Browsing by Subject "switchgrass"

Now showing 1 - 3 of 3
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    Energizing the Landscape: An analysis of switchgrass production costs, commodity crop economics, and nascent gasification technologies in the United States.
    (2014-08) Nickerson, Thomas
    The United States has set ambitious goals for bioenergy that, if met, would require the widespread production of additional sources of biomass on the landscape. In this dissertation, I explore three important economic aspects of the development of the bioenergy industry, namely switchgrass production costs, competition between switchgrass crops and existing commodity crops, and the use of biomass in emerging energy technologies. First, I derive near-term production costs, returns, and profitability of switchgrass (Panicum virgatum), a perennial bioenergy crop, across a region spanning 14 states. Costs vary across the region, ranging from less than $300 ha-1 to more than $1,400 ha-1, yet switchgrass for bioenergy may be profitable in certain locations with commoditized switchgrass prices at or above $50 Mg-1. Second, I describe the financial profile of the two most prevalent commodity crops grown in the United States, corn and soybeans. I find both crops experience an increase in production costs across the entire study period, but these increases are outpaced by commodity prices, ultimately leading to higher operating profit margins. Furthermore, approximately half of all major corn and soybean producing counties have experienced, in at least one year from 2005 to 2011, a policy inefficiency in which crop insurance overcompensates for the loss of crops, which hinders the introduction of dedicated bioenergy crops on the landscape. Third, I assess the viability of solar-heated gasification systems and find that given current energy market conditions, financial incentives such as tax credits, bond yield reductions, or price subsidies would be necessary to generate a positive return over the life of facilities. In total, bioenergy in the United States will face substantial hurdles and will need to overcome industrial inertia in the agriculture and energy sectors. However, with the correct tools and incentives, it may be possible for bioenergy from switchgrass to become an increasingly important piece of the United States energy profile.
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    Switching to Switchgrass: Pathways and consequences of bioenergy switchgrass entering the Midwestern landscape
    (2015-08) Krohn, Brian
    The US has the ambitious goal of producing 60 billion liters of cellulosic biofuel by 2022. Researchers and US Federal Agencies have identified switchgrass (Panicum virgatum L.) as a potential feedstock for next generation biofuels to help meet this goal because of its excellent agronomic and environmental characteristics. With national policy supporting the development of a switchgrass to bioenergy industry two key questions arise: 1) Under what economic and political conditions will switchgrass enter the landscape? 2) Where on the landscape will switchgrass be cultivated given varying economic and political conditions? The goal of this dissertation is to answer these questions by analyzing the adoption of switchgrass across the upper Midwestern US at a high spatial resolution (30m) under varying economic conditions. In the first chapter, I model switchgrass yields at a high resolution and find considerable variability in switchgrass yields across space, scale, time, and nitrogen management. Then in the second chapter, I use the spatial results from chapter one to challenge the assumption that low-input (unmanaged) switchgrass systems cannot compete economically with high-input (managed) switchgrass systems. Finally, in the third chapter, I evaluate the economic and land quality conditions required for switchgrass to be competitive with a corn/soy rotation. I find that switchgrass can displace low-yielding corn/soy on environmentally sensitive land but, to be competitive, it requires economic support through payments for ecosystem services equal to $360 ha-1. With a total expenditure of $4.3 billion annually for ecosystem services, switchgrass could displace corn/soy on 12.2 million hectares of environmentally sensitive land and increase ethanol production above that from the existing corn by 20 billion liters. Thus, ecosystem services can be an effective means of meeting both bioenergy and environmental goals. Taking the three chapters in aggregate it is apparent that switchgrass faces many challenges before it will be adopted on the landscape and it is unlikely it will be adopted under traditional market pricing. However, switchgrass does have considerable potential to help meet the US’s bioenergy and environmental goals through new mechanisms, such as payments for ecosystem services potentially coupled with low-input management systems.
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    Translocating Panicum virgatum L.: Performance, Community Impact and Competitive Outcome
    (2015-08) Flint, Shelby
    This dissertation elucidates the effects that selection history and foundation-number have on switchgrass vigor and competitiveness, and plant community diversity and performance, so as to help inform germplasm-sourcing decisions for grassland reconstructions. Chapter 1 examines the effects that selection history had on switchgrass stand density, persistence, and aboveground biomass, and tested whether multi-foundation strains performed consistently across four sites. Cultivar and ecotype biomass did not differ and while cultivars exceeded ecotypes in stand density, cultivar persistence was lower due to self-thinning. Strains’ geographic origin was related positively to stand density and negatively to biomass across evaluation sites. I found no evidence that multi-foundation strains performed more consistently across sites than did single-foundation strains. Collectively, these results suggest that cultivars may colonize adjacent areas through strong propagule pressure exerted by dense stands but colonization would not necessarily result in extreme dominance. Switchgrass establishment and persistence vary through the interaction of geographic origin and reconstruction location. Chapter 2 examines the effects of switchgrass selection history and foundation-number on plant community diversity and switchgrass performance in experimental prairie plots that harbored cultivars or ecotypes. The effects of switchgrass characteristics on community metrics were variable and generally small. Cultivars exceeded ecotypes in establishment, third-year stand density, and biomass but effects were modest and site-contingent. My results suggest that modestly stronger performance by cultivars does not translate into adverse effects on plant diversity. Under strong competition from weeds, switchgrass does not persist. Switchgrass is unlikely to naturalize in reconstruction-adjacent areas that are heavily vegetated. Chapter 3 evaluates competitive response and effect of juvenile switchgrass cultivars, ecotypes, and wild collections when grown with heterospecifics commonly found in reconstructed grasslands. Height and biomass were generally lowest in wild collections and similar for ecotypes and cultivars. However, belowground biomass in cultivars exceeded that of the other groups. All switchgrass groups were smallest and allocated the most to aboveground tissues when grown with an annual forb. Cultivar biomass was greatest when grown with a perennial C3 grass. I found little evidence of variation among switchgrass groups in competitive effect; however, competitor belowground biomass was lowest when grown with cultivars. History of selection in switchgrass contributes to intraspecific differences in competitive outcomes and should be taken into account when sourcing germplasm for reconstructed grasslands. Collectively, these chapters suggest that switchgrass is unlikely to become overly dominant within reconstructed grasslands or to pose an invasive threat to adjacent vegetative areas. Artificial selection has increased cultivar performance relative to ecotypes and wild collections but the differences are contingent on site conditions and competition regime. Discussion of the risks posed by translocated switchgrass populations should shift away from invasiveness and focus on the impacts of gene-flow between translocated and wild populations.