Calorific Value - Observation

Peter_F_59

Hi guys, Newbie here.

I have always thought that a conversion rate would be a constant to do with elements.
I haven't been checking my bills very closely until now and have noticed that the our rate varies between 39.5 and 39.8.
To be honest I don't understand why we are not just charged for the units used.

Cardew

https://www.nationalgrid.com/gas-transmission/data-and-operations/calorific-value-cv

Calorific value (CV) is a measure of heating power and is dependent upon the composition of the gas. The CV refers to the amount of energy released when a known volume of gas is completely combusted under specified conditions. The CV of gas, which is dry, gross and measured at standard conditions of temperature (15oC) and pressure (1013.25 millibars), is usually quoted in megajoules per cubic metre (MJ/m3). Gas passing through our pipeline system has a CV of 37.5 MJ/m3 to 43.0 MJ/m3.

Importance of CV

Knowledge of the CV of natural gas is an essential part of our day-to-day activities, as this information is used to determine the amount of energy we transport. CV information is provided daily to gas shippers and suppliers, which is then used to bill gas consumers. We also use this data to determine transportation charges for gas shippers and suppliers.

Gerry1

Peter_F_59 said:

Hi guys, Newbie here.

I have always thought that a conversion rate would be a constant to do with elements.
I haven't been checking my bills very closely until now and have noticed that the our rate varies between 39.5 and 39.8.
To be honest I don't understand why we are not just charged for the units used.

Welcome to the forum.

You are charged for the units used, but the units are kWh, so it's quite fair.  The issue is that the gas can be 'weak' or 'strong', 'concentrated' or 'dilute' (or whatever you want to call it) so you have allow for that when converting the volume to kWh.

You'd feel a bit ripped off if a £5 bottle of screenwash that had to be diluted with 10 volumes of water was suddenly replaced with a Ready to Use version at the same price !

[Deleted User]

Peter_F_59 said:

Hi guys, Newbie here.

I have always thought that a conversion rate would be a constant to do with elements.
I haven't been checking my bills very closely until now and have noticed that the our rate varies between 39.5 and 39.8.
To be honest I don't understand why we are not just charged for the units used.

Gas is supplied by volume not units. You are charged for the units consumed  (kWh) based on a conversion formula which calculates the amount of energy  (heat) per cubic foot or cubic metre in the gas supplied. Suppliers are not permitted to use a fixed CV conversion. Some of the gas burnt in your home might have come from Norway; Russia or be LNG transported by ship from the Middle East. The latter can have a CV higher than the permitted billing limits:

Quote: LNG has a density of around 430 kg/m³ to 480 kg/m³ and a gross calorific value of around 54 MJ/kg to 56 MJ/kg depending on the composition. Unquote

The fact that it is imported in relatively small amounts and mixed in with other sources means the average CV should be within permitted billing limits. 

wakeupalarm

Energy company has charged CV at of over 60, told them it was an error and had to be between 37.5 and 43, they replied saying they don't set the value!

Anyone have a link to any Ofgem document that states the limits?

[Deleted User]

Here you go:

https://www.ofgem.gov.uk/sites/default/files/docs/2014/08/supplier_guidance_on_cv_calculation.pdf


https://www.gazprom-energy.co.uk/help-and-support/other-useful-information/energy-glossary/c/

You could also work out the correct CV for your billing period and send it to your supplier.

Gerry1

Dolor said:

Here you go:

https://www.gazprom-energy.co.uk/help-and-support/other-useful-information/energy-glossary/c/

If you don't pay in roubles, you're likely to find your caloric value will soon be zero...

jbuchanangb

According to my records, until 1991 I was charged in pence/therm, where therm was cu.ft x calorific value. (Calorific value introduced in 1990, before that charged in pence per 100 cu.ft.) From April 1992, the calculation changed. First cu.ft are converted to cu. metres, then multiplied by calorific value. At that time a volume conversion of 1.0 was also applied. From April 1997 the volume conversion factor changed to 1.02264. The lowest calorific value I have seen is 37.7, and the highest 40.0.

Sea_Shell

On checking my latest bill, it has a calorific value of 39.8.

Strong stuff 😉🤔?