Because using forest resources to produce biofuels is a new idea, we want to understand the environmental impacts statewide. Our research will allow people to know with some certainty that these proposed actions offer an environmental benefit relative to fossil fuels.

Research question

 The central research questions in this project are: (1) what steps in the forest feedstock supply chain, cultivation, harvesting, or transportation, consume the most energy and produce the most emission of greenhouse gasses; and (2) what effects do new technologies in this supply chain have on improving environmental performance?  Our role in this project is to serve as a sort of “environmental consultant” to the other projects.  We want to calculate how much energy is used, and how many greenhouse gasses are emitted, in all of the activities involved in the growth, harvest, and transport of all of the biomass to be used to produce cellulosic ethanol.  We want to make sure that the environmental benefit of producing this homegrown ethanol is not overshadowed by all of the activities needed to produce the ethanol. Other work in the literature has shown that cellulosic ethanol does reduce greenhouse gas emissions compared to an equivalent amount of fossil fuel, but we want to compile data specific to Michigan to show that the use of cellulosic ethanol would be a significant environmental improvement.

Approach

To enable supply chain modelers to account for environmental impacts of potential biofuels projects in the state of Michigan, we compiled data related to energy use and greenhouse gas emissions. We investigated the activities and inputs related to all types of forest biomass (roundwood, residue collection, plantations) and tracked activities through all stages of growth, harvest, and transport to a hypothetical biomass processing facility. Fossil fuel emissions and energy use for each activity were compiled, using national databases, peer-reviewed journals relevant to our situation, and local data from foresters, loggers, and truckers. All of this data will be related to one consistent unit – one ton of green timber delivered to the plant gate – in order to standardize all of the contributions from forestry operations, transportation, and other inputs.

Progress and Results

Several different equipment configurations and operating scenarios for roundwood harvesting were considered. Results indicated that a full processor / forwarder is the best choice of harvesting equipment configuration due to relatively low inputs and high reported productivity, although the burdens of harvesting depend strongly on the intensity of harvest being conducted. Multimodal truck + rail transport had roughly 2X lower environmental burdens than typical log truck transport, which was directly related to the increased fuel efficiency of rail transport.

Final project report:

Understand Life Cycle Environmental Impacts of System Alternatives from Forest to Factory Gate

Additional publications:

• Zhang, F., Handler, R., Johnson, D.M., and Shonnard, D.R. (April 2011) Comparative Analysis of Life Cycle Greenhouse Gas Emissions of Supply Chains for Biofuel and Fossil Fuel Production, paper accepted for the Proceedings of the 2011 Production and Operations Management Society (POMS) Conference, Reno, NV. Available here.