The Production and Delivery of Green Hydrogen and Recovered Waste Heat

A Techno-Economic Analysis of a Multi-MW Alkaline and PEM Electrolysis Plant

More Info
expand_more

Abstract

In this thesis, both a 10 MW Alkaline Electrolyser (AE) and a 10 MW Proton-Exchange Membrane (PEM) electrolyser system are evaluated through a comprehensive techno-economic feasibility study, spanning a 25-year operational lifespan. The systems are designed to serve a dual function, producing green hydrogen at 350 bar for utilisation at a hydrogen refuelling station for heavy-duty trucks, as well as recovering waste heat via a tie-in on the cooling system of the electrolyser to directly supply a medium-temperature district heating network at 70 °C. The latter is achieved by connecting the tie-in to a heat exchanger, resulting in a cost-effective heat recovery without the implementation of an expensive heat pump. Both electrolysis systems are operated at 80 °C and powered by offshore wind power, delivered to the electrolyser system through a virtual PPA.

ERA5 data on the wind speed was employed, which was converted into power data via the wind farm power curve. The wind farm power curve was produced by coupling wind farm power production data to the ERA5 wind speed. This method proved to be effective in simulating the power production of a wind farm, as it included the wind farm wake effects and the global-blockage effect.

The performance of the AE system was simulated through a semi-empirical model for both the polarization and Faraday efficiency curve, while the performance of the PEM electrolyser system was simulated by an empirical approach for the polarization curve and a semi-empirical model for the Faraday efficiency curve. A degradation efficiency method is proposed, which employs a constant degradation factor to describe the decreasing performance over the lifetime of the stack. The degradation efficiency effectively illustrated the heat-producing degradation in electrolyser cells.
The techno-economic aspect of the research involved a detailed analysis of the Levelised Costs of Hydrogen and Heat (LCoH2 and LCoHeat). The LCoH2 of green hydrogen from the AE system was 6.08 euro/kg, while the LCoHeat of the recovered waste heat was 1.57 euro/MWh. For the PEM electrolyser system, the LCoH2 was determined to be 5.59 euro/kg, while the associated LCoHeat for the recovered waste heat was 1.55 euro/MWh. The profits of selling the recovered waste can be utilised to decrease the LCoH2. When a recovered waste heat-selling price of 50 euro/MWh was assumed, the LCoH2 of the AE and PEM electrolyser system decreased by 0.64 euro/kg and 0.44 euro/kg, respectively.

The sensitivity analysis on the LCoH2 indicated that the PPA price was the most influential factor on the LCoH2, followed by the Capital Expenditures (CAPEX) of the electrolyser system, and the start-of-life stack efficiency. When assessing the LCoHeat, the sensitivity analysis revealed that the most impacting parameters on the LCoHeat were the capacity of the installed electrolysis plant, the discount rate and the CAPEX of the heat exchanger.