Hidden tidal tech could power Scotland’s coastal towns
In a remote stretch of the Highlands, a swift river has become the testing ground for a new kind of tidal energy. Engineer David Mummery recalls swimming across the river a decade ago, rope tied tightly around his waist, letting the current pull him under as he submerged his head. “As an engineer we do the maths and stuff,” he says, “but sometimes you can get a lot more from actually touching the water and feeling it.” While lying in the rapids, he imagined a compact tidal generator that could serve small coastal communities.
The concept evolved into the Swimmer Turbine, a 50‑kilowatt device named for Mummery’s river experience. Made from fiberglass and steel, the turbine sits on the seabed, invisible beneath the surface, and can generate enough electricity for roughly 30 homes. Early trials began in the early 2010s at a secluded site chosen to keep the prototype away from curious tourists and cameras. “You’re trying to be quite discreet because you’re working with new technology,” Mummery explains.
Unlike the large tidal installations that already dot Scottish waters – Nova Innovation in Shetland, MeyGen’s four 1.5 MW turbines in the Pentland Firth, and the 2 MW floating Orbital O2 at Fall of Warness – the Swimmer Turbine is ultra‑compact and low‑cost. Its design allows fishermen and local workers to assemble and install it from their own village harbours. “Can you imagine an IKEA furniture kit? You get a shipping container, open it up and there are about 20 components,” he says. “You bolt them together, follow a launch plan, and you’re in the water.”
Mummery’s career began in Guildford, where he earned a mechanical engineering degree from Surrey University. Before founding Flex Marine Power, he was a sought‑after consultant in the UK energy sector, spending time on nuclear decommissioning projects and designing robots to retrieve material from contaminated tanks. He moved north after meeting Jo, a student at Glasgow University; the couple now live in the city’s suburbs with three young children.
His relocation coincided with Scotland’s rise as a hub for marine power. In 2010 he took a secondment with Scottish Power Renewables on the pioneering Pelamis project in Orkney. The 180‑metre Pelamis P2, nicknamed the “sea snake,” was the first deep‑water floating wave machine to feed electricity into the national grid. Although Pelamis entered administration in 2014, it remains celebrated as a milestone in marine energy. “The industry is littered with examples of fantastic technologies and brave teams that take decades,” Mummery observes, “but at some point the market doesn’t step up and they falter. Some really good ones have lasted the course, but others have not and it’s sad.”
Mummery believes the United Kingdom has “phenomenal waters for tidal power.” Yet he felt a disconnect between large‑scale projects and the small coastal communities he visited. “I’d be out on boats around Scotland doing sonar surveys with all these really expensive pieces of kit,” he recalls. “The equipment was huge, utility‑scale, shipped from the mainland. All the people I was meeting in harbours or in the pub were fishermen. They were knowledgeable and interested. I thought we’ve got to do this in a way that they can take the lead.” That conviction drove the Swimmer Turbine idea.
In 2011 he left the big‑project world to launch Flex Marine Power and focus on his turbine concept. He spent countless hours sketching and refining a design that was smaller and lighter. He hired a student assistant and set up a sleek glass office outside Glasgow, only to discover that an engineer’s workshop does not always fit into a pristine space. “It was a lovely place, but I wasn’t allowed to take a hammer drill into the office,” he jokes, underscoring the practical challenges of turning a vision into a community‑scale solution.