Two separate studies have demonstrated the potential of human waste as both an energy source and fertiliser.
Finnish scientists found that human urine together with wood ash could act as an alternative fertiliser for tomatoes.
Surendra Pradhan and his colleagues from the University of Kuopio found that the urine/wood ash combination increased the yields of tomatoes in comparison to non-fertilised plants.
They also produced equal amounts of tomato fruits as mineral fertilised plants without posing any microbial or chemical risks.
In a separate development, scientists at Ohio University have developed technology to release hydrogen from ammonia compounds within urine. The hydrogen could be obtained from either human or animal urine.
The gas can then be burned or used in fuel cells to power cars or electrical devices.
The team is now trying to commercialise the technology and bring it to the mass market.