Human and other animal faeces is generally considered waste, but – like forestry and agricultural waste, landfill gas, and sewage sludge – it can be repurposed as a fuel. As bacteria digest faeces, they produce a methane-rich biogas that can be burned for energy. Alternatively, faeces can be dehydrated and packed to produce combustible bricks (biochar or hydrochar) with a similar energy content to coal. ‘Poo power’ is an established technology in wastewater plants all around the world.
At Marwell Zoo in Hampshire, waste from a range of the zoo’s endangered species – including Grevy’s zebra, the scimitar horned oryx, and the Somali wild ass – will be used as feedstock for biofuel. The fuel will be used to heat the zoo’s largest buildings, including its tropical house.
The “Energy for Life” scheme, which will save the equivalent of 200 tonnes of CO2 annually, is a key part of its aim to become carbon neutral by next year.
The zoo will be the...