Dioxide Abatement Research Articles

Board Interlock Networks and Corporate Low-Carbon Innovation in China: Does Position Matter?

Through combining the resource dependence theory and social network theory, this study sheds light on how two major kinds of interlocking network positions—central network position and structural holes position—drive corporate low-carbon innovation. We consider the mediating effect of information asymmetry and knowledge absorptive capacity to reap benefits from occupying the two advantageous network positions. We have empirically investigated a sample of 3365 listed firms over the period of 2009–2018 drawn from China, the largest emerging market economy as well as the biggest carbon dioxide emitter. Our main results show that either holding a central network position or spanning a structural holes position plays a significant role in stimulating low-carbon technologies, and the promotion effect can be partially channeled through downward information asymmetry and upward knowledge absorptive capacity. Our findings differ from earlier work because of our emphasis on network position, and our specific focus on corporate low-carbon innovation and China's unique setting, rather than network size, greenhouse gas emissions, and developed economies. This study also provides significant implications for executives striving to improve firms’ low-carbon innovation performance, and for policymakers seeking ways to fulfill the mission of carbon dioxide abatement.

Renewable origin, additionality, temporal and geographical correlation – eFuels production in Germany under the RED II regime

E-fuels are a promising technological option to reduce the carbon footprint in the transportation sector. To ensure the renewable origin of electricity-based fuels and minimize the impact of power-to-liquid facilities on the electricity grid, the European Union implemented electricity purchase conditions within the Renewable Energy Directive II. In this work, we analyze the impact of these electricity purchase conditions on the optimal placement, dimensioning and operation of facilities and the German electricity system. The results show that implementing the proposed electricity purchase conditions increases electrolysis capacity by 15.8% and reduces utilization by 672 h in 2030. With the constrained electricity supply, the power-to-liquid facilities concentrate on network nodes with high renewable potential, while the carbon dioxide supply loses importance. Overall, the German electricity system is not heavily affected by the proposed purchase conditions as the required renewable generation capacities only increase slightly. At the same time, carbon dioxide abatement costs rise by 14.3% by introducing the electricity purchase conditions.

Comprehensive analysis on the effect of lube oil on particle emissions through gas exhaust measurement and chemical characterization of condensed exhaust from a DI SI engine fueled with hydrogen. Part 2: Effect of operating conditions

The need to cope with carbon dioxide abatement has prompted the development of innovative technologies for sustainable mobility. Meanwhile, these technologies consolidate, an important role will be played by internal combustion engines fed with non-fossil fuels such as hydrogen. Theoretically, the combustion of hydrogen should not produce carbon-based emissions. Nevertheless, particles can be found in the exhaust of hydrogen-fueled engines because of the lubricating oil. In this study, a thorough examination of the impact of the engine lubricant on the mechanisms leading to the formation of the particles and the high levels of hazardous pollutants was performed in this study. Experiments were carried out on a direct injection spark ignition engine fueled with hydrogen. The analysis was conducted at 2000 and 3000 rpm both low and full load. Number and size particle distribution were determined by means of on-line measurement on the diluted exhaust. Off-line chemical characterization through analytic techniques was realized on the condensed exhaust and on the particles collected on a filter. Experimental results pointed out that the extent of the particle size varies according to the engine speed and load, evidencing the different role of the oil ascribable to the environmental conditions. It was found that aromatic molecules and nanoparticles are present in the exhausts at all the investigated operating conditions, whereas soot aggregates are formed only at high engine speed.

A comprehensive review of enhanced in-situ CO2 mineralisation in Australia and New Zealand

The urgent need to accelerate permanent anthropogenic carbon dioxide (CO2) abatement has led to a growing interest in in-situ CO2 mineralisation globally. This review outlines the progress of in-situ CO2 mineralisation in Australia and New Zealand, while focusing on potential sink reservoirs for mineralisation, including magnesium-rich and calcium-rich ultramafic and mafic rocks. These rock types are abundant in various regions across both countries. The review first begins by highlighting the current status and progress of Australian and New Zealand emissions and national abatement goals. It then previews the currently funded carbon capture, utilisation, and storage (CCUS) projects across both countries and discusses where in-situ CO2 mineralisation stands to complement other CO2 storage methods. Secondly, it details the different mineralisation mechanisms within selected rock types/complexes in Australia and New Zealand, followed by a discussion of the limitations and advantages of each selected major rock type/complex within both countries, including the relative distances between deposits and major emission hotspots. Finally, within this review we examine the governmental funding and perception of enhanced in-situ CO2 mineralisation within the two countries. An example in Mount Keith Ultramafic Complex (MKUC) is also presented, which shows the relationship between rock permeability, expected CO2 injection, and the estimated cost per ton for direct pumping into low permeability Peridotite deposits. The results show an inversely proportional relationship between permeability and injection rate, and thus the cost per ton of CO2 stored.The estimated cost calculations clearly demonstrate that the limiting factor of in-situ mineralisation is not the availability of sink reservoirs within Australia and New Zealand but rather the need for significant government incentives to present an attractive breakeven cost that can compete in the CO2 storage market. The results also show that New Zealand currently has a slight advantage due to the 2-fold higher carbon pricing compared to Australia.

Electricity Production and Sustainable Development: The Role of Renewable Energy Sources and Specific Socioeconomic Factors

An eco-friendly and sustainable power production system constitutes the cornerstone of every country’s strategic plan to tackle climate change and enhance energy resource autonomy. Carbon dioxide abatement in electricity generation, in addition to being a necessary condition for t “green” energy transition, can contribute greatly to cleaner industrial production and sustainable development. Emphasizing this key role of the power sector, the present research focuses on shedding light on the impact of renewable energy resources (RES), per capita gross domestic product (GDP), electricity gross fixed capital formation (GFCF) and urbanization in the CO2 intensity, and the sustainability level of electricity production. The analysis is based on a comprehensive dataset of 31 countries including 26 European countries, U.S.A., Japan, Australia, Canada, and New Zealand from 1995 until 2018. The econometric outcomes revealed the strong statistical significance of all variables and a plethora of causality relationships, upon which several policy suggestions are made. Interestingly, GDP per capita beyond a certain level can gradually become an aggravating factor for the electricity carbon footprint. Similarly, the vital role of RES in clean electricity production was confirmed as expected, yet surprisingly, this effect also appears to reverse after a certain percentage of total RES reliance. In contrast to urbanization, the electricity GFCF parameter is estimated to have an adverse effect on electricity CO2 intensity, indicating that the vast amount of new investments in the power sector concerns carbon-intensive technologies. Finally, a dynamic analysis is carried out, revealing to policy makers the necessary time frame after which the implementation of new energy policies can have the full impact on the carbon emissions of electricity generation.

Toward Low-Carbon-Footprint Glycolic Acid Production for Bioplastics through Metabolic Engineering in Escherichia coli

Researchers are focusing on biological carbon dioxide abatement against the currently employed physical and chemical methods. Sustainable approaches for carbon conversion into indispensable bulk chemicals are the need of the hour. In this study, glycolic acid (GA), one of the promising components for bioplastics, food, and pharmaceutical industries, was produced in a low-carbon footprint manner using genetically engineeredEscherichia coli for the first time. By fine-tuning the genes in the TCA cycle and glyoxylate shunt, GA yield reached 0.21 g/g-glucose with a productivity of 0.08 g/L/h. Regeneration of NADPH was improved using glyceraldehyde-3-phosphate dehydrogenase (gapC) fromClostridium acetobutylicum in the glucose-6-phosphate-1-dehydrogenase (zwf) mutant. To further enhance CO2 uptake and carbon flux into the TCA cycle, phosphoenolpyruvate carboxylase (ppc) and pyruvate carboxylase (pyc) were applied. As a result, the titer and productivity of GA reached 11.9 g/L and 0.23 g/L/h, respectively, with a 41% reduction in CO2 emission compared to the strain without ppc expression during fermentation. Finally, GA was polymerized to form poly(glycolic acid) and characterized by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The presented strategy serves as an eco-friendly and cost-efficient approach for chemical production toward low-carbon emission.

Bottom-up analysis of energy conservation and carbon dioxide mitigation potentials by extended marginal abatement cost curves for pulp and paper industry

The energy-intensive pulp and paper industry is a major contributor to carbon dioxide emissions. The potential to reduce energy consumption and carbon dioxide emissions is generally assessed using energy conservation supply curves and marginal abatement cost curves; however, both of these methods have inherent faults. For a given negative cost, conventional marginal abatement cost curves tend to favor options that lead to small reductions in carbon dioxide emissions over options that produce larger reductions. In the current study, we employed extended versions of energy conservation supply curves and marginal abatement cost curves to analyze the various options to reduce energy consumption and carbon dioxide emissions. The technical potential energy savings and carbon dioxide abatement were respectively estimated at 5.05% of the final energy use in the sector and 6.32% of carbon dioxide emissions in 2019. We determined that 52.3% of the electricity savings and 82.8% of fuel savings could be achieved in a cost-effective manner. Additionally, the utilization of solid recovered fuels remains a largely untapped opportunity to reduce carbon dioxide emissions for the Taiwanese pulp and paper industry. Thus, efforts should be made to establish a comprehensive database pertaining to the direction and volume of waste flows and improve waste collection networks with corresponding standards pertaining to solid recovered fuels quality and air pollution.

Experimental Investigation and Modeling of the Sulfur Dioxide Abatement of Photocatalytic Mortar Containing Construction Wastes Pre-Treated by Nano TiO2

A photocatalytic mortar containing recycled clay brick powder (RCBP), recycled fine aggregate (RFA), recycled glass (RG), and nanoscale titanium dioxide (NT) was fabricated to degrade low-concentration sulfur dioxide. Instead of intermixing or dip-coating, NT was firstly loaded onto the surface of carriers (RFA and RG) using a soaking method to prepare composite photocatalysts (CPs) denoted as NT@RFA and NT@RG. The prepared CPs can both take full advantage of the intrinsic characteristics of construction wastes, namely, the high porosity and alkalinity of RFA and the light-transmitting property of RG, and can significantly reduce the cost of using NT. RG in high dosage potentially triggers alkali–silica reaction (ASR) in cement-based materials, which affects the durability of the prepared mortar. RCBP, another typical construction waste sourced from crushed clay bricks, was proven to be a pozzolan similar to grade II fly ash. The combined use of RCBP and RG in photocatalytic mortar is expected to simultaneously improve durable performance and further raise the upper content limit of construction wastes. Results exhibit that 70% cement plus 30% RCBP as cementitious material can sufficiently control ASR to an acceptable level. The filling effect and the pozzolanic reaction caused by RCBP result in a decline in porosity and lessened alkalinity, which decreases sulfur dioxide removal. The paper uses both response surface methodology (RSM) and an artificial neural network (ANN) to model photocatalytic efficiency with various initial concentrations and flow rates and finds the ANN to have a better fitting and prediction performance.

Plastics industry works to comply with China[StQuote]s [LDQUO]dual carbon[RDQUO] targets

As an increasingly accepted way of relieving global warming, collaborative carbon dioxide (CO2) abatement could improve not only emission performance, but also cost-effectiveness of abatement. In this study, we analyze the cost savings and benefits of collaborative abatement in the context of China by using data envelopment analysis (DEA) approach. Specifically, we establish 63 collaborative abatement scenarios by dividing the Mainland China into six main regions, and then estimate the costs savings in each collaboration abatement scenario. Through investigating the gains for each region in various scenarios, the best collaborative partners for each region are suggested from perspectives of benefit maximization. Furthermore, the contribution of each region to collaborative abatement cost saving is also differentiated with the Shapley value approach.

Carbon dioxide abatement by integration of methane bi-reforming process with ammonia and urea synthesis

The use of thermal power plants has been increasing lately, despite its use being associated with high greenhouse gases emissions, especially carbon dioxide. In the context of the Paris Agreement of 2015, carbon dioxide capture, storage and utilization techniques must be increasingly employed to reduce environmental impacts. The utilization of carbon dioxide from a power plant flue gas as feedstock to other chemicals synthesis (such as ammonia and urea) arises as a good alternative to achieve near-zero carbon dioxide emissions. The aim of this work is to propose an alternative route, based on the bi-reforming of methane, for the synthesis gas section of ammonia and urea production plants, in order to promote carbon dioxide abatement, comparing this innovative route with the conventional and century-long existing process. Technical and environmental metrics of the proposed and conventional routes were compared. Aspen Plus® process simulator was used to simulate the bi-reforming process and both routes for ammonia and urea synthesis and choose the operational parameters. Simulation results show that for a target production of 2000 tonne/day of urea, the proposed alternative route has the potential to abate 745 tonne/day of carbon dioxide, while the conventional route emits 1156 tonne/day of carbon dioxide. Comparison of technical metrics of both routes shows that the proposed route requires an electricity usage of 0.27 MWh/tonne of products while the conventional route requires 0.47 MWh/tonne of products. However, hydrogen yield in the conventional route is higher than in its counterpart, with 0.41 and 0.22 tonnes of hydrogen produced for each tonne of inlet natural gas in the conventional and proposed routes, respectively. Comparison of economic metrics of both configurations show that none of the routes are economically viable, however, the alternative route has better economic indicators besides successfully promotes carbon dioxide abatement.

Estimation of Above-Ground Carbon-Stocks for Urban Greeneries in Arid Areas: Case Study for Doha and FIFA World Cup Qatar 2022

Urban areas are significant sources of anthropogenic carbon dioxide (CO2), which elevates air pollution. However, urban greenery has a positive effect on mitigating air pollution and the impact of CO2on the climate. Quantifying the benefits of greenery for urban environments involves complex calculations and requires significant resources. Such a quantifying exercise is not cost-effective. The satellite remote sensing method can analyze current and near-present carbon-stock dynamics through spectral band imaging. In this research study, field measurements determine above-ground carbon (AGC) stock. The field measurements are derived from three types of land use, comprising public parks and gardens, institutional parks, and street and avenue greenery in selected locations in Doha city in Qatar. These field measurements are then correlated with results from satellite images. Linear and non-linear regression models are established between AGC and five vegetative spectral indices (VIs) derived from the Landsat 8 Operational Land Imager (OLI). The AGC stock for the selected locations in Doha in 2014 is evaluated using the highest coefficient of determination with the highest accuracy expected. The results of the analysis reveal that both the normalized difference vegetation index (NDVI) (R2= 0.64) and the relative ratio vegetation index (R2= 0.71) significantly correlate with the AGC in public parks. In avenue vegetation, all the VIs exhibit high R2, but the best fit is NDVI (R2= 0.87). The CO2equivalent range evaluated from the AGC in the plots studied in Doha is measured as 650.6 tons for the period between 2014 and 2020, with an annual sequestration rate of 108.4 tons per year. This CO2equivalent storage amount has the social value of USD 42,286, which is the equivalent of QR 155,192. The AGC-VI correlation in land-use groups may be influenced by the turf grass and impervious surfaces in the background of the images. Further study of urban landscapes and vegetation with high biomass is likely to show its positive effects for cities and that it can improve carbon dioxide abatement, resulting in more sustainable societies. This improvement in CO2abatement in Qatar can be useful for various environmental estimations for the upcoming mega event of World Cup 2022.

Upgrading exergy utilization and sustainability via supersonic separators: Offshore processing of carbonated natural gas

Offshore processing of natural gas with 44%mol carbon dioxide at remote deep-water oil-and-gas fields is invariably characterized by low-efficiency power generation via gas-fired turbines releasing hot flue-gas and entailing high degradation of resources, high carbon emissions and low sustainability. This work demonstrates how to upgrade exergy utilization and consequently process sustainability by using supersonic separators in some gas processing steps; namely: (i) water dew-point adjustment; (ii) hydrocarbon dew-point adjustment; and (iii) carbon dioxide abatement to 20%mol. To accomplish this, the exergy performance of two supersonic separator gas processing alternatives are compared with conventional gas processing comprising triethylene-glycol absorption for water dew-point adjustment, Joule-Thomson expansion hydrocarbon dew-point adjustment and membrane-permeation carbon dioxide removal. Since exergy is measured relatively to a reference environmental reservoir, two such reference reservoirs are used: RER-1: standard atmosphere with 2%mol water containing hydrocarbons at combustion chemical equilibrium with air species; and RER-2: 1atm water-saturated raw natural gas in equilibrium with liquid water. Aspen-HYSYS simulations are used to solve mass/energy balances and thermodynamic property calculations. With RER-2 the conventional gas processing conserves 63.3% of the inlet exergy, while the two alternative supersonic separator processes attain 66.5% and 72.4% of exergy conservation, proving the associate gains of exergy efficiency and sustainability.

Spray drying absorption for desulphurization: a review of recent developments

Sulphur dioxide (SO2) abatement technologies, i.e. flue gas desulphurization (FGD), have proven effective in curtailing the harmful SO2 emissions resulting from coal combustion for electrical power generation. New regulations on these emissions now require some power utilities to retrofit new FGD units to existing coal-fired power plants to meet required emission standards. Wet FGD limestone scrubbing has been predominantly used over other competing technologies. However, the simplicity of the spray-drying absorption (SDA) technology has made it an attractive alternative to the wet scrubbing process. SDA offers huge savings on energy, water, operating cost and maintenance. Despite high cost of the sorbent (hydrated lime) used, recent advances in SDA process offer considerable economic and technical advantages ranging from improved sorbent utilization, better atomization and enhanced performance. Alternative sorbents and additives are continuously being explored for simultaneous removal of pollutant gases from flue gas. The performance improvement areas in a lime spray drying system include the use of inorganic salt additives, recycling of the dried product and the use of siliceous materials. This study is intended to review FGD systems applicable to coal-fired power plants, through a technical comparison between competing technologies. Additionally, a review of the spray-drying absorption process and operating parameters affecting their efficiency was carried out, together with a critical assessment of the literature published to date.

Life cycle water consumption for oxyfuel combustion power generation with carbon capture and storage

To fulfill its commitment to carbon emission reduction and peak carbon emission in 2030, China is expected to conduct large-scale carbon capture and storage deployment in future decades, considering the dominant role of coal-based energy for power generation. As an important carbon emission mitigation technology, oxy-fuel combustion will play a significant role in this process. Meanwhile, the water scarcity in China is also worthy of attention, especially in coal-rich areas which are usually water-scarce. The development and implementation of coal-based carbon capture and storage technology may exacerbate the water shortage situation in these regions. Considering this background, a correct analysis of the water use of oxy-fuel combustion power plants is of great importance, before implementing the large-scale deployment of carbon capture and storage. Therefore, this study aims to assess the life-cycle water consumption of a 600 MW oxy-fuel combustion power plant, retrofitted from a typical 600 MW coal-fired power plant in China. Based on a tiered hybrid method, the direct and indirect water consumption of a typical oxy-combustion CCS project is evaluated. Results show that 4.63 L of water is used for capturing 1 kg of carbon dioxide, while the calculated water intensity for power generation is 3.79 L/kWh. The operation and maintenance processes dominate the total water consumption, in which the cooling mode exerts a great influence on life cycle water consumption. Once-through cooling has lower water consumption than recirculating cooling in the retrofitted oxy-combustion power plant. If we compare water consumption with other power generation technologies, the water intensity of oxy-combustion carbon capture and storage power production is lower than that of bio-power, but beyond that of solar photovoltaic and wind power. Moreover, based on the thermal power production in China in 2017 and the water use calculated in this study, transforming all the thermal power plants to oxy-combustion systems is hardly feasible as the induced water withdrawal will account for 17.26%–827.19% of the total industrial water budget in 2030. Further regional analysis indicates that even to achieve 10 Gt of carbon dioxide abatement, Shanxi province will encounter great difficulties due to reduced water availability.

Microalgae Biomass Production for Biofuels in Brazilian Scenario: A Critical Review

The Brazilian environmental, economic, and social conditions for the long-term establishment of mass culture of microalgae for either biofuel production or greenhouse gases (GHG) abatement are described in detail. A brief historical introduction of the microalgal biotechnology is presented followed by a compilation of Brazilian published research works on microalgae, with special emphasis on microalgal Brazilian biodiversity and applied phycology. Several case studies on Brazilian microalgal biorefineries are presented with special emphasis on wastewater (WW) treatment. The manuscript also adds valuable new information about which regions of the country offer better growing conditions for dozens of endemic species. Favorable climatic and environmental conditions for the cultivation of several microalgae (green) and cyanobacteria species in specific regions of the country are suggested. Finally, based on realistic biomass productivities and product yields for the Brazilian context, several scenarios for biofuel production and/or carbon dioxide (CO2) abatement have been designed, and results are presented and critically discussed. Brazilian self-sufficiency on either fuels for transportation or GHG abatement using exclusively microalgae is quite challenging but achievable accordingly with the present state of the art.

Analysis of energy efficiency improvement and carbon dioxide abatement potentials for Swiss Food and Beverage sector

The food and beverage (F&B) production is the second most energy consuming industry sector, consuming up to 14% (22 PJ) of the Swiss industry's total final energy (TFE) and emitting 14% (0.6 million tonnes) of the industry's total CO2. In the period from 2004 to 2017, the sector's energy consumption has been increasing at a faster rate than production, which implies deterioration of energy efficiency (EE). Against the background of implicit EE improvement target of 26% between 2017 and 2050 under the assumption of constant future production, this study investigates the options of realizing the target. The process-related (e.g. excluding building envelope) technical EE improvement potential of the Swiss F&B sector is estimated at 25% whereas the currently commercially available energy-efficient technologies can potentially reduce 18% of the sector's current TFE. The cost-effective potential estimated by means of a bottom-up approach (cost curves) ranges from 14% to 16% for energy efficiency and 18% to 21% for CO2. Results of sensitivity analysis indicate that low energy prices may act as a barrier for the adoption of cross-cutting technologies. A qualitative analysis of emerging technologies presented along with the detailed cost-effectiveness analysis of commercially available energy-efficient technologies can help to overcome the techno-economic barriers and achieve the implicit EE improvement target of the Swiss F&B sector.

The rapid development of the photovoltaic industry in China and related carbon dioxide abatement costs

There is a consensus within the international community that replacing traditional fossil energy with renewable energy, such as photovoltaic energy, will help mitigate climate change. However, the literature addressing the rapid development issues of the photovoltaic industry and related carbon dioxide abatement costs is limited. China is currently the largest photovoltaic producer and consumer in the world, hence suitable as our research object. In this paper, a fixed effect panel model with provincial panel data during the period 2012–2016 is applied to study the factors that influence China’s photovoltaic industry. The empirical results indicate that carbon dioxide emission mitigation requirements, government subsidies, technological progress, energy substitution, economic growth, and illumination resources promote the development of the photovoltaic industry. We further adapt the cost estimation model to estimate the average carbon dioxide abatement cost of photovoltaic electric power in China at 679.72 yuan/ton in 2015 and 681.88 yuan/ton in 2016. Compared with wind power and biomass energy, photovoltaic electric power is currently less economical for carbon dioxide emission reduction. Moreover, the future carbon dioxide abatement cost is predicted using a scenario analysis at 118.94–259.42 yuan/ton in 2025 and 42.63–171.95 yuan/ton in 2030. Since the carbon dioxide abatement cost in 2030 is in line with the future price level of the carbon trading market, it will be both economical and feasible to use photovoltaic electric power to decrease carbon dioxide emissions in the future.

Does environment-biased technological progress reduce CO2 emissions in APEC economies? Evidence from fossil and clean energy consumption.

Environment-biased technological progress plays a critical role in carbon reduction, while the association among environment-biased technological progress, energy consumption, and carbon emissions has not been paid enough attention. Working with a unique spatial panel dataset of APEC economies spanning the 2000-2017 period, we employed the nonspatial panel model and the spatial panel model to investigate the role of fossil energy (FE) and clean energy (CE) consumption in carbon dioxide (CO2) abatement through environment-biased technological progress (EBTP). We decomposed EBTP into both emission-reducing biased technological progress (ErBTP) and energy-saving biased technological progress (EsBTP). The results show that the direct effect of EBTP on CO2 emissions was significantly negative and that the direct effect of ErBTP was significantly larger than that of EsBTP. EBTP reduced CO2 emissions through CE consumption, whereas it increased CO2 emissions through FE consumption, that is, EBTP had a "backfire effect" on FE consumption. More into detail, ErBTP had a larger effect on CO2 emissions in developing economies, while EsBTP played a more important role in developed economies. Furthermore, the results of the robustness test were consistent with our findings. Finally, several policy options were suggested to reduce CO2 emissions in APEC economies.

Analysis of the integration of the three-way catalyst thermal management in the on-line supervisory control strategy of a gasoline full hybrid vehicle

Full hybrid electric vehicles have proven to be a midterm viable solution to fulfil stricter regulations, such as those regarding carbon dioxide abatement. Although fuel economy directly benefits from hybridization, the use of the electric machine for propulsion may hinder an appropriate warming of the aftertreatment system, whose temperature is directly related to the emissions conversion efficiency. The present work evaluates the efficacy of a supervisory energy management strategy based on Equivalent Minimization Consumption Strategy (ECMS) which incorporates a temperature-based control for the thermal management of the Three-Way Catalyst (TWC). The impact of using only the midspan temperature of TWC is compared against the case where temperature at three different sampling points along the TWC length are used. Moreover, a penalty term based on TWC temperature has been introduced in the cost functional of the ECMS to allow the control of the TWC temperature operating window. In fact, beyond a certain threshold, the increase of the engine load, requested to speed up TWC warming, does not translate into a better catalyst efficiency, because the TWC gets close to its highest conversion rate. A gasoline P2 parallel full hybrid powertrain has been considered as test case. Results show that the effects of the different calibrations strategies are negligible on the TWC thermal management, as they do not provide any improvements in the fuel economy nor in the emissions abatement of the hybrid powertrain. This effect can be explained by the fact that the charge sustaining condition has a greater weight on the energy management strategy than the effects deriving from the addition of the soft constraints to control the TWC thermal management. These results hence encourage the use of simple setups to deal with the control of the TWC in supervisory control strategies for full hybrid electric vehicles.

Timelines for mitigating the methane impacts of using natural gas for carbon dioxide abatement

Reducing carbon dioxide (CO2) emissions through a reliance on natural gas can create a hidden commitment to methane (CH4) leakage mitigation. While the quantity of CH4 leakage from natural gas has been studied extensively, the magnitude and timing of the CH4 mitigation required to meet climate policy goals is less well understood. Here we address this topic by examining the case of US electricity under a range of baseline natural gas leakage rate estimates and emissions equivalency metrics for converting CH4 to CO2-equivalent emissions. We find that CH4 emissions from the power sector would need to be reduced by 30%–90% from today’s levels by 2030 in order to meet a CO2-equivalent climate policy target while continuing to rely on natural gas. These CH4 emissions reductions are greater than the required CO2 reductions under the same policy. Alternatively, expanding carbon-free sources more rapidly could meet the 2030 target without reductions in natural gas leakage rates. The results provide insight on an important policy choice in regions and sectors using natural gas, between emphasizing a natural gas supply chain clean-up effort or an accelerated transition toward carbon-free energy sources.