Eco Evolution Blog

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.

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.

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.

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.

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.

Energy generated from flowing water resources gives the highest efficiency rating of all sustainable energy sources!

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. Hydropower installations generate renewable energy from flowing water resources. This could be from a lake, river, stream or from old mill sites.

Archimedean Screw turbines offer a hydropower solution that is:

• Commercially attractive & cost effective
• Practical & efficient
• Fish-friendly
• Easy implementation in existing situations (no civil constuction work)
• Insensitive to clogging
• Low maintenance costs
• Improvement of water quality
• Self regulating to changing water flow
• Long life time
• Scaleable & bespoke

This technology lets you harness the power of the water that flows over or through your land. Once your turbine has been commissioned and connected to the grid you’ll be generating 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 (depending on the feed-in tariffs available) . And what’s more these turbines can be scaled to suit all needs – from small domestic applications to huge industrial installations.

Overview of an Archimedean Screw ~ Photo Credit: Landustrie

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. 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.

The basic requirements required for an Archimedean Screw hydro turbine 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. And Eco Evolution will be delighted to pilot your scheme all the way through to delivery.

If you’re still not sure whether your site is right for an Archimedean Screw turbine, get in touch and we will be happy to discuss the specifications and requirements in greater depth.

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.

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

The waterwheel is an ancient device that uses flowing or falling water to create power by means of a set of paddles or buckets mounted around a wheel. A waterwheel consists of a large wooden or metal wheel, with a number of paddles or buckets  arranged on the outside rim forming the driving surface. Most commonly, the wheel is mounted vertically on a horizontal axle. Prior uses of water wheels include milling flour in gristmills and grinding wood into pulp for paper making, but other uses include hammering wrought iron, machining, ore crushing and pounding fibre for use in the manufacture of cloth.

Traditional waterwheel

On occasion the old water wheel is still insitu and can be refurbished but in many cases the wheel has been removed and sadly sold for scrap metal value or taken apart to be kept as keepsakes or used as garden ornaments. If a mill has a vacant wheel pit it is possible to construct a water wheel which is aesthetically pleasing and bring the character back to the old mill. On some old mill sites access to the wheel pit is confined and in cases like this the preferred option is a bespoke laser cut waterwheel.

The spokes, rims and buckets are all fabricated from pre-galvanised sheet finished with polyester powder coating. These lightweight components were easily and rapidly assembled using stainless steel nuts and bolts without the need for welding or any special tools on site.

The waterwheel arrives flat packed on site and during construction, the waterwheel components can be lifted in place without the need for heavy lifting machinery, reducing installation time and health and safety risks. This also allows assembly in areas with limited access e.g. rural areas with narrow roads.

Advantages of waterwheels

Waterwheels are widely regarded as being rather inefficient compared with turbines. This is not necessarily the case as studies have shown that waterwheel efficiency can be in excess of 80% for Overshot waterwheels and 75% for Breast-shot waterwheels [Muller 2004]. This in combination with highly respectable part-flow performance and lack of fine intake screening requirements can often result in very worthwhile overall energy capture so are still a viable proposition for producing electricity for domestic purposes. They are simple to control and aesthetically pleasing. Although they run relatively slowly and require a high ratio gearbox to drive a generator, for low powers – say below 5kW – and heads below 3m, they are worth considering.

Water wheels are also safe for the passage of fish.

• Output reduction due to screen blockages is avoided since fine intake screens are not required.
• Part-flow performance of waterwheels can be very good without requiring complex control systems.
• Often minimal building work is required, particularly at former watermills if there is a vacant wheel pit.
• Waterwheels have obvious aesthetic benefits over turbines and provide an excellent attraction at sites where visitors are encouraged.

To keep up to date with our hydropower projects or to find out more about hydropower you can  find us on Facebook or Twitter and  Google+ . To talk to one of our engineers contact us hereWe offer a turnkey service if required and would be happy to discuss your requirements.

It’s been a few years now since the Archimedean screw hydropower turbine was installed and commissioned at Frensham Mill. However, I feel it gives a good insight into what can be achieved at old mill sites. You will see how the owners embraced hydropower and then made improvements to the landscape to increase the existing wildlife and natural habitat of the site.

Mill History:

Frensham Mill is an ancient mill site dating back to at least 1217 when the mill at ‘Feresham’ is mentioned in the Bishop of Winchester’s Rent Rolls. The mill had two mill ponds to ensure that the corn mill had a constant supply of water even if the main river supply ran low; one of which was built on a small Wey tributary carrying runoff from Frensham Great Pond. This large pond feeds into the Wey about half a mile above where the mill was located. The house was re-modelled in 1928 following the demolition of the old mill. At his time a Francis turbine was used to generate electricity. When the Mill was rebuilt in 1876 it was possibly the largest in SW Surrey. The oldest building, the Granary, was renovated in 2012 along with the gardens and the hydro/ heat pump project.

Frensham Mill during the Victorian era Photo Credit: Frensham Mill

The owners wanted to make the most of the renewable energy potential of the old mill race.  The solution was to combine an 11kW Archimedes screw hydropower turbine with a 30kW water source heat pump. Today the mill produces 70kWh of electricity per year and 90kWh of heat, saving over 50 tonnes of CO2 emissions per annum.

Installing the Archimedean Screw hydropower turbine      Photo credit: Mannpower Consulting Ltd

The Mill had been a barrier to migratory fish for hundreds of years. In order to improve migratory fish passage the Environment Agency specified a fish pass and upgraded stream to link upstream and downstream for the first time in hundreds of years to encourage trout, eels etc. The river banks were restored and the water meadow was reinstated with wild flowers. Around 10% of the river’s flow is directed down the fish pass and into an old ditch to provide a link between upstream and downstream. A series of 10 gravel pools were installed to step down the levels to the mill pond, providing areas of gravel as potential spawning areas.

Archimedean Screw commissioned and generating electricity Photo Credit: Mannpower Consulting Ltd

The green sand river banks had become severely eroded and were restored with an environmentally friendly planted coir roll system. With the environment utmost in their minds the owners decided to restore the river banks with this system designed to provide an enhanced aquatic habitat both above and below the waterline. Posts were driven into the river bed and pre-planted coir rolls were then placed on top of willow screening and back filled. Today the new banks have become very established.

River bank restoration at Frensham Mill         Photo Credit: Frensham Mill

A survey of the site also found evidence of Serotine & Brown Long Eared bats.  A light proofed area and improved access tiles were installed in the main roof as part of requirements to enhance their habitat. A survey found an established badger trail along the eastern boundary of the site ( that was left undisturbed by the works). Water voles and kingfishers have also been spotted on site.

Completed hydropower project                   Photo Credit: Mannpower Consulting Ltd

And the Archimedean  screw is now set in a garden intended to reflect the spiralling curves of the screw. The water meadow is in the process of restoration with a plan to plant over one acre of wild flowers.

Archimedes set in the garden designed to reflect the screw spirals   Photo Credit: Frensham Mill

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.

To keep up to date with our hydropower projects or to find out more about hydropower you can  find us on Facebook or Twitter or Google+ . To talk to one of our engineers contact us here