The average person produces between 800ml and 2,000ml of urine every day. Multiply that 7 billion times, and you end up with a huge volume: between 560 billion and 1.4 trillion liters of urine a day – down the drain.
What if that wasn’t wasted but instead used as a fuel?
Energy comes at a premium today. We are running out of fossil fuels at an alarming rate, and when we do burn them, we’re adding more and more greenhouse gases into the atmosphere, contributing to climate change. There’s increasing pressure for us to find new sustainable sources of energy, and bioenergy is one option.
It’s possible to produce bioenergy through processes like anaerobic digestion, fermentation and gasification. These are often carried out at large scale and can require high temperatures and pressures. Another option is microbial fuel cells, which turn organic matter into electricity by harnessing the natural processes of bacteria. They’re efficient, relatively cheap to run and produce less waste than the other methods.
Microbial fuel cells have real potential to produce renewable bioenergy out of waste matter like urine. Considering the huge volume of urine we produce, if we could harness its potential power using microbial fuel cells, we could revolutionize the way we make electricity.
So why aren’t we all using microbial fuel cells? One reason is they can be expensive to manufacture. Microbial fuel cells feature electrodes that collect the positive and negative charges that result from the bacteria breaking down the urine, turning the charge into electricity. The negative electrode – the cathode – often contains platinum to speed up the reaction, making the device cost more.
Also, microbial fuel cells tend to produce less power than the other methods of bioenergy production. It’s preferable for them to be smaller and therefore portable, but this limits their power output.
Researchers have come up with a new design to overcome these limitations, which you can read about here.
This article originally appeared in Electrochimica Acta, 192, 2016, Pages 89-98.
Electrochimica Acta is an international journal. It is intended for the publication of both original work and reviews in the field of electrochemistry.