Hydropower mills may bridge gap

HARD to believe it nowadays, but Ireland had more than 6,000 watermills in the middle of the 19th century.

We are, however, seeing a low key resurgence in small hydro stations to generate electricity for households, businesses, or hotels.

Only 6% of the country’s energy is generated from the power of water, largely through the bigger stations. The ESB hydro station at Ardnacrusha, Co Clare, built in the 1920s, is still our largest renewable energy generating unit. So clearly, given our abundance of free flowing water, there’s huge potential for harnessing rivers and streams — an unexploited resource.

Experts tell us the amount of power generated by small stations can at least double to more than 60MW. The Irish Hydropower Association estimates, for example, that up to 600 old mill sites around the country could be redeveloped into hydropower generation sites.

The previous Minister for Communications, Energy and Natural Resources, Eamon Ryan, introduced incentives, including a guaranteed price of 19 cent per kilowatt hour of electricity produced by micro power plants. The payment for surplus electricity will apply to the first 4,000 micro-generation installations countrywide over a three-year period. Grants are also available.

Water has been among the chief sources of power for at least 500 years. By 1850, Ireland had around 6,400 watermills, according to the EU-funded SPLASH (Spatial Plans and Local Arrangement for Small Hydro) report.

Water wheels were eventually replaced by turbines and expanding industry came to be served by national and regional power grids. Small hydro sites were abandoned, but now there is renewed interest in the small sector.

As well as their obvious usefulness, something strongly in favour of the small sites is that they have far less impact on the environment the bigger ones. They usually do not require new dams, or reservoirs, and their construction can also allow for the passage of migratory fish.

Nearly all of the old watermills have long since fallen into disuse, but the potential they represent is still there. Cost is a factor, but the report emphasises that small hydro schemes are a secure and reliable form of energy that should be used as part of the drive to promote renewable energy.

As its contribution to the SPLASH project, the Cork County Energy Office came up with a local plan for the River Blackwater. Many of the locations identified in the plan are existing sites, or sites noted in previous studies.

As might be expected, concerns have been raised by heritage and angling interests wary of development, all of which comes down that eternal issue — balancing energy generation with the protection of the river.

One of the big problems, according to the report, is that the hydro scene in Co Cork is viewed against a background of the large Lee Valley scheme, which flood a huge amount of land and which is generally seen as having a negative effect on the environment.

“The potential small hydro sites on the Blackwater have no parallel with this (Lee Valley) and are predominantly run-of-the-river sites with no new impoundment works, and limited or no impact on fisheries, provided suitable precautions are taken,” it goes on.

A successful small hydro scheme is operating at the 50-acre Coolwood Nature Reserve and Wildlife Park, outside Killarney, generating almost 7kw of power, or two-thirds of the facility’s energy needs. It involved a €15,000 investment, but should result in long-term savings.

Described as a hybrid between a water wheel and a turbine by the park’s founder, Sean Buckley, the site is made attractive by what looks like an old water wheel, which doesn’t collect debris or interfere with the passage of fish.

The so-called Buckley Water Wheel has been neatly installed in a stream running through the park and, like all hydro sites, has the added advantage of being reliably able to produce electricity when the need the need is greatest and water is most plentiful — in the winter months.

“Many towns in Ireland have disused mills and there’s no reason why they can’t be adapted again by using the system we have here. It’s a much more reliable system than a wind-powered system. Mills could be used to light a whole town. An old mill on the River Flesk once provided power for the town of Killarney,” Mr Buckley remarked.

Small hydro stations are commonplace in many countries. There are up to 500 such installations in northern Canada, for instance, serving hunting and fishing camps and cabins which have small streams nearby.

Up to now, the focus in Ireland has been largely on wind power. But, with both EU and government policies actively encouraging renewable energy sources, we could see more small hydro stations in the years ahead, even on ivy-clad sites that date from Victorian times.

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