The Feasibility of Growing Switchgrass in China for Lignocellulosic Ethanol Production

Switchgrass (Panicum virgatum L.) is a perennial plant species native to the United States that is capable of adapting to a wide variety of geographic and climate conditions. There are two ecotypes of switchgrass: lowland varieties which favor areas with higher rainfall and longer growing seasons and upland varieties which favor areas with cooler and drier climate conditions with shorter growing seasons. Switchgrass has the capacity to become a significant bioenergy feedstock for lignocellulosic ethanol conversion. The purpose of this dissertation is to determine which regions in China are suitable for switchgrass production, estimate potential biomass yield, and examine the effects of predicted climate change scenarios at the end of the 21st century on potential yields in China. To accomplish these goals, two ecological niche models (Maxent and GARP) are implemented based on known switchgrass presence data throughout the United States to ascertain which regions in China have suitable habitats for its growth. Multiple linear regression analysis was performed on a comprehensive database of 1,190 switchgrass field trials in 39 separate locations across the United States to build a model that estimates potential switchgrass yields across China. Future climate projections (2070 – 2099) from the Hadley Centre Coupled Model, version 3 (HadCM3) global circulation model (GCM) are employed in the multiple linear regression model to make switchgrass yield estimations for the end of the century. The ecological niche modeling results reveal China has large areas of suitable habitat for switchgrass development. The multiple linear regression analysis demonstrates that China has the potential to produce large quantities of switchgrass, even more so than in the United States; however, analysis of the impact of climate change by the end of the 21st Century indicates that warmer temperatures will result in lower yields on average, a substantial reduction in suitable habitat for lowlands, and an expanded habitat range for upland ecotypes. This dissertation concludes that switchgrass should be considered a viable plant species to serve as a bioenergy feedstock for lignocellulosic ethanol production in China, and the results herein offer guidelines regarding optimal regions in the country for switchgrass production

The Feasibility of Growing Switchgrass in China for Lignocellulosic Ethanol Production

Switchgrass (Panicum virgatum L.) is a perennial plant species native to the United States that is capable of adapting to a wide variety of geographic and climate conditions. There are two ecotypes of switchgrass: lowland varieties which favor areas with higher rainfall and longer growing seasons and upland varieties which favor areas with cooler and drier climate conditions with shorter growing seasons. Switchgrass has the capacity to become a significant bioenergy feedstock for lignocellulosic ethanol conversion. The purpose of this dissertation is to determine which regions in China are suitable for switchgrass production, estimate potential biomass yield, and examine the effects of predicted climate change scenarios at the end of the 21st century on potential yields in China. To accomplish these goals, two ecological niche models (Maxent and GARP) are implemented based on known switchgrass presence data throughout the United States to ascertain which regions in China have suitable habitats for its growth. Multiple linear regression analysis was performed on a comprehensive database of 1,190 switchgrass field trials in 39 separate locations across the United States to build a model that estimates potential switchgrass yields across China. Future climate projections (2070 – 2099) from the Hadley Centre Coupled Model, version 3 (HadCM3) global circulation model (GCM) are employed in the multiple linear regression model to make switchgrass yield estimations for the end of the century. The ecological niche modeling results reveal China has large areas of suitable habitat for switchgrass development. The multiple linear regression analysis demonstrates that China has the potential to produce large quantities of switchgrass, even more so than in the United States; however, analysis of the impact of climate change by the end of the 21st Century indicates that warmer temperatures will result in lower yields on average, a substantial reduction in suitable habitat for lowlands, and an expanded habitat range for upland ecotypes. This dissertation concludes that switchgrass should be considered a viable plant species to serve as a bioenergy feedstock for lignocellulosic ethanol production in China, and the results herein offer guidelines regarding optimal regions in the country for switchgrass production

Hydrologic and water quality impacts from perennial crop production on marginal lands

Marginal lands are proposed as a viable option for producing biofeedstocks as these lands are not heavily engaged in agricultural production or may not be suitable for intensive row-crop food/feed production. However, meeting biofeedstock production goals will require large amount of marginal lands and the unintended consequences of producing biofeedstocks on marginal lands are not fully clear. The overall goal of this study was to evaluate the productivity of biofeedstocks on marginal lands and the potential impacts on hydrologic and water quality processes from the land use conversion. This study was conducted in the Upper Mississippi River Basin (UMRB). First, the suitability of marginal lands in this region was evaluated for the growth of three candidate biofeedstock crops, switchgrass, Miscanthus and hybrid poplar. The evaluation was conducted using a fuzzy logic based land suitability evaluation method. Then, the simulation of switchgrass and Miscanthus growth during their establishment periods in the Soil and Water Assessment Tool (SWAT) model was improved. Finally, the model was used to evaluate the impacts on hydrologic and water quality processes due to production of switchgrass and Miscanthus on marginal lands in the UMRB region. The results indicated that 23% of the UMRB area included marginal lands. Among these lands, 40% of them were poorly suitable for the production of biofeedstock crops. Biofeedstocks produced from these marginal lands could be converted to biofuels that contributed 14 to 25% of the 132 billion liter biofuel goals set by the Energy Independence and Security Act (EISA) 2007. The model simulation results indicated that producing perennial biofeedstock crops on marginal land would reduce annual stream flow by 20% and 29% and sediment load by 26% to 35% at the watershed outlet. The reduction was less during the establishment periods of perennial grasses (first 2 to 3 years of switchgrass and 2 to 4 years of Miscanthus) than during the post establishment periods. The results of this study indicated that marginal land in the UMRB region could be a viable choice of land resources for biofuel development and could be used to produce almost one quarter of biofuel production goals. At the same time, water quality in the watershed could be improved. The information could be used by stakeholders to create regional biofuel development and watershed management plans

Corn, Wheat, And Switchgrass Biomass Production In The Northern Plains: Evaluating Opportunities And Tradeoffs

The US government has mandated the annual usage of 61 GL of cellulosic biofuel by 2022. Cellulosic residues from annual crops, such as corn (Zea mays L.) and wheat (Triticum aestivum L. ssp. aestivum) represent a potential source of cellulosic biomass. Another source is the production of cellulosic bioenergy crops. Switchgrass (Panicum virgatum L.) was identified as a model biomass crop by the US Department of Energy in 1992, features the most advanced agronomic development among herbaceous perennial bioenergy feedstock candidates, and is widely adapted across North America. In three interconnected studies considering a 99-county area of the eastern Dakotas and western Minnesota, this dissertation characterizes the existing resource base of corn and wheat cellulosic biomass, estimates the biomass prices necessary for switchgrass to be competitive with collection of existing corn and wheat biomass, and estimates the necessary incentives for switchgrass to supplant sufficient corn or wheat area to offset recent grassland-to-cropland conversions observed within the study region. An improved parameterization of upland switchgrass ecotypes for the ALMANAC (Agricultural Land Management Alternative with Numerical Assessment Criteria) model was shown to predict multiyear-average yields with an RMSE of 1.95 Mg ha-1 and PBIAS of 7.2%. Using moderate-resolution regional inputs, ALMANAC estimated county-scale multiyear-average corn yields with an RMSE of 0.71 Mg ha-1 and PBIAS of 1.9%, and corresponding wheat yields with an RMSE of 0.28 Mg ha-1 and PBIAS of 2.8%. Corn and wheat can supply up to 16.48 Tg of biomass annually within estimated biorefinery collection areas, at a biomass price of $60 Mg-1 or less. Switchgrass would require biomass prices of$60 to $180 Mg-1 to supplant corn or wheat production, dependent on establishment and production cost assumptions. Annual payments of$120 to $290 million would encourage sufficient switchgrass production to offset recent grassland-to-cropland conversions in the study region, and can be strategically directed to maximize the environmental benefits of switchgrass production

Effect of bioenergy crops and fast growing trees on hydrology and water quality in the Little Vermilion River Watershed

Energy security and sustainability require a suite of biomass crops, including woody species. Short rotation woody crops (SRWCs) such as Populus have great potential as biofuel feedstocks. Quantifying biomass yields of bioenergy crop and hydrologic and water quality responses to growth is important should it be widely planted in the Midwestern U.S. Subsurface tile drainage systems enable the Midwest area to become highly productive agricultural lands, but also create environmental problems like nitrate-N contamination of the water it drains. The Soil and Water Assessment Tool (SWAT) has been used to model watersheds with tile drainage, but the new tile drainage routine in SWAT2012 has not been fully tested. The objectives of this study were to develop algorithms and growth parameters of Populus in Agricultural Land Management Alternative with Numerical Assessment Criteria (ALMANAC) and SWAT models, compare performance of tile drainage routines in SWAT2009 and SWAT2012 in simulating tile drainage, and simulate biomass yields of bioenergy crops and the impacts of their impacts on water quantity and quality for a typical tile-drained watershed in the Midwest USA. The functional components and parameters of hybrid poplar Tristis #1 (Populus balsamifera L. × P.tristis Fisch) and eastern cottonwood (Populus deltoides Bartr.) were determined, and related algorithms improved in ALMANAC and SWAT based on improved simulation of leaf area, plant biomass and biomass partitioning. Long-term (1991-2003) field site and river station data from the Little Vermilion River (LVR) watershed in Illinois were used to evaluate performance of tile drainage routines in SWAT2009 revision 528 (the old routine) and SWAT2012 revision 615 and 645 (the new routine). Calibrated monthly tile flow, surface flow, nitrate in tile and surface flow, sediment and annual corn and soybean yield results at field sites, and flow, sediment load and nitrate load at the river station for the old and new tile drainage routines were compared with observed values. Crop residue from corn stover, perennial grasses, switchgrass and Miscanthus, and hybrid poplar trees were considered as potential bioenergy crops for the LVR watershed. SWAT2012 (Revision 615) with the new tile drainage routine (DRAINMOD routine) and improved perennial grass and tree growth simulation was used to model long-term annual biomass yields, flow, tile flow, sediment load, total nitrogen, nitrate load in flow, nitrate in tile flow, soluble nitrogen, organic nitrogen, total phosphorus, mineral phosphorus and organic phosphorus under various bioenergy scenarios in the LVR watershed. Simulated results from different bioenergy crop scenarios were compared with those from the baseline. Tree growth calibration and validation results showed that improved algorithms of leaf area index (LAI) and biomass simulation and suggested values and potential parameter range for hybrid poplar Tristis #1 and Eastern cottonwood ( Populus deltoides Bartr.) were reasonable, and performance of the modified ALMANAC in simulating LAI, aboveground biomass and root biomass of Populus was good. Performance of the modified SWAT simulated hybrid poplar LAI and aboveground woody biomass (PBIAS: -57 ~ 7%, NSE: 0.94 ~ 0.99, and R2: 0.74 ~ 0.99), and cottonwood aboveground biomass, seasonal mean runoff, mean sediment, mean nitrate-N and total nitrate-N were satisfactory (PBIAS: -39 ~ 11%, NSE: 0.86 ~ 0.99, and R2: 0.93 ~ 0.99). Additionally, tile drainage calibration and validation results indicated that the new routine provides acceptable simulated tile flow (NSE = 0.50 ~ 0.68), and nitrate in tile flow (NSE = 0.50 ~ 0.77) for field sites, while the old routine simulated tile flow (NSE = -0.77~ -0.20) and nitrate in tile flow (NSE = -0.99 ~ 0.21) for the field site with constant tile spacing were unacceptable. The new modified curve number calculation method in revision 645 (NSE = 0.56 ~ 0.82) better simulated surface runoff than revision 615 (NSE = -5.95 ~ 0.5). Bioenergy crop simulation results showed that 38% corn stover removal (66,439 Mg/yr) with combination of Miscanthus both on highly erodible areas and marginal land (19,039 Mg/yr) provided the highest biofeedstock production. Flow, tile flow, erosion and nutrient losses were slightly reduced under bioenergy crop scenarios of Miscanthus, switchgrass, and hybrid poplar on highly erodible areas, marginal land and marginal land with forest. The increase in sediment load and nutrient losses resulting from corn stover removal could be offset under scenarios with various combinations of bioenergy crops. Corn stover removal with bioenergy crops both on highly erodible areas and marginal land could provide more biofuel production relative to the baseline, and was beneficial to hydrology and water quality at the watershed scale. The modified ALMANAC and SWAT can be used for biofeedstock production modeling for Populus. The modified SWAT model can be used for Populus biofeedstock production modeling and hydrologic and water quality response to its growth. The improved algorithms of LAI and biomass simulation for tree growth should also be useful for other process based models, such as SWAT, EPIC and APEX. Tile drainage calibration and validation results provided reasonable parameter sets for the old and new tile drainage routines to accurately simulate hydrologic processes in mildly-sloped watersheds. Bioenergy crop simulation results provided guidance for further research on evaluation of bioenergy crop scenarios in a typical extensively tile-drained watershed in the Midwestern US