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NASA explores potential of human waste as rocket fuel

Determined to build an inhabited facility on the moon’s surface between 2019 and 2024, NASA has run into a problem: What to do with the human waste? Dumping it on the moon was not acceptable, so the agency turned to academic researchers to figure out how to turn it into fuel for future spacecraft to journey from the moon back to Earth.

The University of Florida scientists tasked with innovating a process have focused on ways to turn the waste into methane gas.

“The idea was to see whether we could make enough fuel to launch rockets and not carry all the fuel and its weight from Earth for the return journey,” said Pratap Pullammanappallil, a UF associate professor of agricultural and biological engineering who teamed up with then-graduate student Abhishek Dhoble. “Methane can be used to fuel the rockets. Enough methane can be produced to come back from the moon.”

Pullammanappallil and Dhoble – now a doctoral student at the University of Illinois – reported their fundings in a study published in the November issue of the journal Advances in Space Research, according to Southeast Farm Press.

The chemically produced waste given to them by NASA included simulated food waste and packaging materials, and the duo discovered that up to 290 liters of methane could be produced, per crew per day.

The process involves an anaerobic digester that kills pathogens from human waste and creates biogas, a combination of methane and carbon dioxide. The biogas can be applied for heating, electricity generation and transportation purposes on Earth – not just in space.

The scientists determined the digester can also produce 200 gallons of non-potable water annually from the waste, which can be split into hydrogen and oxygen through electrolysis, providing astronauts with additional oxygen in a back-up system. The exhaled carbon dioxide and hydrogen can be converted to methane and water in the process.