Electricity generation from a biomass cookstove with MPPT power management and passive liquid cooling

An electrical power generator for use with biomass cooking stoves has been developed. The design is intended for users in developing countries who lack regular access to electricity. Electricity is generated based on the thermoelectric effect. A bespoke heat collector captures heat from the combustion chamber of the cooking stove and transfers it to a single thermoelectric generator (TEG) module. To maintain a sufficiently high temperature difference across the TEG, heat is dissipated using a passive single phase liquid thermosiphon system. This cooling system eliminates the requirement for mechanical components such as fans or pumps, which are unreliable and draw significant electrical power. In a controlled laboratory setting, a maximum power of 5.8 W has been produced from a single TEG installed into a low cost ceramic cooking stove currently disseminated in large numbers in Malawi, Africa. The TEG power is controlled using a maximum power point tracking (MPPT) conditioning circuit with an estimated efficiency of ~70%. The circuit provides a stable 5 V output via a USB connector for charging mobile phones, lights, power banks and other devices. Experiments have shown that the device is capable of performing for extended periods without significant reduction in performance. The magnitude of the power generated by this passive cooling system is observed to be comparable to that delivered by similar TEG-stove systems driven by active cooling. An average power generation of over 4 W was achieved which, including circuit efficiency, provided ~10 W·h of useful electrical energy over a 4 h burning interval, which is sufficient for charging low powered electrical appliances. Five prototypes fitted with data measurement and acquisition were deployed to families in rural Malawi in order to evaluate real-life performance of the technology. Initial field-trial results have advocated the viability of the TEG-stove technology for charging low powered electronic devices typically used in developing countries such as Malawi.