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GSBN:A question about quantification of carbon sequestration in a bale and bale structures






Kelly must be out of touch right now, so I'll toss in this little calculation she did some years ago related to her work in China. Note that it also confirms and underscores Derek's point: that there is nearly zero effective sequestration in the bales themselves. The real benefit is in the insulation and thus fuel savings related to heating and cooling.

Message copied below. John Straube, I believe you said you did some calculations around this issue, or are you off and away someplace and ignoring us?

Bruce King

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Kelly Lerner wrote in 2000:

While carbon sequestering is a clear benefit of straw-bale construction, it pales in comparison to the potential benefits of reduced carbon dioxide emissions (due to energy efficiency) over the life of the building. Of course, these benefits only accrue in a climate which requires heating or cooling. Just some quick math and simplistic explanations (all that will fit in an email) which reflect our projects in China:

We're building new straw-bale houses which would have been new brick houses. In Heilongjiang, the new brick houses burn 5 tonnes of coal/winter. Let's say our straw-bale insulated, day-lit, passive solar model will be 75% more efficient - only use 1.25 tonnes of coal/winter - basically, families are now heating with just the fuel they need for cooking. [EditorÕs note: this assumption was later born out by a survey of coal usage in the area.] That's a savings of 3.75 tonnes of coal/winter. My carbon reduction consultant tells me each tonne of coal gives off 1.3 tonnes of CO2. Let's say (as the politicos dictate) that the effective lifetime of the house is 30 years (even though we know it will last much longer). The total please: 3.75 tonnes of coal/winter x 1.3 tonnes of CO2/tonne of coal x 30 years = 146 tonnes of reduced CO2 emissions over 30 years. Of course this equation doesn't take into consideration improved air quality, higher comfort, improved health, reduced clay mining and brick manufacture, increased seismic safety, etc. etc.

CO2 Reductions
* sequestration 3 tonnes +/-
    * replacing bricks with straw (reduce brick firing)       3 tonnes
* reduced brick transportation 1 tonne * reduced emissions 146 tonnes

			Total 						153 tonnes reduction per house