Totnes Weir Archimedean Screw hydropower turbines and fish pass

The Totnes Weir hydropower scheme was developed by Dart Renewables and when completed it is estimated that the two Archimedean Screw hydropower turbines rated at 150kW each will generate 1,200 MWh of renewable energy every year, enough to power the equivalent of around 400 homes and saving 500 tonnes of C02. It is expected that around two thirds of the electricity generated will be used to power King Edward VI Community College, which serves around 1,700 students, and Atmos Totnes, a community development involving the construction of 60 to 70 social housing units and housing for older people.

Totnes Weir

The environment

Numbers of migratory salmon and sea trout are in decline in the river Dart, in part due to difficulty in passing the Totnes weir. The species are currently being held at the weir, where seals predate, leading to mortality of the fish. The construction of the Totnes Weir scheme will include the installation of a modern fish pass which allows the fish to pass the weir and continue their journey upstream to spawn. It is expected that this will reduce salmon and sea trout losses in the river Dart and over time increase the population of these species in the river Dart catchment. The scheme would also encompass an additional Larinier type fish pass, alongside the repair of the existing pool-and-traverse fish pass. Underwater cameras and a fish counter will estimate Salmon and Trout migration to spawning grounds in the Upper Dart. This will provide valuable data on the species in the river Dart which will be shared with both the Dart Angling Association and the Environment Agency.

Totnes Weir

Totnes Weir

Community benefits

Dart Renewables developed the Totnes Weir scheme in close conjunction with the local community in Totnes and the scheme will benefit the community in a variety of ways. Around two thirds of the power generated by the Totnes weir scheme will be used to power the local school in Totnes, King Edward VI Community College (KEVICC), and a community development of affordable homes and community facilities for the Totnes area which is being managed by the Totnes Community Development Society (TCDS). Electricity will be sold to these organisations at a mutually beneficial rate compared to prevailing market rate.

The Environment Agency, the Dart Angling Association, the TCDS and TRESOC (the Totnes Community Energy Society) have been closely involved in the consultation process for the Totnes Weir scheme and are very supportive of the project. A small classroom complex is proposed for the site next to the weir to be used by a KEVICC educational trust.

 

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Larinier fish pass

Fishtek were responsible for the design of the new Larinier fish pass and the improvements and modifications to the existing fish pass on the far side of the river from the hydropower scheme. A few images of the turbines and fish pass are shown below.

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The fish pass can be seen in the images above (running at a very high level as the turbines were temporarily turned off when these images were taken). A fish counter is to be added at the upstream end of the fish pass very shortly and this will provide invaluable data for the ongoing monitoring of fish populations in the river.

Funding

Triodos Bank helped Dart Renewables raise the £1.3 million needed to build the hydro power scheme through a Bond Issue. Local investors were offered the opportunity to invest a minimum of £2,000, with the minimum for those living further than 15 miles from Totnes being £10,000.  Investors could earn up to 8% return a year for up to 8 years.

Once again we see the Ancient power of Archimedes being used for hydropower generation because if it’s fish-friendly credentials. The Archimedean Screw turbine provides a fish-friendly alternative to conventional turbines, ideally suited to low-head (1m-10m) sites, and sites with fish protection issues. Extensive fish passage tests have conclusively demonstrated that the large water chambers and slow rotation of the Archimedean Screw allow fish of all sizes, and debris, safe passage through the turbine. As a result, the Environment Agency has agreed that no screening is required.

If you are the owner of an old mill site or a potential hydro site or are a community group interested in developing a hydro project for community use please contact us here.

 

 

Clean, green hydropower at Gara Bridge, Devon

The Archimedean Screw hydropower turbine is a new application of an ancient technology. For thousands of years the screw was used to pump water up from rivers or streams to irrigate farm land. Now, using the same system in reverse the Archimedean Screw is being used to harness the power of the water to generate hydroelectricity. This technology lets you harness the power of the water that flows over or through your land. Once it has been hooked-up your turbine will generate hydro-electric power 24 hours a day, seven days a week.

Whether the power is for your own property, to sell back to the grid or a combination of both, the Archimedean Screw will likely pay for itself several times over in the course of its operational lifetime. And what’s more these turbines can be scaled to suit all needs – from small domestic applications like the Gara Bridge scheme or to huge industrial installations like the hydropower project at Shane’s Castle. The hydro project at Shane’s Castle was the first of its kind in Northern Ireland and rated at 214 kilowatts it is the largest single Archimedean Screw generator ever manufactured.

hydro 5 (800x600)The hydropower scheme at Gara Bridge was developed to provide a renewable source of power to a private dwelling with any excess sold to the National Grid. The maximum output of this particular project is 15kW. The enclosed compact design which is suitable for smaller hydropower projects was the preferred design of screw for this particular site and the design also helped to minimise the installation cost.

Closed Compact –  Key Benefits:

  • Screw + trough + gearbox + generator are all assembled into a single unit at the factory.
  • Civil works on site reduced to a minimum.
  • Installation time considerably reduced (approx 3-4 hours)

Archimedean Screw turbines offer a uniquely flexible hydropower solution that can be installed at sites with a broad range of topographical features. But there are some fundamental requirements your land will need if a project can go ahead. If you’re not sure whether your site is suitable for an Archimedean Screw we’ve put together a checklist of requirements for your reference.

Naturally we will conduct a detailed feasibility study on your behalf but there are a few key features whose presence will determine the location’s viability for a Screw.

The basic requirements to host a screw are:

  • A water source with a drop of at least 1.5 metres
  • Access rights to that water source
  • A grid hook-up point less than 500 metres from the water source – unless the Screw is being used for ‘off grid’ generation only.

If your site satisfies these criteria then there’s every chance you will be able to harness the power of the waterway to generate hydroelectricity.

To keep up to date with what’s happening in the world of hydropower  follow us on Facebook or Twitter and  Google+ . To talk to one of our engineers contact us here

 

 

Fish-friendly hydropower at Sowton Weir

Sowton Mill stands on the  River Teign in Devon and has been using hydro power for over 400 years, initially to mill corn and then, from the 1950s, to generate electricity.  In the 1980s a 16kW crossflow turbine was installed which was the U.K.s smallest electricity contributor to the National Grid. To improve the power generation and aid fish migration a decision was made to install the fish-friendly Archimedean Screw hydro turbine. Sowton hydropower scheme was developed by a private client to provide a renewable source of electricity to the property on site with all excess power sold to the National Grid.

95kW Archimedean Screw Hydro turbine

95kW Archimedean Screw Hydropower turbine

Mann Power Consulting Ltd.,designed the Open Compact Archimedean Screw for this particular site which was manufactured by Landustrie in Holland.  An Open Compact is a self-supporting U-shaped steel construction minimising necessary civil work on site. The generator unit is an integral part of the construction, easily accessible via a weatherproof, hinged generator cover. The length and diameter of an Archimedean Screw will be dictated by the parameters of the particular site and are finished in the colour of your choice. All Archimedean Screws are manufactured as bespoke installations. Rated at 95kW it is expected to save in excess of 165 tonnes of Carbon Dioxide (C02) annually. The predicted annual output is 368,000kWh per year.

Fish-friendly hydropower at Sowton Weir

Closed compact Archimedean Screw

Improvements were also made to the fish pass at the nearby Weir.  These measures will make it easier for fish to move upstream and will add to the understanding of their migration patterns. The Archimedes  hydropower installation has improved the fisheries ecology of the river Teign by allowing more juvenile salmon and sea trout reach the sea. The improved fish pass at the weir means more salmon and sea trout can reach spawning grounds on the upper Teign. An automatic fish counter was also installed to count the fish numbers and species using the pass. This provides invaluable information for the Environment Agency and the Teign fishing association.

Sowton Weir

Sowton Weir

Once again we see the Ancient power of Archimedes being used for hydropower generation because if it’s fish-friendly credentials. The Archimedean Screw turbine provides a fish-friendly alternative to conventional turbines, ideally suited to low-head (1m-10m) sites, and sites with fish protection issues. Extensive fish passage tests have conclusively demonstrated that the large water chambers and slow rotation of the Archimedean Screw allow fish of all sizes, and debris, safe passage through the turbine. As a result, the Environment Agency has agreed that no screening is required.

If you are the owner of an old mill site or a potential hydro site or are a community group interested in developing a hydro project for community use please contact us here.

It’s True! The Archimedean Screw is Fish-friendly.

Archimedean Screws are the preferred hydro-turbine for the development of low head sites. They provides a fish-friendly alternative to conventional turbines and sites with fish protection issues.

As a renewable energy company that cares about environment we have done our research on all our products before taking them on board and are happy with the test results proving that the Archimedean Screw is in fact fish-friendly.

Fyke Net at oveflow

Fyke Net at oveflow

Fish Passage Testing:

Extensive fish passage tests have conclusively demonstrated that the large water chambers and slow rotation of the Archimedean Screw allow fish of all sizes, and debris safe passage through the turbine. As a result, the Environment Agency has agreed that no screening is required. Literally thousands of fish passages have been monitored and recorded using underwater cameras at the intake, inside the chamber of the Screw itself and at the outflow to assess the effect of the Screw on salmonids (including smolts and kelts), brown trout and eels.

Salmon smolt caught passing naturally downstream through the turbine

Salmon smolt caught passing naturally downstream through the turbine

Fish Passage Test Results Phase 1

Fish Passage Test Results Phase 2

Fish Passage Test results Phase 3

73cm Pike after passing through the turbine

73cm Pike after passing through the turbine

The trials looked at fish passage across a broad spectrum of sizes and turbine speeds, possibly the most impressive of which was the safe passage of a kelt measuring 98cm in length and weighing 7.6kg. In addition, behavioural and migrational patterns across the species have been shown to be entirely unaffected by the turbine. The implication of these findings is extremely positive for the economics of micro-hydro. Sites previously written off for hydro development owing to fish protection issues can be revisited, and the cost of installation for an Archimedean Screw turbine will be significantly reduced by the requirement for only minimal screening.

New recommendations in place for the UK:

Although over 100 screw turbine systems are currently operational on the continent, with no reported fisheries issues or problems, in the UK recommendations are in place to reduce the risk of Archimedean Screws even further.

Rubber bumper on leading edge of the Archimedean Screw

Rubber bumper on leading edge of turbine blade

Work by Fishtek Consulting  on risk of injury should a fish be struck by the leading edge of a turbine led to the recommendation that in order to minimise the risk of injury, the leading edges of small Archimedean Screws under 2.5m in diameter should be fitted with rubber bumpers and larger turbines with fish friendly compressible bumpers to mitigate the effects of higher inpact speeds on the largest screw turbines in use. These bumpers are now required as standard on larger Archimedean Screws.

For full report see: Archimedean Screw Risk Assessment: Strike and delay Probabilities

Rubber bumper attached to leading edge of the Archimedean Screw

Rubber bumper attached to leading edge of turbine blade

 

Photographs copyright  Fishtek and Mannpower Consulting Ltd.,

Please Note: All the reports are copyright and may not be used for commercial purposes without the prior consent of Mannpower Consulting Ltd.

 

Bealey’s Weir Hydropower

The Bealey family arrived in Radcliffe in 1732, operating as whitsters (bleachers) from a factory in Drumers Lane and used bleach fields close to the parish church of St. Mary’s, next to the river Irwell. Although the Drumers Lane site was close to the river, it was above the river level. The bleach works used large quantities of water for both processing and power (Bealey’s had eight water wheels in 1794) so they built a weir in 1811 further upstream on the Irwell to provide a constant head of water with long feeder or millrace.

A channel known as Bealey’s goit  was dug to carry the water the 1.4 miles (2¼ kilometres) to the factory and this can be seen today along with a Sluice Gate that is situated between the river and the Goit.

The Sluice Gate that is situated between the river and the Goit.

An Archimedean Screw Hydro turbine has been installed, commissioned and is now generating electricity at Bealey’s Weir.  An Open Compact Archimedean Screw was designed for this project. An Open Compact is a self-supporting U-shaped steel construction minimising necessary civil work on site. The generator unit is an integral part of the construction, easily accessible via a weatherproof, hinged generator cover.

The length and diameter of an Archimedean Screw will be dictated by the parameters of the particular site and are finished in the colour of your choice. All Archimedean Screws are manufactured as bespoke installations.

Open Compact Archimedean Screw

Rated at 96 kilowatts this hydro turbine is predicted to save in excess of 205 tonnes of Carbon Dioxide (CO2) annually. It measures 2500mm in diameter with a length of 14m. The site has a head of 4.62m, capacity of 2910l/s and the rotation speed is 27.5rpm.

Bealey’s Weir

Mann Power Consulting Ltd., the UK based Archimedean Screw specialists designed the equipment for this project.  It  was manufactured by Landustrie based in Holland and Eco Evolution were involvd in the commissioning of the project with Mann Power Consulting.

Archimedean Screw Hydro Turbine in situ

Archimedean Screw Hydro Turbine

In comparison with most turbines the Archimedean hydropower screw makes use of an open construction and a low rotational speed. This results in a natural flow and there is no pressure build up in the entire installation. Furthermore extensive testing shows that due to the size of water chambers and the fact that there is no pressure difference fish will pass through unharmed.

The Landy hydropower screw makes use of a specially designed inlet and outlet that make the screw absolutely fish friendly. The water outlet is designed in such a way for the water (and fish) to smoothly exit the screw without splashing. This also reduces the noise that water creates.

All photographs copyright of  Eco Evolution.