Marine Current Turbines^TM Ltd is pioneering technology to exploit currents in the seas whether they are driven by the tides or by oceanic circulations.  This technology  is part of a family of energy technologies at varying stages of development, including tidal stream or tidal kinetic energy conversion, tidal barrage, wave, Ocean Thermal Energy Conversion, etc.  These are collectively referred to as “marine renewables”. Marine current energy shares a number of advantages over other marine renewables and those under development, as well as over the more traditional energy generation technologies currently in use.
 
Importantly marine currents are a low carbon energy resource capable of making a significant contribution to our efforts to reduce carbon emissions and increase energy security. In their report, “Future Marine Energy (2006)”, the Carbon Trust estimated that tidal stream energy could meet 5% of the UK's present electrical energy needs, reducing the country's dependence upon carbon intensive imported fossil fuels.
 
Moreover unlike other marine renewables, wind or wave energy, which respond to the more random effects of the weather system, tidal flows are as predictable as the tides that cause them. Predictability is a huge advantage in electricity generation, because it enables more efficient grid management, and thus reduces the total amount of power that needs to be generated.
 
Like wind turbines, MCT's SeaGen tidal turbine is a modular technology. A number of SeaGen units will be deployed together much like wind turbines in wind farms.  Just like wind, the technology will benefit from economies of scale and learning curve effects to reduce costs and improve efficiency. The cost of a wind electricity generation has dropped by 75% in real terms over the last 25 years since the first wind farms were installed in California. This contrasts with other marine renewables, like tidal barrages, which are “one offs” and which therefore will require different design and engineering solutions in each location and will require long lead times between investment and gaining any return.
 
Unlike wind, because water is much denser than air, the size of turbine needed to extract energy underwater can be much smaller than a wind turbine.  An additional advantageous difference is that, tidal stream devices can be packed closely together.

It should be noted that, all other things being equal at a given location, there are three factors which govern the energy capture by any water current kinetic energy converter such as MCT’s SeaGen system – the swept area  of the rotor(s) which governs the cross-section of natural resource that can be accessed – the speed of the flow (kinetic energy is proportional to the velocity cubed so the “bottom line” is very strongly influenced by current flow patterns and strengths – and the overall efficiency of the system (SeaGen uses technology analogous to modern wind turbines and is therefore one of the most efficient mechanisms for this purpose that it is possible to build).

For further information on tidal and marine energy see:

The Carbon Trust Future Marine Energy

The Sustainable Development Commission Tidal Power in the UK