Carbon-neutral fuel

[10] Synthetic hydrocarbons can be produced in chemical reactions between carbon dioxide, which can be captured from power plants or the air, and hydrogen.

To minimize emissions, the electricity is produced using a low-emission energy source such as wind, solar, or nuclear power.

[12] Through the Sabatier reaction methane can then be produced which may then be stored to be burned later in power plants (as a synthetic natural gas), transported by pipeline, truck, or tanker ship, or be used in gas to liquids processes such as the Fischer–Tropsch process to make traditional fuels for transportation or heating.

The stored energy can be recovered by burning the methanol in a combustion engine, releasing carbon dioxide, water, and heat.

[5] The most economical source of carbon for recycling into fuel is flue-gas emissions from fossil-fuel combustion where it can be obtained for about US$7.50 per ton.

[24] In 2010, a team of process chemists led by Heather Willauer of the U.S. Navy, estimates that 100 megawatts of electricity can produce 160 cubic metres (41,000 US gal) of jet fuel per day and shipboard production from nuclear power would cost about $1,600 per cubic metre ($6/US gal).

[needs update] Moreover, since the delivery of fuel to a carrier battle group costs about $2,100 per cubic metre ($8/US gal), shipboard production is already much less expensive.

[30] Because the process requires a large input of electrical energy, a plausible first step of implementation would be for American nuclear-powered aircraft carriers (the Nimitz-class and the Gerald R. Ford-class) to manufacture their own jet fuel.

[26] In 2023, a study published by the NATO Energy Security Centre of Excellence, concluded that e-fuels offer one of the most promising decarbonization pathways for military mobility across the land, sea and air domains.

[32] A 250 kilowatt methane synthesis plant was constructed by the Center for Solar Energy and Hydrogen Research (ZSW) at Baden-Württemberg and the Fraunhofer Society in Germany and began operating in 2010.

[33][34] The George Olah carbon dioxide recycling plant (named after George Andrew Olah[35])operated by Carbon Recycling International in Grindavík, Iceland, has been producing 2 million liters of methanol transportation fuel per year from flue exhaust of the Svartsengi Power Station since 2011.

[38] The plant is intended to produce transportation fuel to offset LNG used in their A3 Sportback g-tron automobiles, and can keep 2,800 metric tons of CO2 out of the environment per year at its initial capacity.

Commercial developments are taking place in Columbia, South Carolina,[41] Camarillo, California,[42] and Darlington, England.

[43] A demonstration project in Berkeley, California, proposes synthesizing both fuels and food oils from recovered flue gases.

[45][19][46] Such recycling is expected to not only cost less than the excess economic impacts of climate change if it were not done, but also to pay for itself as global fuel demand growth and peak oil shortages increase the price of petroleum and fungible natural gas.

[16] It is possible to convert methanol into gasoline, jet fuel or other hydrocarbons, but that requires additional energy and more complex production facilities.

[50] Fuel made from microalgae could potentially have a low carbon footprint and is an active area of research, although no large-scale production system has been commercialized to date.

Although they, unlike most plants, have extremely simple cell structures, they are still photoautotrophic, able to use solar energy to convert carbon dioxide into carbohydrates and fats via photosynthesis.

The advantages of microalgae are their higher CO2-fixation efficiency compared to most plants[52] and their ability to thrive in a wide variety of aquatic habitats.

Raceway pond systems are constructed by a closed loop oval channel that has a paddle wheel to circulate water and prevent sedimentation.

[51] The pond needs to be kept shallow since self-shading and optical absorption can cause the limitation of light penetration through the solution of algae broth.

Another thing that needs to be acknowledged is that environmental impacts can also come from water management, carbon dioxide handling, and nutrient supply, several aspects that could constrain system design and implementation options.

However, when compared with electrification of the vehicle fleet – a key advantage of such biofuel is the avoidance of the costly distribution of large amounts of electrical energy (as is required to convert existing vehicle fleets to battery electric technology), therein allowing for the re-use of the existing liquid-fuel transportation infrastructure.

Biofuel such as ethanol is also greatly more energy dense than current battery technologies (approximately 6x as much[56]) further promoting its economic viability.

The construction of large-scale microalgae cultivation facilities would inevitably result in negative environmental impacts related to land use change, such as the destruction of existing natural habitats.

If poorly managed, toxins naturally produced by microalgae may leak into the surrounding soil or ground water.

A 1965 report suggested synthesizing methanol from carbon dioxide in air using nuclear power for a mobile fuel depot.