Eco Evolution Blog

Turning the screw on power

Turning age old technology on its head has started to allow one Irish company to produce electricity from flowing water.

Ferns based company Eco Evolution (www.EcoEvolution.ie) has become the first in the country to commercialise the Rehart range of Archimedean screw hydro turbines.

Frank Gethings, managing director of Eco Evolution, said “Archimedean screws were traditionally used as water pumps to lift water from one level to another. Archimedean screw hydro turbines work in reverse. Water from a river or stream flows down the screw causing it to rotate. The screw is coupled to a generator via a gearbox and hence power is generated.”

Like many green energy companies they supply wind turbines and solar panels but are finding huge interest in hydropower.

The system can range from 1kW up to 130kW on a single screw system. The first large system of 120kW is to be installed in Omagh, Co. Tyrone, to provide electricity for a leisure centre.

The Archimedean screw is suited to low head sites and can cater for heads of between one and 10 metres height and can take flow rates ranging from 100 to 10,000 litres per second.

For larger flows, two or more screws can be used.

Frank said there is scope for installing it on farms but having an existing mill or works will greatly reduce the cost. It costs €20,000 for the equipment for the 1kW system, but additional site works have to be carried out. Cost efficiency is an issue of scale. A 300kW system might cost €1,000 per kWh to install but a 1kW system might be €20,000.

The system allows debris to flow through and has also been proven to be fish friendly.

“… It is a point echoed across the industry. ”The general trend for energy costs will be an upward one and there is also the advent of carbon taxes to consider,” says Frank Gethings, Managing Director of Eco Evolution in Ferns, Co. Wexford. His company offers a wide range of renewable solutions, with wind electricity generating equipment to the fore and a new line in hydro electricity products just becoming available. Gone are the days when these technologies were the preserve of immense ESB projects: They can now be incorporated seamlessly into many business premises.

“Water has been used for energy generation for centuries, but Archimedean screw hydro turbines are relatively new to the market – they’re a 21^st century application of an ancient technology,” says Gethings. “They are suitable for small domestic applications from 1kW up to larger applications of 350kW.” Both wind and hydro power work on simple principles: the rotor is turned by wind or water; a generator attached to the rotor then generates power that can be fed into the building’s power supply. Another renewable energy solution is solar power; a technology that has been around for years yet is only coming into affordable, mainstream usage now – particularly helping to reduce heating costs…”

When comparing solar panels efficiency is only part of the equation. You must also look at the aperture area of the panel. Some panels have a particularly low aperture area compared to the gross area of the panel. This means that the annual yield of such panels would be quite poor compared to panels with a similar efficiency but with a higher aperture/gross area percentage. Annual yield per square metre of actual physical panel is the best way to compare panels. With the poorer performing panels you would need more panels to give the same output as higher yielding panels, so for instance a 300L system may only require 2 x 12 tube panels of a high yielding panel versus say 40 or more tubes of a poor yielding panel. Unfortunately people sometimes think they are getting better value for money as they are getting more tubes, but in actual fact the annual yield may be lower than with a smaller number of the higher yielding panels. There can be a large variance between different panels as can be seen in the following comparison. All figures have been taken from independent test reports.

SolarEnergyComparison_Pdf