Heidi L. Sieverding

Nitrogen rate and landscape impacts on life cycle energy use and emissions from switchgrass-derived ethanol

Switchgrass‐derived ethanol has been proposed as an alternative to fossil fuels to improve sustainability of the US energy sector. In this study, life cycle analysis (LCA) was used to estimate the environmental benefits of this fuel. To better define the LCA environmental impacts associated with fertilization rates and farm‐landscape topography, results from a controlled experiment were analyzed. Data from switchgrass plots planted in 2008, consistently managed with three nitrogen rates (0, 56, and 112 kg N ha−1), two landscape positions (shoulder and footslope), and harvested annually (starting in 2009, the year after planting) through 2014 were used as input into the Greenhouse gases, Regulated Emissions and Energy use in transportation (GREET) model. Simulations determined nitrogen (N) rate and landscape impacts on the life cycle energy and emissions from switchgrass ethanol used in a passenger car as ethanol–gasoline blends (10% ethanol:E10, 85% ethanol:E85s). Results indicated that E85s may lead to lower fossil fuels use (58 to 77%), greenhouse gas (GHG) emissions (33 to 82%), and particulate matter (PM2.5) emissions (15 to 54%) in comparison with gasoline. However, volatile organic compounds (VOCs) and other criteria pollutants such as nitrogen oxides (NOx), particulate matter (PM10), and sulfur dioxides (SOx) were higher for E85s than those from gasoline. Nitrogen rate above 56 kg N ha−1 yielded no increased biomass production benefits; but did increase (up to twofold) GHG, VOCs, and criteria pollutants. Lower blend (E10) results were closely similar to those from gasoline. The landscape topography also influenced life cycle impacts. Biomass grown at the footslope of fertilized plots led to higher switchgrass biomass yield, lower GHG, VOCs, and criteria pollutants in comparison with those at the shoulder position. Results also showed that replacing switchgrass before maximum stand life (10–20 years.) can further reduce the energy and emissions reduction benefits.

Life-cycle assessment of oilseeds for biojet production using localized cold-press extraction.

As nonfood oilseed varieties are being rapidly developed, new varieties may affect agricultural production efficiency and life-cycle assessment results. Current, detailed feedstock production information is necessary to accurately assess impacts of the biofuel life-cycle. The life-cycle impacts of four nonfood oilseeds (carinata [ L. Braun], camelina [ L. Crantz], canola or rapeseed [ L.], and sunflower [ L.]) were modeled using Argonne National Laboratorys GREET model to compare feedstocks for renewable biojet production using cold-press oil extraction. Only feedstock-related inputs were varied, allowing isolation of feedstock influence. Carinata and camelina performed slightly better than other oilseed crops at most product stages and impact categories as a result of current, low-input agricultural information and new feedstock varieties. Between 40 to 50% of SO and NO emissions, ∼25% of greenhouse gas (GHG) emissions, and ∼40% of total energy consumption for the biojet production impact occurred during feedstock production. Within the first standard deviation, total well-to-tank emissions varied between ∼13% (GHG) and ∼35% (SO) for all feedstocks emphasizing the importance of accurate agricultural production information. Nonfood oilseed feedstock properties (e.g., oil content, density) and agricultural management (e.g., fertilization, yield) affect life-cycle assessment results. Using biofuels in feedstock production and focusing on low-impact management would assist producers in improving overall product sustainability.

Meta-Analysis of Soybean-based Biodiesel

Biofuel policy changes in the United States have renewed interest in soybean [ (L.) Merr.] biodiesel. Past studies with varying methodologies and functional units can provide valuable information for future work. A meta-analysis of nine peer-reviewed soybean life cycle analysis (LCA) biodiesel studies was conducted on the northern Great Plains in the United States. Results of LCA studies were assimilated into a standardized system boundary and functional units for global warming (GWP), eutrophication (EP), and acidification (AP) potentials using biodiesel conversions from peer-reviewed and government documents. Factors not fully standardized included variations in NO accounting, mid- or end-point impacts, land use change, allocation, and statistical sampling pools. A state-by-state comparison of GWP lower and higher heating values (LHV, HHV) showed differences attributable to variations in spatial sampling and agricultural practices (e.g., tillage, irrigation). The mean GWP of LHV was 21.1 g·CO-eq MJ including outliers, and median EP LHV and AP LHV was 0.019 g·PO-eq MJ and 0.17 g·SO-eq MJ, respectively, using the limited data available. An LCA case study of South Dakota soybean-based biodiesel production resulted in GWP estimates (29 or 31 g·CO-eq MJ; 100% mono alkyl esters [first generation] biodiesel or 100% fatty acid methyl ester [second generation] biodiesel) similar to meta-analysis results (30.1 g·CO-eq MJ). Meta-analysis mean results, including outliers, resemble the California Low Carbon Fuel Standard for soybean biodiesel default value without land use change of 21.25 g·CO-eq MJ. Results were influenced by resource investment differences in water, fertilizer (e.g., type, application), and tillage. Future biofuel LCA studies should include these important factors to better define reasonable energy variations in regional agricultural management practices.

Lifecycle Assessment Analysis of Engineered Stormwater Control Methods Common to Urban Watersheds

AbstractBest management practice (BMP) selection typically focuses on economic costs and management criteria. Generally, there is very little consideration of lifecycle assessment (LCA)-determined environmental impacts (LCA impacts) associated with management practice implementation and operation, although the inclusion of LCA considerations are becoming increasingly common within state governments and industries as part of sustainability initiatives. LCA modeling provides an evaluation of the environmental impacts of a product or process in a cradle to grave scenario following ISO 140440 protocol. LCA can provide value in preliminary decision making for construction of sustainable stormwater management structures. To assist in that effort, the LCA impacts of typical upper Midwest U.S. urban stormwater management scenarios were evaluated. Primary, traditional structures (porous detention, sand filtration basins) were considered both as stand-alone systems and as systems coupled with green BMPs (rain garde...

Eco-Efficiency Model for Evaluating Feedlot Rations in the Great Plains, United States.

Environmental impacts attributable to beef feedlot production provide an opportunity for economically linked efficiency optimization. Eco-efficiency models are used to optimize production and processes by connecting and quantifying environmental and economic impacts. An adaptable, objective eco-efficiency model was developed to assess the impacts of dietary rations on beef feedlot environmental and fiscal cost. The hybridized model used California Net Energy System modeling, life cycle assessment, principal component analyses (PCA), and economic analyses. The model approach was based on 38 potential feedlot rations and four transportation scenarios for the US Great Plains for each ration to determine the appropriate weight of each impact. All 152 scenarios were then assessed through a nested PCA to determine the relative contributing weight of each impact and environmental category to the overall system. The PCA output was evaluated using an eco-efficiency model. Results suggest that water, ecosystem, and human health emissions were the primary impact category drivers for feedlot eco-efficiency scoring. Enteric CH emissions were the greatest individual contributor to environmental performance (5.7% of the overall assessment), whereas terrestrial ecotoxicity had the lowest overall contribution (0.2% of the overall assessment). A well-balanced ration with mid-range dietary and processing energy requirements yielded the most eco- and environmentally efficient system. Using these results, it is possible to design a beef feed ration that is more economical and environmentally friendly. This methodology can be used to evaluate eco-efficiency and to reduce researcher bias of other complex systems.

Historical sediment mercury deposition for select South Dakota, USA, lakes: implications for watershed transport and flooding

PurposeSelect South Dakota, USA water bodies, including both natural lakes and man-made impoundments, were sampled and analyzed to assess mercury (Hg) dynamics and historical patterns of total Hg deposition.Materials and methodsSediment cores were collected from seven South Dakota lakes. Mercury concentrations and flux profiles were determined using lead (210Pb) dating and sedimentation rates.Results and discussionMost upper lake sediments contained variable heavy metal concentrations, but became more consistent with depth and age. Five of the seven lakes exhibited Hg accumulation fluxes that peaked between 1920 and 1960, while the remaining two lakes exhibited recent (1995–2009) Hg flux spikes. Historical sediment accumulation rates and Hg flux profiles demonstrate similar peak and stabilized values. Mercury in the sampled South Dakota lakes appears to emanate from watershed transport due to erosion from agricultural land use common to the Northern Great Plains.ConclusionsFor sampled South Dakota lakes, watershed inputs are more significant sources of Hg than atmospheric deposition.

Biodiesel Supply Chain Optimization Modeled with Geographical Information System (GIS) and Mixed-Integer Linear Programming (MILP) for the Northern Great Plains Region

Drought-tolerant, industrial oilseeds such as Camelina sativa (camelina) grown on marginal land are being considered as feedstock alternatives to meet the increasing biofuel demand and reduce the dependency on water and food resources. However, crops grown on rural, marginal lands are not well-connected with transportation networks and biofuel plants. Transportation routes and biofuel plant development should be optimized for sustainable biofuel development. This study aimed at developing a supply chain optimization model for biodiesel produced from camelina oilseed. A mixed integer linear programming (MILP) model associated with geographic information system (GIS) was built. Three echelons of camelina oilseed supply, biodiesel production, and biodiesel and by-product (livestock meal) demand were considered to optimize the numbers, locations, and capacities of new plants, transportation routes, and the utilization rate of existing plants at a minimum cost. A case study was conducted for the northern Great Plains (NGP) region of Montana, South Dakota, and North Dakota. Transportation cost compared to plant construction cost was a decisive factor in supply chain configuration. The model developed in this study simulates minimum cost transportation routes directly through the GIS network analysis, which is differentiated from other studies analyzing the shortest routes in GIS and calculating their transportation costs in models. This is beneficial in seeking economic routes which incorporate multiple modes for regions having a spartan infrastructure.

Technology enabled curriculum for a first-year engineering program

For the past three years, all first year engineering students at the South Dakota School of Mines & Technology have enrolled in a common introduction to engineering course. The course features a common curriculum contained on a course CD, utilization of technology tools, an engineering design project, and introduction to technical writing. All sections of the course are taught in a single classroom that is set up with tables and equipped with wireless notebook PCs. Technology tools are focused on collection, manipulation, and presentation of data using electronic portfolios, a permanent digital archive, spreadsheet tools, and data loggers. The use of spreadsheets for solving engineering problems is illustrated through example problems and several tutorial exercises that are both contained on the curricular CD. Portable data loggers are utilized in lab projects for collecting data that is then manipulated and analyzed on a spreadsheet. The design project requires students teams to function within specified design parameters, construct a simple device that is then used to collect data, analyze the data, and present the results both in an oral presentation and a formal technical document. In this paper, examples of technology uses in the curricular materials, engineering problems, and design projects used will be illustrated and discussed.