Designer Yeast Makes Renewable Jet Fuel
Tom Lombardo posted on March 01, 2015 |

Legend says that pouring sugar into a fuel tank will cause engine problems. Apparently the engineers at Amyris didn’t get that memo, because they’re making jet fuel out of sugar cane. This renewable fuel has the same energy density as standard “Jet A” fuel, while offering three distinct advantages over petroleum-based jet fuel: a lower freezing point, fewer greenhouse gas emissions, and a renewable source.

Yeast is a living organism - a member of the fungi kingdom - that makes bread rise and provides the “magic” in our favorite potent potables. As brewers and winemakers know, most strains of yeast consume sugar and produce ethanol (alcohol) and CO2 as their byproducts; they top out at around 15% alcohol - not enough to use as fuel. Ethanol must be distilled in order to increase its alcohol concentration, and distillation uses energy.

Using a proprietary process called synthetic biology, Amyris has engineered strains of yeast that eat sugar and produce hydrocarbons such as farnesene (C15H24), which is then hydrogenated to produce farnesane (C15H32), a biodiesel and jet-fuel additive. Blending 10% farnesane with Jet A or Jet A-1 fuel results in a 3% reduction in pollutants from the engine exhaust and no degradation in fuel performance. Jet engines can run this blend without design modifications, and its use has been approved by regulatory agencies in the US, Europe, and Brazil. Experiments have shown that making jet fuel entirely out of the farnesane concoction would reduce pollutants by at least 60%, but today’s jet engines would need to be modified in order to run on that fuel, much like cars need modified engines to run on pure ethanol or E85.

Ultimately, Amyris hopes to develop strains of microalgae that use photosynthesis, water, and CO2 to produce oils that can easily be converted to biofuels. This would eliminate the need to grow a crop of sugar cane, making the fuel production process less costly and more environmentally-friendly.

Whether the fuel comes from yeast eating sugar or from microalgae performing photosynthesis, the resulting fuel is carbon-neutral. Although the fuel is burned, releasing CO2 into the atmosphere, sugar cane plants and microalgae both consume CO2, so it’s an even trade. Technically that disregards the energy used in farming sugar cane, but remember that drilling, transporting, and refining petroleum uses energy too. And unlike corn used for ethanol production, sugar cane uses less farming energy and virtually no pesticides or herbicides.

Jet fuel from sugar cane: renewable, clean, and carbon-neutral. Sounds like a sweet deal to me!

Images courtesy of Amyris

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