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 recently 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. “Challenges are many but clearly there is a compelling, multidimensional financial case to be made for deriving energy from waste.”

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.

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