Project 2 – Consequential Life Cycle Assessment of Using Wood Pellets in Greenhouse Production to Replace Conventional Fuel Types

Location: McGill University
Research team: Paul J. Thomassin, Kakali Mukhopadhyay, and Réne Roy
Duration: April 1, 2012 – March 31, 2013


A Life Cycle Assessment identifies all of the energy and material flows within the life cycle of a product, material or service as a means of evaluating the environmental impact of that product, material or service (ISO, 2006).   There are two generally recognized types of life cycle assessments (LCA); the attributional LCA and the consequential LCA.  The differences between these two types of LCAs are how the systems are delimited and the type of data used in the analysis (Reinhard and Zah, 2011).

Attributional LCA is the traditional approach to the analysis and concentrates on identifying the physical flows within the system from cradle to grave.  The system is limited to the life cycle of that product, material or service.  Average data is used in the assessment so that the average environmental impact per unit of production can be estimated (Ekall and Weidman, 2004).

Consequential LCA broadens the system under analysis to include the environmental flows of other relevant systems that result from the decision (Reinhard and Zah, 2011).  This approach uses economic data to measure the physical flows of indirect affected processes (Earles and Halog, 2011).  Consequential LCA is a relative new approach for environmental analysis and no consensus has been reached on how the approach should be undertaken (Dandres et al, 2011).

A consequential LCA will be undertaken to analyze the environmental impact of using wood pellets as a renewable fuel source in greenhouse production to replace traditional heating fuels.  Greenhouse production has increased in Canada from 17.8 million square meters in 2001 to 22.7 million meters in 2010 and has sales of over $2.3 billion (Chaudhary, 2011).  One of the major input costs in greenhouse production is heating.  Traditional heating sources include natural gas, oil, electricity and propane.  Sudden changes in the cost of heating fuel have created concern for the economic viability of greenhouse production (Chaudhary, 2011).  An alternative heating source is wood pellets.   Canada produces over 1.45 million tons of wood pellets of which most are exported to Europe.

A consequential LCA will be undertaken for wood pellets as a fuel source for greenhouse production.  The approach to be taken will be to incorporate into the Canadian Input-Output model a greenhouse production sector that includes alternative fuel sources.  This will include modelling the wood pellet industry.  A price version of the input-output model will be used to evaluate marginal changes in prices as the demand for wood pellets changes.  The consequential LCA will include both the economic and environmental impacts of changing the fuel source in greenhouse production.  The environmental impact will include energy and a number of gases; ex. CO2, CO, SO2and NOx.


The project is innovative in that it will apply a new technique for undertaking a consequential LCA using Canadian agriculture as an example.  The input-output model will be modified to take into account a greenhouse production sector that includes alternative energy sources, a wood pellet sector and a series of environmental indicators to provide an estimate of the environmental impact of the alternative fuel choice.  The input-output price model will also be used to estimate changes in prices and the demand for alternative fuel sources.  Finally, supply constraints on the production of wood pellets will be introduced in the model.

The energy and emission data for wood pellets as a fuel source in greenhouse production will be generated from a current study on this technology at McGill University and other secondary sources.  Currently, two greenhouses have been fitted with wood pellet burners and emissions and energy estimates are being undertaken by a professor in biosystems engineering at McGill University.  An agreement to share the information is in place.


A final report summarizing the results of the research project will be delivered at the completion of the overall project. Training is provided for one PhD student.


Chaudhary, G. Nabi. 2011. The Economics of Production and Marketing of Greenhouse Crops in Alberta. Alberta Agriculture and Rural Development. Agdex821-59.

Dandres, Thomas, Caroling Gaudreault, Pablo Tirado-Seco, and Rejean Samson. 2011. Assessing Non-Marginal Variations with Consequential LCA: Applications to European Energy Sector. Renewable and Sustainable Energy Reviews 15:3121-3132.

Eales, J. mason and Anthony Halog. 2011. Consequential Life Cycle Assessment; A Review. International Journal of Life Cycle Assessment 16:445-453.

Ekvall, T. and B.P. Weidema. 2004. System Boundaries and Input Data in Consequential Life Cycle Inventory Analysis. International Journal of Life Cycle Assessment 9(3): 161-171.

ISO 14040 International Standard. 2006. Environmental Management –Life Cycle Assessment- Principles and Framework, International Organization for Standardization. Geneva, Switzerland.

Reinhard, Jurgen and Rainer Zah. 2011. Consequential Life Cycle Assessment of the Environmental Impacts of an Increase in Rapemethylester (RME) Production in Switzerland.  Biomass and Bioenergy 35:2361-2373.