Fly me to the moon: rocket fuel made from human waste

Researchers in Florida have developed a method for converting human waste into rocket fuel. They believe they can produce enough fuel to fly from the moon back to earth.

University of Florida engineer, Prof Pratap Pullammanappallil and grad student Abhisshek Dhoble showed they could produce 290 litres of methane per crew member per day by sending their poo into an anaerobic digester.

The US National Aeronautical and Space Administration commissioned the study in support of its goal to establish a manned facility on the moon between 2019 and 2024. The question was what to do about the waste from all those astronaut rations.

Disposing of this stuff of course is no joke. There was no question of dumping it on the lunar surface. The current practice involves storing it and then allowing it to burn up on reentry to the earth's surface.

Nasa also had the idea that it might be possible to reduce the weight of spacecraft bound for the moon if they didn't have to carry all the fuel needed for the return journey.

A problem in search of a solution found one in the case of Prof Pullammanappallil's digester. The two researchers set out to measure how much methane they could get by putting the waste in at one end and taking biogas off at the other. They found they could get quite a lot, publishing their findings in the journal Advances in Space Research.

Biogas is a mix of methane and carbon dioxide. "Methane can be used to fuel the rockets. Enough methane can be produced to come back from the moon," the professor says.

The digestion process also delivered more than 270 litres of undrinkable water, another form of waste that has a use. An electric current is enough to split the water into hydrogen and oxygen, with the oxygen being used to sustain the moon people.

And nothing gets wasted. The carbon dioxide from the digester can be combined with the split hydrogen to make even more methane and water, the authors say.

The same digester could do service on earth, providing fuel for heating, power generation and transportation, says the professor. “It could be used on campus or around town or anywhere to convert waste into fuel.”