Towards the introduction of green hydrogen in the energy mix of Mediterranean islands through the integration of wind and solar power: a techno-economic case study

Mediterranean islands have always struggled with power supply, with the high cost of electrical submarine cables prompting the pursuing of energy self-sufficiency with renewable energy sources (RES). Despite being clean and sustainable, RES are intermittent and unpredictable, hence the integration of a storage system is crucial to match load with production. Modern batteries are a valuable solution for short term storage/but they are unsuitable for long term storage for both technical and economic reasons. Green hydrogen is among the most promising options to enable a year-long autonomous operation, but it is still an expensive option, with many technical issues that still need to be addressed. One of the key factors hampering a reduction of the levelized cost of green hydrogen (LCOH) is the low number of working hours that an electrolyzer can exploit when connected to low-capacity factor RES. Starting with real production data of a wind turbine and a PV farm in a Mediterranean island, this study aims to assess the optimal combination of wind and solar power to decrease the LCOH (intended as its production cost only) and thus the cost of storage. The study is made of three steps. First, a comprehensive parametric optimization is carried out to determine the optimal combination of electrolyzer and PV field size to minimize the LCOH produced from the surplus power generated on the island. Secondly, an additional analysis is performed to calculate the minimum PV field expansion required to achieve a complete energy self-sufficiency and to estimate the resulting LCOH in such case. Lastly, the implementation of a fleet of hydrogen buses is proposed to both reduce the carbon footprint of the island transportation system, and further lower the cost of hydrogen production.