What is It?
Tidal stream energy presents one of the most exciting emerging forms of renewable energy. Tidal streams, unlike many other forms of renewable energy, are a consistent source of kinetic energy caused by regular tidal cycles influenced by the phases of the moon. Intermittency is a problem for wind, wave and solar power as the sun doesn’t always shine and the wind doesn’t always blow. These sources of renewable energy often require backup from traditional forms of power generation. However, the inherent predictability of tidal power is highly attractive for grid management, removing the need for backup power from back-up plant powered by fossil fuels. Tidal turbines are installed on the seabed at locations with high tidal current velocities, or strong continuous ocean currents and extract energy from the flowing water.
How it Works
Tidal turbines are very much like an underwater windmill where the blades are driven by consistent, fast-moving currents. The submerged rotors harness the power of the tidal streams to drive generators, which in turn produce electricity. Water is 832 times denser than air so consequently tidal turbine rotors are much smaller than wind turbine rotors generate equivalent amounts of electricity, and they can be deployed much closer together.
Devices that harness tidal stream energy present a unique set of engineering challenges in terms of design, installation and maintenance. During operation, the force of the tidal flow in Strangford Lough is equivalent to a 345 mph wind generating a 100 tonnes of thrust on the rotors.
Against the backdrop of climate change and energy security, the European Union have set a target to obtain 20% of their energy generation from renewable sources by 2020. The UK Government have signed up to this agreement and have furthermore pledged to reduce the UK’s carbon emissions by 80% of 1990 levels by 2050.
The UK currently generates just under 10 % of its power from renewable resources and the UK Government has committed to increasing this percentage over the coming decade. Approximately 25% of the UK’s existing stock of fossil fuel power generation is due to come offline by 2020 whilst energy demand during this period is predicted to increase. The Fukushima nuclear disaster in Japan and political instability in the Middle East have highlighted the issues of energy security and rising energy costs to the UK and Europe .
Viewed against this backdrop there is a strong case for supporting the UK Government’s drive towards renewable energy. Vast quantities of predictable, reliable and consistent tidal stream energy are available in UK waters and beyond, and this form of electricity generation can play an important part in the future global energy mix.
The Benefits of Tidal
In addition to helping reduce carbon emissions, the tidal energy sector can bring significant economic benefits. Tidal energy has the potential to power 15 million homes, save 70 million tonnes of carbon and create 16,000 jobs in the UK alone. The UK Government has indicated that it will offer 5 Renewable Obligation Certificates (ROCs) to tidal energy projects that are installed and operational by 2017. This Government backing will be crucial in attracting the necessary private investment to ensure that the UK retains its position as the global leader in the tidal energy sector.
While estimates of global potential may vary, it is widely agreed that tidal stream energy capacity could exceed 120GW globally. The UK has one of the largest marine energy resources in the world, estimated to be more than 10GW, representing about 50% of Europe’s tidal energy capacity.