Anyone know oil kWhr and boiler efficiency figures?

[mtoner]

Hi,

I'm trying to compare oil with other energy types and I'm having problems getting a definitive answer on how many kWhr 1 litre of oil produces.

At first I thought it was 11.69kWhr for each litre of oil as listed here:
http://www.carbontrust.co.uk/resource/e ... efault.htm
but then I found a report dated Jan 2008 which listed it as 10.18kWhr
http://www.sei.ie/getFile.asp?FC_ID=3432&docID=645

I had also assumed 90% oil boiler efficiency but this report suggests 60% to 70% efficiency. It makes a big difference if, say, you are trying to work out how long solar panels would take to pay off at current oil prices.

Any feedback on this would be appreciated.

Thanks
Michael

[MacG]

It makes a big difference if, say, you are trying to work out how long solar panels would take to pay off at current oil prices.

Any feedback on this would be appreciated.

Thanks
Michael

I think it's a mistake to believe that the price of oil will stay at today's extremely low levels. Increasing oil prices will most probably mean increased prices on solar panels also.

My feedback is thus: Buy ANY solar panels you can get your hands on NOW. The effect will be that when using the panels 30 years from now, you will be subsidized by today's cheap oil.

[tomhitchman]

here is something that both defines the relationships between BTUs kwhs, joules etc and the amount of energy in different fuels. Hope it helps.

http://www.teesforest.org.uk/R&Renergy_conv.htm

[mtoner]

Can't see what I'm looking for but thanks.

It seems adsurd that there are two figures (10.18kWh and 11.69kWh) doing the rounds for how much energy a litre of oil produces (before boiler inefficiencies) especially since that figure will obviously form the basis of multiplications in thousands unless I'm missing the meaning of gross calorific value?

[tomhitchman]

In fossil fuels towards the bottom it has :

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Barrel of oil equivalent (boe) = approx. 6.1 GJ (5.8 million Btu), equivalent to 1,700 kWh. "Petroleum barrel" is a liquid measure equal to 42 U.S. gallons (35 Imperial gallons or 159 litres); about 7.2 barrels oil are equivalent to one metric tonne of oil = 42-45 GJ.

So 159 litres in a barrel of oil [1700 kwhs] gives 10.69 kwhs a litre.

It goes on to say that not all products of oil are the same density which is where the differences might lay:

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N.B. the energy content (heating value) of petroleum products per unit mass is fairly constant, but their density differs significantly ? hence the energy content of a litre, gallon, etc. varies between gasoline, diesel, kerosene.

[mtoner]

Sorry - I should have been more clear but I think you've found where I've went wrong. Thanks tomhitchman.

I'm considering kerosene only and I think the 11.69 figure doesn't apply to kerosene.

Here's some variations for what 1 litre of kerosene should produce:
10.22 http://www.entech.co.uk/entech/ener_conv.htm
10.18 http://www.sei.ie/getFile.asp?FC_ID=3432&docID=645
and others seem to hover around the 10.18 make so I'll go with that.

On boiler efficiency, I'm going with
90% efficiency for a condensing boiler
75% efficiency for a non-condensing boiler
Probably optimistic by about 2% to 5% but if you have a crap boiler, like I have, and given the massive upward climb of oil then its certainly worth considering a better boiler if you're sticking with oil.

Thanks again,
Michael

[RogerCO]

A bit anecdotal but I've got the spreadsheet to back it up. I replaced an old oil boiler with a new one about 5 years ago - same manufacturer and model (Worcester HeatSlave) but latest version and got an immediate 18% reduction in oil consumption. (measured over a period of a year each side of the change with no other significant changes in either lifestyle or house energy efficiency.

[kenneal - lagger]

Hi! Michael

You can get individual boiler efficiencies from this database

http://www.sedbuk.com/

There can be quite a difference between boilers even from the same manufacturer so it's worth looking up.

Getting the correct size boiler can make a big difference in its efficiency as well. An oversized condensing boiler might not condense, for instance.

It's the official one we use for calculating SAP ratings.

Ken

[mtoner]

Thanks everyone.

Didn't know about the boiler efficiency database or even that replacing the same model (old for new) could make such a difference. 18% is alot of money these days and I know, for myself, that my boiler is non-condensing so it could go higher.

Its certainly something I'll be looking into for further comparisons.

Michael

[RenewableCandy]

Yes but get any insulation work over and done with first, so the boiler ends up the right (small enough) size (and probably cheaper to boot)

/thebleedin'obvious

[RogerCO]

. 18% is alot of money these days and I know, for myself, that my boiler is non-condensing so it could go higher.

I would treat my 18% with caution - it was a pretty old boiler and had probably been performing sub-optimally for more than a year (ISTR when we took it out we found that the flue baffles had collapsed so a lot more heat was going up the chimney than intended). You might like to consider moving away from oil - starting new thread on this...