Greenhouse Gas Emissions Profile Research Articles

Greenhouse Gas Emissions Accounting of Urban Residential Consumption: A Household Survey Based Approach

Devising policies for a low carbon city requires a careful understanding of the characteristics of urban residential lifestyle and consumption. The production-based accounting approach based on top-down statistical data has a limited ability to reflect the total greenhouse gas (GHG) emissions from residential consumption. In this paper, we present a survey-based GHG emissions accounting methodology for urban residential consumption, and apply it in Xiamen City, a rapidly urbanizing coastal city in southeast China. Based on this, the main influencing factors determining residential GHG emissions at the household and community scale are identified, and the typical profiles of low, medium and high GHG emission households and communities are identified. Up to 70% of household GHG emissions are from regional and national activities that support household consumption including the supply of energy and building materials, while 17% are from urban level basic services and supplies such as sewage treatment and solid waste management, and only 13% are direct emissions from household consumption. Housing area and household size are the two main factors determining GHG emissions from residential consumption at the household scale, while average housing area and building height were the main factors at the community scale. Our results show a large disparity in GHG emissions profiles among different households, with high GHG emissions households emitting about five times more than low GHG emissions households. Emissions from high GHG emissions communities are about twice as high as from low GHG emissions communities. Our findings can contribute to better tailored and targeted policies aimed at reducing household GHG emissions, and developing low GHG emissions residential communities in China.

Microalgal biomass production pathways: evaluation of life cycle environmental impacts.

BackgroundMicroalgae are touted as an attractive alternative to traditional forms of biomass for biofuel production, due to high productivity, ability to be cultivated on marginal lands, and potential to utilize carbon dioxide (CO2) from industrial flue gas. This work examines the fossil energy return on investment (EROIfossil), greenhouse gas (GHG) emissions, and direct Water Demands (WD) of producing dried algal biomass through the cultivation of microalgae in Open Raceway Ponds (ORP) for 21 geographic locations in the contiguous United States (U.S.). For each location, comprehensive life cycle assessment (LCA) is performed for multiple microalgal biomass production pathways, consisting of a combination of cultivation and harvesting options.ResultsResults indicate that the EROIfossil for microalgae biomass vary from 0.38 to 1.08 with life cycle GHG emissions of −46.2 to 48.9 (g CO2 eq/MJ-biomass) and direct WDs of 20.8 to 38.8 (Liters/MJ-biomass) over the range of scenarios analyzed. Further anaylsis reveals that the EROIfossil for production pathways is relatively location invariant, and that algae’s life cycle energy balance and GHG impacts are highly dependent on cultivation and harvesting parameters. Contrarily, algae’s direct water demands were found to be highly sensitive to geographic location, and thus may be a constraining factor in sustainable algal-derived biofuel production. Additionally, scenarios with promising EROIfossil and GHG emissions profiles are plagued with high technological uncertainty.ConclusionsGiven the high variability in microalgae’s energy and environmental performance, careful evaluation of the algae-to-fuel supply chain is necessary to ensure the long-term sustainability of emerging algal biofuel systems. Alternative production scenarios and technologies may have the potential to reduce the critical demands of biomass production, and should be considered to make algae a viable and more efficient biofuel alternative.

Carbon Accounting for Woody Biomass from Massachusetts (USA) Managed Forests: A Framework for Determining the Temporal Impacts of Wood Biomass Energy on Atmospheric Greenhouse Gas Levels

Policies based on assumed carbon neutrality fail to address the timing and magnitude of the net greenhouse gas (GHG) changes from using wood for energy. We present a “debt-then-dividend” framework for evaluating the temporal GHG impacts of burning wood for energy. We also present a case study conducted in Massachusetts, USA to demonstrate the framework. Four key inputs are required to calculate the specific shape of the debt-then-dividend curve for a given region or individual biomass facility. First, the biomass feedstock source: the GHG implications of feedstocks differ depending on what would have happened to the material in the absence of biomass energy generation. Second, the form of energy generated: energy technologies have different generation efficiencies and thus different life cycle GHG emissions profiles. Third, the fossil fuel displaced: coal, oil, and natural gas each have different emissions per unit of energy produced. Fourth, the management of the forest: forest management decisions affect recovery rates of carbon from the atmosphere. This framework has broad application for informing the development of renewable energy and climate policies. Most importantly, this debt-then-dividend framework explicitly recognizes that GHG benefits of wood biomass energy will be specific to the forest and technology context of the region or biomass energy projects.

Greenhouse gas emissions profile for 1 kg of wool produced in the Yass Region, New South Wales: A Life Cycle Assessment approach

The use of Life Cycle Assessment (LCA) to determine environmental impacts of agricultural production, as well as production by other industry sectors has increased. LCA provides an internationally accepted method to underpin labelling and marketing of agricultural products, a valuable tool to compare emissions reduction strategies and a means to identify perverse policy outcomes. A single-issue LCA focussing on greenhouse gas emissions was conducted to determine the emissions profile and carbon footprint of 19-micron wool produced in the Yass Region on the Southern Tablelands of New South Wales. Greenhouse gas emissions (in carbon dioxide equivalents; CO2-e) from the production of all enterprise inputs and from the production of wool on-farm were included. Total emissions were found to be 24.9 kg CO2-e per kg of greasy wool at the farm gate, based on a 4941 breeding ewe enterprise on 1000 ha, with a total greasy wool yield of 65.32 t per annum. The co-products included 174 t sheep meat as liveweight from wethers and cull ewes plus 978 maiden ewes sold off-farm as replacement stock. Total emissions from all products grown on 1000 ha were 2899 t CO2-e per annum. The relative contribution of greenhouse gas emissions from different components of the production system was determined. Direct emission of methane on-farm (86% of total) was the dominant emission, followed by nitrous oxide emitted from animal wastes directly (5%) and indirectly (5%), and decomposition of pasture residue (1%). Only 2% of total emissions were embodied in farm inputs, including fertiliser. The emissions profile varied according to calculation method and assumptions. Enteric methane production was calculated using five recognised methods and results were found to vary by 27%. This study also showed that calculated emissions for wool production changed substantially, under an economic allocation method, by changing the enterprise emphasis from wool to meat production (41% decrease) and by changing wool price (29% variability), fibre diameter (23% variability) and fleece weight (11% variability). This paper provides data specific to the Yass Region and addresses broader methodological issues, to ensure that future livestock emissions calculations are robust.

Greenhouse gas emissions profile for 1 tonne of wheat produced in Central Zone (East) New South Wales: a life cycle assessment approach

Life Cycle Assessment (LCA) has become an increasingly common approach across different industries, including agriculture, for environmental impact assessment. A single-issue LCA focusing on greenhouse gas emissions was conducted to determine the emissions profile and total carbon footprint of wheat produced in the Central Zone (East) of New South Wales. Greenhouse gas emissions (in carbon dioxide equivalents; CO2-e) from all stages of the production process, both pre-farm and on-farm, were included. Total emissions were found to be 200 kg CO2-e per t of wheat at the farm gate, based on a 3.5 t/ha grain yield. The relative contribution of greenhouse gas emissions from different components of the production system was determined, with most emissions (37%) coming from pre-farm production and transport of fertiliser (30%) and lime (7%) and from the nitrous oxide (N2O) emitted from the nitrogenous fertiliser applied to the crop (26%). Other important emissions included the CO2 emissions from the use of fertiliser and lime (15%) and the production, transport and use of diesel (16%). The relative importance of other minor emissions is also discussed. For a higher yielding crop (5.0 t/ha), total emissions were found to be 150 kg CO2-e per t of wheat. This paper considers the effect of different management scenarios on the emissions profile and the effect of adopting a N2O emissions factor, which is based on current New South Wales field research, rather than the current Australian National Greenhouse Accounts National Inventory Report default value. This LCA provides a template from which comparative farming systems LCA can be developed and provides data for the Australian Life Cycle Inventory.

Greenhouse gas emission profiles of European livestock sectors

There are increasing concerns about the ecological footprint of global animal production. Expanding livestock sectors worldwide contribute to expansion of agricultural land and associated deforestation, emissions of greenhouse gases (GHG), eutrophication of surface waters and nutrient imbalances. Farm based studies indicate that there are large differences among farms in animal productivity and environmental performance. Here, we report on regional variations in dairy, beef, pork, poultry and egg production, and related GHG emissions in the 27 Member States of the European Union (EU-27), based on 2003–2005 data. Analyses were made with the MITERRA-Europe model which calculates annual nutrient flows and GHG emissions from agriculture in the EU-27. Main input data were derived from CAPRI (i.e., crop areas, livestock distribution, feed inputs), GAINS (i.e., animal numbers, excretion factors, NH3 emission factors), FAO statistics (i.e., crop yields, fertilizer consumption, animal production) and IPCC (i.e., CH4, N2O, CO2 emission factors). Sources of GHG emissions included were enteric fermentation, manure management, direct and indirect N2O soil emissions, cultivation of organic soils, liming, fossil fuel use and fertilizer production. The dairy sector had the highest GHG emission in the EU-27, with annual emission of 195TgCO2-eq, followed by the beef sector with 192TgCO2-eq. Enteric fermentation was the main source of GHG emissions in the European livestock sector (36%) followed by N2O soil emissions (28%). On a per kg product basis, beef had by far the highest GHG emission with 22.6kgCO2-eq/kg, milk had an emission of 1.3kgCO2-eq/kg, pork 3.5kgCO2-eq/kg, poultry 1.6kgCO2-eq/kg, and eggs 1.7kgCO2-eq/kg. However large variations in GHG emissions per unit product exist among EU countries, which are due to differences in animal production systems, feed types and nutrient use efficiencies. There are, however, substantial uncertainties in the base data and applied methodology such as assumptions surrounding allocation of feeds to livestock species. Our results provide insight into differences in GHG sources and emissions among animal production sectors for the various regions of Europe.This article is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors; K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.

Impact of Driving Cycles on Greenhouse Gas Emissions and Fuel Economy for SI Car Real World Driving

The transport sector is one of the major contributors to greenhouse gas emissions. This study investigated three greenhouse gases emitted from road transport: CO2, N2O and CH4 emissions as a function of engine warm up and driving cycles. Five different urban driving cycles were developed and used including free flow driving and congested driving. An in-vehicle FTIR (Fourier Transform Inferred) emission measurement system was installed on a EURO2 emission compliant SI (Spark Ignition) car for emissions measurement at a rate of 0.5 HZ under real world urban driving conditions. This emission measurement system was calibrated on a standard CVS (Constant Volume Sampling) measurement system and showed excellent agreement on CO2 measurement with CVS results. The N2O and CH4 measurement was calibrated using calibration gas in lab. A MAX710 real time in-vehicle fuel consumption measurement system was installed in the test vehicle and real time fuel consumption was then obtained. The temperatures across the TWC (Three Way Catalyst) and engine out exhaust gas lambda were measured. The GHG (greenhouse gas) mass emissions and consequent GWP (Global Warming Potential) for different urban diving conditions were analyzed and presented. The results provided a better understanding of traffic related greenhouse gas emission profile in urban area and will contribute to the control of climate change.

An Investigation of Synthetic Fuel Production via Chemical Looping

Producing liquid hydrocarbon fuels with a reduced greenhouse gas emissions profile would ease the transition to a carbon-neutral energy sector with the transportation industry being the immediate beneficiary followed by the power industry. Revolutionary solutions in transportation, such as electricity and hydrogen, depend on the deployment of carbon capture and storage technologies and/or renewable energy systems. Additionally, high oil prices may increase the development of unconventional sources, such as tar sands, that have a higher emissions profile. One process that is gaining interest is a system for producing reduced carbon fuels though chemical looping technologies. An investigation of the implications of such a process using methane and carbon dioxide that is reformed to yield methanol has been done. An important aspect of the investigation is the use of off-the-shelf technologies to achieve the results. The ability of the process to yield reduced emissions fuels depends on the source for the feed and process heat. For the range of conditions considered, the emissions profile of methanol produced in this method varies from 0.475 to 1.645 moles carbon dioxide per mole methanol. The upper bound can be lowered to 0.750 by applying CCS and/ or using nonfossil heat sources for the reforming. The process provides an initial pathway to incorporate CO2 into fuels independent of electrolytic hydrogen or developments in other sectors of the economy.

Using the OVERSEER nutrient budget model to estimate on-farm greenhouse gas emissions

The OVERSEER nutrient budget model is a farm-scale nutrient reporting and greenhouse gas (GHG) emission accounting tool used extensively throughout New Zealand (NZ) by farmers, farm consultants and fertiliser representatives. The model is increasingly being used as a tool for implementing regional council resource management requirements to limit nitrogen (N) and phosphorus losses to waterways. NZ’s main dairy company, Fonterra, also requires dairy farmers to have a nutrient budget as part of the national Clean Streams Accord. This means that a high proportion of NZ farmers can obtain reports of their on-farm GHG emission profile. The GHG emission model is based on models and algorithms used for the NZ GHG national inventory, modified to include a wide range of on-farm management practices. The model estimates methane, nitrous oxide and carbon dioxide (CO2) emissions, and presents the results as CO2 equivalents. This paper describes the model and the benefits of combining nutrients budgets and GHG emissions into a single model. It also demonstrates the effects of management practices on a range of outputs, including N leaching and GHG emissions.

Multi-Stage: A Rule-Based Evolution of Future Commitments under the Climate Change Convention

This article presents the regional emission targets corresponding to different climate regimes for differentiating commitments beyond 2012 on the basis of the Multi-Stage approach. This approach assumes a gradual increase in the number of Parties involved and their level of commitment according to participation and differentiation rules. The analysis focuses on two global greenhouse gas emission profiles resulting in CO2-equivalent concentrations stabilising at 550 and 650 ppmv in 2100 and 2150, respectively. Three Multi-Stage cases have been developed in order to assess different types of thresholds. These share three consecutive stages representing different commitments: stage 1 – no quantitative commitments; stage 2 – emission–limitation targets and stage 3 – emission reduction targets. The analysis shows that by 2025 all three cases result in emission reduction objectives for all Annex I regions of at least 30–55% below their 1990 levels for 550 ppmv, whereas for 650 ppmv target they range from 0 to 20%. Furthermore, early participation is required of the major non-Annex I regions through emission limitation targets i.e. before 2025 and 2050 for the 550 and 650 ppmv targets, respectively. The first participation threshold for adopting emission–limitation targets on the basis of a capability–responsibility index (as introduced here) can provide for a balanced and timely participation of non-Annex I regions. Major strengths and weaknesses of the climate regimes are discussed and important obstacles and pre-conditions for their feasibility and acceptability are highlighted.

Constructing a greenhouse gas emissions inventory using energy balances: the case of South Africa for 1998

This paper discusses the procedures and results of constructing a greenhouse gas (GHG) emissions inventory for South Africa, using the official national energy balance for 1998. In doing so, the paper offers a snapshot of the South African energy supply and demand profile and encompassing greenhouse gas emissions profiles, disaggregated into 40 economic sectors, for the reference year. For convenience, energy supply and use are reported in both native units and terra joule (TJ), while emissions are expressed in carbon dioxide equivalents and reported in giga-gram (Gg). While carbon dioxide makes an overwhelming contribution to global anthropogenic GHG emissions, the inclusion of methane and nitrous oxide offers considerable richness to the analysis of climate change policies. Applying the energy balances, it was possible to compile a comprehensive emissions inventory using a consistent methodology across all sectors of the economy. The inventory allows the economic analyst to model various economic policies either with fuel as an input to production, or the consumption of fuel or the emissions generated during combustion, as a base of the analysis. The dominant role of coal as a source of energy, with a total primary energy supply (TPES) of 3.3 million TJ or 70 per cent of the total TPES, is clearly shown. Emissions from coal combustion (263 783 Gg of carbon dioxide equivalents or 74.7 per cent of total emissions) are henceforth the largest contributor to total emissions, estimated to be 352 932 Gg carbon dioxide equivalents.

OVERSEER® nutrient budgets - moving towards on-farm resource accounting

Nutrient budgets are useful tools for assessing the sustainability of nutrient flows within a farm and for highlighting potential negat ive environmental impacts of nutrient use. The OVERSEER® nutr ient budgets program is a decision support model to help users develop nutrient budgets. This paper outlines an upgrade to the OVERSEER® nutrient budgets program, with improvements in nitrogen (N), phosphorus (P), potassium (K) and sulphur (S), and addition of calcium (Ca), magnesium (Mg), sodium (Na) and hydrogen (potential acidity). Energy use and greenhouse gas emission profiles from farms have been included in the model. Using 'typical farm' and simulation studies, the paper then outlines how nutrient budget can be used to improve farm nutrient management. Keywords: acidity, calcium, energy, green house gas, inventory, lime, magnesium, maintenance fertiliser, nitrogen, nutr ient budgeting, phosphorus, potassium, resource accounting, sodium, sulphur

Assessment of mitigation options for the energy system in Bulgaria

The Bulgarian greenhouse gas (GHG) emission profile reveals the energy sector as the most significant emission source and also as an area where great potential for GHG emissions reduction exists. Mitigation options in energy supply were selected considering the potential of fossil fuel substitution and new energy technology implementation in the context of the existing structure of energy system and projects for mid- and long-term development. Basically three modules of ENPEP were used: BALANCE — to calculate the energy flows and energy cost from primary fuel resources and fuel import to energy end-use, IMPACT — to calculate GHG emissions, and ELECTRIC — to project the electric system long-term development. Different mitigation measures combined in four scenarios were developed. The integrated mitigation scenario incorporated a mix of mitigation measures in the energy demand and supply. Implementation of CO 2 mitigation measures both in energy demand and energy supply would reduce the 2020 emission level by 34.3 Tg (29.1%), and by 544.2 Tg (21.7%) for the entire study period 2000 – 2020, compared to the baseline scenario.