OFFSHORE WIND POWER CO-OPERATED GREEN HYDROGEN AND SEA-WATER OXYGENATION PLANT: A FEASIBILITY CASE STUDY FOR SWEDEN

Sammanfattning: The world energy production, transformation, storage, and usage are under a dramatic change. Actions are being taken by Governments to slow down the effects of the climate change. Wind energy is expected to be a central pillar for this change. However, a key issue facing the expansion of wind energy, especially in Sweden, is the integration of the massive amounts of new generation into the electricity grid (Energinet et al., 2021; Ingeberg, 2019; IVA, 2020). Another challenge facing the expansion of the wind energy is that it can’t be used by end-sector which rely on energy-dens carriers (IRENA, 2020b). In the pursuit of solutions to these challenges, green hydrogen produced by offshore wind energy emerges an alternative. Motivated by the recent Swedish plans to develop offshore wind power capacity in the Baltic Sea, as well as the problematic environmental statues in the Baltic Sea, this work investigate the cost of green hydrogen produced from offshore wind energy in Sweden and evaluates the environmental impacts of utilizing by-product oxygen on the marine ecosystem in the Baltic Sea.  The first step of this work considers the economic feasibility of a 2 GW offshore wind energy dedicated for hydrogen production in the Baltic Sea outside Sweden, with three alternative electrolyzer placement: onshore electrolyzer (III), centralized offshore electrolyzer (II), and decentralized offshore electrolyzer (I). The proposed assessment of this work investigated the hydrogen production cost using electricity from offshore wind energy in the Baltic Sea in Sweden. The LCoE and LCoH in relation to three configurations reflecting the electrolyzer placement were analyzed and compared. The electrolyzer operation at nominal capacities of 06%, 65%, and 70% were considered for the three configurations. The results shows that the LCoE and LCoH differed between the three configurations. The results showed that the lowest LCoE and LCoH is achieved by the configuration where the electrolyzer system decentralized at the turbine platform at a price of 1.7 €/kg. Reflecting the impact of the electrolyzer nominal capacities, which are at 60%, 65%, and 70%, on the LCoH, the result showed that the three configurations are equally competitive. However, when the nominal capacity of 65% were compared among the three configurations, it was showed that the LCoH at the onshore electrolyzer were 2.6 €/kg compared to the LCoH at the centralized electrolyzer which resulted in LCoH of 2.7 €/kg. The second step of this work considers the evaluation of the environmental impact of artificial oxygenation by reviewing existing studies. The results of the reviewed studies on the environmental impacts of artificial oxygenation indicate that the utilization of the by-product oxygen would contribute to important environmental benefits for the Baltic Sea. The use of the by-product oxygen to oxygenate would maintain the processes that removes nutrients, keep the sea water oxygenated, and the seabed habitable for marine animal. There are, however, some aspects that need to be considered and understood when planning for oxygenation, such as the complicated physical and biogeochemical interactions. Hence, this requires further studies and investigations.