UBC Theses and Dissertations
Development of British Columbia wood pellet life cycle inventory and its utilization in the evaluation of domestic pellet applications Pa, Ann An
An in-house life cycle inventory (LCI) database for British Columbia (BC) wood pellets is established. The LCI database is used to compare the performance of BC pellets exported to Rotterdam and BC pellets staying within BC in terms of energy penalty, percent of fossil fuel content in pellets arriving destination, and impacts (human health, ecosystem quality and climate change) by performing life cycle impact assessment (LCIA) in a commercial LCA software. The database is also utilized to assess two domestic applications of BC wood pellets: replacing natural gas combustion in UBC district heating facility with wood waste or wood pellet gasification, and replacing firewood in BC residential heating with wood pellets. Overall, the analysis indicated that marine transportation is responsible for over 40% of the life cycle energy consumption and more than 50% of each of the impact categories investigated. The energy penalty and fossil fuel content of exported pellets are roughly 50% and 90% higher than that of the non-exported pellets. For the district heating case study, the base scenario performs much better than all biomass gasification systems in all impact categories other than climate change. The saving in GHG emission is approximately 81% if woody biomasses are utilized. Over the entire life cycle, controlled wood waste gasification system performs better than controlled wood pellet gasification system due to the extra processing required for wood pellets. However, when looking at the health impact associated with stack emissions only, controlled wood pellet gasification would raise the health impact by 12% from the base case while controlled wood waste gasification would raise the impact by 133%. By switching from firewood to wood pellets for BC residential heating, the primary energy consumption and impacts on human health, ecosystem quality and climate change can be reduced by 34%, 95%, 27% and 17%, respectively. Over 90% reduction in external costs can also be achieved. In terms of economic viability, when bulk pellets are to be utilized, switching from firewood to pellet units would be reasonable as long as the unit to be replaced is not a fireplace insert.
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