Thermo-ecological cost – System evaluation of energy-ecological efficiency of hydrogen production from renewable and non-renewable energy resources

Abstract

Hydrogen is expected to be a key fuel in the global energy transition. It is characterised by diverse potential applications in the industrial, transport, energy and building sectors. An increase of hydrogen production from renewable energy (RES) is especially important from the point of view of further sustainable development. However, a dominant share of hydrogen production is still covered by steam methane reforming (SMR). In order to facilitate the increase of the share of H2 from RES, efficiency of various hydrogen production technologies should be properly assessed. Majority of scientific publications consider only the local energy efficiency of the hydrogen production methods. From this perspective the production of hydrogen by SMR is characterised by higher efficiency than production of hydrogen from RES. In order to properly evaluate the global efficiency of hydrogen production technologies, we propose an advanced system exergy analysis – Thermo-Ecological Cost (TEC). Additionally, we propose to consider the production of hydrogen via electrolysis as cogeneration of two useful products - hydrogen and oxygen. Such approach allows to decompose the energy expenditure for the process and assign a lower burden for the main product (hydrogen). The results of TEC analysis for hydrogen production from non-renewable and renewable resources are presented and compared with the local energy efficiency of these technologies. The presented results confirm the thesis that local energy efficiency is not a proper tool for evaluation of effectiveness of hydrogen technologies, especially when production of hydrogen from non-renewable and renewable energy is to be compared.