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A group of researchers just put a price-tag on poop: extracting biogas from the world's annual human waste output could be worth the equivalent of up to $9.5 billion in natural gas, according to a report released Tuesday by the United Nations University Institute for Water, Environment and Health.

Which means we could all be sitting on gold mines.

"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," co-author Chris Metcalfe of Trent University said in a release. "Challenges are many but clearly there is a compelling, multi-dimensional financial case to be made for deriving energy from waste."

[You can earn $13,000 a year selling your poop]

Such fuel can come in the form of methane-rich biogas, generated by the bacterial breakdown of feces in an oxygen-free environment. The residue could then be dried and charred into sludge, an energy source akin to coal or charcoal, the authors write.

The report authors calculated the low and high assumptions for how much biogas and sludge can be made from the average amount of waste humans produce, and then the monetary value of the fuel sources' energy equivalents. The result: turning people's poo into fuel could be worth between $1.6 billion to $9.5 billion. The higher figure equals roughly the fuel needed to power households in Indonesia, Brazil and Ethiopia.

[Your poop could be a literal goldmine of precious metals]

Harnessing fuel just from people who defecate in the open could be worth $200 million, the authors estimate.

But it's not so clear-cut; the authors write there are concerns about the safety of such fuels, and that testing is needed to show they don't "impact food taste or quality." And the process of production could initially be costly.

Oh, and then there's this, from the report: "Clearly 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."

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