Energy carrier allocation strategy for a hybrid wind farm with offshore electrolysis

Abstract

Hydrogen is emerging as a promising energy carrier that can potentially solve the challenges like long-term storage and intermittent power supply associated with a 100%-renewable economy. Moreover, hydrogen can be used in industry sectors such as steel manufacturing and aviation, which struggle with carbon abatement. To increase the supply of green hydrogen, the European Union aims to have at least 40 GW of renewable energy sources connected to electrolysis by 2030. In light of this ambition, the Dutch government recently issued an offshore wind tender that should incorporate 500 MW of offshore electrolysis capacity.

A hybrid farm with offshore electrolysis contains both a hydrogen pipeline and an electricity cable as the export connection to shore. Appropriately sizing these connections to ensure financial feasibility becomes a design challenge for wind farm developers as the technology is still maturing.

This study considers a case study of an offshore hybrid wind farm situated in the European North Sea, connected to the Dutch energy infrastructure. A Python model was developed to simulate the sales and production of hydrogen and electricity on an hourly time scale. The simulation was executed by using historical data for electricity pricing and assuming a perfect forecast from a developer’s perspective. The objective function was to determine the optimal ratio between electrolyzer and electricity cable capacity (EC ratio) to maximize the net present value (NPV) of such a project. A sensitivity analysis on various system parameters was performed, and multiple scenarios reflecting potential future circumstances were simulated.

The study revealed that both oversizing and downsizing the total export capacity was not beneficial. Instead, the optimal EC ratio followed a linear trend, where the sum of connection capacities equaled the total farm capacity. The hydrogen price, electricity price, and nominal efficiency of the electrolyzer were identified as key factors influencing the optimal EC ratio.

This research establishes optimal EC ratios for a range of hydrogen prices spanning from €3/kg to €8/kg based on different scenarios. For each scenario, different electricity prices and electrolyzer specifications were defined. The findings indicate that including an electrolyzer in the design is not economically viable for hydrogen prices below €4.00/kg. Conversely, an electrolyzer-dominated system becomes favorable in each scenario when the hydrogen price
exceeds €7.50/kg. For prices in between, optimal EC ratios resembling hybrid systems were identified depending on the other key parameters defined by the scenarios.