Dairy cow longevity: Impact of animal health and farmers' investment decisions

A dairy farmer's decision to cull or keep dairy cows is likely a complex decision based on animal health and farm management practices. The present paper investigated the relationship between cow longevity and animal health, and between longevity and farm investments, while controlling for farm-specific characteristics and animal management practices, by using Swedish dairy farm and production data for the period 2009 to 2018. We used the ordinary least square and unconditional quantile regression model to perform mean-based and heterogeneous-based analysis, respectively. Findings from the study indicate that, on average, animal health has a negative but insignificant effect on dairy herd longevity. This implies that culling is predominantly done for other reasons than poor health status. Investment in farm infrastructure has a positive and significant effect on dairy herd longevity. The investment in farm infrastructure creates room for new or superior recruitment heifers without the need to cull existing dairy cows. Production variables that prolong dairy cow longevity include higher milk yield and an extended calving interval. Findings from this study imply that the relatively short longevity of dairy cows in Sweden compared with some dairy producing countries is not a result of problems with health and welfare. Rather, dairy cow longevity in Sweden hinges on the farmers' investment decisions, farm-specific characteristics and animal management practices.     

Considering milk price volatility for investment decisions on the farm level after European milk quota abolition

After the abolition of the milk quota in the European Union, milk price volatility is expected to increase because of the liberalized market conditions. At the same time, investment appraisal methods have not been updated to capture the increased uncertainty. Therefore, the objective of this paper is to assess the effect of changing price volatility due to quota abolition on investment decisions at the dairy farm level. To contribute to the objective and to approximate milk price volatility after the European milk quota abolition, the risk-adjusted discount rate for risk-averse dairy farmers is derived based on the milk price volatility of a milk price series from New Zealand. New Zealand dairy farmers have faced liberalized market conditions for more than 3 decades. Afterward, the risk-adjusted discount rate is applied to appraise milking technology investments for an average German dairy farmer. The results show that it is still more reasonable to invest in a parlor system than an automated milking system, although the net present value of the parlor system investment varies between €191,723 for risk-neutral dairy farmers and €100,094 for modestly risk-averse dairy farmers. For the automated milking system investment, the same calculations lead to €132,702 for risk-neutral dairy farmers and €31,635 for risk-averse dairy farmers. According to higher levels of milk price volatility after milk quota abolition, the reduction of the expected utility of the underlying investment decision for modest risk-averse dairy farmers is almost similar to a milk price decrease of 5% for risk-neutral dairy farmers. Therefore, the findings urge finance providers and extension services to consider the change of increasing milk price volatility after dairy quota abolition when giving dairy farmers financial advice. The risk-adjusted discount rate is a flexible tool to do so.     

Importance of unburned coal carbon, black carbon, and amorphous organic carbon to phenanthrene sorption in sediments

The aim of this paper was to estimate the contribution to total phenanthrene sorption from unburned coal and black carbon (BC; soot and charcoal) in sediment. We determined sorption isotherms for five Argonne Premium Coal standards over a wide concentration interval (0.01-10 000 ng/L). The coals showed strong and nonlinear sorption (carbon-normalized K(F) = 5.41-5.96; nF = 0.68-0.82). Coal sorption appeared to become more nonlinear with increasing coal maturity. The coal's specific surface area appeared to influence K(F). On the basis of the current coal sorption observations combined with earlier petrographic analyses and BC sorption experiments, we calculated for one particular sediment that coal, BC, and "other" OC were all important to PHE sorption in the environmentally relevant nanogram per liter range. This indicates that it is important to consider strong sorption to coal in the risk assessment of coal-impacted geosorbents (e.g., river beds) where coal is mined/shipped and manufactured gas plant sites.     

Storing syngas lowers the carbon price for profitable coal gasification

Integrated gasification combined cycle (IGCC) electric power generation systems with carbon capture and sequestration have desirable environmental qualities but are not profitable when the carbon dioxide price is less than approximately $50 per metric ton. We examine whether an IGCC facility that operates its gasifier continuously butstores the syngas and produces electricity only when daily prices are high may be profitable at significantly lower CO2 prices. Using a probabilistic analysis, we have calculated the plant-level return on investment (ROI) and the value of syngas storage for IGCC facilities located in the U.S. Midwest using a range of storage configurations. Adding a second turbine to use the stored syngas to generate electricity at peak hours and implementing 12 h of above-ground high-pressure syngas storage significantly increases the ROI and net present value. Storage lowers the carbon price at which IGCC enters the U.S. generation mix by approximately 25%.     

Characteristics of particulate carbon emissions from real-world Chinese coal combustion

Particulate matter emissions from a series of different Chinese coal combustion systems were collected and analyzed for elemental and organic carbon (EC, OC), and molecular markers. Emissions from both industrial boilers and residential stoves were investigated. The coal used in this study included anthracite, bituminite, and brown coal, as well as commonly used coal briquettes produced in China for residential coal combustion. Results show significant differences in the contribution of carbonaceous species to particulate mass emissions. Industrial boilers had much higher burn out of carbon yielding particulate matter emissions with much lower levels of OC, EC, and speciated organic compounds, while residential stoves had significantly higher emissions of carbonaceous particulate matter with emission rates of approximately 100 times higher than that of industrial boilers. Quantified organic compounds emitted from industrial boilers were dominated by oxygenated compounds, of which 46-68% were organic acids, whereas the dominate species quantified in the emissions from residential stoves were PAHs (38%) and n-alkanes (20%). An important observation was the fact that emission factors of PAHs and the distribution of hopanoids were different among the emissions from industrial and residential coal combustion even using the same coal for combustion. Although particulate matter emissions from industrial and residential combustion were different in many regards, picene was detected in all samples with detectable OC mass concentrations, which supports the use of this organic tracer for OC from all types of coal combustion. 17alpha(H),21beta(H)-29-norhopane was the predominant hopanoid in coal combustion emissions, which is different from mobile source emissions and may be used to distinguish emissions from these different fossil fuel sources.     

巨资重压下的林纸一体化工程建设

近年来林纸一体化工程建设规模渐趋巨大,资金需求渐趋庞大,融资压力渐趋沉重,资金供需矛盾十分突出.本文阐述了巨资重压下对林纸一体化工程建设的影响及融资建议.     

Greening coal: breakthroughs and challenges in carbon capture and storage

Like it or not, coal is here to stay, for the next few decades at least. Continued use of coal in this age of growing greenhouse gas controls will require removing carbon dioxide from the coal waste stream. We already remove toxicants such as sulfur dioxide and mercury, and the removal of CO? is the next step in reducing the environmental impacts of using coal as an energy source (i.e., greening coal). This paper outlines some of the complexities encountered in capturing CO? from coal, transporting it large distances through pipelines, and storing it safely underground.     

“双碳”目标下中国居民食物消费结构升级及碳排放分析研究

目的 分析2014—2020年间中国居民食物消费结构及碳排放量,为倡导居民可持续消费模式,实现“双碳”目标提供科学支持。方法 以食物消费为对象,并进一步延伸至食物碳排放。综合运用食物碳排放系数和生命周期法,从直接和间接两个方面对我国居民食物消费引起的碳排放量进行全面的测算,探究食物碳排放演变趋势。结果 中国居民食物结构随动物性食物消费量逐年递增,温室气体排放量也有较大幅度增长。分别假设2030、2040、2050年逐渐调整其食物消费结构至膳食指南场景,温室气体排放总量分别在2030、2040、2049年达到峰值,温室气体排放量较现状水平均有一定幅度增加。结论 中国食物消费结构调整带来的碳减排压力较大,并结合上述结果结论,给出合理的政策启示。     

Enhanced coagulation for satisfying the arsenic maximum contaminant level under variable and uncertain conditions

This study evaluated the effects of influent variability and model parameter uncertainty when utilizing enhanced coagulation modification to bring existing treatment plants into compliance with a stricter arsenic regulation. Enhanced coagulation modification options include: (1) increased ferric chloride dose, (2) addition of an acid dose, and (3) a combination of the individual options. Arsenic removal is described by adsorption to hydrous ferric oxide with a surface complexation model and subsequent removal through sedimentation and filtration. The least-cost modification for reliably satisfying the arsenic regulation is determined using an optimization algorithm that explicitly includes variability and uncertainty. The ferric chloride only modification is always the least-cost treatment modification. The ferric chloride and acid modification could be the least-cost option when considering waste handling processes due to a tradeoff between modification cost and sludge production. By inclusion of variability and uncertainty, the relative importance of individual parameter distributions for determining whether the arsenic regulation is reliably satisfied is assessed. Influent arsenic concentration variability is always critical, while variability in the influent pH and sulfate concentrations and uncertainty in the filter removal efficiency and equilibrium adsorption constant for the triple bond Fe(s)OHCa2+ surface species are critical or important, depending on influent conditions.     

碳交易及消费补贴下的服装行业碳减排决策问题

在"双碳"目标下,全国碳交易市场悄然上线,为使服装企业更好地应对碳交易,建立由原料供应商、制造商、零售商和回收商组成的服装闭环供应链模型,着重探讨了政府对再制造服装消费者补贴及制造商碳减排投资对服装行业发展、供应链成员利润及供应链碳排放总量的影响等.研究发现:随着碳交易价格的上涨,若无减排及无补贴,服装企业难以长久维系...     

Ash particulate formation from pulverized coal under oxy-fuel combustion conditions

Aerosol particulates are generated by coal combustion. The amount and properties of aerosol particulates, specifically size distribution and composition, can be affected by combustion conditions. Understanding the formation of these particles is important for predicting emissions and understanding potential deposition. Oxy-fuel combustion conditions utilize an oxygen-enriched gas environment with CO(2). The high concentration of CO(2) is a result of recycle flue gas which is used to maintain temperature. A hypothesis is that high CO(2) concentration reduces the vaporization of refractory oxides from combustion. A high-temperature drop-tube furnace was used under different oxygen concentrations and CO(2) versus N(2) to study the effects of furnace temperature, coal type, and gas phase conditions on particulate formation. A scanning mobility particle sizer (SMPS) and aerodynamic particle sizer (APS) were utilized for particle size distributions ranging from 14.3 nm to 20 μm. In addition, particles were collected on a Berner low pressure impactor (BLPI) for elemental analysis using scanning electron microscopy and energy dispersive spectroscopy. Three particle size modes were seen: ultrafine (below 0.1 μm), fine (0.1 to 1.0 μm), and coarse (above 1 μm). Ultrafine mass concentrations were directly related to estimated particle temperature, increasing with increasing temperature. For high silicon and calcium coals, Utah Skyline and PRB, there was a secondary effect due to CO(2) and the hypothesized reaction. Illinois #6, a high sulfur coal, had the highest amount of ultrafine mass and most of the sulfur was concentrated in the ultrafine and fine modes. Fine and coarse mode mass concentrations did not show a temperature or CO(2) relationship. (The table of contents graphic and abstract graphic are adapted from ref 27.).     

Water use at pulverized coal power plants with postcombustion carbon capture and storage

Coal-fired power plants account for nearly 50% of U.S. electricity supply and about a third of U.S. emissions of CO(2), the major greenhouse gas (GHG) associated with global climate change. Thermal power plants also account for 39% of all freshwater withdrawals in the U.S. To reduce GHG emissions from coal-fired plants, postcombustion carbon capture and storage (CCS) systems are receiving considerable attention. Current commercial amine-based capture systems require water for cooling and other operations that add to power plant water requirements. This paper characterizes and quantifies water use at coal-burning power plants with and without CCS and investigates key parameters that influence water consumption. Analytical models are presented to quantify water use for major unit operations. Case study results show that, for power plants with conventional wet cooling towers, approximately 80% of total plant water withdrawals and 86% of plant water consumption is for cooling. The addition of an amine-based CCS system would approximately double the consumptive water use of the plant. Replacing wet towers with air-cooled condensers for dry cooling would reduce plant water use by about 80% (without CCS) to about 40% (with CCS). However, the cooling system capital cost would approximately triple, although costs are highly dependent on site-specific characteristics. The potential for water use reductions with CCS is explored via sensitivity analyses of plant efficiency and other key design parameters that affect water resource management for the electric power industry.     

气候变暖背景下的低碳可持续发展及碳足迹计算

发达国家自工业革命后的100余年中释放了大量温室气体使地球气候变暖,造成海平面上升,极端天气频现,危害人类生命安全.联合国为此多次召开气候大会,其中具有里程碑意义的有2次:(1)1997年气候会议签署《京都议定书》,确定6种温室气体,开启低碳可持续发展道路并建立碳足迹制度;(2)2015年气候会议中大部分国家签署《巴黎...     

Delaying investments in sensor technology: The rationality of dairy farmers' investment decisions illustrated within the framework of real options theory

The adoption rate of sensors on dairy farms varies widely. Whereas some sensors are hardly adopted, others are adopted by many farmers. A potential rational explanation for the difference in adoption may be the expected future technological progress in the sensor technology and expected future improved decision support possibilities. For some sensors not much progress can be expected because the technology has already made enormous progress in recent years, whereas for sensors that have only recently been introduced on the market, much progress can be expected. The adoption of sensors may thus be partly explained by uncertainty about the investment decision, in which uncertainty lays in the future performance of the sensors and uncertainty about whether improved informed decision support will become available. The overall aim was to offer a plausible example of why a sensor may not be adopted now. To explain this, the role of uncertainty about technological progress in the investment decision was illustrated for highly adopted sensors (automated estrus detection) and hardly adopted sensors (automated body condition score). This theoretical illustration uses the real options theory, which accounts for the role of uncertainty in the timing of investment decisions. A discrete event model, simulating a farm of 100 dairy cows, was developed to estimate the net present value (NPV) of investing now and investing in 5 yr in both sensor systems. The results show that investing now in automated estrus detection resulted in a higher NPV than investing 5 yr from now, whereas for the automated body condition score postponing the investment resulted in a higher NPV compared with investing now. These results are in line with the observation that farmers postpone investments in sensors. Also, the current high adoption of automated estrus detection sensors can be explained because the NPV of investing now is higher than the NPV of investing in 5 yr. The results confirm that uncertainty about future sensor performance and uncertainty about whether improved decision support will become available play a role in investment decisions.     

CO2 adsorption on carbon models of organic constituents of gas shale and coal

Imperfections of the organic matrix in coal and gas shales are modeled using defective and defect-free graphene surfaces to represent the structural heterogeneity and related chemical nature of these complex systems. Based upon previous experimental investigations that have validated the stability and existence of defect sites in graphene, plane-wave electronic density functional theory (DFT) calculations have been performed to investigate the mechanisms of CO(2) adsorption. The interactions of CO(2) with different surfaces have been compared, and the physisorption energy of CO(2) on the defective graphene adsorption site with one carbon atom missing (monovacancy) is approximately 4 times as strong as that on a perfect defect-free graphene surface, specifically, with a physisorption energy of ～210 meV on the monovacancy site compared to ～50 meV on a perfect graphene surface. The energy associated with the chemisorption of CO(2) on the monovacancy site is substantially stronger at ～1.72 eV. Bader charge, density of states, and vibrational frequency estimations were also carried out and the results indicate that the CO(2) molecule binds to the surface becoming more stable upon physisorption onto the monovacancy site followed by the original C═O bonds weakening upon CO(2) chemisorption onto the vacancy site.     

粉煤灰替代草炭作基质的烤烟漂浮育苗效果

以粉煤灰为主要原料完全替代烟草漂浮育苗基质配方中的草炭,再添加不同比例珍珠岩作为主处理,以草炭为基质主要原料作为对照,进行常规漂浮育苗和大棚育苗试验.结果表明:用粉煤灰完全替代草炭作为育苗基质的处理,其出苗率、成苗率、壮苗率,都与以草炭为基质主要材料的对照没有显著差异,粉煤灰可以作为烤烟漂浮育苗基质草炭的替代材料.5%珍珠岩和95%粉煤灰是粉煤灰基质配方组合的最佳使用比例.     

Minimization of water consumption under uncertainty for a pulverized coal power plant

Coal-fired power plants are large water consumers. Water consumption in thermoelectric generation is strongly associated with evaporation losses and makeup streams on cooling and contaminant removal systems. Thus, minimization of water consumption requires optimal operating conditions and parameters, while fulfilling the environmental constraints. Several uncertainties affect the operation of the plants, and this work studies those associated with weather. Air conditions (temperature and humidity) were included as uncertain factors for pulverized coal (PC) power plants. Optimization under uncertainty for these large-scale complex processes with black-box models cannot be solved with conventional stochastic programming algorithms because of the large computational expense. Employment of the novel better optimization of nonlinear uncertain systems (BONUS) algorithm, dramatically decreased the computational requirements of the stochastic optimization. Operating conditions including reactor temperatures and pressures; reactant ratios and conditions; and steam flow rates and conditions were calculated to obtain the minimum water consumption under the above-mentioned uncertainties. Reductions of up to 6.3% in water consumption were obtained for the fall season when process variables were set to optimal values. Additionally, the proposed methodology allowed the analysis of other performance parameters like gas emissions and cycle efficiency which were also improved.     

The storage life of chicken carcasses packaged under carbon dioxide

Broiler chicken carcasses were packaged under vacuum in film of low oxygen transmission rate, or under CO2 in gas-impermeable aluminum foil laminate. The packaged carcasses were stored at +3 or -1.5 degrees C. The initial flora was dominated by enterobacteria. Vacuum-packaged carcasses developed microbial populations in which enterobacteria continued to predominate, and were spoiled by persistent putrid odours after 2 weeks storage at 3 degrees C or 3 weeks storage at -1.5 degrees C. Growth of enterobacteria was inhibited on carcasses packaged under CO2, the microflora that developed being dominated by lactobacilli. However, slow growth of the enterobacteria eventually resumed, and putrid spoilage was apparent after 7 weeks storage at 3 degrees C or 14 weeks storage at -1.5 degrees C.     

Mathematical modeling of Escherichia coli inactivation under high-pressure carbon dioxide

Inactivation curves of Escherichia coli under high carbon dioxide pressures (2.5, 5.1, 7.6 and 10.1 MPa) at different temperatures (20, 30, 40 and 45 degrees C) were analyzed using the modified Gompertz model. The phase disappearance (time for complete inactivation of all cells, lambda) and the inactivation rate (mu) of E. coli were inversely related. Inactivation rates (mu) of E. coli were higher at 45 degrees C under 10.1 MPa CO2 pressure than at 25, 30 and 40 degrees C under 2.5, 5.1 and 7.6 MPa CO2 pressure. Increased pressure and temperature had significant effects on the survival of E. coli. The temperature dependence of the inactivation rate constant was analyzed based on the Arrhenius, linear and square-root models. The temperature sensitivity (high E(mu)) determined based on the Arrhenius model was higher at high temperatures. E(mu) (activation energy) value was -186.56 Kjoule/mol at 10.1 Mpa, and -137.24, -167.25 and -183.80 Kjoule/mol at 2.5, 5.1 and 7.6 MPa, respectively. Results of this study enable the prediction of microbial inactivation exposed to different CO2 pressures and temperatures.