Saturday, January 18, 2014

Remote Cabins: Cost of Heating by Wood

The third element of Maslow's hierarchy is warmth. Obviously, in Alaska, this is a prime concern, because our winters are long. Below is our experience heating with wood, and below that, a comparison of BTUs generated by various heating fuels.

Since we live in the middle of a forest, we decided to heat our cabin with logs that my husband cuts throughout the year. The wood is stored in a huge wood “corral" behind the
My lumberjack with mosquito net
outhouse. We estimate that we have about 9 cords of wood (a cord is 4x4x8 feet) or about 30,000 lbs on hand for indoor fires. The corral has an “entrance” for newly cut wood that needs to age and an “exit” for aged wood ready to burn.

Up to now, we have covered the huge pile with several thick tarps, tied down with bungie cords. However, the past few winters have featured the unwelcome visit of rain, believe it or not, in January and February, followed by cold snaps and heavy snow. This combination has sandwiched thick ice between layers of heavy snow, cementing the tarp to the wood, making retrieval difficult. Next summer, we plan to build a roof over the whole thing, preferably with an extension that can cover a work area during rainy or snowy days.

Our most accessible trees for fuel are spruce, birch, and alder (we don't count willow, which is a poor fuel source). Spruce smells great because it is a resinous wood but it can build up a gunky creosote layer that clogs chimneys the way cholesterol clogs arteries. Many people north of us, in ecosystems with fewer trees, do burn it inside, but we favor it for aromatic, outdoor fires in a rock lined fire pit near our lake shore. It generates 15.5 million BTUs per cord. The second choice, alder, grows everywhere, like an Alaska-size weed, but it burns really hot – so hot, I've read, that “in the olden days” it was used in forges (on the other hand, it generates 17.5 million BTUs per cord – less than some other woods). Whenever I burn it, I see a tornado-like vortex form as the heat rises. So, generally, I soak it for use in my meat smoker, and make some rustic furniture with it, but mostly I burn it outdoors as a trash tree or to help damp or rotted spruce burn better. Our third option, and the one we prefer for burning indoors, is birch. It generates the most BTUs: 23.6 million per cord. When nicely aged and dry, it is light and burns cleanly. The ash in the chimney is easy to clean out (not sticky). Every spring, I dump a winter's weight of ash in my gardens (free source of nitrogen).

In 2011, I wrote a blog article about the danger, process, and time required to cut, limb, buck, and chop up trees for firewood. Here, I'll just say that Bryan uses a gasoline powered chain saw ($300) on the trees and a hand axe ($30) on the logs. A tank of gas lasts for about 2 hours and the process is arduous enough that he needs a break about every two tanks, so it takes several days to cut, move, and store the logs of one tree. Every once in a while, I gather a pile of logs and use a small hatchet ($15) to slice the logs into slim pieces of kindling. My husband is starting to yearn for a log splitter. Electric ones can be had for a few hundred dollars, but we don't find them in Alaska. The gas powered ones are closer to $2000.

In our cabin, we don't have a fireplace. Lovely as they are, even people in more temperate regions know that fireplaces have a terrible tendency to let more heat OUT of a room than INTO it. Instead, we have a wood stove, about $1000. The term may conjure up an image of one of those huge, old fashioned kitchen stoves with multiple oven and stove rings, but this is not what I mean. Ours is a small, squat (maybe 20d x 30w x 
Drolet Eldorado wood stove
25"h), rectangular, HEAVY iron appliance. It is functional, not attractive. Implausibly, it reminds me of a bank safe with a small front window through which one can view the flame. A round, black chimney pipe rises from the middle of the top and exits through the back wall. The stove weighs about 300 pounds and sits on a similarly heavy stone slab ($250) to protect the wood floor. Because it is iron, and because the whole goal is to have the iron walls radiate heat into the room, the appliance is positioned about 18 inches away from the wall, with a portable firewall ($60) protecting the log wall behind it.

The flat top is in constant use. On one side of the chimney always sits a pot of hot water (for humidifying the room and for easy access to warm water to wash ourselves, dishes, laundry, etc). On the other side, depending on the time of day, sits a pot of coffee or stew/soup. Because of these food/washing functions, it is positioned between the door (for easy access to the wood pile) and the kitchen corner.  (I have tried cooking potatoes and other foil wrapped food inside the stove, but they tend to taste burned).

The selection of any wood stove is determined by the size of the cabin you want to heat. Our cabin (750 sq ft) is two simple rooms, one above the other, connected by a spiral staircase. During the night, I always keep the window by our bed cracked a bit, to provide a draw for the heat below. The wood stove is appropriate to heat our two levels, but the temperature can vary by 15 degrees closer/farther from the source (so I store produce and eggs in the coolest corners).  This year, we plan to place under the stove some big rocks that we hauled up from the lake. Will they help heat the room sooner than the stove? Will they stay warm longer?  We'll find out.

In general, we use about 10-12 logs a day to heat our little home (not including kindling etc, too) during the winter months. That's about 70 - 82 pieces per week and about 280 - 330 pieces per month – about 3000 pieces during eight months. Since green wood can be as much as 50% water, and heating for fuel requires boiling that water out before burning the wood, you can see why it is important to have an accessible source of dry (not wet) and dry (not green) firewood handy!

Although the use of wood seems very logical given where we live, there are a number of disadvantages. One, obviously, is the amount of work and space required for wood pile. Another is the lag time between logging and efficient burning. A third is cleaning.  Opening, shutting, filling, and emptying the wood stove (and wood box) generate a lot of ashy dust that coats surfaces in the cabin. Several times during the winter, I feel compelled to run a damp rag over the upper surface of every log in every wall. From our experience, I finally “get” the whole “spring cleaning” concept, and why, in wood heated homes of yesteryear, wealthier families traded out whole sets of winter and summer rugs and draperies. 

For chimney cleaning, there is a trap door access to the exterior length of pipe.  About once a month, on those sunny still afternoons when we decide to let the stove go cold, we open the trap and, with a long handled brush, sweep out about 3 gallons of accumulated soot. At the same time, I clean the surfaces of the stove with vinegar and rags (that get really gross) and then shine it up with a handful of Crisco.  The room smells a bit like baking when we fire it up again that evening.  Just yesterday, we removed the interior chimney pieces for a thorough cleaning that we had clearly neglected for too long.  What a dirty job!  About 2 gallons of shiny, black, flaky soot, like coal, had heated enough to rise partway up the chimney and then accumulating in the horizontal section, starting to impede air flow and causing smoky fires.  So much for combustion!  With a long handled cooking spoon I scraped out as much as I could and then we brought in the chimney brush to scrub it further.     

For these reasons, many people we know with weekend and occasional – use cabins (such as for hunting, fishing, or snow machining) prefer oil fuel stoves. These aren't any prettier, but they expel less detritus into the cabin, the stored fuel takes up less space than wood, and oil is more efficient per pound than wood. However, like wood, it requires some advance planning to (haul and) store enough for a given period of time. Many homesteader cabins in Alaska (and elsewhere, no doubt) fashioned metal roof “tiles” by cutting open and flattening used fuel oil cans which they nailed, in overlapping rectangles, over plywood and tar paper.  

Like other aspects of living remotely, heating requires a certain learning curve, and more time and work than flipping a switch in the city. I've become someone who likes to sleep in a cold room with a warm comforter and to wear several layers of clothing. If you conclude that this is to avoid getting up to stoke the fire or to delay going outside to haul in a load of wood, you may be right.


Energy Comparison
1 pound of wood = 6,401 BTUs = 1.9 KWH
1 pound of coal = 13,000 BTUs = 3.8 KWH
1,000 cubic foot of natural gas = 1,000,021 BTUs = 299 KWH
1 gallon of oil = 138,095 BTUs = 40.5 KWH
1 gallon of propane = 91,500 BTUs 26.8 KWH

Green Economics
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Note: I am pleased to say that I am now a monthly columnist for Alaska Adventure Media publications. The column is titled, “Off the Grid.”


  1. Wow. This post is educational. I hadn't thought about the BTUs of various woods, yet it makes sense. Love the small of burning wood. BTW, I've wondered. How do you and Bryan travel from the cabin to other states?

  2. Very good information!, Alaska industrial Hardware carries Electric wood splitters!

  3. Nice Post! you define very well on the topic of Remote Cabins: Cost of Heating by Wood really nice.Thanks for the post.