Greenhouse Gas Emission Reduction Benefits Research Articles

Long-term microgrid expansion planning with resilience and environmental benefits using deep reinforcement learning

Microgrid plays an increasingly important role to enhance power resilience and environmental protection regarding greenhouse gas emission reduction through the widespread applications of distributed and renewable energy. Because of the steady growth of load demand, the strict power resilience requirements and the pressing need of carbon emission reduction, microgrid expansion planning considering those factors has become a currently topical topic. In this study, a new framework for long-term microgrid expansion planning, in which a microgrid serves as a backup power system in the event of main grid outages from the perspectives of economy, resilience and greenhouse gas emission, is proposed. Deep reinforcement learning method is used to solve this dynamic and stochastic optimization problem by taking into account various uncertainties and constraints for the long-range planning. Case studies of 20-year microgrid expansion planning using actual data are conducted. The simulation results demonstrate the effectiveness of the proposed framework on reducing greenhouse gas emissions and total cost including economic losses resulting from power grid outages, investment and operating cost of microgrid entities. In addition, the impact of customer load demand and microgrid entities price on optimal planning policies is discussed. The results demonstrate that microgrid expansion planning can be effectively adapted to different levels of load demand and different scenarios of price changes under the proposed framework. This work is helpful for decision makers to implement cost-effective and power resilient microgrid expansion planning with greenhouse gas emission reduction benefits in the long term.

Can shared micromobility programs reduce greenhouse gas emissions: Evidence from urban transportation big data

Shared micromobillity has been extensively developed globally in the past few decades, but its impact on the environment remains unclear. This study quantitatively estimates the effects of global shared micromobillity programs on greenhouse gas (GHG) emissions using a life cycle assessment (LCA) perspective. Specifically, it takes major countries and cities around the world as examples to empirically analyze the impact of station-based bike-sharing (SBBS), free-floating bike-sharing (FFBS), free-floating e-bike sharing (FFEBS), and free-floating e-scooter sharing (FFESS) programs on the GHG emissions of urban transportation. The results show that, with the exception of SBBS, the other shared micromobillity programs have not achieved desirable GHG emissions reduction benefits. Contrarily to subjective expectations, although the rapid progress of technology in recent years has promoted the vigorous development of shared micromobility, it has brought negative impacts on the GHG emissions rather than the positive benefits claimed by related promoters and operators. The overcommercialization and low utilization rate makes shared micromobility more likely to be an environmentally-unfriendly mode of transportation. In addition, the regional differences in mode choice, operational efficiency, fleet scale, and market potential of shared micromobility and the corresponding impacts on GHG emissions vary greatly. Therefore, authorities should formulate appropriate shared micromobility plans based on the current conditions and goals of the region. This empirical study helps to better understand the environmental impact of the global shared micromobility program and offers valuable references for improving urban sustainability.

A Study for Development Suitability of Biomass Power Generation Technology Based on GHG Emission Reduction Benefits and Growth Potential.

Biomass energy can alleviate global warming and solve energy depletion, which is increasingly concerned by the world. Due to the different emission reduction benefits and growth potential of different regions and biomass power generation technologies, analyzing the suitability of these technologies combined with regional conditions can more accurately guide the long- and short-term development of biomass power industry. However, there is no comprehensive evaluation of the benefits and potential of several biomass power generation technologies in different regions. Therefore, this paper introduces development suitability indexes and constructs life-cycle environmental impact and time-value economic impact assessment models, and a growth potential dynamic assessment model based on Gaussian process and particle swarm optimization to illustrate the greenhouse gas emission reduction benefits and growth potential of biomass power generation technologies. The empirical research of China shows that biomass gasification and direct combustion power generation can bring the best environmental benefits, and biogas power generation can bring the best economic benefits. For regions with abundant biomass resources and bad air condition, it is more suitable to develop gasification and direct combustion power generation technology, while mixed-combustion and biogas power generation technology are more suitable in regions with high electricity consumption.

Monetary Health Co-Benefits and GHG Emissions Reduction Benefits: Contribution from Private On-the-Road Transport.

This is the first study to provide a systematic monetary benefit matrix, including greenhouse gas (GHG) emissions reduction benefits and air pollution reduction health co-benefits, for a change in on-the-road transport to low-carbon types. The benefit transfer method is employed to estimate the social cost of carbon and the health co-benefits via impact pathway analysis in Taiwan. Specifically, the total emissions reduction benefits from changing all internal combustion vehicles to either hybrid electric vehicles, plug-in hybrid electric vehicles, or electric vehicles would generate an average of USD 760 million from GHG emissions reduction and USD 2091 million from health co-benefits based on air pollution reduction, for a total benefit of USD 2851 million annually. For a change from combustion scooters to light- or heavy-duty electric scooters, the average GHG emissions reduction benefits would be USD 96.02 million, and the health co-benefits from air pollution reduction would be USD 1008.83 million, for total benefits of USD 1104.85 million annually.

Mitigating Curtailment and Carbon Emissions through Load Migration between Data Centers

Summary As the share of variable renewable energy (VRE) grows in the electric grid, so does the risk of curtailment. While energy storage and hydrogen production have been proposed as solutions to the curtailment problem, they often pose technological and economic challenges. Here, we analyze the potential of data center load migration for mitigating curtailment and greenhouse gas (GHG) emissions. Using historical hourly electricity generation, curtailment, and typical data center server utilization data, we simulate the effect of migrating data center workloads from the fossil-fuel-heavy PJM to the renewable-heavy CAISO. The results show that load migration within the existing data center capacity during the curtailment hours in CAISO has the potential to reduce 113–239 KtCO2e per year of GHG emissions and absorb up to 62% of the total curtailment with negative abatement costs in 2019. Our study demonstrates the overlooked role that data centers can play for VRE integration and GHG emissions mitigation.

Greenhouse Gas Emission Analysis of Biomass Moving-bed Pyrolytic Polygeneration Systems based on Aspen Plus and Hybrid LCA in China

Under the existing scenario of greenhouse gas (GHG) emission reduction technologies, it is difficult to make the global temperature rise within 2°C in 2100. Thus, bio-energy with carbon capture and storage (BECCS) technology, as one of primary negative carbon emission methods, is urgent to deploy. In order to correctly recognize the development potential of bio-energy, the biomass pyrolytic polygeneration system, as the second novel bio-energy technology, should be carefully investigated in terms of GHG emission intensity and GHG emission reduction firstly. In this study, the material and energy flow in the process was carefully studied, and its environmental benefits was further researched. Based on the biomass pyrolysis mechanism and components pyrolysis property, the model of biomass pyrolytic polygeneration system was built on the Aspen Plus simulator, which is used to make an analysis of the life cycle greenhouse gas emission reduction. Results indicated that the agriculture process as the largest contributor to total GHG emissions with 86.03% of the total plant GHG emissions. In the entire pyrolysis temperature range, the intensity of GHG emissions from moving bed pyrolytic polygeneration system is from 4.15 to 6.12 g CO2-eq/MJ. Compared with other pyrolysis products, bio-char has a greater impact on the GHG emission reduction benefits of pyrolytic system. For the same system capacity, the system has the largest emissions reduction at a reaction temperature of 250°C, where also the bio-char yields is largest. If all of the bio-char returns to the field, the system can lead to negative carbon emission, which is 22 times larger than the system GHG emission when pyrolysis temperature is 250°C.

Petroleum substitution, greenhouse gas emissions reduction and environmental benefits from the development of natural gas vehicles in China

This study develops a bottom-up model to quantitatively assess the comprehensive effects of replacing traditional petroleum-powered vehicles with natural gas vehicles (NGVs) in China based on an investigation of the direct energy consumption and critical air pollutant (CAP) emission intensity, life-cycle energy use and greenhouse gas (GHG) emission intensity of NGV fleets. The results indicate that, on average, there are no net energy savings from replacing a traditional fuel vehicle with an NGV. Interestingly, an NGV results in significant reductions in direct CAP and life-cycle GHG emissions compared to those of a traditional fuel vehicle, ranging from 61% to 76% and 12% to 29%, respectively. Due to the increasing use of natural gas as a vehicle fuel in China (i.e. approximately 28.2 billion cubic metres of natural gas in 2015), the total petroleum substituted with natural gas was approximately 23.8 million tonnes (Mt), which generated a GHG emission reduction of 16.9 Mt of CO2 equivalent and a CAP emission reduction of 1.8 Mt in 2015. Given the significant contribution of NGVs, growing the NGV population in 2020 will further increase the petroleum substitution benefits and CAP and GHG emission reduction benefits by approximately 42.5 Mt of petroleum-based fuel, 3.1 Mt of CAPs and 28.0 Mt of GHGs. By 2030, these benefits will reach 81.5 Mt of traditional petroleum fuel, 5.6 Mt of CAPs and 50.5 Mt of GHGs, respectively.

Impact of Co-firing Straw for Power Generation to Air Quality: A Case Study in Two Coal Power Plants in Vietnam

Open field burning of rice straw regularly contributes to severe air quality issues affecting millions of inhabitants in the city of Ha Noi. We examine how much replacing open field burning by co-firing mitigates local air pollutants and greenhouse gases emissions. We select two coal power plants located in the North of Vietnam as specific examples. Our findings show that co-firing straw in these plants at 5% mixing ratio on heat basis can reduce greenhouse gas emission as well as air pollutant emissions (SO2, PM10 and NOx) from 3% up to 13%. We examined the social value of these emission reductions using external costs factors. The health benefits of improving air quality by disposing of straw at a large coal power plant instead of open field burning are over ten million USD per year. This is the same order of magnitude as the technical costs of co-firing. Greenhouse gas emissions reduction benefits appear smaller.

Life cycle greenhouse gas emissions of hydrogen fuel production from chlor-alkali processes in the United States

By-product hydrogen from chlor-alkali processes can help meet the increasing demand for hydrogen fuel in early fuel cell electric vehicle markets (e.g., California) in the U.S. Hydrogen produced from chlor-alkali plants is typically combusted for process heat on site, vented to the atmosphere (i.e., wasted), or sold to the external merchant hydrogen market. Whether it is combusted, vented, or sold as a commodity, relevant information is lacking as to the life-cycle environmental benefits or trade-offs of using by-product hydrogen from chlor-alkali plants. A life-cycle analysis framework was employed to evaluate well-to-gate greenhouse gas (GHG) emissions associated with by-product hydrogen from chlor-alkali processes in comparison with hydrogen from the conventional centralized natural gas steam methane reforming (central SMR) pathway. U.S.-specific, plant-by-plant, and up-to-date chlor-alkali production characteristics were incorporated into the analysis. In addition to the venting and combustion scenarios, to deal with the multi-functionality of the chlor-alkali processes that simultaneously produce chlorine, sodium hydroxide, and hydrogen, two different co-product allocation strategies were adopted—mass allocation and market value allocation. It was estimated that by-product hydrogen production from chlor-alkali processes creates 1.3–9.8 kg CO2e/kg H2 of life-cycle GHG emissions on average, which is 20–90% less than the conventional central SMR pathway. The results vary with co-product treatment scenarios, regional electric grid characteristics, on-site power generation, product prices, and hydrogen yield. Despite the variations in the results, it was concluded that the life-cycle GHG emission reduction benefits of using by-product hydrogen from chlor-alkali processes are robust. With a diverse set of scenario analyses, the study developed a comprehensive and detailed life-cycle GHG emissions inventory of the chlor-alkali by-product hydrogen pathway and quantified sensitivity indices in the context of different assumptions and input parameter values.

Costs and benefits of biogas recovery from communal anaerobic digesters treating domestic wastewater: Evidence from peri-urban Zambia

Communal anaerobic digesters (ADs) have been promoted as a waste-to-energy strategy that can provide sanitation and clean energy co-benefits. However, little empirical evidence is available regarding the performance of such systems in field conditions. This study assesses the wastewater treatment efficiency, energy production, greenhouse gas (GHG) emissions, and financial costs and benefits of communal ADs used for domestic wastewater treatment in Zambia. Primary data on the technical performance of 15 ADs were collected over a 6-month period and in-person interviews were conducted with heads of 120 households. Findings from this study suggest that ADs offer comparable wastewater treatment efficiencies and greater GHG emission reduction benefits relative to conventional septic tanks (STs), with the greatest benefits in settings with reliable access to water, use of low efficiency solid fuels and with sufficient demand for biogas in proximity to supply. However, absent a mechanism to monetize additional benefits from biogas recovery, ADs in this context will not be a financially attractive investment relative to STs. Our financial analysis suggests that, under the conditions in this study, a carbon price of US$9 to $28 per tCO2e is necessary for positive investment in ADs relative to STs. Findings from this study contribute empirical evidence on ADs as a sanitation and clean energy strategy, identify conditions under which the greatest benefits are likely to accrue and inform international climate efforts on the carbon price required to attract investment in emissions reduction projects such as ADs.

Modeling California policy impacts on greenhouse gas emissions

This paper examines policy and technology scenarios in California, emphasizing greenhouse gas (GHG) emissions in 2020 and 2030. Using CALGAPS, a new, validated model simulating GHG and criteria pollutant emissions in California from 2010 to 2050, four scenarios were developed: Committed Policies (S1), Uncommitted Policies (S2), Potential Policy and Technology Futures (S3), and Counterfactual (S0), which omits all GHG policies. Forty-nine individual policies were represented. For S1–S3, GHG emissions fall below the AB 32 policy 2020 target [427 million metric tons CO2 equivalent (MtCO2e)yr−1], indicating that committed policies may be sufficient to meet mandated reductions. In 2030, emissions span 211–428MtCO2eyr−1, suggesting that policy choices made today can strongly affect outcomes over the next two decades. Long-term (2050) emissions were all well above the target set by Executive Order S-3-05 (85MtCO2eyr−1); additional policies or technology development (beyond the study scope) are likely needed to achieve this objective. Cumulative emissions suggest a different outcome, however: due to early emissions reductions, S3 achieves lower cumulative emissions in 2050 than a pathway that linearly reduces emissions between 2020 and 2050 policy targets. Sensitivity analysis provided quantification of individual policy GHG emissions reduction benefits.

Energy and GHG emission reduction potential of power generation from sugarcane residues in Thailand

Electric power production using biomass residues from agricultural production using high efficiency electricity generation technologies would reduce greenhouse gas (GHG) emissions and contribute to climate change mitigation. This study investigated the case of the sugar industry in Thailand and identified scenarios offering GHG emissions reduction benefits. Electricity generation potential from using sugarcane residues and/or upgrading power generation systems represent beneficial options. The largest potential of electricity export to the national grid can be achieved by upgrading boiler systems of all sugar mills to 103bar and 515°C. Using 19% of the generated sugarcane tops and leaves along with bagasse can generate 9TWh electricity and would reduce GHG emissions by 4.8Mt CO2 equivalent a year. The economic analysis shows that using high steam pressure boiler configurations for power generation results in substantial reduction in production cost and increase in benefit.

Energy and GHG Analysis of Rural Household Biogas Systems in China

The Chinese government has taken great efforts to popularize rural household scale biogas digesters, since they are regarded as an effective approach to address energy shortage issues in rural areas and as a potential way of reducing greenhouse gas (GHG) emissions. Focusing on a typical rural household biogas system, the aim of this study is to systematically quantify its total direct and indirect energy, concentrating on non-renewable energy and the associated GHG emission cost over the entire life cycle to understand its net dynamic benefits. The results show that the total energetic cost for biogas output is 2.19 J/J, of which 0.56 J is from non-renewable energy sources and the GHG emission cost is 4.54 × 10−5 g CO2-equivalent (CO2-eq), with respect to its design life cycle of 20 years. Correspondingly, a net non-renewable energy saving of 9.89 × 1010 J and GHG emission reduction of 50.45 t CO2-eq can be obtained considering the coal substitution and manure disposal. However, it must be run for at least 10 and 3 years, to obtain positive net non-renewable energy savings and GHG emission reduction benefits, respectively. These results have policy implications for development orientation, follow-up services, program management and even national financial subsidy methods.

해양바이오에너지 개발사업의 온실가스 저감편익 추정

환경문제가 심각해지고, 에너지안보에 대한 관심이 높아지면서 화석연료를 대체할 신재생에너지개발은 더욱 절실해지고 있다. 정부는 2030년까지 바이오에너지부분의 50%를 해양바이오에너지에서 생산한다는 계획을 발표하였다. 본 연구는 해양바이오에너지 개발사업으로 인하여 저감되는 온실가스의 저감편익을 조건부가치측정법을 이용하여 추정하고자 한다. 단일경계 양분선택형 모형에 스파이크 모형을 적용하였으며, 그 결과 해양바이오에너지 개발사업의 온실가스 저감편익은 단일경계 양분선택형에서는 가구당 평균 지불의사액이 4,190원으로 추정되었다. 이를 설문을 진행한 지역으로 확장하면 연간 501억원에 달한다. 이와 같은 연구결과는 해양바이오에너지 개발사업의 시행여부를 결정하는 비용편익분석이나 해양바이오에너지 개발사업정책에 있어서 편익의 유용한 정보로 활용할 수 있다.

Potential energy and greenhouse gas emission effects of hydrogen production from coke oven gas in U.S. steel mills

For this study, we examined the energy and emission effects of hydrogen production from coke oven gas (COG) on a well-to-wheels basis and compared these effects with those of other hydrogen production options, as well as with those of conventional gasoline and diesel options. We then estimated the magnitude of hydrogen production from COG in the United States and the number of hydrogen fuel cell vehicles (FCVs) that could potentially be fueled with the hydrogen produced from COG. Our analysis shows that this production pathway can achieve energy and greenhouse gas emission reduction benefits. This pathway is especially worth considering because first, the sources of COG are concentrated in the upper Midwest and in the Northeast United States, which would facilitate relatively cost-effective collection, transportation, and distribution of the produced hydrogen to refueling stations in these regions. Second, the amount of hydrogen that could be produced may fuel about 1.7 million cars, thus providing a vital near-term hydrogen production option for FCV applications.

Fuel-Cycle Greenhouse Gas Emissions Impacts of Alternative Transportation Fuels and Advanced Vehicle Technologies

The greenhouse gas (GHG) emissions reduction potentials of various near- and long-term transportation technologies were estimated. The estimated per-travel-distance GHG emissions results indicate that alternative transportation fuels and advanced vehicle technologies can help to significantly reduce transportation-related GHG emissions. Of the near-term technologies evaluated, electric vehicles, hybrid electric vehicles, compression-ignition, direct-injection vehicles, and E85 (85 percent ethanol and 15 percent gasoline) flexible-fuel vehicles can reduce fuelcycle GHG emissions by more than 25 percent on a fuel-cycle basis. Electric vehicles powered by electricity generated primarily from nuclear and renewable sources can reduce GHG emissions by 80 percent. Other alternative fuels (such as compressed natural gas and liquefied petroleum gas) offer limited, but positive, GHG emissions reduction benefits. Among the long-term technologies evaluated, conventional sparkignition and compression-ignition engines powered by alternative fuels and gasoline- and diesel-powered advanced vehicles can reduce GHG emissions by 10 to 30 percent. Dedicated ethanol vehicles, electric vehicles, hybrid electric vehicles, and fuel-cell vehicles can reduce GHG emissions by more than 40 percent. Spark-ignition engines and fuel-cell vehicles powered by cellulosic ethanol and solar hydrogen (for fuel-cell vehicles only) can reduce GHG emissions by over 80 percent. In conclusion, both near- and long-term alternative fuels and advanced transportation technologies can play a role in reducing GHG emissions from the transportation sector.