On Monday 30 September 2024 at 3.10pm, a 500-megawatt (MW) turbo-alternator at Uniper Energy’s Ratcliffe-on-Soar power station in Nottinghamshire commenced a staged 25-minute run down, reducing the electricity it was exporting to the grid from 480MW to zero.
At 3.35pm it was desynchronised for the final time, marking the end of electricity produced from coal in Great Britain after 142 years.
Coal put on notice
The deadline for the cessation of coal had been formally agreed between the British government and the energy sector as January 2025. The 2000MW power station at Ratcliffe-on-Soar, which opened in 1968, was the last one to close. Having received the last delivery of coal via train six weeks earlier, when the last ounce of coal ran out, generation stopped.
Ratcliffe was equipped with four huge generators, known as ‘units’, each with its own boiler and furnace. Unit 4 was running on the final day, with Unit 3 bowing out two days earlier. In her heyday Ratcliffe would run all four units together, delivering 2000MW to the grid, or up to 8% of the nation’s electricity flat out for 18-24 months between maintenance outages, and then repeat.
Power stations which ran around the clock were known as ‘base load’ generation and Ratcliffe was the top of the merit order, meaning she was the most efficient to operate and ultimately the lowest cost. When the electricity industry was privatised in 1990, operating regimes changed and became more market-driven. Operators would choose to run their plant according to market price, and certain stations were switched off in full or in part at night. This was known as ‘two shifting’. Whilst it added wear to the plant, it was arguably more profitable.
Ferranti wins the current war
The first coal-fired power station in the world opened in January 1882 on London’s Holborn Viaduct. This groundbreaking station used 110V DC dynamos from Thomas Edison’s company and had a capacity of 2,200 incandescent lamps, a technology demonstrated barely three years earlier. It featured boilers by Babcock & Wilcox, the manufacturer who made the huge boilers for Ratcliffe-on-Soar 84 years later. Whilst Edison was a prominent advocate of direct current electricity (DC), a bright young British engineer by the name of Sebastian Ziani de Ferranti favoured the use of alternating current electricity (AC). AC has the benefit of being able to change the voltage to different levels using a transformer, allowing electricity to be transmitted over distance at higher voltages, thereby reducing losses and increasing efficiency.
Ferranti championed this method and built the largest AC power station in the world at Deptford in 1887. This vast powerhouse, which was to have an ultimate capacity of 80MW (an incredible target in the 1880s!) would light two million lamps. Ferranti chose Deptford due to its riverside location for cooling water and the delivery of coal. He would send the electric current to London on cables at 10,000 volts. The station, machinery, switchgear, transformers and cables were all designed by him. He was just 23 years old at the time.
Turbo charged
In 1890 in Newcastle-upon-Tyne, the Forth Banks power station became the first in the world to be equipped with steam turbines, an invention from 1884 by Sir Charles Parsons. Steam turbines allowed direct coupling of the generators and could run at higher speeds than the previous reciprocating engines. They also allowed finer control and provided greater fuel efficiency.
After some improvements at Cambridge power station, turbines quickly became the default choice to drive electrical generators, and alternating current had largely won the battle of the systems between AC and DC. As power stations grew in capacity, the turbo-alternator was firmly established as the means of turning hot steam into electrical power. The boilers were predominantly powered by coal, the annual consumption of which in British power stations continued to rise, reaching a peak of 90 million tonnes in 1980.
Set sizes rose rapidly after the turn of the 19th century, passing 1.5MW in 1905 and 105MW by 1935 when the first half of the famous Battersea Station was commissioned. This was the largest generator in the world at the time. At the end of World War II, electricity demand in Great Britain was rising exponentially and the government nationalised the electricity supply industry, forming the British Electricity Authority (BEA) to own and operate all the country’s power stations and run the national grid. Fourteen area Electricity Boards were also formed to handle regional distribution and sell the electricity, which the BEA produced, to domestic and industrial customers.
Super stations for a super grid
The BEA commenced an ambitious programme of power station construction and built a new national grid to be superimposed over the existing grid, by then 20 years old and reaching capacity. This new ‘supergrid’ allowed the connection of larger power stations, which could be sited by fuel and water supplies, on cheaper land, some distance from the demand centres. The BEA completed several power stations started by municipal authorities and brought forward their own stations including so called ‘super stations’ along the Trent and Aire valleys. These stations were easily served by the productive coalfields of the East Midlands and Yorkshire. The mighty station at Castle Donington in Derbyshire was the first to use 100MW sets driven from a single boiler and the first to break away from the ‘red brick’ design to a steel structure covered by cladding.
This made construction cheaper and faster. By the early 1960s, the BEA had evolved into the Central Electricity Generating Board (CEGB) which planned 13 major new stations based on 500MW turbo-alternators. All but three of these stations were to have 2000MW output. Ratcliffe was the eighth to be completed. The aim of the expansion programme was to focus generation on a smaller number of locations and allow the supergrid to transport the electricity to where it was needed. The first 500MW unit to synchronise to the grid was at Ferrybridge, near York, in February 1966. Ratcliffe, which was the twin sister of Ferrybridge, synchronised her fourth and final unit in October 1970.
Big boilers
Each of Ratcliffe’s huge boilers converted half a tonne of water into steam every second at 2400psi and 568⁰C. At full load, each unit burned 200 tonnes of coal every hour and a full boiler weighed 10,000 tonnes. The boiler was able to ‘store’ ten seconds of energy and the turbine one second. The station would typically burn 6.5mn tonnes of coal every year or 20 full trains’ worth every day. The coal stock, visible for miles around, held around 1.2mn tonnes.
As recently as 2012, 40% of the electricity generated in Great Britain came from coal. The government announced the phase out of coal in the electricity system in 2015 which led to several station closures, the private owners choosing to avoid the ongoing maintenance and refurbishment costs. Deep coal mining in the UK ended in December of that year, all coal being imported thereafter with subsequent fuel quality and cost challenges.
Exceeding life expectancy
Super stations like Ratcliffe were only designed to run for 25 years, then be dismantled and recycled when worn out. Many have far exceeded their original design expectations, through impassioned and dedicated stewardship from the professional engineers and craftspeople charged with their care. Drax, near Selby in Yorkshire, converted four of her six 660MW sets to run on biomass and eventually mothballed the remaining two. Ratcliffe stayed with coal, but her activity in the latter months had dwindled to just one or two units, when demand and market conditions justified her start up. After 56 years at the forefront of powering the nation, she has now retired.
The date had been looming for many years, but it is difficult to fully comprehend the level of emotion or poignancy for the station staff, some of whom had worked there for 40 years or more. Many started as apprentices at the age of 16 and have never worked anywhere else. All staff have been redeployed or will be retained for the decommissioning and demolition works. The electrical capacity of Ratcliffe-on-Soar, the last coal power station in England, was 133,000x greater than that of the Holborn Viaduct, the first coal power station in England and the world, 142 years earlier.
Over that period, British power stations burned through 4.6bn tonnes of coal and emitted 10.4bn tonnes of carbon dioxide. This is more than most countries have ever produced from all sources. Whilst coal undoubtedly contributed not only to British industrial and economic growth but also the technical development and evolution of global power system engineering, the time was right for Britain to kick the habit and become the first G7 country to remove coal from its electricity generation mix. Thank you, coal, and goodnight.
