Last August, John Cook, Steve Lenahan and I visited Westburton A, a 2000 megawatt coal fired power station built in north Nottinghamshire in England in the 1960s. The power station was viewed at the time as pushing engineering advances to the limits. It consumed 1,000 tons of coal an hour and required water to be pumped around its cooling system at a rate of 52 million gallons an hour. Its boiler house was 24 stories tall, its two chimneys stood at over 180m and its eight cooling towers could each comfortably house St Pauls Cathedral. Inserting infrastructure of this size into countryside where the tallest structure till then had been modest church spire created new problems for its architects. Through careful placement of the cooling towers and using different coloured cement to reduce the visual impact of their size, the architects won a Civic Trust Award for “an immense engineering work of great style which, far from detracting from the visual scene, acts as a magnet to the eye.” Strange today to think of awards going to power stations on aesthetic grounds, but in the 1960s in the UK, visual coherence was thought to offset the impact of massive engineering infrastructure on landscapes. The power plant was officially opened on 25 April 1969.
Westburton A is now operated by French company EDF, and the only one of three coal fired power stations in the UK not yet decommissioned. On our visit we were told that the power station had been due to close in September 2021, but that the UK government had asked that it be on stand-by for the coming winter given the uncertainty of power supply due to the Ukraine War. (It was subsequently asked to fire up for a short while in March 2023, and decommissioning began this month). We were then introduced to an engineer who showed us around. He had worked at the power plant for most of his life and would be in charge of the decommissioning. He spoke about how upsetting it would be to him to see blow torches and demolition balls taken to a place that he had looked after for 50 years.
Before beginning our tour of the power plant, we had to put on full PPE gear – helmet, goggles, bright orange lanyard, overalls, boots, gloves and earphones. It all felt rather performative given that the plant was not in operation.
We were driven around the enormous plant site, first passing between the turbine hall and the national electrical grid transformer, through which the electricity generated by the plant is distributed. It exists the turbine hall through cables held on pins marked in red, yellow and blue that look like giant hair clips, crosses the road overhead and then enters the national grid transformer through similar hairpin-like clips. It seemed incredible that this HUGE operation ends up in three fragile looking cables exiting the turbine hall from each generating unit. Electricity exits the power station at 400,000 volts. Regional substations step it down before sending it along transmission lines to consumers.
We drove past a hydrogen store where the hydrogen used to cool the generator is stacked in red torpedo-like containers. We then drove past a store of propane canisters. Propane is used to light heavy fuel oil which used to light the coal to bring the furnace slowly up to the extraordinary pressures and temperatures needed to generate steam. We then past under the conveyor that carries the coal to the coal bunkers, from where they are dropped into grinding mills.
We stopped at the coal yard, now almost empty, picked up small samples and took panoramic photographs.The engineer said that he remembered when the coal was stacked as high as a seven story building.
We then passed the rail shed where the coal and the oil is offloaded. On the other side of the road we drove past a huge bunker where fly ash is stored before being transported dry to the ash dump by truck.
The fly ash dump is a few kms away at Bowl Ing. ‘Ing’ is a word used in Yorkshire for a wet meadow i.e. a wetland. When we got there we found a large flat surface planted with grass, and further away a mound of fly ash topped with soil that was being dismantled and transported away for various uses such as concrete breeze blocks or road construction etc.
On the way back from Bowl Ing, we also passed a huge shed with a pitched roof that we were told was the gypsum shed.
In the 1980s when coal burning was identified as the source of acid rain, massive investment was made to remove sulphur from emissions to meet regulatory standards. This involves using limestone (which has to be mined, crushed, transported to site and turned into a slurry). Massive air suction pipes draw the air emitted from furnaces into a chamber at the base of the plant’s chimneys, where the sulphur bonds with the calcium in the lime and water, to form gypsum. This is then sold to the construction industry to make plasterboard and removed from site by rail.
Before getting to the boiler house, we stopped at the base of one of the cooling towers and the engineer explained the parts these massive structures play in the electricity generation process. The water that is cooled in the towers is not the water used to make steam, but the water used to cool the water used to make steam. It is pumped from the turbine hall and dropped just above the base of the cooling towers over an eggcrate-like surface, emitting its heat through the tower as steam. The water is then pumped back to the turbine hall, replenished with water from the river.
How coal fired power generation works
First, coal is transported as chunks by conveyors to bunkers located two storeys above the ground in the boiler house. From there, it is dropped into mills to crush it to a fine powder. At Westburton A, roller mills are used to crush the coal to a fine powder by way of rolling movement and weight. We saw some old rollers and were amazed at the damage done to heavy steel by this process. Each generating unit at Westburton has six mills (five in action, one spare).
The fine coal ash is then blown from the mills into the furnace, where it is set alight by propane and heavy fuel oil. Once it catches, the propane and fuel oil is extinguished and the coal will burn as long as one allows it to. Inside the furnace, the boiler, which is like a huge kettle contains water drawn from the river, but purified through reverse osmosis. This water is held in huge reserve tanks at the top of the boiler house from which it is fed to a feeder tank by gravity and then into the boiler.
It is in the boiler that steam is produced, under tremendous pressure, where it reaches temperatures of 570 degrees. The engineer told us that at this temperature, steam is invisible, but tremendously dangerous; it acts like a laser and can cut your leg off. We asked him how, in such a complex assemblage of pipes and switches and valves and handles and tanks and so on, it is possible to identify where something has gone wrong. He said:
I use my eyes and my ears. If a valve sounds slightly different, or if I see a small leak I can immediately identify where a problem is coming from and send a message to the control room to turn something off or to alert a maintenance team.
The intimacy between the infrastructure and his bodily senses, built up over years of experience was fascinating. He said that staff also use a flag at the end of a stick to identify steam leaks, which are detected when the flag catches alight.
The burning of coal dust builds up a residue of bottom ash (at the bottom of the furnace) and fly ash, that flies around inside it. Bottom ash is washed out of the furnace into ash pits, where it is crushed and pumped in a slurry to the bins before being transported to the ash pit.
The fly ash is blown over electrodes which take out the heavy particles which drop down into hoppers, from where it is transported to the ash bunker.
The air from the furnace is then suctioned by air through massive pipes into the desulphering chamber before being emitted through the flue. It seemed to us that a lot of the power generating process relies either on gravity, or on air and water being pumped around.
Going back inside again, from the boiler, steam is carried through large, insulated pipes to the turbine chamber where it turns the blades of the turbine in a multi stage approach. As the steam cools, it condenses as water, which is then cooled inside a sleeve of cool water from the cooling tower and then pumped back to the boiler. The two circuits of water (steam water and cooling water) are completely separate.
The turbine blades are on a rotor connected to a generator shaft, which turns at 3000 rpms. This mechanical energy is what is converted into electrical energy. Hydrogen gas keeps the generator cool.
The turbine chamber and generator chambers are actually quite small relative to the hugeness of everything else and the volume of the boiler and turbine halls.This amazed us. To think that the small blue painted cylinder (a 500 MW unit) generated enough power for about 400 homes for a year was incredible, and that the objective of this huge operation, with all its process and counter processes and remediating processes and back up processes was to keep a tiny little rotor spinning!
At the end of the tour, we went back to the administration building where we were each given a memorial glass paperweight with a 3d model of the plant inside it. We were told that, given that approval for a national grid transformer takes about 12 years, EDF had applied for approval to develop the site as a nuclear fusion power plant, which was approved in October 2022. It will be the UK’s first prototype nuclear fusion facility.
On our way out, we were told of the excellent retrenchment / retraining packages that EDF was offering its staff!
This visit was made possible by British Academy Grant no. KF6220264, ‘Reimagining the Good City from Ennore Creek, Chennai.’ Thanks to the EDF staff for permitting us to visit and showing around the plant.
Lindsay Bremner, April 2023.
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