CAUSE 2003 Home               Previous Dispatch         Dispatch Home        Next Dispatch

From the Holyhead Post-Road to Transporting Electrons

Day 10: Cynwyd, to Dinorwig, to Llangollen, to Cynwyd

by MorganWindram

Outside Exhibit:

The power station which is completely underground is composed of a Pelton Wheel Turbine commissioned in Cwm Dyli built in Nant Gwynantin in 1906 next to Snowdon (highest mountain in Wales).

The unit was No. 1 of 4 generating a total of 6 megawatts to supply the slate quarries of Blaenauffestiniog, Dinorwig, Bethesda, and Dyffryn Nantle. All units here were replaced in 1988.

Edision Mission Energy (an Edison International Company) now controls the plant.

Background of Area:

Dinorwig Slate Quarry—largest in the world. Exported many tones of coal. 160 years in business, closed in 1969. At peak it employed 3,000. Closed with 300 employees.

Natural lakes power the power station using the scheme of ‘pumped storage.’ These lakes are glacial in origin.

Power Station Tour:

Bussed down into the mountain (Elidir MountainK) which was geology of main Ordovician rocks and intrusive tertiary rocks. This power station has the world’s fastest response generators built within Europe’s (largest man made) cavern. The power station took three years to dig the tunnels out. Twelve million tons of slate waste blasted out. After 7 years of digging, electrical equipment was ready to be instituted, but not before ‘schockcrete’ a synthetic concrete was applied to the walls to serve as a protective ‘skin.’ It helps hold the tunnels together.

Workings of the Plant:

-There are 6 water taps
-15,000 gallons of water per second is pumped through the taps and the valves can be opened in 5 seconds.

Water flows through valves, hits turbine wheels which rotate at 500 rev/minute. Shaft enters generator which handles 313 watts of energy, but if all 6 generators are being used, they could generate power for all of Wales for 5 straight days.

It takes 1.5 minutes from cold stand-still to generate power. There is a 24 ton stainless steel backup wheel. This is a 78% efficient power station.

The main inlet valve holds back a column of water from here to the upper reservoir, 600 meters above.

There are bat colonies that hide in the caves here. They are a rare breed of horseshoe bats.

In the Pump turbine Hall, they push compressed air in underneath flat turbine wheels which reduces friction and they convert the generator into electric energy. It is synchronized with the National Grid.

This is the highest value civil engineering project in the UK.
Fastest power response in the world! 1320megawatts within 12 seconds of demand!
Each of 6 generator motors weighs 382 tons.
Each rotor 445 tons

All power lines and station are built underground because of environmental concerns. Salmon and trough diversion tunnels of 2.2kmlong have been built. The station is inside Snowdonia National Park. The lake is home to arctic Chad, which was transferred to nearby lakes with similar habitats.

The first main tunnel at Dinorwig collapsed; they had to dig and rebuild a new tunnel for the main tunnel. In the dredging of the power station, 2 boats were found under the castle (12th century welsh castle Dolbadam).

The power station is ¾ of a mile in the mountain.

Pumped Storage:

Opened the wheel at the side to fill the tank at the top. Once the water reaches marked level, it can be stored until you release it to spin the turbine and light the bulb. The water stays in lower reservoir and can be pumped back again when energy is not needed for anything else. Over 3 million tons of rock excavated and placed in slate quarry and lake bed. 16km of tunnels, one million ton aggregate, 200,000 ton cement, 4,500 steel linings used in construction.

Snowdonia’s Glaciers:

In Ogwe n 320m thick and Llaberis (300m thick) last ice age 10,000 years ago.
Vegetation-Saxifrages—limestone loving alpine plants, snowdon lily (rare).
Dynamics: change from oak woodland to disturbed forest (by man’s activities).

History of Slate Quarries:

1890 at Blaenau Ffestinog, Richard Breaves, (ownver of Llechwedd Slate Quarry) installed a water wheel operated 32 volt generator which drove air compressor. 1904, the company had hydro-electric station which works still today.

Chirk Aqueduct—In Chirk outside Llangolen, built in 1795-1805 by Thomas Telford.

Pontcyille Aqueduct—Built also by Thomas Telford in 1795-1805
18 piers made of local stone
-central ones: 126 feet high up to the iron work
-canal: non-trough, 1007’long, 11’10” wide, 5’3” deep
-iron supplied by William Hezerdine
-total cose: 47,000 pounds
-over the River Dee


Morgan Windram is a Senior in Geography.

CAUSE 2003 Home               Previous Dispatch         Dispatch Home        Next Dispatch

Last updated: Wednesday December 03, 2003