Scotland — Engineer's 50kW 'Swimmer Turbine' Targets Coastal Grids

A 50kW tidal generator developed by engineer David Mummery can produce enough electricity to power about 30 homes, according to Mummery, founder of Flex Marine Power, speaking to BBC News. The device, called the Swimmer Turbine, has been tested at a secret Highlands river site and at Strangford Narrows in Northern Ireland, and Mummery says it could change the economics of power generation for coastal communities.

What is the Swimmer Turbine and how big is it?

The Swimmer Turbine is a small-scale tidal device built from fiberglass and steel, anchored to the sea floor and invisible below the water's surface, BBC News reports. Mummery named it after the method he used to design it: he tied a cord across a fast-flowing Highland river, swam out, and let the current pass over him to understand how a turbine would need to interact with that environment. The 50kW rating distinguishes the device from the much larger tidal arrays already operating in Scottish waters.

Why was it developed in secret?

Mummery began testing the design in the river in the early 2010s, working at a location kept hidden from tourists on a patent lawyer's advice, according to BBC News. "You're trying to be quite discreet because you're working with new technology," he told the broadcaster. The secrecy predated what BBC News describes as Britain's energy-cost crisis, placing the early development work years ahead of the current push for domestic power alternatives.

How does it compare with Scotland's larger tidal projects?

Scotland already hosts some of the world's most prominent tidal installations, per BBC News: Nova Innovation deployed the world's first tidal stream array at Bluemull Sound in Shetland in 2016; MeyGen operates four 1.5MW turbines on the seabed of the Pentland Firth, making it the world's largest tidal array; and Orbital's O2, anchored at Fall of Warness in the Orkney Islands, generates 2MW as the world's most powerful floating turbine. Mummery's device is built to a different scale entirely — compact and low-cost rather than industrial-sized.

Can local workers install it themselves?

Mummery told BBC News the turbine is designed to be assembled by fishermen and local workers rather than specialist marine-engineering crews. "Can you imagine like an Ikea furniture kit? You get a shipping container and you'll open it up and it will be about 20 components," he said. "You'll bolt them all together and then you've got your turbine ready. There'll be a launch plan, you follow these instructions, then you'll be in the water." BBC News notes fishermen on Islay have already taken part in assembling the turbine.

Who built Flex Marine Power?

Mummery, originally from Guildford, studied mechanical engineering at Surrey University and worked as a consultant in the UK energy sector before founding Flex Marine Power, according to BBC News.

Tidal Power Snapshot

• Swimmer Turbine: 50kW capacity, powers roughly 30 homes, per Flex Marine Power via BBC News
• MeyGen (Pentland Firth): four turbines rated at 1.5MW each, the world's largest tidal array, per BBC News

Glossary

Tidal stream turbine: a device anchored underwater that generates electricity from the motion of tidal currents, similar in principle to a wind turbine but driven by moving water.