133,098 research outputs found
Sustainability of Corn Stover Harvest for Biomass
No full textOff-farm demand for crop residues is expected to grow as bioenergy policies become effective. Demand for residues will provide farmers with an additional source of revenue but it may also trigger losses in soil organic carbon and increases in fertilizer application. This study develops a dynamic economic model of stover harvest that permits conceptualization and quantification of these potential tradeoffs. We parameterize our model based on publicly available studies of soil biophysical relationships in the Corn Belt. Under these parameter values and 2010 corn and fertilizer prices harvesting stover is not economically convenient at prices below $53 per dry ton of stover. Results suggest that the rate of stover harvest may be quite sensitive and negatively linked to corn prices, which means that policies favoring the use of stover for biomass may be overridden by further increases in corn price. The negative link between stover harvest and corn prices, while somewhat counterintuitive, is driven by the fact that removal of stover reduces future grain yield (through reductions in soil organic carbon). Results also seem to indicate that, under plausible parameter values, profit maximizing farmers would increase stover supply in response to increases in stover price. However increases in supply are, according to our simulations, associated with (potentially significant) reductions in soil organic carbon (and hence carbon emissions as these are positively linked) and increases in nitrogen application (and potential runoffs). This result suggests that concerns about adverse environmental implications of harvesting stover may be justified, and more precise quantification of environmental tradeoffs should be pursued by future research.stover supply, biomass, soil productivity, soil organic carbon, nitrogen, Environmental Economics and Policy, Farm Management, Land Economics/Use, Resource /Energy Economics and Policy, C61, Q12, Q24, Q42, Q53,
A Corn Stover Supply Logistics System
No full textPublished in Applied Engineering in Agriculture, Vol. 26(3): 455‐461, 2010. American Society of Agricultural and Biological EngineersCorn stover, Economics, GHG emission, Logistics, Roll press compaction, Tub grinding, Agribusiness, Crop Production/Industries,
The Viability of Harvesting Corn Cobs and Stover for Biofuel Production in North Dakota
No full textThis study examines the impact of stochastic harvest field time, corn cob and stover harvest technologies, increases in farm size, and alternative tillage practices on profit maximizing potential of corn cob and stover collection in North Dakota. Using three mathematical programming models, we analyze farmers’ harvest activities under 1) corn grain only harvest option, 2) simultaneous corn grain and cob harvest(one-pass) option 3) separate corn grain and stover harvest (two-pass) option. Under the first corn grain only option, farmers are able to complete harvesting corn grain and achieve maximum net income in a fairly short amount of time with existing combine technology. However, under the simultaneous corn grain and cob one-pass harvest option, our findings indicate that farmers generate lower net income as compared to the net income of corn grain only harvest option. This is due to the slowdown in combine harvest capacity as a consequence of attaching cob harvester to the back of combine. Under the third option of a two-pass harvest system, time allocation is the main challenge and our evidence shows that with limited harvest field time available, farmers find it optimal to allocate most of their time harvesting grain, and then proceed to bale stover if time permits at the end of harvest season. As farm size increases, farmers are especially challenged in finding time to harvest both corn grain and cobs/stover. We show that a small decrease in corn yield due to changes in tillage practice can result in a large decline in the net profit of harvesting corn grain and cobs/stover.Cob, Stover, harvest field time, optimization, farm size, tillage, Crop Production/Industries, Production Economics,
Ethanol from Biomass: Economic and Environmental Potential of Converting Corn Stover and Hardwood Forest Residue in Minnesota
No full textResearch was undertaken to determine the economic feasibility and environmental impact of harvesting corn stover and hardwood forest residue in Minnesota and surrounding states for conversion to fuel ethanol at facilities located in Minnesota. It was estimated that only 7 of the total 41 million dry tons of corn stover produced and 3 of the 6.5 million dry tons of hardwood residue produced in the study region would likely be harvested each year. From these quantities, it would be physically feasible to produce about 874 million gallons of ethanol annually. It was estimated that 200 million gallons could be harvested at a delivered feedstock cost below 0.16 per-gallon higher than the upper-bound cost for corn-grain ethanol. Furthermore, this work indicates that large-scale substitution of petroleum gasoline with biomass-derived ethanol would have huge impacts with respect to reducing greenhouse gas emissions, although SOx emissions would increase.Resource /Energy Economics and Policy,
Kinetics of methane production and hydrolysis in anaerobic digestion of corn stover
No full textIn order to develop a time-saving method for determination of ultimate methane production, obtain the hydrolysis kinetic constant, and identify a determination method for the nonbiodegradable organic fraction of substrate (VSNB) of green and air-dried corn stover, the kinetics of methane production and hydrolysis were studied using batch tests. The results showed that the conventional first-order hydrolysis kinetic model was not suitable for describing the entire hydrolysis process of corn stover, because there were two first-order decay periods for hydrolysis of corn stover. The hydrolysis kinetic constants k(H,1) and kH,2 of the first and second periods were 0.1701 and 0.04151/d for green stover and 0.1052 and 0.03601/d for air-dried stover. The value of VSNB could be obtained by the graphical method rather than by the hydrolysis kinetic model. The obtained VSNB contents were 12.9% and 24.7% of VS (volatile solid) for green and air-dried stover, respectively. The ultimate methane production and corresponding digestion time could be understood through the methane production kinetic model by digestion experiments within a short time. The ultimate methane productions were 347.1 and 319.4 mL/g based on VS and the corresponding digestion times were 69.2 and 1823 days for green and air-dried stover, respectively. (C) 2016 Elsevier Ltd. All rights reserved
Economics of Sourcing Cellulosic Feedstock for Energy Production
No full textThis study investigates the economics of supplying wheat straw and corn stover within 100 mile radius of a potential new biorefinery in southeast North Dakota. In particular, straw and stover total delivery costs, potential straw and stover supply sites and least cost transportation routes are identified using a linear programming transport model and a GIS (Geographic Information Systems) mapping system. We show that USDA/NRCS (Natural Resources Conservation Service) future crop residue removal rate policies will be important for determining whether it is economically viable to harvest crop residues as potential feedstock for energy generation. Increase in residue removal rates narrow the size of residue supply areas and consequently result in lowering total transportation costs. There is an economic tradeoff between residue collection density and distance from the biorefinery. Most wheat residues are highly concentrated in the north, some distance from the biorefinery. Relying solely on wheat straw for supply needs require longer transportation distances which increases total cost. Using a combination of wheat and corn residues lowers total transportation costs. Since most wheat/corn residues are densely concentrated in north/south, regional highways would likely be the routes used often to transport the residues, as compared to interstate highways. Increased traffic volumes due to the hauling of crop residues would require additional investment in improving road conditions.Wheat Straw, Corn Stover, Density, Transportation Cost, GIS, Community/Rural/Urban Development, Crop Production/Industries,
D. B. Stover
No full textCaptain D. B. Stover was serving at Fort Douglas during the era of General Patrick Edward Connor
Using Real Options to Evaluate Investments in Ethanol Facilities
No full textThis paper uses real option analysis to evaluate investment decisions in ethanol facilities. First, we consider the option to expand the scale of a conventional ethanol plant. Second, we evaluate the option to choose a production technology given three drymilling choices – a conventional natural gas-fueled plant, a stover-fueled plant, and a stover-plus-syrup-fueled plant. We develop input-output coefficients and annual cash flow projections for a hypothetical small ethanol plant (50 million gallon capacity) using available industry and market price data. Scenario analysis is done to evaluate the effect of profitability and volatility on the option to expand. We find that the best decision during 2001-07 is often to expand, since the net present values of the investment project are positive. However, there are states in the binomial tree where it is best to wait. In relatively few such states the expansion project is simply rejected. During the early part of the period low profitability and high volatility more frequently favor strategies of waiting to invest until prices and profitability improve. During the latter part of the period (2005-07), profitability is sharply higher and most often the best strategy is to invest in the expansion. This result is consistent with the observed rapid increase in industry production capacity during 2005- 07. However, more recent market developments, sharply higher corn and natural gas prices and slightly higher ethanol prices during late 2007-early 2008, have combined to sharply reduce expected plant cash flow and profitability and cash flow volatility. The implication is that plant investment plans in 2008 would be increasingly placed on hold, which the real option model correctly predicts. The real option analysis of technology choice indicates that the stover-fueled technologies are most often chosen when compared to a natural gas-fueled conventional technology based on the prices that existed during 2001-2007.Financial Economics, Resource /Energy Economics and Policy,
Effects of ammonia fiber expansion (AFEX) treated corn stover on anaerobic microbes and corresponding digestion performance
No full textDynamic changes in microbial communities and digestion performance of AFEX treated corn stover co-digestion were compared to untreated corn stover co-digestion. Even though it took longer to stabilize the AFEX treated corn stover co-digestion system than it did for the untreated corn stover co-digestion, the results show that AFEX treated corn stover is a good feedstock to enhance the archaea community and improve biogas production. In the stabilized digestion system, the AFEX treated corn stover co-digestion increased abundance of archaea community (11.8%) by approximately three times compared to the untreated corn stover co-digestion (4.3%), The corresponding biogas production (213 L/kg VS loading) of the AFEX treated corn stover co-digestion was 22% higher than that (175 L/kg VS loading) of the untreated corn stover co-digestion. AFEX treatment could enable more extensive use of lignocellulosic biomass for anaerobic digestion to generate biogas and thereby provide another route for lignocellulosic biofuel production
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