Close to 1 billion people defecate in the open, and around 2.4 billion don’t have access to proper sanitation, according to the United Nations Children’s Fund and the World Health Organization.
“When it comes to creating misery and poverty, human waste management has few rivals,” said Zafar Adeel, the director of the United Nations Univ.’s Institute for Water, Environment and Health (UNU-INWEH). “If we can demonstrate a simple, cost-effective new approach in low-resource settings, if we can successfully make a business case and change the economic paradigm of human waste management, we can advance development, protect the environment and help reduce sanitation problems causing one-tenth of all world illness.”
Rather than viewing untreated human waste negatively, a new report from the UNU-INWEH suggests utilizing biogas and the leftover slurry from human waste as potential energy sources.
“If only those individuals in the population practicing open defecation were targeted, the minimum estimated value of biogas is more than $200 million/yr—enough to meet the annual electricity demand of almost 10 million local households,” the report reads.
Further, the dried and charred residue could produce between 4.8 and 8.5 million metric tons of charcoal-equivalent fuel.
Extended to all the world’s human waste, the monetary value ranges between $1.6 billion and $9.5 billion, the latter value covering the electricity demands of over 138 million households.
“Cleary there is a financial incentive in generating energy by-products from waste, but this may not be sufficient in all cultures to overcome the ‘ick’ factor of using our own waste. Concerns exist regarding the safety of fuels derived in this way, particularly for the solid fuel,” the report reads. “Testing is required, linked to marketing demonstrations to introduce these different fuels.”
Approximately 60% methane by volume, biogas is generated through bacterial breakdown in fecal matter in an oxygen-free environment. Urine plus feces, referred to as “black water,” has a general nutrient value of 4,550 g of nitrogen and 548 g of phosphorous per human, per year.
“We recycle the nutrients in human waste effectively via agriculture in many places, yet the potential energy value of human waste has been given much less attention to date,” said report co-author Chris Metcalfe, of Trent Univ. “Challenges are many but clearly there is a compelling, multi-dimensional financial case to be made for deriving energy form waste.”
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