Corvallis, OR, United States
Corvallis, OR, United States

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Caputo J.,SUNY College of Environmental Science and Forestry | Balogh S.B.,SUNY College of Environmental Science and Forestry | Volk T.A.,SUNY College of Environmental Science and Forestry | Johnson L.,Leonard Johnson and Associates | And 3 more authors.
Bioenergy Research | Year: 2014

To estimate fossil fuel demand and greenhouse gas emissions associated with short-rotation willow (Salix spp.) crops in New York State, we constructed a life cycle assessment model capable of estimating point values and measures of variability for a number of key processes across eight management scenarios. The system used 445.0 to 1,052.4 MJ of fossil energy per oven-dry tonne (odt) of delivered willow biomass, resulting in a net energy balance of 18.3:1 to 43.4:1. The largest fraction of the energy demand across all scenarios was driven by the use of diesel fuels. The largest proportion of diesel fuel was associated with harvesting and delivery of willow chips seven times on 3-year rotations over the life of the crop. Similar patterns were found for greenhouse gas emissions across all scenarios, as fossil fuel use served as the biggest source of emissions in the system. Carbon sequestration in the belowground portion of the willow system provided a large carbon sink that more than compensated for carbon emissions across all scenarios, resulting in final greenhouse gas balances of -138.4 to -52.9 kg CO2 eq. per odt biomass. The subsequent uncertainty analyses revealed that variability associated with data on willow yield, litterfall, and belowground biomass eliminated some of the differences between the tested scenarios. Even with the inclusion of uncertainty analysis, the willow system was still a carbon sequestration system after a single crop cycle (seven 3-year rotations) in all eight scenarios. A better understanding and quantification of factors that drive the variability in the biological portions of the system is necessary to produce more precise estimates of the emissions and energy performance of short-rotation woody crops. © 2013 Springer Science+Business Media New York.


Bergman R.,U.S. Department of Agriculture | Puettmann M.,WoodLife Environmental Consultants LLC | Taylor A.,University of Tennessee at Knoxville | Skog K.E.,U.S. Department of Agriculture
Forest Products Journal | Year: 2014

Wood products have many environmental advantages over nonwood alternatives. Documenting and publicizing these merits helps the future competitiveness of wood when climate change impacts are being considered. The manufacture of wood products requires less fossil fuel than nonwood alternative building materials such as concrete, metals, or plastics. By nature, wood is composed of carbon that is captured from the atmosphere during tree growth. These two effectssubstitution and sequestration are why the carbon impact of wood products is favorable. This article shows greenhouse gas emission savings for a range of wood products by comparing (1) net wood product carbon emissions from forest cradletomill output gate minus carbon storage over product use life with (2) cradle-to-gate carbon emissions for substitute nonwood products. The study assumes sustainable forest management practices will be used for the duration of the time for the forest to regrow completely from when the wood was removed for product production during harvesting. The article describes how the carbon impact factors were developed for wood products such as framing lumber, flooring, moulding, and utility poles. Estimates of carbon emissions saved per unit of wood product used are based on the following: (1) gross carbon dioxide (CO2) emissions from wood product production, (2) CO2 from biofuels combusted and used for energy during manufacturing, (3) carbon stored in the final product, and (4) fossil CO2 emissions from the production of nonwood alternatives. The results show notable carbon emissions savings when wood products are used in constructing buildings in place of nonwood alternatives. © Forest Products Society 2014.


Lippke B.,University of Washington | Gustafson R.,University of Washington | Venditti R.,North Carolina State University | Steele P.,Mississippi State University | And 5 more authors.
Forest Products Journal | Year: 2012

The different uses of wood result in a hierarchy of carbon and energy impacts that can be characterized by their efficiency in displacing carbon emissions and/or in displacing fossil energy imports, both being current national objectives. When waste wood is used for biofuels (forest or mill residuals and thinnings) fossil fuels and their emissions are reduced without significant land use changes. Short rotation woody crops can increase yields and management efficiencies by using currently underused land. Wood products and biofuels are coproducts of sustainable forest management, along with the other values forests provide, such as clean air, water, and habitat. Producing multiple coproducts with different uses that result in different values complicates carbon mitigation accounting. It is important to understand how the life-cycle implications of managing our forests and using the wood coming from our forests impacts national energy and carbon emission objectives and other forest values. A series of articles published in this issue of the Forest Products Journal reports on the life-cycle implications of producing ethanol by gasification or fermentation and producing bio-oil by pyrolysis and feedstock collection from forest residuals, thinnings, and short rotation woody crops. These are evaluated and compared with other forest product uses. Background information is provided on existing life-cycle data and methods to evaluate prospective new processes and wood uses. Alternative management, processing, and collection methods are evaluated for their different efficiencies in contributing to national objectives. © Forest Products Society 2012.


Lippke B.,University of Washington | Puettmann M.E.,Woodlife Environmental Consultants LLC
Forest Products Journal | Year: 2013

Using wood wastes provides an opportunity to avoid fossil carbon emissions from the combustion of natural gas or other fossil fuels. Using a life-cycle assessment, a new biomass boiler sourced by forest residuals, sawmill residuals, and clean demolition material (CDM) was compared with an existing natural gas boiler for supplying heat to a large-scale district heating system. Potential alternative uses of these feedstocks, such as recycled or reprocessed products, and landfill alternatives were also evaluated for their relative impact on carbon emissions. We found a reduction in emissions from natural gas of 0.62 unit of carbon for every unit of carbon in the wood combusted. Temporary losses of forest carbon after initiating the collection of forest residuals were minimal over a short interval. These losses were more than offset by the joint production of wood products displacing fossil emissions. Carbon mitigation in the Pacific Northwest was increased from 5.5 metric tons/ha/y from the production of forest products with no collection of forest residuals to 6.5 metric tons/ha/y after completing the first rotation, an 18 percent reduction in fossil emissions per hectare of forest. The potential to recycle CDM into wood products may ultimately raise the efficiency in avoiding carbon emissions by 40 to 60 percent, although available wood quality and logistics currently favor use of CDM as biofuel feedstock. In the absence of any "incentives" or value for carbon mitigation, feedstock collection costs relative to low-cost fossil fuel will substantially limit the use of waste woods for biofuel or recycling alternatives. © Forest Products Society 2013.


Puettmann M.E.,WoodLife Environmental Consultants LLC | Lippke B.,University of Washington
Forest Products Journal | Year: 2013

The use of wood waste for heating in urban settings provides an opportunity for communities to reduce annual fossil emissions by directly reducing the amount of fossil fuel used. Life-cycle assessments (LCA) comparing the environmental impacts of alternative processes or products provide the essential information to better understand opportunities for improvement. An LCA was performed on a Seattle, Washington, district heating system that provides thermal energy to a large number of buildings in downtown Seattle. This study presents annual impacts in terms of carbon emissions for heat production generated using a new boiler design fuel mix including wood wastes as well as natural gas. Results are compared with the results from the 100 percent natural gas boiler that was previously used. The LCA includes results from both a lifecycle inventory of all inputs and outputs and a life-cycle impact assessment comparing alternatives. Results show that global warming potential (GWP) was reduced by 57 percent for the mix fuel design boiler compared with an all natural gas boiler. When 100 percent woody biomass is used, the reduction increases to 104 percent. Transportation and collection of feedstocks contributed minimally (8%) to the overall impact, while the combustion life-cycle stage accounted for 92 percent of the total GWP. © Forest Products Society 2013.


Steele P.,Mississippi State University | Puettmann M.E.,WoodLife Environmental Consultants LLC | Penmetsa V.K.,Mississippi State University | Cooper J.E.,Mississippi State University
Forest Products Journal | Year: 2012

As part of the Consortium for Research on Renewable Industrial Materials' Phase I life-cycle assessments of biofuels, lifecycle inventory burdens from the production of bio-oil were developed and compared with measures for residual fuel oil. Bio-oil feedstock was produced using whole southern pine (Pinus taeda) trees, chipped, and converted into bio-oil by fast pyrolysis. Input parameters and mass and energy balances were derived with Aspen. Mass and energy balances were input to SimaPro to determine the environmental performance of bio-oil compared with residual fuel oil as a heating fuel. Equivalent functional units of 1 MJ were used for demonstrating environmental preference in impact categories, such as fossil fuel use and global warming potential. Results showed near carbon neutrality of the bio-oil. Substituting bio-oil for residual fuel oil, based on the relative carbon emissions of the two fuels, estimated a reduction in CO2 emissions by 0.075 kg CO2 per MJ of fuel combustion or a 70 percent reduction in emission over residual fuel oil. The bio-oil production life-cycle stage consumed 92 percent of the total cradle-to-grave energy requirements, while feedstock collection, preparation, and transportation consumed 4 percent each. This model provides a framework to better understand the major factors affecting greenhouse gas emissions related to bio-oil production and conversion to boiler fuel during fast pyrolysis. © Forest Products Society 2012.


Daystar J.,North Carolina State University | Reeb C.,North Carolina State University | Venditti R.,North Carolina State University | Gonzalez R.,North Carolina State University | Puettmann M.E.,WoodLife Environmental Consultants LLC
Forest Products Journal | Year: 2012

The goal of this study was to estimate the greenhouse gas (GHG) emissions and fossil energy requirements from the production and use (cradle-to-grave) of bioethanol produced from the indirect gasification thermochemical conversion of loblolly pine (Pinus taeda) residues. Additional impact categories (acidification and eutrophication) were also analyzed. Of the life-cycle stages, the thermochemical fuel production and biomass growth stages resulted in the greatest environmental impact for the bioethanol product life cycle. The GHG emissions from fuel transportation and process chemicals used in the thermochemical conversion process were minor (less than 1 percent of conversion emissions). The net GHG emissions over the bioethanol life cycle, cradle-to-grave, was 74 percent less than gasoline of an equal energy content, meeting the 60 percent minimum reduction requirement of the Renewable Fuels Standard to qualify as an advanced (second generation) biofuel. Also, bioethanol had a 72 percent lower acidification impact and a 59 percent lower eutrophication impact relative to gasoline. The fossil fuel usage for bioethanol was 96 percent less than gasoline, mainly because crude oil is used as the primary feedstock for gasoline production. The total GHG emissions for the bioethanol life cycle analyzed in this study were determined to be similar to the comparable scenario from the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation model. A sensitivity analysis determined that mass allocation of forest establishment burdens to the residues was not significant for GHG emissions but had significant effects on the acidification and eutrophication impact categories. © Forest Products Society 2012.


Puettmann M.E.,WoodLife Environmental Consultants LLC | Lippke B.,University of Washington
Forest Products Journal | Year: 2012

Using life-cycle inventory production data, the net global warming potential (GWP) of a typical inland Northwest softwood lumber mill was evaluated for a variety of fuel types used as boiler inputs and for electricity generation. Results focused on reductions in carbon emissions in terms of GWP relative to natural gas as the fossil alternative. Woody feedstocks included mill residues, forest residuals, and wood pellets. In all fuel-substitution scenarios, increasing the use of biomass for heat generation decreased GWP. Using woody biofuels for electricity production is somewhat less effective in lowering carbon emissions than when used for heat energy. Heat generation at the mill under the current practice of using about half self-generated mill residues and half natural gas resulted in a 35 percent reduction in GWP over 100 percent natural gas. The greatest reduction in GWP (66%) was from increased use of forest residuals for heat energy, eliminating the use of fossil fuels as a direct heating fuel at the mill. We summarize the results by documenting that greater use of woody biomass for heat energy will reduce carbon emissions over fossil-based fuels. © Forest Products Society 2012.


Budsberg E.,University of Washington | Rastogi M.,University of Washington | Puettmann M.E.,WoodLife Environmental Consultants LLC | Caputo J.,New York University | And 4 more authors.
Forest Products Journal | Year: 2012

We conducted a life-cycle assessment (LCA) of ethanol production via bioconversion of willow biomass crop feedstock. Willow crop data were used to assess feedstock production impacts. The bioconversion process was modeled with an Aspen simulation that predicts an overall conversion yield of 310 liters of ethanol per tonne of feedstock (74 gal per US short ton). Vehicle combustion impacts were assessed using Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) models. We compared the impacts of bioconversion-produced ethanol with those of gasoline on an equivalent energy basis. We found that the life-cycle global warming potential of ethanol was slightly negative. Carbon emissions from ethanol production and use were balanced by carbon absorption in the growing willow feedstock and the displacement of fossil fuel-produced electricity with renewable electricity produced in the bioconversion process. The fossil fuel input required for producing 1 MJ of energy from ethanol was 141 percent less than that from gasoline. More water was needed to produce 1 MJ of ethanol fuel than 1 MJ of gasoline. The life-cycle water use for ethanol was 169 percent greater than for gasoline. The largest contributors to water use were the conversion process itself and the production of chemicals and materials used in the process, such as enzymes and sulfuric acid. © Forest Products Society 2012.


Katers J.F.,University of Wisconsin - Green Bay | Snippen A.J.,University of Wisconsin - Green Bay | Puettmann M.E.,WoodLife Environmental Consultants LLC
Forest Products Journal | Year: 2012

This study summarizes environmental impacts of "premium" wood pellet manufacturing and use through a cradle-tograve life-cycle inventory. The system boundary began with growing and harvesting timber and ended with use of wood pellet fuel. Data were collected from Wisconsin wood pellet mills, which produce wood pellets from a variety of feedstocks. Three groups of manufacturers were identified, those who use wet coproduct, dry coproduct, and harvested timber. Pellet mill data were weight averaged on a per unit basis of 1.0 short ton of "premium" wood pellets, and burdens for all substances and energy consumed were allocated among the products on a 0 percent moisture basis. Wood pellets produced from dry coproduct required 60 percent less energy at the pellet mill. However, when considering all cradle-to-gate energy inputs, producing wood pellets from whole logs used the least energy. Pellets from wet coproduct and dry coproduct used 9 and 56 percent more energy across the life cycle, respectively. This study also compared environmental impacts of residential heating fuels with wood pellet fuel. Environmental impacts were measured on net atmospheric carbon emissions, nonrenewable energy use, and global warming potential (GWP). Assuming "better than break-even" forest carbon management, cordwood and wood pellet fuels emitted 67.3 and 26.6 percent less atmospheric carbon emissions per megajoule of residential heat across the life cycle than natural gas, the best fossil fuel alternative. Cordwood and wood pellets consumed fewer nonrenewable resources than natural gas, which consumed fewer resources than petroleum-based residual fuel oil. However, wood pellet fuels had a smaller GWP and effect on respiratory health because they have more efficient combustion. © Forest Products Society 2012.

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