Llanelly power station

Llanelly power station, also known as North Dock power station, supplied electricity to the town of Llanelly and the surrounding area from 1910 to the late 1960s. The power station was owned and operated by a succession of companies, including the Llanelly and District Electric Supply Company Limited, prior to the nationalisation of the British electricity supply industry in 1948. The power station was redeveloped in the 1920s to meet the increased demand for electricity.

History

In 1891 Llanelly Corporation applied for a provisional order under the Electric Lighting Acts to generate and supply electricity to the town. The was granted by the Board of Trade and was confirmed by Parliament through the Electric Lighting Orders Confirmation (No. 4) Act 1891. The corporation did not construct an electricity supply system but transferred the provisional order to J. C. Howell Limited, which was established on 20 December 1905. The provisional order was subsequently transferred to the Limited when it was established in 1911. This company also supplied current for the Llanelly and District Electric Tramways from June 1911 until the tram system closed in September 1932. In 1924 the Lighting and Traction company changed its name to Llanelly and District Electric Supply Company Limited.
Llanelly power station was constructed at the north east corner of the North Dock. The location facilitated the supply of coal for the boilers, and cooling water which was drawn from the sea. Further equipment was added to meet the rising demand for electricity; by the late 1920s the station had a generating capacity of 25 MW.

Equipment specification

Plant in 1923

In 1923 the generating plant at the Llanelly power station comprised:

Coal-fired boilers generating up to 76,000 lb/h of steam which was supplied to:
Generators:
* 1 × 500 kW reciprocating engine with DC generator
* 1 × 750 kW steam turbo-alternator AC
* 1 × 2,000 kW steam turbo-alternator AC
* 1 × 3,000 kW steam turbo-alternator AC

These machines gave a total generating capacity of 6,250 kW comprising 5,750 kW of alternating current plus 500 kW of direct current.
Electricity supplies to consumers were:

12,400 & 6,600 Volts, 3-phase, 50 Hz AC
500 & 250 Volts DC
500 V DC Traction current

Plant in 1923–28

New plant was commissioned and installed at the Llanelly power station from 1923 to 1928. This comprised:

Boilers:
* 2 × 40,000 lb/h boiler, steam conditions 265 psi and 700 °F
* 2 × 60,000 lb/h boilers, steam conditions as above
* 4 × 20,000 lb/h boilers, steam conditions as above

The boilers were manufactured by Babcock & Wilcox and Yarrow and supplied steam to:

Generators:
* 1 × 5 MW British Thomson-Houston turbo-alternator, generating at 6.6 kV
* 1 × 7.5 MW British Thomson-Houston turbo-alternator, generating at 6.6 kV
* 1 × 12.5 MW British Thomson-Houston turbo-alternator, generating at 6.6 kV

The station was supplied with coal via a siding off the nearby dock railway line.
Condenser cooling water was drawn from the sea.

Operations

The supply of electric current in the early years of operation of Llanelly power station was as follows:

Year	Electricity supplied MWh
1915	3,479
1916	4,048
1917	4,359
1918	5,675
1919	5,826
1920	6,761

Operating data 1921–23

The electricity supply and consumption data for the period 1921–23 was:
The electricity loads on the system were:
Revenue from sales of current was £69,818; the surplus of revenue over expenses was £32,186.
The Corporation tramways ceased operating in September 1932.
The supply of electric current in the inter-war period was as follows:

Year	Electricity supplied MWh
1921	7,080
1922	12,605
1923	13,761
1926	12,330
1927	18,300
1929	23,675
1930	24,546
1931	24,092
1932	24,282
1933	26,143
1936	37,952
1938	53,066

Operating data 1946

Llanelly power station operating data for 1946 was:

Load factor per cent	Max output load MW	Electricity supplied MWh	Thermal efficiency per cent
39.7	25,777	83,576	15.15

The British electricity supply industry was nationalised in 1948 under the provisions of the Electricity Act 1947. The Llanelly and District Electric Supply Company was dissolved, ownership of Llanelly power station was vested in the British Electricity Authority, and subsequently the Central Electricity Authority and the Central Electricity Generating Board. At the same time the electricity distribution and sales responsibilities of the Llanelly Electric Supply Company were transferred to the South Wales Electricity Board.

Operating data 1954–67

Between 1964 and 1966 the boilers were converted to oil-firing. Operating data for the period 1954–67 was as follows.

Year	Running hours or load factor	Max output capacity MW	Electricity supplied MWh	Thermal efficiency per cent
1954	4548	24	59,947	14.11
1955	3315	24	39,188	13.83
1956	1992	24	22,122	13.69
1957	1564	24	18,917	13.91
1958	1151	24	13,507	13.75
1961	5.7 %	24	11,933	13.15
1962	4.5 %	24	9,483	13.01
1963	7.0 %	24	14,722	13.64
1967	5.0 %	24	10,413	14.39

The output from the station in MWh is shown on the graph.

Llanelly supply district

Following nationalisation Llanelly became an electricity supply district, covering 161.1 square miles with a population of 106,810 in 1958. The number of consumers and electricity sold in the Llanelly supply district was:

Year	1956	1957	1958
Number of consumers	31,685	32,528	33,171
Electricity sold MWh	337,312	344,323	342,339

In 1958 the number of units sold to categories of consumers was:

Type of consumer	No. of consumers	Electricity sold MWh
Domestic	28,562	30,472
Farms	833	2,397
Commercial	3,344	12,614
Industrial	420	295,439
Public lighting	12	1,417
Total	33,171	342,339

Closure

Llanelly power station was decommissioned in the late 1960s, and was demolished in 1972.