Optimisation of a hydrogen production - storage - re-powering system participating in electricity and transportation markets. A case study for Denmark

The power capacity of renewable energy sources is constantly increasing through the installation of new units, primarily comprising the most mature technologies such as wind and solar energy converters, as well as through the implementation of innovative technologies that are currently at an infant stage of development. The aim of this study was to investigate the prospects of implementing hydrogen technologies in the electricity network as an electricity production unit or/and utilise the produced hydrogen as transportation fuel. Three main scenarios were identified to be the most appropriate for this: (1) Support of the electrical grid via a fuel cell; (2) participation of a hydrogen production and fuel cell system in the electricity and transportation markets; and (3) participation in the transportation market. The results indicated that a fuel cell generator providing ancillary services is not economically viable in the investigated case study, while implementing a hydrogen production unit with a hydrogen fuel selling price between 4 and 114 (sic)/kgH(2), depending on the electrolyser's power input, will yield positive results. For the third scenario, the hydrogen fuel price ranged between 3.6 and 15.0 (sic)/kgH(2). This research shows that hydrogen technologies can be used in the electricity and transportation markets from a technical point of view. However, from an economic point of view, a hydrogen system used only for a single application does not seem to be financially appealing. This suggests that reducing the investment cost and/or limiting operating costs is mandatory to support this type of investment.