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The theory of energy return on investment: a case study of whole tree chipping for biomass in Prince Edward Island

Gingerich, J., Hendrickson, O.
Forestry chronicle 1993 v.69 no.3 pp. 300-306
whole tree chips, energy resources, fuels, biomass, energy expenditure, energy recovery, petroleum, energy use and consumption, fossil fuels, Prince Edward Island
Industrial societies consume vast quantities of fossil fuel resources; the carbon dioxide released when these fuels are combusted is a major concern because of global warming. "Energy Return On Investment" (EROI) is the ratio of energy gain from a resource relative to the energy invested to achieve that gain. EROI analysis shows that the net energy available from fossil fuels decreases as resources are depleted, encouraging a transition to renewable resources which will not be depleted under sustainable management. Renewable resources can reduce net contributions of carbon dioxide to the atmosphere; however, many sources of renewable energy require fossil fuel inputs into their production process. EROI analysis can also be used to determine renewable energy sources with the greatest energy gain, relative to the fossil fuel investment required to achieve that gain. One renewable source of energy with considerable potential for expansion in Canada is wood biomass. A case study of whole tree chipping (WTC) in Prince Edward Island revealed an EROI ratio of wood chip energy gained relative to fuel energy invested of 26.7:1. The major factor affecting the EROI for WTC was transport of the chips to the burning facilities: distance and load size were important components that should be considered when designing new burning facilities. There are some benefits and disadvantages of WTC not captured by EROI analysis that also need to be considered.