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  • From: "robscott@freeshell.org" <robscott@freeshell.org>
  • To: permaculture@lists.ibiblio.org
  • Subject: Re: [permaculture] Miscanthus
  • Date: Fri, 9 Sep 2005 15:42:56 +0000 (UTC)


Greetings Earthlings.

In response to Martin Taylor's "wouldn't hemp be a greater resource?" and Larry London's "what about amaranth/pigweed?", I'd like to share the following. The University of Illinois in Urbana is currently investigating Miscanthus as a substitute for coal in the power plant.
Here are some of the specs:

Miscanthus is a perennial grass propagated by rhizomes.

The variety being used in Illinois is difficult to establish, needs a wet area and doesn't seem to produce fertile seeds. Establishment takes 2-3 years.

From then on, this miscanthus grows 15' tall each year in Illinois.

The material which is harvested is the stalks of the inflorescence. It is harvested in winter after the roots have resorbed N, P, K, S, etc.
Most leaves have dropped at that point leaving a duff on the soil.

What remains in the stalk is mainly Carbon, with traces of Silicon and Aluminum. The Stalks are burnt at >1800F, and the ash "slays" glass as the main mineral output. This Silicon could be put to good use for developing a head shop to service the by-products of a complimentary hemp industry.

The University of Illinois land is naturally (1) wet, and (2) a tallgrass prairie. So the use of a tall grassland to produce fuel is a fairly close approximation of the natural biome. There are no records of miscanthus invading pristine ecosystems in Illinois (maybe because we don't have many pristine ecosystems). The winter harvest allows for wildlife populations to establish and make use of the habitat for the full growing season, including grassland birds.

Reports suggest that 1 acre of Miscanthus generates enough heat to fuel 3 middle-class U.S. houses -- or, lets say, a dozen energy-efficient Permaculture houses. The acre of Miscanthus is a monoculture in this measurement. Permaculture designs could experiment with new systems.

Other crops being investigated are switchgrass (Panicum virgatum) and Cattail (Typha spp.). Again it is the dry remainder of the last season's growth which is harvested - sometimes called the "carbon skelatons". Plant nutrients which are scarce overwinter in the root structures dedicated to storing photosynthate (that's the point with perennials). The idea is that you use the non-scarce elements to combust for energy, assuming there will be no shortage of C, Si, or Al for future plant growth. Plants get C from atmospheric CO2, and clays are aluminosilicates. Si makes up about 27.5% of the earth's crust and Al is about 8% - that's why you don't read about C, Si, or Al shortages effecting farms or ecosystems.

So that's the case for miscanthus. Using "carbon skelatons" instead of carbon fossils. A comparison to pigweed would require some idea of the chemical composition of dead stalks, biomass per acre, and BTUs or kWhs per unit of biomass at agiven temperature. The data on miscanthus are still being collected.

Rob Scott
Urbana Permaculture Project
Urbana, IL




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