Increase in calorific value of Gas

pooch

oldtrout wrote: »

As it's so complicated, I've previously accepted that the calculations made for converting gas usage into kWh were what they were and fixed.

However, I have a spreadsheet set up with all these calculations included. As I'm on a fixed tariff until April, I did not expect my own figures to differ from that on my latest dual fuel bill.

It's the gas. Admittedly it's only about 40p difference on a 60 day bill period, but it did not reconcile.

Noticed why ... it's an increase in the calorific value from 39.2 to 39.4.

Anyone know what that's all about?

The CV of gas varies. I think it can vary from 37.5 to 43.0 (but rarely falls outside of 38.5 and 41.5)
Because it varies, that is why it is included on every bill so you don't get charged for energy you've not received.

More info here:
http://www.transco.co.uk/services/cvalue/cvinfo.htm

C_Mababejive

macman wrote: »

Isn't the CV primarily determined by the amount of water in the gas? More water content lowers the calorific value.

Not not really although you do touch on a very important point. Excess moisutre in the gas stream can indeed lower the heat energy value delivered to your home. After all they are supposed to be selling you gas,not water..right?

So for decades ,,even since nationalised gas industry days, the network operators have been required by regulators to ensure that the supplied gas has the lowest possible amount of H2O in it.

There were regulator tests and measurements done all over the UK to sample and analyse gas to ensure the customer got what they paid for.

In 2004 your great industry regulator and champion of the people OFGEM decided to issue a consultation document the end result of which was the cessation of that long established testing regime.

https://www.ofgem.gov.uk/ofgem-publications/40879/9141-28904.pdf


Why did they do this?

Well it depends how cynical you are.

Bottom line,,if there are no measurements then consumers can be sold gas with excessive moisture content and they will be non the wiser.

Also ,,if no measurements are taken then there is no need to expend money in correcting causative issues in those areas affected.

If no money is spent,then OFGEM can claim they have saved the consumer money.

Where does the water come from?

A multitude of sources but mainly due to ground water ingress into the many thousands of Km of older metallic mains and also ingress into small leaks.

So bottom line,you could well be being sold water and gas and you would be non the wiser as no one is measuring it any more thanks to OFGEM.

analyst_2

macman wrote: »

Isn't the CV primarily determined by the amount of water in the gas?

Thanks for that, but I propose an easy solution.

Just heat the gas before you use it and burn off the water to vapour . . .

No, wait a minute . . .

Uxb

Old style town gas from before the 1970's had a much lower calorific value
So more cubic feet of it was required than from natural gas for the same energy delivered.
So old large houses which were on gas usually have some seriously large diameter pipes feeding the property - just to get the required volume flow rate in.

C_Mababejive

The public could be being sold excess water vapour via their gas meters and they would be non the wiser as OFGEM are not now checking. How would it be if you went down the petrol station, bought ten litres of unleaded and then the assistant came along with a waering can and tipped half a litre of water in your tank and demanded you pay for it?

oldtrout

Thanks for the replies ... oooh, you all sound such clever people.