Additional Greenhouse Gas Research Articles

Estimating the Additional Greenhouse Gas Emissions in Korea: Focused on Demolition of Asbestos Containing Materials in Building.

When asbestos containing materials (ACM) must be removed from the building before demolition, additional greenhouse gas (GHG) emissions are generated. However, precedent studies have not considered the removal of ACM from the building. The present study aimed to develop a model for estimating GHG emissions created by the ACM removal processes, specifically the removal of asbestos cement slates (ACS). The second objective was to use the new model to predict the total GHG emission produced by ACM removal in the entire country of Korea. First, an input-equipment inventory was established for each step of the ACS removal process. Second, an energy consumption database for each equipment type was established. Third, the total GHG emission contributed by each step of the process was calculated. The GHG emissions generated from the 1,142,688 ACS-containing buildings in Korea was estimated to total 23,778 tonCO2eq to 132,141 tonCO2eq. This study was meaningful in that the emissions generated by ACS removal have not been studied before. Furthermore, the study deals with additional problems that can be triggered by the presence of asbestos in building materials. The method provided in this study is expected to contribute greatly to the calculation of GHG emissions caused by ACM worldwide.

Greenhouse gas emissions from natural ecosystems and agricultural lands in sub-Saharan Africa: synthesis of available data and suggestions for further research

Abstract. This paper summarizes currently available data on greenhouse gas (GHG) emissions from African natural ecosystems and agricultural lands. The available data are used to synthesize current understanding of the drivers of change in GHG emissions, outline the knowledge gaps, and suggest future directions and strategies for GHG emission research. GHG emission data were collected from 75 studies conducted in 22 countries (n = 244) in sub-Saharan Africa (SSA). Carbon dioxide (CO2) emissions were by far the largest contributor to GHG emissions and global warming potential (GWP) in SSA natural terrestrial systems. CO2 emissions ranged from 3.3 to 57.0 Mg CO2 ha−1 yr−1, methane (CH4) emissions ranged from −4.8 to 3.5 kg ha−1 yr−1 (−0.16 to 0.12 Mg CO2 equivalent (eq.) ha−1 yr−1), and nitrous oxide (N2O) emissions ranged from −0.1 to 13.7 kg ha−1 yr−1 (−0.03 to 4.1 Mg CO2 eq. ha−1 yr−1). Soil physical and chemical properties, rewetting, vegetation type, forest management, and land-use changes were all found to be important factors affecting soil GHG emissions from natural terrestrial systems. In aquatic systems, CO2 was the largest contributor to total GHG emissions, ranging from 5.7 to 232.0 Mg CO2 ha−1 yr−1, followed by −26.3 to 2741.9 kg CH4 ha−1 yr−1 (−0.89 to 93.2 Mg CO2 eq. ha−1 yr−1) and 0.2 to 3.5 kg N2O ha−1 yr−1 (0.06 to 1.0 Mg CO2 eq. ha−1 yr−1). Rates of all GHG emissions from aquatic systems were affected by type, location, hydrological characteristics, and water quality. In croplands, soil GHG emissions were also dominated by CO2, ranging from 1.7 to 141.2 Mg CO2 ha−1 yr−1, with −1.3 to 66.7 kg CH4 ha−1 yr−1 (−0.04 to 2.3 Mg CO2 eq. ha−1 yr−1) and 0.05 to 112.0 kg N2O ha−1 yr−1 (0.015 to 33.4 Mg CO2 eq. ha−1 yr−1). N2O emission factors (EFs) ranged from 0.01 to 4.1 %. Incorporation of crop residues or manure with inorganic fertilizers invariably resulted in significant changes in GHG emissions, but results were inconsistent as the magnitude and direction of changes were differed by gas. Soil GHG emissions from vegetable gardens ranged from 73.3 to 132.0 Mg CO2 ha−1 yr−1 and 53.4 to 177.6 kg N2O ha−1 yr−1 (15.9 to 52.9 Mg CO2 eq. ha−1 yr−1) and N2O EFs ranged from 3 to 4 %. Soil CO2 and N2O emissions from agroforestry were 38.6 Mg CO2 ha−1 yr−1 and 0.2 to 26.7 kg N2O ha−1 yr−1 (0.06 to 8.0 Mg CO2 eq. ha−1 yr−1), respectively. Improving fallow with nitrogen (N)-fixing trees led to increased CO2 and N2O emissions compared to conventional croplands. The type and quality of plant residue in the fallow is an important control on how CO2 and N2O emissions are affected. Throughout agricultural lands, N2O emissions slowly increased with N inputs below 150 kg N ha−1 yr−1 and increased exponentially with N application rates up to 300 kg N ha−1 yr−1. The lowest yield-scaled N2O emissions were reported with N application rates ranging between 100 and 150 kg N ha−1. Overall, total CO2 eq. emissions from SSA natural ecosystems and agricultural lands were 56.9 ± 12.7 × 109 Mg CO2 eq. yr−1 with natural ecosystems and agricultural lands contributing 76.3 and 23.7 %, respectively. Additional GHG emission measurements are urgently required to reduce uncertainty on annual GHG emissions from the different land uses and identify major control factors and mitigation options for low-emission development. A common strategy for addressing this data gap may include identifying priorities for data acquisition, utilizing appropriate technologies, and involving international networks and collaboration.

Long-term annual burning of grassland increases CO2 emissions from soils

Grasslands have potential to mitigate against climate change because of their large capacity to store soil organic carbon (SOC). However, the long-term impact of grassland management such as burning, which is still common in many areas of the world, on SOC is still a matter of debate. The objective of this study was to quantify the long-term effects of annual burning on CO2 output from soils and SOC stocks. The study was performed on a 62years old field trial comparing annual burning (AB) to no burning associated with tree encroachment (NB), and to annual mowing (AM) with all treatments laid out in randomized block design with three replicates per treatment. CO2 emissions from soil were continuously measured over two years and were correlated to soil chemical and physical properties. AB and AM produced 30 and 34% greater CO2 emissions from soil than NB (1.80±0.13 vs. 2.34±0.18 and 2.41±0.17gC-CO2m−2d−1 for NB, AB and AM respectively). AB and AM also produced greater CO2 emissions from soil and per gram of soil carbon (1.32±0.1 and 1.35±0.1mgC-CO2gC−1d−1, respectively) than NB (1.05±0.07mgC-CO2gC−1d−1), which corresponded to significant differences of respectively 26% and 29%. Overall, CO2 emissions from soil (per m2) significantly increased with soil water content (r=0.72) followed by SOC stocks (r=0.59), SOC content (r=0.50), soil bulk density (r=0.49), soil temperature (r=0.47), C:N ratio (r=0.46) and mean weight diameter (r=0.38). These findings suggest that long-term annual burning increases CO2 output from soils. Additional greenhouse gases emissions from burning itself and alternative grassland management techniques were finally discussed.

Vehicle to Grid regulation services of electric delivery trucks: Economic and environmental benefit analysis

Concerns regarding the fuel costs and climate change impacts associated with petroleum combustion are among the main driving factors for the adoption of electric vehicles. Future commercial delivery truck fleets may include Battery Electric Vehicles (BEVs) and Extended Range Electric Vehicles (EREVs); in addition to savings on fuel and maintenance costs, the introduction of these grid accessible electric vehicles will also provide fleet owners with possible Vehicle to Grid (V2G) opportunities. This study investigates the potential net present revenues and greenhouse gas (GHG) emission mitigation of V2G regulation services provided by electric trucks in a typical fleet. The total cost of ownership and the life-cycle GHG emissions of electric trucks are also analyzed and compared to those of traditional diesel trucks. To account for uncertainties, possible ranges for key parameters are considered instead of only considering fixed single data values for each parameter. The results of this research indicate that providing V2G regulation services for electric trucks could yield considerable additional revenues ($20,000–50,000) and significant GHG emission savings (approximately 300 ton CO2) compared to conventional diesel trucks.

Estimating Carbon Emissions due to Freeway Incidents by Using Macroscopic Traffic Flow Models

PURPOSES : The purpose of this study is to develop a methodology for estimating additional carbon emissions due to freeway incidents. METHODS : As our country grows, our highway policy has mainly neglected the environmental and social sectors. However, with the formation of a national green growth keynote and an increase in the number of people interested in environmental and social issues, problems related to social issues, such as traffic accidents and congestion, and environmental issues, such as the impact of air pollution caused by exhaust gases that are emitted from highway vehicles, are beginning to be discussed. Accordingly, studies have been conducted on a variety of environmental aspects in the field of road transport, and for the quantitative calculation of greenhouse gas emissions, using various methods. However, in order to observe the effects of carbon emissions, microscopic simulations must use many difficult variables such as cost, analysis time, and ease of analysis process. In this study, additional greenhouse gas emissions that occur because of highway traffic accidents were classified by type (incident handling time, number of lanes blocked, freeway level of service), and the annual additional emissions based on incidents were calculated. According to the results, congestion length and emissions tend to increase with an increase in incident clearance time, number of occupied lanes, and worsening level of service. Using this data, we analyzed accident data on the Gyeong-bu Expressway (Yang-Jae IC - Osan IC) for a year. RESULTS : Additional greenhouse gas emissions that occur because of highway traffic accidents were classified by type (incident handling time, number of lanes blocked, freeway level of service) and annual additional emissions caused by accidents were calculated. CONCLUSIONS : In this study, a methodology for estimating carbon emissions due to freeway incidents was developed that incorporates macroscopic flow models. The results of the study are organized in the form of a look-Up table that calculates carbon emissions rather easily.

The role of waterborne carbon in the greenhouse gas balance of drained and re-wetted peatlands

Accounting for greenhouse gas (GHG) emissions and removals in managed ecosystems has generally focused on direct land–atmosphere fluxes, but in peatlands a significant proportion of total carbon loss occurs via fluvial transport. This study considers the composition of this ‘waterborne carbon’ flux, its potential contribution to GHG emissions, and the extent to which it may change in response to land-management. The work describes, and builds on, a methodology to account for major components of these emissions developed for the 2013 Wetland Supplement of the Intergovernmental Panel on Climate Change. We identify two major components of GHG emissions from waterbodies draining organic soil: i) ‘on site’ emissions of methane (and to a lesser extent CO2) from drainage ditches located within the peatland; and ii) ‘off site’ emissions of CO2 resulting from downstream oxidation of dissolved and particulate organic carbon (DOC and POC) within the aquatic system. Methane emissions from ditches were found to be large in many cases (mean 60 g CH4 m−2 year−1 based on all reported values), countering the view that methane emissions cease following wetland drainage. Emissions were greatest from ditches in intensive agricultural peatlands, but data were sparse and showed high variability. For DOC, the magnitude of the natural flux varied strongly with latitude, from 5 g C m−2 year−1 in northern boreal peatlands to 60 g C m−2 year−1 in tropical peatlands. Available data suggest that DOC fluxes increase by around 60 % following drainage, and that this increase may be reversed in the longer-term through re-wetting, although variability between studies was high, especially in relation to re-wetting response. Evidence regarding the fate of DOC is complex and inconclusive, but overall suggests that the majority of DOC exported from peatlands is converted to CO2 through photo- and/or bio-degradation in rivers, standing waters and oceans. The contribution of POC export to GHG emissions is even more uncertain, but we estimate that over half of exported POC may eventually be converted to CO2. Although POC fluxes are normally small, they can become very large when bare peat surfaces are exposed to fluvial erosion. Overall, we estimate that waterborne carbon emissions may contribute about 1–4 t CO2-eq ha−1 year−1 of additional GHG emissions from drained peatlands. For a number of worked examples this represented around 15–50 % of total GHG emissions.

A simplified, data-constrained approach to estimate the permafrost carbon-climate feedback.

We present an approach to estimate the feedback from large-scale thawing of permafrost soils using a simplified, data-constrained model that combines three elements: soil carbon (C) maps and profiles to identify the distribution and type of C in permafrost soils; incubation experiments to quantify the rates of C lost after thaw; and models of soil thermal dynamics in response to climate warming. We call the approach the Permafrost Carbon Network Incubation–Panarctic Thermal scaling approach (PInc-PanTher). The approach assumes that C stocks do not decompose at all when frozen, but once thawed follow set decomposition trajectories as a function of soil temperature. The trajectories are determined according to a three-pool decomposition model fitted to incubation data using parameters specific to soil horizon types. We calculate litterfall C inputs required to maintain steady-state C balance for the current climate, and hold those inputs constant. Soil temperatures are taken from the soil thermal modules of ecosystem model simulations forced by a common set of future climate change anomalies under two warming scenarios over the period 2010 to 2100. Under a medium warming scenario (RCP4.5), the approach projects permafrost soil C losses of 12.2–33.4 Pg C; under a high warming scenario (RCP8.5), the approach projects C losses of 27.9–112.6 Pg C. Projected C losses are roughly linearly proportional to global temperature changes across the two scenarios. These results indicate a global sensitivity of frozen soil C to climate change (γ sensitivity) of −14 to −19 Pg C °C−1 on a 100 year time scale. For CH4 emissions, our approach assumes a fixed saturated area and that increases in CH4 emissions are related to increased heterotrophic respiration in anoxic soil, yielding CH4 emission increases of 7% and 35% for the RCP4.5 and RCP8.5 scenarios, respectively, which add an additional greenhouse gas forcing of approximately 10–18%. The simplified approach presented here neglects many important processes that may amplify or mitigate C release from permafrost soils, but serves as a data-constrained estimate on the forced, large-scale permafrost C response to warming.

Identifying/Quantifying Environmental Trade-offs Inherent in GHG Reduction Strategies for Coal-Fired Power.

Improvements to coal power plant technology and the cofired combustion of biomass promise direct greenhouse gas (GHG) reductions for existing coal-fired power plants. Questions remain as to what the reduction potentials are from a life cycle perspective and if it will result in unintended increases in impacts to air and water quality and human health. This study provides a unique analysis of the potential environmental impact reductions from upgrading existing subcritical pulverized coal power plants to increase their efficiency, improving environmental controls, cofiring biomass, and exporting steam for industrial use. The climate impacts are examined in both a traditional-100 year GWP-method and a time series analysis that accounts for emission and uptake timing over the life of the power plant. Compared to fleet average pulverized bed boilers (33% efficiency), we find that circulating fluidized bed boilers (39% efficiency) may provide GHG reductions of about 13% when using 100% coal and reductions of about 20-37% when cofiring with 30% biomass. Additional greenhouse gas reductions from combined heat and power are minimal if the steam coproduct displaces steam from an efficient natural gas boiler. These upgrades and cofiring biomass can also reduce other life cycle impacts, although there may be increased impacts to water quality (eutrophication) when using biomass from an intensely cultivated source. Climate change impacts are sensitive to the timing of emissions and carbon sequestration as well as the time horizon over which impacts are considered, particularly for long growth woody biomass.

Health effects of adopting low greenhouse gas emission diets in the UK

ObjectiveDietary changes which improve health are also likely to be beneficial for the environment by reducing emissions of greenhouse gases (GHG). However, previous analyses have not accounted for the potential...

Enhancement of farmland greenhouse gas emissions from leakage of stored CO2: Simulation of leaked CO2 from CCS

The effects of leaked CO2 on plant and soil constitute a key objective of carbon capture and storage (CCS) safety. The effects of leaked CO2 on trace soil gas (e.g., methane (CH4) and nitrous oxide (N2O) emissions in farmlands are not well-understood. This study simulated the effects of elevated soil CO2 on CH4 and N2O through pot experiments. The results revealed that significant increases of CH4 and N2O emissions were induced by the simulated CO2 leakages; the emission rates of CH4 and N2O were substantial, reaching about 222 and 48 times than that of the control, respectively. The absolute global warming potentials (GWPs) of the additional CH4 and N2O are considerable, but the cumulative GWPs of the additional CH4 and N2O only accounted for 0.03% and 0.06%, respectively, of the cumulative amount of leaked CO2 under high leakage conditions. The results demonstrate that leakage from CCS projects may lead to additional greenhouse gas emissions from soil; however, in general, the amount of additional CH4 and N2O emissions is negligible when compared with the amount of leaked CO2.

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.

Market-driven emissions from recovery of carbon dioxide gas.

This article uses a market-based allocation method in a consequential life cycle assessment (LCA) framework to estimate the environmental emissions created by recovering carbon dioxide (CO2). We find that 1 ton of CO2 recovered as a coproduct of chemicals manufacturing leads to additional greenhouse gas emissions of 147-210 kg CO2 eq , while consuming 160-248 kWh of electricity, 254-480 MJ of heat, and 1836-4027 kg of water. The ranges depend on the initial and final purity of the CO2, particularly because higher purity grades require additional processing steps such as distillation, as well as higher temperature and flow rate of regeneration as needed for activated carbon treatment and desiccant beds. Higher purity also reduces process efficiency due to increased yield losses from regeneration gas and distillation reflux. Mass- and revenue-based allocation methods used in attributional LCA estimate that recovering CO2 leads to 19 and 11 times the global warming impact estimated from a market-based allocation used in consequential LCA.

Greenhouse gas emissions from enteric fermentation and manure on organic and conventional dairy farms—an analysis based on farm network data

Feed and manure composition and qualities in an organic and conventional dairy farm network in Germany (22 farm pairs) were analysed. Related greenhouse gas (GHG) emissions from enteric fermentation and from animal excretions were calculated by using two methods each. Feeding and feedstuff quality were farm specific. On average, organic dairy cows received significantly less concentrates, maize silage and straw and significantly more pasture and hay than conventional dairy cows. No differences were found for feeding grass silage. Results for methane (CH4) emissions from enteric fermentation depended strongly on the calculation methodology. They were higher when feed quality was considered as an input parameter (average GHG emissions 3822 and 3759 kg CO2-eq. cow−1 a−1 on organic and conventional farms) as opposed to when only feed intake was considered (2852 and 3112 kg CO2-eq. cow−1 a−1). Differences between the methods were particularly prominent when high amounts of fibre-rich feedstuff were used and, with regard to product-related emissions, at lower milk yields. GHG emissions from manure are also directly connected with feed intake and quality. Manure qualities and storage conditions on the farms were highly variable. On average, the related GHG emission potential was similar in liquid and solid manures (32 kg CO2-eq. t−1 fresh matter). Since feed quality management on farms influences milk yield, enteric CH4 emissions and manure composition, it should be part of advisory concepts that aim at reducing GHG emissions in milk production. Technical changes in manure storage and handling offer an additional GHG reduction potential.

Importance of Male Fertility Control in Family Planning

The world population, currently estimated to be almost seven billion, is expected to double in less than four decades. The projected population growth will cause severe competition for existing resources, not to mention the issue of overcrowding of the planet and additional greenhouse gases that will have an adverse effect on the ecological health of the planet. A recent survey conducted by the United Nations Population Control Division shows that the majority of today's young men in many countries are willing to participate in family planning by taking full control of their fertility, an important global health issue. However, the contraceptive needs of tens of millions of men/couples go unmet every single day and results in millions of unwanted pregnancies. Ever since the approval of the birth control pill by the Food and Drug Administration (FDA) in 1960, scientists have been hoping for a male equivalent. It has, however, been a difficult road, in part because of the complicated science of the male reproductive system. It is easier to control a monthly event of ovulation in women than to regulate the production of millions of fertile spermatozoa every day in men. Thus, the contraceptive options for men have not changed in decades and are still limited to the use of condoms, a timely withdrawal/pulling out (coitus interruptus) or vasectomy, a minor surgical procedure in which the vas deferens is occluded to prevent the release of spermatozoa during ejaculation. The first two approaches have a relatively higher failure rate, whereas the last approach is largely irreversible and not suitable for younger men. In this article, we will discuss various approaches currently available for men to take control of their fertility. Our intention is to discuss the details of three similar approaches that will provide safe, affordable and reversible contraception for men and are close to being approved for use by millions of men around the globe. The availability of safe, reversible and reliable male contraceptives will allow men and women to take full control of their fertility in family planning.

Climate friendliness of cocoa agroforests is compatible with productivity increase

There is increasing demand for agricultural commodities that are produced in a climate-friendly manner. At the same time, in many or most tropical countries there is need for intensification of agricultural production to increase yields and incomes, and this usually requires higher external inputs that may cause additional greenhouse gas emissions. Here we investigate if production methods that have a beneficial effect on the climate (are climate-friendly) are compatible with increased inputs and yields for traditional, shaded cocoa (Theobroma cacao) production systems (locally known as cabrucas) in southern Bahia, Brazil. We use two easily measurable and manageable dimensions of climate friendliness, namely the carbon (C) stocks in the large trees and the C footprint as related to on-farm agrochemical and fuel use. Through interviews and field inventories in 26 cabruca farms representing a range of production practices and intensities, we identify the combinations of management practices, yields, C stocks and C footprints typically found in the region. We find that yield levels up to the highest encountered yield of 585 kg ha−1, or twice the current regional average of 285 kg ha−1, are compatible with an aboveground C stock in the large shade trees (>30 cm diameter at breast height) of up to 65 Mg ha−1 and up to 55 % shade. Higher C stocks and shade levels are generally associated with yields below the regional average. Input-related C emissions increased non-linearly with increasing yield, but even the highest encountered yields were compatible with low ( 1 kg CO2e kg−1 of cocoa) were related to large fertilizer applications that did not proportionately increase yields. We conclude that doubling the cocoa output from southern Bahia, where cabrucas are the predominant form of growing cocoa, is compatible with climate-friendly production practices, measured by local standards. We suggest that the presented methodology can be used to identify opportunities for climate-friendly intensification of tree crops more generally, thereby increasing the contribution of commodity production to global climate change mitigation.

Greenhouse Gas Emissions of Biomethane for Transport: Uncertainties and Allocation Methods

Employing a life-cycle assessment approach, this paper studies greenhouse gas (GHG) emissions resulting from biomethane used as transportation fuel. It focuses on both GHG allocation methodologies and uncertainties regarding GHG emissions from biomethane. The goal is to calculate GHG emissions of two types of biomethane used in transportation: that produced from biowaste feedstock and that extracted from dedicated energy crop feedstocks. The effects of allocation methods used for digestate and those of other factors arising during the life cycle of biomethane are studied. The GHG emissions of biomethane produced from biowaste with digestate use are approximately 22 gCO2eq MJ–1; those of biomethane extracted from dedicated energy crops are 61 gCO2eq MJ–1. However, using the substitution method for digestate decreases biowaste emissions by 10 gCO2eq MJ–1 and dedicated energy crop emissions by 22 gCO2eq MJ–1. The highest emissions uncertainties are related to land use change, cultivation processes, digestate use, and technology selections in digestion and upgrading. Using technology with high energy consumption or methane leakages will significantly increase total emissions. On the other hand, use of renewable energy in processes is one option for decreasing total emissions. It appears that biomethane could be produced with lower emissions than previous studies have shown by optimizing production and implementing new technology. The utilization of digestate in replacing mineral fertilizers, resulting in additional GHG emission reductions, is a key issue which should be accorded more attention in the future. For one to achieve reliable results, factors related to biomethane production and allocation methods for digestate emissions should always be chosen on a case-by-case basis.

Bioenergy prospects in Taiwan using set-aside land – an economic evaluation

Purpose – This study aims to explore Taiwan's potential for bioenergy production using feedstocks grown on set-aside land and discusses the consequent effects on Taiwan's energy security plus benefits and greenhouse gas (GHG) emission. Design/methodology/approach – The Modified Taiwan Agricultural Sector Model (Modified TASM), based on price endogenous mathematical programming, was used to simulate different agricultural policies related to bioenergy production. To do this simulation, the TASM model was extended to include additional bioenergy production possibilities and GHG accounting. Findings – Taiwan's bioenergy production portfolio depends on prices of ethanol, electricity and GHG. When GHG prices go up, ethanol production decreases and electricity production increases because of the relatively stronger GHG offset power of biopower. Originality/value – Taiwan is interested in producing bioenergy but only limited information is available. This study provides the information on potential bioethanol and bioelectricity production from various energy crops, GHG emission offset from bioenergy, and regional energy security.

A comparison of commercial ethanol production systems from Brazilian sugarcane and US corn

AbstractGlobal biofuels production grew rapidly from 2007 to 2012, led by the United States and Brazil, the world's two largest fuel‐ethanol‐producing systems. In this paper we provide insights into the characteristics of mature Brazilian sugarcane and maturing US dry mill corn ethanol industries. Both systems continue to improve as measured by life cycle data such as total renewable energy produced per unit of fossil energy consumed [renewable energy ratio (RER)]. Sugarcane self‐benchmarking systems showed RER values of 7.0 in 2002 to 9.4 in 2009 as the industry started to switch to mechanized harvesting. The average US RER improved from 1.1 to 1.7 from 2000 to 2010. RERs of 4.4 to 5.5 are observed in corn ethanol plants employing natural gas or corn stover combined heat and power. Ethanol systems configured to produce ethanol and electricity had similar net energy balances (a ratio of net energy produced to energy contained in the fuel). One measure of greenhouse gas (GHG) emissions reductions (biomass use efficiency) compares the effectiveness of displacing carbon from combustion of fossil fuels with renewable carbon. Advanced corn ethanol systems reach higher GHG emission reduction levels compared to sugarcane ethanol by displacing coal‐based electricity. Sugarcane systems achieve double the GHG emissions reductions per unit of harvested land relative to corn ethanol because sugarcane and corn are grown as perennial and annual crops in tropical and temperate climatic zones, respectively. Carbon dioxide capture and storage systems could offer additional GHG emission reductions for both corn and sugarcane ethanol systems. © 2013 Society of Chemical Industry and John Wiley & Sons, Ltd

Investigating the early Earth faint young Sun problem with a general circulation model

The faint young Sun problem, i.e. the contradiction of a reduced solar luminosity by 15–25% during the Archaean and the geological evidence for relatively high surface temperatures that allowed the presence of liquid water, is still mostly open. It is suggested that the cooling induced by a fainter Sun was e.g. offset by higher levels of greenhouse gases (GHGs) during the Archaean, but achieving the amounts of carbon dioxide (CO2) that are necessary to solve the problem can not be supported by proxy data and the estimates of other additional GHGs diverge.In our study we investigate this problem by using the climate model EMAC with a spectrally resolved irradiance dataset valid for the Archaean epoch of the Earth. Our experimental setup contains a series of model runs which allow the investigation of the role of the continents, the ozone and oxygen content of the atmosphere, the solar luminosity, and the CO2 concentration on the climate of the Archaean.Replacing the present day continents with a global ocean lead to a warming at the surface by ~3K and an intensified hydrological cycle. The generation of planetary waves and their propagation to the middle atmosphere is reduced, which intensifies the polar night jet and decelerates the Brewer–Dobson circulation. Slightly lower global annual mean temperatures can be found for an anoxic atmosphere. The absent ozone heating in the middle atmosphere leads to very low temperatures in the middle atmosphere and a vanishing polar night jet, whereas the subtropical jets and the Hadley circulation are intensified. The reduction of the solar luminosity to 82% of the present value leads to a globally ice-covered planet and very dry conditions. Prescribing 10 times the present atmospheric level of CO2 with the same solar luminosity leads to a broad belt of liquid surface water throughout the year, although the global annual mean temperature is below the freezing point of water. On reducing the solar luminosity to 77% of the present value with the same amount of CO2, the area of ice-free ocean water narrows, but still suggesting a habitable environment during the Archaean for a CO2 concentration consistent with paleosol data.

GHG reduction potential in waste management in Croatia

Purpose – The purpose of this paper is to examine a greenhouse gas (GHG) emission reduction potential from different waste management practices in Croatia. Energetic, environmental and economic benefits can be accomplished by utilizing municipal solid waste (MSW) and landfill gas as fuel in industry and energy sector, which is emphasized in this paper. The paper gives an overview of measures for energy recovery from MSW and landfill gas that could be implemented in Croatia. These measures also represent measures for an additional GHG emission reduction by decreased use of fossil fuels.Design/methodology/approach – A methodology used for emission calculation (kinetic model) is explained. Three different scenarios of GHG reduction in waste management were defined. Implementation of best available techniques in waste management is envisaged by cross‐sectoral impact and effect of respective measures. Findings –This paper gives maximum achievable potential of GHG emission reduction with defined measure impleme...