Ireland has a huge renewable energy resource that could help break our dependence on fossil fuels. This resource is far more reliable than the wind and provides a guaranteed supply of electric power. It is the tide.
Tidal flows, together with wave energy, offer enormous potential if technical challenges can be overcome and production costs reduced, argues Prof John Ringwood, dean of engineering at NUI Maynooth. "Ireland has the best wave climate in the world. There is no better place to tap into this resource." Tidal flows at selected locations along the east coast offer the best chance of tidal energy, he says.
They could provide the "base load" of guaranteed power while tides flow every day. The tide arrives at different times depending on location, so energy supply overlaps through the day.
When Prof Ringwood talks about wave energy, he is talking about ocean swell, not the waves that lap our beaches. South Korea is investing heavily in this technology using waves that deliver 10 kilowatts (kw) per metre of wave crest. Our west coast swell delivers an average 70kw per metre. "They are as good as off the notorious Cape Horn."
Technology already exists to harness this energy. One manufacturer, Pelamis, describes a wave farm with devices moored in water 50m deep and five to 10km from shore. A farm covering about a square kilometre could deliver 30 megawatts (mw), enough to power 20,000 homes. Twenty such farms could keep a city the size of Edinburgh in electricity, says Prof Ringwood.
Other, much larger, devices include the Wave Dragon, a tethered device that uses wide arms to channel water through a turbine. It claims outputs of between 7mw and 11mw.
The technology will have to develop further before it becomes fully economic, says Prof Ringwood. He believes Ireland should invest heavily to exploit wave resources and become a world leader in this technology, in the same way Denmark exploited wind energy and now supplies 60 per cent of the world's commercial turbines.
Dick Ahlstrom