North Sea Renewables Grid

Although critics of wind power suggest that wind is a variable energy source and can’t be relied upon to keep the lights on, this isn’t actually the case when wind power is distributed over a large area like the North Sea. Variations in production at one wind park can be partly balanced by that of another park several hundreds of kilometres away.

To demonstrate this concept, Greenpeace commissioned a report based on what would happen if real wind speeds over the North Sea were applied to more than 100 envisioned wind power projects with 10,000 turbines. If all projects from Belgium, Denmark, France, Germany, Great Britain, Netherlands and Norway were built there would be an installed capacity of 68.4Gw.

The top graph below shows how the power output of the propose London Array would fluctuate with changing wind speeds. When combined with all wind farms around the British east coast, the power production starts to level out as a dip in generation around London could be offset by heavy winds around Scotland. The final graph shows how wind production stabilises even more when combining all wind farm output from countries bordering the North Sea.

To capitalise on the balancing nature of distributed wind farms, a large North Sea grid spanning 3,850 miles would be required to connect all of the wind farms together. Such a grid would facilitate trade and increase security of supply by dispatching power from offshore wind farms to different countries depending on the highest demand. Moreover, an offshore grid allows the import of electricity from Norwegian hydro power plants to Britain and other countries. For some hydro plants, excess power (when the wind blows and sun shines) can even be used to pump water back into reservoirs, working like a huge water-battery. Biomass from European countries could also be fed into this grid.

A system of this nature with many thousands of wind turbines is more reliable, and energy production more secure because the impact of maintenance or defects will be negligible when compared to a large coal or nuclear plant going off line. Another advantage of a North Sea grid is that any future wave power, floating wind Turbines and tidal power stations could also be connected up to provide more power, stability and distribution of power between countries.

If this proposal were to be implemented then 70 million homes or 13% of the annual electricity consumption of the seven European countries could be met.

For the full report, see
http://www.greenpeace.de/fileadmin/gpd/user_upload/themen/energie/offshorewindgrid_final.pdf

Greenpeace Eco City

If a picture speaks a thousand words, a multimedia-packed, animation-filled interactive town must speak a million. Which is why Greenpeace have launched EfficienCity - to exlain exactly what decentralised energy is and how it works in practice (which can otherwise be a wordy business).

If you still believe the government and think we need nuclear power and coal to stop climate change, come and pay a visit to EfficienCity, which shows how pioneering, real world communities around the UK are using decentralised energy. As a result, they're enjoying lower greenhouse gas emissions, a more secure energy supply, cheaper electricity and heating bills and a whole new attitude towards energy.



See:
http://www.greenpeace.org.uk/files/efficiencity/index.html
http://www.greenpeace.org.uk/efficiencity/about

Wave Power

Ocean waves represent a considerable renewable energy resource. Waves are generated by the wind as it blows across the ocean surface. They travel great distances without significant losses and so act as an efficient energy transport mechanism. Waves generated by a storm in mid-Atlantic will travel all the way to the coast of Europe without significant loss of energy.

All of the energy is concentrated near the water surface. This makes wave power a highly concentrated energy source with much smaller hourly and day-to-day variations than other renewable resources such as wind or solar. Conveniently, the seasonal variation of wave power closely follows the trend for electricity consumption in Western Europe.

The western seaboard of Europe offers an enormous number of potential sites. The most promising sites are off the UK, Ireland, France, Spain, Portugal and Norway. There is sufficient energy breaking on the UK shoreline to power the country three times over.  However, it is not practical to recover all of this energy. The economically recoverable resource for the UK alone has been estimated to be 87TWh per year, or about 25% of current UK demand.

See http://www.pelamiswave.com/ for more details about wave power.

Energy Generation: TidEL Tidal Power

SMD Hydrovision has developed a device for the extraction of energy from tidal flows. The TidEL concept consists of a pair of contra-rotating 500kW (kilowatt) turbines, mounted together on a single crossbeam. The complete assembly is buoyant and tethered to the seabed by a series of mooring chains. The mooring system allows the turbines to align themselves down stream of the prevailing tidal flow without requiring any external intervention, providing a reliable and economical way of tracking the alternating tidal flow-cycle. As the system requires no support structure, it can be fitted in any reasonable coastal water depth.

At present SMD Hydrovision is in the process of testing a 10th scale device in a specially developed tidal facility. The results of this testing will feed into the development of a full-scale prototype with 15 meter diameter fixed pitched blades driving the turbine powertrains that are housed within a pod.

For more information go to: http://www.bwea.com/marine/devices.html

Energy Generation: Seagen Wave Power

Marine Current Turbines Ltd is an independent company dedicated to developing a revolutionary technology for large-scale generation of clean electricity from the seas. MCT's patented technology is a submarine tidal current turbine based on using pitch regulated axial flow rotors, which has proved to be the successful formula for the vast majority of wind turbines and which seems likely to be the definitive solution for water current energy conversion too.

An experimental 300kW (kilowatt) test system, called "Seaflow" was successfully installed off Lynmouth in Devon in May 2003 and continues to deliver vital data. This is the world's first successful offshore tidal turbine and is the first step in developing this entirely new clean method of power generation. Seaflow is unique among "wet renewable" technologies in having met its design specification in full (it has actually exceeded its rated power of 300kW and consistently exceeded its rotor design efficiency) as well as having remained operable in open sea exposed conditions for almost three years.


The commercial prototype known as "Seagen" is presently under construction and due for installation in Strangford Narrows, Northern Ireland in the late summer of 2006. The design process has been validated by the leading marine classification agency, DNV (Det Norsk Veritas) with a view to developing and obtaining type approval for the MCT Seagen turbine system.
The Seagen twin rotor turbines, rated at approximately 1MW (megawatt), incorporate a patented system for raising the rotors and power train above the surface of the sea for ease of maintenance. It is hoped that the first commercial demonstration array will be installed by the end of 2008. MCT is also exploring opportunities for demonstration projects in other parts of the world including North America and S E Asia in parallel with the first UK commercial array. MCT also has plans for more advanced "Second Generation" technology which can be scaled to higher (or lower) power levels than Seagen and applied in a greater range of flow conditions.

MCT is dedicated solely to the development of commercially viable marine current turbines and has a number of commercial strategic partners and shareholders, including EDF Energy, Guernsey Electricity, BankInvest, Seacore and Bendalls Engineering.The Seaflow project was financially supported by the UK DTI (Department of Trade and Industry) and the European Commission and Seagen is also being supported by the DTI.

For more information go to: www.marineturbines.com or http://www.bwea.com/marine/devices.html

Notes:

The kilowatt (symbol: KW) is a unit for measuring power equal to one thousand watts. Or enough to electricity to power 50 x 20 watt low energy light bulbs.

The megawatt (symbol: MW) is a unit for measuring power equal to one million watts. Or enough to electricity to power 50 thousand x 20 watt low energy light bulbs.

Energy Generation: Stingray Tidal Power & Frond Wave Power

The Engineering Business (EB) started investigating renewables as a potential third market, behind submarine telecom and offshore oil and gas, in 1997 and comments that it soon became clear that Renewable Offshore Power Generation would be the most attractive technology area given the experience and expertise of EB staff. The devices currently being developed include both tidal and wave energy technologies, dominated by the 'Stingray' tidal generator and the 'EB Frond' wave energy converter.

Stingray uses the flow of the tidal stream over a hydroplane to create an oscillating motion that operates hydraulic cylinders to drive a motor that, in turn, drives an electrical generator. This device is a seabed mounted machine, to be situated typically in any water depth up to 100m.

The EB Frond, on the other hand, is a seabed mounted nearshore wave energy device designed for installation in 20-35 metres of water. A paddle-like collector on the end of a long lever is placed close to the sea surface and driven by the waves to produce hydraulic power similar to that of the Stingray.

In September 2002 EB tested the Stingray generator offshore in the Yell Sound off the Shetland Islands in the Highlands. The 180 tonne, 150 kW machine was installed and removed safely and data collected for analysis to aid the further development of both the demonstrator and commercial units. The 3rd phase of the development programme, a reinstallation of the demonstrator in the Yell Sound, has also been completed in 2003 and included a more flexible control system to allow the performance of the generator to be accurately controlled and recorded over a longer period.

The EB Frond is not at such an advanced stage of development but the phase 1 physical testing has been undertaken at scales of 1/33rd and 1/25th in the Lancaster University test tank, the academic partners in the project. Phase 2 is proposed for development in which a larger model will be deployed in more varied and extreme wave conditions. EB state that if this is successful it should lead to the design, build and installation of a full-scale demonstrator in a real near-shore wave environment, possibly as early as this year.

Future plans for the Stingray include a 5MW pre-commercial Stingray farm to be connected to a local power distribution system in order to test an innovative system for smoothing the flow of electricity from the oscillating devices.

For more information go to: www.engb.com or http://www.bwea.com/marine/devices.html

Notes:

The megawatt (symbol: MW) is a unit for measuring power equal to one million watts. Or enough to electricity to power 50 thousand x 20 watt low energy light bulbs.

Energy Generation: Sperboy Wave Power

SPERBOY™, developed and patented by Embley Energy, is a floating wave energy converter based on the 'oscillating water column' principle. Air displaced by the oscillating water column is passed through rectifying turbine-generators. Designed to be deployed in large arrays 8 to 12 miles off shore providing large-scale energy generation at a competitive cost.

With a minimum number of moving parts, which are above the surface of the sea, maintenance requirements are minimised and energy is produced at a very competitive rate. Current research is looking to extend the life of the vessel to some 50 years and includes several initiatives to deliver higher levels of power. Consequently the device has considerable potential for further reducing the cost of delivered power.

The absence of large quantities of invasive products such as oils and lubricants coupled with minimal impact on seabed ecosystems makes the device environmentally friendly.

SPERBOY™ has completed the Marine Energy Challenge, where independent consultants investigated its performance in terms of power capture as well as carrying out a detailed study of both capital and maintenance costings in arriving at their prediction for the cost of delivered power. The device is now ready to exploit the very successful and encouraging results of this 'Challenge' and will now proceed to the deployment of full-scale prototypes.

For further information see www.sperboy.com or http://www.bwea.com/marine/devices.html

Pelamis Wave Power

Ocean waves represent a considerable renewable energy resource. Waves are generated by the wind as it blows across the ocean surface. They travel great distances without significant losses and so act as an efficient energy transport mechanism. Waves generated by a storm in mid-Atlantic will travel all the way to the coast of Europe without significant loss of energy.

All of the energy is concentrated near the water surface. This makes wave power a highly concentrated energy source with much smaller hourly and day-to-day variations than other renewable resources such as wind or solar. Conveniently, the seasonal variation of wave power closely follows the trend for electricity consumption in Western Europe.

The western seaboard of Europe offers an enormous number of potential sites. The most promising sites are off the UK, Ireland, France, Spain, Portugal and Norway. There is sufficient energy breaking on the UK shoreline to power the country three times over.  However, it is not practical to recover all of this energy. The economically recoverable resource for the UK alone has been estimated to be 87TWh (terawatt hours) per year, or about 25% of current UK demand.

OPD was established at the beginning of 1998 by Dr Richard Yemm to develop the Pelamis Wave Energy Converter. This device is known as a 'point absorber' and can effectively focus energy from a wide area by interacting with an area of waves much larger than its physical size. As it is flexibly moored it swings head-on to the incoming waves and can therefore span successive wave crests.

The Pelamis is a semi-submerged, articulated structure composed of cylindrical sections linked by hinged joints. The wave-induced motion of these joints is resisted by hydraulic rams, which pump high-pressure oil through hydraulic motors via smoothing accumulators. The hydraulic motors drive electrical generators to produce electricity. Power from all the joints is fed down a single umbilical cable to a junction on the sea bed. Several devices can be connected together and linked to shore through a single seabed cable.

Following six years of detailed design and development, OPD has completed the build of the first full-scale Pelamis Wave Energy Converter. The 750kW machine measures 120m long by 3.5m wide (about the size of four train carriages) and weighs 750 tonnes fully ballasted. In August 2004 Pelamis was connected to the UK gird at the European Marine Energy Centre (EMEC) in Orkney to be tested. This is the first offshore wave energy to be exported into the UK electricity system.

For more information go to: http://www.oceanpd.com/ or http://www.bwea.com/marine/devices.html