The Zero-Emissions Challenge, Part 3: Heating
The next obvious source of emissions is heating. It's only an issue three months out of the year, but it's a big one: last year, which was unusually cold, we spent as much on electric space heating as we did for all other electric usage for the entire year. But electric is not our only source of heat. We heat with propane, wood, electric, and passive solar.Passive solar is essentially free. Built of brick, our home absorbs heat during the day and stays warm at night, so during the spring and fall we rarely have to use space heat at all.
Our home furnace, hot water heater, dryer, and range all use propane. It's difficult to estimate our usage since we get filled only twice per year, but it appears that we go through about 300 gallons each year, of which about half goes to space heating. Propane contains about 91,500 BTUs per gallon, so that's about 14 million BTUs per year. Add to that about 44 million BTUs of electric space heating and roughly 60 million BTUs from wood. That's almost 118 million BTUs per year from non-passive sources!
The good news is that the wood we burn is almost carbon-neutral. First, what we use in the stove was already dead when we cut it— we don't kill any trees in the process, and in fact we make room for new trees to grow. (Why would you cut green wood for the stove anyway, when it doesn't burn as well?) Second, the burning of the wood is considered carbon-neutral because (1) the carbon released is equal to the carbon the tree absorbed over its lifetime, which the carbon a replacement tree will also absorb, and (2) the CO2 released in burning is equal to the CO2 that would be released if the tree decomposed in nature. (See The Green Guide on this. Particulate pollution is a seperate issue, but in rural areas the impact is minimal.)
I say our wood is "almost carbon neutral" because we have to haul our wood an average of 20 miles in the pickup and cut it with a chainsaw. By my estmate, this adds 2.6 gallons of gasoline per cord, or 52 pounds of CO2 per cord, or about 3 pounds of CO2 per million BTUs. That compares with about 142 pounds of CO2 per million BTUs from propane or 439 pounds per million BTUs of electricity from the grid. Clearly we'd reduce our impact greatly by switching as much as possible to wood and solar.
Using the "easy method" I described in my last post, not making any major investments ir lifestyle changes, we could cut our emissions significantly with several simple approaches. First, we'd burn more wood and less propane in the house. We already did that last year, rarely raising the thermostat above 58. Being an unusually cold winter, we still used some propane, but I think we can reduce it close to zero this year. Second, we now have a usable woodstove in the barn, an old 1930s wood-fired cookstove. Unless it's very cold, we don't need to heat the barn, but when it hits -30, we need to keep animals, water pipes, and stored liquids from freezing. We also plan to install insulation before winter hits, as well as increase the passive solar heating by making a few simple upgrades. But on those exceptionally cold nights, we'll use wood instead of electric.
There are two areas that would require major capital investments to significantly reduce our heating. First is the pump house, a small structure a few yards away from the main house. It's insulated, but not very well, and there are cracks through which cold air enters. Caulking and insulating can remedy those. But here's the challenge: the pumphouse cannot be allowed to freeze, or we have no water. Last winter, during a power failure, the wellhead froze and left us without water for a week. Up to now, we've used an electric heater on a thermostat, which we'll still use as a backup (now supported by a battery backup charged by our solar panels). But how to find an alternate source of heat? The ideal solution would be a solar hot water heater, which would easily hold heat for several days and prevent the pump house from freezing under almost all conditions. But it would cost several thousand dollars. A less suitable but far more economical solution would be a passive solar air heater installed on the south wall. On sunny days, at least, this would raise the interior temperature during the day, significantly reducing but not eliminating the need for electric space heat.
The second big challenge is the bathroom, which is the room farthest from the wood stove. When it's 50 degrees in there, taking a shower is less than pleasant. (And even if I was willing, my wife isn't.) Once again, our solution until now has been electric space heating. The only alternative I can think of is a hot water heating system run through the floor tiles. That would cost several hundred dollars to install, and would require replacing the floor tiles. The good news is, we need to replace them one of these days anyway.
Bottom line: we can't completely eliminate our emissions from heating, but we can reduce them a lot. My estimate is, by switching to wood and solar as much as possible, we could reduce our emissions from about 21,868 pounds of CO2 produced each year to about 1,500 in a normal year using the "easy method." (Emergencies and unusually cold weather would still require alternate heat sources.) By implementing the "planned method" and spending about $5,500, we could reduce to about 260 pounds of CO2 per year. Now that's a reduction.
Did you consider geothermal heat pumps for heating and cooling? They reduce electric consumption and eliminate natural gas bills.
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[Abusive phrase deleted.] To think that burning wood is almost carbon neutral and imply that it may be environmentally good it leaves me almost speechless. I was a former wood burner having grown up on a farm and lived that life for many years. No one wood (no pun intended) describe me as a tree hugger yet I truly respect the environment and other human beings. I will not ramble on about the dangers of burning wood. The logic of this writer is so skewed. Google all the info you need on wood burning and propane use and you will soon realize that these are, short of burning truck tires two of the worst ways to heat your home. Do the research and the math solar and geoexchange which is basically passive solar are the way to go. Sorry about the comment sometimes I have a visceral reaction to environmental stupidity
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Compared to solar and geothermal, you're right-- but at present, heating with these is not within our budget. We use some passive solar, and are working on some basic geothermal improvements. We also have a 1Kw solar array, but it isn't enough capacity to heat with. The cost of enough solar panels and batteries to keep our home from freezing in winter would exceed $130,000-- and even then, we'd need some kind of backup for periods when the sun is obscured by clouds. We could add wind (at a cost of about ($40K for a 5 Kw system installed), but again we'd need backup because (like now) sometimes the wind doesn't blow for days. I think solar/wind self-sufficiency is a great idea-- but in cold climates, it's primarily for the wealthy.
On the other hand, to say that wood, which recycles the same carbon over and over, compares unfavorably with, say, coal-generated electricity or natural gas, both of which take "new" carbon out of the ground and put in into the air, seems a bit shortsighted. (I didn't choose propane-- it's what the house came with.) I'm talking here strictly about carbon-- particulate pollution is another matter, one which varies in severity according to population density, and which some recent studies suggest impedes global warming, though I won't rely on that as a justification.
Is wood perfect? Absolutely not. We're working on imprivements as we can afford them. But for those of us on a budget (and there's no heat cheaper than wood at $5 a cord), it's an improvement over the traditional alternatives. Or perhaps you'd like to make a financial contribution to enable us to implement cleaner technology more quickly?
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