Wednesday, January 30, 2019

Seven Fat Cows 2.5: Firewood planning

Back in Michigan, Rick picked up the event on his news feed. He kept one specifically for winnowing through the blizzard of the 24-7 news items looking for key terms like “Emergency Room”. His feed picked up the unfolding events in Minnesota but Rick accepted the explanation that a sewer pipe had broken.

Meanwhile, Rick continued to worry about the availability of firewood.

Rick sincerely believed that energy is the keystone resource. Food is one kind of energy. Firewood is another.
A heat map of the population density and the wood resources.

A rough estimate of the new, larger neighborhood was that it held 150 homes. Most were clustered close to the paved roads, that is, they were biased to the east and in the northwest corner.

The woods were scattered but most of them were oriented through the middle on a north-south axis with heavy concentrations on the southern border.

About half of the 400 acres of woods were on parcels where the owner lived. The other 200 acres were on the property of absentee land-owners or belonged to commercial farmers.

Looking at the parcels with few standing trees, those 100 or so homes had 200 acres of woods or about 2 acres per home, assuming the farmers were willing to let residents harvest those woods.

Rick and Kelly had done a little bit of ‘tresspassin’ hunting rabbits in late winter. Afterward, Rick estimated that most of those woods had 100 trees per acre and about 12-to-15 full cords of standing wood per acre. Some was better. Much was worse. After all, it was marginal ground that had been allowed to revert to woods.

Assuming the neighborhood could create a logging industry from nothing, that 2 acres per home would supply enough heat for three years at current rates of consumption.

Rick was on good terms with the farmers. He was pretty sure that they would be more than willing to let neighbors pay them to clean out fence rows and pot-holes in the middle of their crop fields.

The key point was neighbors would need something to use as currency, something the farmers wanted. Rick figured that they would be willing to let some of the neighbors to cut on shares. After all, the two commercial farmers in the neighborhood heated with wood and there would not be much of a market for their corn, beans and wheat if the money economy collapsed.

Rick deduced that he needed a two-pronged approach. He needed to lower expectations to reduce the demand and he needed to boost production.

The standard rule-of-thumb is that a northern woodlot produced between a half to one full cord of wood per year. To make the math in his head easier* and to wash out the difference in the heat content of various types of wood, he rounded that to the energy in fifty-to-one-hundred gallons of heating oil and a typical home might burn a thousand gallons of heating oil a winter.

That was the basis for “needing” fifteen acres of woods to heat a home.

Like all broad generalizations, there were some significant caveats. Younger woodlots of selected "biomass" clones that were treated like row crops and  produced significantly more wood per year. In some cases, as much many BTUs as two or three hundred gallons of heating oil per acre, per year.

Other advantage of these super trees is that they would be large enough for small stove-wood in three years and big stove-wood in eight, they grow well on muck and they can be planted by simply sticking 8” of a 10” cutting into the ground.

Rick decided it was a good time to start a small nursery where he could harvest cuttings in the future. He ended up purchasing a hundred cuttings of two kinds of hybrid poplar (NM-6 and DN-177) and three kinds of hybrid willows (Millbrook*, Fabius* and Preble*). He also bought a couple pounds of Black Locust seeds and thought he would try his hand at growing some of them.

Some of the varieties were patented and propagation was prohibited. If the rule of law went into the septic tank, that would be the last of Rick's concerns.

If events did not go pear-shaped he could plant the Black Locust around the edges of his ten acres of swamp and the poplar and willow in progressively wetter parts of it. If they did go pear-shaped he could supply cuttings and seedlings to convert excess crop ground into short rotation firewood production.

*Twenty-five pounds of air dried wood has approximately the same amount of heat energy as a gallon of heating oil.

Next Installment


  1. I actually graphed the available heat from wood versus moisture content and curing time back in 2005.

    It was during winter, so I guess I had that excuse.

    1. That is a great idea!

      Curing times will be highly site dependent but moisture content vs heat available might be useful information.

      Somebody ought to write a blog post....

  2. I just noticed that the population density heat map would look a lot like the US population density/resource base if you spun it around the horizontal axis.

    Purely unintentional. Interesting but unintentional.

  3. Are you sure about the comparison of wood to oil?

    Doesn't seem right.

    1. "All firewood has about the same BTU per pound. Non resinous wood has around 8000 to 8500 BTU per pound and resinous wood has around 8600 to 9700 BTU per pound." (

      Number 2 heating oil has about 136,000 BTU per gallon.

      The heat of vaporization for water is 970 BTU per pound.

      A cord of air-dry gofer wood is 2200 pounds and a cord of soft-maple/elm mix is about 3000 pounds.

    2. Petroleum-based fuels such as #2 weigh about 8# per gallon. According to the quote, it produces double the BTU of wood.

      This does not take into account the locating of oil, refining it, pumping it, transporting it. Based on the complete picture, oil is handy... but a 'net loss'.

      How many BTU to cut wood aka calories burned by the sawyer?

      Instead of competing with weather through brute-force (burning the forest legacy), below-ground or earth-sheltered dwellings make sense to me.

    3. Hello Miss Larger-than-life:

      Lots of things make sense and there is no guarantee people will do them.

      If energy for space heating becomes dear then it makes all kinds of sense to shrink the building footprint that is heated. In 1950 Americans thought we were rich when the average home had 300 square feet per occupant. In 2000 it had ballooned up to 840 square feet per person.

      It requires less investment, at least in the short term, to close off rooms or to pack multiple families into an existing house than to rebuild underground.

      Of course, it also makes sense to not burn green wood.

      Thanks for writing.

  4. So closer to 14-16 pound equivalent best case, not counting water.. I will buy that.

    Sorry, It just didn't seem right.

    1. I put in ample Kentucky windage to account for the fact that most people store their firewood where mist and rain can get to it. Also, the actual R/H is the average of the daytime and nighttime R/H which is lower than daytime alone.

      Thanks for asking. It keeps me honest....Joe

  5. Nice! And prepping does work. Just not as fast as he wants it to.

  6. When I pick up an armload of dry wood I think, that is probably a gallon of propane! The sun and wind, plus wood that dries well makes wood heat feasible. Running your stove right is important. We tend to run a hot, small fire until it gets really cold, when we will fill the fireboxes. When we run the stoves right, the flues need only an occasional cleaning. Warm weather is coming this weekend and I will go up on the roof to scratch out the flues and give myself a grade on how I have been running the fires.