The cost-effectiveness of clean cookstove carbon mitigation after adjusting for additionality and impact

More than 200 million people cook with charcoal daily. This has high climate costs: a Kenyan household using a charcoal stove emits as much CO 2 e per year as an average U.S. household using a gasoline vehicle. However, concerns around additionality (do subsidies increase sales?) and impact (do sales reduce emissions?) undermine the clean cooking transition. We conduct a randomized trial with 955 households in Nairobi to quantify the additionality and impact of subsidies for an improved cookstove in use by millions of households. Factoring in that 16% of total subsidy spending flows to non-additional participants, incentivizing one additional stove sale requires US$32 in subsidy spending. Three-and-a-half years later, 83% of buyers own a working improved stove and 11% of non-buyers do. Factoring in control group adoption and breakage rates, each additional stove generates at least 2.8 additional years of working improved stove ownership. Despite widespread stacking, stove ownership on average abates 1.7 tCO 2 e per year. Together, the subsidies abate CO 2 e at US$7 per ton (estimates range between US$3.5 and US$8.1). Each dollar of cookstove subsidy abates 168-383 times more CO 2 e than a dollar of electric vehicle subsidy.