Cleaning up the stack: Evaluating a clean cooking fuel stacking intervention in urban Kenya

There are a growing number of market-based providers of clean cooking solutions in sub-Saharan Africa that rely on use customer fuel sales to subsidise upfront cost of equipment. These business models can widen access to clean cooking but are undermined by the continued use of polluting fuels, known as "fuel stacking", which limits provider revenues whilst perpetuating the negative impacts of cooking with traditional fuels. This study aimed to design and test a fuel stacking intervention with commercial pay-as-you-go LPG customers in Kisumu, Kenya. It consisted of three main phases: developing and testing a survey tool for diagnosing drivers of stacking (n = 99); using an intervention design framework (the Behaviour Change Wheel) to design an intervention consisting of the bundled provision of a pressure cooker, chapati pan and training; and testing the intervention in a small (n = 19) pre-post study. There was high uptake of the intervention, with the pans being used by all participants on roughly two-fifths of days. Target foods were cooked more frequently on LPG in the intervention phase, resulting in a significant increase in PAYG LPG use and an insignificant decrease in charcoal use. A third of participants stopped cooking with charcoal altogether, but some residual charcoal usage continued amongst the remainder. The results show that targeted stacking interventions can simultaneously promote sustained use of clean fuels and dis-adoption of polluting ones, resulting in commercial gains for clean cooking fuel providers. This could address the wicked problem of fuel stacking and accelerate progress towards Sustainable Development Goal 7.