Techno-economic system analysis of an offshore energy hub with an outlook on electrofuel applications

Abstract

The integration of cross-sectoral energy hubs into large-scale wind farms opens up existing structures to new applications and contributes to achieving renewable energy systems and climate protection targets. The offshore energy hub concept consists in establishing an artificially constructed energy conversion and distribution hub that addresses two energy-related markets by power supply to public grids and by potentially enabling the conversion of renewable electricity into hydrogen or ammonia and supplying it ashore. Hence, the energy hub concept enables smart integration of offshore wind power into gas grids. Power generation on demand from stored green gas is able to cover residual power loads at low carbon intensity. Electrofuel production provides also the opportunity to export renewable fuels for sectors with traditionally high greenhouse gas emissions, e.g., agriculture or transportation. In this contribution an energy hub system in the North Sea is modeled and simulated to determine production quantities and efficiencies of electricity, hydrogen and ammonia. When comparing the efficiencies of production, storage, and transport values of 45.1–65% for hydrogen and values of 52–52.3% for ammonia were determined. Re-conversion to electricity with fuel cells of both hydrogen and ammonia is less efficient and cost worthly than their use in electrofuel applications. Because of emerging and potential cost reductions a sensitivity analysis is performed where lower capital costs (50%) lead to cost reductions in hydrogen (42–45%) and ammonia production (40–42%). Results show that energy hubs can become sustainable pillars in future energy systems through improving cost-competitiveness of wind power.