Kristian Lyngvig Kvist
Master Thesis - Energy Technology - 2019
A paradigm shift is right now happening all over the globe, fossil fuels are being replaced with renewable energy. There are great differences in how far each country and each energy demanding sector is in this transition. In general, the transport sector is lacking behind other sectors. This is primarily because the transport sector needs high density fuels and can only use electricity for some demands. which is why hydrogen is perfect for the transport sector as it can be produced by renewable electricity and used for almost all demands in the transport sector.
The thesis creates a system consisting of a large central electrolyser that supplies hydrogen to an oil refinery and to multiple hydrogen refuelling stations for buses and taxis. The hydrogen for buses and taxis is transported with high-pressure trailers from the central electrolyser to the hydrogen refuelling stations (see system visualisation below).
Further the thesis optimises the operational strategy for a large 20MW electrolyser based on hourly electricity prices. The thesis finds that up to 33% of the electricity cost can be saved, if operating the electrolyser based on this operational strategy compared to producing hydrogen at a constant volume.
With inputs from the operational strategy seven different scenarios are created. These scenarios consist of hydrogen production in Fredericia close to an oil refinery, which will consume 1,000kg hydrogen per day. Further are different amount of hydrogen refuelling stations, each for 50 fuel cell taxis or fuel cell buses included in the scenarios. There is a large difference in the cost of supplying hydrogen for the different demands and the different scenarios. It is cheapest to supply hydrogen for the refinery, then for the bus hydrogen refuelling stations and lastly for the taxi hydrogen refuelling stations. In the best scenario it will cost 5EUR/kg hydrogen supplied for the refinery and in the same scenario it will cost 11EUR/kg hydrogen to supply hydrogen for a taxi refuelling station in Copenhagen.
The electrolyser produces high amounts of heat, and if a large hydrogen factory consisting of 400MW electrolysis is placed at the district heating network in Fredericia it will alter the heat production in the net significantly. If a 20MW electrolyser is placed instead it will supply 57TJ heat per year, which the district heating net can handle without changing other production units.
Collaborating Partners
Nel Hydrogen