An Introduction to Marine Renewable Energy
Summary There are two main forms of marine renewable energy; wave power and tidal power. Energy contained in a wave depends upon its size. Energy from the tide is obtained in two forms (i) exploiting changes in the sea level (tidal range) and (ii) utilising the flow of the water (tidal stream). This project focuses primarily on tidal stream energy.
Tidal stream power generation requires a flow rate of ≥ 2 m/s in order to drive a turbine and achieve power generation. These sites are generally found where water is restricted by land, such as near headlands or through channels. Studies examining flow rates located around Wales have shown several suitable locations for tidal stream power generation.
The UK has an estimated 18 TWh per year of tidal energy resource, which equates to approximately 5% of UK electricity demand. This will, undoubtedly, help to achieve the renewable energy targets of 20% by 2020. The UK tidal resource is approximately half the total extractable power for the whole of Europe. Initial installations at the most attractive sites are targeted at 1-2.5GW in Europe, at a price of 9-18p/KWh, falling to 5-7p/KWh as technologies mature.
Many tidal stream turbine designs are in development, with research, testing and commercialisation boosted by the creation of the European Marine Energy Centre (EMEC) in Orkney. Further support under the Renewables Obligation (RO) could lead to tidal stream devices qualifying for a premium of around 10p/KWh produced.
Marine renewable energy consists of two main types; wave power and tidal power.
Wave powerEnergy in a wave varies in phase with each wave. The amount of energy available from a wave depends on its size, predictable around 120 hours in advance. A high density of wave energy exists on the Welsh Atlantic coast due to the large waves created by the long fetch of the Atlantic coming to shore in this location.
Tidal stream powerTidal power is the production of electricity from the natural power contained in tidal flows. This energy is renewable, predictable and produces no emissions, making it a very attractive source of power. There are two main methods of harnessing the power from tides (i) by exploiting the change in sea level such as tidal barrage systems, and (ii) by harnessing the flow of water; such as tidal stream systems. Both of these methods pass water through devices that convert the energy in the water to electrical energy. The rest of the information here will focus on tidal stream energy.
There are points generally near land such as headlands or channels where geographical restrictions increase the speed of flow, concentrating flow energy density. Locations of interest for tidal stream energy are the points where the peak flow rate exceeds 2m/s. Because the tide does not flow at the same time everywhere and these sites are located around Britain, the net result of the electrical energy obtained could contribute to base load power in the UK. A study examining flow rates showed that Wales has several sites identified as being suitable for capturing tidal stream power.
It has been estimated that the UK alone has around 18TWh per year of tidal power resource; which equates to approximately five percent of the nation’s electricity demand, greatly helping towards the government target of achieving 20% renewable energy by 2020. Investment in the region of approximately three billion pounds is required over the next fifteen years to fully exploit this resource. The UK has an excellent density of extractable tidal power with approximately half the total extractable power for the whole of Europe. A significant proportion of this power is around the Welsh coastline.
Government Policy on Tidal Power in the UKIt is recognised widely that the tidal stream sector is currently reaching a critical stage of development. As outlined in the Department of Energy and Climate Change’s current consultation on the Renewables Obligation Banding Review, the challenge for the sector is currently reaching a critical stage of development. As outlined in this review, the challenge for the sector is to move from a Research and Development focus, to the demonstration of small arrays (in the region of 5 to 10MW), to successful commercial scale deployment in the period to 2020.
What is reassuring to note is that the UK Government has recognised the potential of marine energy, stating ‘we will introduce measures to encourage marine energy’. This is evident by the proposal to provide 5 ROCs/MWh for each tidal stream project up to a limit of 30MW, and the current level of funding to date from UK Government and Devolved Administrations. One example where funding is being used to help bring forward the marine energy sector is the Low Carbon Research Institute (LCRI) Marine.
Low Carbon Research Institute MarineLCRI Marine is a collaboration of all the leading academic marine institutions in Wales. The LCRI Marine project aims to build a sustainable marine energy sector in Wales. It provides the independent and world class research essential to move the industry forward, first to small scale and subsequently to full scale generation of electricity from the marine environment. In addition to the development and application of tools for optimising the performance of the technology, the team evaluates technologies to recover energy from waves, tidal streams and tidal range around the Welsh coast. In particular, the group considers the likely effects that these devices have on the environment, such as their effects on the seabed communities, on sediment transport and on marine wildlife.
Training Developed as part of WESTAs part of the Welsh Energy Sector Training Programme, three courses giving an introduction to marine renewable energy with a focus on tidal stream energy have been developed. Brief details are outlined below:
An introduction to marine renewable energy- Introduction to wave and tidal energy resources
- Device design considerations
- Current market and example technologies
- Introduction to tidal stream energy data sources
- Examination of baseline selection criteria
- Power output estimation methodology
- Description of devices and potential receptors
- Assessment of risks
- Impact assessment of tidal stream turbines.
Dr Ian Masters: i.masters@swansea.ac.uk
Tel: 01792 295688
Dr Miles Willis: i.masters@swansea.ac.uk
Tel: 01792 295541
Dr Sherryl Bellfield: s.l.bellfield@swansea.ac.uk