WHEN MARTIN LEAHY decided to put the mill back into “Millstream”, the name of the townland outside Abbeyfeale in Co Limerick where his family farm is situated, he did not envisage the mountain of paperwork involved nor the innovative design that would go into the building of a modern hydroelectric station.

Four years on, a project originally conceived to provide power for domestic purposes is now sold directly into the grid, replacing the flax mill from which the area takes its name. The station was designed using nine 10ft by 20ft pre-cast concrete box culverts in a building block-type construction. Two of them together form the generating room.

These culverts, usually used in motorway construction, cost a fraction of what Leahy – professor of physics at the University of Limerick – would have paid for a single concrete construction.

“Originally, when I designed it, the idea was to build the walls with mass concrete up 10m. But it very quickly became clear that if you were going to do it in one pour, the pressure at the bottom would be extraordinarily high, making the whole thing very expensive to do. So, the cheapest cost I was quoted for that was €75,000, just for the concrete works.

The culverts were cast on site in Banagher Concrete for €21,000 and delivered onto site and dropped into place in one afternoon using a 100-tonne crane.”

The entire project cost around €120,000, a price Leahy believes is a fraction of what it would have been if he had contracted out the design and construction to other parties.

“The design and paperwork would have cost a multiple of that. One of the difficulties with hydro is that it is far more complicated than wind, in the sense that for every site, it is different.

His farm, he says, had a field that he “got sick of draining” and after he excavated a 500m headrace that diverted water from the River Allaughan, and a 300m tailrace that allows the water to re-join the river, the field became a two-acre reservoir. In total, an 8.5-metre drop in the water from where it enters to headrace to the turbine makes for enough power for the energy needs of 90 homes.

“Originally, the idea was to feed the farm and my own house. And then when I looked at the resources, there was significantly more than that,” he says.

The big advantage his hydro station offers over wind is that he can store his water, up to 55,000 tonnes, which is, in effect, pent-up electricity.

“I am able to store eight hours of the maximum amount of electricity, which has two effects: It means that when I do not have enough water to supply the thing full-time all day long, I can store up the water, and I can sell it at the highest tariff, during the day instead of selling it at night,” he says.

Secondly, during periods of very low rainfall, he can turn off his turbine altogether rather than run it at a damaging low speed, storing the water until there is enough to run the turbine for a day. At full capacity, however, it handles 1.4 tonnes of water per second.

He has been generating electricity for the past four years. But even though the construction phase lasted just 12 months, his original planning permission was granted as long ago as 1999. Overall, the paperwork was a 10-year process, one he characterises as “everything you have to do for wind farms” plus dealing with the fisheries board.

This includes county council planning permission, approval from the fisheries board, licences to construct and generate from the Commission for Energy, winning a competition to sell electricity from the Department of Energy, a supply contract from ESB Customer Supply and a grid connection from ESB Networks.

“It should not require as much effort to put together a small hydro project as it does a 100 megawatt or a €200 million wind project – or even a €20 million wind project. I have done both and I can say the hydro one has more paperwork, which does not seem logical.”

He also got a grant from Sustainable Energy Ireland and, as part of its terms, he shows the station to interested students, including those from UL doing a BSc in Energy, a course the project helped inspire.

Apart from its culvert design and ability to effectively store electricity, the project also led to the development of a computer programme to identify pumped hydro storage sites as well as a patent for direct interconnection of renewable generators.

“The whole experience of having to go through the design and doing this hands-on I found much more beneficial for the educational experience – that I had to learn to do all of the civil engineering, the electrical stuff, the environmental assessment and interacting with contracts and all those sorts of things,” he says.

Despite hydro’s advantages, be believes a national renewable energy strategy should refocus on wind because it is so easily harnessed. It offers a way of reducing the State’s dependency on imported fossil fuels – and their €6 billion annual cost – and a means of stabilising energy prices.

Under Ireland’s current energy policy, it is very exposed to changes in the oil price, “which can easily go up by 50 per cent in response to a skirmish in Libya,” says Leahy.

“The exposure to that is huge and the impact that has on industry,” he says. “If you could promise Intel that the energy prices are going to stay on a particular track – just normal index linking for the next 15 years if they are going to be investing maybe €10 billion in a new plant. They are going to want to know that sort of thing, because they use a lot of electricity.”

The government target is for 37 per cent of electricity to be generated by wind by 2020, up from the current 15 per cent. Leahy says there should be big investment in the grid system to enable connection of new energy projects quickly and cheaply. Currently Ireland has a total installed electricity capacity of 6,700 megawatts (MW), of which 1,425 MW comes from wind.

According to Eirgrid, there is a total of 3,900 MW of connection offers being issued to wind farms as part of the current process, and a further 12,000 MW of wind farms have applied for connection outside of this. Leahy says this kind of capacity, once connected, could produce 80 per cent of Ireland’s needs by 2020 if storage facilities were also in place. However, that this will not happen without a massive shift in ESB, Eirgrid and government policy and a “fundamental change to planning for connections”.

“If you had planning permission today for a 100 MW wind farm and you could displace a huge amount of imported fossil fuels, you would have to wait at least until 2023 to connect that from the current scheme,” he says.

Apart from the wait, the current regime is structured so that new entrants pay the connection cost, one which can be up to 40 per cent of a total project cost.

“Unlike in other countries, in Ireland, all of that cost is lumped onto the developer. It is not considered a grid service. Even for this project, that was €26,000.

“Essentially, the Irish system is not government-supported at all. There is a theoretical support which provides a floor under the price at about seven cent a unit,” Leahy notes.

Tapping into Ireland’s wind capacity would also require large investment in energy storage facilities, such as electric cars, which could store cheaper night-time wind energy and allow the owners to sell it back to the grid during the day.

“Once the renewable fraction of the Irish electricity generation portfolio becomes greater than 40 per cent, storage is vital. Internationally, storage is the key enabling technology for the integration of renewable energy.”