Hydrogen can be key in the energy system transition. We investigate the role of offshore hydrogen generation in a future integrated energy system, and its interaction with other system elements. By performing energy system optimisation in a model application of the Northern-central European energy system and the North Sea offshore grid towards 2050, we find that offshore hydrogen generation may likely only play a limited role, and that offshore wind energy has higher value when sent to shore in the form of electricity. Forcing all hydrogen generation offshore would lead to increased energy system costs (9-28 b\EUR2016/year by 2045). Under the assumed scenario conditions, hydrogen generation - both onshore and offshore - follows solar PV generation patterns. Combined with hydrogen storage, this is the most cost-effective solution to satisfy future hydrogen demand. Overall, we find that the role of future offshore hydrogen generation should not simply be derived from minimizing costs for the offshore sub-system, but by also considering the value that such generation would create for the whole integrated energy system. Based on our results, a stronger political effort to promote the integration of offshore wind in onshore energy markets via electrical connection is called for.

Offshore grids can have an important role in the transition of the energy system to sustainability. Although they require extensive infrastructure investments, they open up for the exploitation of a vast amount of additional resources and may be important to provide for part of the increasing electricity demand driven by sector coupling between the electricity, heat, and transport sectors. We show that the level of such sector coupling is decisive for the development of offshore grids. Performing energy system optimization in a model application of the Northern-central European energy system and the North Sea offshore grid towards 2050, we find that without sector coupling no offshore grid may develop, and that the higher the level of sector coupling, the higher the value of offshore grids. The electrification of the transport sector favors offshore grid development more than the electrification of the heat sector. Offshore grid infrastructure development can therefore not be discussed as a separate political topic, but seen in connection to sector coupling.

This work is part of an ongoing study, creatively named the “LowWind Project”, which is a collaborative effort between DTU and industry to design and eventually implement a 3.4 MW 100 W/m^2 low wind (LW) turbine with a hub height of 127.5 m, a rotor diameter of 208 m, and a cut-out wind speed of 13 m/s. This paper investigates at what price point this LW turbine becomes competitive in Northern and Central Europe’s energy system, as well as what impact the introduction of this technology has on the system. Similarly, the impact system flexibility has on LW investment is also analysed by limiting future transmission investment. Furthermore, this paper also analyses the amount of revenue this LW technology could generate compared to conventional turbines to further investigate the business case for this technology. The main finding here is that this LW technology begins to see investment at a 45% price increase over a conventional onshore wind turbine with an equal hub height (127.5 m) and a smaller rotor diameter (142 m vs 208 m). The addition of LW technology also leads to a reduction in transmission investment, and similarly, reductions in transmission capacity lead to further investment in LW technology. Lastly, it is shown that in the future Northern and Central European energy system, in wind dominated areas such as Denmark, this LW technology could generate revenues that are more than 120% higher than conventional turbines (per MW), making the case that this technology could be a worthy endeavor.

This paper analyses the role of sector coupling towards 2050 in the energy system of North Europe when pursuing the green transition. Impacts of restricted onshore wind potential and transmission expansion are considered. Optimisation of the capacity development and operation of the energy system towards 2050 is performed with the energy system model Balmorel. Generation, storage, transmission expansion, district heating, carbon capture and storage, and synthetic gas units compete with each other. The results show how sector coupling leads to a change of paradigm: The electricity system moves from a system where generation adapts to inflexible demand, to a system where flexible demand adapts to variable generation. Sector coupling increases electricity demand, variable renewable energy, heat storage, and electricity and district heating transmission expansion towards 2050. Allowing investments in onshore wind and electricity transmission reduces emissions and costs considerably (especially with high sector coupling) with savings of 78.7 EUR2016/person/year. Investments in electricity-to-heat units are key to reduce costs and emissions in the heat sector. The scenarios with the highest sector coupling achieve the highest emission reduction by 2045: 76% greenhouse gases reduction with respect to 1990 levels, which highlights the value of sector coupling to achieve the green transition.

This paper proposes a mathematical model to perform optimal operational planning of large-scale energy systems with high share of renewable energy. Furthermore, it analyses the influence of different unit commitment modelling approaches on the operational planning outcomes. The value of co-optimisation of electricity and heating sector is emphasized in this paper. The results show the influence of massive renewable penetration in the energy sector towards 2050, and how this influences generation from other sources such as thermal and hydro. Including unit commitment constraints with integer variables leads to more realistic behaviour of the units, at the cost of increasing considerably the computational time. Relaxing integer variables reduces significantly the computational time, without highly compromising the accuracy of the results. Neglecting the unit commitment constraints leads to inaccurate results in terms of underestimation of costs, curtailment, wind's and solar PV's average revenue per energy unit sold, price volatility, and to overestimation of the flexibility of thermal units. Hence, depending on the purpose of the analysis, it is recommended to consider carefully the choice of unit commitment modelling approach and acknowledge the limitations. When the focus is on prices and revenues, using unit commitment constraints with integer variables is preferable.