Global Waters
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Global Waters

Trying to Solve Sanitation and Energy Problems at the Same Time

Waste is collected from Sanergy Fresh Life Toilets daily and taken to a central processing facility. The use of wheelbarrows and handcarts ensures that toilets deep in informal settlements, where there are only narrow, unpaved roads, can still be reached. Photo credit: Sanergy

Urban areas in the developing world face many challenges because of booming population growth. Infrastructure is often inadequate, resulting in such problems as the spread of disease from poor sanitation, and the loss of surrounding forests due to high demand for affordable cooking fuel.

The problems are daunting. In Kenya, for example, 95 percent of fecal sludge is disposed of in the environment, whether in pit latrines that are never drained, piped directly into rivers or lakes, or out in the open. An estimated $324 million is lost annually to Kenya’s economy from the health issues that result. Meanwhile, the country is losing 12,000 hectares of forest each year, in part due to the demand for cooking fuel. Could these two problems be solved at the same time?

Through innovation grants and tailored acceleration support (ranging from regulatory and legal assistance to business development and human resource support, among other areas), USAID works with a number of projects that are exploring models for turning human waste into usable energy. Mostly located in East Africa, these projects convert liquid and solid waste into either biogas or solid fuel briquettes that can be used for home cooking.

The USAID grantees take different approaches to waste-to-energy solutions, such as where and how the waste is collected. For Green Heat in Uganda, Zanmi Lasante Biogas in Haiti, and Sanivation in Kenya, the collection point is in the home using specially designed toilets. In Kenya’s Sanergy project, the collection point is a centrally located “Fresh Life” toilet either in public areas or in a residential compound, which is run by a franchisee. Customers pay a weekly or monthly subscription or a per-use fee to access the clean and fully equipped toilet. Sanivation’s customers also pay a per month subscription of $2; the toilet itself remains the property of Sanivation even though the customer houses it.

Briquettes made from processed human waste dry before being sold as cooking fuel. These briquettes have lower carbon monoxide emissions than traditional charcoal, no smoke, and burn twice as long. Photo credit: Sanivation

Each innovator has developed its own process for converting the waste into a resource. Zanmi Lasante and Green Heat both install sealed, oxygen-free digester systems in the homes of their customers. The microorganisms in these anaerobic systems break down the organic matter and convert it into fertilizer and biogas, which can be used as a cooking fuel. Zanmi Lasante is exploring pay-for-use digesters, charging a small fee for the use of flush toilets and selling both the resulting fertilizer and biogas. Green Heat has developed a system that cuts water use by 85 percent, enabling even families without reliable water access to use them. This system uses a solar-powered sewage pump and heating process to “digest” and dewater latrine slurry and convert it into solid fertilizer that can be packaged, stored, or applied directly to fields. During this digestion process, biogas is also released, which is captured in tanks and can be piped into kitchen cookstoves, eliminating the toxic smoke of wood cooking fires. In the case of Sanergy, which received USAID funding from 2011 to 2015, waste cartridges are collected from each of the Fresh Life toilets daily and brought back to a central processing facility outside Nairobi, where they are converted into fertilizer, animal feed and biogas and then sold.

Sanivation takes yet another approach. Team members collect waste from each home toilet twice a week and treat it through a solar thermal process. The sanitized sludge is then mixed with a carbonized waste, such as charcoal dust or plant waste from nearby plantations, to form briquettes that can be burned as cooking fuel. These briquettes have lower carbon monoxide emissions than traditional charcoal and they produce no smoke, protecting the lungs of those in the kitchen. The whole process from collection to finished briquette takes as little as four days. So far, Sanivation has sold 120 metric tons of briquettes, simply from waste from 120 households in the town of Naivasha.

Briquettes are available for sale in Nairobi-area grocery stores. For every ton of briquettes sold, 88 trees are saved. Photo credit: Sanivation

“It’s not a one-size-fits-all for sanitation,” explains Kate Bohnert, Sanivation’s business development lead. “We’re trying to understand what the community needs and what kind of fuel we can make in the community.” USAID began its support of the project in 2017 and is projected to continue its funding through 2020.

All of these projects have started small but hope to scale up. Sanergy is working toward providing sanitation services to 100,000 residents of Nairobi’s informal settlements through a network of 1,000 franchised toilets. Sanivation’s goal is to reach 1 million people in East Africa’s cities and refugee camps by 2020.

Members of the community are keenly interested in the opening of new, hygienic toilets in their neighborhood. Photo credit: Sanergy

All of these projects, however, need to overcome considerable challenges to scale and become sustainable. At this point, none of the innovators are generating enough revenue to continue operations without donor or investor support. And, without massive investment or significant shifts in their operational or business models, this may continue to be the case. For example, Sanergy needs a much larger production facility to produce the volumes of animal feed and fertilizer they need in order to reach profitability. In 2017, Sanergy successfully attracted that capital through impact investment funds and development finance institutions. The projects that seem best placed to succeed are those that focus on meeting household needs with products directly from the household itself, such as Green Heat’s model. Projects relying on central processing facilities and resale can often run into barriers to scale.

Jesse Shapiro, USAID environmental health team lead, senior WASH advisor, and sanitation focal point, explains that by funding all these waste-to-energy projects, USAID is exploring possible options for addressing sanitation problems in developing countries. “It makes a lot of practical engineering sense to try to make use of waste products,” he says. “Most of our investments in this area are through DIV [Development Innovation Ventures], and the purpose of DIV is to invest in big ideas, more innovative ideas.” But, he adds, “To make this work, most of the innovations will need to operate within a business environment where they make a profit or receive support from local government.”

Subsurface biodigesters convert human waste into biofuel and dry fertilizer. They offer long-term sanitation solutions for schools and other rural institutions. Photo credit: Green Heat

Although a win-win solution in concept may not be an immediately viable business proposition or solution ready for scale, promoting innovation and providing tailored nonfinancial support are important steps in cultivating solutions to the daunting and growing problems of sanitation access, waste disposal, and energy use. By funding and testing different models of waste-to-energy conversion, USAID is learning what is feasible and sustainable, which will help guide future programming in the years to come.

By Christine Chumbler

This article appears in Global Waters, Vol. 9, Issue 3; for past issues of the magazine, visit Global Waters’ homepage on



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USAID Water Team

USAID Water Team


USAID and its partners improve access to clean water and safe sanitation to create a healthier and more #WaterSecureWorld. For more, visit