Dolgarrog power station

Dolgarrog power station in Dolgarrog, Wales was originally built in 1907 as part of an aluminium smelting plant. It uses water turbines to drive electricity alternators. Public supplies began in 1922 when power lines were constructed to transmit electricity from the power station to Colwyn Bay, Conwy and Llandudno. The station was vested in the British Electricity Authority and its successors following nationalisation in 1948. It is currently (2021) operated by RWE NPower UK.

Dolgarrog power station
CountryWales
LocationDolgarrog
Coordinates53°11′28″N 03°50′33″W / 53.19111°N 3.84250°W / 53.19111; -3.84250Coordinates: 53°11′28″N 03°50′33″W / 53.19111°N 3.84250°W / 53.19111; -3.84250
StatusOperational
Commission date1907
Owner(s)Aluminium Corporation of Dolgarrog
(1907–1920)
North Wales Power Company Limited
(1920–1948)
British Electricity Authority
(1948–1955)
Central Electricity Authority
(1955–1957)
Central Electricity Generating Board
(1958–1990)
National Power
(1990–2000)
Innogy plc
(2000–2002)
RWE Innogy
(2002–present)
Operator(s)As owner
Power generation
Units operational2 × 5 MW; 1 × 6.5 MW; and 1 × 10 MW
Nameplate capacity27 MW
Annual net output74.1 GWh (1958)

HistoryEdit

Dolgarrog hydro-electric power station was commissioned in 1907 by the Aluminium Corporation of Dolgarrog to supply electricity to its aluminium smelting plant.[1] The smelting of the mineral bauxite to make aluminium is an energy intensive process requiring a large amount of electricity.[2] The availability of cheap hydro-electric power was therefore attractive. The construction of the power station was sanctioned under the provisions of the North Wales Electric Power Act 1904. Water was drawn from Llyn Cowlyd and Llyn Eigiau, via a system of leets and tunnels.[3] There are two 48-inch (1.22 m) diameter pipelines providing a working head of 830 feet (253 m) and 1130 feet (344 m).[3]

The Aluminium Corporation of Dolgarrog acquired a controlling interest in the North Wales Power and Traction Company in 1918. Ownership of the power station was transferred in 1920 to the Power Company which was subsequently renamed the North Wales Power Company Limited.[1] The Power Company also owned and operated the power stations at Cwm Dyli and Maentwrog.[4]

In 1924–25 the North Wales Power Company increased the capacity of the power station by adding two Pelton wheels coupled to 5 MW alternators.[5] This was known as No. 2 station.[3]

In the mid-1930s the Company sought to further expand the power station. The Electricity Commissioners gave consent to the addition of a new 6.5 MW generating set.[5] A new 6-feet (1.83 m) diameter pipe was installed to extend the existing 48-inch (1.22 m) pipe to Cowlyd dam. The North Wales and South Cheshire Joint Electricity Authority (JEA) supported the North Wales Power Bill which increased the share capital of the Power Company to £3 million. Money was therefore available to finance the extension. The power bill was enacted as the North Wales Electric Power Act 1936.[6]

The British electricity supply industry was nationalised in 1948.[1] The North Wales Power Company Limited and the JEA were abolished and ownership of Dolgarrog power station was vested in the British Electricity Authority and its successor organisations. The North Wales Hydro-Electric Power Act 1952 (15 & 16 Geo. 6 and 1 & 2 Eliz. 2. C. cxlvi) provided for the extension of the Dolgarrog and Maentwrog catchment area including a 10 MW extension to the plant at Dolgarrog power station.[1] This was No. 3 Station.[3]

The British electricity supply industry was privatised in 1990.[7] At that time the net capability of Dolgarrog power station was 27 MW from four machines. The station was designated Dolgarrog High-Head power station (18.4 MW) and Dolgarrog Low-Head power station (14.98 MW). Ownership was vested in National Power in 1990 which demerged as Innogy plc in 2000. This was acquired by RWE of Germany in 2002. The station is currently (2020) operated by an Innogy subsidiary Innogy Renewables UK.[8]

Plant and equipmentEdit

The power station was developed in stages as outlined above; technical details are as follows.[3]

No. 1 stationEdit

Commissioned in 1909, comprising a Boving Pelton wheel with Bruce Peebles 1.2 MW, 6.6 kV alternator.[3]

No. 2 stationEdit

Commissioned in 1924–25 and comprising 2 Pelton wheels driving 2 × 5 MW AC alternators. In 1936 a third Pelton wheel was installed coupled to a 6.5 MW alternator.[3]

No. 3 stationEdit

Commissioned in 1957, comprising one Boving-Bruce Peebles 10 MW set operating at 750 rpm and with a working head of 750 feet (229 m). There were Ferranti step-up transformers from 6.6 kV to 20 and 33 kV.[3]

Plant summaryEdit

In 1979 the plant at Dolgarrog power station comprised 2 × 5 MW; 1 × 6.5 MW; and 1 × 10 MW turbine & alternator sets giving a net capability of 27 MW. The oldest machine had been installed in 1924.[9]

The generator sets are currently (2020) are numbered 2, 3, 4 & 5; all are Francis turbines manufactured by Weir, Weir, Boving & Gilkes respectively, with alternators by GEC-Alsthom (Nos. 2, 3 & 5) and Peebles (No. 4).[10]

OperationsEdit

In 1921–23 the electricity statistics for the North Wales Power Company's Dolgarrog power station were:[11]

Dolgarrog power station operating data 1921–23
Year 1921 1922 1923
Electricity generated MWh 6,888 6,487 8,691
Electricity purchased MWh 1,040 2,270 3,248
Electricity sold MWh 7,928 8,757 9,939
Maximum load kW 3,360 4,600 5,000
Total connections kW 7,500 9,000 11,000
Load factor per cent 26.8 21.7 22.6
Revenue from sales £29,563 £34,727
Surplus revenue over expenses £16,010 £17,766

Operating data for the period 1921–86 was:[3][4][11][12][13]

Dolgarrog power station utilisation and output, 1921–86
Year Running hours Max output capacity  MW Electricity supplied MWh Load factor per cent
1921 5.5 1,736 26.8
1922 5.5 1,643 21.7
1923 5.5 8,459 22.6
1936 45,434
1946 No.1 43.1
1946 No.2 21.4 52,400 28.0
1954 8760 17.7 45,959 29.6
1955 8752 17.7 66,246 42.8
1956 8784 17.7 34,203 22.0
1957 8758 27.7 58,136 34.9
1958 7350 27.7 74,103 36.1
1961 28 67,260 27.7
1962 28 70,984 29.3
1963 28 47,551 19.39
1967 26.5 61,700 26.2
1972 27 39,439 16.9
1979 27 58,737 24.8
1982 27 65,942 27.9
1986 27 64,334 27.3

The output in GWh is shown graphically.

The station is currently (2020) operated by Innogy Renewables UK.[8]

See alsoEdit

ReferencesEdit

  1. ^ a b c d Electricity Council (1987). Electricity supply in the United Kingdom: a Chronology. London: Electricity Council. pp. 38, 66. ISBN 085188105X.
  2. ^ "The Aluminum Association". 25 October 2020.
  3. ^ a b c d e f g h i Garrett, Frederick (1959). Garcke's Manual of Electricity Supply vol. 56. London: Electrical Press. pp. A-50, A-141.
  4. ^ a b Electricity Commissioners (1947). Generation of Electricity in Great Britain year ended 31 December 1946. London: HMSO. p. 12.
  5. ^ a b Electricity Commissioners (1936). Electricity Commissioners 16th Annual Report 1935 to 1936. London: HMSO. pp. 107–08.
  6. ^ Electricity Commissioners (1937). 17th Annual Report 1936 to 1937. London: HMSO. p. 122.
  7. ^ "Electricity Act 1989". legislation.gov.uk. Retrieved 25 October 2020.
  8. ^ a b "RWE Generation UK". Retrieved 25 October 2020.
  9. ^ Electricity Council (1979). Handbook of Electricity Supply Statistics 1979. London: Electricity Council. p. 12. ISBN 0851880762.
  10. ^ "Dolgarrog Hydro-electric Power Station (85420)". Coflein. RCAHMW. Retrieved 30 September 2021.
  11. ^ a b Electricity Commissioners (1925). Electricity Supply 1920-1923. London: HMSO. pp. 228–231, 514–519.
  12. ^ CEGB Annual report and Accounts, 1961, 1962 & 1963
  13. ^ CEGB Statistical Yearbook 1972 to 1986, Central Electricity Generating Board