Marine Current Turbines has raised £7.5 million ($15 million) in funding to install and expand the application of what it says is the world’s largest, commercial-scale turbine used to generate energy from ocean tides and currents.

Marine Current Turbines (MCT) will use the funding, which comes from investment and savings bank Triodos Bank and hedge fund AM2, to build a commercial tidal energy farm in the next three to five years, a company representative said.

An emerging sliver of the renewable energy sector, ocean energy has been gaining ground in recent months, in its traditional home, the United Kingdom, as well as in North America. Tides, currents, and waves are predictable, unlike wind and even sunshine. But putting big steel turbines into the sea is a challenging proposition, as is building a large-enough system to make a dent in energy supply. MCT is the most recent test case for tidal power as a source of commercial-scale electricity.

MCT’s SeaGen turbine, which will be installed in the waters of Northern Ireland’s Strangford Lough in August, is capable of generating 1.2 megawatts of energy and supplying a thousand homes with electricity, by company estimates. But Bristol, U.K.-based MCT hasn’t yet nailed down a buyer for the electricity.

“The ultimate objective—although this seems crazy—is not to generate electricity,” said Paul Taylor, an outside spokesman for the company. “It’s to prove we can generate electricity over time” for the eventual application in a multiturbine tidal farm. MCT is considering the waters off the coast of northern Wales as a potential site for the dozen-turbine farm, Mr. Taylor said.

MCT’s devices appear to be a step up, at least in scale, from other offerings, which tend to generate between 20 and 300 kilowatts of electricity. Ireland’s OpenHydro Group is developing tidal energy farms off the Channel Islands, for example, while New York City-based Verdant Power is operating turbines in Manhattan’s East River. With a capacity of 1.2 megawatts, MCT’s SeaGen turbine consists of a single structure with twin blades and is reportedly four times larger than the largest existing tidal turbine. “Essentially, it’s like an underwater windmill,” Mr. Taylor said. The twin turbine is MCT’s second turbine design, following its 300 kilowatt SeaFlow turbine, developed in 2003 and tested off the North Devon Coast.

Prior to the most recent round of funding, announced last week, MCT received £3 million in funding in 2004 from EDF Energy, BankInvest, and Guernsey Electricity as well as a £3.85 million government grant in 2005, according to its web site. The company was founded in 2000.