As global population and human development continues to balloon, the world will be faced with a convergence of major infrastructural problems. Perhaps most notably: energy demand is expected to rise precipitously, and our waste management infrastructure will be put under increased strain.

So why not kill both birds with one stone?

That’s the idea behind poop power. Yes, get your giggles out now: I said ‘poop power’. The idea is to transform our dirty, smelly excrement, into clean, occasionally-also-smelly (but sustainable) energy.

Though it may elicit laughs, the potential of poop-to-power technology is actually serious business. Not only does the technology have the ability to supplement our energy needs, but by using human waste as an input, it also does away with a major pollutant. Really, it’s the quintessential model of sustainability.

A number of companies, cities and countries are already seeing sewage as a power source rather than as a waste problem. Here are 8 major ways that power is being generated from poop:

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City Sewage

Perhaps the most clearcut way to transform your poop into power is to convert it into biogas via anaerobic digestion. Basically, when sewage is fed to anaerobic bacteria, they eat it up and belch out a waste product of their own: biogas. This can then be funneled directly into the already-existing natural gas distribution system, transformed into electricity, or burned off immediately for energy.

A number of North American cities have already installed biogas digesters into their waste treatment facilities. For example, the Lions Gate Wastewater Treatment plant in Vancouver, British Columbia, has launched a biogas project designed to supplement the city’s natural gas supply.

Another city employing such an approach is Brooklyn, NY, at the Newtown Creek Wastewater Treatment Plant. The facility recently got an overhaul so fewer smells escape into nearby neighborhoods. Which is a real win for locals, but a major loss for pets who will now bear all the blame for unclaimed flatulence.

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Manure Mania

If you think human waste is a problem, just imagine the amount of waste that comes from our farm animals. Poop from the big three– cows, pigs and poultry– represents a monumental waste problem of its own. Manure has long been used as fertilizer, but there is vast untapped energy potential here too. In fact, it has been estimated that transforming cow poop to biogas could meet 3 percent of North America’s energy needs. Projects launched in California and Ontario, Canada are already ahead of the curve, to name just a few.

Pigs are another major source of poo… er, power. China is investing heavily in transforming poop from their estimated 700 million pigs into energy. Even Google is making an investment in pig plops as part of their effort to make the company carbon neutral.

And don’t forget poultry. China is on top of this one too, already with a chicken-manure biogas plant up and running near Beijing.

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Toot Engines

Poop isn’t only useful for generating electricity; it can also fuel your vehicle. Who knew that it would one day be your exhaust that was coming out of your car?

In fact, Volkswagen has debuted a version of its iconic Bug that runs on processed sewage. Its converted 2.0-liter, four-cylinder motor can generate speeds up to 114 miles per hour.

The city of Oslo, Norway, is also fueling its buses with flatulence, so to speak. Sewage from about 250,000 Oslo residents is enough to operate 80 buses for around 62,000 miles each.

Perhaps the most bizarre poop-powered vehicle, though, is this motorcycle with a built in toilet (pictured above). Or is it a toilet with a built-in motorcycle? Designed by Japanese toilet manufacturer Toto, the bike ensures that you’ll never have to stop to use the rest room, or a gas station, ever again.

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Diaper Power

Toilets are handy receptacles for capturing and pumping our poop to centralized treatment plants. But what about the waste that doesn’t make it to the toilet? No, I’m not talking about peeing in the shower. I’m talking about when your baby poops (before it was potty trained, that is).

Of course, that’s what diapers are for. But why let all of that waste to go to, ahem, waste? That’s what Canadian company AMEC-PLC was asking. So they built a facility capable of turning billions of poopy diapers into energy.

While collecting all of those diapers is still an arduous and, let’s face it– dirty, task, it certainly beats having the diapers end up in landfills.

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Prisoner Poop

Generating power to cook for around 10,000 inmates isn’t cheap for Cyangugu prison in Rwanda: they used to spend about $44,000 dollars annually just for firewood (that’s a lot of money in Rwanda). It also means a lot of trees being cut down.

That was before a 150 cubic meter biogas digester was donated by the Kigali Institute of Science and Technology’s Center for Innovations and Technology Transfer. Now poop collected from 1,500 of the prison’s inmates is being used to power the kitchens, cutting the energy bill in half.

It certainly gives a whole new meaning to the idea of a ‘gas-powered stove.’

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Pooper-Scoopers

Aside from those of you who have trained your pets to use the toilet, dogs and cats represent another fountainhead of poop that has been under-utilized as a power source. But a methane digester might be coming soon to a dog park near you.

A plan, originally imagined by artist Matthew Mazzotta, to turn dog waste into power for lamps at a dog park in Cambridge, MA, has caught the world by storm. The idea is pretty simple: instead of tossing your pets’ poops in a trashcan, you toss it into an on-site 500-gallon biogas digester. The digester then generates enough power for the park’s lamps.

Dog parks as far away as Gilbert, Arizona and Melbourne, Australia, have already begun employing their own pet-poop power stations too.

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Zoo Poo

We’ve covered human sewage, farm animal waste, dog droppings, and even baby poop. What’s left?

Zoos are another place with major poop problems, and I don’t just mean from the patrons. All of those animals generate a lot of waste, and keeping zoo facilities powered up can be expensive. Zoos therefore make perfect places for utilizing poop power.

The Munich Zoo in Germany is the first zoo in the world to take full advantage. They’ve installed three large digesters for generating biogas, which are filled up weekly with the poop from all of the park’s vegetarian animals. (The elephants make the most significant contributions). The energy generated then goes toward heating the enclosures of various warm-weather critters.

Photo Credit: Nanyang Technological University

Toilet Tech

If we’re going to take poop power seriously, then we’ll need to begin thinking differently about toilet technology too. Luckily, researchers are already on it.

Scientists at Nanyang Technological University have invented a new toilet system that not only makes the distribution of our poop more efficient, but it saves a ton on water too.

The system saves on water by working a lot like the vacuum toilets that exist in airplane lavatories. Perhaps most impressive, though, is the way it separates liquid from solid waste. Liquid waste can then be streamlined straight to a facility that specializes in creating fertilizer. Meanwhile, solid waste gets flushed to a biogas plant to be transformed into electricity or fuel.