The Isles of Scilly and Celtic Sea FLOW

Last week I took my first trip to the Isles of Scilly, representing Celtic Sea Power, where we briefed the local government on the floating offshore wind opportunity in the Celtic Sea. We also had the opportunity to meet with representatives from local businesses and organizations, and learn about the key interests and concerns for the islands with this new opportunity. As Project Officer for local energy modelling, I was particularly interested in finding out about the attitude towards net zero and low carbon technology in the islands; and in the legacy of the SMART Islands project, which aimed to support the community on the Isles of Scilly in moving towards a low carbon future.

My Monday morning was an early start; catching the first flight of the day from Land’s End Airport to St Mary’s on the SkyBus at 8:15. As well as being a very cool way to commute, it’s also a great way to get your first look at the Isles of Scilly!

Our first port of call was St Mary’s Harbour, for a meeting with the Harbour Master to discuss the potential for the harbour to support floating wind in the Celtic Sea. We also got some great insights on the attitude towards floating wind and low carbon technology in the Isles of Scilly.

As a designated Area of Outstanding Natural Beauty (AONB), and with tourism as it’s key industry, one of the main concerns around renewable energy for the Isles of Scilly is visual impact. However, a significant advantage of floating offshore wind is that it can access deeper waters than fixed wind, and therefore can be located much further offshore than fixed projects. Considering floating offshore wind will have very limited, if any, visual impact on the islands; this is much less of a sticking point than it has been previously. It is still really important that any development around the Isles of Scilly considers holistic impact and prioritizes the environment.

The electricity supply for the Isles of Scilly currently relies on a single 33 kV sub-sea cable from Cornwall to St Mary’s, which was installed in 1989. The cable has a capacity of 7.5 MW. A diesel fueled power station on St Mary’s provided power to the islands before the cable was installed, and is now used as a back up source of power incase of a problem with the sub-sea cable (Hitachi Europe Ltd, 2016). Being reliant on a single cable for their entire energy supply leaves the Isles of Scilly in somewhat of a vulnerable position; with such a great renewable energy resource right on their doorstep, wouldn’t it make sense for electricity generated from floating offshore wind in the Celtic Sea to be supplied directly to the Islands?

In 2015, a partnership was established between The Duchy of Cornwall, Tresco Estate, Council of the Isles of Scilly, Hitachi Europe Ltd and the Islands’ Partnership; working on a project called Smart Islands. The broad aim of the project was to support the community on the Isles of Scilly in moving towards a low carbon future. More specifically, the project aims included generating 40% of the islands’ electricity from renewables by 2025, and transitioning to 40% of vehicles on the islands being low carbon or electric by 2025 (Council of the Isles of Scilly, 2015). With the Smart Islands project now completed, I was very interested to find out about the legacy it had left behind.

The electric vehicle element of the Smart Islands project was apparently very successful on the Isles of Scilly. With a total of 9 miles of paved roads, battery life on electric vehicles is hardly an issue, so the Isles of Scilly really are the perfect place for electric vehicles!

Low carbon alternatives to fishing vessels on the Isles of Scilly haven’t really been explored yet. However, most of the fishing vessels on the islands operate within six miles of the coastline due to the depth of St Mary’s Harbour and are therefore mostly day vessels. Considering this, there may be an opportunity to explore the potential for battery powered vessels operating from St Mary’s Harbour, following from the success of electric road vehicles. Electric road vehicle charging stations are already fairly widespread on the Islands, extending the infrastructure to St Mary’s Harbour for electric vessels could be a feasible option. Especially if the Isles of Scilly had a direct supply of electricity from floating offshore wind in the Celtic Sea, it could be the perfect location to test battery powered day vessels.


While one of the aims of the Smart Islands project was to generate 40% of electricity for the Isles of Scilly from renewable sources, data from the Census in 2021 found that only 2% of houses on the Isles of Scilly use renewable energy for heating. A further 4% of houses use a combination of energy sources for heating that include a renewable source. 40% of houses on the islands still rely purely on electric heating. In comparison, 15% of houses on mainland Cornwall rely on electric heating, 2% have renewably sourced heating, and 1% use a combination of sources that includes at least one renewable source.

A phrase repeated several times during our visit was “a world in miniature.” The Isles of Scilly and mainland Cornwall share a number of similar problems with their energy supply. Both require an energy supply to remote, rural location. What makes the Isles of Scilly unique, compared to the rest of Cornwall, is that energy use is isolated. All electricity to the islands is currently supplied through a single cable, and used within a defined geographical boundary. With it’s relatively small size and population, the Isles of Scilly could be an ideal place to develop and test methods for creating an energy model, which could be scaled up for use on larger populations such as Cornwall.

Amelia Gaskell currently works on our Cornwall FLOW Accelerator project which is part funded by the European Regional Development Fund.


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