Air travel is among the most carbon-polluting human activities, but companies are trying—again—to lower their climate impact with biofuel. LongReads
It’s a painful truth for people who fly: Airplanes are climate killers. Air travel is among the most carbon-polluting human activities. A round trip from New York City to London emits nearly 1000 kilograms of carbon dioxide per passenger, more than an average person in Burundi, Nicaragua, or 47 other countries emits in a year. Annually, airplanes spew some 920 million tons of CODerek Vardon is hoping a yellowish, foul-smelling liquid will help change that.
For now, SAF producers create just 100 million liters of fuel per year for an industry that consumed more than 360 billion liters in 2019, before the pandemic cut that in about half. By 2030, the market for SAFs may grow by 70-fold, to nearly $15.7 billion, according to Markets and Markets. The recipe for cellulosic ethanol seemed like a winner. Start with farm and forest waste that is so abundant it is essentially free, use microbial enzymes to convert it to sugars, let yeast ferment the sugar, and you’ve got a fuel you can sell. The climate case was equally compelling. Compared with fossil fuels, corn-derived ethanol reduces CO emissions by 20% to 40%; ethanol made from waste biomass cuts emissions by 90%.
McAfee is betting Aemetis won’t be among them. He’s building a large chemical facility in the middle of Northern California’s almond orchard country. Almond farmers typically replace their trees every 15 to 25 years. That creates more than 2 million tons of agricultural waste per year. Farmers used to burn it, but the practice is being phased out to improve the region’s air quality.
The activity extends beyond industry to a consortium of nine U.S. national labs, which BETO has funded to come up with technologies that could aid many different SAF pathways. Among the projects: developing artificial intelligence to find combinations of enzymes and catalysts that break down waste at lower temperatures than existing versions and exploring whether converting municipal solid waste to tiny pellets will simplify processing steps.