# Portsmouth power station

Portsmouth power station supplied electricity to Portsmouth and the surrounding area from 1894 to until 1977. The power station was built and operated by Portsmouth Corporation and started supplying electricity on 6 June 1894. It was located in St Mary Street and was redeveloped several times: including major rebuilds in 1927–29 and in 1938–1952, and expanded into a larger plot. The power station was closed in 1977; the two chimneys were demolished in 1981 and the main buildings in 1982.

## History

In 1890 Portsmouth Corporation applied for a Provisional Order to generate and supply electricity to the town of Portsmouth, Hampshire. This was granted by the Board of Trade and was confirmed by Parliament through the Electric Lighting Orders (No.5 ) Act 1890 (54 & 55 Vict. c. cxc). The Portsmouth Corporation electricity undertaking constructed a pioneering power station on a site in St Mary Street (50°47'36"N 1°06'11"W).

## Equipment specification

The first plant and equipment was designed and installed by Sebastian Ziani de Ferranti and comprised horizontal and vertical compound engines and an early example of a Parsons steam turbine these were coupled directly to Ferranti and Parsons dynamos. The machines were supplied by five Lancashire boilers each with an evaporative output of 5,000 lb/h (2,268 kg/h) of steam. There were also motor generators and batteries. In 1898 the electricity generating capacity was 1,386 kW. There were estimated to be 39,407 lamps of 8-candle power plus 257 public lamps. By 1914 the output capacity of the plant was 3,300 kW.

### Post-war plant

Following the First World War new plant was installed to meet the growing demand for electricity. By 1923 the plant comprised:
* Coal-fired boilers generating a maximum of 120,000 lb/h (15.12 kg/s) of steam, these supplied steam to:
* Generators
** 1 × 200 kW reciprocating engine
** 1 × 500 kW reciprocating engine
** 3 × 650 kW steam turbines
** 1 × 1,000 kW steam turbine
** 1 × 2,000 kW steam turbine
** 1 × 4,000 kW steam turbine
These provided a total generating capacity of 9,650 kW.
Camber Dock was opened for colliers to deliver coal to the power station.
Electricity supplies were available to consumers as single phase, 50 Hz AC at 200 and 100 Volts, and 3-phase, 50 Hz AC at 240 and 415 Volts.

### Low pressure plant 1927

New low pressure (LP) generating sets were commissioned in 1927–29.
* Boilers
** 1 × Babcock CTM 88,000 lb/h, operating at 250 psi and 650 °F (11.09 kg/s, 17.2 bar and 343 °C)
** 2 × Babcock & Wilcox CTM each 50,000 lb/h, operating at 250 psi and 650 °F (6.3 kg/s, 17.2 bar and 343 °C), the boilers supplied steam to:
* Turbo-alternators
** 2 × GEC /Fraser and Chalmers 10 MW sets, operating at inlet steam conditions of 245 psi and 700 °F (16.9 bar and 371 °C).

### High pressure plant 1938

High pressure (HP) plant was commissioned in stages: August 1938, September 1941, December 1948, and March 1952. It comprised:
* Boilers
** 2 × Clarke Chapman marine type each 123,000 lb/h, (15.5 kg/s)
** 5 × Bennis quadsum each 165,000 lb/h, (20.8 kg/s)
** 2 × Mitchell each 180,000 lb/h, (22.7 kg/s)
All the boilers worked at 625 psi and 850 °F, (43.1 bar and 454 °C).
* Turbo-alternators
** 4 × British Thomson-Houston 30 MW sets, operating at inlet steam conditions of 245 psi and 700 °F (16.9 bar and 371 °C).
Cooling water for the Hick-Hargreaves condensers was abstracted from the tidal harbour. The water flowrate was 6.6 million gallons per hour (30,004 m$^3$/h).
The turbine hall was 429 feet, by 65 feet by 48 feet tall (131 m × 19.8 m × 14.6 m), and has been claimed to contain one million bricks.

## Operating data

In 1898 the maximum electricity demand was 849 kW and the undertaking sold 981.273 MWh of electricity.
The operating dating data for 1921–23 is shown in the table:
Portsmouth power station operating data 1921–23 :
| Electricity Use | Units | Year | Year | Year |
| Electricity Use | Units | 1921 | 1922 | 1923 |
| Lighting and domestic use | MWh | 3,067.7 | 3,125.4 | 4,341.9 |
| Public lighting use | MWh | 590.8 | 496.86 | 606.7 |
| Power use | MWh | 1,230.3 | 1,591.9 | 1,241.3 |
| Total use | MWh | 4,885.8 | 5,214.1 | 6,190.0 |
| Load and connected load |||||
| Maximum load | kW | 3,410 | 4,050 | 4,700 |
| Total connections | kW | 10,200 | 12,000 | 13,064 |
| Load factor | % | 19.8 | 18.0 | 18.7 |
| Financial |||||
| Revenue from sales of current | £ | – | 117,440 | 128,291 |
| Surplus of revenue over expenses | £ | – | 38,472 | 55,657 |
Under the terms of the Electricity (Supply) Act 1926 (16-17 Geo. 5 c. 51) the Central Electricity Board (CEB) was established in 1926. The CEB identified high efficiency ‘selected’ power station that would supply electricity most effectively; Portsmouth was designated a selected station. The CEB also constructed the national grid (1927–33) to connect power stations within a region.

### Operating data for 1946

Portsmouth power station operating data, 1946
| Year | Load factor per cent | Max output capacity MW | Electricity supplied GWh | Thermal efficiency per cent |
| 1946 | 31.2 | 87.36 | 238.79 | 18.73 |
Upon nationalisation of the British electricity supply industry in 1948 under the provisions of the Electricity Act 1947 (10-11 Geo. 6 c. 54) the Portsmouth electricity undertaking was abolished, ownership of Portsmouth power station was vested in the British Electricity Authority, and subsequently the Central Electricity Authority and the Central Electricity Generating Board (CEGB). At the same time the electricity distribution and sales responsibilities of the Portsmouth electricity undertaking were transferred to the Southern Electricity Board (SEB).

### Operating data for 1954–71

Operating data for the period 1954–71 is shown in the table:
Portsmouth power station operating data, 1954–71 :
| Year | Running hours (load factor per cent) | Max output capacity MW | Electricity supplied GWh | Thermal efficiency per cent |
| HP plant |||||
| 1954 | 6975 | 114 | 498.234 | 24.48 |
| 1955 | 6796 | 114 | 492.762 | 24.11 |
| 1956 | 6775 | 114 | 451.142 | 23.57 |
| 1957 | 6651 | 114 | 472.323 | 24.03 |
| 1958 | 6509 | 114 | 333.132 | 22.97 |
| LP plant |||||
| 1954 | 3519 | 19 | 31.182 | 14.75 |
| 1955 | 2823 | 19 | 24.800 | 14.92 |
| 1956 | 2641 | 19 | 24.759 | 13.20 |
| 1957 | 1663 | 19 | 13.856 | 12.32 |
| 1958 | 1185 | 19 | 10.199 | 14.30 |
| Combined output |||||
| 1961 | (18.3 %) | 143 | 229.40 | 21.76 |
| 1962 | (22.70 %) | 143 | 269.783 | 22.70 |
| 1963 | (27.57 %) | 143 | 345.352 | 22.69 |
| 1967 | (24.6 %) | 143 | 308.023 | 21.15 |
| 1971 | – | 112 | 196.788 | – |

## Closure

The station was disconnected from the national grid on Sunday 20 March 1977 and decommissioned. The two chimneys were demolished in 1981 and the main buildings in 1982. The area has since been redeveloped.