Carbon-neutral synthetic fuel: A dream for car makers facing tighter standards

Bosch says synthetic fuels have potential to slow the release of CO2 into the atmosphere.

In a white paper released this month, German auto parts maker Bosch argued for increased development of carbon-neutral synthetic diesel and gas—that is, fuel made from carbon dioxide and (ideally renewable) electricity. Such fuel emits carbon dioxide when it's burned, but it also captures carbon dioxide as it's being made, so it's considered carbon neutral. Bosch researchers said moving to synthetic fuel could prevent the release of an additional 2.8 gigatons of CO2 in Europe between 2025 and 2050.

Synthetic fuels aren’t anything new, but they’re far more costly to produce than fossil-fuel-derived oil and gas. Fischer-Tropsch diesel is one kind of synthetic fuel that can be produced with carbon monoxide and hydrogen, creating a substance chemically identical to fossil fuel-based diesel. Another kind of synthetic fuel is made from oxymethylene ethers (OME), but OME fuel often requires retrofits to existing diesel engines before it can be burned in them, according to German broadcaster Deutsche Welle. Both are prohibitively expensive to produce compared to diesel made from fossil fuels.
But Bosch says investing in synthetic fuels is necessary to achieving Europe’s decarbonization goals. The company’s researchers also argue that the cost of synthetic fuel will fall with economies of scale and sufficient learning. “The transport sector has to achieve near-complete independence of fossil fuels by 2050 according to International Energy Agency models,” the Bosch white paper states. Long term, electrification could achieve this, but Bosch thinks that in the short timeframe we have, it may not be possible to replace the globe’s fleet (or even Europe's fleet) with electric and fuel cell vehicles.

Ellen Stechel, a senior sustainability scientist and the deputy director of Arizona State University’s LightWorks department, agrees that synthetic fuels are not only possible to make economic, but they're also necessary for reducing our dependence on fossil fuels. “Holding out for 100 percent electric light duty fleet is a little bit like making the perfect the enemy of the good,” Stechel said. “What people don’t think about is that with liquid fuels, you’re not carrying the oxygen that makes it react, so they’re very very energy efficient.”

She admits that synthetic fuels are expensive now but says the technology to produce them is there. “With research and advances and being to get on a learning curve” a fleet running on synthetic fuels is possible. “Like anything, there’s a barrier and it’s expensive when it’s low volume,” Stechel added. “I mean look at photovoltaic ten years ago.” (In 2000, the world had roughly four gigawatts of solar power capacity installed. By 2017, that number had exploded to 227GW.)

In Bosch’s paper, the researchers envisioned an international economy where regions of the world with plentiful renewable resources like wind could generate the power needed to produce H2. “The e-hydrogen can be used for fuel cell vehicles or synthesized by additional conversion steps to synthetic methane (e-CH4) or synthetic fuels for an increasing blend in the remaining gasoline and diesel fleet, not only for aviation and navigation but also for commercial and passenger vehicles,” Bosch wrote. The development of synthetic fuel from renewable energy essentially becomes a way to "store" that energy in places where wind, solar, or hydro power is less reliable.

New efforts

Bosch claims that “demonstration-level pilot plants are already ‘online’ today and industrialization is expected to be feasible within 5-10 years.” Although Bosch itself says it's not developing synthetic fuels, other companies and research centers are. Continental, another German automotive component maker, announced this month that it had completed tests using 15 percent OME synthetic fuel mixed with regular diesel.

"The current Continental road tests have confirmed that diesel fuel containing 15 percent OME admixture for current diesel engines is already a technically safe and viable possibility for reducing greenhouse gas emissions," the company writes. "This is possible because CO2 generated as exhaust gas in power stations or steel works can be used in the production of OME. This intelligent linking of energy management, chemistry and automotive sectors enables synthetic fuels such as OME to create a clean bridging technology on the road toward pure electric mobility.”

Bosch agrees that blending synthetic fuel with traditional fuel is the way to go. “With an assumed blend of 1 percent in 2025, 10 percent in 2030, 40 percent in 2040 and completely replacing the fossil fuel share by 2050, near net-zero emissions are achievable,” Bosch claims.

Similarly, the German Karlsruhe Institute of Technology (KIT) and the Finnish Lappeenranta University of Technology partnered to develop what they call the Soletair—a modular chemical plant that produces gasoline, diesel, and kerosene using Fischer-Tropsch synthesis from solar energy and ambient carbon dioxide. (Jamie Hyneman of Mythbusters fame was on the scene in Finland to announce the beginning of the project’s tests in June). “The pilot plant has a production capacity of up to 80 liters of gasoline per day. In the first campaign now completed, about 200 liters of fuel were produced in several phases to study the optimum synthesis process, possibilities of using the heat produced, and product properties,” KIT wrote in a press release.

The US is quite focused on biofuels from various crops (currently, a percentage of our gasoline is already blended with biofuel by government mandate), but synthetic fuels could remove the choice between using crop land for food and crop land for fuel. Still, synthetic fuel has had a rough go of it here in the states. Between 1980 and 1985, the US Government supported the Synthetic Fuels Corporation. But with the decline of oil prices, funding was cut. As carbon neutral or carbon negative fuel becomes an imperative under climate change, synthetic fuels' time may be ripening, at least abroad.