Power station fuels

Our fossil fuel-fired power stations all need a regular and reliable source of fuel. Numerous and complex factors determine how we source our fuel and can include various legal restrictions (such as the amount of sulphur in coal), as well as the more obvious economic drivers. The proportion of fuels used from one year to the next will vary to reflect these factors. The common unit 'million tonnes of coal equivalent' (Mtce) is used to show the proportions of different fuels used based on their energy content.

Fuel Used By Generation, Mtce

	2002	2003	2004	2005	2006
Fuel used Coal	6.81	9.97	8.49	8.52	8.49
Fuel used Gas	5.86	5.78	5.48	5.55	5.17
Fuel used Oil	0.06	0.03	0.23	0.51	0.34

Mtce = million tonnes of coal equivalent

During 2006, there was a reduction in the amount of fuel we used, reflecting an overall decrease in generation, partly due to an unplanned outage at Ratcliffe-on-Soar power station and partly due to reduced demand following slightly warmer weather and changes in consumer behaviour.

Fuel use by generation/useful product supplied, Mtce/TWh

Fuel Used By Generation, Mtce/TWh

2002	2003	2004	2005	2006
0.30	0.34	0.32	0.33	0.33

Mtce/TWh = million tonnes of coal equivalent per TeraWatt hour

Electricity generation efficiency, in terms of fuel used per unit of useful product supplied, has changed little over the past five years, remaining at around 0.33 million tonnes of coal equivalent per terawatt hour (Mtce/TWh).

Transport fuel use

Our Central Networks and Energy Services commercial fleet vehicles use a significant amount of fuel to carry out their operational activities.

Transport fleet - fuel use, litres

	2005	2006
Central Networks	3,146,976	3,627,440
Energy Services	N/A	3,009,345

Energy Services was formed in 2005.

The pattern of fuel use from Central Networks' commercial fleet is affected by a wide range of operational factors including work scheduling, network improvements and routine and emergency maintenance. Energy Services is a growing business and its fuel use is largely determined by the volume of contracted work.

Water use

Our power stations generally use water as a coolant and are usually located by a river or on the coast. The water used in the cooling process is returned to source at temperatures usually within a degree or two of its original temperature. A proportion is lost to the atmosphere as water vapour from power stations with cooling towers, depending on atmospheric conditions. Process water is extracted from a variety of potable and non-potable sources, and the overall quality of the process water we discharge is close to that abstracted. Abstraction and discharges are stringently regulated by the Environment Agency.

Water Use, Million m3

	2006
Cooling water	1,723.22
Hyrdoelectric	169
Process water	18.73

The volume of process and cooling water used by our thermal power stations depends on how often they are called on to generate. We don't directly measure the volume of water we abstract directly from rivers and sources other than the mains supply; however, we do take calculations based on flow rates and running hours. Many of our plants are now used to meet peak demand rather than running baseload, which means that water usage can be difficult to calculate. Therefore, a number of assumptions regarding flow rates and other factors are made to ensure the estimations are as accurate as possible. Much of the water is reused a number of times before finally being discharged. We plan to carry out water efficiency audits over the next couple of years as part of the Integrated Pollution Prevention and Control (IPPC) improvement programme.

Naturally, our hydroelectric plant at Rheidol, near Aberystwyth in Wales, uses a large quantity of water directly for electricity generation, almost all of which is unmodified and returned after use.

Hydroelectric water use, Million m3

2002	2003	2004	2005	2006
170	132	187	165	169

Like any other business with office-based operations, our employees and buildings also use a significant amount of potable water. In 2006, our offices, including the Power Technology Centre, used some 51,059 cubic metres of water*, as calculated from our utility bills. Our Facilities department monitors water usage statistics through a buildings management programme and is assessing ways in which water consumption might be reduced.

* The figure reported in 2005 also included water use from our engineering workshops and has since been revised after internal quality checks revealed an error in the orginal calculation. The revised figure for 2005 is 69,405 cubic metres and includes all facilities managed offices (including some pre-2005 data for New Broad Street) and the Power Technology Centre.

Further details of the environmental performance of each of our sites are available here and detailed environmental trend data going back to 1990 is available here.