Tidal-energy demonstrator deployed in estuary
Humber rides the wave
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A full-scale demonstrator of what is claimed to be the first tidal-stream-energy device for estuaries is to be deployed in the Humber Estuary.
The £1m Neptune Proteus NP1000, from East Yorkshire-based Neptune Renewable Energy, will be completely constructed this month and commissioned shortly afterwards.
Jack Hardisty, technical director of Neptune, said that, once fully commercialised, there will no devices like it on the market.
‘We are not aware of any other device designed to capture the shallow-water resource,’ he said. ‘Proteus has a lightweight, exoskeletal structure designed to optimise estuarine locations where there are not the problems and stresses associated with wave activity but where, nevertheless, strong tidal regimes can be found. This produces very considerable build-cost benefits.’
The turbine is built with a distinctive square-turbine cross section, which Hardisty said generates 30 per cent more electricity per unit channel width compared to circular turbines.
‘The capture area of a square is about 30 per cent greater than the capture area of a circle that has the same diameter as the side length of the square -technically it is 4/pi,’ he said.
The Proteus is also designed with patented flow-control shutters to maximise the area of water hitting the turbines, thus increasing torque and power output.
Hardisty said the flow-control shutters help maintain tip-speed ratio -the ratio of the tip speed to the fluid speed - and that effects the turbine’s overall efficiency.
‘For the vertical axis, crossflow rotors on Proteus maximum efficiencies are achieved at a tip-speed ratio of 0.35,’ he said. ‘The computer-controlled shutters direct the flow at variable angles onto the blades in order to maintain this optimum tip-speed ratio, regardless of flow speed, and thus maximise the electrical output.’
Neptune Renewable Energy stated that the Humber Estuary was selected for the first deployment of Proteus as, given its depth and tidal flow, it is considered one of the best locations in the British Isles for tidal-stream power.
It is estimated that, once in situ, the Proteus should generate at least 1,000MWh/year.
Neptune Renewable Energy claims that the Proteus will have minimal impact on the environment because it is a moored system. Also, the bulk of its mainly steel construction can be recycled once decommissioned.
Readers' comments (10)
Andy Taylor | 12 Jan 2010 11:18 am
Great! Let's have them in the rivers too. All that free power and we're not using it. They do in France!
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David Cutter | 14 Jan 2010 9:00 am
For rivers and streams there is the Archimedian screw, a working example of which is installed at Howden Mill near York. This provides 25kW to the grid from a modest site.
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Peter Field | 14 Jan 2010 9:44 am
There is no such thing as free power. As with all the other numerous renewables projects reported in The Engineer, we need to evaluate performance, load factor and return on investment. This is never forthcoming. The figures imply an income of about £30,000 per year at say 3p a kWh which seems fair, if the energy is free. For a one million pound price, plus say 20% for civil and electrical work, the pay-back period is 40 years! Not a normal marketable investment. The only way out is for the tax payer and energy user to subsidise such activity by means of the ever growing list of subsidies such as The Renewables Obligation; feed-in tariffs etc etc. Soon the country will be bankrupt.
However, lets see full performance data so we can, as engineers evaluate.
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Nigel Shipley | 15 Jan 2010 1:49 pm
As previously stated by others, this is not overly convincing. Questions like:
How many MW is consumed in the UK per year and this would equate to how many generation units placed on every tiday flow point of the UK ?
How many locations can we place such generating devices on ?
At what point do we say NO its not going to provide effective power production against the total cost of each unit ?
If, for example, someone was able to develop a device that would convert free energy to electricity and maintain the sort of output that a nuclear power station can produce, then the investment would be worthwhile. For now, generating enough power to run a small housing estate is relatively insignificant. Power for an average city would be good but the estuarine locations would be over filled with generating devices and would prevent marine traffic using the areas.
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martin doxey | 15 Jan 2010 2:04 pm
The Humber gets a lot of trees and branches coming down from the Trent and Ouse and it is dark brown with all the sand and mud that is stired into it by strong tides. I predict that the wood debris will jam it up and when that issue is solved that the slower flow rate resulting from the device will cause a build up of sediment that blocks the flow. I hope I am wrong but let's see!!
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Peter T | 16 Jan 2010 0:35 am
I am pretty pro-nuclear and have been since my university days. Nigel rightly raises the question of whether this tidal technology is cost effective, much as it grieves me to say so nuclear would not be considered cost effective using the criteria that defeats the tidal technology. The recent cold period however has highlighted this country's energy vulnerability when we are so dependant on foreign gas and also it must be noted foreign coal and uranium too. This technology - like wind or wave power - will not solve our energy problems but it will distribute the risk to an extent. This country has always suffered with short termism. Peter is right, a 40 year payback period is not very attractive to financial institutions in this country, a lot of them seem almost to be day traders. Countries like Germany have a much longer term view of things. Fusion power is the ultimate solution, but you are unlikely to see a return on any investment in this technology any time soon. The human perception of time is closely linked to our lifespan. If the human race is to survive it needs to take a much longer view of things and accept that some things may not be justifiable on purely economic grounds but will be of overall benefit.
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Chris Knight | 18 Jan 2010 5:20 pm
The NREL website says "NREL has developed and cost engineered the innovative Neptune Proteus NP1000, to achieve a target capital cost of less than £1m/MW."
What does £1M/MW mean? Is this peak power or average power? Or do they really mean MWh/yr?
They also claim that tidal power is "continuous and not intermittent". Every tide that I have seen stops at least twice per day even if only for a short period.
Does the £1M include any maintenance and running costs? If not, I can't see that this will ever cover it's costs. However this does depend on what happens to the cost of electricity over the lifetime of the system, but there is no indication of what the expected lifetime is.
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John Fulcher | 1 Mar 2010 2:17 pm
Nigel makes the same point as often used when renewable technology is advocated. The point is, no one is advocating mass installations of tidal turbines, for the very reason he puts forward, as no one (that I know of) thinks such as wind turbines en masse are the answer. But surely, varied sources of power as suitable must be a "good thing"? Again, not a mention as to actually saving energy. No single answer
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Anonymous | 1 May 2010 10:53 am
I'd quite like to know how much nuke, coal/gas/wind etc. cost/Mw to construct and run, buy way of direct comparison?
I'd also be curious to know why we would not have things of this general nature at sea, around our coast to reduce coastal errosion as a side-effect?
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malc | 16 Dec 2010 7:21 pm
I don't think monetary cost matters, if it works. That's the question that needs answering.
If it uses masses of carbon to build it, you can ask at what point it's "cost" neutral.
Why doesn't monetary cost matter? Same reason Mr A can buy a BMW when a tiny Renault would do if push came to shove.
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