Kg Of CO2e Research Articles

Carbon Footprint Estimation in Road Construction: La Abundancia–Florencia Case Study

The environmental impact of road construction and rehabilitation can be associated with the increase of greenhouse gas (GHG) emissions, which are highly related to climate change. Consequently, departments of transportation have recently focused on the development and implementation of tools to evaluate the performance of projects and minimize GHG emissions. An example is the use of life cycle assessment (LCA) to analyze and quantify the environmental impact of a product, system, or process, from cradle to grave. In this regard, the present case study quantifies the carbon footprint associated with the construction of the La Abundancia–Florencia highway, located in the province of San Carlos in Costa Rica. The analysis is also intended to generate consciousness both in the public and private sectors on the environmental impacts of road construction. After an LCA study, it was determined that the construction of the hot mix asphalt (HMA) layer generates a carbon footprint of 65.8 kg of CO2e per km of road. In addition, it was evident that HMA production generates the greatest environmental impact, among all the considered LCA production and construction stages, with a GHG contribution of 38% to 39% from bitumen only. Consequently, special attention to HMA production is required in order to minimize GHG emissions.

Five financial incentives to revive the Gulf of Mexico dead zone and Mississippi basin soils

A central challenge in the Mississippi River Basin is how to continue to support profitable agricultural production, provide water supply, flood control, transportation, and other benefits, while reducing the current burden of environmental degradation. Several practices have been shown to reduce nutrient runoff and water pollution, and improve soil fertility, while often yielding profits for farmers. Yet many of these beneficial practices remain underutilized. Participants at an expert workshop identified five candidate financial mechanisms that could increase adoption of these beneficial farming practices in four focal Midwest states in the next five years: crop insurance premium subsidies, transformation of the private service provider business model, expansion and targeting of 2019 U.S. Farm Bill funding, development of new state funds, and direction of post-disaster federal funds towards habitat restoration, particularly in floodplains. This study provides rough approximations of the change in nutrient runoff and greenhouse gas (GHG) emissions, the annualized costs, and the nutrient and GHG reductions per dollar likely to result from deployment of each financial mechanism. Based upon these approximations, the adoption of these programs could reduce annual nitrate flows at the outlet of the Ohio and Upper Mississippi River Basins by 25%, surpassing the intermediate 2025 target (20% reduction) and achieving more than half of the long-term target (45% reduction) set by the Mississippi River/Gulf of Mexico Hypoxia Task Force. These approximations also illustrate that these five mechanisms could provide the same GHG reductions (∼43 Tg CO2e yr−1) as taking 12 coal-fired energy plants offline. The total cost of these five financial mechanisms is estimated at ∼$2.6 billion, or 64 g of nitrates and ∼17 kg of CO2e per dollar spent. These proposed solutions all face political, financial, cultural or institutional challenges, but with industry support, creative political action, and continued communication of both private and public benefits, they can create meaningful nutrient reductions and rebuild soils by 2022.

Ten years of five-a-day policy in the UK: Nutritional outcomes and environmental effects

This paper estimates the impact of policy measures aimed at increasing fruit and vegetable (F&V) consumption in the UK over more than a decade, evaluating changes in purchased quantities and estimating the corresponding greenhouse gas emissions (GHGEs). We use a counterfactual scenario analysis to isolate the effects of the policy from the influences of evolving prices, incomes and socio-demographic factors. Our estimates suggest that the positive effects of the promotion campaigns on F&V purchases (about half a portion per adult equivalent per day) still persist 10 years after the start of the policy implementation, and we find no evidence of a wearout effect. We also provide suggestive evidence that the dietary adjustment which accompanies the increase in F&V intakes translates into a relevant reduction in GHGEs, by an average amount of 3.3kg of CO2e per adult equivalent per month.

Fermentation and distillation of cheese whey: Carbon dioxide-equivalent emissions and water use in the production of whey spirits and white whiskey

Whey disposal can be both an environmental and economic challenge for artisanal creameries. Lactose in whey can be fermented to produce ethanol and subsequently distilled. The objective of this study was to use a process-based life cycle analysis to compare carbon dioxide-equivalent (CO2e) emissions and water usage associated with the artisanal or craft production of clear, unaged spirits using whey or malted barley as fermentation substrate. Differences in production were assessed based on key process differences: energy used, water used, distillation by-product disposal, and mass of CO2 produced during fermentation. For this study, whey was assumed removed from the artisanal creamery waste stream. Quantifiable differences were evaluated per 750-mL (45% alcohol by volume) functional unit and expressed as mass-equivalent CO2 emissions (kg of CO2e) and mass of water (kg) used. The CO2e emissions and water usage were quantified using published data, thermodynamic calculations, and mass-balance calculations for a hypothetical distillation system. The process-based life cycle analysis estimated that distillation of fermented whey reduced overall CO2e emissions by 8.4 kg per functional unit and required 0.44 kg less water added into the production process compared with production of a similar clear, unaged spirit using malted barley as substrate. Our preliminary analysis suggests that conversion to distilled whey spirit is a more environmentally responsible approach compared with landfill disposal of whey.

Life-Cycle Assessment Harmonization and Soil Science Ranking Results on Food-Waste Management Methods.

This study reviewed 147 life cycle studies, with 28 found suitable for harmonizing food waste management methods' climate and energy impacts. A total of 80 scientific soil productivity studies were assessed to rank management method soil benefits. Harmonized climate impacts per kilogram of food waste range from -0.20 kg of carbon dioxide equivalents (CO2e) for anaerobic digestion (AD) to 0.38 kg of CO2e for landfill gas-to-energy (LFGTE). Aerobic composting (AC) emits -0.10 kg of CO2e. In-sink grinding (ISG) via a food-waste disposer and flushing for management with other sewage at a wastewater treatment plant emits 0.10 kg of CO2e. Harmonization reduced climate emissions versus nonharmonized averages. Harmonized energy impacts range from -0.32 MJ for ISG to 1.14 MJ for AC. AD at 0.27 MJ and LFGTE at 0.40 MJ fall in between. Rankings based on soil studies show AC first for carbon storage and water conservation, with AD second. AD first for fertilizer replacement, with AC second, and AC and AD tied for first for plant yield increase. ISG ranks third and LFGTE fourth on all four soil-quality and productivity indicators. Suggestions for further research include developing soil benefits measurement methods and resolving inconsistencies in the results between life-cycle assessments and soil science studies.

Green House Gases(GHG) emissions from the ornamental plant nursery industry: a Life Cycle Assessment(LCA) approach in a nursery district in central Italy

The ornamental plant nursery industry is the most important economic resource of Pistoia, a city situated in Tuscany in the center-north of Italy. The production of plants offers many benefits in the social and environmental spheres: it generates employment, improves the landscape and gives a contribution to carbon dioxide accumulation. On the other hand, nurseries are considered intensive agricultural systems, responsible for soil erosion, waste production, and soil, air and water pollution. The research presented in this paper aimed to quantify the environmental impact, in terms of GHG (Green House Gases) emissions of different nursery typologies (in-pot and in-field grown plants) and productions (small, medium and large size plants). For this reason, a LCA (Life Cycle Assessment) approach was carried out in seven different nurseries on eleven production lines. GWP (Global Warming Potential) was the impact category chosen for this analysis, and the square meter was used as functional unit to represent the differences between nursery and plant typologies, although data for “product” unit are shown as well. Results show that in-pot systems, with an emissions range of 7.444–26.489 kg of CO2-e are much more impacting than in-field grown production processes (0.607–1.013 kg of CO2-e). Such great differences are mainly due to the peat used in substrate mixes and the plastic used for pots, indeed these are the most important sources of GHG emissions, and are widely used in in-pot production, while they are not present in in-field processes. The final part of the paper is devoted to a comparison of results obtained in Pistoia and other research conducted in the U.S. in order to evaluate the differences in total CO2 emissions between different plant production processes and to offer some recommendations about how to reduce GHG emissions in ornamental plant nurseries.

A life cycle assessment of annual, N fertilised perennial and non-N fertilised perennial pastures, South-Western Australia

This research aims to assess the emissions of greenhouse gases (GHGs) from one kilogram of live weight cattle production from annual pastures, nitrogen (N) fertilised perennial pastures and non-N fertilised perennial pastures in Western Australia for different farming practices. Using streamlined life cycle assessment (SLCA) methodology, it was estimated that approximately 14.30 kg, 12.09 kg and 11.0 kg of CO2-e of GHG emissions will be emitted from the production of one kilogram of live weight cattle from annual, non-N fertilised and N fertilised perennial pastures respectively. Enteric emissions account for a significant portion of GHG emissions (85% from annual pasture and around 95% from perennial pastures). Live weight yields from annual pasture emit more GHG emissions than do N fertilised and non-N fertilised perennial pastures. Although the inclusion of liming produces additional GHG emissions, the increase in productivity associated with these activities can actually offset GHG emissions when considered on a per kilogram basis.

Biosolid stockpiles are a significant point source for greenhouse gas emissions

The wastewater treatment process generates large amounts of sewage sludge that are dried and then often stored in biosolid stockpiles in treatment plants. Because the biosolids are rich in decomposable organic matter they could be a significant source for greenhouse gas (GHG) emissions, yet there are no direct measurements of GHG from stockpiles. We therefore measured the direct emissions of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) on a monthly basis from three different age classes of biosolid stockpiles at the Western Treatment Plant (WTP), Melbourne, Australia, from December 2009 to November 2011 using manual static chambers. All biosolid stockpiles were a significant point source for CH4 and N2O emissions. The youngest biosolids (<1 year old) had the greatest CH4 and N2O emissions of 60.2 kg of CO2-e per Mg of biosolid per year. Stockpiles that were between 1 and 3 years old emitted less overall GHG (∼29 kg CO2-e Mg−1 yr−1) and the oldest stockpiles emitted the least GHG (∼10 kg CO2-e Mg−1 yr−1). Methane emissions were negligible in all stockpiles but the relative contribution of N2O and CO2 changed with stockpile age. The youngest stockpile emitted two thirds of the GHG emission as N2O, while the 1–3 year old stockpile emitted an equal amount of N2O and CO2 and in the oldest stockpile CO2 emissions dominated. We did not detect any seasonal variability of GHG emissions and did not observe a correlation between GHG flux and environmental variables such as biosolid temperature, moisture content or nitrate and ammonium concentration. We also modeled CH4 emissions based on a first order decay model and the model based estimated annual CH4 emissions were higher as compared to the direct field based estimated annual CH4 emissions. Our results indicate that labile organic material in stockpiles is decomposed over time and that nitrogen decomposition processes lead to significant N2O emissions. Carbon decomposition favors CO2 over CH4 production probably because of aerobic stockpile conditions or CH4 oxidation in the outer stockpile layers. Although the GHG emission rate decreased with biosolid age, managers of biosolid stockpiles should assess alternate storage or uses for biosolids to avoid nutrient losses and GHG emissions.

The greenhouse emissions footprint of free-range eggs

Eggs are an increasingly significant source of protein for human consumption, and the global poultry industry is the single fastest-growing livestock sector. In the context of international concern for food security and feeding an increasingly affluent human population, the contribution to global greenhouse-gas (GHG) emissions from animal protein production is of critical interest. We calculated the GHG emissions footprint for the fastest-growing sector of the UK egg market: free-range production in small commercial units on mixed farms. Emissions are calculated to current Intergovernmental Panel on Climate Change and UK standards (PAS2050): including direct, indirect, and embodied emissions from cradle to farm gate compatible with a full product life-cycle assessment. We present a methodology for the allocation of emissions between ruminant and poultry enterprises on mixed farms. Greenhouse gas emissions averaged a global warming potential of 2.2 kg of CO2e/dozen eggs, or 1.6 kg of CO2equivalent (e)/kg (assuming average egg weight of 60 g). One kilogram of protein from free-range eggs produces 0.2 kg of CO2e, lower than the emissions from white or red meat (based on both kg of meat and kg of protein). Of these emissions, 63% represent embodied carbon in poultry feed. A detailed GHG emissions footprint represents a baseline for comparison with other egg production systems and sources of protein for human consumption. Eggs represent a relatively low-carbon supply of animal protein, but their production is heavily dependent on cereals and soy, with associated high emissions from industrial nitrogen production, land-use change, and transport. Alternative sources of digestible protein for poultry diets are available, may be produced from waste processing, and would be an effective tool for reducing the industry's GHG emissions and dependence on imported raw materials.

Carbon Footprint of Beef Cattle

The carbon footprint of beef cattle is presented for Canada, The United States, The European Union, Australia and Brazil. The values ranged between 8 and 22 kg CO2e per kg of live weight (LW) depending on the type of farming system, the location, the year, the type of management practices, the allocation, as well as the boundaries of the study. Substantial reductions have been observed for most of these countries in the last thirty years. For instance, in Canada the mean carbon footprint of beef cattle at the exit gate of the farm decreased from 18.2 kg CO2e per kg LW in 1981 to 9.5 kg CO2e per kg LW in 2006 mainly because of improved genetics, better diets, and more sustainable land management practices. Cattle production results in products other than meat, such as hides, offal and products for rendering plants; hence the environmental burden must be distributed between these useful products. In order to do this, the cattle carbon footprint needs to be reported in kg of CO2e per kg of product. For example, in Canada in 2006, on a mass basis, the carbon footprint of cattle by-products at the exit gate of the slaughterhouse was 12.9 kg CO2e per kg of product. Based on an economic allocation, the carbon footprints of meat (primal cuts), hide, offal and fat, bones and other products for rendering were 19.6, 12.3, 7 and 2 kg CO2e per kg of product, respectively.

High-yield maize with large net energy yield and small global warming intensity

Addressing concerns about future food supply and climate change requires management practices that maximize productivity per unit of arable land while reducing negative environmental impact. On-farm data were evaluated to assess energy balance and greenhouse gas (GHG) emissions of irrigated maize in Nebraska that received large nitrogen (N) fertilizer (183 kg of N · ha(-1)) and irrigation water inputs (272 mm or 2,720 m(3) ha(-1)). Although energy inputs (30 GJ · ha(-1)) were larger than those reported for US maize systems in previous studies, irrigated maize in central Nebraska achieved higher grain and net energy yields (13.2 Mg · ha(-1) and 159 GJ · ha(-1), respectively) and lower GHG-emission intensity (231 kg of CO(2)e · Mg(-1) of grain). Greater input-use efficiencies, especially for N fertilizer, were responsible for better performance of these irrigated systems, compared with much lower-yielding, mostly rainfed maize systems in previous studies. Large variation in energy inputs and GHG emissions across irrigated fields in the present study resulted from differences in applied irrigation water amount and imbalances between applied N inputs and crop N demand, indicating potential to further improve environmental performance through better management of these inputs. Observed variation in N-use efficiency, at any level of applied N inputs, suggests that an N-balance approach may be more appropriate for estimating soil N(2)O emissions than the Intergovernmental Panel on Climate Change approach based on a fixed proportion of applied N. Negative correlation between GHG-emission intensity and net energy yield supports the proposition that achieving high yields, large positive energy balance, and low GHG emissions in intensive cropping systems are not conflicting goals.

Sources of uncertainty in the IPCC Tier 2 Canadian livestock model

SUMMARYEstimates of uncertainties are essential when comparing the greenhouse gas (GHG) emissions from a variety of sources. Monte Carlo Simulation (MCS) was applied to estimate the uncertainties in methane emissions and the methane emission intensities from livestock in Canada, calculated using the Intergovernmental Panel on Climate Change (IPCC) methodology. National methane emissions from enteric fermentation and manure management in 2008 were 21·2 and 4·3 Teragram CO2 equivalents (Tg CO2e) with uncertainties of 38 and 73%, respectively. The methane emission intensities (kg of CO2e per kg of live animal weight) were 5·9, 0·9 and 4·9 from Canadian beef, swine and lamb, respectively, with overall uncertainties of 44, 99 and 101%, defined as the 95% confidence interval relative to the mean. A sensitivity analysis demonstrated that IPCC default parameters such as the methane conversion rate (Ym), the coefficient for calculating net energy for maintenance (Cfi) and the methane conversion factor (MCF) were the greatest sources of uncertainty. Canadian agricultural methane emissions are usually calculated by province and by animal subcategories. However, the IPCC default parameters can be assumed to be correlated among regions and animal subcategories; therefore values are assigned at the national scale for the main cattle categories (dairy and non-dairy cattle). When it was assumed that these parameters were uncorrelated at the regional scale, the overall uncertainties were reduced to 20 and 48% for enteric fermentation and manure management, respectively, and assuming that parameters were uncorrelated at the animal subcategory scale reduced uncertainties to 13 and 41% for enteric fermentation and manure management, respectively. When the uncertainty is assigned at the most disaggregated level, even doubling the uncertainty of key parameters such as Ym and Cfi, only increased the national uncertainties to 22 and 52% for enteric fermentation and manure management, respectively. The current analysis demonstrated the importance of obtaining parameters specific to regions and animal subcategories in order to estimate GHG emissions more accurately and to reduce the uncertainties in agricultural GHG inventories. It also showed that assumptions made in the calculation of uncertainties can have a large influence on the uncertainty estimates.

Potential for improving the carbon footprint of butter and blend products

To reduce the environmental impact of a product efficiently, it is crucial to consider the entire value chain of the product; that is, to apply life cycle thinking, to avoid suboptimization and identify the areas where the largest potential improvements can be made. This study analyzed the carbon footprint (CF) of butter and dairy blend products, with the focus on fat content and size and type of packaging (including product waste at the consumer level). The products analyzed were butter with 80% fat in 250-g wrap, 250-g tub, and 10-g mini tub, and blends with 80% and 60% fat in 250-g tubs. Life cycle assessment was used to account for all greenhouse gas emissions from cow to consumer. A critical aspect when calculating the CF is how emissions are allocated between different products. Here, allocation of raw milk between products was based on a weighted fat and protein content (1:1.7), based on the price paid for raw milk to dairy farmers. The CF (expressed as carbon dioxide equivalents, CO2e) for 1kg of butter or blend (assuming no product waste at consumer) ranged from 5.2kg (blend with 60% fat content) to 9.3kg of CO2e (butter in 250-g tub). When including product waste at the consumer level, the CF ranged from 5.5kg of CO2e (blend with 60% fat content) to 14.7kg of CO2e (butter in mini tub). Fat content and the proportion of vegetable oil in products had the greatest effect on CF of the products, with lower fat content and a higher proportion of vegetable oil resulting in lower CF. Hence, if the same functionality as butter could be retained while shifting to lower fat and higher proportions of vegetable oil, the CF of the product would be decreased. Size and type of packaging were less important, but it is crucial to have the correct size and type of packaging to avoid product losses at the consumer. The greatest share of greenhouse gas emissions associated with butter production occurred at the farm level; thus, minimizing product losses in the whole value chain—from cow to consumer—is essential for efficient production.

Life cycle assessment modelling of complex agricultural systems with multiple food and fibre co-products

Most agricultural products are produced on farms where there is a mix of activities, resulting in a range of co-products. This raises the issue of how best to model these complex production systems for Life Cycle Assessment, especially where there are benefits imparted by one activity in the mixed farming system to another. On the mixed farm studied, there were significant two-way reference flows (representing 288 t CO2-e/year or 10% of the total farm emissions) between activities producing distinct products (wool, meat, grain) and these were modelled using system expansion. Cropping and sheep activities were modelled as separate sub-processes in the farming system, with unique inputs and outputs identified for each. Co-production from the sheep activity was modelling using allocation, comparing biophysical and economic relationships. Using an economic allocation resulted in different estimates of global warming impact for sheep co-products, with figures varying by 7–52%. When compared to biophysical allocation, economic allocation shifted the environmental burden to the higher value co-products and away from the high resource use products. Using economic allocation, for every kilogram of wool produced there was an estimated 28.7 kg of CO2-e emitted. Amongst the live animal products, the stud rams had the highest estimated carbon footprint (719 kg CO2-e/ram). Amongst the crops, estimates of emissions for the cereal grains averaged 202 kg CO2-e/tonne grain, canola 222 kg CO2-e/tonne and lupins 510 kg CO2-e/tonne, when modelled to include the benefits of the mixed farming system.

An Epizootic Fever Among Horses in South Australia

This study aims to assess the deployment potential of hybrid concentrated solar biomass (HCSB) plants for dispatchable renewable electricity generation in New South Wales (NSW), Australia. We present an approach for identifying the most suitable locations for siting new plants. HCSB plants generate steam using a biomass boiler and a concentrated solar power (CSP) system and utilise a shared steam turbine for power generation. The total power generation opportunity was estimated based on available resources. This was achieved by mapping solid biomass (bagasse, stubble and forestry residues) and solar resources (direct normal irradiation) in proximity to zone substations with new grid connection capacity. The total installed capacity of HCSB plants at suitable grid connection locations was calculated to be 874 MWe at a cost of about AU$ 6.3 billion. We also estimated the CO2-e emission abatement potential to be about 6 billion kg of CO2-e per year. The Riverina region was identified to be the most prospective region for HCSB plants in NSW owing to excellent biomass and solar resources and 25 suitable grid connection points. These findings underline NSW’s excellent deployment potential for HCSB plants, a technology that can utilize the vast and currently under-exploited biomass residues and solar resources for dispatchable renewable electricity generation.