Alder Burns wrote:Lots of people have thought about this dilemma for a long time. Generally, the faster a tree grows, the lighter and less dense the wood will be, and, thus, the heat output will be less. Very hard dense woods will produce the most heat, but they also tend to grow slowly.
Mike Cantrell wrote:Well, I'm doing a little more homework.
Industry is leaning toward willow and poplar:
In California, they can grow 20 dry tons per acre per year with Eucalyptus:
Long and boring (tl;dr = black locust and maple are good), but full of excellent info, " Biomass yield and cost analysis (4th year) of various tree species grown under a short rotation management scheme in eastern Kansas":
University of Illinois likes Black Locust too (Year 3, 12Mg/ha or 26.9 tons/acre (1 megagram/hectare =2.24 tons/acre), that seems implausible, wow):
From Energy Plant Species: Their Use and Impact on Environment and Development by Nasir El Bassam (mostly viewable on Google Books):
"In comparison to other wood species, black locust produces the highest biomass yield as a result of its early growth and high density. In field experiments in Austria, annual dry matter production between 5 and 10 t/ha was reached by three and four year rotations of black locust stand from 10,000 trees/ha (Muller, 1990). The four year rotation reached an increase of yearly dry matter yield that was some 1.4 times higher than that for the three year rotation. The moisture content of the wood ranged between 30% and 38%."
"Experiments have shown that the heating value of the bark is higher than that of the wood: Strigner and Carpenter (1986) reported average heating values of 20.81MJ/kg for bark compared with 19.4MJ/kg for wood."
Luke Townsley wrote:If it were me, and I were just interested in firewood, I would see what is trying to grow there now and seriously consider just letting it grow thinning and coppicing from time to time. You will likely be able to get a large part of your firewood from other parts of your land and from helping friends from time to time. However, firewood takes so long to grow and is such a low value product, I would be thinking about ways to stack functions.
Michael Cox wrote:Mike - I think these figures are deceptive as they are based on chipping for massive scale furnaces, replacing coal and the like. Other factor become considerable more important when hand processing on small scales.
Michael Cox wrote: Big steps to needing less fuel come from insulating a draft proofing the house properly, as well as using an efficient stove.
Michael Cox wrote: My view would be to plant with a mix of species that also produce secondary crops - fruit, nuts etc...
Nitrogen fixers can be coppiced and standard apples left to grow slowly yielding fruit, increased fertility and fuel wood from the same space.
Regarding wood - denser woods generally are better - you needed to handle far less of it to keep the fire going. We burn chestnut coppice and some occasional oak. When we are burning oak we load the fire far less frequently.
R Scott wrote:Locust is a legume and common support tree for food forest establishment. Most will get cut down in 5-10 years, so that is your woodlot for a few years.
'BLACK LOCUST', 'FALSE ACACIA'. Fragrant white pea-like flowers in dense clusters to 4 - 8" long
in May and June. Open-crowned tree to 80 feet, with graceful pinnate leaves. E. and Central U.S.
Zone 3. A valuable and useful tree, producing hard, durable wood, and an excellent fuelwood crop.
Produces up to 100 cubic meters per hectare at 10 - 20 years old, and can be coppiced.
Good erosion control and soil builder, fixing 600 lbs N/acre in 20 year old stands.
Good wildlife browse and bee forage, producing an exceptionally fine honey.
The leaves crushed in water have been used to kill flies. The seeds are said to have been
boiled for food by the Indians, but are toxic raw. One of our finest native trees.
Yet another native species being falsely labeled an alien invader and being killed in the eastern US.
Jerry Ward wrote:Think about Osage Orange. From what I've read the BTU level is crazy high, approaching the level of coal. They could also form part of a living fence around your place and it is supposed to coppice well.
You might also want to check out http://permaculturetokyo.blogspot.com/2006/05/top-10-fuel-trees-for-zone-5-and-above.html
Steve Hoskins wrote:It's our 5th year burning black locust and while it is hard on the saw, it is great firewood. Anytime I burn something else I am reminded just how great.
It coppices very well, and will grow on sandy Michigan soils with no attention.
Mike Cantrell wrote:
I have a buddy who's skeptical of my plan because of the thorns. How do you cope with them?
S Bengi wrote:All plants have about the same conversation ratio for sunlight and so produce the same amount of btu per acre under optimum conditions.
Given that nature is not always under optimum conditions plants that fix there own nitrogen are normally the best such as adler (wet to regular), honey locus (dry to regular), etc
Tim Whittaker wrote:Link with BTU/cord
Hybrid Poplar is something I'd been wanting test out
It doesn't have a very good BTU/cord, however BTU/acre is a different story
"We recommend planting 1200 trees per acre, which means spacing your trees on 6'x 6' centers. These 10” unrooted Frysville Hybrid Poplar cuttings when planted as early as possible in March thru May will reach heights of five to eight feet by the end of their first summer. By the end of the second growing season they will have reached heights of from 10 to 14 feet and by the end of four years will be approximately 25 to 30 feet high. We suggest the planting of ¼ to ½ acre per year according to your needs with unrooted cuttings. This will be done for four successive years. At the end of four years the trees from the first years planting of ¼ acre will have reached 25 to 30 foot high, should be approximately 4 to 6 inches in caliber and should yield 3 cords of great firewood. On the second and succeeding harvest this same planting will yield five cords. This size is just right without having to split it to fit into your stove."
9-12 cords/acre =160-200MBTU/acre
Seems like there is already a permies thread