Tuesday, March 20, 2007

Is converting organic waste to fuel oil the best option?

Tropical soils are almost invariably low in organic matter. Add warmth, water and energy from sunlight and microbiological processes that break down organic matter work just that much faster. So in the tropics, organic matter in soil tends to reduce quite quickly.

The strange "terra petra" soil of the Amazonian - black soils in an otherwise red landscape - now are believed to have been created by adding high levels of carbon, possibly from burnt organic matter AND they are fertile.

Australian soils in general need added carbon.........with organic residues seen as the prime source of this material, along with practices such as green manuring, cover crops and related practices. It works, with a good story in a post a few days back.

Turning organic matter into energy often deprives soils of the materials they need most. Some biomass to energy processes are inefficient, yet using pyrolysis [ see
www.dynamotive.com] may be an option which leaves the important residual carbon still available for use in rural soils. This is a different situation in comparison to burning or gasification of the biomass, which uses a lot of the carbon. This is a common practice for energy production in Europe, but often the system produces low heat values suitable for district heating with hot water, and gets rid of a lot of waste volumes, with smaller residues going into landfills.

A recent Productivity Commission report on waste management has clearly shown that highest economic efficiencies occur with using landfills, and they argue, we still have plenty of space. So why look for any alternative, even composting? Or at least that was their argument, in 2006.

With the pyrolysis system, the carbon remains as char, which is, in effect, concentrated carbon that is cheaper to move in transport and on farm distribution systems. Logistics has been a crucial issue in getting compost, mulch and related products moved from generation areas in Australia - commonly large urban agglomerations - back to high volume users in rural areas.

Adelaide has some advantages, with relatively close high value vineyards that can be a sink for aerobically converted or composted organic products. And they are relatively commonly used. But many other urban areas are not so lucky to have agriculture and horticulture so close, so highly concentrated carbon sources may have some advantages.

It is true that other microbiological processes that convert organic residues into soil incorporated organic matter have other important attributes such as disease suppression, weed and nematode reduction. There may be a place for both types of products.

Added soil carbon appears to have a lot of scientific credibility in enhancing soil productivity. Australia needs to develop improved means of getting it where it is needed. Sure, conservation tillage has helped with improved soil carbon balances in many areas, but there are many areas where adding soil carbon is still a critical issue. Better soil carbon balances also enhance soil moisture capacity, a very critical issue improving plant and crop performance

Is there then a place for both converting organic matter to fuel oil with an added benefit of carbon as char, as well as direct composting of the materials? Or is it just another hot air story like so many other "talk is cheap" biomass to energy conversion scams that have been a feature as money disappearing black holes in the last 10 years in Australia and elsewhere? Some have cost investors a LOT of $$ with nothing to show..........and in some cases the $$ seem to have disappeared overseas.

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