Power to X: En fallstudie med avseende på lönsamheten i Sverige

Power to X, hereinafter PtX, is a conversion of electricity into some kind of energy carrier, such as gas or liquid. The purpose of the technique is often to store “excess” energy from renewable energy sources, usually wind power, in order to use it later. One aspect ofPtX is Power to Gas, hereinafter PtG, which involves the conversion of electricity often by the use of an electrolyser into a gaseous energy carrier, such as hydrogen or methane. The technology is a promising strategy for balancing the electricity supply in countries that striveto have near zero carbon dioxide emissions and have to rely on renewable energy sources. Another part of PtX that has received more attention lately and that may be important in the future, with more fluctuating electricity prices due to a larger share of renewableenergy in the energy systems, is the technique Power to gas to power, PtGtP. In PtGtP electrical energy, often with the help of anelectrolyser, is converted and stored in a gaseous energy carrier and later on when there is an electricity shortage it is converted backinto electrical energy through fuel cells. PtGtP can therefore be seenas a further development of PtG. The purpose of the study is therefore to investigate the potential forPtX, more specifically PtG and PtGtP in Sweden in terms ofprofitability. PtG was investigated considering production of hydrogenand methane where the hydrogen was sold as fuel for vehicles and the methane was injected into the gas distribution network in Stockholm.The methane production also results in surplus heat which was injected into the district heating network. To investigate this, a qualitativecase study was carried out on two hypothetical facilities. One fromthe Swedish company Euromekanik, that produces hydrogen and one from the German company Electrochaea that produces methane. Euromekanik’s facility was also used for the PtGtP application. The results weremainly based on the electricity prices of 2019. However, electricityprices for 2017, 2018 as well as more volatile electricity prices havebeen examined. Simulations of the input- and output flows in thefacilities have been performed in MATLAB and profitabilitycalculations have been performed using the net present value methodand the profitability index. A sensitivity analysis was conducted inwhich the values of the most important parameters were varied. The results regarding PtG in this study show that the idea ofproduction should take place when the electricity prices are low canbe rejected. The results also show that the conversion of hydrogeninto methane decreases the profitability. Running the PtG plant allhours of the year and producing hydrogen is therefore the mostprofitable design of the plant, even though this set-up still resultsin a negative net present value of approximately 24 MSEK after 20years. The result from the investigation of PtGtP shows that due tothe low system efficiency, the electricity sold back to the grid needsto have a price of 5000-6000 SEK/MWh for the plant to break-even when purchasing electricity a fourth of the hours of the year with thelowest electricity price. With the pattern and prices on the Swedish electricity market today this technique will not be profitable.However, both PtG and PtGtP will most likely have another value than solely the economic profitability in terms of energy storage andsystem balancing functions, though that has not been examined in this thesis