Impact case study

The expansion of the offshore wind sector is leading to larger capacity wind farms. There are significant opportunities to exploit the existing electrical infrastructure for use in alternative renewable generation and maximise the output of each wind turbine footprint.

Wave energy converters (WECs) transform the kinetic energy of waves into electrical energy. The technology has yet to reach maturity due to diverse challenges including the development of efficient mechanical designs; high peak, low average wave power; and minimising the ecological impact. While the majority of existing projects focus on efficient and scalable designs of the physical WEC, work to explore the electrical integration of WECs into the distribution grid is limited, due to the varying nature of the power produced and challenges with synchronisation.

One potential solution is to integrate WECs into the existing electrical infrastructure of offshore wind farms. However, due to wave energy’s variability, most converters produce highly varied, low-voltage electrical outputs where the current varies on a multi-second basis. To enable integration into an offshore wind network, this variable output needs to be stabilised into a medium voltage waveform with a frequency of 50 Hz.  A typical way to achieve this conversion is via the utilisation of a power converter with a large step-up transformer. However, the magnetic core of transformers leads to low power density and introduces mechanical constraints for wave energy converters that need to float.

Integrating WECs into the existing electrical infrastructure of offshore wind farms would reduce the initial capital expenditure required to set up a wave energy farm. It would also limit the offshore renewable sector’s impact on the marine environment by optimising marine spatial usage. This type of hybrid renewable generation would reduce the intermittency of offshore renewable farms and our dependence on fossil fuel stopgaps.

The project’s long-term goal is to feed into a greater set of research in developing a power converter capable of reliable operation in the challenging offshore environment.

The immediate impact of the research includes collaboration between the University of Durham and the University of Edinburgh. This resulted in a £1.7M research grant and supported the recruitment of a postdoctoral researcher at Durham in expanding on the DC-DC converter technology developed during this project. In addition, new undergraduate and MSc student research has been undertaken, based on findings from this project and to examine adjacent applications of the technology. Novel research designs have also been presented as a conference paper at PEMD 2024 and are in the final stages of being written as a journal publication.