Calculations for CO₂ Offsetting by Stoves

A 2007 study commissioned by Climate Care Ltd. quantified the amount of firewood required to cook family meals in Honduran homes with traditional stoves vs. TWP's improved cook stoves. Continued measurements of reductions in firewood consumption among several types of Justa Stove and other Ecostove users showed that the average estimated reduction in emissions during normal household use is 1.5 tons of carbon dioxide (CO₂) per year, per stove.

Multiplying 1.5 tons of CO₂ per year per stove by 5 years, the expected lifespan of one properly maintained TWP stove, yields a conservative total of 7.5 tons of CO₂ that will be prevented from entering the atmosphere when a family transitions to one of TWP’s Ecostoves.

Reference
Climate Care Ltd., Ambiental PV, ENASA. 2007. "Kitchen Performance Testing, Tegucigalpa, Honduras and Managua, Nicaragua 2007."

Calculations for CO₂ Offsetting by Trees

We used data provided by the Ministry of Agriculture of El Salvador and Hidayat & Simpson (1994) to determine the specific gravity of wood from the six tree species TWP plants to offset CO₂: Spanish cedar, mahogany, rosewood, mango, cashew, and Maya Nut. The average of the six species was 639 kg/cubic meter of wood. Our Guatemala Project Director estimated that these species have an average of 3.5 cubic meters of wood at maturity. Multiplying average specific gravity by average volume yields an average biomass of 2,237 kg per mature tree. Tree biomass is approximately 50% carbon, resulting in 1,118 kg or 1.118 tons of carbon per mature tree. Therefore approximately 0.9 mature trees offset 1 ton of carbon. Because trees may die before reaching maturity and because of potential sources of error in these calculations, we plant 5 tree seedlings to offset 1 ton of carbon.

Reference
Hidayat, Syarif and William T. Simpson. 1994. "Use of Green Moisture Content and Basic Specific Gravity to Group Tropical Woods for Kiln Drying." Research Note FPL-RN-0263. Madison, WI: USDA Forest Service Forest Products Lab.

Calculations for CO₂ Offsetting by Solar Heaters

Your carbon offset purchase goes into a dedicated fund at Trees, Water & People to build “carbon offset heaters.” Once we have sold 28 tons of carbon offsets (the total lifetime of avoided emissions for one heater), that means we have enough money to build a solar air heater collector panel. We combine these carbon offsets funds, which supply the collector panel, with existing funds to pay for the remainder of the heater kit and its installation. That means that, thanks to you, our “carbon offset heaters” will be up and running, preventing the use of carbon-based fuels, and heating homes of families in need. We would not be able to build these heaters without your contribution!

Our “carbon offset heaters” only go to homes that would otherwise get heat from electricity or fire wood, both very common heat-sources on Native American reservations, where we distribute almost all of our systems. The average carbon dioxide emissions avoided by using solar air heaters instead of wood or electricity is 3,072 pounds annually according to the Rural Renewable Energy Alliance (http://www.rreal.org/solar-assistance/pricing/). At 2,204 pounds per metric ton, that means our heaters avoid 1.39 metric tons of carbon dioxide each year. Barring any damage, our collector panels have a 20 year lifespan, leading to a total of 27.8 metric tons of carbon dioxide avoided in a panel’s lifetime.

Calculations for CO₂ Emission Levels

We obtained the figure of 20 tons of CO₂ emitted by the average North American by averaging the six references listed below. We used the four carbon calculators listed below to enter hypothetical parameters to come up with an estimate of CO₂ emitted by each of the four lifestyle descriptions.

References
Coombes, Andrea. 2007. Turn Down the Heat. MarketWatch from DowJones.

Raich, Jim, Ricardo Bedoya, Eugenio Gonzalez, & Ann Russell. Biomass Production and Carbon Sequestration by Tropical Tree Species in Experimental Plantations in Humid Lowland Costa Rica. PowerPoint presentation. 

Union of Concerned Scientists. 2006. What’s Your Carbon Footprint? Greentips Environmental Ideas in Action.

CO2 Emissions by Country. Time for Change.

The World Bank. 2007. The Little Green Data Book 2007. Washington, D.C.: The World Bank. 

O’Neill, Meaghan & treehugger.com. 2006. Welcome to the Slate Green Challenge. Slate Magazine.

Carbon Calculators

www.carbonfund.org/site/pages/individual/category/
Carbon%20Calculators/

www.carbonify.com/carbon-calculator.htm

www.nature.org/initiatives/climatechange/calculator/

www.terrapass.com

* all tonnage figures are in metric tons. One metric ton = 2,200 lbs