Anaerobic Digestate Treatment Selection Model for Biogas Plant Costs and Emissions Reduction

Major US electric utility climate pledges have the potential to collectively reduce power sector emissions by one-third

Energy-related activities are a major contributor of greenhouse gas (GHG) emissions. A growing body of knowledge clearly depicts the links between human activities and climate change. Over the last century the burning of fossil fuels such as coal and oil and other human activities has released carbon dioxide (CO2) emissions and other heat-trapping GHG emissions into the atmosphere and thus increased the concentration of atmospheric CO2 emissions. The main human activities that emit CO2 emissions are (1) the combustion of fossil fuels to generate electricity, accounting for about 37% of total U.S. CO2 emissions and 31% of total U.S. GHG emissions in 2013, (2) the combustion of fossil fuels such as gasoline and diesel to transport people and goods, accounting for about 31% of total U.S. CO2 emissions and 26% of total U.S. GHG emissions in 2013, and (3) industrial processes such as the production and consumption of minerals and chemicals, accounting for about 15% of total U.S. CO2 emissions and 12% of total ...

This monograph is concerned with different aspects of green house gas (GHG) emissions in agriculture. The first part summarizes the total amount of GHG emissions and analyses them regarding their composition. A differentiation is made between the emissions which are already linked to agriculture (source group agriculture: digestion , manure-management and agricultural soils ) within the National Report on GHG Emissions and those which can be counted primarily in addition to agriculture ( energy and land use and land use change ). Depending on which database is used, agriculture is participating in emitting green house gases with 6.3% or 11.1% of total German GHG emissions in 2004. This means that agriculture is an important polluter. The development of GHG emissions in agriculture compared to the year 1990 is -18.5% for the source group agriculture. This means that the source group has reduced more emissions than the average (-17.5%) over all domains published within the National Report. Regarding the sources energy and land use and land use change in addition emission reduction is -16.4% in the same period and thus worse than the average. Moreover, realized emission reductions are predominantly based on structural changes, less on systematical measures. This fact raises the question how agriculture can make a contribution to the reduction of GHG emissions in future particularly with regard to higher aims in climate politics.For this reason the second part of the monograph identifies capacities for the reduction of GHG emissions by using available agricultural biomass for energetic purposes. Due to the heterogeneity of biomass and the variety of its possible products, a lot of technical processes concerning the conversion of biomass into energy exist in practice. Since all of them have different emission factors the derivation of realistic reduction capacities is a nontrivial problem. This work restricts the problem by combining existing biomass with those technologies which provide largest benefit concerning the reduction of GHG emissions. Thereby it is possible to evaluate the maximum contribution of GHG reductions from biomass usage in agriculture in Germany, which aggregates up to 50,341 Gg CO2-equivalent. This means that 78.3% of the emissions from the source group agriculture in 2004 could be compensated if biomass was used within those technologies which produce the largest benefit. In this regards the subsidy of energy crops in biogas plants based on the Erneuerbare Energien Gesetz (renewable energy law) in Germany should be reviewed because there they do not produce the largest benefit. Energy crops should be applied to replace solid fuels instead. Since in practice several biogas plants are already using energy crops as input material without having an option for alternatives, the question raises how this fact can be improved for the future regarding climate protection.Therefore the third part of this monograph analyses the possible emission reductions of different technologies for converting biogas into energy. Objects of investigation are existing technologies like block heat and power plants or direct gas feeding into public gas distribution system as well as future technologies like the application of biogas in different types of fuel cells. Although direct gas feeding has a better ratio concerning the conversion of primary to secondary energy the GHG reduction capacity is much less compared to technologies of cogeneration. The reason for this is that the production of electricity has much more effect on GHG emissions than the production of heat. This is to be seen when comparing the emission factors of certain reference systems used in this part like condensing boilers running with natural gas (253 gCO2/kWhheat), gas steam power plants (432 gCO2/kWhel) and the average emissions factor of German power production (653 gCO2/kWhel). The more electricity is produced by a conversion technology based on biogas, the higher is its GHG reduction capacity. Direct gas feeding is not the most efficient way of using biogas in matters of climate protection considering that only 13% of the natural gas in Germany is used for electric purposes and considering that replacing natural gas by biogas means that the part of fossil fuels with lowest emissions is replaced. Direct gas feeding is not even then the most efficient way of using biogas if there is a consumer at the other end of the public gas distribution system who theoretically uses the injected biogas for running cogeneration systems. The conditioning of biogas in order to feed public distribution combined with additional heat source for running the fermenter of the biogas plant is worse for efficiency. Considering ecological standpoints local heat and power production next to the fermenter is the most efficient way of using biogas in matters of climate protection. This can only be improved by using more efficient systems like fuel cells instead of existing block heat and power plants.

Aktualnie ważnym wyzwaniem dla sektora rolniczego jest redukcja emisji gazów cieplarnianych (GHG) w celu złagodzenia skutków zmian klimatycznych. Istnieje potrzeba dokładnej identyfikacji źródeł emisji oraz upowszechnienia praktyk rolniczych, które przyczyniałyby się do zmniejszenia emisji we wszystkich ogniwach produkcji roślinnej. Do przeprowadzenia obiektywnych porównań i wyboru najlepszych rozwiązań technologicznych według kryterium emisyjności potrzebna jest szczegółowa ocena ilościowa emisji GHG. W opracowaniu przedstawiono ocenę emisji GHG w produkcji roślinnej za pomocą śladu węglowego (CF). Udział operacji technologicznych w powstawaniu CF scharakteryzowano na przykładzie rzepaku ozimego. Wyniki badań wskazują, że największe znaczenie w kształtowaniu CF ma proces nawożenia mineralnego. Wpływ pozostałych procesów na CF jest wielokrotnie mniejszy. Miejscem głównych emisji GHG w nawożeniu mineralnym rzepaku są emisje bezpośrednie i pośrednie GHG z pól. Po emisjach GHG z pól, produkcja nawozów stanowi drugie źródło emisji z nawożenia. Zmiany praktyk rolniczych polegających na zwiększeniu efektywności nawożenia azotowego oraz stosowaniu nawozów o niskich współczynnikach emisji stwarzają obecnie możliwość redukcji emisji GHG i przez to, tym samym mogą przyczynić się do zmniejszenia CF produktów roślinnych.

Mitigating Curtailment and Carbon Emissions through Load Migration between Data Centers

Greenhouse gas (GHG) emissions reduction in the electricity sector: Implications of increasing renewable energy penetration in Ghana's electricity generation mix

ABSTRACTSludge is an important source of greenhouse gas (GHG) emissions, both in the form of direct process emissions and as a result of indirect carbon-derived energy consumption during processing. In this study, the carbon budgets of two sludge disposal processes at two well-known sludge disposal sites in China (for biodrying and heat-drying pretreatments, both followed by mono-incineration) were quantified and compared. Total GHG emissions from heat drying combined with mono-incineration was 0.1731 tCO2e t−1, while 0.0882 tCO2e t−1 was emitted from biodrying combined with mono-incineration. Based on these findings, a significant reduction (approximately 50%) in total GHG emissions was obtained by biodrying instead of heat drying prior to sludge incineration.Implications: Sludge treatment results in direct and indirect greenhouse gas (GHG) emissions. Moisture reduction followed by incineration is commonly used to dispose of sludge in China; however, few studies have compared the effects of different drying pretreatment options on GHG emissions during such processes. Therefore, in this study, the carbon budgets of sludge incineration were analyzed and compared following different pretreatment drying technologies (biodrying and heat drying). The results indicate that biodrying combined with incineration generated approximately half of the GHG emissions compared to heat drying followed by incineration. Accordingly, biodrying may represent a more environment-friendly sludge pretreatment prior to incineration.

Harmonizing the quantification of CCS GHG emission reductions through oil and natural gas industry project guidelines

Since the beginning of the 19th Century, the natural environment of the planet has been placed under the dire threat of climate change. That has been caused by greenhouse gas (GHG) emissions from the burning of fossil fuels. GHG emissions threaten to alter the planets ecosystems disastrously and permanently. Statistics reveal that Australian individuals are among the highest GHG emitters on the planet and the transport sector contributes nearly one-fifth of the nation’s GHG emissions. It suggests that significant reductions in Australian GHG emissions are urgently required, and it is considered that those reductions might be helped by transitioning to electric vehicles (EVs) in the transport sector. This paper looks at the consumption of motor vehicle fuels in Australia’s transport sector and suggests how a reduction in GHG emissions might be achieved. It suggests that electrification of Australian motor vehicles could eliminate up to 20 per cent of existing Australian GHG emissions. The paper presents further findings of a case study that was conducted on a Mitsubishi Outlander Plug-in Electric Hybrid (PHEV) in remote Western Australia from 2016-17. That research is updated and extended in this paper to October 2021. It further considers published statistical data from the Organisation for Economic Co-operation and Development (OECD) and Australian government agencies to support its findings, conclusions and suggestions for further research. It looks at the rate of transition towards electrification of Australian roadways and concludes that while the transport sector’s growing contribution to Australia’s overall GHG emissions could be significantly reduced by the transition to electric vehicles, it has a way to go. The paper suggests that there are significant economic factors that are inhibiting the adoption of electric vehicles in Australia. However, rising fuel prices could encourage the transition away from the environmentally damaging internal combustion engine powered vehicles towards the electrification of the transport sector in Australia.

For all its cachet, you might think that hybrid drivetrain technology is inherently green. But only 13 of 34 hybrid vehicles assessed achieve better than a 25% reduction in greenhouse gas (GHG) emissions, and just 3 exceed a 40% reduction, according to an evaluation by the Union of Concerned Scientists (UCS).1 Moreover, reductions in GHG emissions do not necessarily correlate with reductions in other toxic emissions. Like any engine output–improving technology, hybrid technology can boost both fuel efficiency and power—but the more you boost one, the less you can boost the other. That dichotomy spurred the UCS to develop its “hybrid scorecard,” which rates each hybrid according to how well it lives up to its promise of reducing air pollution.2 All the vehicles were from model year 2011 except for one, the 2012 Infiniti M Hybrid. First the UCS scored each hybrid on how much it reduced its GHG emissions relative to its conventional counterpart, on a scale of zero (least reduction) to 10 (greatest reduction). These scores reflect the percentage in fuel efficiency gain. For example, the Toyota Prius gets 50 mpg3 compared with 28 mpg for the comparable Toyota Matrix. This represents a 44.0% reduction in GHG emissions, earning the Prius a GHG score of 9.4. At the bottom of the scale, the 21-mpg hybrid VW Touareg reduces GHG emissions only 10% over the 19-mpg conventional Toureg, for a score of 0.0. With a 46% improvement, the luxury Lincoln MKZ Hybrid had the greatest reduction over its conventional counterpart. The UCS also scored hybrids for absolute emissions (rather than relative to the conventional model) of air pollutants including particulate matter, carbon monoxide, hydrocarbons, and nitrogen oxides. These scores, on a scale of zero (dirtiest) to 10 (cleanest), are based on California certifications for tailpipe emissions. As the scorecard showed, a vehicle that emits less heat-trapping gases may not necessarily emit less of other air pollutants. For example, the Mercedes Benz S400 Hybrid scored 9 on air pollution reduction, alongside the Prius and the Lincoln MKZ, but only 1.3 on GHG emissions. HYBRID SCORECARD: Top 10 Nonluxury Hybrids by Total Environmental Improvement Score “Hybrid technology doesn’t add additional challenges [to reducing exhaust pollutants] that can’t be addressed through design of the vehicle’s emission controls,” says Don Anair, senior vehicles analyst at the UCS. “Numerous manufacturers of hybrids are meeting the lowest emissions levels. Hybrid manufacturers who aren’t delivering the lowest smog-forming emissions have chosen not to do so.” Each vehicle’s air pollution and GHG scores were averaged into a total “environmental improvement score,” again with the MKZ and the Prius leading the pack, and the Touareg scraping bottom. The UCS also scored “hybrid value” (the cost of reducing GHG emissions in dollars per percent reduction) and “forced features” (options you must buy with the hybrid whether you want them or not). HYBRID SCORECARD: Top 10 Luxury Hybrids by Total Environmental Improvement Score Luke Tonachel, vehicles analyst with the Natural Resources Defense Council, compliments the scorecard for illustrating that hybrid technology is not automatically green. He says, “We should improve the efficiency of all vehicles, and [hybrid technology] is just one technology that can get us there if applied with that goal in mind.” Nonetheless, Jamie Kitman, the New York bureau chief for Automobile Magazine, questions the wisdom of emphasizing percentage improvement in gas mileage rather than absolute miles per gallon. At 21 mpg, the hybrid Cadillac Escalade 4WD represents a 29% improvement over the 15-mpg conventional model, saving nearly 2 gallons per 100 miles. But the hybrid Escalade is still a gas guzzler, and Kitman says he wishes people would see through the marketing that encourages them to buy SUVs and “crossovers” rather than ordinary cars, which are more efficient than either. Says Anair, “The scorecard shows that automakers can pair hybrid technology with advanced emission controls to help tackle climate change while reducing the health impacts from breathing polluted air.” However, he adds, alluding to the stark variation in how much hybrid technology boosted fuel efficiency, “Not all automakers are delivering on the full promise of this technology.”

This study was conducted to provide low carbon farming technique for greenhouse gases(GHGs) emission reduction in agriculture sector. It reviewed literatures on the characteristic of cultivation technique and its effects on carbon emission reduction. The effects of GHGs emission reduction were evaluated in agricultural land with several farming practices. In the rice cultivation technique, the irrigation water management showed good effect on GHGs emission reduction in paddy field. It also evaluated reduction efficiency of source of nitrogen supply and soil improvement. The intermittent irrigation showed 25.1% carbon reduction efficiency as compared to continuously flooded treatment. Slow release fertilizer and ammonium sulphate decreased carbon emission by 19.8% and 7.9% compared to urea, respectively. With soil amendments treatment, silicate fertilizer and zeolite reduced carbon emission 14.1% and 21.7% compared to rice straw treatment. In the upland crop cultivation technique, the efficiency of tillage management, green manure, livestock compost and nitrification inhibitor application were estimated. Substitution of 50% of nitrogen with hairy vetch showed 65.6% carbon reduction efficiency. It also showed 20.4% emission reduction with nitrification inhibitor treatment. However, GHGs emission were increased with livestock compost application. It provided basic data for reducing the GHGs emission in agriculture sector by accomplishing low carbon farming technique and policy project. Effect of farming practices on GHG emission reduction in paddy field.

This research aims to assess the greenhouse gas (GHG) emissions reductions due to the use of biogas technology in Quang Tri Province. With a total of over 354,000 cattle in Quang Tri Province, Vietnam, waste from livestock becomes large. The GHG emitted from the livestock industry is not small, affecting the environment. Currently, there is little concern or documentation about the reduction of GHG emissions in small farms using biogas digesters in central Vietnam. This province has applied technological solutions, typically biogas digesters, but the amount of biogas production is not calculated accurately. Our survey was conducted in Vinh Linh District and Cam Lo District in March 2019 and involved 50 farms equipped with biogas digesters and 20 farms without it. The respondents were selected based on the information provided by local authorities, satisfying two conditions: livestock households and biogas users. The former group was asked 25 questions and the latter was asked 10 questions needed to calculate GHG emissions such as the number of animals and petroleum gas/ firewood consumption. This study uses formulas described in the 2006 guideline issued by IPCC to estimate reduced GHG emissions. The results showed that the average biogas production is 5.52 m³.household-1.day-1. Only 2% of the farms made the best use of the biogas digester. The surveyed households have not really used the most optimal amount of biogas production. In this scenario, this study recommends some solutions for solving the problem. In addition, the average annual emissions before having a biogas digester are estimated to be 20.53 tons CO2e/household/year. After using the biogas, the GHG emissions are reduced to 4.52 tCO2e.household-1.day-1. Thus, the replacement of daily cooking energies with biogas helps reduce 16.01 tCO2e of greenhouse gas for each farm per year.

The dairy Carbon Offset Scenario Tool (COST) was developed to explore the influence of various abatement strategies on greenhouse gas (GHG) emissions for Australian dairy farms. COST is a static spreadsheet-based tool that uses Australian GHG inventory methodologies, algorithms and emission factors to estimate carbon dioxide, methane and nitrous oxide emissions of a dairy farm system. One of the key differences between COST and other inventory-based dairy GHG emissions calculators is the ability to explore the effect of reducing total farm emissions on farm income, assuming the strategy was compliant with Kyoto rules for carbon offsets. COST provides ten abatement strategies across the four broad theme areas of diet manipulation, herd and breeding management, feedbase management and waste management. Each abatement strategy contains four sections; two sections for data entry (baseline farm data specific to the strategy explored and strategy-specific variables) and two sections for results (milk production results and GHG/economic-related results). Key sensitive variables for each strategy, identified from prior research, and prices for milk production and carbon offsets are adjusted through up/down buttons, which allows users to quickly explore the impact of these variables on farm emissions and profitability. For example, if the cost to implement an abatement strategy is doubled, what carbon offset income would be required to negate this additional cost? Results are presented as changes in carbon offset income, strategy implementation cost, additional milk production income and net farm income on a per annum and on a per GHG emissions intensity of milk production basis. COST currently contains a comprehensive range of strategies for GHG abatement, although some strategies are still in development. As new technologies or farm management practices leading to a reduction in GHG emission become available, these too will be incorporated into COST. To date, two dairy-specific abatement methodologies have been legislated as part of Australia’s commitment to reducing on-farm GHG emissions through it’s the carbon offset scheme, the Carbon Farming Initiative (CFI) and are incorporated into COST. These are the ‘Destruction of methane generated from dairy manure in covered anaerobic ponds’ and the ‘Methodology for reducing greenhouse gas emissions in milking cows through feeding dietary additives’. As an example, we explored the mitigation option Replace supplements with a source of dietary fats (reflecting the second above-mentioned CFI legislated abatement strategy) as feeding a diet higher in dietary fats has been shown to reduce enteric methane emissions per unit of feed intake. A 400 milking herd was fed a baseline diet of 2.6% dietary fat. By replacing grain with hominy meal, at a rate of 5.0 kg dry matter/ cow per day for 90 days during the 3 summer months, the summer diet fat concentration was increased to 6.4%. Enteric methane emissions were reduced by 40 tonnes of carbon dioxide equivalents (t CO 2 e) per annum for the farm. Waste methane and nitrous oxide emissions were also reduced by 0.5 and 1.6 t CO 2 e/annum, respectively. However, as reductions from these two sources of GHG emissions do not qualify for payment with this CFI methodology, their reduction could not be included as an offset income. At a carbon price of $20/ t CO 2 e, the reduction in enteric methane emissions was valued at $800/farm. The implementation cost of replacing grain with hominy was valued at $18,000/farm due to the hominy meal costing an additional $100/t dry matter compared to the grain. However, the additional milk production achieved due to the higher energy concentration of the diet resulted in an additional 70,200 litres and based on a summer milk price of $0.38/ litre, this equated to an additional income from milk valued at $26,676/farm. The overall result was a net increase in farm profit of $9,476/farm when paid on a reduction in total GHG emissions. COST can quickly allow users to ascertain the level of GHG emission reduction possible with various mitigation options and explore the sensitivity of key variables on GHG emissions and farm profitability.

Simple SummaryLivestock accounts for an estimated 80% of total agricultural greenhouse gas emissions, making abatement of greenhouse gas emissions from livestock a high-priority challenge facing animal nutritionists. Mitigating greenhouse gases in ruminants without reducing animal production is desirable both as a strategy to reduce global greenhouse gas emissions and as a way of improving dietary feed efficiency. The inclusion of feed additives in the diets of ruminants can reduce energy losses as methane, which typically reduces animal performance and contributes to greenhouse gas emissions. The present study evaluated the abatement potential of nine essential oil blends to mitigate greenhouse gas emissions. The inclusion of the blends resulted in a reduction in greenhouse gas emissions and in vitro apparent dry matter digestibility with higher values noted for the control treatment. A similar trend was noted for in vitro truly dry matter digestibility with higher values noted in the control treatment. The efficiency of microbial production was greater for the blends. The inclusion of the blends affected the total and molar proportion of volatile fatty acid concentrations. Overall, inclusion of the blends modified the rumen function resulting in improved efficiency of microbial production.The current study evaluated nine essential oil blends (EOBs) for their effects on ruminal in vitro dry matter digestibility (IVDMD), efficiency of microbial production, total short-chain fatty acid concentration (SCFA), total gas, and greenhouse gas (GHG) emissions using two dietary substrates (high forage and high concentrate). The study was arranged as a 2 × 2 × 9 + 1 factorial design to evaluate the effects of the nine EOBs on the two dietary substrates at two time points (6 and 24 h). The inclusion levels of the EOBs were 0 µL (control) and 100 µL with three laboratory replicates. Substrate × EOBs × time interactions were not significant (p > 0.05) for total gas and greenhouse gas emissions. The inclusion of EOBs in the diets resulted in a reduction (p < 0.001) in GHG emissions, except for EOB1 and EOB8 in the high concentrate diet at 6 h and for EOB8 in the high forage diet at 24 h of incubation. Diet type had no effect on apparent IVDMD (IVADMD) whereas the inclusion of EOBs reduced (p < 0.05) IVADMD with higher values noted for the control treatment. The efficiency of microbial production was greater (p < 0.001) for EOB treatments except for EOB1 inclusion in the high forage diet. The inclusion of EOBs affected (p < 0.001) the total and molar proportion of volatile fatty acid concentrations. Overall, the inclusion of the EOBs modified the rumen function resulting in improved efficiency of microbial production. Both the apparent and truly degraded DM was reduced in the EOB treatments. The inclusion of EOBs also resulted in reduced GHG emissions in both diets, except for EOB8 in the high forage diet which was slightly higher than the control treatment.

In Malaysia, the greenhouse gases (GHGs) emissions reduction via composting of source-separated organic waste (SOW) in municipal solid waste (MSW) has not been assessed. Assessment of GHG emissions reduction via composting of SOW is important as environmental impacts from waste management are waste-specific and local-specific. The study presents the case study for potential carbon reduction via composting of SOW in University of Malaya (UM). In this study, a series of calculations were used to evaluate the GHG emission of different SOW management scenarios. The calculations based on IPCC calculation methods (AM0025) include GHGs emissions from landfilling, fuel consumption in transportation and SOW composting activity. The methods were applied to assess the GHG emissions from five alternative SOW management scenarios in UM. From the baseline scenario (S0), a total of 1,636.18 tCO(2e) was generated. In conjunction with target of 22 recycling rate, as shown in S1, 14 reduction in potential GHG emission can be achieved. The carbon reduction can be further enhanced by increasing the SOW composting capacity. The net GHG emission for S1, S2, S3 and S4 were 1,399.52, 1,161.29, 857.70 and 1,060.48 tCO(2e), respectively. In general, waste diversion for composting proved a significant net GHG emission reduction as shown in S3 (47), S4 (35) and S2 (29). Despite the emission due to direct on-site activity, the significant reduction in methane generation at landfill has reduced the net GHG emission. The emission source of each scenario was studied and analysed.