On the quiet city of Malvern Hills, next to where England meets Wales, Brian Harper noticed that his neighbors would walk their dogs every day to the city’s central park, so that their pets could answer Mother Nature’s call. Harper then thought it could be possible for all that organic matter to be useful and valuable – and he was right.
In 2015, Harper started developing the idea of turning dog poop into some sort of energy supply. That’s not something new, though. Manure can also serve as fuel. There is evidence that our ancestors were used to generate energy through organic matter since the Neolithic era. The system to transform that sort of material into flammable gas has been around since the 17th Century.
Ben Harper’s invention follows the same criteria, but with a higher degree of efficiency and without generating environmentally-dangerous gases. Only a single lamp is powered by the animals’ waste at Malvern Hills’ central park, but the technology is expected to be embraced soon by more and more green areas in the United Kingdom.
“The gas light captures people’s imagination and shows them dog poop has a value,” said Harper in an interview for British paper The Guardian. “As a result, we get it [poop] off the ground, into a receptacle, and produce something useful” he completed.
How does the manure system work?
It’s quite simple: When the citizens of Malvern Hills are walking their dogs around the park, they should collect their feces and put them in a green bin right next to the street lamp, which sustains not only the light bulb itself, but also its small energy power plant. The matter is then decomposed by anaerobic micro-organisms, producing fertilizer and methane, a flammable gas.
Turning dog poop into light
- The dog’s owner places the animal’s disposables into a plastic or paper bag;
- He/She turns a hand crank five times, making the machine send the matter to a biodigester, where microbes decompose it;
- In a process that takes a few days, biogas is then produced, composed by 60% methane and 40% carbon dioxide, which stays stored on site;
- When night comes, the street lamp itself, through a sensor that detects light variation, turns on the gas supply, which releases the exact amount of fuel to generate power and turn on the light.
The town's government set up the equipment in November 2017. According to Brian’s project, the system needs to be fed with ten bags of feces to keep the lights on for two hours.
Similar systems in other countries
Waterloo, in Canada, is coming up with a similar strategy to find a sustainable use for animals’ feces. The town’s government has installed a concrete structure to store the material in one of its parks. This storage is periodically emptied by trucks, which take the matter to a big central power plant. There, the material is mixed with other sorts of organic matter and then decomposed, generating methane, and therefore, energy. Fertilizer is also produced from this process, and then sold to farm owners.
According to civil servants responsible for the system’s set up, the primary goal is not only to produce large-scale energy, but also to improve the city’s garbage collection system. “Collecting dog waste separately prevents it from contaminating our recycling streams, allowing us to divert both away from our landfill sites,” said Jeff Silcox-Childs, Waterloo’s director of environment and parks, to The Guardian. On the first five of a total 18 months of tests, the system was able to provide power to 13 houses and to remove 630 kilograms of CO2 from the atmosphere.
In India, the use of biodigesters has been happening for a while now, usually fueled with bovine manure. Technology is also seen there as a possible large-scale solution to help reduce public defecation.