Research developments in methods to reduce the carbon footprint of the food system: a review

Global warming is a worldwide issue with its evident impact across a wide range of systems and sectors. It is caused by a number of greenhouse gases (GHGs) emissions, in which food system has made up of a large part. Recently, reduction of GHG emissions has become an urgent issue to be resolved in the food system. Many governments and organizations are making great endeavors to alleviate the adverse effect of this phenomenon. In this review, methods to reduce the carbon footprint within the life cycle of a food system are presented from the technical, consumption behavior and environmental policies perspectives. The whole food system including raw material acquisition, processing, packaging, preservation, transportation, consumption, and disposal are covered. Improving management techniques, and adopting advanced technology and equipment are critical for every stage of a food system. Rational site selection is important to alleviate the influence of land use change. In addition, environmental choices of packaging stage, reduction in refrigeration dependence, and correct waste treatment are essential to reduce the total carbon footprint of the production. However, only technical methods cannot radically reverse the trend of climate change, as consumption behaviors present a great deal of influence over climate change. Appropriate purchase patterns and substitution within food product categories by low carbon products can reduce GHG emissions. Development of methods to calculate the carbon footprint of every kind of food and its processing technology enable people to make environmental choice. Policy can shape and cultivate the new code of consumption and influence the direction of emerging technology and science. From political perspectives, government intervention and carbon offset are common tools, especially for carbon tax and a real or implicit price of carbon. Finally, by mitigating the methodologies described above, the rate and magnitude of climate changes can be also reduced to some extent.

Life Cycle Environmental Impacts of Electricity from Biogas Produced by Anaerobic Digestion

The aim of this study was to evaluate life cycle environmental impacts associated with the generation of electricity from biogas produced by the anaerobic digestion (AD) of agricultural products and waste. Five real plants in Italy were considered, using maize silage, slurry, and tomato waste as feedstocks and cogenerating electricity and heat; the latter is not utilized. The results suggest that maize silage and the operation of anaerobic digesters, including open storage of digestate, are the main contributors to the impacts of biogas electricity. The system that uses animal slurry is the best option, except for the marine and terrestrial ecotoxicity. The results also suggest that it is environmentally better to have smaller plants using slurry and waste rather than bigger installations, which require maize silage to operate efficiently. Electricity from biogas is environmentally more sustainable than grid electricity for seven out of 11 impacts considered. However, in comparison with natural gas, biogas electricity is worse for seven out of 11 impacts. It also has mostly higher impacts than other renewables, with a few exceptions, notably solar photovoltaics. Thus, for the AD systems and mesophilic operating conditions considered in this study, biogas electricity can help reduce greenhouse gas (GHG) emissions relative to a fossil-intensive electricity mix; however, some other impacts increase. If mitigation of climate change is the main aim, other renewables have a greater potential to reduce GHG emissions. If, in addition to this, other impacts are considered, then hydro, wind, and geothermal power are better alternatives to biogas electricity. However, utilization of heat would improve significantly its environmental sustainability, particularly global warming potential, summer smog, and the depletion of abiotic resources and the ozone layer. Further improvements can be achieved by banning open digestate storage to prevent methane emissions and regulating digestate spreading onto land to minimize emissions of ammonia and related environmental impacts.

Life Cycle Environmental Impacts of Electricity from Biogas Produced by Anaerobic Digestion

The aim of this study was to evaluate life cycle environmental impacts associated with the generation of electricity from biogas produced by the anaerobic digestion (AD) of agricultural products and waste. Five real plants in Italy were considered, using maize silage, slurry, and tomato waste as feedstocks and cogenerating electricity and heat; the latter is not utilized. The results suggest that maize silage and the operation of anaerobic digesters, including open storage of digestate, are the main contributors to the impacts of biogas electricity. The system that uses animal slurry is the best option, except for the marine and terrestrial ecotoxicity. The results also suggest that it is environmentally better to have smaller plants using slurry and waste rather than bigger installations, which require maize silage to operate efficiently. Electricity from biogas is environmentally more sustainable than grid electricity for seven out of 11 impacts considered. However, in comparison with natural gas, biogas electricity is worse for seven out of 11 impacts. It also has mostly higher impacts than other renewables, with a few exceptions, notably solar photovoltaics. Thus, for the AD systems and mesophilic operating conditions considered in this study, biogas electricity can help reduce greenhouse gas (GHG) emissions relative to a fossil-intensive electricity mix; however, some other impacts increase. If mitigation of climate change is the main aim, other renewables have a greater potential to reduce GHG emissions. If, in addition to this, other impacts are considered, then hydro, wind, and geothermal power are better alternatives to biogas electricity. However, utilization of heat would improve significantly its environmental sustainability, particularly global warming potential, summer smog, and the depletion of abiotic resources and the ozone layer. Further improvements can be achieved by banning open digestate storage to prevent methane emissions and regulating digestate spreading onto land to minimize emissions of ammonia and related environmental impacts.

Environmental analysis of the life cycle emissions of 2-methyl tetrahydrofuran solvent manufactured from renewable resources

An environmental analysis has been conducted to determine the cradle to gate life cycle emissions to manufacture the green solvent, 2-methyl tetrahydrofuran. The solvent is considered a greener chemical since it can be manufactured from renewable resources with a lower life cycle footprint. Analyses have been performed using different methods to show greenness in both its production and industrial use. This solvent can potentially be substituted for other ether and chlorinated solvents commonly used in organometallic and biphasic reactions steps in pharmaceutical and fine chemical syntheses. The 2-methyl tetrahydrofuran made from renewable agricultural by-products is marketed by Penn A Kem under the name ecoMeTHF™. The starting material, 2-furfuraldehyde (furfural), is produced from corn cob waste by converting the available pentosans by acid hydrolysis. An evaluation of each step in the process was necessary to determine the overall life cycle and specific CO2 emissions for each raw material/intermediate produced. Allocation of credits for CO2 from the incineration of solvents made from renewable feedstocks significantly reduced the overall carbon footprint. Using this approach, the overall life cycle emissions for production of 1 kg of ecoMeTHF™ were determined to be 0.191 kg, including 0.150 kg of CO2. Life cycle emissions generated from raw material manufacture represents the majority of the overall environmental impact. Our evaluation shows that using 2-methyl tetrahydrofuran in an industrial scenario results in a 97% reduction in emissions, when compared to typically used solvents such as tetrahydrofuran, made through a conventional chemical route.

Diet-related greenhouse gas emissions assessed by a food frequency questionnaire and validated using 7-day weighed food records

BACKGROUND

The current food system generates about 25 % of total greenhouse gas emissions (GHGE), including deforestation, and thereby substantially contributes to the warming of the earth's surface. To understand the association between food and nutrient intake and GHGE, we therefore need valid methods to assess diet-related GHGE in observational studies.

METHODS

Life cycle assessment (LCA) studies assess the environmental impact of different food items. We linked LCA data expressed as kg carbon dioxide equivalents (CO2e) per kg food product to data on food intake assessed by the food frequency questionnaire (FFQ) Meal-Q and validated it against a 7-day weighed food record (WFR). 166 male and female volunteers aged 20-63 years completed Meal-Q and the WFR, and their food intake was linked to LCA data.

RESULTS

The mean GHGE assessed with Meal-Q was 3.76 kg CO2e per day and person, whereas it was 5.04 kg CO2e using the WFR. The energy-adjusted and deattenuated Pearson and Spearman correlation coefficients were 0.68 and 0.70, respectively. Moreover, compared to the WFR, Meal-Q provided a good ranking ability, with 90 % of the participants classified into the same or adjacent quartile according to their daily average CO2e. The Bland-Altman plot showed an acceptable level of agreement between the two methods and the reproducibility of Meal-Q was high.

CONCLUSIONS

This is the first study validating the assessment of diet-related GHGE by a questionnaire. The results suggest that Meal-Q is a useful tool for studying the link between food habits and CO2e in future epidemiological studies.

A Protocol for the Global Sensitivity Analysis of Impact Assessment Models in Life Cycle Assessment

The life cycle assessment (LCA) framework has established itself as the leading tool for the assessment of the environmental impact of products. Several works have established the need of integrating the LCA and risk analysis methodologies, due to the several common aspects. One of the ways to reach such integration is through guaranteeing that uncertainties in LCA modeling are carefully treated. It has been claimed that more attention should be paid to quantifying the uncertainties present in the various phases of LCA. Though the topic has been attracting increasing attention of practitioners and experts in LCA, there is still a lack of understanding and a limited use of the available statistical tools. In this work, we introduce a protocol to conduct global sensitivity analysis in LCA. The article focuses on the life cycle impact assessment (LCIA), and particularly on the relevance of global techniques for the development of trustable impact assessment models. We use a novel characterization model developed for the quantification of the impacts of noise on humans as a test case. We show that global SA is fundamental to guarantee that the modeler has a complete understanding of: (i) the structure of the model and (ii) the importance of uncertain model inputs and the interaction among them.

Life Cycle Assessment of Titania Perovskite Solar Cell Technology for Sustainable Design and Manufacturing

Perovskite solar cells have attracted enormous attention in recent years due to their low cost and superior technical performance. However, the use of toxic metals, such as lead, in the perovskite dye and toxic chemicals in perovskite solar cell manufacturing causes grave concerns for its environmental performance. To understand and facilitate the sustainable development of perovskite solar cell technology from its design to manufacturing, a comprehensive environmental impact assessment has been conducted on titanium dioxide nanotube based perovskite solar cells by using an attributional life cycle assessment approach, from cradle to gate, with manufacturing data from our laboratory-scale experiments and upstream data collected from professional databases and the literature. The results indicate that the perovskite dye is the primary source of environmental impact, associated with 64.77% total embodied energy and 31.38% embodied materials consumption, contributing to more than 50% of the life cycle impact in almost all impact categories, although lead used in the perovskite dye only contributes to about 1.14% of the human toxicity potential. A comparison of perovskite solar cells with commercial silicon and cadmium-tellurium solar cells reveals that perovskite solar cells could be a promising alternative technology for future large-scale industrial applications.

Packaging waste prevention activities: A life cycle assessment of the effects on a regional waste management system

A life cycle assessment was carried out to evaluate the effects of two packaging waste prevention activities on the overall environmental performance of the integrated municipal waste management system of Lombardia region, Italy. The activities are the use of refined tap water instead of bottled water for household consumption and the substitution of liquid detergents packaged in single-use containers by those distributed 'loose' through self-dispensing systems and refillable containers. A 2020 baseline scenario without waste prevention is compared with different waste prevention scenarios, where the two activities are either separately or contemporaneously implemented, by assuming a complete substitution of the traditional product(s). The results show that, when the prevention activities are carried out effectively, a reduction in total waste generation ranging from 0.14% to 0.66% is achieved, corresponding to a 1-4% reduction of the affected packaging waste fractions (plastics and glass). However, the improvements in the overall environmental performance of the waste management system can be far higher, especially when bottled water is substituted. In this case, a nearly 0.5% reduction of the total waste involves improvements ranging mostly between 5 and 23%. Conversely, for the substitution of single-use packaged liquid detergents (0.14% reduction of the total waste), the achieved improvements do not exceed 3% for nearly all impact categories.

Relating the carbon footprint of milk from Irish dairy farms to economic performance

Mitigating greenhouse gas (GHG) emissions per unit of milk or the carbon footprint (CF) of milk is a key issue for the European dairy sector given rising concerns over the potential adverse effects of climate change. Several strategies are available to mitigate GHG emissions, but producing milk with a low CF does not necessarily imply that a dairy farm is economically viable. Therefore, to understand the relationship between the CF of milk and dairy farm economic performance, the farm accountancy network database of a European Union nation (Ireland) was applied to a GHG emission model. The method used to quantify GHG emissions was life cycle assessment (LCA), which was independently certified to comply with the British standard for LCA. The model calculated annual on- and off-farm GHG emissions from imported inputs (e.g., electricity) up to the point milk was sold from the farm in CO2-equivalent (CO2-eq). Annual GHG emissions computed using LCA were allocated to milk based on the economic value of dairy farm products and expressed per kilogram of fat- and protein-corrected milk (FPCM). The results showed for a nationally representative sample of 221 grass-based Irish dairy farms in 2012 that gross profit averaged € 0.18/L of milk and € 1,758/ha and gross income was € 40,899/labor unit. Net profit averaged € 0.08/L of milk and € 750/ha and net income averaged € 18,125/labor unit. However, significant variability was noted in farm performance across each financial output measure. For instance, net margin per hectare of the top one-third of farms was 6.5 times higher than the bottom third. Financial performance measures were inversely correlated with the CF of milk, which averaged 1.20 kg of CO2-eq/kg of FPCM but ranged from 0.60 to 2.13 kg of CO2-eq/kg of FPCM. Partial least squares regression analysis of correlations between financial and environmental performance indicated that extending the length of the grazing season and increasing milk production per hectare or per cow reduced the CF of milk and increased farm profit. However, where higher milk production per hectare was associated with greater concentrate feeding, this adversely affected the CF of milk and economic performance by increasing both costs and off-farm emissions. Therefore, to mitigate the CF of milk and improve economic performance, grass-based dairy farms should not aim to only increase milk output, but instead target increasing milk production per hectare from grazed grass.

Novel pathways for fuels and lubricants from biomass optimized using life-cycle greenhouse gas assessment

Decarbonizing the transportation sector is critical to achieving global climate change mitigation. Although biofuels will play an important role in conventional gasoline and diesel applications, bioderived solutions are particularly important in jet fuels and lubricants, for which no other viable renewable alternatives exist. Producing compounds for jet fuel and lubricant base oil applications often requires upgrading fermentation products, such as alcohols and ketones, to reach the appropriate molecular-weight range. Ketones possess both electrophilic and nucleophilic functionality, which allows them to be used as building blocks similar to alkenes and aromatics in a petroleum refining complex. Here, we develop a method for selectively upgrading biomass-derived alkyl methyl ketones with >95% yields into trimer condensates, which can then be hydrodeoxygenated in near-quantitative yields to give a new class of cycloalkane compounds. The basic chemistry developed here can be tailored for aviation fuels as well as lubricants by changing the production strategy. We also demonstrate that a sugarcane biorefinery could use natural synergies between various routes to produce a mixture of lubricant base oils and jet fuels that achieve net life-cycle greenhouse gas savings of up to 80%.

Sustainability and shared smart and mutual--green growth (SSaM-GG) in Korean medical waste management

Since medical insurance was introduced in the Republic of Korea, there have been several increases concerning medical waste. In order to solve these problems, we have applied life cycle assessment and life cycle cost. But these methods cannot be a perfect decision-making tool because they can only evaluate environmental and economic burdens. Thus, as one of many practical methods the shared smart and mutual - green growth considers economic growth, environmental protection, social justice, science technology and art, and mutual voluntarism when applied to medical waste management in the Republic of Korea. Four systems were considered: incineration, incineration with heat recovery, steam sterilisation, and microwave disinfection. This research study aimed to assess pollutant emissions from treatment, transport, and disposal. Global warming potential, photochemical oxidant creation potential, acidifications potential, and human toxicity are considered to be environmental impacts. Total investment cost, transport cost, operation, and maintenance cost for the medical waste are considered in the economy evaluations though life cycle cost. The social development, science technology and art, and mutual voluntarism are analysed through the Delphi-method conducted by expert groups related to medical waste. The result is that incineration with heat recovery is the best solution. However, when heat recovery is impossible, incineration without heat recovery becomes the next best choice. That is why 95% of medical waste is currently treated by both incineration and incineration with heat recovery within the Republic of Korea.

Environmental implications of anaerobic digestion for manure management in dairy farms in Mexico: a life cycle perspective

The environmental profile of milk production in Mexico was analysed for three manure management scenarios: fertilization (F), anaerobic digestion (AD) and enhanced anaerobic digestion (EAD). The study used the life cycle assessment (LCA) technique, considering a 'cradle-to-gate' approach. The assessment model was constructed using SimaPro LCA software, and the life cycle impact assessment was performed according to the ReCiPe method. Dairy farms with AD and EAD scenarios were found to exhibit, respectively, 12% and 27% less greenhouse gas emissions, 58% and 31% less terrestrial acidification, and 3% and 18% less freshwater eutrophication than the F scenario. A different trend was observed in the damage to resource availability indicator, as the F scenario presented 6% and 22% less damage than the EAD and AD scenarios, respectively. The magnitude of environmental damage from milk production in the three dairy manure management scenarios, using a general single score indicator, was 0.118, 0.107 and 0.081 Pt/L of milk for the F, AD and EAD scenarios, respectively. These results indicate that manure management systems with anaerobic digestion can improve the environmental profile of each litre of milk produced.

Simulation tool for assessing the release and environmental distribution of nanomaterials

An integrated simulation tool was developed for assessing the potential release and environmental distribution of nanomaterials (RedNano) based on a life cycle assessment approach and multimedia compartmental modeling coupled with mechanistic intermedia transport processes. The RedNano simulation tool and its web-based software implementation enables rapid "what-if?" scenario analysis, in order to assess the response of an environmental system to various release scenarios of engineered nanomaterials (ENMs). It also allows for the investigation of the impact of geographical and meteorological parameters on ENM distribution in the environment, comparison of the impact of ENM production and potential releases on different regions, and estimation of source release rates based on monitored ENM concentrations. Moreover, the RedNano simulation tool is suitable for research, academic, and regulatory purposes. Specifically, it has been used in environmental multimedia impact assessment courses at both the undergraduate and graduate levels. The RedNano simulation tool can also serve as a decision support tool to rapidly and critically assess the potential environmental implications of ENMs and thus ensure that nanotechnology is developed in a productive and environmentally responsible manner.

Evaluation of operational, economic, and environmental performance of mixed and selective collection of municipal solid waste: Porto case study

This article describes an accurate methodology for an operational, economic, and environmental assessment of municipal solid waste collection. The proposed methodological tool uses key performance indicators to evaluate independent operational and economic efficiency and performance of municipal solid waste collection practices. These key performance indicators are then used in life cycle inventories and life cycle impact assessment. Finally, the life cycle assessment environmental profiles provide the environmental assessment. We also report a successful application of this tool through a case study in the Portuguese city of Porto. Preliminary results demonstrate the applicability of the methodological tool to real cases. Some of the findings focus a significant difference between average mixed and selective collection effective distance (2.14 km t(-1); 16.12 km t(-1)), fuel consumption (3.96 L t(-1); 15.37 L t(-1)), crew productivity (0.98 t h(-1) worker(-1); 0.23 t h(-1) worker(-1)), cost (45.90 € t(-1); 241.20 € t(-1)), and global warming impact (19.95 kg CO2eq t(-1); 57.47 kg CO2eq t(-1)). Preliminary results consistently indicate: (a) higher global performance of mixed collection as compared with selective collection; (b) dependency of collection performance, even in urban areas, on the waste generation rate and density; (c) the decline of selective collection performances with decreasing source-separated material density and recycling collection rate; and (d) that the main threats to collection route efficiency are the extensive collection distances, high fuel consumption vehicles, and reduced crew productivity.

Life cycle analysis within pharmaceutical process optimization and intensification: case study of active pharmaceutical ingredient production

As the demand for new drugs is rising, the pharmaceutical industry faces the quest of shortening development time, and thus, reducing the time to market. Environmental aspects typically still play a minor role within the early phase of process development. Nevertheless, it is highly promising to rethink, redesign, and optimize process strategies as early as possible in active pharmaceutical ingredient (API) process development, rather than later at the stage of already established processes. The study presented herein deals with a holistic life-cycle-based process optimization and intensification of a pharmaceutical production process targeting a low-volume, high-value API. Striving for process intensification by transfer from batch to continuous processing, as well as an alternative catalytic system, different process options are evaluated with regard to their environmental impact to identify bottlenecks and improvement potentials for further process development activities.

Life Cycle Assessment for Proton Conducting Ceramics Synthesized by the Sol-Gel Process

In this report, the environmental aspects of producing proton conducting ceramics are investigated by means of the environmental Life Cycle Assessment (LCA) method. The proton conducting ceramics BaZr_0.8Y_0.2O_3-δ (BZY), BaCe_0.9Y_0.1O_2.95 (BCY10), and Sr(Ce_0.9Zr_0.1)_0.95Yb_0.05O_3-δ (SCZY) were prepared by the sol-gel process. Their material requirements and environmental emissions were inventoried, and their energy requirements were determined, based on actual production data. This latter point makes the present LCA especially worthy of attention as a preliminary indication of future environmental impact. The analysis was performed according to the recommendations of ISO norms 14040 and obtained using the Gabi 6 software. The performance of the analyzed samples was also compared with each other. The LCA results for these proton conducting ceramics production processes indicated that the marine aquatic ecotoxicity potential (MAETP) made up the largest part, followed by fresh-water aquatic ecotoxicity potential (FAETP) and Human Toxicity Potential (HTP). The largest contribution was from energy consumption during annealing and calcinations steps.

Harmonization of initial estimates of shale gas life cycle greenhouse gas emissions for electric power generation

Recent technological advances in the recovery of unconventional natural gas, particularly shale gas, have served to dramatically increase domestic production and reserve estimates for the United States and internationally. This trend has led to lowered prices and increased scrutiny on production practices. Questions have been raised as to how greenhouse gas (GHG) emissions from the life cycle of shale gas production and use compares with that of conventionally produced natural gas or other fuel sources such as coal. Recent literature has come to different conclusions on this point, largely due to differing assumptions, comparison baselines, and system boundaries. Through a meta-analytical procedure we call harmonization, we develop robust, analytically consistent, and updated comparisons of estimates of life cycle GHG emissions for electricity produced from shale gas, conventionally produced natural gas, and coal. On a per-unit electrical output basis, harmonization reveals that median estimates of GHG emissions from shale gas-generated electricity are similar to those for conventional natural gas, with both approximately half that of the central tendency of coal. Sensitivity analysis on the harmonized estimates indicates that assumptions regarding liquids unloading and estimated ultimate recovery (EUR) of wells have the greatest influence on life cycle GHG emissions, whereby shale gas life cycle GHG emissions could approach the range of best-performing coal-fired generation under certain scenarios. Despite clarification of published estimates through harmonization, these initial assessments should be confirmed through methane emissions measurements at components and in the atmosphere and through better characterization of EUR and practices.

Overview of current biological and thermo-chemical treatment technologies for sustainable sludge management

Sludge is a semi-solid residue produced from wastewater treatment processes. It contains biodegradable and recalcitrant organic compounds, as well as pathogens, heavy metals, and other inorganic constituents. Sludge can also be considered a source of nutrients and energy, which could be recovered using economically viable approaches. In the present paper, several commonly used sludge treatment processes including land application, composting, landfilling, anaerobic digestion, and combustion are reviewed, along with their potentials for energy and product recovery. In addition, some innovative thermo-chemical techniques in pyrolysis, gasification, liquefaction, and wet oxidation are briefly introduced. Finally, a brief summary of selected published works on the life cycle assessment of a variety of sludge treatment and end-use scenarios is presented in order to better understand the overall energy balance and environmental burdens associated with each sludge treatment pathway. In all scenarios investigated, the reuse of bioenergy and by-products has been shown to be of crucial importance in enhancing the overall energy efficiency and reducing the carbon footprint.

Assessment methods for solid waste management: A literature review

Assessment methods are common tools to support decisions regarding waste management. The objective of this review article is to provide guidance for the selection of appropriate evaluation methods. For this purpose, frequently used assessment methods are reviewed, categorised, and summarised. In total, 151 studies have been considered in view of their goals, methodologies, systems investigated, and results regarding economic, environmental, and social issues. A goal shared by all studies is the support of stakeholders. Most studies are based on life cycle assessments, multi-criteria-decision-making, cost-benefit analysis, risk assessments, and benchmarking. Approximately 40% of the reviewed articles are life cycle assessment-based; and more than 50% apply scenario analysis to identify the best waste management options. Most studies focus on municipal solid waste and consider specific environmental loadings. Economic aspects are considered by approximately 50% of the studies, and only a small number evaluate social aspects. The choice of system elements and boundaries varies significantly among the studies; thus, assessment results are sometimes contradictory. Based on the results of this review, we recommend the following considerations when assessing waste management systems: (i) a mass balance approach based on a rigid input-output analysis of the entire system, (ii) a goal-oriented evaluation of the results of the mass balance, which takes into account the intended waste management objectives; and (iii) a transparent and reproducible presentation of the methodology, data, and results.

Methods to determine the relative value of genetic traits in dairy cows to reduce greenhouse gas emissions along the chain

Current decisions on breeding in dairy farming are mainly based on economic values of heritable traits, as earning an income is a primary objective of farmers. Recent literature, however, shows that breeding also has potential to reduce greenhouse gas (GHG) emissions. The objective of this paper was to compare 2 methods to determine GHG values of genetic traits. Method 1 calculates GHG values using the current strategy (i.e., maximizing labor income), whereas method 2 is based on minimizing GHG per kilogram of milk and shows what can be achieved if the breeding results are fully directed at minimizing GHG emissions. A whole-farm optimization model was used to determine results before and after 1 genetic standard deviation improvement (i.e., unit change) of milk yield and longevity. The objective function of the model differed between method 1 and 2. Method 1 maximizes labor income; method 2 minimizes GHG emissions per kilogram of milk while maintaining labor income and total milk production at least at the level before the change in trait. Results show that the full potential of the traits to reduce GHG emissions given the boundaries that were set for income and milk production (453 and 441kg of CO2 equivalents/unit change per cow per year for milk yield and longevity, respectively) is about twice as high as the reduction based on maximizing labor income (247 and 210kg of CO2 equivalents/unit change per cow per year for milk yield and longevity, respectively). The GHG value of milk yield is higher than that of longevity, especially when the focus is on maximizing labor income. Based on a sensitivity analysis, it was shown that including emissions from land use change and using different methods for handling the interaction between milk and meat production can change results, generally in favor of milk yield. Results can be used by breeding organizations that want to include GHG values in their breeding goal. To verify GHG values, the effect of prices and emissions factors should be considered, as well as the potential effect of variation between farm types.

Assessment methods for solid waste management: A literature review

Assessment methods are common tools to support decisions regarding waste management. The objective of this review article is to provide guidance for the selection of appropriate evaluation methods. For this purpose, frequently used assessment methods are reviewed, categorised, and summarised. In total, 151 studies have been considered in view of their goals, methodologies, systems investigated, and results regarding economic, environmental, and social issues. A goal shared by all studies is the support of stakeholders. Most studies are based on life cycle assessments, multi-criteria-decision-making, cost-benefit analysis, risk assessments, and benchmarking. Approximately 40% of the reviewed articles are life cycle assessment-based; and more than 50% apply scenario analysis to identify the best waste management options. Most studies focus on municipal solid waste and consider specific environmental loadings. Economic aspects are considered by approximately 50% of the studies, and only a small number evaluate social aspects. The choice of system elements and boundaries varies significantly among the studies; thus, assessment results are sometimes contradictory. Based on the results of this review, we recommend the following considerations when assessing waste management systems: (i) a mass balance approach based on a rigid input-output analysis of the entire system, (ii) a goal-oriented evaluation of the results of the mass balance, which takes into account the intended waste management objectives; and (iii) a transparent and reproducible presentation of the methodology, data, and results.

Life cycle assessment modelling of waste-to-energy incineration in Spain and Portugal

In recent years, waste management systems have been evaluated using a life cycle assessment (LCA) approach. A main shortcoming of prior studies was the focus on a mixture of waste with different characteristics. The estimation of emissions and consumptions associated with each waste fraction in these studies presented allocation problems. Waste-to-energy (WTE) incineration is a clear example in which municipal solid waste (MSW), comprising many types of materials, is processed to produce several outputs. This paper investigates an approach to better understand incineration processes in Spain and Portugal by applying a multi-input/output allocation model. The application of this model enabled predictions of WTE inputs and outputs, including the consumption of ancillary materials and combustibles, air emissions, solid wastes, and the energy produced during the combustion of each waste fraction.

Global evaluation of biofuel potential from microalgae

In the current literature, the life cycle, technoeconomic, and resource assessments of microalgae-based biofuel production systems have relied on growth models extrapolated from laboratory-scale data, leading to a large uncertainty in results. This type of simplistic growth modeling overestimates productivity potential and fails to incorporate biological effects, geographical location, or cultivation architecture. This study uses a large-scale, validated, outdoor photobioreactor microalgae growth model based on 21 reactor- and species-specific inputs to model the growth of Nannochloropsis. This model accurately accounts for biological effects such as nutrient uptake, respiration, and temperature and uses hourly historical meteorological data to determine the current global productivity potential. Global maps of the current near-term microalgae lipid and biomass productivity were generated based on the results of annual simulations at 4,388 global locations. Maximum annual average lipid yields between 24 and 27 m(3)·ha(-1)·y(-1), corresponding to biomass yields of 13 to 15 g·m(-2)·d(-1), are possible in Australia, Brazil, Colombia, Egypt, Ethiopia, India, Kenya, and Saudi Arabia. The microalgae lipid productivity results of this study were integrated with geography-specific fuel consumption and land availability data to perform a scalability assessment. Results highlight the promising potential of microalgae-based biofuels compared with traditional terrestrial feedstocks. When water, nutrients, and CO2 are not limiting, many regions can potentially meet significant fractions of their transportation fuel requirements through microalgae production, without land resource restriction. Discussion focuses on sensitivity of monthly variability in lipid production compared with annual average yields, effects of temperature on productivity, and a comparison of results with previous published modeling assumptions.

How can farming intensification affect the environmental impact of milk production?

The intensification process of the livestock sector has been characterized in recent decades by increasing output of product per hectare, increasing stocking rate, including more concentrated feed in the diet, and improving the genetic merit of the breeds. In dairy farming, the effects of intensification on the environmental impact of milk production are not completely clarified. The aim of the current study was to assess the environmental impacts of dairy production by a life cycle approach and to identify relations between farming intensity and environmental performances expressed on milk and land units. A group of 28 dairy farms located in northern Italy was involved in the study; data collected during personal interviews of farmers were analyzed to estimate emissions (global warming potential, acidification, and eutrophication potentials) and nonrenewable source consumption (energy and land use). The environmental impacts of milk production obtained from the life cycle assessment were similar to those of other recent studies and showed high variability among the farms. From a cluster analysis, 3 groups of farms were identified, characterized by different levels of production intensity. Clusters of farms showed similar environmental performances on product basis, despite important differences in terms of intensification level, management, and structural characteristics. Our study pointed out that, from a product perspective, the most environmentally friendly way to produce milk is not clearly identifiable. However, the principal component analysis showed that some characteristics related to farming intensification, such as milk production per cow, dairy efficiency, and stocking density, were negatively related to the impacts per kilogram of product, suggesting a role of these factors in the mitigation strategy of environmental burden of milk production on a global scale. Considering the environmental burden on a local perspective, the impacts per hectare were positively associated with the intensification level.

Comparison of the environmental footprint of the egg industry in the United States in 1960 and 2010

The US egg industry has evolved considerably over recent decades by incorporating new technologies and production practices. To date, there has been no comprehensive assessment of the resource demand and environmental effects of these changes. This study quantifies the environmental footprint of egg production supply chains in the United States for 2010 compared with 1960 using life cycle assessment. The analysis considers changes in both foreground (e.g., hen production performance) and background (e.g., efficiencies of energy provision, fertilizer production, production of feed inputs, and transport modes) system variables. The results revealed that feed efficiency, feed composition, and manure management are the 3 primary factors that determine the environmental impacts of US egg production. Further research and improvements in these areas will aid in continual reduction of the environmental footprint of the US egg industry over time. Per kilogram of eggs produced, the environmental footprint for 2010 is 65% lower in acidifying emissions, 71% lower in eutrophying emissions, 71% lower in greenhouse gas emissions, and 31% lower in cumulative energy demand compared with 1960. Table egg production was 30% higher in 2010; however, the total environmental footprint was 54% lower in acidifying emissions, 63% lower in eutrophying emissions, 63% lower in greenhouse gas emissions, and 13% lower in cumulative energy demand compared with 1960. Reductions in the environmental footprint over the 50-yr interval considered can be attributed to the following: 27 to 30% due to improved efficiencies of background systems, which outweighed the declining energy return on energy invested for primary energy sources; 30 to 44% due to changes in feed composition; and 28 to 43% due to improved bird performance.