Comparing the financial, energy and time costs of different food and stove combinations in Nairobi using controlled cooking tests and longitudinal fuel price data.

With a wide range of stoves and appliances available in the ever-evolving Kenyan cooking market, it is important to understand which options are the most cost, time and energy efficient to use. This information can help households to make more informed decisions about their energy use and policy makers to better understand which solutions to promote. Despite its importance, the existing literature offers scant evidence to guide optimal stove and fuel choices. In this research, we utilised controlled cooking tests to investigate the fuel required to cook six regularly prepared dishes on 10 prevalent stove and fuel combinations (including liquified petroleum gas, ethanol, charcoal, kerosene and electric appliances). We also tested the efficiency improvements from pre-soaking beans and using stovetop pressure cookers. We collected primary fuel cost data from across Nairobi in June 2023 and collated historical fuel prices from secondary sources spanning 2019-2023. The prices of liquified petroleum gas, charcoal and kerosene varied considerably by variables such as brand and location, whereas ethanol and on-grid electricity were more stable. The electric pressure cooker was the most cost- and energy-efficient device. For liquified petroleum gas and charcoal, combining pre-soaking beans with a pressure cooker substantially reduced fuel consumption, but was still costlier than the electric pressure cooker. The longitudinal comparison highlighted the dynamic nature of fuel prices in Kenya and how a household's cost-optimal cooking stack can change at short notice. These findings demonstrate how comparative affordability varies both temporally and spatially and can be heavily affected by wider market and policy incentives.