The trouble with toilets in the developing world is not that there are so few. It's that they fill up, and when they do, most local governments lack the money, the technology, and the incentive to properly manage the waste. Instead, it gets dumped, untreated, into the nearest waterway, leaving the estimated 2.6 billion people in the world who lack access to basic sanitation susceptible to all manner of bacteria, disease, and parasites.

"Building a toilet as a standalone intervention is like putting a Band-Aid on a gushing wound," says Ashley Murray. "Maybe it buys time to get to the hospital, but it's not the solution to the problem."

Murray is the founder of Waste Enterprisers, an Accra, Ghana-based start-up that plans to turn raw human waste, or fecal sludge, into biofuel pellets, a commodity that sells for $200 a ton in some parts of Europe. The for-profit company operates on the premise that human waste is the one truly infinite resource. Find a way to reuse and monetize that resource, and we may be able to stem the global sanitation crisis where it starts.

"The biggest bottleneck in sanitation is the financial model," Murray says. "The money is never around to cover the cost of waste-treatment facilities. I thought, If we're really going to make progress, we have to find a way to integrate a financial incentive to keep these systems going."

Murray has spent more than a decade studying sanitation and has a Ph.D. from the University of California, Berkeley's Energy and Resources Group. She knew that some developed countries were already finding ways to turn sewage sludge, a byproduct of wastewater treatment, into fuel. The same wasn't being done with raw human waste.

"I thought, If we can turn sewage sludge into fuel, why isn't anyone thinking of doing this with the contents of pit latrines and septic tanks?" Murray says. "It seemed so obvious."

In 2009, Murray took a job in Ghana with the International Water Management Institute. A year later, she founded Waste Enterprisers, which now has six employees.

Instead of dumping waste at the beach, as is customary in Accra, cesspit trucks that work with Waste Enterprisers will deliver the waste to the company's factories. There, it will be dried, treated, and transformed into solid fuel pellets. The treatment process, which is compliant with EPA standards, removes pathogens using heat, desiccation, and UV rays, making the fuel completely safe to handle and burn. That fuel can then be sold to power plants and other heavy users of fuel. Initially, Waste Enterprisers will sell the product in Europe, where demand is high thanks to the European Union's plan to derive 20 percent of its energy from renewable resources by 2020. Once Waste Enterprisers expands, Murray hopes to sell locally, too.

Murray says the first small-scale factory in Accra will be operating by January, generating 5 tons of fuel daily, which requires 95 tons of raw sewage to produce. That's a small fraction of the 2,000 tons of the stuff the Accra Metropolitan Assembly says is being collected every day. That's why, within a year, Murray plans to open a full-scale factory that will produce 70 tons of fuel a day. That factory will provide waste-management services to about one million people.

That kind of potential hasn't gone unnoticed by financiers. Since it launched, Waste Enterprisers has landed a $1.5 million grant from the Gates Foundation. It received another $78,000 from the European Union. Meanwhile, Murray has been accepted into the Unreasonable Institute, an accelerator for entrepreneurs whose ideas could improve the lives of at least a million people. After meeting with investors there, Murray secured $240,000 of the $300,000 round of funding she's seeking.

"We all think what Ashley's doing is a true revolution, and if she can get it to work in Ghana, she can probably bring it anywhere," says Teju Ravilochan, Unreasonable's CEO. "If this really takes off, it could reach hundreds of millions, maybe even billions, of people."

Murray says Waste Enterprisers will probably expand to Kenya, Uganda, and Senegal next, and that other promising markets, including India, won't be far behind.

"This is a huge environmental crisis," Murray says. "Feeling like I can play a role in mitigating the impact of poor sanitation is really motivating and compelling. We want to roll this out across the continent of Africa, revolutionize sanitation there, and perhaps, beyond."