a casestudy...Archimedes’ screw: CopleyHydropower GeneratorThe Archimedes’ screw – used for over 2000 years as a pump – is nowbecoming a popular technology choice for low-head hydropowergenerators. Future Energy Yorkshire (FEY) has carried out a study onthe relative costs of an Archimedes’ screw and the more commonKaplan turbine for a small scale hydropower site.

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BackgroundThe Archimedes’ screw is well suited to low-head sites andis reportedly less harmful to fish. A few dozen are in operationin Germany and the first examples are now appearing inthe UK. However, low-head hydropower is developing veryslowly in the UK despite there being thousands of potentialsites at river weirs across the country. It is often hard tojustify the capital expenditure of installing a modernhydropower scheme on such sites given the relatively lowrevenue from electricity sales, so this study compared thecapital costs of the two systems for a specific low-headhydro site.

Description of ProjectFEY commissioned a study to compare the costs of installinga Kaplan turbine and an Archimedes’ screw at the potential(and former) hydro site at Sterne Mill in Copley, near Halifax.One hydropower consultant was asked to design a systemusing the Archimedes’ screw while a second consultantwas asked to design a scheme with a similar annual energyoutput but using a Kaplan turbine. Each consultant wasalso asked to cost the equipment and its installation butexcluding the civil engineering costs. The two designs weregiven to an independent civil engineering firm whichcalculated cost estimates for the civil works.

ResultsThe two scheme designs did not arrive at exactly the sameannual energy output, but nevertheless the study showeda strong cost advantage for the Archimedes’ screw. For anenergy output of about 15% more, the Archimedes’ screwcost about 10% less. So in terms of capital cost in £ perMWh per year, the Archimedes’ screw was 22% cheaperthan the Kaplan turbine. The results are summarised in thetable below.

The study also demonstrated how much differentassumptions can affect the civil engineering costs. If thespoil from the construction had to be landfilled, for example,this would add from 30% to 40% to the costs above forboth schemes.

The costs for a hydro scheme are highly site dependentso it cannot be assumed that the Archimedes’ screw willalways be the cheaper option, but this study shows thatfor this site there is a significant cost advantage.

A full report of the results of this study will be published byFEY. It is hoped that a hydro system will be installed aspart of a major property development around the weir.

t 0113 237 8436e email@fey.org.uk www.fey.org.uk

If you would like more information on the Archimedes’ screwproject or how we can help your company please contact:

Jo Adlardjo.adlard@fey.org.ukDirect line: 0113 237 8426

OV1693

Annual energy outputInstalled capacityCapital costCapital cost (per MWh/yr)Return on investment(IRR, 20yrs)

Kaplanturbine

390 MWh95 kW

£414000£1061

5%

Archimedes’screw

448 MWh124 kW£371000

£8289%

So in terms of capital cost ...the Archimedes' screw was22% cheaper than the Kaplanturbine.

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