I know that this is getting even further away from moulded fiberglass travel trailers, but I'd like to take the energy source issue a bit further, but tie it back to our trailers...
Often, the choice of energy source is straightforward availability
: if boondocking
in a trailer, propane
is the only reasonable energy source to heat water (and air, and food), so that's what is usually used. In a house without gas service, electricity is the obvious choice for all energy needs. In either case, factors such as cost and efficiency aren't really issues.
is another important factor. If you're already plugged in, electricity just appears when it's needed, with no pilot lights
, valves, etc.
I already mentioned efficiency
. There's no question that the most efficient way to get heat is not to make it into electricity and back again. For fans of hydroelectric, wind, wave power, or any other source of electricity, I'll point out that as much power as is available from these sources is used; each additional bit of electrical
energy that someone wants is produced by burning more coal, oil, or natural gas, or by running a nuclear reactor more.
is a relative thing: if you're already paying for a powered campsite, the electricity is "free", no matter what it costs the campsite operator. Propane
is cheap, but doesn't seem like it at the moment you're taking a tank for refill.
So realizing that there are all sorts of good reasons for specific choices, there is still the question of the actual cost of energy
. Unless I have missed some important piece of information or made a calculation mistake, it seems to me that electricity - even in southern California - is much more expensive than natural gas. Here's my reasoning:
Los Angeles Water and Power says their current electrical charge
is about ten cents per kilowatt hour (US$0.10/kW-h), which is 3600 kilojoules (3600 kJ) - the Joule is the basic unit of energy. So a buck buys about 36,000 kJ, which is 36 megajoules (MJ).
PG&E charges about $1 per therm, and a therm is 105,500 kJ, so a buck buys about 100,000 kJ, or 100 MJ.
So one buck spent on energy buys 36 MJ of electicity or 100 MJ of natural gas
; to me, it's surprising how close they are, but even with some allowance for errors, and perhaps 80% efficiency in a gas water heater (versus almost 100% in an electric demand water heater) it seems that gas is significantly cheaper. Again, maybe I took a wrong turn somewhere and got the wrong result.
In a trailer, availability and convenience rule, but I think it makes sense to keep efficiency and cost in the back of the mind. At home, the balance is different. Either way, it's up to each of us to make the choice which is right for our situation.