Market Penetration of Biomass Fuels for Electricity Generation

The electric power sector is a main source of carbon dioxide (CO2) emissions that contribute to global warming. In the U.S., fossil fuel fired power plants are responsible for about 38% of the total CO2 emissions from all sources. Switching a significant portion of the U.S. electricity generating capacity from fossil fuels to biomass fuels would help reduce CO2 emissions from the electric power industries. At present, biomass accounts for only about 1% of the fuel used for electricity generation in the U.S. In contrast, coal alone accounts for about 50%, and nuclear, natural gas and petroleum explain for about 20%, 16% and 3% respectively of the fuels used for electricity generation. There are a number of factors that may influence the extent to which biomass fuels are to penetrate the electricity market: facility needs, growth in electricity demand, prices of fossil fuels and advances in technology. Electricity is generally produced in large, expensive and long-lived facilities. However new facilities or capitals are often built to meet demand growth. Capitals can be generally said to have a given productive lifetime. As new capital investment occurs and older capital is retired, electricity producers will have opportunities to substitute away from fossil fuels. Thus, an increase in the market penetration of biomass power will likely occur when existing fossil power plants are retired and replaced by new and less carbon intensive power plants. The market penetration of biomass electricity will also depend on a strong growth in electricity demand due to economic and population growth, availability and prices of fuels, environmental considerations and technological advances. Specifically, this paper will look at the potential for biomass penetration into the electricity market considering: a) prices of fossil fuels such as coal, natural gas and petroleum for power production, b) the capital turnover rate for existing stock of fossil power plants, c) changes in technologies which could facilitate the use of biomass as fuels for electricity generation.Resource /Energy Economics and Policy,

Economics of Biomass Fuels for Electricity Production: A Case Study with Crop Residues

In the past, studies on agricultural feedstocks for energy production were motivated by rising fossil fuel prices interpreted by many as caused by resource depletion. However, today's studies are mainly motivated by concerns for climate change and global warming. Currently, most studies concentrate on liquid fuels with little study devoted toward electricity. This study examines crop residues for electricity production in the context of climate change and global warming. We use sector modeling to simulate future market penetration for biopower production from crop residues. Our findings suggest that crop residues cost much more than coal because they have lower heat content and higher production/hauling costs. For crop residues to have any role in electricity generation either the carbon or carbon dioxide equivalent greenhouse gas price must rise to about 15 dollars per ton or the price of coal has to increase to about 43 dollars per ton. We find crop residues with higher heat content and lower production costs such as wheat residues have greater opportunities in biopower production than the residues with lower heat content and higher production costs. In addition, the analysis shows that improvements in crop yield do not have much impact on biopower production. However, the energy recovery efficiency does have significant positive impact but only if the carbon equivalent price rises substantially. The analysis also indicates the desirability of cofiring biomass as opposed to 100% replacement because this reduces hauling costs and increases the efficiency of heat recovery. In terms of policy implications, imposing carbon emission pricing could be an important step in inducing electric power producers to include agricultural biomass in their fuel-mix power generation portfolios and achieve greenhouse gas emission reductions.Resource /Energy Economics and Policy,

The Viability of Harvesting Corn Cobs and Stover for Biofuel Production in North Dakota

This 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,

Determination of regional bone blood flow by means of fluorescent microspheres using an automated sample-processing procedure

The determination of regional blood flow utilizing fluorescent microspheres (FMs) is an established method for numerous organs. Recent progress, in particular the automation of sample processing, has further improved this method. However, the FM method (reference sample technique), which allows repetitive measurement of regional organ blood flow, has so far not been used for the determination of blood flow in bone. The aim of the present study was to establish FM for the quantification of regional bone blood flow (RBBF). Female, anesthetized New Zealand rabbits (n = 6) received left ventricular injections of different amounts of FM at six subsequent time points. In order to examine the precision of RBBF determination, two different FM species were injected simultaneously at the sixth injection. At the end of the experiments the femoral and tibial condyles of each hind limb were removed and the fluorescence intensity in the tissue samples was measured by an automated procedure. In an in vitro study we have shown that acid digestion of the crystalline matrix has no effect on the fluorescence characteristics of FM. The determination of the number of spheres per tissue sample revealed that depending on the tissue sample size up to 3 x 10(6) spheres/injection were necessary to obtain about 400 microspheres in the individual bone samples. RBBF values of the tibial and femoral condyles did not differ at various injection intervals. The tibial blood flow values varied between 6.6 +/- 1.1 and 8.5 +/- 1.4 ml/min/100 g and were significantly higher than those of the femur (4.3 +/- 1.1 to 6.0 +/- 1.8 ml/min/100 g). The bone blood flow values obtained by simultaneous injection of two FM species correlated significantly (r = 0.96, slope = 1.06, intercept = 0.05), the mean difference was 0.39 +/- 1.11 ml/min/100 g. Our data demonstrate that the measurement of RBBF by means of FM allows a valid determination of RBBF. Copyright (C) 2003 S. Karger AG, Basel

The Bold Priest of Bordeaux

Story of Father Chaminad

Transition from subbarrier to deep subbarrier regimes in heavy-ion fusion reactions

We analyze the recent experimental data of heavy-ion fusion cross sections available up to deep subbarrier energies in order to discuss the threshold incident energy for a deep subbarrier fusion hindrance phenomenon. To this end, we employ a one-dimensional potential model with a Woods-Saxon internuclear potential. Fitting the experimental data in two different energy regions with different Woods-Saxon potentials, we define the threshold energy as an intersect of the two fusion excitation functions. We show that the threshold energies so extracted are in good agreement with the empirical systematics as well as with the values of the Krappe-Nix-Sierk (KNS) potential at the touching point. We also discuss the asymptotic energy shift of fusion cross sections with respect to the potential model calculations, and show that it decreases with decreasing energies in the deep subbarrier region although it takes a constant value at subbarrier energies.Comment: 4 pages, 4 figure

Comparison of regional blood flow values measured by radioactive and fluorescent microspheres

Fluorescent microspheres (FM) have become an attractive alternative to radioactive microspheres (RM) for the measurement of regional blood flow (RBF). The aim of the present study was to investigate the comparability of both methods by measuring RBF with FM and RM. Eight anaesthetised pigs received simultaneous, left atrial injections of FM and RM with a diameter of 15 mum at six different time points. Blood reference samples were collected from the descending aorta. RBF was determined in tissue samples of the myocardium, spleen and kidneys of all 8 animals. After radioactivity of the tissue samples was determined, the samples were processed automatically for measuring fluorescence using a recently developed filter device (SPU). RBF was calculated with both the isotope and spectrometric data of both methods for each sample resulting in a total of 10,512 blood flow values. The comparison of the RBF values yielded high linear correlation (mean r(2) = 0.95 +/- 0.03 to 0.97 +/- 0.02) and excellent agreement (bias 5.4-6.7%, precision 9.9-16.5%) of both methods. Our results indicate the validity of MS and of the automated tissue processing technique by means of the SPU. Copyright (C) 2002 S. Karger AG, Basel

Economics of Sourcing Cellulosic Feedstock for Energy Production

This 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,