The residents of Pachacamac, a Peruvian village outside Lima, have almost one thousand fluffy, tailless guinea pigs in an enclosure. They’re not pets though: instead, the animals are a source of renewable energy that powers the entire town.
Green solutions like wind power, tidal turbines and solar panels aren’t always feasible for smaller, less developed countries. For more practical results, professors Carmen Felipe-Morales and Ulises Moreno invite scientists to their lab so studies in renewable energy and plant genetics can be used to make a fast, tangible difference to countries like Peru.
Alongside creating potatoes optimised for the village’s soil and climate, and developing several different types of organically produced fruits and cereals, the two scientists have an building, with low-roofs and several compartments, occupied by almost one thousand guinea pigs.
While the cute rodent is a popular domesticated pet in Europe and North America, it’s an even more popular menu option for residents of the Andes range in South America, where the guinea pig originated and where these Peruvian villages can be found.
Before you get images of hamster-wheel factories of exhausted rodents, all the animals have to do is munch on their diet of specially enriched plant waste, and then poop it out. The small, dry pellets are then fed into a bio-digester that's based on a Chinese model, but adapted by Moreno. Water is added, and the result is both methane gas and a brown liquid plant nutrient.
Wandering Gaia reports that the efficient process, plus the three tonnes of excrement that’s produced each month, generates more than enough gas for the scientists’ use (such as gas-powered light bulbs and stoves, and even an electric generator for TVs and computers), plus plenty of compost and liquid plant feed that can be used or sold to locals.
The team produces three cubic metres of methane a day and 50 litres of the liquid nutrient a week. The village sells the plant food for 2 soles (about 45p) per litre, compared to the industrially produced equivalent that costs 150 soles (about £35) per litre.
The use of animal poop as an energy source isn’t just limited to the developing world, though. Zoos around the world, from the Rosamond Gifford Zoo in New York to Paignton Zoo in Devon, are using dung to cut costs and carbon emissions. Think three tonnes of energy-filled poop from 1000 guinea pigs a month is impressive? Try two elephants, which can produce two tonnes of dung a week!