering carbon as graphite in the process. By using renewable energy and incorporating this carbon sink, Obrist claims its eMethanol is the world’s first carbon-negative fuel. Obrist is short on specifics as to when production might start—figure between two years and never.

Within a Decade

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HIF Global Porsche Fuel Schematic

The eFuels, or electrochemical fuels, that will allow us to keep driving our beloved combustion cars use electrical energy to construct fuel molecules using CO2 from the atmosphere and hydrogen electrolyzed from water. Porsche is running its racing program on 100 percent carbon-neutral e-gasoline today, all of which is produced using direct carbon capture powered by wind. HIF Global’s Haru Oni eFuels demonstration plant is up and running, powered by a 3.2-megawatt wind turbine. It produces about 35,000 gallons of eFuel per year, priced at about $45/gallon. HIF has applied to install 384 MW of wind turbines, with a goal of combining 250,000 tons of CO2 with hydrogen from sea water to make 17 million gallons of eFuel per year at more reasonable prices.

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Prometheus Titan Fuel Forge 

Prometheus Fuels claims its process short-circuits some of the more energy-intensive steps in HIF’s process to achieve price parity with petro fuel. Its catalytic electrolysis produces ethanol from a solution of CO2 in water then separates the ethanol via a carbon-nanotube membrane, saving the energy of distillation. Stated production deadlines have passed, but BMW i Ventures is invested and apparently remains bullish.

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Carbon Capture image

Carbon Engineering was early to the fuel-from-CO2 game in 2018, leveraging proprietary paper-mill technology, but its recent acquisition by Occidental Petroleum calls into question future fuel production plans.

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Nacero

Houston-based Nacero planned to construct gasoline from methane that would otherwise be flared at oil fields, making it essentially carbon neutral if converted using green energy. But this year it shifted focus to producing airplane fuel using NextEra Energy Resources wind and solar energy.

Automobility may find itself standing in line behind aviation for green fuels. That market will bear higher pricing and has fewer options for decarbonization—there’s just no powering a transatlantic jumbo jet with batteries.

Interstate trucking is another area where batteries may never pencil out, but White House plans to fund a national zero-emission freight corridor may allow hydrogen to decarbonize freight transport in the next decade, either via fuel cells or by burning it in diesel engines.

Farther Out

Expect tomorrow’s planes, trains, ships, heavy trucks, and vintage cars to be powered by a variety of green fuels. The real lynchpin to viable, sustainable production of green fuel is readily available and affordable green energy. Where might that come from?

Thorium

Watch for simpler, safer thorium-powered pebble-bed nuclear reactors sized to supply a neighborhood or an industrial facility.

And recent experimental successes suggest science is gradually figuring out how to harness the sun’s internal source of power via nuclear fusion. That might just sate our seemingly insatiable global appetite for clean energy once and for all.