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[GreenYes] RE: [ZWIA] Re: LA Zero Waste pans

Apologies for cross-posts... it's hard to know who's on which list above.

Jeff, have you run MBT through your calculator? Here in Metro Vancouver we are being told that WTE is the best solution for "residuals" that have been subject to 70% diversion through composting (food, yard, contaminated paper) and recycling. Can we make a case that investment in MBT for the remaining 30% is a better idea than investment in WTE?


At 10:24 AM 1/29/2008, Jeffrey Morris wrote:
Hey Everyone,
Many of you have obtained the model/calculator for the environmental benefits of recycling and composting from me.  Because of the great dialogue on composting versus incineration on these list serves, I thought I should mention again that the model does include in the environmental benefits of composting the upstream pollution prevention from reduction in the use of synthetic fertilizers and pesticides, and the carbon sequestration benefits of compost applications and the resultant healthier soils and plants. 
The version I sent around assumes that compost use offsets 50% of the average level of synthetic fertilizer and pesticide use on home lawns and gardens.  The model can calculate any level of offset between 0% and 100%.  The model also takes into account the build up of carbon in the soil from the use of compost, both as a result of the addition of carbon in the compost itself and as a result of the increased humus formation as a result of better plant growth. 
I picked the 50% fertilizer and pesticides offset estimate based on the observation that someone who buys compost for their lawn or garden is not likely to continue to buy the same amount of synthetic fertilizers and feed/weed type of products.  One might argue that the offset should be higher.  My usual tactic in the calculation of environmental benefits is to make assumptions that are if anything biased toward the burn or bury proponents.  The results still come out favoring recycling and composting, and it?s then hard to make the case that my analysis is biased toward recycling and composting.  However, one could run the model at 100% offset of synthetic fertilizers to see how much additional benefits accrue from going totally green!
The offset assumption for pesticides is also 50% in the baseline model.  Some of this is from the reduction in purchases of synthetic fertilizers that include herbicides (weed ?n feed products).  Some is from the reduced need for herbicides and pesticides due to the stronger plants that result from a natural lawn and garden care approach. 
The carbon build up estimate is from EPA/s WARM model and the supporting document Solid Waste Management and Greenhouse Gases: A Life Cycle Assessment of Emissions and Sinks (3rd edition, Sept 2006).  The synthetic fertilizer and pesticide offsets are based on a study that an economist at Seattle Public Utilities, Jenny Bagby, and I did on backyard composting and natural lawn and garden care.  That study has been peer reviewed and accepted for publication in the International Journal of Life Cycle Analysis.  The article is published online awaiting its turn in the queue for publication in the printed journal.  The abstract can be found at
One other point ? the model includes other environmental benefits in addition to climate change benefits from recycling and composting.  It?s important to remember that human toxics and carcinogens, ecosystem toxics, acid rain, smog, ozone depletion, habitat alteration, species biodiversity, and water nitrification impacts are also reduced by recycling and composting.  In total these other impacts are of at least equal if not greater importance than climate change.  
Many thanks and much appreciation to those of you that are out there everyday promoting clean and green behaviors.  At some point we?re bound to reach a tipping point away from our chemically drowned lifestyles.
Best wishes,

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