Poop to power planes

A new way to produce sustainable fuel

Some scientists have demonstrated the ability of “wet” human waste, like rotting food and sewage, to power airplanes. The recycled fuel could reduce airline emissions and waste, creating a “165% reduction” overall, according to scientists, which is about 4% of total greenhouse gases.

The secret is volatile fatty acids (VFA), converted from a waste product into paraffin, a popular combustible jet fuel ingredient.

“Over 21 billion gallons of jet fuel are consumed in the United States annually, with demand expected to double by 2050”, researchers from the U.S. National Renewable Energy Laboratory (NREL) explained.

“Sustainable aviation fuels (SAF) comprise a significant portion of the aviation sector’s strategy for CO₂ reductions given the limited near-term prospects for electrification. In addition, the low aromatic content of current SAF routes has been shown to reduce soot formation and aviation-related aerosol emissions by 50 to 70%. Soot is the primary nucleator of contrails, which have a larger effective radiative forcing (57.4 mW/m²) than aviation-emitted CO₂ alone (34.3 mW/m²)”, they added.

The problem in reducing airline emissions is that it’s much harder to develop an alternative fuel source plane than for consumer vehicles on the ground. But there’s an upside: jet fuel has lower purity requirements than gasoline for cars.

Wet waste includes everything from flushed toilet water, to rotting food waste, including your poop. It’s typically biodegradable but still generates further waste, like the methane generated by landfills. This is harvested, but the process is inefficient. In their new study, the NREL scientists describe draining wet waste of water and then catalyzing it into fungible hydrocarbons for airplane fuel.

In doing so, the new way to extract and blend resulted in more efficient, better-burning jet fuel that can safely replace a higher percentage of hydrocarbons in the final blend. To do this, the scientists took wet waste that’s typically turned into methane and slowed the process so that more complex hydrocarbons emerged which is a huge improvement with reasonable costs: “Techno-economic analysis for VFA catalyst upgrading determined VFAs can be produced at $0.30/kg to achieve a Fast Track minimum fuel selling price of $2.50/gallon”, scientists explained.

There’s enough viable wet waste to replace 20% of overall airplane fuel, which also means diverting the wet waste from the methane-producing landfill cycle. This is how the reduction in emissions goes past 100% to 165%.

One more time, poop is the key to sustainability.

Source popularmechanics.com