If you have dreams of one day living on the International Space Station (ISS), start wrapping your head around the idea of drinking your own pee. In space, every drop of water is a precious commodity so it doesn’t make sense to literally flush it down the toilet. Luckily, the process of recycling water from urine isn’t nearly as gross as it sounds. The water is drawn out from the urine so efficiently that none of the “source liquid” shows up, taste-wise. Urine recycling systems have been in use on the ISS since 2008, but it is only recently that new systems are being developed that could yield both water and energy from human liquid waste.
Eduardo Nicolau and his team at the University of Puerto Rico have developed a system for a urine processor that could allow those non-water urine components to actually generate electricity. It would go something like this: First, the water would be pulled out of the urine using forward osmosis*, which uses a concentrated salt (or sugar) solution to separate the water from the other chemicals in the urine. The urea that is left over from this is then mixed with enzymes which convert it into ammonia. This ammonia can then be put into an electromagnetic cell which can use it to generate electricity.
When wastewater is not recycled, it’s jettisoned out into space. These dumps can sometimes be seen from Earth, as this piss-comet was in March of 2011. (Jens Hackmann/kopfgeist.com)
The new system is far from perfect as of yet – it doesn’t yield much electricity and requires precious oxygen to operate – but converting urine into water and power will be crucial for longer space flights like a mission to Mars. Without recycling urine, water reserves would take up 80-90% of a ship’s mass on a trip to Mars. At an absurdly pricey $10,000 per pound, launching that much water into space would make a mission without drinking piss-water prohibitively expensive.
HT: Science News