Optimisation of Electrolyser Operation: Integrating External Heat

Integrating external heat into electrolysers can reduce the electrical power demand for carbon-neutral hydrogen production. Efficient operation requires detailed models that incorporate heat availability and its effect on startup costs. This paper advances existing operational models by endogenously modelling startup costs and direct heat integration, based on a piecewise linear approximation of the electrochemical equations. We analyse the impact of low- and high-temperature heat integration on the efficiency and profitability of hydrogen production for solid oxide and proton exchange membrane (PEM) electrolysis technologies. Our case study demonstrates that heat integration can significantly enhance the profitability of solid oxide electrolysis, increasing average daily profits by up to $\mathbf{2 3. 3 \%}$. For PEM electrolysis, the impact is more modest, with profit gains of $1.9-2.7 \%$. Despite this, the break-even hydrogen price for solid oxide electrolysis remains high at 5.5 EUR/kg, given an investment cost of 2300 EUR/kW. PEM electrolysis achieves breakeven at more competitive hydrogen prices of 3.5-4.5 EUR/kg, depending on lifetime assumptions and an investment cost of 900 EUR/kW.