Frameworks for comparing emissions associated with production, consumption, and international trade

While the problem of climate change is being perceived as increasingly urgent, decision-makers struggle to agree on the distribution of responsibility across countries. In particular, representatives from countries hosting emissions-intensive exporting industries have argued that the importers of emissions-intensive goods should bear the responsibility, and ensuing penalties. Indeed, international trade and carbon leakage appear to play an increasingly important role in the carbon emissions debate. However, definitions of quantities describing the embodiment of carbon emissions in internationally traded products, and their measurement, have to be sufficiently robust before being able to underpin global policy. In this paper we critically examine a number of emissions accounting concepts, examine whether the ensuing carbon balances are compatible with monetary trade balances, discuss their different interpretations, and highlight implications for policy. In particular, we compare the emissions embodied in bilateral trade (EEBT) method which considers total trade flows with domestic emission intensities, with the multi-regional input-output (MRIO) method which considers trade only into final consumption with global emission intensities. If consumption-based emissions of different countries were to be compared, we would suggest an MRIO approach because of the global emissions coverage inherent in this method. If trade-adjusted emission inventories were to be compared, we would suggest an EEBT approach due to the consistency with a monetary trade balance.     

Energy balance of dairy cattle in relation to milk production variables and fertility

Variables derived from milk yield records were investigated to find an easy to measure and readily available indicator of the energy balance status of a lactating cow. Weekly energy balances during the first 180 d in milk (DIM) were calculated from weekly yield, live weight, and energy intake records for 470 first lactation heifers. The energy balance curve for each cow was estimated using a random regression model. From each curve, three measures were calculated to describe the energy balance status: 1) total energy deficit in early lactation, 2) interval for return to positive energy balance, and 3) lowest value (nadir) for energy balance. Mean energy deficit per lactation was 776.8 MJ of NE(L)/d, interval for return to positive energy balance was 41.47 d, and nadir was -33.72 MJ of NE(L)/d. Regression analysis to relate these variables to interval to start of luteal activity (measured using progesterone profiles) showed that a low nadir of energy balance was related to delayed resumption of luteal activity. In general, a 10 MJ of NE(L)/d lower nadir of energy balance corresponded to a delay of ovulation of 1.25 d. A relatively strong decrease in fat percentage during early lactation was significantly correlated with lower nadir of energy balance, larger energy deficit, and later return to positive energy balance. The maximal correlation was between nadir of energy balance and a decrease of milk fat percentage. This correlation remained above 0.60 throughout the first 26 DIM but dropped to 0.14 at 180 DIM. Large decreases in milk fat percentage were related to high initial fat percentages at the start of lactation and slightly lower fat percentages later during lactation. Hence, we concluded that a decrease in fat percentage during early lactation might serve as an indicator of energy balance.     

Solvent-extractable polycyclic aromatic hydrocarbons in biochar: influence of pyrolysis temperature and feedstock

Despite the increasing agricultural use of biochar as a way of combining the utilization of biomass for energy production with the removal of CO(2) from the atmosphere, it is not known how variations in pyrolysis temperature and feedstock type affect concentration and composition of polycyclic aromatic hydrocarbons (PAHs) that inevitably form and associate with biochar. To close this knowledge gap, we quantified 11 unsubstituted three- to five-ring PAHs as well as alkylated forms of phenanthrene and anthracene in grass and wood chars produced in 100 °C increments across a temperature range (100 to 700 °C). Our results show that solvent-extractable PAH concentrations in biochars produced at heat treatment temperatures (HTTs) of 400 and 500 °C greatly exceed those observed at higher and lower temperature, supporting a low HTT solid-phase formation mechanism operable at temperatures commonly used for industrial biochar production. The maximum extractable yield of 'pyrolytic' unsubstituted PAHs for grass (22 μg g(-1) at HTT = 500 °C) greatly exceeds the value for wood (5.9 μg g(-1)). Moreover, PAH signatures (e.g., total monomethylphenanthrene to phenanthrene ratios, MP/P ～2-3) at intermediate temperatures (400 °C) resemble those of fossil oils rather than that commonly attributed to pyrolytic products. Further research is needed to characterize the PAH evolution in modern pyrolysis reactors and assess the fate of biochar-bound PAHs in soils and sediments. Various commonly applied PAH ratios and indicator compounds show promise as markers for specific feedstock materials and pyrolysis conditions of biochars in environmental systems.     

Stochastic state‐space temperature regulation of biochar production. Part II: Application to manure processing via pyrolysis

BACKGROUND: State‐of‐the‐art control systems that can guarantee the pyrolytic exposure temperature are needed in the production of designer biochars. These designer biochars will have tailored characteristics that can offer improvement of specific soil properties such as water‐holding capacity and cation exchange capacity. RESULTS: A novel stochastic state‐space temperature regulator was developed for the batch production of biochar that accurately matched the pyrolytic exposure temperature to a defined temperature input schedule. This system was evaluated by processing triplicate swine manure biochars at two temperatures, 350 and 700 °C. The results revealed a low coefficient of variation (CV) in their composition and near‐similar ¹³C nuclear magnetic resonance structure as well as thermal degradation patterns. When pyrolysing at 350 °C, the stochastic state‐space regulator generated a biochar with lower CV in ultimate (i.e. CHNS) compositional analysis than the original feedstock. CONCLUSION: This state‐space controller had the ability to pyrolyse a feedstock and generate a consistent biochar with similar structural properties and consistent compositional characteristics. Published 2011 by John Wiley & Sons, Ltd.     

Energy balance and diurnal variation in methane production as affected by feeding frequency in Jersey cows in late lactation

Methane (CH₄) production of ruminants typically increases with increased dry matter intake (DMI). However, few studies have observed the effects of feeding multiple times a day and its effects on diurnal variation in CH₄ production and energy balance in late-lactation dairy cattle. A study using headbox-style indirect calorimetry and 12 multiparous (225 ± 16.2 d in milk; mean ± SD) lactating Jersey cows was conducted to determine the effects of feeding twice daily on diurnal variation in CH₄ production and total energy balance. A crossover design with 14-d periods (10 d of adaption and 4 d of collection) was used to compare 2 treatments. Treatments consisted of either once a day feeding (1×; 100% of feed given at 1000 h) or twice a day feeding (2×; 50% of feed given at 1000 h and the final 50% at 2000 h) with a common diet fed in both treatments. Dry matter intake was not different between treatments, with a mean of 16.9 ± 0.88 kg/d. Once a day feeding tended to have greater milk yield compared with twice a day feeding (21.2 vs. 20.4 ± 1.59 kg/d, respectively). Milk fat and milk protein percentage were not different, with means of 6.18 ± 0.20% and 3.98 ± 0.08%, respectively. Total CH₄ production did not differ between treatments, with a mean of 402.1 ± 20.8 L/d. Similarly, CH₄ per unit of milk yield and DMI was not different between treatments, with means of 20.5 ± 1.81 and 23.8 ± 1.21 L/kg, respectively. Feeding frequency did not affect diurnal variation of hourly CH₄ production, with a mean of 17.1 ± 0.74 L/h. A trend was observed for a treatment × hour interaction. Methane production per hour increased after the second feeding for cattle fed twice versus once daily. Gross energy, digestible energy, metabolizable energy, and balance (milk plus tissue) per kilogram of DMI did not differ by feeding frequency, with means of 4.41 ± 0.01, 3.05 ± 0.03, 2.63 ± 0.03, and 1.32 ± 0.08 Mcal/kg of DM, respectively. Metabolizable energy for maintenance was 146 kcal/kg of metabolic body weight, with an efficiency of converting metabolizable energy to net energy balance (milk plus tissue) of 76%. Nitrogen balance did not differ among treatments, with a mean balance of 17.3 ± 13.0 g/d. Therefore, total CH₄ production and energy maintenance were not affected by feeding frequency. However, CH₄ was variable throughout the day, and caution should be exercised when collecting CH₄ samples at a limited number of time points because this may under- or overestimate total production.     

Energy balance and reproduction on dairy cows fed to achieve low or high milk production on a pasture-based system

This study investigated the energy balance, metabolic changes, reproduction, and health in Australian Holstein-Friesian cows of average genetic merit fed to produce 6,000 L of milk/cow per lactation (restricted production; Rp) on a predominantly grazed pasture diet, or 9,000 L of milk/cow per lactation (high production: Hp) on a more intensive feeding regimen by using a partial mixed ration to supplement pasture. The mean 4% fat-corrected milk (FCM) and standard deviation achieved was 8,466 ± 1,162 L/cow per lactation for the Hp herd and 6,748 ± 787 L/cow per lactation for the Rp herd. During early lactation, the degree of estimated negative energy balance was less in the Hp cows than in the Rp cows (−16.1 vs. −29.1 MJ/cow per day, respectively). Consequently, the mobilization of body reserves was also lower in the Hp cows, and this was reflected in lower concentrations of nonesterified fatty acids (0.70 vs. 0.84 mmol/L) and β-hydroxybutyrate (0.51 vs. 0.69 mmol/L) and greater concentrations of glucose (3.51 vs. 3.34 mmol/L) and insulin-like growth factor-I (78.9 vs. 58.7 ng/mL) for Hp and Rp cows, respectively. After calving, body condition score and body weight decreased to a similar extent in both herds and did not reflect the differences in mobilization of body reserves between the 2 herds. Reproductive performance was not significantly related to level of milk yield. The mean interval from calving to first active corpus luteum was 33 (SD = 20) d postpartum, and there were 1.4 (SD = 0.8) estrus cycles before the beginning of the breeding period (>50 d postpartum). The interval from calving to pregnancy was 114 d, and the pregnancy rate after 12 wk of mating was 74%. The number of cows with ovarian abnormalities was also similar between the 2 herds. Cows with a long postpartum anestrus had the lowest concentration of insulin-like growth factor-I. The number of health-related disorders was also similar between the herds, with the exception of mastitis, for which the incidence was significantly greater in the Hp cows. The results indicate that the production per cow could be increased from 6,748 L of FCM/cow per lactation for cows grazing pasture and supplemented with concentrates only at milking to 8,466 L of FCM/cow per lactation, in one lactation, by supplementing pasture with a partial mixed ration. Despite the fact that production per cow increased substantially, the degree of estimated negative energy balance and the metabolic changes in early lactation were lower and reproductive performance was maintained.     

Toxicological issues associated with production and processing of meat

Meat is a very complex and continuously changing ex vivo system of various high- and low-molecular substances that can be used for satisfying needs of the human organism for metabolic energy, building material and fulfilling of the other vital functions. A great majority of these substances are useful and safe for the consumer. Yet, meat and meat products may always contain substances exerting detrimental effects to the consumer's organism. The present paper is a literature review of the most important potentially toxic substances found in meat and meat products; their classification, ways of getting into the meat or formation during meat processing, undesirable physiological outcomes and biochemical mechanisms of their toxic effects, and methods for reduction of these responses.     

生物质快速热解生物油产率和组分的影响因素

生物质快速热解是能源转化中效率较高的一种。本文从物料特性(物料组成、粒径、含水率)和反应条件(升温速率、反应温度、滞留时间、压力和催化剂)两方面对影响生物油产率和组分进行论述,分析了影响生物油组分的主要因素:物料组成、反应温度和催化剂,对影响生物油产率的主要因素物料粒径、温度和气体停留时间进行阐述。     

Energy balance and lactation response in Holstein cows supplemented with cottonseed with or without calcium soap.

Holstein cows (n = 58, 21 primiparous), fed corn and wilted grass silages (63:37, DM basis) for free choice consumption, were assigned to control concentrate or supplemented concentrate during wk 1 to 16 postpartum with linted whole cottonseed (15% of projected DMI) alone or with Megalac (.54 kg/d). Our objective was to examine the effects of fatty acids on energy and N balances, total tract digestibility, and milk fatty acids in wk 7 and 16 and to assess total lactation responses. During balance measurements, fatty acids constituted 4.1, 6.8, and 8.6% of DM in control, oilseed, and oilseed plus protected fatty acid diets. Fat additions reduced fiber digestion (attributed to oilseed) and, to some degree, DMI and milk yield, but enhanced fat test without affecting protein percentage. Supplementary fat increased the proportion of C18:0 in milk at the expense of short-chain fatty acids. Supplemental oilseed with or without protected fatty acids reduced total heat production by 6% and reduced heat in excess of maintenance by 8%. Best estimates of NEL in linted whole cottonseed and of fat in Megalac were 1.81 and 5.69 Mcal/kg of DM. In total lactation, primiparous cows yielded more milk and FCM when fed oilseed plus Megalac and less of each when fed oilseed alone than controls. In pluriparous cows, milk yield was reduced by 2.7 kg/d relative to other treatments when oilseed plus Megalac was fed; FCM yield increased about 2 kg/d only when oilseed was supplemented alone. Overall, data suggest that basal ration fat and oilseed supplementation were too high or that supplementation should have been delayed until feed intake was higher.     

Energy and material balance of CO2 capture from ambient air

Current Carbon Capture and Storage (CCS) technologies focus on large, stationary sources that produce approximately 50% of global CO2 emissions. We propose an industrial technology that captures CO2 directly from ambient air to target the remaining emissions. First, a wet scrubbing technique absorbs CO2 into a sodium hydroxide solution. The resultant carbonate is transferred from sodium ions to calcium ions via causticization. The captured CO2 is released from the calcium carbonate through thermal calcination in a modified kiln. The energy consumption is calculated as 350 kJ/mol of CO2 captured. It is dominated by the thermal energy demand of the kiln and the mechanical power required for air movement. The low concentration of CO2 in air requires a throughput of 3 million cubic meters of air per ton of CO2 removed, which could result in significant water losses. Electricity consumption in the process results in CO2 emissions and the use of coal power would significantly reduce to net amount captured. The thermodynamic efficiency of this process is low but comparable to other "end of pipe" capture technologies. As another carbon mitigation technology, air capture could allow for the continued use of liquid hydrocarbon fuels in the transportation sector.     

基于遗传算法及仿真技术的服装生产流水线平衡

针对大部分服装企业存在生产流水线编制效率较低以及生产周期长的普遍现象,提出一种服装工序编排方案自动生成和单件流生产线仿真运行的方法。首先分析服装生产工序编排方法和影响因素,采用拓扑方法和遗传算法相结合,在MatLab(R2016b)软件中建立自动优化模型,实现工序的自动编排;然后考虑服装生产数量和生产线设备情况,采用仿真技术,在Plant Simulation仿真软件中,根据实际生产对工序编排方案进行流水线仿真运行,得出直观可视的仿真结果,实现流水线平衡再优化。生产实例验证表明,流水线编制效率为90.8%,比原有效率提高12.8%,节省流水线编排方案在投产前的平衡调试时间,生产周期缩短。     

Modeling the relative GHG emissions of conventional and shale gas production

Recent reports show growing reserves of unconventional gas are available and that there is an appetite from policy makers, industry, and others to better understand the GHG impact of exploiting reserves such as shale gas. There is little publicly available data comparing unconventional and conventional gas production. Existing studies rely on national inventories, but it is not generally possible to separate emissions from unconventional and conventional sources within these totals. Even if unconventional and conventional sites had been listed separately, it would not be possible to eliminate site-specific factors to compare gas production methods on an equal footing. To address this difficulty, the emissions of gas production have instead been modeled. In this way, parameters common to both methods of production can be held constant, while allowing those parameters which differentiate unconventional gas and conventional gas production to vary. The results are placed into the context of power generation, to give a ″well-to-wire″ (WtW) intensity. It was estimated that shale gas typically has a WtW emissions intensity about 1.8-2.4% higher than conventional gas, arising mainly from higher methane releases in well completion. Even using extreme assumptions, it was found that WtW emissions from shale gas need be no more than 15% higher than conventional gas if flaring or recovery measures are used. In all cases considered, the WtW emissions of shale gas powergen are significantly lower than those of coal.     

Potential restrictions for CO2 sequestration sites due to shale and tight gas production

Carbon capture and geological sequestration is the only available technology that both allows continued use of fossil fuels in the power sector and reduces significantly the associated CO(2) emissions. Geological sequestration requires a deep permeable geological formation into which captured CO(2)can be injected, and an overlying impermeable formation, called a caprock, that keeps the buoyant CO(2) within the injection formation. Shale formations typically have very low permeability and are considered to be good caprock formations. Production of natural gas from shale and other tight formations involves fracturing the shale with the explicit objective to greatly increase the permeability of the shale. As such, shale gas production is in direct conflict with the use of shale formations as a caprock barrier to CO(2) migration. We have examined the locations in the United States where deep saline aquifers, suitable for CO(2) sequestration, exist, as well as the locations of gas production from shale and other tight formations. While estimated sequestration capacity for CO(2) sequestration in deep saline aquifers is large, up to 80% of that capacity has areal overlap with potential shale-gas production regions and, therefore, could be adversely affected by shale and tight gas production. Analysis of stationary sources of CO(2) shows a similar effect: about two-thirds of the total emissions from these sources are located within 20 miles of a deep saline aquifer, but shale and tight gas production could affect up to 85% of these sources. These analyses indicate that colocation of deep saline aquifers with shale and tight gas production could significantly affect the sequestration capacity for CCS operations. This suggests that a more comprehensive management strategy for subsurface resource utilization should be developed.     

Technical, economical, and climate-related aspects of biochar production technologies: a literature review

For the development of commercial biochar projects, reliable data on biochar production technologies is needed. For this purpose, peer-reviewed scientific articles on carbonization technologies (pyrolysis, gasification, hydrothermal carbonization, and flash carbonization) have been analyzed. Valuable information is provided by papers on pyrolysis processes, less information is available on gasification processes, and few papers about hydrothermal and flash carbonization technologies were identified. A wide range of data on the costs of char production (between 51 US$ per tonne pyrolysis biochar from yard waste and 386 US$ per tonne retort charcoal) and on the GHG balance of biochar systems (between -1054 kg CO(2)e and +123 kg CO(2)e per t dry biomass feedstock) have been published. More data from pilot projects are needed to improve the evaluation of biochar production technologies. Additional research on the influence of biochar application on surface albedo, atmospheric soot concentration, and yield responses is necessary to assess the entire climate impact of biochar systems. Above all, further field trials on the ability of different technologies to produce chars for agricultural soils and carbon sequestration are essential for future technology evaluation.     

油菜秆快速热裂解产物的成分研究及利用前景分析

应用裂解-气相色谱质谱（PY-GC/MS）分析技术,利用5150全自动快速裂解仪闪速升温功能,对油菜秆在900℃时快速热裂解产物的主要组分及其相对含量进行了分析。分离并确认出分子量在40～650D范围的25种化合物,主要是烃类含氧有机化合物（包括酚、酯、醛、酮、醇、酐、酸类）和少数不饱和烃类化合物。分析表明,裂解物中有多种成分是重要的化工原料,利用新技术对这些组分进行分离提纯,可以得到宝贵的化工原料。     

Land use greenhouse gas emissions from conventional oil production and oil sands

Debates surrounding the greenhouse gas (GHG) emissions from land use of biofuels production have created a need to quantify the relative land use GHG intensity of fossil fuels. When contrasting land use GHG intensity of fossil fuel and biofuel production, it is the energy yield that greatly distinguishes the two. Although emissions released from land disturbed by fossil fuels can be comparable or higher than biofuels, the energy yield of oil production is typically 2-3 orders of magnitude higher, (0.33-2.6, 0.61-1.2, and 2.2 5.1 PJ/ha) for conventional oil production, oil sands surface mining, and in situ production, respectively). We found that land use contributes small portions of GHGs to life cycle emissions of California crude and in situ oil sands production ( <0.4% or < 0.4 gCO?e/MJ crude refinery feedstock) and small to modest portions for Alberta conventional oil (0.1-4% or 0.1-3.4 gCO?e/MJ) and surface mining of oil sands (0.9-11% or 0.8-10.2 gCO?e/MJ).Our estimates are based on assumptions aggregated over large spatial and temporal scales and assuming 100% reclamation. Values on finer spatial and temporal scales that are relevant to policy targets need to account for site-specific information, the baseline natural and anthropogenic disturbance.     

The relevance of methane emissions from beef production and the challenges of the Argentinean beef production platform

The livestock sector faces the challenge to respond to the growing demand for animal protein from an expanding population while reducing environmental impact through GHG emissions. Globally about 2.836 million tons of CO₂-eq were emitted by the beef production sector equivalent to 46,2 kg CO₂-eq per kg carcass weight (CW). From the 1.485 million cattle head spread out over the world, 82% are on extensive grazing systems while only 18% are on high productive intensive systems. Among the top ten beef exporter countries, five are located in Latin America accounting a quarter of the global stock and two of them, Argentina and Uruguay, produce on temperate pastures under grazing systems. In Argentina, the livestock area was reduced in favor of increasing the grain cropping area, which took place in the last two decades. Production systems were intensified to maintain cattle stock. Cattle programs changed from 100% pasture to pasture supplemented with cereal grains and conserved forages, and confinement on grain feeding for fattening was incorporated. Due to land sharing competition with cash crops, no increment of cattle stock is expected therefore improving production efficiency appears as the only way to increase beef production while reducing methane emissions intensity. Beef produced on intensive grazing systems on supplemented pastures maintained organoleptic, nutritional and lipid profile than that of beef produced on pure grazing systems.