Technomad
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Propane contains 7.5kWh/l while Diesel contains 9.7 kWh/l. [1]
That's a %30 difference. At the same time, propane is a heavy gas, and potentially explosive while diesel is rather stable and gives off non-explosive vapors.
I know the RV industry has a whole bunch of reasons for using propane, primarily for cooking, and once you have a propane tank aboard, you might as well use it for heating. Thats fine and so most RVs have propane.
I'm designing my systems from scratch and going my own way in terms of what I chose, mainly to fit my lifestyle (which is, btw, to do sous vide and use the microwave to reheat things, and I'm generally trying to avoid putting a propane tank on my rig.)
In fact, I really would prefer to be completely all electric. I would rather invest in batteries and solar panels (which seem super cheap to me when you get residential units) than in fossil fuels. Not because I'm an environmentalist (I'm not) just because of the nature of burning things in a custom designed vehicle.
I've used a diesel heater before on a boat-- it was a little furnace, and sipped the gas. With a forced air blower on it would have been great. Meanwhile, my experience with a propane furnace in a truck camper is that I would be cold at 3am when the battery ran out. (Though I was probably on the wrong side of the %50 limits for lead acid in those days-- first night I fully depleted the battery and then after that was charing it with the alternator and may never have gotten it back to %100.)
On the other hand, lets figure out the costs per unit of heat:
Propane costs about $2.50/gallon (and has ranged between $2-$3 a gallon for the past 7 years), and Diesel is around $2.95.[2]
Or in short, 8.8 cents per kWh or propane and 8 cents per kWh of Diesel.
I'm assuming that in both systems they are equally capable of converting a liter of their fuel into heat at the same efficiency. Does anyone know the relative efficiency of force air heating with diesel vs propane in BTU/kWh per liter terms?
So propane is only %10 more expensive per kWh and that more than justifies using it if it makes sense for you, while the savings for diesel looked at here are not significant enough to worry about. (but this also puts someones complaint about "don't pay road tax to heat your space" into perspective- I bet that %50 of the cost of diesel per gallon is taxes of various forms, and that the percentage for propane is a lot closer to %10.)
Which brings us to other factors:
-- Overall system performance. Is one more effective than the other? In both cases you can get on demand hot water, hydronics systems and forced air heating.
-- Operational Risk -- eg: in an accident, or results of a leak
-- Quality of the results - Not sure if there can be a difference here, forced air heat should be the same quality since in both cases.
When designing your own system what did you choose and why? I started this post thinking the economics heavily favored diesel, and that the safety factor did as well. Turns out I was wrong on the economics. I still worry about how I will mount a propane tank on my box truck... while I think a small diesel tank in an underbody box would be perfectly safe (and I'd be comfortable with that.)
Thoughts?
[1] http://hypertextbook.com/facts/2006/TatyanaNektalova.shtml
http://hypertextbook.com/facts/2002/EricLeung.shtml
[2] https://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=W_EPLLPA_PRS_NUS_DPG&f=W
https://www.eia.gov/petroleum/gasdiesel/
That's a %30 difference. At the same time, propane is a heavy gas, and potentially explosive while diesel is rather stable and gives off non-explosive vapors.
I know the RV industry has a whole bunch of reasons for using propane, primarily for cooking, and once you have a propane tank aboard, you might as well use it for heating. Thats fine and so most RVs have propane.
I'm designing my systems from scratch and going my own way in terms of what I chose, mainly to fit my lifestyle (which is, btw, to do sous vide and use the microwave to reheat things, and I'm generally trying to avoid putting a propane tank on my rig.)
In fact, I really would prefer to be completely all electric. I would rather invest in batteries and solar panels (which seem super cheap to me when you get residential units) than in fossil fuels. Not because I'm an environmentalist (I'm not) just because of the nature of burning things in a custom designed vehicle.
I've used a diesel heater before on a boat-- it was a little furnace, and sipped the gas. With a forced air blower on it would have been great. Meanwhile, my experience with a propane furnace in a truck camper is that I would be cold at 3am when the battery ran out. (Though I was probably on the wrong side of the %50 limits for lead acid in those days-- first night I fully depleted the battery and then after that was charing it with the alternator and may never have gotten it back to %100.)
On the other hand, lets figure out the costs per unit of heat:
Propane costs about $2.50/gallon (and has ranged between $2-$3 a gallon for the past 7 years), and Diesel is around $2.95.[2]
Or in short, 8.8 cents per kWh or propane and 8 cents per kWh of Diesel.
I'm assuming that in both systems they are equally capable of converting a liter of their fuel into heat at the same efficiency. Does anyone know the relative efficiency of force air heating with diesel vs propane in BTU/kWh per liter terms?
So propane is only %10 more expensive per kWh and that more than justifies using it if it makes sense for you, while the savings for diesel looked at here are not significant enough to worry about. (but this also puts someones complaint about "don't pay road tax to heat your space" into perspective- I bet that %50 of the cost of diesel per gallon is taxes of various forms, and that the percentage for propane is a lot closer to %10.)
Which brings us to other factors:
-- Overall system performance. Is one more effective than the other? In both cases you can get on demand hot water, hydronics systems and forced air heating.
-- Operational Risk -- eg: in an accident, or results of a leak
-- Quality of the results - Not sure if there can be a difference here, forced air heat should be the same quality since in both cases.
When designing your own system what did you choose and why? I started this post thinking the economics heavily favored diesel, and that the safety factor did as well. Turns out I was wrong on the economics. I still worry about how I will mount a propane tank on my box truck... while I think a small diesel tank in an underbody box would be perfectly safe (and I'd be comfortable with that.)
Thoughts?
[1] http://hypertextbook.com/facts/2006/TatyanaNektalova.shtml
http://hypertextbook.com/facts/2002/EricLeung.shtml
[2] https://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=W_EPLLPA_PRS_NUS_DPG&f=W
https://www.eia.gov/petroleum/gasdiesel/