Lowestoft company harnesses the power of the tide to produce energy

Tests have revealed that a device which harnesses the power of tidal waves to generate energy will produce 25 pc more power than originally predicted.

Developers of the Tidal Harvester 2 (TH2), a machine that could one day be used in the North Sea and linked in to the National Grid network, are celebrating success.

Invented by East Anglian research and design firm 4NRG, a prototype harvester was tested on Lake Lothing in Lowestoft last month. The trial was designed to establish how much energy a full scale device could generate.

Having analysed the results, scientists and engineers involved have now claimed the harvester has exceeded expectations.

'We just don't really realise how much power is in moving water,' said Dave Watson, managing director of 4NRG.

'This bodes very well for our other tidal devices derived from the TH2 design.'

The Lowestoft-based company wants to see tidal harvesters working around wind farms off the East coast.

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It is also looking at putting a modified version, currently known as Tidal Harvester 5, on the River Yare at Great Yarmouth. That device would act as flood defence as well as an energy generator.

The developers behind the simple but sector-leading harvester also believe that a series of linked 'near-shore' devices which absorb energy from waves and tides could go a long way to protecting the coastline from erosion.

'Hopefully successfully proving that the device works at this scale will lead us one step closer to placing commercial scale Tidal Harvesters in the North Sea in the near future,' added Katie Musgrove, a senior researcher at 4NRG.

The harvester works by allowing the tide to pass through it, pushing blades to generate power. While the prototype made by Lowestoft shipping company Small & Co was seven-metres long and weighed four-tonnes, a full size version would be 30 metres wide and substantially heavier.

The key findings from the trial were that the prototype device started turning exactly at the water speed predicted, that it worked as expected at different speeds and, finally, that it generated energy when only 75 pc of the blade was submerged in the water.

The additional 25 pc of energy was generated during the test was due to the fact that previous calculations did not take into account that two blades enter the water at the same time.

Developers, who had consulted both Cranfield University and the University of East Anglia's mathematics department about the theoretical problem, were not sure if having a second blade would block the flow of water reaching the first.

However, repeated tests on Lake Lothing confirmed that no blocking occurred.

The aim is to eventually sell 1 megawatt devices at �3.5 million. Each would generate �1 million annually, have a break even time of four to five years, and a life of around 20 years.

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