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Didcot A - The End of an Iconic Era

On Tuesday 23rd February 2016 almost half of a decommissioned coal-fired power station collapsed killing at least one worker, possibly four, as they were preparing it for demolition. At the time of writing the cause of the collapse is unknown, but, a week later, the emergency services are still on site trying to "sift" through the rubble and pile of tangled metal in a bid to find the three workers who are still missing.

History of Didcot A

The Didcot A coal-fired power station was built in the 1960s and began life on 30th September 1970 under the ownership and management of the Central Energy Generating Board (CEGB).

Using on and old Army and RAF ordinance site the CEGB built Didcot A at a time when Britain’s electricity demand was on the increase. Didcot A consisted of four 500MW coal fired turbines which produced enough electricity to power two million homes. Despite local opposition the planning and construction went ahead providing work for many local people over many years.

Building a power station in an area considered to be a place of natural beauty was not without it’s challenges however as considerable money was spent to try and reduce its impact on the landscape. High calibre architects Frederick Gibberd and Partners were instructed to improve the functional layout of the plant which is situated on a 300-acre site in the Vale of the White Horse in Oxfordshire.

This in itself was considered an unusual location to build a power station, but from an economical point of view it was considered better than transmitting electricity from further afield.

Even though there was no coal site at hand the use of the railway line brought coal direct from the East Midland coal field and the River Thames, conveniently close by, provided the cooling water.

So the four 500MW generating units were constructed, along with six cooling towers and a 200m high chimney. Those cooling towers, visible for miles around were often referred to as a blot on the landscape. But those iconic towers were a cheerful sight to many a weary traveller as they returned to the county after trips away.

There was plenty of infrastructure that needed to be built to enable the supply and reliable operation of Didcot A. The coal, after having any debris removed, was pulverised before entering the furnace. The generating units, driven by steam, would produce electricity at 23,500 volts AC which was then increased to 400,000 volts by means of transformers, before being transported by the National Grid.

The 114m high cooling towers were each designed to cool 9 million gallons of water per hour and during the course of the day around 1 million gallons would evaporate. The rest flowed back to the river.

Why did Dicot A have to close?

For many years the burning of coal has been associated with pollution and a significant contributor to climate change. A European Union Directive, the Large Combustion Plant Directive (LCPD), requires member states to limit the flue gas emissions from combustion plant that have a thermal capacity of 50MW or more. The emission limits were for sulphur dioxide, nitrogen oxides and dust.

Didcot A came into this category giving the plant owners a choice to either limit or clean up the emissions or opt-out. The first option would require considerable re-investment on a power station that was already over 40 years old. The second option reduced the future life of the power station to 20,000 hours meaning it had to close by the end of 2015.

Didcot A became one of 9 to opt-out and was the third to cease generating. This happened on 22nd March 2013 and the power station was officially closed on the 31st March 2013. During the 43 years of its lifetime it had generated over 250 billion Kilowatt hours of electricity and was a significant contributor to Britain's power demand.

The Future

As the Secretary of State did not intend to list Didcot A it was free to be demolished to make way for new employment properties.

With the help of 70 staff the decommissioning process was completed in less than five months and deconstruction is expected to be finished by the end of 2016.

Three of the cooling towers were demolished with 180kg of explosives in July 2014 and the remaining buildings have slowly been going through a dismantling process.

It’s the end of an era for Didcot A and the clouds of steam that used to sit above Didcot, but for the time being, at least Didcot will still be producing some power at it’s B plant.

Didcot B

Didcot B was built in the 1990s by National Power and started generating electricity in 1997. RWE Npower then took on the management in 2002. It generates up to 1,360MW of electricity using combined cycle gas turbines(CCGT).

Three months after the demolition of three of the cooling towers from Didcot A, four of the cooling towers at Didcot B caught fire because of an electrical fault in one of the fans. This raised speculation about the lights staying on over the coming winter. See article.

Unless further investment is made to reduce emissions of sulphur dioxide and nitrogen oxides this power station will be closed in 2023 just 26 years after it started generating.

March 2016

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