Nitrate accumulation and greenhouse gas emissions during compost storage

Greenhouse gases (CO₂, CH₄ and N₂O) are emitted during livestock manure handling, including composting, storage and land application. However, published data on emission rates of these gases during storage are sparse. In this study, the levels of GHG emissions and N levels during compost storage were investigated. The compost materials were produced by composting livestock manure for 133 d with 0, 10, 20 and 30% phosphogypsum (PG) or 10, 20 and 30% sand amendment. These compost materials were then stored on a clay pad for 233 d. Results from this study indicated that TN content did not change but mineral N content increased significantly during the 233 d storage for all treatments. The higher mineral N content in compost increases its agronomic value. There were only trace amounts of CH₄ and N₂O emissions. The C loss during storage was mainly as CO₂ and accounted for about 2.9 to 10% of total C initially in the compost. This information is vital to livestock manure life cycle analysis, and can be used to develop best manure management strategies that reduce GHG emissions from livestock production. The LRC Contribution No. 387-06006.     

Life cycle emissions of greenhouse gas for ammonia scrubbing technology

It is thought that the CO₂ emissions from coal-fired power plants contribute greatly to the total anthropogenic CO₂ emissions. Ammonia solvent can be used to absorb the CO₂, called ammonia scrubbing. However, as has been pointed out, the production of ammonia would emit CO₂; therefore, the effectiveness of ammonia scrubbing is doubted. The paper focuses on the problem. Two systems are defined in the paper. System I is CO₂ absorption by ammonia scrubbing, and system II is industrial production of ammonium bicarbonate. The total CO₂ emissions of the two systems are calculated by means of life cycle assessment. The paper shows that the total CO₂ emissions of ammonia scrubbing are less than that of the industrial production of fertilizer ammonium bicarbonate. It can be concluded that ammonia scrubbing is an effective way to reduce the anthropogenic CO₂ emissions. This work was presented at the 6 ^th Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006.     

Global estimates of potential mitigation of greenhouse gas emissions by agriculture

Technologies to reduce net emissions of carbon dioxide, methane and nitrous oxide within the agriculture sector were reviewed to estimate the global potential for mitigation of these radiatively active greenhouse gases. Our estimates of the potential reduction of radiative forcing by the agricultural sector range from 1.15-3.3 Gt C equivalents per year. Of the total potential reduction, approximately 32% could result from reduction in CO₂ emissions, 42% of carbon offsets by biofuel production on 15% of existing croplands, 16% from reduced CH₄ emissions and 10% from reduced emissions of N₂O. Agriculture encompasses large regional differences in management practices and rates of potential adoption of mitigation practices. Acceptability of mitigation options will depend on the extent to which sustainable production will be achieved or maintained and benefits will accrue to farmers. Technologies such as no-till farming and strategic fertilizer placement and timing are now being adopted for reasons other than concern for climate change issues. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of climate change on greenhouse gas emissions from arable crop rotations

The DAISY soil–plant–atmosphere model was used to simulate crop production and soil carbon (C) and nitrogen (N) turnover for three arable crop rotations on a loamy sand in Denmark under varying temperature, rainfall, atmospheric CO₂ concentration and N fertilization. The crop rotations varied in proportion of spring sown crops and use of N catch crops (ryegrass). The effects on CO₂ emissions were estimated from simulated changes in soil C. The effects on N₂O emissions were estimated using the IPCC methodology from simulated amounts of N in crop residues and N leaching. Simulations were carried out using the original and a revised parameterization of the soil C turnover. The use of the revised model parameterization increased the soil C and N turnover in the topsoil under baseline conditions, resulting in an increase in crop N uptake of 11 kg N ha^–1 y^–1 in a crop rotation with winter cereals and a reduction of 16 kg N ha^–1 y^–1 in a crop rotation with spring cereals and catch crops. The effect of increased temperature, rainfall and CO₂ concentration on N flows was of the same magnitude for both model parameterizations. Higher temperature and rainfall increased N leaching in all crop rotations, whereas effects on N in crop residues depended on use of catch crops. The total greenhouse gas (GHG) emission increased with increasing temperature. The increase in total GHG emission was 66–234 kg CO₂-eq ha^–1 y^–1 for a temperature increase of 4°C. Higher rainfall increased total GHG emissions most in the winter cereal dominated rotation. An increase in rainfall of 20% increased total GHG emissions by 11–53 kg CO₂-eq ha^–1 y^–1, and a 50% increase in atmospheric CO₂ concentration decreased emissions by 180–269 kg CO₂-eq ha^–1 y^–1. The total GHG emissions increased considerably with increasing N fertilizer rate for a crop rotation with winter cereals, but remained unchanged for a crop rotation with spring cereals and catch crops. The simulated increase in GHG emissions with global warming can be effectively mitigated by including more spring cereals and catch crops in the rotation.     

Technical and policy aspects of strategies to decrease greenhouse gas emissions from agriculture

Agricultural activities greatly contribute to the global net flux of CH₄, N₂O and CO₂ from the terrestrial biosphere into the atmosphere. For CH₄ and N₂O, the net contribution is in the order of 40%. Because of this relatively large contribution, there is an urgent need for the implementation of effective strategies to decrease the net flux of CH₄, N₂O and CO₂ from agriculture. The objectives of this paper are to review the various measures that have been proposed so far and to discuss the constraints and challenges. A large number of suggestions for decreasing emissions of CH₄, N₂O and CO₂ from agriculture can be found in literature. Common to most of these abatement measures is that the suggested potentials to decrease the emissions of CO₂, CH₄ and N₂O from agriculture are large. Common to most of the measures is also the `single gas' and `source-oriented' approach. In most papers it has been implicitly assumed that farmers are able and willing to implement the proposed measures. So far, none of the measures has been consciously implemented and tested at farm scale. The major challenge of policy makers is to formulate effective and efficient policies and measures, using the potentials of the abatement measures proposed so far, and in an international setting with still highly uncertain cause–effect relationships. Major constraints for policy makers follow from the complexities and possible feed back and side effects of abatement measures, from the many stakeholders involved, often with contrasting views, and from the unfamiliarity of farmers with the problem of climate change. Because of the many complexities and interactions involved, policy makers should follow two tracks. Priority should be given to chain-oriented measures, i.e. measures that aim at an increased carbon, nitrogen and water use efficiencies in the whole food chain, above source-oriented measures, i.e. measures that aim at decreased emission from specific sources. Chain-oriented measures should fit in with other environmental policies that aim at increasing resource use efficiency, to be effective and efficient. This revised version was published online in August 2006 with corrections to the Cover Date.     

Inclusion of antibiotics in feed alters greenhouse gas emissions from feedlot manure during composting

In this study, the effects of dietary inclusion of antibiotics on emissions of greenhouse gases (GHG: CO₂, CH₄ and N₂O) from cattle manure during composting were investigated. Manure was collected at the end of two feeding trials in 2005 and 2006 in which feedlot cattle were assigned to one of five dietary groups: (1) Control: no antibiotics added; (2) TYL11: tylosin at 11 mg kg⁻¹ feed; (3) CTC11: chlortetracycline at 11 mg kg⁻¹ feed; (4) CTC44: chlortetracycline at 44 mg kg⁻¹ feed; and CTC44SMZ44: chlortetracycline and sulfamethazine, each at 44 mg kg⁻¹ feed. Open windrows were constructed and the rate of GHG emission was measured periodically. In both years, CO₂ surface emissions were higher (P < 0.05) for treatments CTC11 and CTC44SMZ44 than for the Control. The CO₂ emission rates in 2005 were lower (P < 0.05) than in 2006, reflecting lower total carbon (TC) content in the manure in 2005 (138 ± 2 g kg⁻¹) than in 2006 (245 ± 2 g kg⁻¹). The rate of CH₄ emission varied from 0.006 to 0.232 g C m⁻² day⁻¹. Average values from all four antibiotic treatments were similar (P > 0.05) to the Control in both years. The N₂O emission rates were higher (P > 0.05) with CTC44SMZ44 (2005), TYL11 (2006) and CTC11 (2006) than with Control. While antibiotics do alter GHG emissions from composted feedlot manure, the mechanisms responsible are not clear and warrant further investigation.     

Carbon dioxide sequestration in petrochemical industries with the aim of reduction in greenhouse gas emissions

The mitigation of greenhouse gas emissions to acceptable levels is arguably the greatest environmental challenge these days. Vast utilization of fossil fuels and forest destruction are main causes of CO₂ increase in the atmosphere. Carbon dioxide sequestration that consists of separation, transportation and utilization or storage of CO₂, is one way for reduction of its emission, in which the most costly section is separation. Different methods can be used for carbon dioxide separation such as absorption, membrane separation, adsorption and cryogenic distillation. Economic, technical and environmental issues should be considered in selection of the technology for particular application. Carbon dioxide concentration, temperature, pressure and flow rate are influential operating parameters in the selection of the appropriate separation method. Nowadays, absorption is the worldwide industrial separation method. New researches are focused on developing new stable solvents and efficient column configuration with suitable internals to minimize pressure drop. Membrane separation and adsorption (PSA type) are other long-term alternatives that can increase separation efficiency and decrease separation cost. The level of energy consumption in various separation methods are in the order: chemical absorption>physical absorption>membrane separation. Because of high investment costs, current separation technologies are suitable for large concentrated sources. In the present paper, different processes for carbon dioxide separation are investigated and compared. Available technologies and commercial plants for CO₂ sequestration are provided.     

Game theory approach to optimal design of shale gas supply chains with consideration of economics and life cycle greenhouse gas emissions

This article addresses the optimal design of a non‐cooperative shale gas supply chain based on a game theory approach. Instead of assuming a single stakeholder as in centralized models, we consider different stakeholders, including the upstream shale gas producer and the midstream shale gas processor. Following the Stackelberg game, the shale gas producer is identified as the leader, whose objectives include maximizing its net present value (NPV) and minimizing the life cycle greenhouse gas (GHG) emissions. The shale gas processor is identified as the follower that takes actions after the leader to maximize its own NPV. The resulting problem is a multiobjective mixed‐integer bilevel linear programming problem, which cannot be solved directly using any off‐the‐shelf optimization solvers. Therefore, an efficient projection‐based reformulation and decomposition algorithm is further presented. Based on a case study of the Marcellus shale play, the non‐cooperative model not only captures the interactions between stakeholders but also provides more realistic solutions. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2671–2693, 2017     

Potential of agroforestry for carbon sequestration and mitigation of greenhouse gas emissions from soils in the tropics

Losses of carbon (C) stocks in terrestrial ecosystems and increasing concentrations of greenhouse gases in the atmosphere are challenges that scientists and policy makers have been facing in the recent past. Intensified agricultural practices lead to a reduction in ecosystem carbon stocks, mainly due to removal of aboveground biomass as harvest and loss of carbon as CO₂ through burning and/or decomposition. Evidence is emerging that agroforestry systems are promising management practices to increase aboveground and soil C stocks and reduce soil degradation, as well as to mitigate greenhouse gas emissions. In the humid tropics, the potential of agroforestry (tree-based) systems to sequester C in vegetation can be over 70 Mg C ha^–1, and up to 25 Mg ha^–1 in the top 20 cm of soil. In degraded soils of the sub-humid tropics, improved fallow agroforestry practices have been found to increase top soil C stocks up to 1.6 Mg C ha^–1 y^–1 above continuous maize cropping. Soil C accretion is linked to the structural development of the soil, in particular to increasing C in water stable aggregates (WSA). A review of agroforestry practices in the humid tropics showed that these systems were able to mitigate N₂O and CO₂ emissions from soils and increase the CH₄ sink strength compared to cropping systems. The increase in N₂O and CO₂ emissions after addition of legume residues in improved fallow systems in the sub-humid tropics indicates the importance of using lower quality organic inputs and increasing nutrient use efficiency to derive more direct and indirect benefits from the system. In summary, these examples provide evidence of several pathways by which agroforestry systems can increase C sequestration and reduce greenhouse gas emissions.     

Burning and cultivation effects on greenhouse gas emissions and nutrients in wetland soils from Saskatchewan,Canada

Wetland fringe areas in prairie agricultural landscapes may be subjected to burning of vegetation in autumn followed by cultivation in spring. The objective of this study was to examine the greenhouse gas (CO₂, N₂O and CH₄) emissions and plant nutrient (NO₃, PO₄ and SO₄) supplies in wetland fringe soils as affected by simulated burning + cultivation, at field capacity and saturation moisture content. Using undisturbed soil cores collected from grassed wetland fringes at four sites in southern Saskatchewan, the impacts were examined over a 20-day period. The burning + cultivation treatment generally reduced CO₂ emissions, tended to increase NO₃–N availability, and had no consistent effect on N₂O emissions, or PO₄–P and SO₄–S supply. Production of CH₄ occurred only at one site, and only under saturated conditions. Compared to field capacity, saturation reduced CO₂ emissions and NO₃–N supply, tended to increase PO₄–P availability, and had no consistent effect on N₂O emissions and SO₄–S. The CO₂ emissions and SO₄–S were greater for soil cores with higher organic matter and salinity, respectively. The N₂O emissions were only occasionally related to soil NO₃–N supply rate.     

Manure-DNDC: a biogeochemical process model for quantifying greenhouse gas and ammonia emissions from livestock manure systems

From the point of view of biogeochemistry, manure is a complex of organic matter containing minor minerals. When manure is excreted by animals, it undergoes a series of reactions such as decomposition, hydrolysis, ammonia volatilization, nitrification, denitrification, fermentation etc., from which carbon dioxide (CO₂), nitrous oxide (N₂O), methane (CH₄) and ammonia (NH₃) can be produced. Based on the principles of thermodynamics and reaction kinetics, these reactions are commonly controlled by a group of environmental factors such as temperature, moisture, redox potential, pH, substrate concentration gradient etc. The relations among the environmental factors, the reactions and the gas production have been incorporated in a process-based model, Manure-DNDC, to describe manure organic matter turnover and gas emissions. Using Manure-DNDC, the users can construct a virtual farm by selecting and integrating one or more of the candidate farm facilities (i.e., feedlot, compost, lagoon, anaerobic digester and cropping field) parameterized in the model. Manure-DNDC calculates variations of the environmental factors for each component facility based on its technical specifications, and then utilizes the environmental factors to drive the biogeochemical reactions. To verify the applicability of Manure-DNDC for livestock farms, seven datasets of air emissions measured from farms across the U.S. plus a Scotland pasture were utilized for model tests with encouraging results. A dairy farm in New York was used to assess the impacts of alternative management practices on the gas mitigation. The modeled results showed that a combination of changes in the feed quality, the lagoon coverage and the planted crop type could reduce greenhouse gas emission by 30?% and NH₃ by 36?% at the farm scale.     

The variation of greenhouse gas emissions from soils of various land-use/cover types in Jambi province,Indonesia

We measured fluxes of three greenhouse gases (N₂O, CO₂O and CH₄) from soils of six different land-use types at 27 temporary field sites in Jambi Province, Sumatra, Indonesia. Study sites included natural and logged-over forests; rubber plantation; oil palm plantation; cinnamon plantation; and grassland field. The ranges of N₂O, CO₂ and CH₄ fluxes were 0.13–55.8 gN m-2h-1; 1.38–5.16 g C m-2d-1; –1.27–1.18 mg C m-2d-1, respectively. The averages of N₂O, CO₂ and CH₄ fluxes at 27 sites were 9.4 gN m-2h-1,3.65 g C m-2d-1, –0.45 mg C m-2d-1, respectively. The values of CO₂ and CH₄ fluxes were comparable with those in the reports regarding other humid tropical forests, while the N₂O flux was relatively lower than those of previous reports. The N₂O fluxes in each soil type were correlated with the nitrification rates of soils of 0–5 cm depth. In Andisols, the ratio of the N₂O emission rate to the nitrification rate was possibly smaller than that of the other soil types. There was no clear relationship between N₂O flux and the soil water condition, such as water-filled pore space. Seventeen percent of CH₄ fluxes were positive; according to these positive fluxes, we did not find a good correlation between CH₄ uptake rate and soil properties. Although we performed a chronosequence analysis to produce some hypotheses about the effect of land-use change by a limited amount of sampling at one point in time, further tests are required for the future.     

A short communication on the effect of nitrogen fertilization of willow on yield,combustion emissions and greenhouse gas balance

Nitrogen fertilizer was applied to willow after harvest in 2011, two levels of nitrogen were applied (75; 150 kg N/ha) in addition to a control. The trial was harvested in January 2013, biomass from each treatment was burnt and emissions from combustion were quantified. Nitrogen application increased leaf nitrogen and plant height although there was no difference between the nitrogen treatments. Plant height and maximum stem diameter increased with applied nitrogen at final harvest. Nitrogen fertilization significantly increased yield by 35 % although there was no difference between the two nitrogen treatments. Stem nitrogen content did not differ significantly between treatments and there was no significant difference in NO_x emissions between treatments. A life cycle assessment showed that nitrogen fertilization significantly increased net greenhouse gas benefit by up to 30 % depending on the fuel replaced. The study demonstrated that the application of relatively low levels of nitrogenous fertilizer to willow can significantly improve greenhouse gas mitigation without affecting other aspects of the environment such as air quality.     

工业固废活化钾长石-CO2矿化提钾的生命周期碳排放与成本评价

利用工业固废活化非水溶性钾长石矿,矿化固定二氧化碳（CO₂）并提钾工艺,是同时处理工业固废、开发钾资源、减排CO₂等一举多得的CCUS路线。采用生命周期评价（LCA）方法,以生产含1 t K₂O的钾肥为功能单元,以传统的高炉冶炼钾长石制可溶性钾肥并联产白水泥工艺作为参照,对比评价了两种钾长石-工业固废体系矿化CO₂联产钾肥工艺过程的碳减排潜力和经济性。对工艺从原料开采、运输到产品生产的生命周期的温室气体排放量（简称“碳排放”）和成本进行了全流程的核算,研究了更全面的产品碳排放和成本分配方法。结果表明,无论是碳排放还是经济性,钾长石-工业固废体系矿化CO₂联产钾肥工艺均较传统工艺有很大提高,碳减排潜力分别可达81.16%和20.48%左右,成本可节约34.75%和45.11%左右。     

烟气分析法测试燃煤SO_2释出量的研究

为了有效控制SO2的排放量,有必要研究不同温度下燃煤排放SO2含量的测试方法。介绍了烟气分析法用于测试燃煤可释出SO2含量时的试验方法,其中包括间歇式烟气分析法和连续式烟气分析法。通过分析烟气分析法的精确度及重现性,分析该方法的优缺点,并验证其可行性。结果表明:烟气分析法的精确度和重现性不佳,但是可以及时反映燃煤排放SO2的真实情况。因此在完善测试装置后,烟气分析法作为燃煤SO2的测试方法值得进一步深入研究。     

Canadian greenhouse gas mitigation options in agriculture

In 1991, on farm management practices contributed 57.6 Tg CO₂ equivalent in greenhouse gas emissions, that is, about 10% of the anthropogenic GHG emissions in Canada. Approximately 11% of these emissions were in the form of CO₂, 36% in the form of CH₄ and 53% in the form of N₂O. The CO₂ emissions were from soils; CH₄ emissions were from enteric fermentation and manure, and N₂O emissions were primarily a function of cropping practices and manure management. With the emissions from all other agricultural practices included, such as the emissions from fossil fuels used for transportation, manufacturing, food processing etc., the agricultural sector's contributions were about 15% of Canada's emissions. In this publication, several options are examined as to their potential for reducing greenhouse gas emissions. These involve soil and crop management, soil nutrient management, improved feeding strategies, and carbon storage in industrial by-products. The Canadian Economic Emissions Model for Agriculture (CEEMA) was used to predict the greenhouse gas emissions for the year 2010, as well as the impact of mitigation options on greenhouse gas emissions from the agricultural sector. This model incorporates the Canadian Regional Agricultural sub-Model (CRAM), which predicts the activities related to agriculture in Canada up to 2010, as well as a Greenhouse Gas Emissions sub-Model (GGEM), which estimates the greenhouse gas emissions associated with the various agricultural activities. The greenhouse gas emissions from all agricultural sources were 90.5 Tg CO₂ equivalent in 1991. Estimates based on CEEMA for the year 2010 indicate emissions are expected to be 98.0 Tg CO₂ equivalent under a business as usual scenario, which assumes that the present trends in management practices will continue. The agricultural sector will then need to reduce its emissions by about 12.9 Tg CO₂ equivalent below 2010 forecasted emissions, if it is to attain its part of the Canadian government commitment made in Kyoto. Technologies focusing on increasing the soil carbon sink, reducing greenhouse gas emissions and improving the overall farming efficiency, need to be refined and developed as best management practices. The soils carbon sink can be increased through reduced tillage, reduced summer fallowing, increased use of grasslands and forage crops, etc. Key areas for the possible reduction of greenhouse gas emissions are improved soil nutrient management, improved manure storage and handling, better livestock grazing and feeding strategies, etc. The overall impact of these options is dependent on the adoption rate. Agriculture's greenhouse gas reduction commitment could probably be met if soils are recognized as a carbon sink under the Kyoto Accord and if a wide range of management practices are adopted on a large scale. None of these options can currently be recommended as measures because their socio-economic aspects have not been fully evaluated and there are still too many uncertainties in the emission estimates. This revised version was published online in August 2006 with corrections to the Cover Date.     

Herd concentration areas create greenhouse gas hotspots

Nutrient Cycling in Agroecosystems - Herd concentration areas (HCAs) (e.g. laneways, water troughs, shaded areas), where cattle spend a larger proportion of their time relative to other farm areas,...     

Reduction of greenhouse gas emissions via flexible operation of cross-sector integrated energy systems under uncertainties in demand,fuel prices,and solar irradiation

This work investigates how the flexible operation of the light industrial plants integrated in a cross-sector energy cluster with community energy systems can achieve further greenhouse gas (GHG) reductions under uncertainties associated with natural gas prices, solar irradiation, as well as heating, cooling, and electricity demand. The optimal flexible operation and design of a cross-sector integrated cluster comprising a bakery plant, a brewery, a confectionery plant, a residential building, and a supermarket under uncertainties are compared to the operation and design of systems without uncertainties. When uncertainties are considered, the overall GHG emissions of the integrated system with steady industrial production rates for all uncertainty scenarios are over 4% higher than the integrated system in the deterministic scenario (a single scenario). Flexible operation of the industrial plants, whereby production rates are varied throughout the day, contributes an additional 3% reduction in GHG emissions under uncertainties, where the GHG emissions are only 1% higher than the deterministic scenario. Additionally, the system with flexible production rates purchases over 14.3% less electricity from the grid and uses over 72.2% less natural gas for operating the backup boiler, which relies less on supplementary energy resources. This shows that optimally designed integrated systems with flexible industry production schedules are resilient to uncertainties in energy demands, daily weather fluctuations, and fuel prices.