Carbon Equivalent Emissions Research Articles

Carbon Footprint of Public Transportation – A Case Study of Religious Tourism to Shri Mata Vaishano Devi Shrine in Katra, Jammu and Kashmir, India

The rates of increment in G h Gs concentrations in the atmosphere are extraordinarily high, far exceeding their natural sequestration rates. Transportation accounts to 19% of the global energy use and 23% of all the C o 2 emissions globally, a bout 75% of these emissions come from cars and trucks. i n i ndia, transportation sector consumes about 17% of total energy and produces 60% of G h G emissions, estimated at around 261 Tg of C o 2 , of which 94.5% is contributed by road transport. Travel and tourism, one of the largest industries in the world is a significant contributor to greenhouse gas emissions. Religious tourism in particular, is an important cultural and traditional heritage of i ndia. This paper is a case study to estimate the individual carbon footprints of pilgrims travelling s hri m ata Vaishano Devi s hrine in k atra, Jammu and k ashmir. The analysis considers individual emissions from different modes of transportation viz. train, bus, taxi/auto-rickshaw and air travel using equivalent carbon emission factors.

Technoeconomics and Sustainability of Renewable Methanol and Ammonia Productions Using Wind Power-based Hydrogen

This study analyzes and compares the economics and sustainability aspects of two hydrogenation processes for producing renewable methanol and ammonia by using wind-power based electrolytic hydrogen. Carbon dioxide from an ethanol plant is used for producing methanol, while the nitrogen is supplied by an Air Separation Unit (ASU) for producing ammonia. The capacities are 99.96 mt/day methanol and 1202.55 mt/day anhydrous ammonia. The methanol plant requires 138.37 mt CO2/day and 19.08 mt H2/day. The ammonia is synthesized by using 217.72 mt H2/day and 1009.15 mt N2/day. The production costs and the carbon equivalent emissions (CO2e) associated with the methanol and ammonia processes, electrolytic hydrogen production, carbon capture and compression, and ASU are estimated. The integral facilities of both the methanol and ammonia productions are evaluated by introducing a multi-criteria decision matrix containing economics and sustainability metrics. Discounted cash flow diagrams are established to estimate the economic constraints, unit product costs, and unit costs of hydrogen. The hydrogen cost is the largest contributor to the economics of the plants. For the methanol, the values of emissions are -0.85 kg CO2e/kg methanol as a chemical feedstock and +0.53 kg CO2e/kg methanol as a fuel with complete combustion. For the ammonia, the value of emission is around 0.97 kg CO2e/kg ammonia. The electrolytic hydrogen from wind power helps reduce the emissions; however, the cost of hydrogen at the current level adversely affects the feasibility of the plants. A multi-criteria decision matrix shows that renewable methanol and ammonia with wind power-based hydrogen may be feasible compared with the nonrenewable ones and the renewable methanol may be more favorable than the ammonia.

Organic Manures and Crop Residues as Fertilizer Substitutes: Impact on Nitrous Oxide Emission, Plant Growth and Grain Yield in Pre-Monsoon Rice Cropping System

It has been previously argued that application of organic residues added in soils has a great impact on soil quality, grain productivity as well as greenhouse gas emissions. Substitution of chemical fertilizers has become a common practice in agricultural systems which consequently affect the greenhouse gas emissions from agricultural fields. To observe the effects of organic manures and crop residues amendments, five fertilizer treatments including conventional inorganic nitrogen fertilizer—NPK, cow manure, rice straw, poultry manure and sugarcane bagasse were applied in the field for two consecutive pre-monsoon rice seasons. Addition of rice straw, poultry manure and sugarcane bagasse decreased the cumulative N2O emissions by 14% and 31%, and by 1% and 7% and 5% and 3% in 2012 and 2013 respectively when compared with conventional fertilizer treatment (NPK) in both the seasons. Yield differences were not significant (p > 0.005) amongst the treatments, however, a slight increase was observed due to rice straw amendment over control. Soil organic carbon decreased by 11% - 17% under the application of organic residues which might have contributed to lower N2O emissions from the plots. Results of carbon equivalent emission (CEE) and carbon efficiency ratio (CER) indicated that incorporation of rice straw during pre-monsoon rice season had the potential to reduce the N2O emissions and yield scaled emissions of rice production at lower level than the conventional farmers’ practice of using chemical fertilizers (NPK).

Impact of Nitrogen Fertilizer Application on Nitrous Oxide Emission in Oil Palm Plantation

This study investigates the impact of N-fertilizer application on the emission of nitrous oxide (N2O) in oil palm plantations. The soil sampling was undertaken at three different oil palm plantations of different land use, i.e. transformed land use (large and small-scale) and a logged-over forest. The soil samples were analysed for N, P and K contents and soil organic carbon. It was found that despite different amount of N-fertilizer applied at the plantations (in the range of 99-155kg N/ha), immature palm development seems to release relatively higher amount of N2O compared to mature stage. However, further estimation of carbon equivalent emission (CO2-eq) would be a more useful means for estimating the impact of N-fertilizer on greenhouse gas emission.

Selection of pallet management strategies based on carbon emissions impact

This work describes the lifecycle of wood pallets as they move through the supply chain and compares the environmental impacts of the three predominant pallet management strategies: single-use expendable, reusable buy/sell, and reusable leased pool. The pallet lifecycle is characterized in five phases: raw material sourcing, manufacturing, transportation and use, refurbishing, and end of life (EOL) disposal. Given that the useful life of a pallet and the environmental impacts that are generated during each phase of the pallet lifecycle vary, carbon equivalent emission functions are developed for each of the three pallet management strategies. The loading and handling conditions that pallets are subjected to as they move through the supply chain are considered as these greatly affect their useful life, and therefore have a significant impact on carbon emissions. In addition, an optimization model is developed to explore the effectiveness of blended or mixed pallet management strategies in minimizing carbon equivalent emissions under various loading, handling, and EOL scenarios. The findings suggest that no single pallet management approach is universally preferred in terms of minimizing carbon equivalent emissions. Under different handling, loading, and EOL conditions and different distribution distance requirements, any of the three available pallet management strategies may be preferred, or a combination of strategies may be required to minimize carbon equivalent emissions. This work can support decision making by logisticians and managers as they seek to minimize the carbon footprint of their operations by adopting practices and adapting the models to their specific conditions.

The Carbon Footprint of Games Distribution

SummaryThis research investigates the carbon footprint of the lifecycle of console games, using the example of PlayStation®3 distribution in the UK. We estimate total carbon equivalent emissions for an average 8.8‐gigabyte (GB) game based on data for 2010. The bulk of emissions are accounted for by game play, followed by production and distribution. Two delivery scenarios are compared: The first examines Blu‐ray discs (BDs) delivered by retail stores, and the second, games files downloaded over broadband Internet. Contrary to findings in previous research on music distribution, distribution of games by physical BDs results in lower greenhouse gas emissions than by Internet download. The estimated carbon emissions from downloading only fall definitively below that of BDs for games smaller than 1.3 GB. Sensitivity analysis indicates that as average game file sizes increase, and the energy intensity of the Internet falls, the file size at which BDs would result in lower emissions than downloads could shift either up‐ or downward over the next few years. Overall, the results appear to be broadly applicable to title games within the European Union (EU), and for larger‐than‐average sized games in the United States. Further research would be needed to confirm whether similar findings would apply in future years with changes in game size and Internet efficiency. The study findings serve to illustrate why it is not always true that digital distribution of media will have lower carbon emissions than distribution by physical means when file sizes are large.

Understanding the Impact of Lifestyle on Individual Carbon-footprint

According to the International Energy Agency, India is the fourth largest emitter of global greenhouse gas (GHG) emissions contributing about 5% of total emissions [1]. But it is also the home to a third of the world's poor. There also exists a large disparity in the living conditions and lifestyles of people living in the rural and urban India. Based on geographical location and lifestyle, an individual's contribution to the global carbon footprint has been estimated in this study. Data on consumption of goods and services resulting in GHG emissions was gathered at the household level through a door to door survey from few localities in Mumbai and rural areas within 100km of boundary. Equivalent carbon emission factors were used to estimate the carbon footprint from major sources like electricity, transport, cooking fuel and food for these areas. The average annual per capita carbon footprint was estimated to be 2.5 tons CO2e in the urban area and 0.85 tons CO2e in the rural area. For each of the areas (rural and urban), substantial variation in carbon footprint has also been observed across different socio-economic classes. Limitations: Indirect emissions, emissions related to work and public place were excluded. This study looked at the sectoral contribution (activity-wise, e.g. cooking, transportation etc.) as well as the rural-urban disparity in the individual carbon footprint; which was done for the first time in India.

Indirect Carbon Emission Measurement of Electric Vehicle in China

The issue of carbon emissions by electric vehicle(EV) was studied using life cycle theory, and the work provided decision basis for creating China’s CO2 emission standards for auto. The results show that the carbon equivalent emission of coal-fired generation side per unit electricity consumed by EV is lower than the level of normal passenger car in China, but still higher than the forced limit on auto emission within the EU.

Environmental, economic and social costs and benefits of a packaging waste management system: A Portuguese case study

The impact of the management of packaging waste on the environment, economic growth and job creation is analyzed in this paper. This integrated assessment intends to cover a gap in the literature for this type of studies, using the specific case study of the Portuguese packaging waste management system (SIGRE).The net environmental benefits associated with the management of packaging waste, are calculated using the Life Cycle Assessment methodology. The results show that, for the categories studied, the impacts associated to SIGRE's various activities are surpassed by the benefits associated to material and energy recovery, with special focus on recycling. For example, in 2011 SIGRE avoided the emission of 116kt CO2 equiv. – the equivalent carbon emission of the electricity consumption of 124.000 households in Portugal.The economic impact of SIGRE is evaluated through Input–Output Analysis. It was found that SIGRE's activities also have a significant economic impact. For example, their added value are ranked amongst the upper third of the economic activities with highest multiplier effect at national level: this means that for each Euro of value added generated within SIGRE, 1.25 additional € are added to the rest of the economy (multiplier effect of 2.25).Regarding the social impacts of SIGRE, the number of direct jobs associated with the system is estimated to be more than two thousand and three hundred workers. Out of these, 83% are connected to the management of municipal waste packaging (selective collection and sorting), 15% are connected to the management of non-municipal packaging waste and only 2% are connected to the Sociedade Ponto Verde (SPV, green dot society in English) – the management entity responsible for SIGRE.In general terms, the results obtained provide quantitative support to the EEA (2011) suggestion that moving up the waste hierarchy – from landfilling to recycling – creates jobs and boosts the economy.

Research of Carbon Emissions of Highway Operation Period Based on Grey Relational Analysis

The CO2 emissions of highway transportation industry are huge. In order to study factors affecting carbon emissions of highway operation period, selected five primary route design indicators to analyze. The five indicators were Speed, Gradient, Radius of Curvature, IRI, Traffic Volume and Green Belt. Combined the existing Carbon Accounting Model and the Carbon Accounting Software of Highway Operation Period[4], which could calculate the equivalent carbon emissions. By using Gray relational analysis method, calculated the relational degrees between route design indicators and carbon emissions of highway operation period. At last, found that the most important factor affecting carbon emissions of highway operation period was average daily traffic volume. The research will be helpful to discuss the carbon emissions of highway operation period in a targeted manner.

Impacts of an extreme cyclone event on landscape-scale savanna fire, productivity and greenhouse gas emissions

North Australian tropical savanna accounts for 12% of the world’s total savanna land cover. Accordingly, understanding processes that govern carbon, water and energy exchange within this biome is critical to global carbon and water budgeting. Climate and disturbances drive ecosystem carbon dynamics. Savanna ecosystems of the coastal and sub-coastal of north Australia experience a unique combination of climatic extremes and are in a state of near constant disturbance from fire events (1 in 3 years), storms resulting in windthrow (1 in 5–10 years) and mega-cyclones (1 in 500–1000 years). Critically, these disturbances occur over large areas creating a spatial and temporal mosaic of carbon sources and sinks. We quantify the impact on gross primary productivity (GPP) and fire occurrence from a tropical mega-cyclone, tropical Cyclone Monica (TC Monica), which affected 10 400 km2 of savanna across north Australia, resulting in the mortality and severe structural damage to ∼140 million trees. We estimate a net carbon equivalent emission of 43 Tg of CO2-e using the moderate resolution imaging spectroradiometer (MODIS) GPP (MOD17A2) to quantify spatial and temporal patterns pre- and post-TC Monica. GPP was suppressed for four years after the event, equivalent to a loss of GPP of 0.5 Tg C over this period. On-ground fuel loads were estimated to potentially release 51.2 Mt CO2-e, equivalent to ∼10% of Australia’s accountable greenhouse gas emissions. We present a simple carbon balance to examine the relative importance of frequency versus impact for a number of key disturbance processes such as fire, termite consumption and intense but infrequent mega-cyclones. Our estimates suggested that fire and termite consumption had a larger impact on Net Biome Productivity than infrequent mega-cyclones. We demonstrate the importance of understanding how climate variability and disturbance impacts savanna dynamics in the context of the increasing interest in using savanna landscapes for enhanced carbon sinks in emission offset schemes.

Influence of farmyard manure application and mineral fertilization on yield sustainability, carbon sequestration potential and soil property of gardenpea–french bean cropping system in the Indian Himalayas

Sustainability of agricultural systems has become an important issue all over the world. Hence, sustainability and climate resilience of gardenpea–french bean cropping system was evaluated by yield trends, C sequestration and emission reduction and soil properties as affected by four application rates of farmyard manure (FYM) (5–20tha−1) vis-à-vis mineral fertilization, integrated nutrient management (INM) practices as 50% recommended NPK+FYM at 5tha−1 and un-amended control after six years of cropping in the Indian Himalayas. The highest sustainable yield index of 0.606 was achieved with the application of 20tFYMha−1 (FYM20). The carbon sequestration potential of FYM20 plots was about 459 and 193% more than NPK and INM plots, respectively. The same plots reduced 53 and 24% carbon equivalent emission with comparison to NPK and INM application, respectively. The soil cation exchange capacity (CEC) under FYM20 plots was 22 and 11% higher than NPK and INM plots. The soil cracking volume under FYM20 plots (57cm3m−2 area) was very less compared to NPK (324cm3m−2 area) and INM (154cm3m−2 area) plots. The morning soil temperature (0–15cm depth) in coldest week of last year experimentation under FYM20 plots was moderated by 0.60 and 0.47°C than NPK and INM plots, respectively. Successive increase of FYM level improved soil organic C, microbial colony formation unit, dehydrogenase activity, bulk density and soil cracking surface area and the best values for all soil properties were recorded under FYM20 plots. Application of 20tFYMha−1 produced 54 and 29% higher gardenpea equivalent pod yield of the system than mineral fertilization and INM, respectively. The principal component analysis revealed that soil CEC was the most important property (among the selected soil parameters) contributing to the pod yield. Soil organic carbon markedly improved other soil properties as evident from correlations. Organic production system with FYM 20tha−1 could be recommended for climate resilient sustainable yield and better soil property of gardenpea–french bean cropping system than mineral fertilization and INM in the Indian Himalayan regions.

Carbon footprint of patient journeys through primary care: a mixed methods approach

The NHS has a target of cutting its carbon dioxide (CO2) emissions by 80% below 1990 levels by 2050. Travel comprises 17% of the NHS carbon footprint. This carbon footprint represents the total CO2 emissions caused directly or indirectly by the NHS. Patient journeys have previously been planned largely without regard to the environmental impact. The potential contribution of 'avoidable' journeys in primary care is significant. To investigate the carbon footprint of patients travelling to and from a general practice surgery, the issues involved, and potential solutions for reducing patient travel. A mixed methods study in a medium-sized practice in Yorkshire. During March 2012, 306 patients completed a travel survey. GIS maps of patients' travel (modes and distances) were produced. Two focus groups (12 clinical and 13 non-clinical staff) were recorded, transcribed, and analysed using a thematic framework approach. The majority (61%) of patient journeys to and from the surgery were made by car or taxi; main reasons cited were 'convenience', 'time saving', and 'no alternative' for accessing the surgery. Using distances calculated via ArcGIS, the annual estimated CO2 equivalent carbon emissions for the practice totalled approximately 63 tonnes. Predominant themes from interviews related to issues with systems for booking appointments and repeat prescriptions; alternative travel modes; delivering health care; and solutions to reducing travel. The modes and distances of patient travel can be accurately determined and allow appropriate carbon emission calculations for GP practices. Although challenging, there is scope for identifying potential solutions (for example, modifying administration systems and promoting walking) to reduce 'avoidable' journeys and cut carbon emissions while maintaining access to health care.

Prévalence de l’hypertension artérielle pulmonaire au cours du lupus érythémateux systémique

Sustainability of agricultural systems has become an important issue all over the world. Hence, sustainability and climate resilience of gardenpea–french bean cropping system was evaluated by yield trends, C sequestration and emission reduction and soil properties as affected by four application rates of farmyard manure (FYM) (5–20 t ha−1) vis-à-vis mineral fertilization, integrated nutrient management (INM) practices as 50% recommended NPK + FYM at 5 t ha−1 and un-amended control after six years of cropping in the Indian Himalayas. The highest sustainable yield index of 0.606 was achieved with the application of 20 t FYM ha−1 (FYM20). The carbon sequestration potential of FYM20 plots was about 459 and 193% more than NPK and INM plots, respectively. The same plots reduced 53 and 24% carbon equivalent emission with comparison to NPK and INM application, respectively. The soil cation exchange capacity (CEC) under FYM20 plots was 22 and 11% higher than NPK and INM plots. The soil cracking volume under FYM20 plots (57 cm3 m−2 area) was very less compared to NPK (324 cm3 m−2 area) and INM (154 cm3 m−2 area) plots. The morning soil temperature (0–15 cm depth) in coldest week of last year experimentation under FYM20 plots was moderated by 0.60 and 0.47 °C than NPK and INM plots, respectively. Successive increase of FYM level improved soil organic C, microbial colony formation unit, dehydrogenase activity, bulk density and soil cracking surface area and the best values for all soil properties were recorded under FYM20 plots. Application of 20 t FYM ha−1 produced 54 and 29% higher gardenpea equivalent pod yield of the system than mineral fertilization and INM, respectively. The principal component analysis revealed that soil CEC was the most important property (among the selected soil parameters) contributing to the pod yield. Soil organic carbon markedly improved other soil properties as evident from correlations. Organic production system with FYM 20 t ha−1 could be recommended for climate resilient sustainable yield and better soil property of gardenpea–french bean cropping system than mineral fertilization and INM in the Indian Himalayan regions.

A Systems Approach to Sustainable Technical Product Design

SummaryMany existing methods for sustainable technical product design focus on environmental efficiency while lacking a framework for a holistic, sustainable design approach that includes combined social, technical, economic, and environmental aspects in the whole product life cycle, and that provides guidance on a technical product development level. This research proposes a framework for sustainable technical product design in the case of skis. We developed a ski under the Grown brand, benchmarked according to social, environmental, economic, and technical targets, following an initial sustainability assessment, and delivered the first environmental life cycle assessment (ELCA) and the first social life cycle assessment (SLCA) of skis. The framework applies a virtual development process as a combination of ELCA to calculate the environmental footprint as carbon equivalents of all materials and processes and a technical computer‐aided design (CAD) and computer‐aided engineering (CAE) simulation and virtual optimization using parameter studies for the nearly prototype‐free development of the benchmarked skis. The feedback loops between life cycle assessment (LCA) and virtual simulation led to the elimination of highly energy intensive materials, to the pioneering use of basalt fibers in skis, to the optimization of the use of natural materials using protective coatings from natural resins, and to the optimization of the production process. From an environmental perspective, a minimum 32% reduction in carbon equivalent emissions of materials in relation to other comparably performing skis has been achieved, as well as a pioneering step forward toward transparent communication of the environmental performance by the individual, comparable, and first published ski carbon footprint per volume unit.

Greenhouse gas emission in relation to labile soil C, N pools and functional microbial diversity as influenced by 39 years long-term fertilizer management in tropical rice

Impacts of 39-years of fertilizer and manure application on greenhouse gas (GHG) emissions viz. methane, carbon dioxide and nitrous oxide, soil labile carbon (C) and nitrogen (N) pools, functional microbial diversity were investigated in a tropical flooded rice (Oryza sativa L.). The treatments included non-fertilized control, N, farmyard manure (FYM), FYM+N, NPK and FYM+NPK. Annual cumulative GHGs emissions after 39 years of intensive rice–rice cultivation were significantly higher in FYM+NPK treatments than other treatments. The global warming potential (GWP) in 100 years time scale and carbon equivalent emission (CEE) were increased significantly under the combined application of FYM+NPK by 88.4% over control. The carbon efficiency ratio (CER) was significantly higher (p≤0.05) in NPK as compared to others. The annual emissions of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2-C) in FYM+NPK were 177.6, 1.28, 1407kgha−1, respectively, in tropical rice–rice system (wet season rice-fallow–dry season rice-fallow) which were significantly higher (p≤0.05) than other treatments. Although the GHGs emissions were more under FYM+NPK treatment, it helps to maintain soil fertility and supported sustainable rice yield. The soil labile C, N pools, soil enzymatic activities and microbial populations were significantly higher under this treatment which is the indicators of improved soil fertility. Stepwise regression analysis of GHGs emission with related soil parameters was performed to predict seasonal fluxes from tropical rice.

A Case Study of Carbon Footprint on Liquor Packaging

The increasing concern on low carbon and environment protection has aroused a broader awareness of the sustainable development issues to be given to the environmental impacts of packaging products through the whole life cycle. The research of carbon footprint takes the high lights among these studies. The calculation of carbon emissions on commodities has shown many advantages on estimation of global greenhouse gas emissions. In this work, glass bottle liquor packaging was selected as the researching object, its equivalent carbon emissions were investigated by hybrid life cycle method. Through the carbon emissions research of the processes during the whole life cycle including raw materials’ production, packaging process, transportation, consumption and recycling, the carbon footprint on liquor packaging was calculated. The results indicated that the transportation and production of glass bottle contribute the most parts of total carbon emissions, which provides a case support for energy conservation and the development of green packaging.

Potential of the daycent model to predict change in greenhouse gas emissions with cessation of tillage for cultivation of perennial energy crops

Bioenergy may make up a signifi cant proportion of future renewable energy supplies, and for perennial feedstocks, this will require conversion of land to a no till (NT) system. Previous studies suggest that NT leads to increased soil organic matter (SOM) storage, which breaks down over time resulting in increased N2O emissions. This may not indicate net total increase, since indirect emissions from eroded SOM with tillage should be considered. Given the high global warming potential of N2O, it is crucial to predict net change in emissions rather than focusing only on potential for C storage. The DayCent model has been used to represent both tilled [1, 2], and untilled [3, 4] agroecosystems. This study assesses its suitability to represent land conversion to NT; fi rst by exploring model structure and process representation, and secondly by using sensitivity analysis to identify whether DayCent matches published variation between tillage regimes. DayCent predicts increasing surface and slow-decomposing soil carbon for no till, but not the expected increase in N2O emissions. It has been suggested that changes in soil structure with tillage affect infi ltration, and therefore nitrifi cation and denitrifi cation processes leading to N2O emissions [5, 6]. For accurate simulation of the relationship to precipitation, DayCent should ideally represent differing soil water capacity (SWC) and porosity between tillage regimes, and the impacts on water filled pore space (WFPS). DayCent also fails to appropriately respond to low C:N ratio residue applications, or to simulate interaction between tillage and nutrient applications. Recommendations are provided for improvements to DayCent to resolve these issues and enable more robust scenario analysis. Assuming improved performance at validation, this should facilitate more accurate carbon equivalent emissions for land use change, incorporating N2O.

Evaluation of the potential emissions reductions from the use of CHP systems in different commercial buildings

Combined heating and power (CHP) systems generate electricity near the site of use and capture the waste heat for space heating or hot water. Under the right conditions, a CHP system can reduce the harmful emissions resulting from power production, causing less greenhouse gases to be released than a reference system where power is purchased from the electricity grid. Different building types may be more or less likely to save emissions with CHP systems based on the electrical and thermal needs of the building. This investigation evaluates seven different types of buildings located in Chicago, Illinois for their potential to reduce CO2, NOx, and CH4 emissions using a CHP system. The CHP system modeled is sized to provide 30% of the average hourly electricity needs of each building. The total carbon equivalent emissions, primary energy consumption (PEC), and operational cost of a CHP system are presented along with those of a reference system. In addition, the CHP system efficiency is analyzed with respect to the fraction of the thermal load that is satisfied by the CHP system (Rh). Results show that a CHP system would reduce emissions for all buildings studied, with more than 21% of carbon equivalent emissions reduced for an outpatient health care building. PEC and operational cost would be reduced with the use of a CHP system for some of the buildings. In general it is beneficial to have high Rh values to provide better emissions, cost and PEC reduction from the CHP system operation.

Potential of the daycent model to predict change in greenhouse gas emissions with cessation of tillage for cultivation of perennial energy crops

Bioenergy may make up a signifi cant proportion of future renewable energy supplies, and for perennial feedstocks, this will require conversion of land to a no till (NT) system. Previous studies suggest that NT leads to increased soil organic matter (SOM) storage, which breaks down over time resulting in increased N2O emissions. This may not indicate net total increase, since indirect emissions from eroded SOM with tillage should be considered. Given the high global warming potential of N2O, it is crucial to predict net change in emissions rather than focusing only on potential for C storage. The DayCent model has been used to represent both tilled [1, 2], and untilled [3, 4] agroecosystems. This study assesses its suitability to represent land conversion to NT; fi rst by exploring model structure and process representation, and secondly by using sensitivity analysis to identify whether DayCent matches published variation between tillage regimes. DayCent predicts increasing surface and slow-decomposing soil carbon for no till, but not the expected increase in N2O emissions. It has been suggested that changes in soil structure with tillage affect infi ltration, and therefore nitrifi cation and denitrifi cation processes leading to N2O emissions [5, 6]. For accurate simulation of the relationship to precipitation, DayCent should ideally represent differing soil water capacity (SWC) and porosity between tillage regimes, and the impacts on water fi lled pore space (WFPS). DayCent also fails to appropriately respond to low C:N ratio residue applications, or to simulate interaction between tillage and nutrient applications. Recommendations are provided for improvements to DayCent to resolve these issues and enable more robust scenario analysis. Assuming improved performance at validation, this should facilitate more accurate carbon equivalent emissions for land use change, incorporating N2O.