Net GHG Emissions Research Articles

Biojet fuel production from oleaginous crop residues: thermoeconomic, life cycle and flight performance analysis

This study assesses an integrated biorefinery model's efficiency for biojet fuel production as Jet A1 blending component through the Alcohol-to-Jet (ATJ) and Hydroprocessed Esters and Fatty Acids (HEFA) thermochemical routes, employing lignocellulosic biomass from oleaginous crops. The ATJ process involved cellulosic ethanol production through steam explosion hydrolysis, simultaneous saccharification and co-fermentation. The anhydrous ethanol was sequentially dehydrated, oligomerized, and hydrotreated. On the other hand, the HEFA process upgraded vegetable oil from residues and fatty acid distillates. The vegetable oil was thermally hydrolyzed, decarboxylated and hydrotreated. The models were simulated in AspenPlus® v.11, achieving a specific biojet fuel production of 48 wt% for the ATJ and 87 wt% for the HEFA. In both cases, a biojet fuel mixture primarily composed of C9 to C12 isoalkanes was produced. The minimum selling price ranged between 1.01 €/kg to 1.43 €/kg. The studied routes were evaluated through exergetic and thermoeconomic analyses for optimizing. The life cycle assessment was carried out in SimaPro® v.9.0. The estimated net GHG emissions were 75 gCO2eq/MJ for the ATJ and 18 gCO2eq/MJ for the HEFA; nevertheless, significant improvements were achieved from by-product displacement credits. In both cases, the GHG emissions are under those from petroleum-derived Jet A1 production. Finally, the physico-chemical properties fulfilled the ASTM D7566 specifications, and the calculated payload vs range showed a better performance for an intermediate-range flight.

An integrated assessment of environmental, economic, social and technological parameters of source separated and conventional sanitation concepts: A contribution to sustainability analysis

Resource recovery and reuse from domestic wastewater has become an important subject for the current development of sanitation technologies and infrastructures. Different technologies are available and combined into sanitation concepts, with different performances. This study provides a methodological approach to evaluate the sustainability of these sanitation concepts with focus on resource recovery and reuse. St. Eustatius, a small tropical island in the Caribbean, was used as a case study for the evaluation. Three source separation-community-on-site and two combined sewerage island-scale concepts were selected and compared in terms of environmental (net energy use, nutrient recovery/reuse, BOD/COD, pathogens, and GHG emission, land use), economic (CAPEX and OPEX), social cultural (acceptance, required competences and education), and technological (flexibility/adaptability, reliability/continuity of service) indicators. The best performing concept, is the application of Upflow Anaerobic Sludge Bed (UASB) and Trickling Filter (TF) at island level for combined domestic wastewater treatment with subsequent reuse in agriculture. Its overall average normalised score across the four categories (i.e., average of average per category) is about 15% (0.85) higher than the values of the remaining systems and with a score of 0.73 (conventional activated sludge – centralised level), 0.77 (UASB-septic tank (ST)), 0.76 (UASB-TF - community level), and 0.75 (ST - household level). The higher score of the UASB-TF at community level is mainly due to much better performance in the environmental and economic categories. In conclusion, the case study provides a methodological approach that can support urban planning and decision-making in selecting more sustainable sanitation concepts, allowing resource recovery and reuse in small island context or in other contexts.

Effect of globalization and climate change on forest – A review

Climate change, as a difficult that makes and is shaped by an overall sense of the globe, is sure up in each its assessment and its strategy proposition with comparable issues that defy globalization scholars. The multiplication of speculations and investigations in globalization and global climate change mirrors the rising idea of every territories of social logical idea. Forests and trees all through the globe are logically disappeared with factors related with global change. There is far less agreement on how such environmental change could influence the forests of the earth. The issue is basic since forests are a significant global wellspring of important market items specifically wood) just as ecological advantages (such species living space, biodiversity, and soil and atmosphere adjustment). Also, it is essential in view of the fact that throughout the following ten years, the new Kyoto Protocol needs significant decreases in net GHG emissions and gives “sink” credit just for cognizant human activities in forests that seize carbon. Considering global climate change and globalization along as a quest issue will light the edifices and methods of each. Notwithstanding, the appallingly detonation of thoughts and recommendations reflects the energy and personality to chase future guidelines which will bring amplified safety for every people and along these lines the setting.

Innovation with purpose

Innovation with purpose

Economic Impacts of Carbon Tax in a General Equilibrium Framework: Empirical Study of Japan

This study tries to find new insights of implementations of carbon tax policy as a suitable way to reach the long-term zero-carbon plan. This paper explores how carbon tax can affect the macroeconomy in Japan through the structural vector autoregression (S-VAR) technique conducted for the quarterly data throughout 2005–2020. A theoretical general equilibrium model backs the empirical analysis. The major findings reveal that any increase in energy price from the carbon tax will lead to an increase in interest rate, exchange rate, and consumer price index while there is a negative relationship between energy price increase from carbon tax and real gross domestic product (GDP) in Japan. Carbon Policy Refolution ([Formula: see text]), refunding carbon tax revenues, and adaptation of long-term policy of net zero GHG emissions by 2050 with the current situation of Japan’s power sectors are the major practical policies of this study.

Analysis of an Off-grid PV System for Disaster Mitigation Scheme in Remote Areas

The main objective of this paper is to present the techno-economic analysis of an off-grid Photovoltaic system, which prepared to support disaster mitigation scheme in remote areas. As a case study, a regency in Mentawai Island, Sumatera Barat is chosen to represent a remote area in a disaster-prone location. The proposed system capacity is 20 kWp PV system as a single electricity source for medical facility in the island. As a tool in this study, RETScreen software was used to analyze the technical, environmental, and economical feasibility analysis. As a base case scenario, the medical facility was supported by a diesel-fueled generator and the PV system can deliver 10.14 MWh of electricity to load annually. Net annual GHG emission reduction of the system is 19.4 ton of CO2 equivalent. With the total initial cost for the whole PV system at USD 41,380, RETScreen simulation result showed that the equity payback of the project is 6.0 years with IRR of 11.9% hence the project is financially viable.

Reducing climate impacts of beef production: A synthesis of life cycle assessments across management systems and global regions.

The global demand for beef is rapidly increasing (FAO, 2019), raising concern about climate change impacts (Clark et al., 2020; Leip et al., 2015; Springmann et al., 2018). Beef and dairy contribute over 70% of livestock greenhouse gas emissions (GHG), which collectively contribute ~6.3 Gt CO2‐eq/year (Gerber et al., 2013; Herrero et al., 2016) and account for 14%–18% of human GHG emissions (Friedlingstein et al., 2019; Gerber et al., 2013). The utility of beef GHG mitigation strategies, such as land‐based carbon (C) sequestration and increased production efficiency, are actively debated (Garnett et al., 2017). We compiled 292 local comparisons of “improved” versus “conventional” beef production systems across global regions, assessing net GHG emission data from Life Cycle Assessment (LCA) studies. Our results indicate that net beef GHG emissions could be reduced substantially via changes in management. Overall, a 46 % reduction in net GHG emissions per unit of beef was achieved at sites using carbon (C) sequestration management strategies on grazed lands, and an 8% reduction in net GHGs was achieved at sites using growth efficiency strategies. However, net‐zero emissions were only achieved in 2% of studies. Among regions, studies from Brazil had the greatest improvement, with management strategies for C sequestration and efficiency reducing beef GHG emissions by 57%. In the United States, C sequestration strategies reduced beef GHG emissions by over 100% (net‐zero emissions) in a few grazing systems, whereas efficiency strategies were not successful at reducing GHGs, possibly because of high baseline efficiency in the region. This meta‐analysis offers insight into pathways to substantially reduce beef production's global GHG emissions. Nonetheless, even if these improved land‐based and efficiency management strategies could be fully applied globally, the trajectory of growth in beef demand will likely more than offset GHG emissions reductions and lead to further warming unless there is also reduced beef consumption.

Simulation-based life cycle assessment of ferrochrome smelting technologies to determine environmental impacts

Decarbonization of metal production is currently a unique challenge for the industry. To gain insights, environmental impacts of ferrochrome smelting technologies were estimated using simulation-based life cycle assessment. Two leading technologies: (1) Steel Belt Sintering-Submerged Electric Arc Furnace (SBS-SAF), and (2) Rotary Kiln-Submerged Electric Arc Furnace (RK-SAF) were investigated. Four environmental impact categories: climate change, acidification, particulate matter, and resource use (minerals and metals), were considered. Results showed that GHG emissions for producing high carbon ferrochrome vary to a greater extent depending on location of processing plant because of differences in electricity emission factors. For example, South African energy grid generates more GHG emission than Finnish energy grid. Furthermore, though prereduction reduced SAF energy consumption, it did not necessarily result in reduced net GHG emissions due to high coal consumption of RK. Acidification and particulate matter were higher when using RK-SAF technology. Ferrochrome production generally had low impact on resource use.

Building performance indicators and IEQ assessment procedure for the next generation of EPC-s

In the current implementation of EPC-s, the assessment focus is purely on the energy consumption data. For the next generation of EPC-s, new performance indicators are proposed to address relevant building performance aspects, such as sustainability, productivity and market value. These indicators would enable evidence-based decision-making processes and facilitate the delivery of renovation triggers. Within the EPC framework, the problem is not the availability of such performance indicators, but the assessment effort required. Only easily available data can justifiably be introduced to bulk EPC-s, either as direct complementary input or as a performance indicator. Availability of such data was analysed from case studies that included EPC-s from 11 EU member states, mainly non-residential buildings. Analysed data included relevant HVAC information such as ventilation air flows, heating and cooling set-points and installed power, but also output data, such as EPC classes, net and primary energy need and GHG emissions. Based on our findings, we outlined two different development paths - one for existing buildings and one for new buildings and major renovations. Two categories of complementary indicators to energy are proposed – IEQ and power indicators.

Overview of Sustainable Aviation Fuels including emission of particulate matter and harmful gaseous exhaust gas compounds

Sustainable Aviation Fuels are one of the solutions to reduce emission of harmful gaseous exhaust gas compounds and particulate matter from aircraft engines. Alternative aviation fuels should do not contribute to climate change and should achieve net GHG emission throughout life cycle. By using a blend of certified alternative aviation fuel and conventional aviation fuel, the number and mass of emitted particles directly behind the aircraft can be reduced by 50 to 70% compared to pure conventional fuel. Currently, the ASTM D7566 standard allows seven methods of producing alternative aviation fuels, which include, among others, raw material from: biomass, algae, agricultural waste and animal or vegetable fats. The following article focuses on the raw materials for Sustainable Aviation Fuels, discuss generations of feedstock used in the production of alternative aviation fuels and describes requirements of aviation biofuels to be considered as ‘sustainable’. The article also reviews the emission researches of certified alternative aviation fuels in terms of gaseous exhaust gas compounds and particulate matter.

Integrated regional waste management to minimise the environmental footprints in circular economy transition

The building of new waste treatment plants has not been closely following the Circular Economy (CE) hierarchy, and the incurred cost and social acceptance have been challenging. Integrated regional waste management by waste trading can offer the sharing of resources to achieve a mutually beneficial system in CE transition. This study aims to minimise the environmental footprints, with the consideration of economic feasibility, in integrated regional waste management by developing an extended Pinch Analysis-based targeting method. The proposed graphical decision-support method is applied to a case study where the waste trading amongst Central Europe (Austria, the Czech Republic, Germany, Poland, and Slovakia) is considered. A monthly waste trading network is identified with Germany, and Austria serves as the country with a surplus of waste treatment capacity. The pessimistic estimation indicated that the GHG emission of the waste trading design is 0.311 t CO2eq/t of waste, where the GHG emission of 1 t waste is reduced by 20 kg – 30 kg compared to the baseline scenario. The assessment suggested that when the amount of waste to be transported by lorry is >5 t and the transport distance to the incineration plant compared to the landfill is less than ~500 – 940 km, waste trading for recovery offers a lower net GHG emission. However, to prevent pollution haven and to consider the economic feasibility, the landfill fees have to be increased significantly. The developed method can identify integrated waste management network for different levels of administrative division to minimise environmental footprints.

Technoeconomic and emissions evaluation of mobile in-woods biochar production

In-woods torrefaction of forest residues to produce biochar can sequester CO2 in long-lived products at potentially lower-cost and complexity than centralized biochar production. Yet there are major uncertainties around operations, cost, and emissions associated with in-woods processing. We present a technoeconomic and emissions analysis for mobile in-woods biochar production systems employing oxidative torrefaction, associated with a timber harvest in Jackson Demonstration State Forest (JDSF) of California as case study. Most of the processing site area is required for the pile of grinded slash feed and drying operations. Breakeven production costs for transport, processing, and application together range between 567 and 573 USD/ton biochar-C (equivalent to 392–341 USD/ton biochar). The dryer, if employed, and the reactor constitute the major portion of capital costs. Labor constitute the largest portion of operating costs, followed by tub grinder rental and biochar application within the forest soil. The requirement of a separate dryer can be relaxed for a mobile in-woods facility, as oxidative torrefaction provides the opportunity to process feedstock with relatively high moisture content (~50%). The respective net GHG emissions for two systems with and without dryer are 5.43 and 7.94 ton CO2 eq/ton biochar-C. However, when the emissions from natural decay of slash (if left unprocessed) are accounted as avoided emissions, the systems with and without dryer result in the respective GHG emission benefits of 6.61 and 4.85 ton CO2 eq/ton biochar-C. The systems reach their break-even point when CO2 emission benefits are valued at a minimum of 85.7–118.1 USD/ton CO2.

Effect and mechanism of biochar on CO2 and N2O emissions under different nitrogen fertilization gradient from an acidic soil

“Nature based solutions” has been proposed at COP25 as an important venture for combating anthropogenic climate change, and soil biochar amendment have been proposed to have vast carbon sequestration potential. On the other hand, biochar carbon storage in soils is confronted with both biochar and soil carbon and nitrogen loss. The superposition of these two influences leads to complex variation in net greenhouse gas emissions from biochar-amended-soils. Nitrogen fertilization is a common agriculture practice in China and worldwide. To study the effects and mechanisms of biochar on soil net greenhouse gas emissions (CO2, N2O) under different nitrogen fertilization gradient in a ferrallitic soil, a soil column experiment was conducted. Maize straw derived biochar (pyrolysed at 500 °C) and nitrogen fertilizer (ammonium sulfate) were investigated at varying application rates. It was found that biochar amendment increased CO2 emissions by 51.1%–57.1% and N2O emissions by 50.0%–73.7%, respectively, when soil was incubated with 50 mg N/kg nitrogen fertilization. The N2O emission in soil was dominated by nitrification, and the labile fraction of biochar played the dominant role in increasing soil CO2 and N2O emissions. Therefore, water or acid washing of biochar before its application would significantly reduce the net GHG emissions. When the nitrogen fertilization was applied at the unusually high level of 450 mg N/kg, the N2O emissions mainly came from denitrification. Biochar amendment introduced less soil CO2 emission increment, and suppressed N2O emissions by inhibition of denitrification via adsorption protection mechanism (towards nitrogen) and aeration effect. A chain mechanism has been illustrated and results from this study suggest that biochar is best applied to an environment or the circumstance that maximizes adsorption protection mechanism and aeration effect to achieve total greenhouse gas emission reduction. This study therefore provides basis for the scientific sound application and regulation of biochar amendment in soils.

Anaerobic membrane bioreactors (AnMBR) treating urban wastewater in mild climates

Feasibility of an AnMBR demonstration plant treating urban wastewater (UWW) at temperatures around 25–30 °C was assessed during a 350-day experimental period. The plant was fed with the effluent from the pre-treatment of a full-scale municipal WWTP, characterized by high COD and sulfate concentrations. Biodegradability of the UWW reached values up to 87%, although a portion of the biodegradable COD was consumed by sulfate reducing organisms. Effluent COD remained below effluent discharge limits, achieving COD removals above 90%. System operation resulted in a reduction of sludge production of 36–58% compared to theoretical aerobic sludge productions. The membranes were operated at gross transmembrane fluxes above 20 LMH maintaining low membrane fouling propensities for more than 250 days without chemical cleaning requirements. Thus, the system resulted in net positive energy productions and GHG emissions around zero. The results obtained confirm the feasibility of UWW treatment in AnMBR under mild and warm climates.

The LULUCF Regulation: the new role of land and forests in the EU climate and policy framework

The EU LULUCF Regulation, covering the land use and forestry sector, is an essential component of the EU 2030 climate and energy framework. The regulation’s key legal commitment, the no debit rule, requires that the sector does not produce net GHG emissions. All action taken within the sector should aim at maintaining, enhancing and strengthening sinks. The regulation creates a distinctive regulatory framework that provides member states with flexibility in the establishment of the reference levels reflecting sustainable forest management practices and their climate impacts. However, the regulation imposes a clear obligation to be progressive – in accordance with the global climate regime – in climate policies in relation to land and, in particular, forests.

Climate change mitigation for Australian wheat production

Climate change threatens humanity yet the provision of food that supports humanity is a major source of greenhouse gases, which exacerbates that threatening process. Developing strategies to reduce the emissions associated with key global commodities is essential to mitigate the impacts of climate change. To date, however, there have been no studies that have estimated the potential to reduce GHG emissions associated with the production of wheat, a key global commodity, at a national scale through changes to wheat production systems. Here, we assess the consequences for net GHG emissions of Australian wheat production from applying three changes to wheat production systems: increasing the rates of fertiliser N to achieve the water-limited yield potential; increasing the frequency of lime applications on acid soils; and changing a two year cropping rotation (from wheat-wheat to legume-wheat). We predict that applying these three changes across the key wheat growing regions in Australia would increase production of wheat and legumes by 17.8 and 5.3 Mt, respectively, over the two-year period. Intensifying Australian production would reduce the need to produce wheat and legumes elsewhere in the world. This would free up agricultural land at the global scale and avoid the need to convert forestland and grassland to cropping lands to meet increasing global demands for wheat. We find that applying these changes across wheat growing zones would reduce the GHGs associated with Australian wheat production by 18.4 Mt CO2-e over the two-year period. Our research supports the notion that intensification of existing agricultural production can provide climate change mitigation. The impacts of intensification on other environmental indicators also need to be considered by policy makers.

Gasification performance of torrefied Timothy hay and spruce wood chars in a CO2 environment

AbstractTimothy hay abundantly available in New Brunswick, Canada, is mostly used for animal feed and bedding. Upgrading biomass using Torrefaction method can offer benefits in its waste management, energy density and energy conversion efficiency. Temperature and residence time play an important role in the torrefaction process. Meanwhile, CO2 gasification is also a promising thermochemical conversion process due to its potential to reduce net GHG emissions and tune syngas composition. This study investigates the impact of torrefaction parameters on isothermal and non‐isothermal CO2 gasification of Timothy hay and spruce chars. Timothy hay chars exhibited higher CO2 gasification reactivity than chars from spruce. The physicochemical properties analysis indicated that higher reactivity of Timothy hay char was mainly attributed to the high amount of alkali and alkaline earth metal (AAEM) content, relatively large BET surface area, a high number ofactive sites, and a low crystalline index. Moreover, in both experimental cases, char derived through a high heating rate and high residence time conditions exhibited improved gasification performance, which was attributed to the generation of large amounts of AAEM (Ca and K) and high specific surface area. Co‐gasification results during non‐isothermal processes under CO2 showed the presence of larger interactions in coal char/Timothy hay char blends than that of coal char/spruce char blends. For both experimental conditions, interactions were enhanced once the char prepared from high heating rate and high residence time was gasified with coal char. Thus, the proposed approach is a sustainable way of conversion of Timothy hay under CO2 environment.

143 Impacts of soil carbon sequestration on life cycle greenhouse gas emissions in midwestern USA beef finishing systems

Abstract Using life cycle analysis (LCA), several studies have concluded that grass-finished beef systems have greater GHG intensities than feedlot-finished (FL) beef systems. These studies evaluated only one grazing management system– continuous grazing – and assumed steady-state soil carbon (C), to model the grass-finishing environmental impact. However, by managing for more optimal forage growth and recovery, adaptive multi-paddock (AMP) grazing can improve animal and forage productivity, potentially sequestering more soil organic carbon (SOC) than continuous grazing. To examine impacts of AMP grazing and related SOC sequestration on net GHG emissions, a comparative LCA was performed of two different beef finishing systems in the Upper Midwest, USA: AMP grazing and FL. We used on-farm data collected from the Michigan State University Lake City AgBioResearch Center for AMP grazing. Impact scope included GHG emissions from enteric methane, feed production and mineral supplement manufacture, manure, and on-farm energy use and transportation, as well as the potential C sink arising from SOC sequestration. Across-farm SOC data showed a 4-year C sequestration rate of 3.59 Mg C ha−1 yr−1 in AMP grazed pastures. After including SOC in the GHG footprint estimates, finishing emissions from the AMP system were reduced from 9.62 to −6.65 kg CO2-e kg carcass weight (CW)−1, whereas FL emissions increased slightly from 6.09 to 6.12 kg CO2-e kg CW−1 due to soil erosion. This indicates that AMP grazing has the potential to offset GHG emissions through soil C sequestration, and therefore the finishing phase could be a net C sink. However, FL production required only half as much land as AMP grazing. This research suggests that AMP grazing can contribute to climate change mitigation through SOC sequestration and challenges existing conclusions that only feedlot-intensification reduces the overall beef GHG footprint through greater productivity.

Simultaneous effects of biochar and nitrogen fertilization on nitrous oxide and methane emissions from paddy rice

Synthetic fertilizers are major agents of gaseous emissions including nitrous oxide (N2O), and rice cultivation is a primary source of methane (CH4) emission. Biochar (BC) addition to agricultural soils is a potential approach to mitigate N2O and CH4 emissions. This greenhouse study was conducted to assess the simultaneous effects of BC and nitrogen (N) fertilization to reduce N2O and CH4 emissions along with higher biomass accumulation in rice under controlled conditions. Nine treatment combinations of BC amendments at 0, 2 and 4% by weight (weight of BC/weight of soil) mixed into 3500 g of unsterile soil with 0, 70 and 140 kg N ha−1 were used in growing rice. Results show that BC-only treatments enhanced the volumetric water contents (VWC) by 9–14% and soil pH by 5–7% coupled with higher daily and cumulative seasonal CH4–C fluxes by 85–95% and 48–51%, respectively, compared with control treatment. Under 2% and 4% BC amendments, N at 140 kg ha−1 lowered the daily and cumulative seasonal CH4–C fluxes by 24–42% and 20–30%, respectively as compared to 70 kg N ha−1. Furthermore, BC amendments in N-treated soils reduced the daily and total seasonal N2O–N emissions by 27–67% and 49–61%, respectively, relative to N-only treatments. However, N addition in BC-amended soils showed 10–16% decreased VWC compared with the BC-only treated soils. In terms of rice growth, BC-only reduced the above- and below-ground biomass accumulation, delayed the tillering phase, and resulted in fewer vegetative tillers except for BC-treated pots with 140 kg N ha−1. Thus, this study suggests that the use of BC amendment at 2% with 140 kg N ha−1 may be a beneficial strategy to reduce the net GHG emissions from paddy rice in an Alfisol.

How much greenhouse gas can each global inhabitant emit while attaining the Paris Agreement temperature limit goal? The equity dilemma in sharing the global climate budget to 2100

Decisions taken under the Paris Agreement of the UNFCCC do not clarify how the principle of equity is to be operationalized. Proper consideration of different national circumstances is of paramount importance when designing any multilateral agreements, such as the Paris Agreement . Here, a methodology is presented that implements the equity principle in sharing the global climate budget among countries on the basis of their national circumstances identified by socio-economic factors such as the population size, the per-capita gross domestic product and the current net GHG emission, and physical factors such as the population density and the average temperature. The historical responsibility for net GHG emission since 1990 is dealt with by the financial commitments made by developed countries. The impact of international trade on actual net GHG emission associated with consumption of goods is deemed compensated by the carbon rights underlying the production of such traded goods. Results obtained show that without a consideration of national circumstances, large emitters can claim a larger quota. Nevertheless, national circumstances change over time because of social and economic development as well as because technological improvements. Consequently, quotas have to be recalculated over time (e.g. at each global stocktake).