A distributed renewable power system with hydrogen generation and storage for an island

Abstract

This study aimed to find a distributed renewable power system with hydrogen generation and storage to meet the current Isle of Rum's energy demands. Five different systems (Case 2–6) were evaluated compared to the current power system (Case 1), with the inclusion of a hydrogen generation and storage subsystem acting as an energy storage medium in Case 3, 4, 5 and 6. Case 2 exhibited a 96.2% reduction in diesel consumption. Case 3 and 4 achieved a fully renewable generation mix through the addition of a hydrogen subsystem comprised of a 28 kW PEM electrolyser, 120 kg compressed storage and modified gen-set. Case 5 and 6 also achieved a fully renewable generation mix, meeting the domestic heating and full heating demands of the island respectively through the integration of heat pumps. Economic analysis showed that Case 2 exhibited the lowest cost, with a LCOE of £3.02/kWh, a 43% reduction from Case 1. Both Case 3 and Case 4 also had a lower LCOE than Case 1 of £5.02/kWh and £4.37/kWh respectively. This shows that the hydrogen subsystem designed can be an economically viable option despite its currently high CAPEX. Both Case 5 and 6 had the highest CAPEX of all systems, due to the additional generation technology required to meet the additional heating demand. However, they achieved the lowest LCOE at £1.86/kWh and £0.76/kWh, due to the high efficiency exhibited by the heat pumps used for the heating load.