Lead-acid battolysers for hydrogen cooking: A comparison with electric cooking for sub-Saharan Africa

Abstract

A battolyser combines the function of battery and electrolyser in one device, i.e. it provides both electrical energy storage and a means to produce hydrogen. A battolyser with lead-acid chemistry has recently been proposed, and this has potential as a particularly low-cost solution. Here, the battolyser is considered for the production of hydrogen as a cooking fuel (“hCooking”) in sub-Saharan Africa, a region where cooking typically employs polluting fuels (firewood and charcoal). The more conventional approach for decarbonisation of cooking is the introduction of electric cookers (e.g. hotplate, induction hob, pressure cooker) which can be powered by PV and possibly battery storage; accordingly these electric cooking (“eCooking”) systems are considered as the competing decarbonised technology. Multi-objective optimisation is used to design both battolyser and eCooking systems for a notional off-grid community, with solar PV as the main energy source. Objectives are the minimisation of net present cost and lifetime greenhouse gas emissions, and Pareto frontiers are produced to show the play-off between these. Results show that a battolyser system could eliminate 95.6 % of CO₂ emissions when compared with a baseline using charcoal, at an annualised cost of $507 per household, over a system lifetime of 20 years. However, eCooking systems appear superior to the battolyser, with the cleanest battery + eCook system achieving 95.8 % emissions reduction at annualised cost $422/household. More generally, hCooking systems are nearly always Pareto dominated by eCooking systems, even under a realistic range of sensitivity scenarios. This result is due to the inherently higher energy intensity of cooking over a flame compared to the eCooking options. Priorities to make the battolyser a more viable solution include extending its lifetime as far as possible, cheaper PV systems, and improved hydrogen burner efficiencies. We also show that eCooking together with some continued use of charcoal may be the cheapest possible cooking solution, whilst simultaneously curtailing 60 % of lifetime greenhouse gas emissions.