Presidential Green Chemistry Challenge: 2014 Small Business Award
Farnesane: a Breakthrough Renewable Hydrocarbon for Use as Diesel and Jet Fuel
Summary of Technology: Transportation is second only to generating electricity as a source of greenhouse gas (GHG) emissions in the United States. Gasoline consumption by automobiles is responsible for more than half of all greenhouse gas emissions from transportation, while other uses, such as diesel fuel for trucks, trains, or maritime use and jet fuel for aircraft, account for the remainder. Increases in fuel prices have led many countries, including the United States and Brazil, to begin modern large-scale production of biofuels. Locally-produced biofuels have the potential to be a significant contributor to global sustainability, including providing local employment, ensuring access to energy resources, and reducing GHG emissions.
First generation biofuels, notably ethanol and biodiesel (i.e., fatty acid methyl esters), suffer from limitations, such as limits on how much can be blended with gasoline or poor cold-weather performance. To address the known shortcomings of first generation biofuels, Amyris developed an advanced renewable fuel compatible with the existing vehicle and distribution infrastructure that is now used in heavy-duty diesel engines and commercial aircraft.
Amyris used state-of-the-art strain engineering to make yeast that converts sugars into the hydrocarbon farnesene rather than ethanol. Farnesene can then be hydrogenated to farnesane, a renewable drop-in replacement for petroleum diesel and a blend-stock for jet fuel. A recent lifecycle analysis estimated an 82 percent reduction in GHG emissions for farnesane, compared with the EPA baseline fossil diesel—including indirect effects. Farnesane can also have land-use benefits for heavy-duty transportation: a hectare of land growing soybeans to produce traditional biodiesel generates enough fuel for a bus to travel about 600 miles. If the same land is instead used to grow sugarcane to make ethanol, a bus adapted to run on ethanol could travel about 4,000 miles. However, if the sugarcane is used to produce farnesane, the unmodified diesel vehicle can travel about 5,500 miles. Breakthroughs in converting lignocellulosic biomass to fermentable sugars will further increase this benefit.
Amyris has demonstrated industrial-scale production using its proprietary yeast strains to ferment sugars into renewable fuels that meet petroleum fuel specifications. Its renewable diesel, which has been approved by EPA for blends up to 35 percent, contains no sulfur or particulates, has a higher cetane number than diesel, and has improved low-temperature performance. More recently, in June 2014, ASTM revised its standard for jet fuel to include the use of renewable farnesane as a blending component in jet fuels for commercial aviation.
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