Fast pyrolysis and Wood Chips

I attached a link here to a critical review paper on the pyrolysis of wood and other biomass that was published last year in Energy and Fuels(2006, 20, 848 - 889). As I have recently posted, our two options for the production of transportation fuel that can use our current engine technology without a massive overhaul is algae derived biodiesel and wood chip derived oils using heat and or pressure.

Algae, though largely undeveloped offers the promise of a very labor efficient oil and cattle fodder production system operated even on otherwise non agricultural lands. It really lends itself to automatic pumping systems, filter presses and the like with potentially very high yields.

Wood chip processing will produce oil and char through the process of heating. The article gives us an approximate 25% yield for a slow pyrolysis with a 24% char yield as well. Fast pyrolysis promises to give us nearly 75% yield with a 13% char content. Obviously, fast pyrolysis needs to be perfected. Without question pyrolysis will produce a liquid component that I am loathe to call oil as yet but can obviously be processed into a working fuel.

The difficulty of course, is that wood chip production is never going to be particularly labor efficient. We have discussed the need to properly manage woodlands throughout this blog. If woodlands can now produce an economically viable crop in the form of wood chips, we go a long way toward the restoration of the productivity of these woodlands.

The optimal annual yield of an acre of temperate woodland will still be around one ton per year per acre of woodland. The value to the owner operator of this ton of wood chips will need to cover its cost of recovery and removal. With fast pyrolysis we are suddenly looking at around five barrels of oil equivalent production per year per acre. This may actually be financially viable for the owner a participate in with oil in the $100 plus range.

Other occasional agricultural bio waste can also be fed into the system, although the direct value of most of these feed stocks as local bio char will surely dominate.

Again, we face a very significant haulage cost component. A 1000 ton per day processor needs to draw from 365,000 acres of woodland. This quickly looks like 500 net square miles or in country with a minimal woodland component, a draw radius of thirty miles at least. That is a lot of haulage.

And that 1000 ton per day facility will produce perhaps 5000 barrels of oil equivalent and some charcoal. By oil industry standards this is significant but still fairly modest.

The principal benefit of a wood chip conversion system is that it can be easily tweaked to drive good woodland management practices, which has been sorely missing to date. It may even end up been completely self sustaining.

The benefit for the owner operator is that his woodlot is economically self sustaining while he is growing a profit in the form of sawn wood and any fruit production.

The technology will also be easily implemented in the tropics were the wood waste content per acre is several times what can be achieved in the temperate zone. Of course, moisture content will be difficult to manage.

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