Costs: LPG vs Electricity. (1 Viewer)

scotjimland

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Being on metered electric I wanted to calculate if it was cheaper to run appliances on LPG rather than electric, fridge, water heater, etc.

I used this info for the calculation:
1 Gallon of LPG = 27 kWh (Kilowatt Hours) of electricity

LPG costs ~ 50p lt.
1 lt equal to 6 kw
so 1kw costs 8.3p

Electric costs 16p kw

So LPG is ~ half the cost of electricity (assuming appliances are equally efficient on either fuel.)

Have I calculated correctly.. ?
if so then LPG wins hands down until it reaches £1 per lt.
 

Snowbird

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Hi,dont know if this is any help with your calculations but when overwintering in Spain I found it much cheaper to run the fridge freezer on gas.I also put a switch on my charger so that I can switch it off when not neaded to charge batteries,I never had to switch it on yet,with the solars.If your RV is a UK conversion I was told the converter uses quite a lot of power,but I dont know cos I dont have a converter becouse mine was imported new with no 110 volts in it.I do know that the US fridge freezer uses a lot of electric and seems to be more efficient on gas.Hope this helps,Dave.
 
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scotjimland

scotjimland

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If your RV is a UK conversion I was told the converter uses quite a lot of power,but I dont know cos I dont have a converter becouse mine was imported new with no 110 volts in it.I do know that the US fridge freezer uses a lot of electric and seems to be more efficient on gas.Hope this helps,Dave.

Hi Dave

Indeed it does, the 230/110v tranny uses power even when not in use , I did a post about this some time ago ..

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cheers

Jim

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Braunston

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Hi, Jim

I think your end result is true that LPG is cheaper to use than Electricity at the rates you are paying, but i think you need to add a few items into your equation

Delete:- LPG i would suggest on the fridge is at best 70% efficient, so on your calculations the kW rate goes from 8.3p to nearer 11.8p xxxxxxxxxxxx

You also need to factor in transport costs for the LPG i.e. road fuel costs to and from the LPG filling station.

hope that helps

Edit
Hi, Sorry messed that up forget the 70% etc as that has no bearing on your calculation as i would think you were correct that the efficiencies are very similar, the only part of my thread that bears any point is the transport costs




Being on metered electric I wanted to calculate if it was cheaper to run appliances on LPG rather than electric, fridge, water heater, etc.

I used this info for the calculation:
1 Gallon of LPG = 27 kWh (Kilowatt Hours) of electricity

LPG costs ~ 50p lt.
1 lt equal to 6 kw
so 1kw costs 8.3p

Electric costs 16p kw

So LPG is ~ half the cost of electricity (assuming appliances are equally efficient on either fuel.)

Have I calculated correctly.. ?
if so then LPG wins hands down until it reaches £1 per lt.
 
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Geo

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Your calcs as ever seem correct
You have won me over Jim
Your next mission should you choose to except it is
where can I buy gas mantles for the lights, and a LPG 26" tft Telly:roflmto::thumb:
Geo
 
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scotjimland

scotjimland

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Hi, Jim

I think your end result is true that LPG is cheaper to use than Electricity at the rates you are paying, but i think you need to add a few items into your equation

LPG i would suggest on the fridge is at best 70% efficient, so on your calculations the kW rate goes from 8.3p to nearer 11.8p

You also need to factor in transport costs for the LPG i.e. road fuel costs to and from the LPG filling station.

hope that helps

Hi

Thanks.. your probably correct about the efficiency, but I couldn't find any figures on that .. still quite a saving even at 70%
but on electric I have the losses of the 230/110 tranny to consider .. which probably puts it about even again..

re transportation, I have 2 x 19kg bottles and fill up just down the road using the toad.. so no significant cost there ::bigsmile:

Jim

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scotjimland

scotjimland

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Your calcs as ever seem correct
You have won me over Jim
Your next mission should you choose to except it is
where can I buy gas mantles for the lights, and a LPG 26" tft Telly:roflmto::thumb:
Geo

Funny you should mention gas mantles.. :winky:
was just talking about them other day.. had them in an old van, lovely and cosy ..

TV.. and water pump are more of a challenge :roflmto::roflmto:
 
Jul 29, 2007
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Hi none of that will be a problem if they ever get an LPG fuel cell sorted out at a realistic price just for motorhomers.

Olley
 

Braunston

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Hi,

I don't know what type of bulbs you are using for lighting, but if you want to reduce your fuel?? consumption its really worth looking at the low energy bulbs and now the LED alternatives,

If we could get the unit costs down on the LED bulbs there could be some very real energy savings. I am still looking at trying to make my own

Interesting subject you have started, thanks

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Braunston

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Hi, Brian

As I wrote' if we could get the unit costs down on the LED bulbs there could be some very real energy savings. I am still looking at trying to make my own (LED bulbs)

I have found a number of places that will sell the small plastic dome type LED's at reasonable prices, but i still can't find anywhere that sells the small flat yellow coloured LED's that were being used on the made up bulb replacements at the Peterborough show, anyone know where i can purchase them from would be a help,

You are going to make LEDs - respect !

But I guess you mean building your own modules. You'll not do it if you buy the parts from RS, that's for sure.
 

hilldweller

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anyone know where i can purchase them from would be a help,

Wander round RS and you'll find about 3000 LED hits.

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NOTE: this is just to get you into RS, it's not powerful enough for illumination.

This is but look at the price:
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But don't overlook the switchmode regulator that you need to engineer.

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pappajohn

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im probably totally wrong here....
but my leds look like SMT components (surface mount technology) and are usually assembled by machine as a regular soldering iron is just too damn big.

i bought a load at newark to replace ALL my halogens....£8-ish per unit.....50,000hrs average lifespan.
thats 0.016p per hour purchase cost per unit.
hardly worth the effort involved in making 'em.
 

Braunston

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Hi,

I take your point about the cost/lifespan and it makes sense, but the chaps who were selling them were making them up from components, as in one particular case they didn't have the ones a friend wanted and said they would make them up overnight for him, which they did and he purchased them the next morning

If i had the money I would probably buy them as you did but as I don't that's why I have been asking the question as i would like to know where to purchase the components and see if i can make them within my budget.

As for your suggestion of SMT, I don't know anything about them and you may be correct, however from those LED bulbs that were on sale there did appear to be quiet a number of configurations albeit they were/did appear to all be mounted on minute sized circuit boards.

Can they be purchased ready mounted on differnt sized circuit boards ???




im probably totally wrong here....
but my leds look like SMT components (surface mount technology) and are usually assembled by machine as a regular soldering iron is just too damn big.

i bought a load at newark to replace ALL my halogens....£8-ish per unit.....50,000hrs average lifespan.
thats 0.016p per hour purchase cost per unit.
hardly worth the effort involved in making 'em.
 
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scotjimland

scotjimland

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Hi none of that will be a problem if they ever get an LPG fuel cell sorted out at a realistic price just for motorhomers.

Olley

Hi Olley

Information from Truma would suggest that the leccy would be more expensive than off the grid

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Approximately 30 kWh of electricity can be generated with the contents of an 11 kg cylinder

So 22lt LPG @ 50p = £11 produces 30 kw
Cost per kwh = 11/30 = 36.6p :Sad:

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Braunston

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Just out of interest do you know why the "W" in kWh is capitalised ??

answers on a £20 note to the originator please :ROFLMAO::ROFLMAO::ROFLMAO:


Hi Olley

Information from Truma would suggest that the leccy it would be more expensive than off the grid

Link Removed




So 22lt LPG @ 50p = £11 produces 30 kw
Cost per kwh = 11/30 = 36.6p :Sad:
 
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scotjimland

scotjimland

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Just out of interest do you know why the "W" in kWh is capitalised ??

answers on a £20 note to the originator please :ROFLMAO::ROFLMAO::ROFLMAO:

:winky:

This SI unit is named after James Watt. As with every SI unit whose name is derived from the proper name of a person, the first letter of its symbol is uppercase (W). When an SI unit is spelled out in English, it should always begin with a lowercase letter (watt), except where any word would be capitalized, such as at the beginning of a sentence or in capitalized material such as a title. Note that "degree Celsius" conforms to this rule because the "d" is lowercase.
 

Braunston

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Hi, Jim

Using your original figures it appears that the Truma unit will need to use nearly the equivalent of 4.5kW of LPG to produce 1kW of electricity. that dosen't sound right as if its correct that's an awful lot of fossil based fuel to use to produce just 1 kW of electricity

what do you think ?



Hi Olley

Information from Truma would suggest that the leccy would be more expensive than off the grid

Link Removed




So 22lt LPG @ 50p = £11 produces 30 kw
Cost per kwh = 11/30 = 36.6p :Sad:

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scotjimland

scotjimland

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Hi, Jim

Using your original figures it appears that the Truma unit will need to use nearly the equivalent of 4.5kW of LPG to produce 1kW of electricity. that dosen't sound right as if its correct that's an awful lot of fossil based fuel to use to produce just 1 kW of electricity

what do you think ?

Don't sound right to me either ..

Can someone else double check ?

I got my original info from here Propane Vs. Electricity - A Comparison
 
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scotjimland

scotjimland

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Hi, Jim

Using your original figures it appears that the Truma unit will need to use nearly the equivalent of 4.5kW of LPG to produce 1kW of electricity. that dosen't sound right as if its correct that's an awful lot of fossil based fuel to use to produce just 1 kW of electricity

what do you think ?

Don't sound right to me either ..

Can someone else double check ?

I got my original info from here Propane Vs. Electricity - A Comparison


I've checked again:

To generate 1kW of electricity, the Truma uses 0.73 lt LPG, equivalent to 4.38 kW electric.

if these figures are correct that makes it only 22.8% efficient.

Information about fuel cell efficiencies is hard to find ..

Fuel cells are significantly more efficient than equivalent internal combustion engines (ICEs) because they convert chemical energy directly to electrical current rather than via an efficiency sapping mechanical intermediate phase.

Not much use .. says little , nor does this ..

Fuel cells offer a better way of producing electricity and heat than traditional power generating products. Fuel cells are highly efficient, quiet and produce low emissions - making it possible for everyone to move to a more secure and sustainable energy world.

but I did find this chart comparing the efficiency of fuel cells with diesel and gasoline engines.. rather disappointing I think ..

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