Pay-as-you-cook: The biogas idea fuelling trade in Kisumu

At the bustling shoreline of Dunga Beach in Kisumu, where fishermen haul in their daily catch and traders sort through piles of omena, a quiet transformation is underway. What was once a site grappling with waste, smoke-filled kitchens and the choking spread of water hyacinth is now a model of clean energy innovation, thanks to the work of Dominic Wanjihia Kahumbu.

 Kahumbu, the founder of Flexi Biogas Solutions, has pioneered a community kitchen project that is redefining how local communities cook, earn, and interact with their environment. Based in Karen, Nairobi, his biogas venture specializes in biogas systems that convert biodegradable waste into usable energy. But it is at Dunga Beach that his innovation finds its most compelling expression. 

“This project is about turning a problem into an opportunity,” Kahumbu says, adding “We are taking waste that would otherwise pollute the environment and converting it into clean, affordable energy for the community.”

 The Dunga Beach project is more than just a kitchen. It is a fully integrated, community-scale system that powers a communal cooking space, fish drying units, poultry brooders, and small businesses around the beach. At its core lies a simple but powerful idea: waste is not useless; it is fuel.

 Every day, organic waste is collected from multiple sources around the beach. Fish remains from cleaning stations, food scraps from nearby eateries, market waste, and large quantities of water hyacinth; an invasive weed choking Lake Victoria; are gathered and sorted. According to project estimates, up to 150–200 kilograms of water hyacinth can be harvested daily.

Not all of this waste ends up in the system. About 45 percent is fed into the biogas digester, while the rest is either recycled or used directly as compost. The selected organic material is chopped, mixed with water, and fed into a flexible, airtight digester; a large, durable plastic tank that creates an oxygen-free environment.

 Inside this chamber, microorganisms break down the waste through anaerobic digestion, producing biogas; a mixture primarily composed of methane and carbon dioxide. The process mirrors natural digestion systems found in animals. The resulting gas is then captured, stored, and piped directly to the community kitchen.

 The impact is immediate and visible. Instead of cooking over smoky charcoal stoves, users now access clean-burning biogas. The kitchen operates on a pay-as-you-cook model, allowing customers to purchase cooking time or gas credit through small token payments; often made via mobile money platforms like M-Pesa.

 A fish trader arrives with her produce, pays a small fee, and is assigned a cooking station. Within minutes, she is preparing her food over a steady blue flame; free from soot, smoke, or the unpredictability of firewood. When her allocated time runs out, she can top up and continue cooking. 

“It works just like buying airtime; you pay for what you use, and it’s much cheaper and cleaner than traditional fuels,” Kahumbu told City Biz.

 Organic waste 

This model has proven both practical and profitable. The project generates income through multiple streams. Token payments from kitchen users form the primary source of revenue, but the system goes further. Businesses and households that supply organic waste either pay small disposal fees or benefit from discounted energy, effectively turning waste into a tradable commodity.

 Additionally, the by-product of the digestion process; bio-slurry; is sold as organic fertilizer to farmers, creating another income stream. Value-added services such as fish drying, poultry brooding, and support for small enterprises further strengthen the project’s financial sustainability.

 Beyond the economics, the environmental benefits are significant. By reducing reliance on firewood and charcoal, the project helps curb deforestation. The removal of water hyacinth contributes to the restoration of Lake Victoria’s ecosystem, while improved waste management reduces pollution along the shoreline.

 Socially, the project is equally transformative. Women and small-scale traders; who form the majority of kitchen users; benefit from faster cooking times, cleaner working conditions, and reduced fuel costs. The absence of smoke improves health outcomes, particularly for those who previously cooked in poorly ventilated spaces.

 What sets the Dunga Beach initiative apart is its integrated, community-driven approach. Unlike household biogas systems, this model serves multiple users and functions simultaneously, linking energy production with environmental conservation and local enterprise.

 For Kahumbu, the success of the project lies in its scalability.

 “If we can do this in Dunga, we can replicate it in other parts of the country,” he says. “The idea is to empower communities to manage their own waste, produce their own energy, and create their own economic opportunities.”