Poo power: Human waste could heat 138 million households

Safely obtained biogas from human waste could generate electricity to power all of the households in in Indonesia, Brazil, and Ethiopia combined, if researchers can harness the correct innovative technologies.

That’s according to a new report from UN University’s Canadian-based Institute for Water, Environment and Health, which estimates that biogas extracted from worldwide human waste could have a value of up to $9.5bn as a natural gas equivalent.

The Valuing Human Waste as an Energy Resource report states: “Rather than treating our waste as a major liability, with proper controls in place we can use it in several circumstances to build innovative and sustained financing for development while protecting health and improving our environment in the process.”

The report notes that dried fecal matter – which releases biogas that is approximately 60% methane by volume when broken down in an anaerobic system – has energy content similar to coal and charcoal and could replace up to two million tonnes of charcoal-equivalent fuel, severely limiting the destruction of trees.

Fecal farce

Taking India as an example – where UN figures state that 60% currently defecate ‘in the open’ – the report suggests that if open defecation was targeted, economic generations could reach between $220m – $376m each year.

This untreated waste could generate enough electricity to power 18 million Indian households. While processing the residual faecal sludge could yield up to 8.5 million tonnes of charcoal equivalent to power industrial furnaces.

The UK has been using biogas a fuel source from as early as 1895, where street lamps were fuelled by waste in Exeter. However, the mainstreaming of AD didn’t take off until the 1990s.

Currently, there are 157 sewage, gas and water treatment work sites with AD plants in the UK. They treat about 75% of UK sewage and produce electricity and biomethane, with an equivalent electrical capacity of 196 MWe.

New technologies

ADBA’s chief executive, Charlotte Morton said: “The UN report is absolutely right to say that human waste is not a liability, but an extremely valuable resource that can be treated through anaerobic digestion to power homes, support sustainable farming and reduce carbon emissions. 

“The nutrient-rich residue, known as digestate, is broken down and stabilised by the process to become ideal substitute for expensive, carbon intensive fertiliser – it can improve soil quality and help secure food production.   

“In the UK the sewage industry has driven improvements in innovation and operational efficiency at their AD sites, resulting in a 40% increase in electrical generation from existing sites since 2009. Getting the most out of AD means investing both in optimising existing technology and new R&D opportunities. The carbon and economic case for doing so is clear.”

Flushed away

The concept of using human waste for the greater good received backing from Microsoft finder Bill Gates earlier this year. A visit to view an ‘Omni-Processor‘ saw Gates drink water procured from human waste, which he described as a ‘delicious’ and affordable way to improve sanitation.

Late last year, edie reported that the UK’s first bus powered by human and food waste had made its debut journey in Bristol. The Bio-Bus is capable of travelling up to 300km on gas generated through the treatment of sewage and food waste.

But with more than 20,000 tonnes of human excrement produced in the UK every day, there is certainly potential for more biowaste innovations. 

Matt Mace

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