Engineers have long contended that power from ocean tides could make a major contribution as a renewable energy source. Why hasn’t it?
Many say that it’s because the optimal technology hadn’t been developed and there were too many technical problems. But now a number of players have been ramping up the development of new technology. Alstom and Voith Gmbh are two of a number of engineering companies gearing up, hoping that the development of new technology will jump-start the deployment of ocean sourced energy.
Tidal current electricity – sometimes known as tidal stream electricity – is clean, renewable, reliable and most importantly, predictable.
There is often confusion regarding the different types of tidal power, and indeed between tidal current power and wave power. To summarise:
- Wave energy converters: these harness the motion of waves, which are primarily generated by the wind
- Tidal lagoons and tidal barrages: a barrage is constructed across a bay or inlet to create a captive reservoir. The rise and fall of the tides produces a difference in height between the reservoir and the open ocean and this is used to drive turbines fitted in the barrage
- Tidal current or tidal stream: these turbines use the kinetic power of tidal currents in the same way that wind turbines use the movement of air. This type of generation has lower capital cost and minimal environmental and visual impact.
Sea water is 832 times denser than air, giving ocean currents an extremely high energy density, which means that tidal turbines have a smaller rotor size than an offshore wind turbine of equivalent power rating. Tidal turbines require less seabed for an equivalent amount of installed generation capacity when compared to wind power, because tidal turbines can be installed closer together within each array. Unlike traditional hydro power or tidal barrage schemes, tidal current power does not require significant alteration of the natural environment and has the obvious advantage of minimal visual pollution when compared to offshore wind.
Tidal energy’s greatest advantage over other alternative energy sources is that it is almost entirely independent of the weather and hence, although it is variable, it is also predictable. Other variable renewables, including wind, wave, solar and hydroelectricity are affected, on varying timescales, by climatic fluctuations which can create challenges for the balancing of the transmission system. Hydroelectricity is subject to seasonal changes and very vulnerable to droughts; available solar power varies at seasonal, daily and instantaneous timescales; and wind and wave climates fluctuate on both seasonal and very short term timescales. As water covers over 70% of the Earth’s surface, the oceans represent a vast source of energy.
Last year the American aerospace company Lockheed Martin entered into an exclusive partnership with global tidal energy leader Atlantis Resources Ltd. to develop technology, components and projects in the tidal power sector on a global basis. A specific project is focused on optimizing the design of a new 1.5-megawatt tidal turbine, the AR1500.
“By 2040, world energy demand is expected to dramatically increase,” said Tim Fuhr, director of ocean energy for Lockheed Martin’s Mission Systems and Training business. “Lockheed Martin’s technology, development and expertise in ocean systems and global system integration skills will enable the AR1500 to use powerful tides to produce safe, clean renewable energy for homes and businesses around the world.”
The AR1500 will initially support the MeyGen project in Scotland’s Pentland Firth and deployment in Canada’s Bay of Fundy. Once completed, the MeyGen project – the world’s largest tidal stream project under development – is expected to deliver up to 398 megawatts of power, enough energy to power 200,000 homes or up to half of Scotland.
“With us acquiring the MeyGen project, and receiving full consents to begin construction of the project’s first phase, it has been an amazing 12 months of growth for Atlantis,” said Tim Cornelius, chief executive officer of Atlantis Resources Ltd. “Our AR1500 development program with Lockheed Martin will ultimately deliver the rapidly growing tidal energy industry the most advanced, robust and powerful tidal turbine system available on the market.”