Hydrogen Production in a Future Low-emission Energy System: A Case Study of Denmark

Abstract

Reducing global carbon emissions is becoming increasingly important to combat global warming, and hydrogen is being recognized as playing a key role in the decarbonization of energy systems. This thesis performs a case study of the Danish electricity system to investigate what investments can make it compliant with the Danish climate targets and fulfill future hydrogen demand. It presents the development of an electricity dispatch model with capacity expansion, which aims to analyze the electricity system for the years 2030, 2040, and 2050 with grid-connected electrolysis for hydrogen production. The model seeks to find the optimal capacity for renewable energy sources (RES), batteries, and electrolyzers to fulfill long-term electricity and hydrogen demand while reducing carbon emissions. The model assumes a 95% emission reduction by 2050 as going to 100% is very costly. A brownfield approach is used, and Denmark is modeled as two zones, DKE and DKW. Furthermore, extensions of the model examine the optimal infrastructure expansion between the Danish zones and the effect of electricity import from neighboring countries. We found that the Danish energy system needs electrolyzer capacities of 3.4, 5.5, and 6.6 GW to fulfill the estimated domestic hydrogen demand for 2030, 2040, and 2050, respectively. To lower carbon emissions and support the production of green hydrogen Denmark needs to increase the capacities of RES significantly. In 2050, the optimal mix of RES are found to be 33, 17, and 12 GW of solar panels, offshore wind, and onshore wind, respectively. The increase in RES leads to an increased need for energy storage in the form of large battery capacity to complement the intermittent power supply. Taking import from neighboring countries into account reduces the need for large battery capacity but will decrease Denmark’s energy autonomy. It is found that especially the last percentage of carbon emission reduction is twice as expensive as a 99% reduction. It will likely require the usage of other technologies than those included in this study to reach a 100% reduction in a cost-efficient way. This could be some form of dispatchable energy source combined with carbon capture technology which could also provide CO2 for the PtX sector.