Peak Firewood

"Before enlightenment chop wood carry water, after enlightenment, chop wood carry water."

—Shunryu Suzuki-Roshi, Zen Mind, Beginners Mind

We read Nate Hagens recently reposted piece from 2007 on The Oil Drum re: firewood. Hagens ran some interesting calculations. What if everyone got woodstoves? How long before peak forest?

In 2002, the forested area of the United States contained 856,000,000,000 cubic feet of tree volume, of which 364,000,000,000 cf were hardwoods. (This is the forest capital). (Due to larger amounts of creosote and much lower wood fiber density in softwoods, they are not suitable for conventional firewood and I assumed are not used for heating –in a more advanced analysis this assumption could be relaxed as people could harvest softwoods and replant with hardwoods at least to some extent and/or install external wood burners).

The current annual volume growth is 10.1 billion cubic feet annually (or about 2.5%). Existing usage rate is 5.7 billion cubic feet with an annual mortality rate of 2.7 billion cubic feet. (Interestingly, the mortality rate was at a 50 year high and the USFS admit they do not know the reason for it). For ease of calculation let’s be aggressive and assume that humans can access all of the dead wood for burning. We then have 4.4 bcf of annual growth of potential firewood that is not otherwise being utilized for lumber, electricity or current home heating. At 128 cubic feet per cord, this equates to approximately 34.7 million (more) cords of wood that can be accessed sustainably, without dipping into the forest ‘capital’. If we discontinue other current market uses for the wood we would have 10.1 billion cf or 78.9 million cords of potential firewood per year.

Freshly cut wood has over 60% moisture and therefore takes much more effort to release the energy in the wood fibers. Seasoned wood approaches 20% moisture content and releases about 6,400 BTUs per pound of wood. (Pure bone-dry wood tops 8,000 BTUs per pound but is not practical for home use). Almost all wood types create the same amount of BTUs per pound (6,400), but depending on their individual densities and other properties, differ in how many pounds make up 1 cord.

This analysis assumes one cord of wood typically is about 2400 pounds. We then arrive at 2,400 X 6,400 BTUs =15,360,000 BTUs per cord. Therefore, in the 52 US states, we have 34.7 million cords of annual volume growth of wood available times 15.36 million BTUs per cord => 533 Trillion BTUs that can be presently be accessed sustainably from hardwoods. (If we eschew all other forest products, this number roughly doubles, and if we include softwoods, it roughly doubles again)

[This compares to 7000 Trillion BTUs contributed by natural gas for home heating at present. - ab]

So the good news is if we were really cold and sans fossil fuels, we could chop down trees for at least 4 years before the US would resemble Easter Island (24,024/5,074= 4.74 years). [If we could keep out poachers, TN could go about 10 yr -- ab]

Last week we had a brief warm spell, and we were back working on the wood pile, with plenty to meditate on. Good thing we did. The fresh snow this morning makes it hard to find the chopping block (see our Facebook wall for more photos). One of the Oil Drum commenters, Don in Maine, remembered (and here we reverse his paragraph order):

Scott Nearing, when he went to friends to have dinner always wanted a spell at the wood pile first, than some home grown food and dandelion wine, and talk of economics into the wee hours.

In a society that answers every problem with a pill, splitting wood is zen. Your anger, your frustration, your doubts are gone. The body kicks in and the mind gets the rest it needs. I never come in from the wood yard in a bad mood, I look back outside and what I see is that I have been highly productive. So many of the ills some people face actually seem much less of a problem with some fresh air and work. Depression is a big one, anxiety another, hard to be either when you made a big pile of split wood, raised a good sweat, and are tired.

Mostly you end up hungry.

We would also add that arm exercise is much more exhausting than leg exercise. More adrenalin is released, your heart beats more rapidly and beats harder. But, after that cardio-flush, you have elevated levels of the brain chemicals that lower anxiety.

Exercise sends norepinephrine to brain regions involved in the body's stress response, according to work being done at the Univ. of Georgia. Norepinephrine is particularly interesting to researchers because 50 percent of the brain's supply is produced in the locus coeruleus, a brain area that connects most of the other regions involved in emotional and stress responses. The chemical is also thought to play a major role in modulating the action of other, more prevalent, neurotransmitters.

It isn’t entirely neurochemical, however. Biologically, exercise seems to give the body a chance to practice dealing with stress. It forces the body's physiological systems — all of which are involved in the stress response — to communicate much more closely than usual: The cardiovascular system communicates with the renal system, which communicates with the muscular system, and so on.

So, before enlightenment chop wood carry water, after enlightenment, chop wood carry water. Another Japanese saying is “He who chops wood is twice warm.” Except, it now appears, not all of us can stay warm in the winter that way any longer.