Colchester power station

Colchester power station supplied electricity to the town of Colchester, Essex, England and the surrounding area from 1900 to 1960. It was owned and operated by Colchester Corporation prior to the nationalisation of the electricity supply industry in 1948.  The power station was redeveloped several times incorporating new plant.

Colchester power station
CountryEngland
LocationColchester
Coordinates51°52′59″N 00°55′35″E
StatusDecommissioned
Construction began1896
Commission date1900
Decommission date1960
Owner(s)Colchester Corporation
(1894–1948)
British Electricity Authority
(1948–1955)
Central Electricity Authority
(1955–1957)
Central Electricity Generating Board
(1958–1970)
Operator(s)As owner
Thermal power station
Primary fuelCoal
Turbine technologySteam turbines
Cooling sourceRiver water and cooling ponds
Power generation
Units operational2 x 1.25 MW, 1 x 3.75 MW
Nameplate capacity7.5 MW
Annual net output9,499 MWh (1946)

History

In 1893 Colchester Corporation applied for a Provisional Order under the Electric Lighting Acts to generate and supply electricity to the town. This was granted by the Board of Trade and was confirmed by Parliament through the Electric Lighting Orders Confirmation (No. 2) Act 1893 (56 & 57 Vict. c. xxxv).[1] The power station was built on Hythe Quay and first supplied electricity in 1900.

Equipment specification

By 1923 the generating plant comprised:[2]

  • Coal-fired boilers generating up to 48,000 lb/h (6.05 kg/s) of steam, these supplied steam to:
  • Generators
    • 1 × 150 kW reciprocating engine driving a generator
    • 1 × 250 kW reciprocating engine driving a generator
    • 1 × 350 kW reciprocating engine driving a generator
    • 1 × 375 kW reciprocating engine driving a generator
    • 1 × 500 kW reciprocating engine driving a generator
    • 1 × 750 kW reciprocating engine driving a generator

These machines had a total generating capacity of 2,375 kW of direct current (DC) power.[2]

Electricity supply was at 420 & 210 Volts DC.[2]

New plant 1955

The plant in 1955 comprised:[3]

  • Boilers:
    • 4 × Vickers Spearing boilers with chain grate stokers
    • 1 × Babcock boiler with chain grate stoker[3]

The total evaporative capacity was 82,000 lb/h (10.3 kg/s), steam conditions were 250 psi and 650°F (17.2 bar, 343°C), steam was supplied to:

  • Turbo-alternators:
    • 3 × Allen’s geared 1.25 MW turbo-alternator
    • 1 × Allen’s geared 3.75 MW turbo-alternator

The total installed generating capacity was 7.5 MW, with an output capacity of 6 MW.[3]  

Condenser cooling water was drawn from the river Colne and was cooled in two cooling ponds of 0.45 million gallons per hour (0.57 m3/s).[3]

Operations

Operating data 1921–23

The operating data for the period 1921–23 is shown in the table:[2]

Colchester power station operating data 1921–23
Electricity Use Units Year
1921 1922 1923
Lighting and domestic use MWh 570 573 582
Public lighting use MWh 19 20 30
Traction MWh 448 354 362
Power use MWh 687 538 610
Total use MWh 1,728 1,485 1,585
Load and connected load
Maximum load kW 1,321 1,270 1,316
Total connections kW 3,213 3,515 3,613
Load factor Per cent 18.0 17.3 18.5
Financial
Revenue from sales of current £ – 34,944 35,588
Surplus of revenue over expenses £ – 8,545 14,074

Under the terms of the Electricity (Supply) Act 1926 (16 & 17 Geo. 5 c. 51)[4] the Central Electricity Board (CEB) was established.[5] The CEB identified high efficiency ‘selected’ power stations that would supply electricity most effectively. The CEB also constructed the national grid (1927–33) to connect power stations within a region.[5]

Operating data 1946

Colchester power station operating data in 1946 is given below:[6]

Colchester power station operating data in 1946
Year Load factor per cent Max output load MW Electricity supplied MWh Thermal efficiency per cent
1946 18.0 6,172 9,499 9.59

The British electricity supply industry was nationalised in 1948 under the provisions of the Electricity Act 1947 (10 & 11 Geo. 6 c. 54).[7] The Colchester electricity undertaking was abolished, ownership of Colchester power station was vested in the British Electricity Authority, and subsequently the Central Electricity Authority and the Central Electricity Generating Board (CEGB).[5] At the same time the electricity distribution and sales responsibilities of the Colchester electricity undertaking were transferred to the Eastern Electricity Board (EEB).[7]

Operating data 1954–58

Operating data for the period 1954–8 is shown in the table:[3]

Colchester power station operating data, 1954–8
Year Running hours Max output capacity  MW Electricity supplied GWh Thermal efficiency per cent
1954 390 6 1.201 6.51
1955 645 6 2.269 7.28
1956 610 6 2.215 7.86
1957 437 6 1.468 7.57
1958 663 6 2.536 8.98

Colchester power station was part of the Colchester electricity supply district.[3] This district served an area of 195 square miles and a population of 103,600 (1959). It included Colchester, West Mersea, Wivenhoe, Lexden, Winstree, Maldon, Tendering and Samford. The number of customers and the electricity sold was as follows:[3]

1956 1957 1958
Total number of consumers 32,776 33,523 34,378
No. of domestic consumers 28,967 29,386 See below
Units sold kWh 110,612 122,866 139,218
Domestic units sold kWh 40,753 44,390 See below

In 1958 the number of units sold to categories of consumers was as follows:[3]  

Type of consumer No. of consumers Units sold kWh
Domestic 30,169 48,845
Commercial 2,154 19,890
Combined premises 599 2,596
Farms 6,309 6,309
Industrial 517 60,854
Public lighting 15 724
Total 34,378 139,218

There were 735 miles (1183 km) of high voltage mains in the district comprising 281 miles (452 km) of underground mains and 454 miles (731 km) of overhead cables.[3]

Closure

Colchester power station was decommissioned in about 1960.[8]

See also

References
  1. "Local Acts 1893". legislation.gov.uk. Retrieved 15 October 2020.
  2. Electricity Commissioners (1925). Electricity Commissioners, Electricity Supply – 1920–23. London: HMSO. pp. 22–25 266–271.
  3. Garrett, Frederick (1959). Garcke's Manual of Electricity Supply vol. 56. London: Electrical Press. pp. A-46, A-118, B-150-151.
  4. "Electricity (Supply) Act 1926". legislation.gov.uk. Retrieved 15 October 2020.
  5. Electricity Council (1987). Electricity supply in the United Kingdom: a Chronology. London: Electricity Council. pp. 45, 60, 69, 73. ISBN 085188105X.
  6. Electricity Commissioners (1947). Generation of Electricity in Great Britain year ended 31 December 1946. London: HMSO. p. 7.
  7. "Electricity Act 1947". legislation.gov.uk. Retrieved 15 October 2020.
  8. Data for Colchester power station is given for 1958 in Garrett (1959), but Colchester is not on the CEGB Annual report for 1961
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