Leading independent energy supplier Energia is continuing to strengthen its renewable energy portfolio, with its newest windfarm in the Republic, Caherdowney on the Cork/Kerry border, coming on-stream in April this year.
CIAN MOLLOY reports.
Energia, which is part of the Viridian Group, is perhaps best known in Ireland for its two combined-cycle gas turbines (CCGT) power plants at Huntstown in North Dublin, where the combined output of 747MW provides up to 20 per cent of the total electricity fed into the national transmission grid system. The company has also developed a strong reputation as a supplier of renewable energy, with its investment of more than €500m in Huntstown more than matched by its €550m plus investment in wind energy. Indeed, at this stage Energia currently has a 25 percent market share of the Irish wind-generation sector.
The latest of its wind assets is the €14m Caherdowney Windfarm , situated near Millstreet in Co. Cork, which comprises four 2.3MW Enercon E70 turbines giving a combined maximum export capacity of 9.2MW. The site was chosen due to its high average wind speeds, which are ‘Class 1’ rated. At full generating capacity, the windfarm is capable of powering around 6,100 homes or allowing for the varying wind conditions the wind farm can fully power an average of 1,900 homes every year.
The construction of Caherdowney illustrates the challenges of building this type of renewable infrastructure – not just the physical aspect, but the bureaucratic. Planning approval for the Caherdowney project was initially approved in 2003 but was held up due to lengthy delays in obtaining a connection to the electricity grid. Once such difficulties had been overcome and final planning permission was granted, site clearance work began in June 2011 and the windfarm was energised less than a year later in April this year.
What is particularly notable about windfarm construction is that engineers must deal with climactic and topographical conditions that few others in the building industry have to contend with. “There were days when the wind was too strong for the cranes to be used,” said Energia projects director Brian Linton. “Working at 1,000ft lack of visibility because of fog or low-cloud could be a real issue. You would go up one day and it would be calm, but the cranes were still not in use and you would ask ‘Why?’ and the crane operator would just point upwards and you would see that the cloud cover had fallen to just below the top of the crane or the towers and work was impossible! It could be very frustrating, but the project was completed to schedule, safely, with no lost time incidents.”
To complete the project Energia worked in cooperation with ESB Networks who had to complete a major upgrade of the Garrow Subtation with a new 20MVA 110/20kV grid transformer and 110kV HIS switchgear. “This was the first installation of this type of switchgear for a distribution wind-farm connection,” said Gearóid Quinn, ESB Networks’ Renewables Stakeholder Manager . “Particular attention had to be paid that the design fully catered for future requirements as 110kV HIS equipment is not easily adapted once installed on site.”
Brendan McGarr Project Manager handing the keys of Caherdowney Windfarm over to Peter Baillie Managing Director of Energia Renewables.
Progress was good said Noel Cowhey, ESB Networks’ Renewables Project Coordinator: “We lost two days because of the very heavy snow last December, but we had contingencies in place with four-wheel drive vehicles available to take the crews to and from the worksite, which we had covered with a temporary structure, a protective tent, a bit like a marquee, so we weren’t working outdoors. The temporary structure also created a cleaner working environment, which also helped us make good progress.”
The topographical challenge of working on a mountainside is that the peat bog cover can be very fragile. “We have recently completed another project with peat depths of up to 9m.” Linton said: “If proper design, construction, monitoring and maintenance procedures are followed by the developer, consultants and the construction contractors, any impact to the mountain and peat environment can be minimised. Over the years, the Energia Renewables construction team, working alongside our civil consultant, Jennings O’Donovan and Partners, have built up quite an expertise in working in these environments.”
Energia project manager Brendan McCarr added: “At Caherdowney peat depths were around 3m in places, one particular challenge was to install 1,100m of 20kV underground cable, from the site through steep Coillte forest, to link the windfarm with Garrow substation. The cable trenches were excavated down to firm ground and filled with stone to prevent settlement and movement that could otherwise damage the high voltage electricity cable.
“The civil engineering works were carried out by Lagan Construction, who also prepared the Garrow substation site for the installation of the additional transformer and switchgear by ESB Networks. It was quite a tight squeeze at the substation with 15 people from Lagan and 40 people from ESB.”
Quinn says the increase in capacity at Garrow, required for Caherdowney and another new windfarm nearby, was made possible through the innovative use of hybrid insulated switchgear (HIS), which has been developed by Siemens and is SF6 Gas Insulated Switchgear (GIS) suitable for outdoor use and requires a fraction of the space of ‘traditional’ air-insulated switchgear.
The Enercon turbines were manufactured in Germany and transported to the port of Foynes in Enercon’s purpose-built E-Ship 1, a RoLo cargo ship that is remarkable in its use of four large, 27m tall, rotorsails that rise from its deck and that are rotated via a mechanical linkage to the ship’s propellors. These sails, or Flettner rotors, aid the ship’s propulsion by using the Magnus effect, the perpendicular force that is exerted on a spinning body moving through a fluid stream.
From Foynes, the turbines were transported overland by Mar-Train, Ireland’s biggest hauliers of turbine components, with Energia having already readied the route for these exceptional loads, removing trees and diverting overhead lines where necessary. Energia also improved the minor road and the forest track leading to the windfarm site.
Each Enercon E70 turbine has a 64m hub-height and a 70m blade diameter giving an overall tip height of 99m. Towers were delivered in three separate sections, 20m in length with the heaviest weighing 54 tonnes.
“In all, it took nine truck movements to deliver all the components for each individual wind turbine, with us taking delivery of three loads a day over three days for each one,” said McCarr. “We had deliveries on Tuesdays, Wednesdays and Thursdays, and erection works continuing through the Fridays, Saturdays and Mondays to be ready to receive the next delivery the following Tuesday.”
Final commissioning of the grid transformer and the HIS switchgear in the Garrow substation extension was carried out, between March 12th and April 16th, during the agreed outage with EirGrid. Once these pieces of equipment and their supporting control equipment were commissioned, the newly-constructed 20kV Caherdowney cables were connected into Garrow substation.
With the tremendous efforts of both ESB Networks and Energia Renewables’s contractors, the Caherdowney 20kV control building was energised on April 16th and allowed to ‘soak’ before the two circuits to the turbines could be energised on April 17th. Once the turbines were energised Enercon started to commission the turbines with the first export of power to the grid from turbine T1 on Monday April 23rd. Takeover of the wind turbine generators by Energia Renewables was achieved on May 31st.
Energia Renewables Managing Director Peter Baillie said: “We are delighted to be producing sustainable energy in Caherdowney and supplying it to businesses around Ireland. This €14m wind farm represents another significant investment in renewable capacity by Energia.
“Energia Group is one of the most significant contributors to the achievement of Ireland’s renewable targets and one of the largest investors in the renewable sector.
“As part of our commitment to the environment, Energia Renewables has already invested €200 million in developing renewable sources of energy. Our most recent projects are at Corkermore and Drumlough Hill Wind Farms in County Donegal and Crighshane and Church Hill in County Tyrone.
“We want to extend a big thank you to the local community for the support it has given this project. The development of Caherdowney is a very positive step forward for renewable energy in Ireland and local support for the project is a key element to their success.
“All of our wind farm developments bring significant benefits to the local economies, including job creation, increased rates for the local authorities and improvements to local infrastructure such as roads.”
While Energia operates the Caherdowney windfarm, it is now owned jointly by the Irish Infrastructure Fund and Energia, which has a minority stake in the development. The Irish Infrastructure Fund was established by Irish Life Investment Managers and is managed by AMP Capital, who aim to secure and invest up to €1bn for investment in significant Irish infrastructure assets. Looking to the immediate future, Energia are looking to develop a windfarm in east Donegal that will have 40 turbines and an export capacity of 90MW.
“There is a balance to be struck between wind power and generation capacity from gas-burning stations like Huntstown,” said McCarr. “One of the problems with wind is what do you do with the electricity produced when, for example at night, there is insufficient demand. Further development of wind generation capacity will be facilitated by the arrival of smart-metering and the new east-west interconnector between Britain and Ireland, plus developments like electrical vehicles where vehicles are charged overnight. Ireland’s renewable energy sector will continue to grow and Energia is delighted to be taking a lead in that.”