Welcome to

ESB was established in 1927 as a corporate body in the Republic of under the Electricity (Supply) Act 1927. As a strong, diversified, vertically integrated utility, ESB operates right across the electricity market: from generation, through transmission and distribution to supply.

In terms of generation, ESB currently operates 7 thermal stations, 12 windfarms and 10 hydro stations in the , one of which is Turlough Hill.

Turlough Hill, Ireland’s only pumped storage power station, is located approximately 60km south of Dublin City in the . Construction commenced in 1968, and the station became fully operational in 1974.

The station generates up to 292MW during peak demand periods by releasing water from its upper reservoir and allowing it to flow through its four turbines into a lower YEARS reservoir. During periods of lower demand 40 the water is pumped back to the upper reservoir ready to be used again. In 2004, Turlough Hill became the Hydro Control Centre (HCC) for the entire ESB hydro fleet Turlough Hill which contains 19 generators in total. HYDRO STATIONS CLADY CO DONEGAL All linked by Turlough 4 CAPACITY (MW) Hill as the Hydro Control Centre for the fleet

9 95 1 1 SHANNON 92 CO CLARE Contents 9 86 Capacity (MW) LEE 4 Part 1 CO CORK 7 27 CAPACITY (MW) 9 Electricity for an expanding economy 1 Turlough Hill Part 2 CO WICKLOW

How pumped storage works 292 CAPACITY (MW) 1

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Part 3 7 9 Generation and more: today and into the 1 future

Part 4

Turlough Hill technical data and key facts 1 1 5

9 LIFFEY ERNE CO KILDARE Design Zahra Media Group CO DONEGAL 38 CAPACITY (MW) Colour photography (except 65 CAPACITY (MW) ) Neil Warner

The upper reservoir at Turlough Hill esb.ie 1 01Turlough Hill

Electricity for an expanding

economy The original control room at Turlough Hill which served the station until 2004 when the HCC was commissioned

y the late 1960s, ESB had supplied A rapidly responsive pumped-storage chosen because of Lough Nahanagan, a electricity to customers in Ireland for hydroelectric station was the solution and natural corrie lake, which could become the Bmore than 40 years. It had become would be a huge advantage to customers lower reservoir for the station. There was apparent that electricity demand would across Ireland at peak electricity demand also a suitable site on the mountain where continue to grow rapidly across the country times. ESB could build an artificial upper reservoir. and ESB needed to respond quickly and in an environmentally friendly way to help See diagram page 10 Once approval was granted by the Irish manage this booming demand for power. Government, construction on Turlough Hill ❱❱ How Turlough Hill helps smooth out the typical began in1968 and ended six years later. Designing and developing a pumped-storage electricity demand over 24 hours. hydroelectric station was a unique and Staff from many departments within innovative civil engineering solution for Ireland Getting started ESB were involved in the construction at the time. It would expand the electricity ESB’s engineers began looking for the right phase, as well as external contractors who supply for the growing population through location in . The ‘Garden of helped to bring the project to life. At the an environmentally-friendly system and also Ireland’ features many mountains and lakes time of completion, Turlough Hill was provide flexibility when it came to handling the and is in close proximity to Ireland’s main the largest civil engineering project ever challenging peaks and troughs in demand. centre of demand – Dublin. Turlough Hill was undertaken in Ireland.

2 Turlough Hill The new hydro control centre(HCC) at Turlough Hill’ esb.ie 3 CAVERN DIMENSIONS The cavern housing the power station is the same ESB was always very space as a medium-sized conscious that we cathedral. were working in an The dimensions are: length 82m, breadth area of outstanding 23m, height 28m. natural beauty. The cavern is 15m below the water level of the lower reservoir. ‘‘ Taking care ESB was working in an area of outstanding natural beauty and wanted to ensure minimal impact wherever possible. Digging in The project really caught the public’s im- The main station was buried out of sight, agination at the time – it was the country’s inside the mountain, but ESB also: The 220 kV Compound at Turlough Hill first and only pumped storage station. There ❚ hired landscape architect Sylvia Crowe had not been anything of this scale built in to camouflage the upper reservoir with Ireland since the Shannon Scheme was built vegetation and design the works at the in the 1920s. The construction team worked lower resevoir to fit into the background of All systems go! for more than six years: rock; In December 1973, ESB Turlough Hill’s first ❚ carving a massive underground chamber ❚ successfully used a pioneering technique generating unit started operating, followed Cross-section view of cavern in the granite mountain to house the main to restore grass growth on the verges of by the three other units in the summer 1. Pump Turbine 2. Motor/Generator station, so that it would be hidden from the newly-constructed two-mile long road of 1974. And this incredible feat of civil 3. Main Unit Tranformer view (length 82m, breadth 23m, height to the mountain top, using a mix of water, engineering has been supplying Ireland with 4. Flap Gate 28m – the same space as a medium-sized fertiliser, wood pulp, peat moss and grass electricity ever since. 5. Turbine Inlet Valve cathedral); seed; 6. Pony Motor/Generator ❚ ❚ In 2004, ESB Turlough Hill became the Hydro 7. 10 kV Switchgear, Control excavating 2.5 million tonnes of rock to used the 1.305 million cubic metres of Panels and Relays. build the upper lake, then lining it with granite excavated from the upper reservoir Control Centre (HCC) for the company. This 8. 2 x 70 ton Bridge Cranes asphaltic concrete; to build its embankment (maximum height: means that ESB can operate any of its 10 9. False Roof with ❚ drilling tunnels through the rock to 34m, length: 1,445m); hydro stations direct from one single control Soundproofing connect the station and upper/lower lakes. ❚ ensured that the administration offices room on site – increasing its responsiveness 10. Haunch Beams 11. 50 ton Bridge Crane and transformer compound could not be to customer needs even further. 12. Cable Gallery for seen from the Road. 220 kV Cables 4 Turlough Hill esb.ie 5 02Turlough Hill

How pumped storage works

Work begins on the upper reservoir conventional hydro power station sits on a river, moving water from one A reservoir above a dam through a station and then out to rejoin the main river. Pumped storage differs slightly because it uses two reservoirs:

The upper reservoir: At Turlough Hill, this Any pumped storage is the artificial lake. Water flows down a system can help pressure tunnel, then through the station smooth out the and the generation turbines to produce ‘demand curve’ by electricity, similarly to a conventional hydro generating electricity power station. at peak times to help meet demand and using The lower reservoir: At Turlough Hill, this ‘the ‘off-peak’‘ electricity is Lough Nahanagan. The water from the in the quieter hours to upper reservoir ends up here after moving pump the water back through the station generators. That water is to the top reservoir then pumped back up to the upper reservoir again, ready for the using a reversible turbine, ready to be next peak demand resused when needed. window.

6 Turlough Hill esb.ie 7 Electricity demand curve

5000 help meet those electricity needs, releasing Pressure shaft and water from the upper reservoir through the tail race tunnel 4500 turbines and down into Lough Nahanagan. The reversible pump turbines, operating under a mean geodetic head of Water is then pumped back up to the 4000 285.75 m are fed through upper reservoir during the night, using a single pressure shaft 3500 cheaper electricity generated by other and single tail race tunnel stations, so that the whole system is ready both excavated in granite,

MW’s to go again when demand increases the the 4.8 m diameter 3000 pressure shaft being steel next day. Overall, it helps to smooth out the lined and the 7.2 m –––––––– Electricity demand ‘demand’ curve ›› see the diagram diameter tail race tunnel 2500 –––––––– Effect of Turlough Hill opposite and helps makes generation being concrete lined. operations much more efficient. 2000 12:00 21:00 15:00 18:00 03:00 09:00 06:00 00:00 00:00

TIME 2 The effect of the Turlough Hill scheme on a typical load profile

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3 The key to making pumped storage work effectively lies in when it is run. As pumped storage is so responsive, it can be an ideal 6 way to help smooth out the peaks and 4 troughs of electricity demand.

7 Demand is higher at certain points during 5 the day (‘peak time’) as people need more electricity and much lower at night (‘off Cross-section of Turlough Hill from upper 1. Upper reservoir peak time’). 2. Intake tower and reservoir to Lough Nahanagan bridge 3. Pressure shaft Running a pumped storage hydro electric (steel lined) station at peak times helps to smooth out the 4. Cavern demand peak. It’s 6pm and everyone’s at 5. Tailrace tunnel (concrete lined) home, cooking dinner or catching up on the 6. Tailrace structure news? Turlough Hill is probably running to 7. Lough Nahanagan (natural lake)

8 Turlough Hill esb.ie 9 Turlough Hill Generation and more: today and 03 into the future

Today ESB continues to evolve its business in supplying electrity across Ireland. The Gen- eration part of ESB that was responsible for Turlough Hill still exists but its remit and activity have expanded.

It not only operates ESB’s generation as- The tunnel leading down to the cavern which houses the power station, sets, it also develops and trades them with following its completion the implementation of this business model: ❚ Asset Development identifies and devel- ops new generation assets; Power grid ❚ Generation produces electricity from those Communication assets; and ❚ Trading takes that electricity and the associated commodities and trades them Operation & Monitoring on the market. Service Provider Markets Our asset portfolio includes approximately 4,300MW of generation in the Single Electricity Market (SEM) of the island of Ireland. Smart Smart future Grid ESB understands that the delivery of an E-car Generation electricity network is not about the tech- nologies and smart generation alone. The collective smartness of its users is key and ESB will continue to play a core role in maximising the full benefit of smart Transmission Distribution technologies for a sustainable future.

10 Turlough Hill esb.ie 11 Hydro station network

Hydro Generation traces its core purpose The future Pumped Storage right back to the building of and Hydro Ardnacrusha and the creation of ESB ESB strategy has set its Generation Control Centre in 1927: providing a reliable supply of business on a path of growth and change, electricity for customers, for the setting out its ambition to be a company economy and for the future in a safe, of scale in the Irish and UK markets. To cost-effective and sustainable way. help achieve that ambition, the Generation ‘‘ business has set the following strategic objectives: ❚ Build a sustainable position of scale in the Generation fuel mix in 2014 Ireland and UK markets. Grow ESB’s Irish and UK generation portfolio to 7GW and approximately 7% market share by 2025; ❚ Deliver a balanced low carbon generation portfolio that reflects the balance in the Peat 5% Irish and UK markets; Wind 8% ❚ Integrate generation and supply Hydro 11% operations in the Irish and UK markets to Coal 18% optimise earnings and mitigate risks Gas 58% across the value chain; ❚ Optimise the return from the ESB’s Ireland Some examples of current activities in and UK assets by delivering excellent ESB that support those objectives include: asset performance and managing costs ❚ A highly-efficient, low carbon-generating Generation capacity to maximise trading and commercial 880 MW Carrington power plant near opportunities. Manchester; 4.0 ❚ Developing a project pipeline of power Total installed 3.5 plants in the UK; 3.0 dispatchable capacity ❚ Investing in renewable technologies 2.5 3.8 by location (GW) 2.0 to reduce the carbon intensity of the GW 1.5 generation portfolio; 1.0 ❚ Developing alternative and newer 0.5 0.5 0.5 technologies, including biomass, offshore 0.0 Did you know… Turlough Hill is Ireland’s Republic of Northern Great Britain only pumped-storage hydro station. wind, solar and wave energy. Ireland Ireland

12 Turlough Hill esb.ie 13 04Turlough Hill

Technical data and key facts

Excavating the cavern, which would house the massive power station

he main plant is housed in an under- and water hammer pressure rise under fault Data for water conduits ground power station 82 metres long, conditions of approximately 40% above pressure shaft T23 metres wide, with a height of 30 normal. Length 584m. metres. The operating floor level is 15 metres Internal diameter 4.8m. below low water level in the lower reservoir. The machine governors are electro/ Velocity at nominal turbine output 6.25m/sec. hydraulic with load control and joint control Velocity at nominal pump output 4.92m/sec. The main machines when rotated in of all machines. different sense act as turbines or pumps and Upstream manifold correspondingly give or take energy from Data for mechanical and electrical Internal diameters 2.4/3.4/4.15m. the network. The power is nominally about equipment 73 MW in each mode per machine with 4 sets of vertical design, consisting of Pump Tailrace tunnel regulation down to lower loads in the turbine Turbines, and synchronous motor generators Length 106m. mode. The machines can also operate as with pony motors. Internal diameter 7.2m. synchronous condensers in either direction. Mean geodetic head 285.75m. Velocity at nominal turbine output 2.86m/sec. Mean flow (turbining) each 28.3 m3/sec. Velocity at nominal pump output 4.92 m/sec. Rotational speed of the machines is 500 Turbine output each 73.0 MW. r.p.m with a max temp. runaway speed of Mean flow (pumping) each 22.1 m3/sec. Downstream manifold 780r.p.m. based on an inertia per machine Pumping load each 68.2 MW. Internal diameters 3.50/5.00/6.20m.

14 Turlough Hill esb.ie 15 Turlough Hill is situated close to Glendalough See also diagrams Key facts Ireland’s only The Glendasan and page 6 and 11 pumped-storage Glendalough valleys ❱❱ cross-section view of cavern hydro station Upper reservoir historically had thriving (page 6) and Cross-section of ❚ Holds 2.3 million cubic mining communities. Lough Nahanagan metres of water is a natural lake Turlough Hill from upper reservoir to Lough Nahanagan (page 11) 2004Turlough Hill became the The underlying ❚ Excavated 2.5 million and holds twice the usable cubic metres. Hydro Control Centre (HCC) rock is granite tons of rock ❚ for ESB’s 10 hydro stations 40acres/16.2ha/ PRESSURE 160,000 square metres of waterproof lining SHAFT Hydro The first unit went live in Lower reservoir ecause of the reversibility of Mechanical auxiliaries include ❚ Built an embankment CONNECTING Pumped Storage 1973. The other three ❚ Lough Nahanagan is a ‘the‘ electrical machines, two 70 ton cranes to handle nearly 1 mile long/ THE TWO operating since 1974 natural lake and holds 292MW phase change over links are transformers weighing 70 tons nearly 30m high B 1. Intake Structure twice the usable cubic LAKES IS provided on the busbars. Access each and generator rotors 2. Ring Drainage Gallery OVERALL CAPACITY and availability problems weighing 130 tons each and a 3. Access Gallery metres 4 turbines with a capacity 4. Inner Access Ramp ❚ necessitated the use of single 50 ton crane for the spherical 60km south of Around 48.8m deep 584m of approx. 73MW each 5. Outer Access Ramp ❚ phase transformers in the cavern, isolating valves. The entire plant is 6. Access Steps Dublin, Wicklow Corrie lake left by a glacier IN LENGTH three per pair of main sets with air conditioned. 7. Visitors’ Platform at end of last ice age 8. Access Bridge Mountains 22 kV cables to the outdoor 9. Ring Road switchyard. The artificial upper reservoir has a 10. Access Road from Wicklow Gap capacity of 2.3 million cubic metres Did you know… Before the station was built, the hill didn’t have a name on Start up in the pump direction is of water and a maximum operating the Ordnance Survey map. The engineer who carried out the original survey by a shaft mounted Pony Motor of depth of 19.4 metres. It was formed and recommended the site, J O’Riordan, decided to name the hill after his 5.5 MW. The water having been partially by excavation and partly by 1. Drainage layer of son, Turlough. previously exhausted from the the use of the excavated material crushed sound rock, graded from 150mm to pumps by compressed air. in the construction of a ring shaped 10% passing 2mm. rock fill embankment. 2. Rock filling. ‘TURLOUGH’ 3. Drainage layer of Excitation of the main rotors crushed sound rock IS THE GAELIC is thyristor controlled. Starting An asphaltic concrete lining graded from 200mm to Turlough Hill in each mode and change of covers the floor, inner slopes, 10mm, with blinding of took 6 years to NAME FOR A Catchment crushed rock from 55 area of mode of operation is auto- and crest. A ring shaped under mm to 35 mm. build. At its peak DRY LAKE – ONE matic following a push button floor drainage gallery is provided 4. Asphaltic Lining- there was approx. 681M WHICH LOSES ITS MILLION OF ROCK TONS command. Standby auxiliary at the foot of the inner slope of Spray coat of Cut Boat 1.81 Bitumen. Asphaltic RPM power is provided by both a house the embankment to collect and 500 500 people WATER THROUGH km² Concrete binding and Did2.5 you know…The station can go from standstill to full machine, (1000 kVA), and an monitor any seepage through the equalizing course ROTATIONAL SPEED working on the HIGH A SWALLOW HOLE 5 cm in thickness. generation in 70 seconds – stations using other kinds of outdoor diesel set. asphaltic concrete lining. Dense asphaltic construction. 136th highest Cross-section of Turlough Hill from upper reservoir to Lough Nahanagan IN DRY WEATHER. fuel (for example, gas) can take up to 12 hours. concrete course 6cm OF THE MACHINES summit in Ireland in thickness. Mastic sealing coat. 16 Turlough Hill 5. Ring Drainage Gallery Turlough Hill

The position of Turlough Hill in the Wicklow Gap

Turlough Hill is situated on the Wicklow Gap close to the scenic Glendalough

Further reading For further information please visit www.esb.ie www.esb.ie