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How to find us Take the first exit across the bridge to the next Didcot A and B power stations are just off the A4130 roundabout. For the B station, take the first exit left on the outskirts of the town of Didcot in Oxfordshire. and follow the signs for the B Station Security Gatehouse. For the A station, take the second exit left and follow From Oxford and the north the signs for the A Station Security Gatehouse. Take the A34 south bypassing Abingdon until the junction with the A4130 is reached. Take the second Visit www.npower.com/education to: exit at the roundabout and travel to the next round- • Find out more about our ‘Energy to live, energy to about. Take the first exit across the bridge to the learn’ education programme. next roundabout. For the B station, take the first exit left and follow the signs for the B Station Security Gatehouse. For the A station, take the second exit • Order online npower’s free educational Power Pack resources for Key Stages 1–4, which focus on energy and power. Didcot Power Stations left and follow the signs for the A Station Security • Get helpful lesson ideas and activities from our Gatehouse. Renewable Energy education web link. From High Wycombe and the east via the M40 . Leave the M40 at Junction 7 Take the A329 to Wallingford. At Wallingford take the A4130 to Didcot. At Didcot follow the relevant signs for both stations. From London or the west via the M4 and Newbury and the south Leave the M4 at Junction 13 and follow the A34 northwards until the junction with the A4130. Take the 4th exit at the roundabout and travel to the next roundabout. npower Didcot A and B Power Stations Didcot Oxfordshire OX11 7HA T (0)1235/51 22 91 F (0)1235/51 60 97 Design WPA Pinfold 0061/09/04 E email@example.com I www.rwenpower.com Flexible power from RWE npower, part of the RWE Group, is a leading integrated UK energy company. We are one of the UK’s coal and gas largest energy suppliers. We have over 8,000MW of generation capacity in the UK from our diverse portfolio of flexible, low-cost generation assets, sell our expertise The npower site at Didcot is host to two power stations in power generation in key markets and are market leaders – the 2,000MW dual-fired A station and the 1,360MW in renewable energy development. combined cycle gas turbine B station. Together the two power stations are capable of producing npower, one of the UK’s leading energy Our current operational wind farms suppliers serves around 6 million have a combined capacity of 267MW, enough electricity to meet the needs of over 3 million residential and business customers. with many other projects at various people – equivalent to the demand of three counties the We are also commited to developing stages of development. We have innovative products which allow our nine hydroelectric power stations in size of Oxfordshire. customers to make sustainable energy Scotland and Wales, with a combined choices, such as our domestic green capacity of some 50MW. energy product, npower Juice. We are market leaders in both onshore and offshore wind energy developments and operation and small-scale hydroelectric generation in the UK. 01 Coal supply 05 Generator 08 Cooling towers The coal is delivered to the station The generator rotor is directly coupled The warmed river water from the by train and placed on the stockpile to the turbine shaft and rotates condensers passes to the six cooling or taken by conveyor to the boiler within the stator. As the turbine shaft towers, where it is sprayed over house. spins, it rotates the generator rotor, packing in the base of the tower, an electro-magnet weighing 74 tonnes. and cooled by evaporation in the Didcot A began commercial operation in 1970 as a 02 Pulverising mill The electromagnet is energised by natural up-draught of air. Some of The coal is ground as fine as face direct current from the exciter, the cooling water condenses into coal-fired power station. It developed the capability to powder in a pulverising mill, picked a small generator situated at the tiny floating droplets, like an early up by a powerful stream of hot air outboard end of the main generator. morning mist. This creates the water operate flexibly in response to the variation in demand and blown into the boiler to burn vapour plume that can be seen like a gas. Electricity is generated in the stator: coming from the top of the towers. for electricity. a series of hollow, insulated, copper Lower winter temperatures increase 03 Boiler conductor bars that are cooled by condensation making the plume The heat produced converts extremely pure water. Power is larger. extremely pure boiler feedwater produced at 23,500 volts alternating Didcot A is a dual-fired power station, Because of changing market and into steam in the 500 kilometres current. Each of the four generators 09 Electrostatic precipitators of tubing that form the boiler walls. produces 500MW when running at Before the boiler gases are owned and operated by npower part environmental factors, three of its The steam leaves the boiler at full capacity. discharged from the main chimney, of RWE npower. Commercial operation four 500MW generating units were a temperature of 568°C and at some 99% of the fine dust, began in 1970 and the station can converted to dual-firing, in order 165.5 bar. 06 Generator transformer produced by burning pulverised Electricity from the generator is coal, is removed from the flue generate 2,000MW of electricity – that they can burn natural gas as an For greater efficiency, the steam produced at a voltage of 23,500 gases by electrostatic precipitators. enough power to meet the needs alternative to coal. Didcot A became passes through the boiler twice. volts. For transmission along the of some 2 million people, equivalent the first large power station in the UK national grid system, the voltage Coarse ash falls to the bottom Three of Didcot A’s four boilers have is increased to 400,000 volts in of the boilers where it is sluiced to twice the total population of to have this facility. been modified to burn gas as well as the generator transformer. out, crushed and carried by high Oxfordshire. coal. Special burners have been fitted pressure water to settling pits. The station is at the forefront of that reduce the amount of oxides of 07 Condenser nitrogen in the boiler gases. The spent steam from the turbine The ash and dust is sold for use Didcot A was originally designed as technological innovation in the way exhaust goes to the condenser, in civil engineering projects or for a coal-fired power station operating plant is controlled. The main control 04 Turbine where it is turned back into water by the manufacture of building blocks. at base load, and has subsequently room has the latest computer-based The steam passes through the passing over tubes containing cold Surplus pulverised fuel ash is blades of the turbine’s high pressure water drawn from the River Thames. pumped to Radley to reclaim developed a capability to operate systems, to assist the operations staff stage, turning the blades and The condensate is pumped back disused gravel pits. flexibly in response to variable power to maximise plant performance and to turbine shaft at 3000 revolutions to the boiler for re-use. demands at lower load factors. minimise costs. per minute. The turbine shaft is linked to the generator. The steam returns to the boiler for reheating, and then goes back to the turbine’s intermediate pressure stage and three low pressure stages. The power process at Didcot A 08 01 03 05 04 09 07 06 02 As part of the UK’s commitments to CO2 reductions under the Kyoto Protocol, the government has set an indicative target of 10% of electricity to be supplied by eligible renewable sources by 2010. The Renewables Obligation (RO), which came into effect in April 2002, is a key policy instrument in the government’s strategy to achieve these targets. Renewable targets can be met from a variety of sources, including wind, hydro and biomass generation. Following successful wood biomass Co-firing of biomass in an existing co-firing trials at Didcot A Power power station provides a much more Station to determine if there were immediate source of renewable any environmental and operations generation and clearly has a role in impacts, we received approval from meeting both the electricity suppliers. the Environment Agency (EA) for It can also play an essential role in commercial operation of wood providing an initial market for biomass, (as sawdust) co-firing. Since gaining supporting both the forestry industry EA approval we have constructed a and sustainable agriculture through the biomass/coal blending facility that encouragement of energy crops. could replace up to 2% of the coal we burn with biomass (Didcot A burnt 3.7mt of coal in 2003). Didcot B has two electricity 04 Generator 09 Cooling towers generating modules. Each module Inside the generator, the rotor Warmed river water from the consists of two gas turbines (which (an electro-magnet) turns inside the condenser passes to 31 low-level are similar in principle to a jet engine) stator (made up of copper bars) and cooling towers. The river water and a steam turbine – each turbine creates an electric current. Each gas passes through side radiators, has an associated generator. The turbine generator has an output of cascades through plastic packing, exhaust gases from the gas turbines 225MW of electricity. and is cooled by a stream of cold pass through special boilers, known air. The air is drawn in by low-noise as heat recovery steam generators 05 Heat recovery steam fans, which are set in the top of the 09 (HRSGs), where steam is raised to generator (HRSG) cooling towers. supply the steam turbines. On leaving the turbine, the exhaust gas (now at around 545°C) passes The towers are specially designed 01 Filters through the HRSG (which is a dense to minimise the frequency of visible The air needed by the gas turbine matrix of finned tubes), where up to plumes of water vapour, normally is drawn in through an intake filter 320 tonnes of high pressure steam associated with traditional cooling and then compressed in the turbine per hour is raised for the steam towers, and they are plume free for compressor. turbine. Finally, the waste gas most of the year. (now at a temperature of 93°C) is 02 Combustion chamber discharged to the atmosphere 10 Generator transformer The compressed air enters the through the chimney. Electricity from the three generators 05 combustion chamber at over 16 on each module is produced at a times atmospheric pressure. The air 06 Steam turbine voltage of 15,750 volts. This is 06 is mixed with natural gas and burned Steam from the HRSG is fed to the stepped up to 400,000 volts in the in the combustion chamber. steam turbine where it turns the generator transformer, before the 08 The burning air-gas mixture is at a blades on the turbine shaft. electricity is passed to the National 07 temperature of 1160°C – hot enough Grid Company’s substation on the 03 01 to melt glass. 07 Steam turbine generator Didcot A site for transmission The turbine shaft turns the around the country. 03 Gas turbine generator rotor to produce 230MW 02 The exhaust gas expands through of electricity. the blades of the gas turbine turning 04 10 the blades and turbine shaft at 3,000 08 Condenser revolutions per minute. The turbine The spent steam from the turbine shaft is linked to the compressor and exhaust goes to the condenser, the generator. where it passes over tubes containing cold water drawn from the River Thames. The condensate is pumped to the feedwater storage tank and then back to the HRSGs and used again in a continuous cycle. Great Crested Newt – a protected species carefully moved to a new home on the Didcot site. Caring for the community and the environment Didcot A and B power stations play We offer guided tours of the site a major role in the local community. to interested parties, to foster a Rather than downplay our presence, greater understanding of the power we aim to work in harmony with our generation process and our care for neighbours, and we meet regularly the environment. with representatives from Didcot and surrounding villages to consider the Didcot A has always been at the views of local people. forefront in recognising the importance of environmental care. A Field Study We have valued links with local Centre and Nature Reserve were authorities and educational established on an area to the west of establishments. We sponsor a number the site. This natural habitat for wild of local educational projects and plants, birds and animals is visited by environmental initiatives. We also thousands of schoolchildren each year. support a wide range of community groups and charities through our Conservation work is continuing by charitable giving programme and the protection of wild orchids that have employee volunteer scheme. a special place in the ecology of the Didcot site. A colony of the protected Great Crested Newt was relocated from the Didcot B site to the Nature Reserve prior to the construction of Didcot B. Field study centre at Sutton Courtenay. Landscaping included the preservation While Didcot A is less efficient than of as many existing trees as possible. Didcot B, it plays a vital part in A substantial programme of planting balancing demand for electricity has been undertaken on both sites, throughout the day. with some 30,000 trees and shrubs being planted to date at Didcot B. Great care is taken to limit the environmental impact of both stations. The high efficiency of Didcot B power We endeavour to keep noise and station, together with the composition nuisance to a minimum. Extensive of the natural gas fuel, results in the monitoring is carried out of site noise station having minimal environmental levels, emissions to the atmosphere, impact. and discharges of cooling water into the River Thames. Compared with an equivalent-sized, coal-fired power station, Didcot B Both A and B stations operate under produces virtually no emissions of licences granted by the Environment sulphur dioxide, half the carbon dioxide Agency and operating conditions and less than a fifth of the amounts agreed with the local authority. The of oxides of nitrogen. environmental record of both stations is open to public scrutiny through the At Didcot A, major improvements have publication of independently-verified, been made by the installation of low annual Environmental Performance NOx burners, the capability to burn gas Reviews. on three of the four generating units, and a £20 million investment project in Environmental management systems dust capture efficiency. at Didcot A and B are certified to international standard ISO 14001.
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