POWER STATIONS AT LITTLEBROOK: INNOVATION IN ELECTRICITY GENERATION
There have been electricity generating power stations on the Manor Way, Littlebrook site since 1939.
The name Littlebrook derives from the Anglo-Saxon name of the stream (Lytelbroc), which for 1000 years, has flowed through the marshes to the river Thames. The stream, today, only reaches the Thames via man-made drainage ditches on the marsh. The site was once a Saxon Manor which can be traced from 1242 to this day. The area around the Stations has yielded both Anglo-Saxon and Roman remains of considerable historic value. Access to the site from Dartford is via Littlebrook Manor Way which has existed for many hundreds of years and may have been used by Roman or Danish invaders gaining access to Dartford.
The current electricity generating site, once known as Littlebrook Farm, was originally chosen since it was capable of development to allow large scale extensions as the necessity arose. The site was purchased by the Kent Electric Power Company in 1936 for major power station development. The site on the river gave good availability of ship borne coal and a plentiful supply of cooling water for the turbines.
There have been 4 power stations constructed - named Littlebrook 'A', 'B', 'C' and 'D'. The current station 'D' is the remaining operational one.
The land is marshy and the general level was raised to the river wall height, when construction began in 1939, as a precaution against flooding. This was insufficient to withstand the general flooding experienced in February 1953 when the basements of 'A' and 'B' stations, and the partially constructed 'C', were under water and the stations were only approachable by boat.
THE "A" STATION
Kent Electric Power Company, a subsidiary of the County of London Electric Supply Company, built the 'A' power station to meet the rapidly increasing demand in their south-east England area. The new station was to come under the control of the Central Electricity Board, since it was being built in their area of supply. The new 'super' power station was being built to deal with the exceptional growth of the demand for electricity, as people were becoming increasingly aware of the advantages of electricity, particularly in the home. Local power stations, such as Barking, were reaching full capacity.
The station was a steam range station with any turbine being supplied
by any boiler via steam receivers. Coal for the station was originally
brought in, for the first year, by rail on a line constructed along Littlebrook
Manor Way.The station was on base load for 15 years and was finally shut
down in 1973.
Design features to prevent major disruptions were incorporated into the building of the power station, since it was being built so close to the outbreak of World War 2. The main electricity switching control room was sited away from the boiler and turbine houses and the 66kV indoor substation walls were built from re-enforced concrete. The station was additionally camouflaged during the war and only received damage on one occasion when a bomb fell into a switch annexe causing some damage to auxiliary plant switchgear but no loss of generation. The turbines were additionally protected during the war by concrete bunkers built around them. The station was guarded by the Home Guard during the war.
THE "B" STATION
'B' station was designed in 1938, contracts were placed before the war but work was delayed because of the war until 1945. The station had a capacity of 120 MW from 2 generators of 60 MW, each being supplied with steam from 4 boilers. The first turbine was commissioned in 1949 followed by second in 1950. A change in fuel policy saw the station converted to burn fuel oil instead of coal by 1970 and the station did not operate beyond 1975.
THE "C" STATION
The Central Electricity Board started work on the new 'C' station designed for a total output of 240 MW in 1949. The first turbine was commissioned in 1952 and the last, of 4, in 1956. Steam from 4 boilers supplied 2 generators each. A change in fuel policy saw the 'C' station converted to burn heavy fuel oil by 1958 and the station finally ceased generation in 1981.
The original design of the whole site allowed for the introduction of the new stations, with the 3 stations built in a north-south direction with the 'A' station nearest to the River Thames. The coal plant and coal storage area, for instance, was extended as necessary to cater for the new stations as they were built.
At its height the combined station workforce of the 3 stations numbered about 1000 people. Following electricity supply nationalisation in 1948, ownership of the Littlebrook stations passed to the British Electricity Authority, under the control of the South Eastern Division of that company.
THE "D" STATION
'D' station was built by the Central Electricity Generating Board from 1977 onwards with the first unit commissioned in 1981. The station was designed as a fuel oil fired station from the beginning - the diversification of fuel supplies being adopted by the CEGB in the 1970s. It incorporated the latest 660 MW, 4-cylinder re-heat design running at 3000rev/min with each turbine output, therefore, being larger than the combined output of the previous 'A', 'B' and 'C' station turbines.
The turbines were designed to be flexible in operation with fast responses to changes in required output. There are also 3 gas turbine units manufactured by GEC capable of 35 MW each which are capable of starting up the station should there be a complete collapse of the grid system.
The station buildings incorporated a local design feature with many of the buildings at ground level being faced in concrete blocks which, on the outside, show local gravel quarried from the immediate area of the Littlebrook site.
A decision by the CEGB to switch to gas as a fuel for power generation eventually decreased the 'D' station load factor in the mid 1990s. Currently only one unit is capable of immediate generation - the other 2 having been mothballed.
An electrostatic precipitator, used to remove dust particles from the boiler flue gasses, was fitted to 2 of the boilers in 1996 and is the first of its kind to be fitted to an oil fired boiler in this country. Current staff numbers are 69 - this from a peak of over 300 following commissioning and full usage. Heavy fuel oil is held in 5 storage tanks at 100,000 tonnes capacity each and oil can be received in ships carrying up to 20,000 tonnes of fuel oil. Such imports are off-loaded from a new main jetty.
Following electricity supply privatisation in 1991, the station ownership
was transferred to the new National Power company (now called Innogy).
Some parts of the 'A' ,'B' and 'C' stations still exist today - the 'A'
station boiler house has been converted to house a reactor simulator,
the 'B' station has been converted to offices and the 'C' station turbine
house wall remains as part of new office buildings. The 'D' station has
utilised the old 'A', 'B' and 'C' station fuel oil tanks as water strategic
storage tanks. The original 'A' station coal jetty has been retained and
is used for the smaller imports/exports of fuel oil via ships. The original
132kV substation, built for the 'A' station, has been largely retained
by the National Grid Company, although modified to accept different circuits.