Making sense of LPG running costs £/kWh calculation {Merged}

10 Posts

Hi,
Was hoping someone could help me understand where I'm calculating this wrong.
I'm trying to figure out the £/kWh of LPG.
Many references on the internet state around £0.07/kWh (7 pence) for LPG, which sounds reasonable.
However, the average cost per litre of LPG is around £0.50/l, which is around what we pay.
- 1 litre of LPG / 3.85 = 1m3
- so 1m3 of LPG = £1.925 (based on £0.50/l)
- 1m3 * 1.02264 (correction factor) * 46 (LPG calorific value) / 3.6 (conversion) = £/kWh
- so 1m3 = 13kWh
- £1.925 / 13kWh = £0.1471/mWh
£0.1471/mWh is more than double £0.07/kWh......??!? So where is my maths going wrong?!
Was hoping someone could help me understand where I'm calculating this wrong.
I'm trying to figure out the £/kWh of LPG.
Many references on the internet state around £0.07/kWh (7 pence) for LPG, which sounds reasonable.
However, the average cost per litre of LPG is around £0.50/l, which is around what we pay.
- 1 litre of LPG / 3.85 = 1m3
- so 1m3 of LPG = £1.925 (based on £0.50/l)
- 1m3 * 1.02264 (correction factor) * 46 (LPG calorific value) / 3.6 (conversion) = £/kWh
- so 1m3 = 13kWh
- £1.925 / 13kWh = £0.1471/mWh
£0.1471/mWh is more than double £0.07/kWh......??!? So where is my maths going wrong?!
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Flowgas suggests it is 95
Calor says it is Propane 95 MJ/m3 & Butane 121 MJ/m3
Unless my maths is wrong (please question it!) it would require an LPG price of 24p/l......is this realistic for anyone in the UK?! ....or is my maths wrong....
"LPG is composed mainly of propane and butane, while natural gas is composed of the lighter methane and ethane. LPG, vaporised and at atmospheric pressure, has a higher calorific value (46 MJ/m3 equivalent to 12.8 kWh/m3) than natural gas (methane) (38 MJ/m3 equivalent to 10.6 kWh/m3), which means that LPG cannot simply be substituted for natural gas."
https://nottenergy.com/resources/energy-cost-comparison/
The sentence you quote has no citation.
But earlier in the wiki article it states (with a citation):
"LPG has a typical specific calorific value of 46.1 MJ/kg compared with 42.5 MJ/kg for fuel oil and 43.5 MJ/kg for premium grade petrol (gasoline).[8] "
As 1kg of propane is about 0.5m3 of gas, a calorific value of 95 MJ/m3 is about right.