This innovative new cookstove attachment solves two problems for off-grid homes: It turns the stove into a power generator and it improves kitchen air quality at the same. The attachment is a thermoacoustic generator based on a technology that NASA has tested for propelling space probes, but built with cheap parts, including an off-the-shelf loudspeaker. The makeshift attachment uses waste heat from the stove to make a soundwave inside a resonator, which it then runs through a loudspeaker working in reverse to convert the sound into electricity. It’s a prototype now, but the goal is to make a model that generates 10W and costs about $25. The stove is designed to work with most biomass-burning cookstoves, and part of the electricity that it generates powers an internal fan that blows smoke back over the flames to consume most of the pollutants.