Optimal placement of P2X facility in conjunction with Bornholm energy island : Preliminary overview for an immediate decarbonisation of maritime transport

Abstract

Bornholm plays a central role in the future offshore power expansion in the Baltic Sea and as a node between future interconnections between countries. The necessity to store/convert surplus power puts Bornholm in position to be the first natural energy hub. Bornholm can be not only the centre for electrical equipment such as substations but also a centre for P2X production from offshore wind power. The production of electrofuels through P2X technologies can penetrate the transport sector in Bornholm, the hardest to decarbonise, starting with the highspeed ferries to Ystad and Køge, which use in Rønne Havn as their base. The needs to comply with existing and imminent stricter regulations create the necessity for an immediate transition, before a fleet renewal. Therefore, this study investigates the conversion of the hydrogen, produced using offshore wind electricity, into methanol, whose use as a fuel is mature and does not require substantial changes to the fleet. In this work, three placements for a P2X facility, with a size able to satisfy Rønne Havn demand, are investigated: inside the wind turbines, in Bornholm and Copenhagen. The following results are reached. o The fuel demand for the ferries in Rønne Havn, including all the operations in the port, is estimated to be 237,000 MWh per year (equivalent to 23,300 m3 diesel per year). o The high consumption, 134 MWh per round-trip, of the high-speed ferry currently used creates a barrier to the direct electrification of the ferry, due to high capital cost of the battery and low energy density. o If the electrolyser can access only the electric energy from a 2 GW offshore wind power park near Bornholm, the cost of producing hydrogen in Bornholm is lower than the case in which it is produced in Copenhagen or inside the wind turbine, with a cost of 3-4 €/kg. o The cost of producing H2 in Bornholm and transmitting it via a pipeline to Copenhagen is on the same range of producing the hydrogen in  Copenhagen. o The production of hydrogen in Bornholm benefits the utilisation of the HVDC line transmitting the remaining electricity to Copenhagen. o The cost of producing hydrogen is in line with the cost of green H2 in Europe (2.8-3.6 €/kg), but it is higher than its fossil counterparts, grey H2 (0.8-2.9 €/kg) and blue H2 (1.35-2.6 €/kg). The amount of CO2 potentially available from biomass, currently combusted in CHP plants and potentially available for anaerobic digestion, is estimated to be equivalent to 31,423 tonnes per annum, from which 22,853 tonnes per annum of methanol can be produced, equivalent to 126,325 MWh. Therefore, the CO2 is the limiting reactant in the methanol production if the plant is placed on Bornholm. o If the access to the public grid is guaranteed to maintain the production of methanol without shutdowns, a 62.4 MW electrolyser followed by a methanol plant would be required to satisfy the demand for ferries Rønne Havn. However, a 27.6 MW electrolyser would produce the amount of hydrogen that can be converted to methanol, considering the limited CO2 sources. o If the methanol production is placed in Bornholm to satisfy Rønne Havn demand, the green fuel can be produced at 800 €/t, in the case there is no limitation of CO2 sources, or at 867 €/t in case of limited CO2 sources. o If all the by-products of the electrolysis, oxygen and heat are sold, the cost of production of methanol is reduced to 590 €/t, or to 660 €/t in case of limited CO2 sources. o The cost of the methanol produced in Bornholm is in line with cost ranges for green methanol (260-1,060€/t.). However, the costs result higher than the selling price of fossil methanol ca. 275 €/t. o In conclusion, the placement of the P2X facility results to be more cost-effective in Bornholm, in the case of only-hydrogen production. However, if hydrogen is converted into methanol, the larger access to CO2 sources would favour the placement of the methanol production plant in Copenhagen. o The access to low-cost electricity from renewables and the efficient use of byproducts are vital for the production of electrofuels able to compete with the existing fossil counterparts.