Tidal energy – harnessing earth-moon energy

If the barriers of cost, reliability and efficiency are overcome, tidal power all but guarantees limitless, clean and predictable energy. Conservative estimates show that the ocean energy industry, including wave and tidal energy, will supply ten per cent of the global energy demand in the future.

Tidal energy – produced by the predictable and powerful rise and fall of tides – is an emerging market that has been identified as a potentially important global source of renewable energy.

One of the most powerful tidal areas in the world is the Orkney waters off the northern coast of Scotland. This area, including the waters around the Orkney Islands – also known as the Saudi Arabia of tidal power – contains 50 per cent of the UK’s tidal resources, and 25 per cent of Europe’s. This is where Orbital Marine Power Ltd., a Scottish tidal turbine device developer, is deploying its technology.

The company has commercial applications of tidal energy squarely in its sights, and they have been collaborating with SKF’s ocean energy team on a joint project to use floating tidal turbine technology to reduce the costs of generating electricity. The SKF team has helped with rotational equipment performance all the way from the prototype stage to full commercialisation.

Essentially, the basic powertrain components and system configurations of a tidal turbine are similar to those of a wind turbine, although the technology must withstand a dense and wet environment. ‘It’s more sophisticated because it has to deal with the challenges of the harsh marine environment in a tidal stream,’ says Orbital CEO Andrew Scott.

One key to the commercialisation of tidal turbines is the development of a pitch controller for the tidal turbine blades. Orbital Marine Power are targeting up to a 50 per cent increase in yield from their machines, bringing performance in line with more established technologies. ‘The easiest way to reduce the overall cost of energy is by being able to use longer rotor blades so they capture more energy from the tidal current,’ Scott explains.

However, as the blades get longer, the resulting loads become heavier and more challenging. A pitch controller system enables Orbital to feather the blades so that they can control those loads far more accurately – an important solution to improve the economics of tidal energy further.

The market potential for tidal energy exceeds 100 gigawatts, but the constraints on harnessing tidal energy have really revolved around the cost of technologies to capture it. Markets will grow as investors and governments increase their confidence and awareness of the solution that tidal energy can offer.

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