Calorific Value is a measure of heating power. All fuels, from gas to diesel to coal and wood, have their own Calorific Value upon combustion. We will focus on natural gas here, as an example of how Calorific Values are calculated and used by one fuel industry.
The ‘CV’ of gas is expressed in megajoules per cubic metre (Mj/m3), which represents the amount of energy that is released when ‘a known volume of gas is completely combusted under specified conditions’. The CV of gas is measured at a standard temperature and pressure (15 degrees centigrade/1013.25 millibars).
What is Calorific Value used for?
Calorific Value measurements are essential for those involved in the energy business such as co-op energy and Scottish Power. They are the benchmark used down the entire supply chain to determine costs. Using gas as an example, CV measurements are used to bill those who transport and supply gas. They, in turn, use the Calorific Value to arrive at a figure to charge the end user. The consumer can use Calorific Values to compare suppliers, and see how their bills are calculated.
How is Caloric Value determined?
As in other industries, there are international standards governing measurement, as well as the Gas (Calculation of Thermal Energy) (Amendment) Regulations. These regulations assert where and when CV measurements are made, and what equipment must be used to in the process. The process is overseen by government body Ofgem, who enforce the regulations and audit primary data.
What instruments are used to measure Calorific Value?
The measurement of Calorific Value in natural gas is measured continuously, through the use of chromatographs. These machines measure the amount of each constituent of natural gas, by type. Natural gas is a hydrocarbon gas mixture, made up of several different types of gas. The largest of these by volume, is methane, Other measurable are also present, such as helium, ethane, carbon dioxide, nitrogen and hydrogen sulphide. A chromatograph singles out each compound and measures the quantity of each present in the gas. The overall CV value is calculated from these measured quantities.
Where Are Chromatographs Located?
The chromatographs are located all over the UK, at ‘reception stations’ which are attached to the National Grid. There are 110 locations at the present time. A very large user of gas, such as a gas station fired power stations, have their own CV measuring chromatographs attached to incoming gas lines, so that a totally accurate measurement can be made on site. For the rest of us, a calculation is made differently. The UK is divided into 13 different charging sections, and an average CV is taken from across these in order to arrive at a billing figure. So, domestic and industrial users of gas will be billed according to the daily CV averages in their own billing area, according to the volume of gas they consume.
Estimated average calorific values of fuels
The Government issues estimated average calorific values of fuels. For example, the estimated average calorific value of power stations is 27 CJ per tonne gross, while the estimated average calorific value of hospital waste is 14 GJ per tonne gross. To discover more colorific values, visit https://www.gov.uk/government/statistics/dukes-calorific-values.
CVs For Fair Billing
By using CV measurements, the power industries can ensure a fair, consistent and transparent method of charging domestic and business customers the correct price for fuel.