Marine Energy in Scotland

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Written for Coursera (MOOC) Class ‘Ocean Solutions‘ by University of Western Australia (June 2014)

EMEC Kawasaki Tidal

Scotland is host to the European Marine Energy Centre, located on the Orkney Islands, off the north coast.  It opened in 2003 and is the only centre of its kind in the world for both wave and tidal energy testing.  The centre is an internationally acknowledged leader in marine energy and assists in the development of industry standards and guidelines.

BBC: Tidal energy: Pentland Firth ‘could power half of Scotland’ (20 January 2014)

BBC: Pentland Firth tidal turbine project given consent (16 September 2013)

Scottish Government: Marine Scotland – Marine and Fisheries, Offshore Renewable Energy

European Marine Energy Centre (Orkney, Scotland)

Tidal energy projects at the EMEC include:

  • Andritz Hydro Hammerfest (HS1000) 1 MW
  • Atlantis Resources Corporation (AR1000) 1 MW
  • Bluewater Energy Services (BlueTEC)
  • Kawasaki Heavy Industries (sea-bed mounted horizontal axis) 1 MW
  • Open Hydro (Turbine) 250 kW
  • Scotrenewables Tidal Power Ltd (SR250, SR2000) 250 kW & 2 MW
  • Tidal Generation Ltd (Deepgen) 500 kW
  • Voith Hydro (HyTide) 1 MW

Wave energy projects at the EMEC include:

Hydrokinetic Energy is the transfer of energy from natural water motion to usually electrical energy for consumption.  Hydro energy is a well established and widely adopted form of this technology associated with rivers and dams.

The leading current marine hydrokinetic designs are described below.  Taken from the Union of Concerned Scientists website.

Oscillating Water Column.  ‘Waves enter and exit a partially submerged collector from below, causing the water column inside the collector to rise and fall. The changing water level acts like a piston as it drives air that is trapped in the device above the water into a turbine, producing electricity via a coupled generator.’

Point Absorber: ‘Utilizes wave energy from all directions at a single point by using the vertical motion of waves to act as a pump that pressurizes seawater or an internal fluid, which drives a turbine. This type of device has many possible configurations. One configuration, called a hose pump point absorber, consists of a surface-floating buoy anchored to the sea floor, with the turbine device as part of the vertical connection. The wave-induced vertical motion of the buoy causes the connection to expand and contract, producing the necessary pumping action. Through engineering to generate device-wave resonance, energy capture and electricity generation by point absorbers can be maximized.’

Attenuator:Also known as heave-surge devices, these long, jointed floating structures are aligned parallel to the wave direction and generate electricity by riding the waves. The device, anchored at each end, utilizes passing waves to set each section into rotational motion relative to the next segment. Their relative motion, concentrated at the joints between the segments, is used to pressurize a hydraulic piston that drives fluids through a motor, which turns the coupled generator.’

Overtopping Device: ‘A floating reservoir, in effect, is formed as waves break over the walls of the device. The reservoir creates a head of water—a water level higher than that of the surrounding ocean surface—which generates the pressure necessary to turn a hydro turbine as the water flows out the bottom of the device, back into the sea.’

Rotating devices: ‘Capture the kinetic energy of a flow of water, such as a tidal stream, ocean current or river, as it passes across a rotor. The rotor turns with the current, creating rotational energy that is converted into electricity by a generator. Rotational devices used in water currents are conceptually akin to, and some designs look very similar to, the wind turbines already in widespread use today – a similarity that has helped to speed up the technological development of the water-based turbines. Some rotational device designs, like most wind turbines, rotate around a horizontal axis, while other, more theoretical concepts are oriented around a vertical axis, with some designs resembling egg beaters.’

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