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Simulation modeling of forest biomass operations and harvest residue moisture content Pledger, Sean

Abstract

In order to limit the effects of anthropogenic climate change the world is moving away from the use of fossil fuels as a primary energy source. Bioenergy is expected to form a substantial contribution to this transitional strategy. In order to increase bioenergy production, underutilized forest harvest residues are being targeted as a fuel source. Even with favorable policies in place to encourage their use, the processing and collection of these previously disregarded resources is often prohibitively expensive. Quality factors such as material moisture content also impact the viability of harvest residues for fuel purposes. As a result, careful operational planning is of great importance to sourcing high quality, economically feasible biomass. To gain a better understanding of the forest biomass supply chain, a simulation model was developed for a case study located in coastal British Columbia, Canada. A seasonal moisture content trend was identified and incorporated to help develop a strategy for sourcing high quality materials. It was found for BC’s coastal temperate rainforest environment that by delaying biomass collection until the second summer after timber harvest an average delivered moisture content of 28% can be achieved rather than 38% is operations proceed in the first summer. This reduction in delivered moisture content also led to a decrease in delivered cost from $72.08 to $67.95 per oven dried tonne. Trucking and equipment configurations were also examined to identify least cost approaches to biomass collection under varying conditions. Comparing high productivity and low productivity equipment configurations showed a $26.08/ODT cost increase when switching to less productive equipment. By employing an electric centralized grinder transporting unprocessed harvest residues, costs were shown to decrease for all cutblock groups with a cycle time of less than four and a half hours. Least cost fleet size was found to be largely dependent on the average cycle time to the biomass source. And the volume of available biomass at a given cutblock was found to have an impact on delivered costs with a 20% increase in biomass volume resulting in a cost decrease of greater than $2/ODT.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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