The principal issues being addressed by Clean Current technology are the reduction of climate change gases and the conservation of hydrocarbon resources by displacing their consumption with renewable resources. Demand for electricity is growing, particularly in lesser-developed countries where population growth is highest. According to the OECD’s World Energy Outlook 2000, electricity consumption will almost double by 2020 from the 12 TW hours used in 1997.

New sources of energy are required and renewable energy will be preferred when costs are low enough to compete or when governments provide incentives for renewable energy development. For Instance, in the United Kingdom companies that generate electricity from renewable sources are given a tradable Renewable Obligation Certificate worth 3 pence per kWh (about US 5 cents).

Tidal energy is not new. Tidal barrage systems have been in operation for decades. They operate like a hydro dam by blocking a bay or inlet trapping the tidal inflows and releasing the water through relatively conventional hydroelectric generators. The tidal range (change in water level) of the bay or inlet is the critical factor as opposed to tidal current velocity. Although the technology required to harness tidal energy using barrage systems is well established, barrage tidal power is expensive and environmentally destructive. There is only one major tidal generating station in operation. This is a 240-megawatt (1 megawatt = 1 MW = 1 million watts) station at the mouth of the La Rance River estuary on the northern coast of France (a large coal or nuclear power plant generates about 1,000 MW of electricity). The La Rance generating station has been in operation since 1966 and has been a very reliable source of electricity for France. La Rance was intended as one of many tidal power plants in France, until their nuclear program was greatly expanded in the late 1960s. Elsewhere there is a 20 MW experimental barrage facility at Annapolis Royal in Nova Scotia, and a 0.4 MW barrage plant near Murmansk in Russia.

Free stream tidal current power development has, for the most part, consisted of the adaptation of wind energy concepts to an underwater application. The 300 KW demonstration projects in England (North Devon) and Norway look remarkably like underwater windmills, including the use of gearboxes. The water to wire efficiency of this technology peaks at about 40%. Clean Current technology uses a ducted bidirectional turbine with a variable speed direct drive permanent magnet generator to produce water-to-wire efficiencies greater than 50%. The simple design requires significantly fewer moving parts, thereby reducing costs and improving operation and maintenance in the salt-water environment. The technology is scalable, but is limited by water depths.