Arðsemisgreining á vetnisframleiðslu með bestun á orkunotkun Fljótsdalsstöðvar

The Icelandic government has set ambitious goals to achieve carbon neutrality before 2040 and to cut green house gas emissions by 40% before 2030. In this process, there are many obstacles to overcome, among them the energy transition for long-distance transport on land and sea. To that end, "green" hydrogen, i.e. hydrogen produced using renewable sources, is a viable option as fuel cell development has proven successful. Political and public inertia has caused stagnation for the implementation of new power plants, while the call remains strong for sustainable utilisation of the current energy infrastructure. Therefore, this thesis aims to analyse hydrogen production using available energy at a domestic hydro-power plant. At Fljótsdalur station, the annual potential energy loss from overflow is commonly > 1, 000 GWh. The transmission system from Fljótsdalur is relatively isolated, limiting the possibility of transferring electricity where needed. Historical data from Landsvirkjun on daily available energy from Fljótsdalur station over a 7 year period provide the groundwork for this thesis. A seasonal forecasting algorithm is used to project the data to span 3 additional years, yielding a total period of 10 years, a common lifetime for the replaceable electrolyser stack. An optimisation model is proposed to find the optimal size electrolyser, given data on available energy, expenditure, and a cost model which considers the plant's capacity. Thereby, the optimal capacity may be determined, and levelised cost of hydrogen (LCOH) calculated. A total of 12 scenarios are analysed, i.e. alkaline (AEC) and proton exchange membrane (PEM) electrolysis cells, gaseous or liquefied hydrogen storage, and three electricity cost assumptions. A base-case scenario of AEC electrolyser with gaseous storage is further analysed. The optimal capacity of the base-case was 65 MW size of electrolyser, with an aver- age load of 89% over the 10 year period. The profitability of such an installation is substantial, with a net present value of 29 $MM and an internal rate of return of 20%. The LCOH ranges from 3.1 to 5.2 $/kg H2 for different electricity contracts, which is in line with the values found in literature. Liquefied hydrogen storage relies on low electricity cost, as it involves an energy intensive process. Hence, scenarios with liquefied storage are not as profitable as with gaseous storage. The base-case hydrogen production would have significantly decreased the overflow and provided on average 8,070 tonnes of hydrogen to the energy mix annually. Keywords: Hydrogen, Hydropower, Alkaline Electrolysis Cell, Proton Exchange Membrane, Energy Transition, OptimisationLandsvirkjun, Energy Research Fund 2023