North Sea offshore network and energy storage for large scale integration of renewables

Abstract

This review investigates different aspects of the realization of a North Sea offshore grid. The North Sea region has several characteristics that make large-scale integration of renewable energy sources attractive, such as large wind resources and huge hydro reservoirs in the North. A meshed offshore grid with underwater storage can contribute to facilitate sufficient flexibility in the system. The technical review reveals some aspects that need more research, particularly regarding the protection schemes. Furthermore, offshore storage solutions are under development. However, most other aspects are covered by readily available solutions. The greatest challenges seem to lie within standardization, cost-benefit sharing and harmonization of regulatory regimes of the surrounding countries. Nevertheless, several studies have shown highly promising economic benefits of establishing an offshore grid in the North Sea compared to traditional planning of point-to-point connections only.Keywords: offshore grid, HVDC, grid integration, renewable, energy storage, North Sea IntroductionThe integration of renewable power generation implies new challenging issues for the grid such as variability of energy input, frequency response, system power balancing and power market design. Moreover, renewable resources are often located far from the load centers. For future scenarios new transmission infrastructure and energy storage is needed. Consequently, the grid will be more flexible and the security of supply will be ensured. Depending on the grid layout, distance from load centers and geography, few power grids today will support renewable integration above 10%-30% without an elevated risk of outages [1][2][3][4]. To increase the renewable penetration either grid extensions or storage should be added to the system. Optimally, a combination of the two are implemented [4]. The North Sea region could very well be a first mover towards integrated grid and storage planning for high renewable penetration levels. The grid will connect the Northern European mainland, the UK and Scandinavia, with the goals of:• Harvesting offshore wind • Interconnect Europe's energy markets to enhance security, stabilize prices and increase cost efficiency • Provide large scale hydro balancing power to markets with high penetration of variable renewable production • Implement deep-water energy storage to balance fluctuations In addition, the offshore grid can connect to energy consuming facilities in the North Sea, such as oil and gas platform at the Norwegian sector, and thus reduce regional CO 2 emissions further. For reference, the total emission for the power generation of the Norwegian oil and gas sector equaled more than 9 million tons CO2-eqvuivalents for 2010. The power comes mainly from open cycle gas turbines with an average efficiency of approximately 33%, about half of what a modern onshore gas plant can achieve today [5].

The collocation feasibility index – A method for selecting sites for co-located wave and wind farms

“…In fact, a capacity of 135 GW of offshore wind energy might be feasible by 2030 while the current capacity of operational offshore energy is lower than 5 GW [39]. The total capacity of the study area is divided into 44% in the UK, 27% in Germany, 13% in the Netherlands, 7% in Denmark, 6% in Norway and 3% in Belgium [40]. Among the reasons that make the North Sea a great area for offshore projects, the abundant wind and wave resource are maybe the most important [39].…”

Assessment of Low-Loss Configurations for Efficiency Improvement in Hybrid Modular Multilevel Converters

“…High-voltage direct-current (HVDC) systems deliver flexible, highly controllable transmission network platforms, well-suited to the challenges of a future power system with high percentage of distributed and renewable energy sources in its energy generation mix [1]. The modular multilevel converter (MMC) enables HVAC-HVDC interconnection and currently represents the most competitive converter topology among all voltage-sourced converters (VSCs) for use in HVDC systems [2], [3].…”

A review of marine renewable energy storage

“…Such flexibility is increasingly critical as more intermittent generators come online through distributed architectures, smart grids, and utility‐scale renewable generation plants . Currently, energy storage is still an indispensable link in MRE systems . However, because of the unique marine circumstances and the slower development of MRE technologies, energy storage technology for marine renewables remains rather embryonic.…”

“…11,[16][17][18][19] Currently, energy storage is still an indispensable link in MRE systems. 20,21 However, because of the unique marine circumstances and the slower development of MRE technologies, energy storage technology for marine renewables remains rather embryonic. For example, the International Renewable Energy Agency (IRENA) and the Det Norske Veritas & Germanischer Lloyd (DNV&GL) both predict that large-scale deep water-coupled offshore wind generation and offshore energy storage systems will be commercially deployed before 2050.…”