The power of poo: energy from excrement

Portland, Oregon, USA

The Bureau of Environmental Services for Portland has a great system in place to make the most of its waste. The city’s sewage is usually decomposed into methane gas, which is captured by their wastewater plants and turned into energy and electricity. Yet there are now plans to partner up with Northwest Natural Gas and sell the remaining converted effluent as a substitute for diesel fuel for cars, lorries and buses.

Back in April, the Portland City Council approved a $9m project to process the city’s sewer gas into marketable natural fuel. According to the Bureau, Portland’s two solid waste treatment plants use 77 per cent of the sewer’s methane to generate energy, and the remaining 23 per cent will be treated to create renewable energy to be processed as fuel for diesel vehicles.

The Bureau says the new facility can produce natural gas to power the equivalent of 154 bin lorries.

Ladner, British Columbia, Canada

Farmer Jerry Keulen from SeaBridge Farm is turning manure from his cows into reusable energy. In fact, he is one of many North American farmers taking advantage of their livestock’s poo by using a mini anaerobic digester to break down waste into renewable natural gas (RNG). Keulen has support of electric power and gas distribution company Fortis BC.

Purifying the gas means that it could be put into the Fortis BC system, fundamentally replacing natural gas altogether. This year, the provincial government endorsed RNG as part of its climate leadership plan. Rich Coleman, Deputy Premier and Minister of Natural Gas Development, said: “We are creating market opportunities for British Columbia’s natural gas sector, offering utilities flexibility to create new incentive programs so we can continue to build a strong economy and a cleaner future.”

California also has a ‘Dairy Manure Digester Development’ programme and, so far, there are 16 dairy digester operations in that state.

Grand Junction, Colorado, USA

The Persigo Wastewater Treatment Plant is processing eight million US gallons of human waste into biomethane, or RNG. This gas fuels about 40 public service vehicles such as street sweepers and buses.

The project, which is worth $2.8m, could reduce greenhouse gases by as much as 80 per cent and has been developed for over a decade.

Raw biogas collected from the anaerobic digestion plant is upgraded to RNG, and can be used as heat, fuel or electricity.

The underground pipeline is almost six miles long and carries the compressed RNG from the wastewater plant to the city’s fleet fuelling station. It’s estimated that about 460 gasoline gallon equivalents (GGEs) will be produced on-site every day.

Detroit, Michigan, USA

Back in October, the Detroit Zoological Society (DZS) was nearing completion of its anaerobic digester, which will convert more than 400 tonnes of animal manure into renewable energy. This will power the zoo’s Ruth Roby Glancy Animal Health Complex. The left-over compost will be spread on the zoo’s gardens and donated to the community.

DZS is the first zoo in the country to have an anaerobic digester, which will also use food scraps to increase the biogas production.

Reading, UK

The Bus Hound, the UK’s poo-powered bus, which set the speed record for a regular service bus with a top speed of 76.8mph (123.5km/h) back in 2015, is part of a fleet of vehicles set up by Reading Buses.

Thirty-four biomethane gas-powered Scania buses were added in 2013, and the fuel for the vehicles is produced from farm waste and injected into the national gas grid – the whole process is essentially carbon neutral.

Leeds, UK

Yorkshire Water has invested £72m in a project at its Knostrop wastewater treatment works, in which a state-of-the-art sludge treatment and anaerobic digestion facility will be built.

Four 25-metre-high concrete sludge digester tanks are already constructed. Estimated for completion in 2020, Yorkshire Water says the facility will recycle 94 per cent of Leeds’ sewage sludge, be capable of processing 131 tonnes of dry sludge a day, generate 55 per cent of its own electricity (the equivalent of providing power to 8,000 homes), and reduce the Knostrop site’s carbon emissions by 15 per cent.

Rwanda, East Africa

Sanitation company Pivot has two initiatives, Pivot Works and Pivot Fuel. Works is a city-scale treatment solution that converts human waste into renewable fuel.

According to Pivot, only 10 per cent of human waste generated in low-income countries gets treated, and traditional treatment plants are expensive, with infrastructure in many low-income cities being almost non-existent. Treating wastewater with sewer networks and aerobic treatment costs $75bn per year globally. Bad sanitation kills over two million people every year.

Pivot Works’ factories convert human waste to solid, hygienic Pivot Fuel. This is then sold to industrial customers like cement companies, and the revenue covers costs to sanitise and process the waste. According to the company, this transforms wastewater treatment from a huge cost sink into a system that pays for itself.

Kenya, East Africa

The Nakuru Water and Sanitation Services Company is manufacturing briquettes from human faeces for cooking and heating.

The waste is dried, treated in a kiln and carbonised with sawdust at 300°C. The resulting product is processed into balls and sold by the kilo. Treating the excrement removes dangerous pathogens and the smell, and will improve sanitation in poorer areas.

Nakuru is the fourth largest city in Kenya, and only one in four residents have access to the town’s sewer system – waste is often buried in lower-income areas, or dumped in rivers.

More locals are warming to the product, and it’s reported that the briquettes are odourless, burn very well for a long time, and cook food at a good speed.

Spain

In northern Spain, renovation is under way on an abandoned farmhouse to power it entirely on poo. Meghan Sapp and her start-up renewable energy company Planet Energy have designed the eco-house, which will be self-sustaining and uses waste from humans and animals to generate renewable energy.

The Netherlands

Near the end of last year, the Dutch Ministry of Economic Affairs pledged to spend €150m on a project to help the nation’s farmers to turn cow manure into energy.

The Netherlands’ agriculture industry is behind 10 per cent of the country’s greenhouse gas emissions, and methane from dairy farms is a key culprit. Farmers will be able to lease out anaerobic digesters to help reduce the emissions. The system works via a machine taking cow manure from the farm to a digester dome outside, and according to environment website Inhabitat, other machines will extract phosphates and nitrates. Farmers can use this for fertiliser and can then sell the biogas at a 12-year fixed price, which the Dutch government will subsidise.

Xiangyang, China

On an island in central China’s Xiangyang city is a steel complex processing several hundred tonnes of human waste.

Composed of human excrement and other matter, hazardous sludge – a by-product of the sewage treatment process – is becoming an increasing problem in China but, when processed, the energy produced from the factory is enough to fuel 400 cars. 

The magnitude of the toxic slurry in China is triggering the country to find more sources of clean, renewable energy, including the increase of sludge-to-energy projects. Other cities, such as Hefei, Chengdu, Changsha and Chongqing, are also experimenting with processing sludge into an energy source.

Beijing, China

Agricultural pollution is another problem plaguing China, with animal poo leaking into rivers and lakes, so farmers will now be paid to turn their livestock’s manure into fertiliser and power.

According to the Ministry of Agriculture, Chinese livestock farms produce almost four billion tonnes of waste every year.

Back in August, the Chinese government announced a plan to give farmers subsidies to build animal waste processing facilities to treat manure and make fertiliser, and to install biogas plants to generate electricity.

Reporting to Reuters, Zhong Luqing, director of the fertiliser department at the ministry, said: “We will strengthen policy support and increase subsidies to support farmers to use organic fertiliser... especially large-scale farmers, family farms and cooperatives.”

Beijing is allegedly targeting zero growth of chemical fertiliser and pesticide by 2020, urging farmers to use fewer chemicals and switch to animal manure instead. At the moment, China uses about a third of the world’s fertilisers.

Australia

Almost 40 per cent of households in Australia own at least one dog, and the 4.2 million canines will generate 6.3 million tonnes of poo in their lifetimes.

According to the Melbourne project Poo Power!, as the dog population in Australia grows, so will the issue of dog waste disposal in their communities, which are faced with increasing population growth and urbanisation, a limited amount of suitable park spaces and shrinking landfill sites.

Poo Power! wants to tap into the 1,400 tonnes of dog poo discarded daily – the company designed a biogas generator to showcase how the energy produced from dog poo and other organic wastes can be used to provide power to light dog parks in the early morning and evening peak periods.