Carbon footprints, heating, and firewood

firewood

Our new home has a fireplace, and we just had a cord of wood delivered. They brought it in a small dumptruck, emptied it in the driveway, and while stacking it (hey, a cord is a LOT of wood to stack, 4x4x8, to be exact) was thinking about carbon footprints.

Firewood is a renewable resource, yet it leaves a carbon footprint when burned for heat. Hundreds of millions if not billions of people probably do this every day too.

However, a carbon footprint also has to take into considerable how the fuel source was prepared, and in that, firewood has a tiny footprint compared to natural gas, electric, or heating oil. The carbon produced by log cutting machines and chainsaws is miniscule compared to that of processing crude oil into fuelstocks. And of course, in many parts of the world, most if not all of the wood cutting is done manually, so there’s no footprint at all.

I wonder what the carbon footprint of burning wood in a fireplace is compared to, say, a heating oil furnace, as is common here in New England?

26 Comments

  1. Something to consider: the creation (i.e. growing) of firewood actually absorbs CO2. Promoters of wood-fueled Dendro power plants claim the absorption is greater than the carbon produced in burning. I wish I could corroborate that, as I too burn wood for heat.

    Something else to consider: a fireplace is a very inefficient source of heat. The efficiency improves greatly if the fireplace was built with a “heatilater,” which allows air to be heated by passing behind the firebox. But even then, fireplaces cannot compare with a good woodstove for efficiency. It’s fairly easy to fit a stovepipe to a chimney, and the stove then sits in front of the fireplace (on a fireporoof surface such as stone). For those who would miss seeing the flickering flames, fear not. There are some very good stoves that have glass fronts.

  3. Both dj and Eli have good points, and there’s more to the analysis as well. I don’t know what the answer to your question is, but we can at least outline the parameters.

    Dj is quite right about the inefficiency of fireplaces. It can be solved: friends of my family in Wisconsin lived in an 1840’s stone cottage in Mineral Point. I think Jesse told me that it took him 4 or 5 cords to get through the winter, for which figure November to February. They had a Franklin stove in the main room which they kept going all the time. The stove had a long pipe–about the length of the house– which heated the air where they lived/slept. There was a downstairs that had the kitchen and root cellar, and I seem to recall that it was dug into the side of the hill and below the frost line. I was only there in summer, but I recall that they had a separate Franklin stove in the kitchen for supplemental heat.

    Now, none of this was terribly convenient. They left home only at their peril, and to prepare the meals, one of them had to get up at 5 and stoke the stove downstairs so it wouldn’t be frigid. And they consumed a lot of wood.

    Wood is much less combustible than oil and has a lower heat output per unit of equal weight. Thus, you will have to burn lots more wood to get the same heating effect as burning oil. Not necessarily a strike against wood, but a consideration.

    Eli has mentioned the particulate matter in woodsmoke. Anybody who’s even sat through a California campground where everybody and his brother lights a fire–oooh, it’s so cool to have a campfire!–knows the problem first hadn. Remember that “smog” was coined as a combination of “Smoke” and “fog” when there were lots of wood and coal fires in England.

    Moreover, you’re not emission free. If you burn oil with complete efficiency, you’ll get carbon dioxide and water vapor. Of course nothing is efficient, which means you can get ozone, nitrous oxides, carbon monoxide, unburned hydrocarbons as well. If I recall the chemistry right, a wood fire probably doesn’t produce nitrous oxides and ozone (usually produced in cars, not furnaces), but it sure has lots of unburned hydrocarbons, carbon monoxide, and, best of all, CO2. Oh, yes, that wonderful greenhouse gas! So although you may not have a lot carbon EXPENDED in getting wood to you, it’s not like you’re using electricity generated by solar, wind, or nuclear (yes, I know nuclear has other problems, but a carbon footprint is not one of them) with relatively few by0products as a reustl fo burning it.

    And, frankly, I’m not sure what the real carbon footprint of delivering natural gas or heating oil really is. Those hydrocarbons pack a lot of energy per unit volume, lots more than wood. They move either by pipeline or by tanker, which is amazingly efficient considering the BTU’s burned. Your wood is moved by truck, I would assume, which is far less efficient. Don’t know what the numbers are, but I wouldn’t be surprised to find that the carbon footprint for delivering your wood to your driveway isn’t all that much less than delivering a comparable number of BTUs in gas or oil, simply because of the economies of scale and great heating efficiencies.

    Another consideration goes beyond carbon, which is whether burning wood is in any way sustainable. A cord of wood has to be at least a mature tree, so if lots of people are going to be burning wood instead of oil, we need to figure out how much wood they’ll be burning, and how many trees are needed. I’d bet that if all residences…well, let’s say single-family homes, since I can’t imagine office buildings or apartments heating by wood….in Connecticutt burned only wood, there wouldn’t be enough trees naturally occurring in COnnecticutt to keep up with the demand. Deforestation is a serious problem, even if it happens in New England. We have all sorts of problems demonstrated in the historical record, from mainland archaic Greece to the Anaszai to the Himalayan folks who have deforested huge swaths of forest for fireword for heating. Oh, add to that the forests of England, though they were cut to provide charcol for the early foundries. So there can be perifpheral problems of wood use as well.

    An alternative is to create forests designed to be cut for firewood. I confess that I don’t know that much about tree plantations, but I understand that plantations in general are not partiuclarly sound ecologically because they become monocultures and reduce the variety of species to a point where the area becomes susceptible to ecological shock. Jared Diamond did a nice job of showing how the timber industry is now suffering in Montana after it was one of the leading industries in the state, severely damaged by unsound plnatation and other practices.

    Like I said, I don’t know the answer to all of these questions, but they’re the kind that should be raised.

  4. My sister’s boyfriend is an environmental engineer, and he said wood fires produce “nox” which I assume is nitrous oxide as well as other bad stuff.

    More and more what I’m coming around to is that the real problem is too many people live on the planet.

  6. “NOx”, where the “x” should be a subscript, is the shorthand for any kind of nitrogen oxide, inlcuding NO, No2, N2O and lots of other noxious products that react violently in oxygen environments and chew up hydrocarbons and are produce free-radical chain reactions (think “plastics being form in the air”). Car engines certainly get hot enough to produce it in pressureized condition; I didn’t know that wood fires did as well. Your fireplace could be dirtier than a 1966 V12 Cadillac, then, in terms of the pollution it puts out.

  7. We burn wood in a small jotul box stove; have an Ashley type in the basement for emergencies. Also have an oil fired 20 year old furnace. Tightly insulated house, etc. I cut the wood off our 3 acres with a chain say, haul it manually or with a motorized wagon, split it by hand, etc. So I’m guessing that the carbon footprint of the acquisition process is nearly nil. The jotul stove meets particulate EPA standards and reduces our consumption of fuel oil by 40-50%, nearly 300 gallons. Must be a net improvement I would think particularly when the renewable aspect of our small woodlot is considered.

  8. Some of the concerns raised are addressed with newer wood stoves. My wife and I heat exclusively with wood. We bought a house with electric baseboard, but had a Quadrafire stove installed into an existing fireplace box, with triple insulated steel as a chimey up through the existing one. We also put a smaller one in our bedroom– a soapstone parlor stove.

    Both of these stoves are secondary combustion meaning that many of the harmful gasses are actually ignited in the box before being released into the environment. Eyeballing the color of the smoke should indicated what is going on: ours do not emit any smoke — only the shimmer of heat. Most new, good quality stoves are 70, or 80, some up to 90% efficient, as opposed to fireplaces that are about 20% efficient. Some fireplaces actually lose more heat up the chimney then they generate for the home. Secondary combustion or catalytic converters ensure are not only better for the environment, but are much more efficient in terms of heat return.

    Deforestation is not required to heat with wood. The amount of already-down wood on private and public lands is much more than enough to keep up with heating needs. We go through about 4-5 cord of wood per winter in central pennsylvania. We live on four wooded acres, and we cannot keep up with the splitting of the wood that naturally sheds — downed trees in storms, shedding limbs and branches. We have enough for many years to come without taking down a single healthy tree. Evidently, at about 4-5 cord burned per year it takes just a few acres of land to reach this balance. In some states (PA included) you can buy a license for $10 to harvest downed and dead wood from state lands. It doesn’t get much more cost effective to heat a house, and if you are following responsible burning practices (i.e., not putting plastic in your stove) and you buy a new stove with secondary combustion or a converter, you have a nice way to heat your house cheaply and are leaving virtually no carbon footprint behind.

  9. Hi – I haven’t seen any discussion relative to what happens to the tree once it dies. I was led to believe that the process of decay provides some element of C02 release that is on the same order as what is produced in a clean wood fire – not sure of the chemistry but this detail offsets the carbon footprint if the wood were left to rot rather than get burned.

    For harvesting wood for fuel, one acre can produce one net cord of wood per growing season in the New England area. This assumes that the limbs are harvested as well as the main trunk. I believe that wood head is a supurb use of converting solar resource directly to useable heat for those of us willing to partake in the labor of harvers

  10. Wood does release CO2 as it decomposes– but of course that happens over many years. I grew up in New England in the 1960s, where downed trees from the Great Hurricane of 1938 still lay partially decomposed in the woods.

    While the trees stand– and until they decompose– they act as a temporary carbon sink. But selective removal of trees makes room for new trees to grow (and existing trees to grow larger and healthier). Thus, unless it is overdone, firewood is a reasonable way to convert solar energy to heat. The smoke would cause significant ptroblems in populated areas, however.

    There is some evidence that particulate pollution helps reflect the sun’s heat back out of the atmosphere, helping to prevent global warming. That doesn’t mean I think everyone in NYC should clear cut forests and fill the air with smoke!

  12. Hi Folks,

    I pose this question anywhere, to anyone preoccupied with the notions of co2 as always bad–of course not true,we as humans are carbon. Anyhoo… My question; and I warn you, the question will ask you to possibly consider you changing your outlook 100%…

    Suppose that co2 is a byproduct in our environment from warming?…and warming NOT a byproduct of co2? That is to say, that warming is producing the co2, and not the co2(anthropogenic or natural) causing warming. The warming being a completely natural, uncontrollable occurrence. It can’t be difficult to believe this knowing that our climate history has shown we’ve been through very strong warming periods in the past (medieval warming period) What caused this warming??…man made greenhouse gases/co2 ? No, it was cyclical and natural. Seriously consider watching a British film called “the great global warming swindle” It was very enlightening.

  13. I don’t agree that product of burning of wood produces “nox”. Products of burning of wood are water (H2O) and carbon dioxide (CO2). Usually they are base matters. I don’t think CO2 is so dangerous.. except greenhouse effect, of course.

  14. WELL IT IS GREAT TO READ ALL THE SCIENTIFIC AND PRACTICAL APPLICATIONS FOR WOOD BURNING FOR AND AGAINST. I HAVE INSTALLED CODE SPECIFIC WOOD BURNING FIREPLACES HERE AT LAKE TAHOE, VERRY EFFICIENT AND NEAR ZERO EMISSIONS, BUT I MYSELF REMOVED THE WOOD FIREPLACE IN THE SMALL CABIN I RENT ON THE NORTH SHORE OF LAKE TAHOE. THIS IS TAHOE DIRTY SECRET AND ITS NOT SO LITTLE. WE ENTERED THE WINTER SNOW SEASON JUST LAST WEEK BUT FOLKS HAVE BEEN USING THERE WOOD STOVES, INSERTS AND FIREPLACES FOR MONTHS NOW BECAUSE OF THE COLD TEMPERATURES. ON MY STREET ALONE THERE ARE NINE OUT OF TEN HOMES THAT USE WOOD, ME BEING THE NON WOOD USER AND MANY, OVER HALF OF THE MOBILE HOMES ONE HUNDRED YARDS AWAY USE WOOD IN THE TRAILER HOME. IN THE EVENINGS AND ESPECIALLY IN THE MORNING THE AIR IS RANCID AND HEAVY WITH THE FINE PARTICLES OF POLLUTANTS ENVOLVED WITH WOOD BURNING. IT IS TOUGH AND IRRITATING TO SHOVEL AND BREATH THE TAHOE AIR IN MY NEIGHBORHOOD UNFORTUNATELY. SO THE DIRTY LITTLE SECRET TO ME IS SO MANY DO NOT OR WILL NOT DO THEIR PART TO KEEP THE AIR CLEAN IN THEIR OWN BACK YARD (nimby) AND WHEN ENGAGED IN THE OBVIOUS DECUSSION A BOUT THE POLLUTION COMING OUT THERE CHIMNEY THE RIGHT TO BURN WOOD IS THE FIRST EXCUSE/REASON EXPRESSED ALONG WITH ECONOMIC REASONS BUT RARELY ANY PERSONAL ACCOUNTABILITY TO EVEN OUR LOCAL OR REGIONAL POLLUTION. I AM NOT KIDDING YOU WHEN I SAY IT IS TREMENDOUSLY ANNOYING AND DIFFICULT TO DO AN HOUR OF SNOW SHOVELING WITHOUT WEARING A NUISANCE MASK OR HEAVIER PROTECTION AND THE JUXTOPOSITION IS THIS IS SUPPOSED TO BE ONE OF THOSE JEWELS IN THE SIERRA MOUNTAINS.

  15. Burning wood is inappropriate for heavily-populated areas because of the tendency of particulate pollution to accumulate.

    But for sparsely-populated areas like ours, there’s little enough that nature brings it back to earth. With my neighbors a half mile away, I can’t even smell their stoves (they have two) when the wind blows the smoke in our direction.

  18. Wood smoke (particulate matter) is one of the most carcinogenic pollutants in the air we breath. On any given day from fall through spring the air outside our home is thick with smoke from our neighbors fireplaces (and we live in sunny Southern California). Even when we stay inside to avoid this pollution, the smokey air gets into our home. Our patio furniture outside gets covered with black soot. This is the same black soot that gets into your lungs and causes lung diseases including cancer. The people who burn wood in their fireplaces are at ground zero, they are harming their own health and most don’t even realize it. There is a high incidence of people, particularly women, who have never smoked being dx’d with lung cancer, most likely caused by second hand smoke and environmental air pollution. Do any of you who burn wood ever go outside and look at the pollution you are creating?

  19. Are you sure that soot isn;t from the airport? My car gets covered in it year round.

    OTOH, it IS true that wood smoke contains carciunogens. So do vehicle exhaust and barbecued meat. The good news for fireplace users in rural areas is that with a clean flue and dry wood, the smoke goes up the chimney and exposure is minimal.

  22. We live in northern Washington State and heat with a wood stove. We have 5 acres, 3 of them cleared. The other 2 acres grow faster than we can harvest them for wood – we are trying to thin to encourage biomass and are falling behind.

    I do not understand the comments that talk about the smell of smoke. Maybe people are heating with fireplaces? If you use dry wood (here, that means harvested the previous spring or earlier) and start with a brisk kindling fire, then damp it down to a very slow fire, the only smoke that you can see or smell comes from the first couple of seconds of burn. That’s because the firebox isn’t hot yet and the flames have not yet found all the paper and twigs. Once they are alight, the fire burns clean and stays that way even when you add more DRY wood.

    • Oh, and we also coil our hot water pipes around the firebox to get “free” hot water in winter. And, it’s a cookstove so we do all our cooking on it, in winter.

    • I think it’s more that the particulate matter emitted by burning wood in fireplaces is really nasty and toxic, according to my brother-in-law, who is an environmental engineer.

      Thanks for the tips, coiling the hot water pipes around the wood stove is a great idea.

      • The particulate matter is bad to breathe– but it doesn’t stay airbiorne long. Again, wood makes sense in rural areas, but not in most ‘burbs.

        We have an old (1940s) wood cookstove that includes a water heating element. We hooked that to a radiator to increase our heat output. And it’ll burn either wood or coal.

        Believe it or not (do the math!), bad as coal is for the environment, burning coal for heat is more environmentally friendly than using electric heat. That’s because 50% of America’s electricity comes from coal to begin with– and to heat with electricity, you have to convert coal to heat, heat to steam, steam to motion, motion to electricity, transmit electricity hundreds of miles through wires, and then convert electricity back to heat. With losses at every step.

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