Economic and environmental analysis of hydrogen production when complementing renewable energy generation with grid electricity

Abstract

Hydrogen (H2) can be a critical factor in achieving a more sustainable society reducing carbon emissions worldwide in the long run. However, there are some challenges to be solved yet. One of these challenges is that, right now, the economical competitiveness of electrolysis production strongly depends on the Renewable Energy Sources (RES) availability. This paper analyzes the economic and environmental implications of complementing the power supply of a H2 production plant that usually operates using only RES with grid electricity during the time RES are not available. For performing this analysis, we proposed an assessment model that incorporates Alkaline (ALK) and PEM electrolyzer technology features (such as the low dynamic load range of ALK electrolyzers, which is usually ignored when modeling H2 production). Moreover, we introduce a new metric, named the LCOH&E, which captures the existing trade-off between reducing the Levelized Cost Of Hydrogen (LCOH) with more H2 production using grid electricity and increasing CO2 emissions by producing more H2 with grid electricity. We illustrate the proposed assessment model with a case study based on real data from Chile. Our results show that the optimal fraction of grid electricity to be used in producing H2 may be different when minimizing the LCOH and when minimizing the LCOH&E because of the LCOH-CO2 emissions’ trade off. Moreover, it is remarkable that using only 10% of grid electricity in an ALK electrolyzer, it is possible to increase the H2 production in 25.7%, without significantly increasing the CO2 emission level.