Poo power starts at Hampshire zoo

Marwell Zoo has become the first of its kind to generate renewable energy using animal waste.

Zoo poo from endangered species such as Grevy’s Zebra, Scimitar Horned Oryx and Somali Wild Ass will heat the park’s largest buildings using biomass technology.

The world-first Energy for Life initiative saves 220 tonnes of CO2 equivalent each year and marks a critical step in the conservation charity’s goal to become carbon neutral next year.

Dr Duncan East, Head of Sustainability said: “Using heat in this way from our own animals is unique in the UK and as far as we know across the world. The urgent need to reduce the burning of fossil fuels and leave these high carbon sources in the ground means we can’t act soon enough to replace the oil-fired heating systems in these buildings

“Previously 600 tonnes of animal waste was taken off-site to be composted, and this came with a significant carbon transport cost. We came up with the idea of biomass heat generation to reduce our carbon footprint and turn a previous waste stream into a valuable resource – achieving cost savings in the process.”

Since the Energy for Life: Tropical House opened in 2018, Marwell has been working with experts to build a solution using a blend of different technologies so the zoo’s unique animal waste can be processed into briquettes to fuel the new biomass boiler efficiently.

Zoo keepers sweep up the zoo poo from the animal paddocks and enclosures each morning before a mini refuse truck collects the waste and transports it to the Energy Centre.

A digger transfers the mixture of manure and bedding to a shredder for mixing, before it is then dried and pressed into briquettes, which are fed into the boiler.

The boiler produces hot water which is fed into a 15,000 litre thermal store, before flowing underground to heat the zoo’s latest exhibit, its Energy for Life: Tropical House, which combines the tropical animal habitat with educational exhibits on energy flow, climate change and powering modern lifestyles. Here, its resident animals including a Linne’s two-toed sloth, free-flying tropical birds and crocodile monitor lizards as well as its lush tropical plants benefit from the warm humid environment.

Its roof is made from the latest ETFE ((Ethylene tetrafluoroethylene) technology which offers natural light and provides good insulation and rainwater is harvested from the roof to water the plants within.

The next phase of the biomass system is to provide heat to other buildings across the zoo and will benefit the okapi, primates in Life Among the Trees and Marwell staff who work in Grade 1 Listed Marwell Hall.

Dr East, said: “Replacing oil fired heating system with heat generated from waste from our own animals will hugely reduce our carbon footprint, and what better way than to make use of a material which is in abundant and continuous supply.”

Since 2008, Marwell has reduced its carbon output by 77% and champions renewable schemes in the local community.

Marwell manages its own land both within the zoo and in the surrounding fields and woodland both to improve the biodiversity of native wildlife and to produce hay and browse (young leafy shoots) to feed to the animals. After eating, the waste from the animals is burnt for heat and the ash added to our compost process and then returned to the land.