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This research combines Geographic Information Systems (GIS) and Mixed Integer Programming (MIP) model to determine feedstock supply, preprocessing facility, and biorefinery locations at a highly resolved spatial scale with the objective of meeting a large-scale annual biofuel production and demand goal for Tennessee, USA. Simultaneous determination of this supply chain network using MIP is computationally expensive. Memory limitation of typical personal computers constrain the network problem. High Performance Computing environments may require days to solve, and without any assurance of a feasible solution. This paper proposes a two-stage optimization procedure to overcome these computational challenges while maintaining theoretical consistency with conventional firm location theory paradigms. The two-stage procedure assumes that firms first identify biorefinery locations with comparative advantage in terms of supplying biomass. Step two entails determining if costs can be lowered with the addition of preprocessing facilities, and their optimal location relative to the biorefinery sites. In contrast, a single step optimization procedure siting multiple biorefineries and concomitantly preprocessing units and biomass supply areas assumes a different strategy for a single firm. Results suggest that the two-stage optimization approach is able to identify a feasible solution of multiple feedstock areas, feedstock preprocessing and fuel production locations using high-resolution spatial layers over a relatively large geographic region in a fraction of the computer resources required to solve a single, simultaneous location problem. The optimal supply chain network solutions generated from the two-stage and single simultaneous approaches are different. The absolute difference in the smaller scaled models’ objective values is less than 1%. [ABSTRACT FROM AUTHOR]

Producing renewable fuel from dedicated energy crops, such as switchgrass, has the potential to generate localized environmental benefits. This study uses high-resolution spatial data for west Tennessee to quantify the effects of producing switchgrass for cellulosic ethanol on the grey water footprint (GWF), or the amount of freshwater needed to dilute nitrate leachate to a safe level, relative to existing agricultural production. In addition, the estimated cost and GWF are incorporated in a mixed-integer multi-objective optimization model to derive the efficient frontier of the feedstock supply chain and determine a switchgrass supply chain that achieves the greatest reduction in GWF at the lowest cost. Results suggest that background nitrate concentration in ambient water and the types of agricultural land converted to switchgrass production influence the extent of the GWF. The average GWF of switchgrass in the study area ranges between 131.8 L L −1 and 145.9 L L −1 of ethanol, which falls into the range of estimated GWF of other lignocellulosic biomass feedstock in the literature. Also, the average cost of reducing GWF from the feedstock supply chain identified by the compromise solution method is $0.94 m −3 in the region. A tradeoff between biofuel production costs and reduced nitrate loading in groundwater is driven by differences in the agricultural land converted to feedstock production. Our findings illustrate the energy-water-food nexus in the development of a local bioenergy sector and provide a management strategy associated with land use choices for the supply of energy crops. However, the water quality improvements associated with displacing crop with feedstock production in one region could be offset by expanded or more intensive agricultural production in other regions. [ABSTRACT FROM AUTHOR]

This study assesses the supply of switchgrass and miscanthus, in Ontario, Canada, under different biomass prices and supply chain structures, using an integrated economic, biophysical and GIS model, to assess bioenergy policy. In a local, domestic supply chain, 4 million tonnes of baled biomass production per year becomes attractive for transport to the Nanticoke Generation Station at $69/t. For a larger scale export supply chain to Rotterdam in the form of biomass pellets aggregated on the farm, 20 million tonnes of production becomes attractive at approximately $198/t. For an export supply chain with aggregation at the major ports of Ontario, 20 million tonnes of baled biomass product is attractive for shipping to ports, with pellets subsequently transported to Rotterdam, at around $137/t. Higher bale transportation costs mean that agricultural lands closer to ports, but with lower yields, are preferred compared to the on-farm aggregation scenario. Given government incentives to ease the transition between annual and perennial crops and an actual realized demand from the Nanticoke Generation Station for biomass, this supply chain scenario is plausible. However, export scenarios are not attractive due to infrastructure constraints from current pellet processing capacity, and volatile international energy and commodity markets. [ABSTRACT FROM AUTHOR]

The methane yield and microbial community resulting from co-digestion of dairy manure and switchgrass at different mixing ratios [4:0, 3:1, 2:2, 1:3, and 0:4 based on total solids (TS) content] were evaluated. The results indicated that switchgrass is an excellent feedstock for biogas production when co-digested with dairy manure. Mono-digestion of a high dose (>4% TS) of switchgrass led to volatile fatty acid accumulation and process failure, whereas co-digestion of switchgrass and dairy manure could increase the buffering capacity and improve the fermentation efficiency. The optimal mixture ratio of dairy manure and switchgrass was 2:2, with a methane yield that was 39% higher than that obtained by digestion of the individual substrates. The added amount of 8% TS at the 2:2 ratio achieved the highest methane yield of 158.6 mL/g VS, which corresponded to a 1.3-fold increase in the volumetric productivity of methane compared to mono-digestion of 4% TS switchgrass. Quantitative polymerase chain reaction and clone library analyses showed significant differences in the bacterial community resulting from the different co-substrate ratios. Planctomycetes (28%), Chloroflexi (24%), and Bacteroidetes (24%) were the dominant phyla in digesters with a co-substrate ratio of 2:2. [ABSTRACT FROM AUTHOR]

Highlights: [•] We model field-to-biorefinery dedicated energy crop production and delivery cost. [•] We determine cost to produce and deliver switchgrass and forage sorghum biomass. [•] Estimated costs of delivering a flow of switchgrass is less than for forage sorghum. [•] The cost difference is primarily due to differences in harvest costs. [•] Harvest cost are influenced by the length of the harvest window. [ABSTRACT FROM AUTHOR]

Abstract: Bioethanol produced from lignocellulosic feedstock show enormous potential as an economically and environmentally sustainable renewable energy source. Switchgrass (panicum virgatum) is considered as one of the best second generation feedstock for bioethanol production. In order to commercialize the production of switchgrass-based bioethanol, it is essential to design an efficient switchgrass-based bioethanol supply chain (SBSC) and effectively manage the logistics operation. This paper proposes an integrated mathematical model to determine the optimal comprehensive supply chain/logistics decisions to minimize the total SBSC cost by considering existing constraints. A case study based on North Dakota state (ND) in the United States illustrates the application of the proposed model. The results demonstrate that by using only 61% of the available marginal land for production of switchgrass feedstock, 100% of the annual gasoline energy equivalent requirement of ND can be economically and sustainably met from the produced bioethanol. Sensitivity analysis is conducted to provide insights for efficiently managing the entire SBSC and minimizing the total cost. [Copyright &y& Elsevier]

[Display omitted] • Nationwide facility database to meet target cost, quality and quantity for biofuels. • In 2022, 42.8 M dt of corn stover and switchgrass could be accessible nationwide. • An $8/dt reduction in delivery cost could reduce total accessible biomass by 67%. • KS, NE, SD and TX were identified as potential states with a strong biofuel economy. • CO, AL, GA, MN, MS and SC could greatly benefit from a nationwide depot network. The sustainability of the biofuel industry depends on the development of a mature conversion technology on a national level that can take advantage of the economies of scale: the nth-plant. Defining the future location and supply logistics of conversion plants is imperative to ultimately transform the nation's renewable biomass resources into cost-competitive, high-performance feedstock for production of biofuels and bioproducts. Since the US has put restrictions on production levels of conventional biofuels from edible resources, the nation needs to plan for the widespread accessibility and development of the cellulosic biofuel scenario. Conventional feedstock supply systems will be unable to handle cellulosic biomass nationwide, making it essential to expand the industry with an advanced feedstock supply system incorporating a distributed network of preprocessing depots and conversion plants, or biorefineries. Current studies are mostly limited to designing supply systems for specific regions of the country. We developed a national database with potential locations for depots and biorefineries to meet the nation's target demand of cellulosic biofuel. Blended feedstock with switchgrass and corn stover (harvested by either a two- or three-pass method) are considered in a Mixed Integer Linear Programming model to deliver on-spec biomass that considers both, a desired quantity and quality at the biorefinery. The model solves for a network of varying size depots that supply to biorefineries of 725,000 dry tons/year. A total delivered feedstock cost that is less than $79.07/dry tons (2016$) is evaluated for years 2022, 2030, and 2040. In 2022, 124 depots and 59 biorefineries could be supplied with 42.8 million dt of corn stover and switchgrass. In 2030 and 2040, the total accessible biomass could increase to 215% and 393% respectively when compared to 2022. However, an $8/dry tons reduction in targeted delivery cost could reduce total accessible biomass by 67%. Kansas, Nebraska, South Dakota and Texas were identified as potential states with a strong biofuel economy given that they had six or more biorefineries located in all scenarios. In some scenarios, Colorado, Alabama, Georgia, Minnesota, Mississippi and South Carolina would greatly benefit from a depot network as these could only deliver to a biorefinery in a nearby state. To elaborate the impact of a nationwide consideration, the findings were compared with existing literature for different US regions. We also present results for biorefinery capacities that are double, triple and quadruple in size. [ABSTRACT FROM AUTHOR]