Batteryboat

Abstract

Climate change, depletion of fossil fuels, and economic concerns are among the main drivers of sustainable energy transition. The Netherlands has drawn up ambitious goals in the energy transition. However, numerous studies have shown that there is a lack of space in the Netherlands to adapt to a 100% green economy. To solve this dilemma it is necessary to import renewable energy from other countries. Solar electricity prices are dropping rapidly in high solar irradiation areas and are currently the worlds cheapest source of electricity, likewise this is in places where space is often abundant. This thesis examines the techno-economical feasibility of importing solar energy from Morocco to the Netherlands. As subsidized solar electricity is bought by the Dutch government for 0.125 e/kWh, the target is to find a solution below this demand. All energy storage systems are analyzed thoroughly and an energy and cost analysis is performed for a cable, chemical energy storage, thermal energy storage and liquid air energy storage.
A HVDC submarine power cable between Morocco and the Netherlands is compared in proportion to the costs and distance of the NorNed cable. A HVDC submarine power cable over a distance of 2600 km results in a LCoE of 0.113 e/kWh. Other energy storage systems use a tanker to transport the stored energy. In this thesis liquid hydrogen, ammonia and methanol are analyzed as chemical energy storage systems. Liquid hydrogen is produced by cooling and expanding hydrogen, ammonia is produced by the Haber-Bosch process and methanol is formed by reacting H2 and CO2. Fuel cells are used to convert fuels back into electricity. The most efficient and cost effective solution for chemical energy storage is storing electricity in the form of liquid hydrogen. A round-trip efficiency of 27% with a LCoE of 0.491 e/kWh is obtained in 2015, from the predictions of 2030 a round-trip efficiency of 40% with a LCoE of 0.159 e/kWh is derived. The next concept is based on thermal energy storage with Solar Salt as energy carrier. Solar Salt is heated in the receiver of a solar tower where heat from the sun is concentrated to by heliostats. Hot Solar Salt is transported to the Netherlands by a tanker and a steam cycle is driven utilizing the heat of hot Solar Salt. The energy efficiency obtained from solar irradiation to electricity in the Netherlands is 28%, the output power is only 1% less than the output power should be if the power block was located in Morocco. An electricity price of 0.164 e/kWh is obtained, but if heat is delivered a heat price of 0.069 e/kWh can be realized. The final designed energy storage system combines liquid air with the heat of hot Solar Salt. Liquid air and hot Solar Salt are produced in Morocco and in the Netherlands electricity is produced with high efficiencies due to the large temperature differences. The system described results in a electricity price of 0.108 e/kWh with an energy efficiency of 58.7% from electricity and hot Solar Salt to electricity in the Netherlands.
It is concluded that storing electricity in chemical energy storage via the processes described in this thesis will lead to too high costs to be used as energy storage solution. There are possibilities in direct fuel conversion technologies due to high conversion efficiencies, only developments are still in its experimental phase. The combination of liquid air with Solar Salt complies to the cost requirement, some more research is required on the electricity generation process described, but the concept shows a lot of potential. Finally, heat of Solar Salt can be provided at a price of 0.069 e/kWh, subsidized solar heat is bought by the Dutch government for 0.095 e/kWh. This gives possibilities to effectuate a business case.