Energy Efficiency CO2 Research Articles

Investigation of carbon dioxide absorption performance in amine amino acid salts for upgrading biogas applications: Blended absorbents of piperazine and amino acid solutions

BackgroundThe increasing amount of CO2 in the atmosphere is a critical environmental issue, necessitating the development of efficient CO2 capture technologies. Amine amino acid solutions (AAAS) have demonstrated potential in improving CO2 absorption and desorption. This study explores the efficiency of various AAAS, including piperazine (PZ), glycine (Gly), lysine (Lys), sarcosine (Sar), and alanine (Ala), under specific experimental conditions. MethodologyThe CO2 absorption and desorption processes were investigated using AAAS under conditions of 45 % CO2 at 313.15 K and with pure N2 at 353.15 K, respectively. The findings obtained for CO2 loading, regeneration rate, CO2 desorption heat, and 13C nuclear magnetic resonance (NMR) are valuable for understanding their impacts on the design and improvement of energy efficiency CO2 capture techniques. Furthermore, the physicochemical properties of PZ + lysine solutions such as density, viscosity, and vapor pressure were also measured at equimolar concentration ranges such as 0.75 M, 1.0 M, 1.25 M, and 1.5 M at T = 303.15 K to 353.15 K and 0.1 MPa pressure. Significant findingsThe study revealed significant enhancements in CO2 absorption and desorption with the addition of AAAS compared to monoethanolamine (MEA) solutions. Notably, among all the solutions, the PZ + lysine solution exhibited the maximum CO2 cyclic capacity at 0.792 mol CO2/mol absorbent, and the lowest regeneration heat. These findings provide valuable insights into the design and improvement of energy-efficient CO2 capture techniques.

Strategizing CO2 emission commitments in mainland China by integrating the experiences of primary energy consumption structures from the European assemblage and the USA in 1971–2021

To fulfill CO2 emission commitments becomes strategic to meet energy demands of sustainable economic growth via adjusting primary energy consumption structure. This study analyzed energy efficiency and CO2 emission intensity in the top three world economies in the period 1971–2021 and attempted to optimize structure of primary energy consumption for the CO2 emission commitments in mainland China, reaching peak emission by 2030 and neutrality by 2060. Results indicated that the USA and the European 16 – countries had significant higher energy efficiency and lower CO2 emission intensity than mainland China (α = 0.05). Reducing coal consumption is an efficient measure to reduce CO2 emission from fossil energy in the structure. However, renewable energies are crucial for achieving CO2 emission neutrality. As predicted, mainland China might peak CO2 emission by 2030 at 14.7 × 109 ton CO2 with 278 × 1018 J of total primary energy consumption, and would neutralize CO2 emissions by 2060 from 184 × 1018 J of primary fossil energy in the consumption structure in 2030 with renewable energies, hydropower, and nuclear as planned. Findings of this study provide a practical strategy for fulfilling CO2 emission commitments in mainland China and might be applicable to the developing world.

Life cycle assessment of synthetic natural gas production from captured cement’s CO2 and green H2

Research on the environmental benefits of carbon capture and utilization (CCU) in cement production so far, has predominantly emphasized energy efficiency enhancements and CO2 emission reductions at a CCU product level, neglecting broader environmental consequences for the sector. This research broadens this perspective by providing an extensive life cycle assessment (LCA) of a circular Portland cement (CPC) model. Synthesized methane is used as input fuel through green hydrogen and calcium-looping (CaL) post-combustion captured CO2 from cement flue gas. Comparative analysis with ordinary Portland cement (OPC) reveals significant reductions in climate change and fossil resource use environmental impact categories. However, trade-offs are evident in acidification, water use, and minerals and metals resource consumption. The electrolysis system is a critical contributor due to the high electricity demand for hydrogen production, and its environmental impact depends largely on the renewable electricity source. The wind-based electrolysis model yields the most favourable results, followed by mixed (50% solar – 50% wind) and solar scenarios. These findings offer valuable insights for the cement industry, supporting stakeholders decision making on the adoption of sustainable circular production methods.

High Performance Protonic Ceramic Electrochemical Cells Operating at

Protonic ceramic electrochemical cells (PCECs) can operate in both fuel cell and steam electrolysis modes for efficient power generation and green hydrogen production. Thanks to the low activation energy of proton conduction, PCECs are uniquely capable of operating at temperatures below 600°C. Although some intriguing demonstrations of intermediate-temperature (500-600°C) PCECs (IT-PCECs) have been made in the last decade, the operating temperature of PCECs is still too high to revolutionize ceramic electrochemical cell technology, which is ascribed to the high ohmic resistance and positive electrode polarization resistance. It has been also recognized the electrode polarization resistance dominates the total resistance at <500°C. These challenges suggest both the electrolyte and positive electrode should be redesigned to lower the PCEC operating temperature.In this work, we present two main approaches to reducing electrolyte ohmic resistance, electrolyte-positive electrode contact resistance, and electrode polarization resistance, which enables PCECs operation at <500°C. First, by using the ultrasonic spray coating system to coat the electrolyte layer on a negative electrode substrate with low Ba-deficiency, a bamboo-structured, ultrathin, and chemically homogeneous electrolyte can be fabricated. Second, a newly in-situ formed composite positive electrode was developed, which enhances the interfacial bonding between the positive electrode and electrolyte, further reducing ASRo , while improving both bulk oxygen-ion diffusion coefficient and surface oxygen exchange coefficientat <500°C.The newly developed LT-PCECs attain outstanding power densities in fuel cell mode (as high as 0.77 W cm-2 at 450°C), and exceptional current densities in electrolysis mode (over -1.28 A cm-2 at 1.4 V and 450°C). Furthermore, reducing the temperature does not sacrifice the fuel flexibility of these ceramic fuel cells. We demonstrated that the PCECs can directly utilize ammonia and methane for power generation at <500°C. Exceptional durability has been also demonstrated in both fuel cell and electrolysis modes at <500°C.These results further emphasize that through the PCEC scalable manufacturing processes and novel positive electrode materials presented here, PCECs can be employed for power generation and H2 production at <500°C, thereby transforming the architectures and removing previous operational constraints of ceramic electrochemical cells for scaled operation. PCECs can therefore be considered as one part of the growing hydrogen economy, while leveraging the existing fossil fuel infrastructure and achieving higher energy efficiency and lower CO2 emissions.

Inland waterway transport development: A Q-Method study on Tocantins River, Brazilian Amazon

In Brazil, increasing Inland Waterway Transport (IWT) figures among efforts for the Nationally Determined Contribution due to better energy efficiency and lower CO2 emission levels, when compared to highways and railways. Identifying barriers and drivers is useful to develop IWT as an alternative to terrestrial transportation modes, which are scarce in the Brazilian Amazon. As more than 50% of Brazilian electricity is generated in hydropower plants, the harmonic coexistence between multiple water uses is crucial. This paper aims to explore stakeholders' perceptions and priorities related to the development of inland waterway transport in the Tocantins River, Amazon, Brazil, where there are several hydropower plants. With an emphasis on sustainability issues, we used the Q-Method, a technique for assessing the relative importance of elements in various contexts. We identify and describe four perspectives (factors) using Q-method: (1) “critical shoals”; (2) “waterway, death project”; (3) “dams on waterways” and (4) “freedom for waterways”. Within these perspectives, economic incentives, with insights to cut down costs and increase freight are main concerns. We found disconnection between the reality of local communities and the lack of awareness on negative impacts by government officials and economic agents interested in waterway development. Mechanisms to guarantee social participation in IWT planning and implementing could foster socially acceptable solutions for technical, economic and governance issues.

Analysis of energy, exergy and CO2 emissions in a fiberglass furnace with oxy-fuel combustion

Energy savings and emission reductions in the building materials industry are key components of China’s “dual carbon” goals. A new mathematical model of material, energy, exergy, and carbon flows was established and verified against operational data for an 80600 t/y fiberglass furnace in China. The model enables thermal budget calculation along different paths and analysis of the losses and saving potential of the entire fiberglass melting furnace and its three major subsystems. The results indicated that the selected fiberglass furnace attained a satisfactory performance with a specific energy consumption of 4.63 MJ/kg and an energy efficiency of 74.76%. Oxy-fuel combustion provided a substantial overall fuel reduction relative to air combustion. Moreover, the exergy efficiency and effective exergy efficiency reached 62.85% and 55.23%, respectively. The heat recovery system increased the exergy efficiency by 11.01%. Furthermore, the CO2 emissions associated with glass production, major contributors, CO2 reduction potential, and economic impact were obtained. Finally, a sensitivity analysis of the combustion chamber was conducted. This approach could identify the degree of resource and energy utilization and support the implementation of energy and exergy efficiency improvement and CO2 emission reduction schemes.

Conceptual design of full carbon upcycling of CO2 into clean DME fuel: Techno-economic assessment and process optimization

To achieve efficient utilization of CO2 and produce clean alternative fuel, nowadays, CO2-to-DME (CTD) technology is regarded as a feasible and promising solution. Considering that there is no consensus on the techno-economic performances of the different CTD processes, it is necessary to conduct a comprehensive and systematic comparison of the existing and emerging CTD technologies and to deeply explore the influence of the process integration on technical feasibility and economic profitability. In this study, we proposed four CTD processes via different routes, namely purified methanol-mediated (Case 1), water-containing methanol-mediated (Case 2), CO-mediated (Case 3) and direct CO2 hydrogenation routes (Case 4). The rigorous system modelling and comprehensive comparison of the process performances of four cases were implemented. From the technical perspective, Case 4 has the highest energy efficiency (77.42%), exergy efficiency (88.46%), and net CO2 mitigation rate (67.71%). From the economic perspective, Case 2 has the lowest total product cost (1327.14 $/tonne DME), whereas Case 4 has the lowest net CO2 mitigation cost (589.34 $/tonne CO2). Moreover, to further enhance the system performance of Case 4, we also proposed effective improvement measures for process optimization, which shows that the net CO2 mitigation rate is enhanced by 1.94%, while the net CO2 mitigation cost is reduced by 19.79 $/tonne CO2.

Optimizing Operation Strategy in a Simulated High-Proportion Wind Power Wind–Coal Combined Base Load Power Generation System under Multiple Scenes

In order to accommodate more intermittent renewable energy in coal-dominated power systems, conventional thermal power plants need to improve their operational flexibility to balance the energy system at all times. However, flexible operation of coal-fired power plants could reduce energy efficiency and increase CO2 and pollutant emission, so it is important to consider environmental implications and optimize the dispatch of wind and coal power units in the system. In this paper, based on the output profile of wind power, a wind power peak (T, H) simulation model based on Gaussian distribution was established. Using a high-proportion wind power wind–coal combined base load power generation system as an example, the economical and environmentally friendly unit operation based on different wind power penetration was studied by simulation, and the decision strategy was established. Wind energy curtailment boundary was determined with power generation cost, energy consumption, CO2 and pollutant emissions as decision targets, respectively. Weekly scale results indicate that incorporating energy consumption and pollutant emissions into consideration will lead to different decision-making strategies compared with only targeting minimizing wind curtailment. This paper established a decision-making model of wind–coal system operation strategy based on economy and environmental criteria. This work directly contributes to real system operation and is of great significance for future scheduling/dispatch studies of actual power systems.

Energy efficiency improvements and CO2 emission reduction by CNG use in medium- and heavy-duty spark-ignition engines

This research studies the mechanism of improving energy efficiency and reducing CO2 emissions from medium- and heavy-duty spark-ignition engines by replacing gasoline fuels with natural gas. Detailed experimental analyses are conducted on a multi-cylinder research engine using 91RON, 98RON gasoline, and natural gas fuels. Under 7 key operating conditions, energy efficiency breakdown is performed for each fuel to quantify the individual impact of the fuel's carbon content, pumping work, knock tendency, and fuel enrichment. Complete engine mapping is thereafter carried out with all three fuels, and CO2 emissions are compared over the emission certification test cycle. As demonstrated by the test results, the lower carbon content of natural gas is the major contributor to CO2 emission reduction. At idle and part load conditions, engine operation on natural gas shows reduced pumping loss, improved idle stability, and thus increased fuel efficiency. At high load conditions, the greater resistance to knock allows natural gas to operate at optimal combustion phasing. At the peak power condition, the earlier combustion phasing helps to lower exhaust temperatures, thereby avoiding fuel enrichment. With proper calibration, natural gas outperforms its gasoline counterparts to produce 4% better peak power performance and emits 22.5% lower CO2 emissions.

Revisiting energy efficiency and energy related CO2 emissions: Evidence from RCEP economies

Since the last four decades, energy demand has been reached to the utmost level, which also leads to emissions and causes environmental degradation, global warming and climate change all over the world. In this sense, policy makers have suggested various measures including renewable adoption and energy efficiency. Current study aims to investigate the influence of economic growth, energy consumption, renewable electricity output, and energy efficiency on the energy related emissions. A panel of 12 RCEP economies are examined covering the period 1990-2020. Since the data follows irregular path, therefore a novel method of moment panel quantile regression is employed along with the Granger causality test. The empirical results indicate that economic growth and energy consumption significantly enhances energy related emissions, where the magnitude and significance level is found strengthening from lower to upper quantiles (Q0.25, Q0.50, Q0.75 and Q0.90). Conversely, renewable electricity and energy efficiency are the significant tools for lowering energy related emissions in the region. Additionally, a unidirectional causality is found from energy consumption and renewable electricity output to energy related emissions. However, a feedback effect is validated between economic growth, energy efficiency, and energy related emissions. Based on the empirical findings, this study suggests enhancement of renewable electricity output and adoption of energy efficient technologies to reduce environmental degradation and emission level.

Review of energy modelling, energy efficiency models improvement and carbon dioxide emissions mitigation options for the cement industry in South Africa

The cement sector in South Africa contributes approximately 1 % to the South African national greenhouse gas inventory. In line with the country’s GDP increasing which will cause population to increase, the demand for housing, public and private structural infrastructures continues to increase. It is assumed that the demand for cement will also increase proportionally as well as its associated CO2 emission. The purpose of this study is to firstly; review previous energy modelling strategies in South Africa and specifically in the cement industry if any in order to examine the alignment of the cement industry’s strategies with that of the South African government since becoming part of the Paris agreement signatories. Previous studies of energy efficiency, modelling, and GHG emissions were analyzed and reviewed for the understanding of the readiness of South Africa’s cement industry to tackle her energy and global warming issues. South Africa is in a position to tackle the energy efficiency and GHG emissions problem through redesigning and consolidated critical data collection will, driven by the government and responsible stakeholders. Secondly; if any previous strategies are in place but in isolation, to examine the potential for long-term energy efficiency strategies and CO2 mitigation options for the cement sector in South Africa; as these two elements have a distinguishable link. Cement production is an energy-intensive process that consists of combustion-and process-related emissions. This study will employ-two modelling frameworks to examine strategies for reducing cement sector energy demand and associated CO2 emission for the period 2015 to 2050 (35 years) with 5-year intervals parallel to the Paris agreement. After reviewing energy models, the study will employ the low emissions analysis platform (LEAP) to model possible energy saving methods in the combustion process and other forms of energy supply in the context of South African cement sector. The existing reviewed methods and results will be compared and the LEAP will provide a second set of comparable results in order to influence policy and inform decision-making. For process-related emissions in the sector, the study will develop an excel-based model to examine possible strategies for reducing CO2 emission in the sector. The results will be examined in terms of cumulative energy savings, GHG emissions, and marginal abatement cost of carbon.

Optimization-based framework for technical, economic, and environmental performance assessment of CO2 utilization strategies

Carbon capture and utilization (CCU) for chemicals and fuel production is one of the effective measures addressing global warming and energy security. Since CCU utilizes harmful CO2 as a raw material to produce high-value chemicals and fuels such as methanol, Fischer-Tropsch fuel, dimethyl ether, and gasoline, it mitigates CO2 emission and creates more fuel availability or shares the burden on fossil fuels. This study aims to develop an optimization-based framework of CO2 utilization strategies and to analyze CO2-to-fuel strategies regarding technical, economic, and environmental performance. To achieve this goal, we generated a superstructure consisting of many CO2 utilization pathways, including a series of technologies (e.g., reaction/conversion, and separation and purification) for different fuel production. We then developed process simulation and estimated the key techno-economic parameters such as mass and energy flow, and sizing and costing data. The optimization models were developed to identify the optimal CO2 utilization strategy and assess its feasibility with four different criteria: energy efficiency (EEF), production quantity, production cost (UPC), and net CO2 emission (NCE). As a result, the proposed optimization-based framework is able to i) identify the best CO2 utilization strategy over various technological pathways for targeted fuels, ii) provide a decision-making guide to policymakers and stakeholders for planning an economically viable and sustainable CO2 utilization strategy.

Baseline design of a subsea shuttle tanker system for liquid carbon dioxide transportation

This paper presents the baseline design of a 34,000-tonne subsea shuttle tanker (SST). The SST is proposed as an alternative to subsea pipelines and surface tankers for the transportation of liquid carbon dioxide (CO2) from existing offshore/land facilities to marginal subsea fields. In contrast to highly weather-dependent surface tanker operations, the SST can operate in any condition underwater. The SST is an electric-powered autonomous underwater vehicle with a length and beam of 164 m and 17 m, respectively. It has a cargo carrying capacity of 16,362 m3. This capacity is sufficient to allow the SST to fulfil the annual storage demands of ongoing carbon capture and storage (CCS) projects in Norway. It travels with a slow speed of 6 knots at 70 m constant water depth for maximum energy efficiency and offloads CO2 via a connected coupling to the subsea well where CO2 is directly injected. To be economically attractive, the SST has a high payload of 50% displacement which makes a low structural weight design extremely crucial. This is achieved by employing a double hull design for the SST with active pressure compensating systems to cope with the large collapse pressure loads underwater.

Bottom-up analysis of energy efficiency improvement and CO2 emission reduction potentials in the cement industry for energy transition: An application of extended marginal abatement cost curves

Demand-side energy savings are crucial to the on-going global energy transition. As the third-most energy-intensive sector and a major contributor to CO2 emissions, the cement industry has considerable potential for energy savings and CO2 abatement in Taiwan. This potential is conventionally measured using marginal abatement cost curves (MACCs), which are inherently flawed. When presented with multiple measures with the same negative cost, conventional MACCs tend to favour measures that produce small reductions in CO2 emissions over measures with larger reductions. In the current study, we investigated energy savings and CO2 abatement using an extended energy conservation supply curve (ECSC) and an extended MACC. The technical potential energy savings and CO2 abatement were respectively estimated at 5.98% of the sector’s final energy use and 3.88% of CO2 emissions in 2018. Overall, 51.2% of the electricity savings and 92.5% of fuel savings could be implemented cost-effectively. In the proposed approach, priority is given to cost-effective measures with the greatest potential in terms of energy savings and CO2 abatement. Our results help to elucidate the issue of energy efficiency in the cement industry, and provide a valuable reference for the formulation of effective energy policy.

Transformation of CO2 into liquid fuels and synthetic natural gas using green hydrogen: A comparative analysis

The power-to-liquids (P2L) and power-to-gas (P2G) processes which utilize renewable power to convert carbon dioxide and water into value-added syncrude and synthetic natural gas have recently gained much attention as an efficient way for CO2 mitigation. Based on our previously proposed direct P2L and P2L/P2G hybrid processes in the absence of the reverse-water–gas-shift unit, in this work, we developed the indirect P2L and P2L/P2G hybrid processes combined with the reverse-water–gas-shift unit, which produce solely syncrude and the combination of syncrude and synthetic natural gas, respectively. A comparative study of the indirect and direct P2L and P2L/P2G hybrid processes via the process modelling and techno-economic analysis was implemented to quantitatively evaluate their process performance differences, and it was indicated that the indirect P2L and P2L/P2G hybrid processes were also able to be considered as suitable technologies for the transformation of CO2 into high-value hydrocarbons, and the indirect P2L/P2G hybrid process seemed to be more competitive than the indirect P2L process from both technical and economic aspects. Moreover, compared to the direct P2L and P2L/P2G hybrid processes, the indirect P2L and P2L/P2G hybrid processes produce more syncrude, however, they are less efficient in aspects of energy efficiency and net CO2 reduction.

Renewable Energy Utilization in Rural Residential Housing: Economic and Environmental Facets

Energy and climate policies benefit from modernized construction technology and energy supply source choices. Energy-efficiency improvement and CO2 emission reduction will result from renewable energy (RE) utilization in new and retrofit single-family houses in rural Poland. Several house construction scenarios and heating energy sources comparing building costs and potential emission reduction are based on already existing structures calculated for a 100 m2 dwelling corresponding to the average rural home. With the addition of thermal insulation and RE-generating equipment, construction costs increase, but the energy costs of operating the home dramatically shrink between a conventional and energy-neutral house. The latter scenario includes thermal solar panels and a heat pump as heating energy sources as well as electricity-generating PV panels. Replacing coal with environmentally-friendly RE reduces CO2 emissions by about 90% annually. Additionally, lower dependence on coal lessens other GHG emissions leading to immediate air quality improvement. New house building regulations guide homeowner construction and heating energy choice, but even larger gains could result from retrofitting existing rural houses, expanding environmental benefits and generating energy bill savings to households. However, the varying climate throughout Poland will require the purchase of energy in winter to assure residents’ comfort.

Waste heat recovery from a data centre and 5G smart poles for low-temperature district heating network

The city of Espoo, Finland is planning to develop Kera as a green suburb with high level of energy efficiency and low CO2 emissions, using a high share of renewable energy and recycled or reused energy. For reaching this target, in this study, renewable energy resources such as solar, wind and waste heat are investigated for the study region. Two different technologies comprising heat pump (HP) and heat-only boiler (HOB) are investigated to retrieve waste heat from a data centre and LuxTurrim5G smart poles to use in a low-temperature district heating network. We investigate various scenarios to supply the required energy for the HP (which receives electricity from the electricity market, photovoltaic (PV) system, wind turbine (WT) and hybrid PV/WT; 4 scenarios) and HOB (which works with electricity, forest fuel wood, biogas, ammonia, wood pellets and industry wood residue; 6 scenarios). We found that the heat pump scenario is an efficient and cost-effective way to retrieve waste heat from the data centre and 5G smart poles with an LCOE of 3.192 ¢/kWh if electricity is produced by the PV system, and 3.516 ¢/kWh when the heat pump receives its electricity only from the electricity market.

Assessment of CO2 emissions for a bulk carrier fleet

Recently, international regulations have started to come into force due to increasing of carbon dioxide (CO2) emissions as a greenhouse gas emission from ships. There are two important emission regulations which are European Union Monitoring, Reporting and Verification (EU-MRV) and International Maritime Organization Data Collection System (IMO DCS) as a Ship Energy Efficiency Management Plan (SEEMP) Part 2, became valid from 2018 to 2019, respectively. Both EU MRV and IMO DCS regulations are mandatory for the ships above 5000 GRT and examine CO2 emissions related to international shipping. Within this framework, the aim of this article involves to guide the shipping companies about energy efficiency and environmental management with comparing energy efficiency measures as novel Fleet Energy Efficiency Management Index (FEEMI), CO2 emissions, CO2 index and Energy Efficiency Operational Indicator (EEOI) values.In this study, firstly, operational energy efficiency values have been analyzed with a voyage details of five bulk carrier ships to assess the possible reasons of the changings by the years of 2017 and 2018. Furthermore, FEEMI have been defined as a novel energy efficiency indicator to evaluate the performance of the shipping companies. Lastly, different scenarios have been carried out to observe the effects of cargo carried capacity and fuel consumption amount on EEOI. As numerical results, the highest CO2 emissions and index values are found for ship C1 as 29,676 tonnes and 54,592 tonnes with 433 × 10−3 tonnesCO2/nmile and 449 × 10−3 tonnesCO2/nmile for the years of 2017 and 2018, respectively. Besides, the lowest energy efficiency operational indicator (EEOI) are calculated for ship C1 as 4.43 × 10−6 tonnesCO2/MT.nmile and 5.06 × 10−6 tonnesCO2/MT.nmile for the years of 2017 and 2018, respectively.

Chloroplast-like porous bismuth-based core–shell structure for high energy efficiency CO2 electroreduction

Electrochemical CO2 reduction reaction (CO2RR) to formate is economically viable considering the energy input and market value. Through learning nature, a series of chloroplast-like porous bismuth-based core–shell (CPBC) materials have been designed. In these materials, the porous carbon can enrich and transfer CO2 to the core–shell Bi@Bi2O3 in CO2 reduction process, during which Bi2O3 layer can be transformed into activated metastable layer to efficiently convert CO2 into formate and Bi can provide abundant electrons. Based on this, superior performances for most of important parameters in CO2RR can be achieved and best of them, CPBC-1 presents remarkable Faradaic efficiency (FEformate > 94%) over a wide potential range (−0.65 to −1.0 V) with high catalysis durability (>72 h). Noteworthy, its maximum energy efficiency is as high as 76.7% at −0.7 V, the highest one in reported bismuth-based materials. This work opens novel perspectives in designing nature-inspired CO2RR electrocatalysts.

Variability in Measured Real-World Operational Energy Use and Emission Rates of a Plug-In Hybrid Electric Vehicle

Compared to comparably sized conventional light duty gasoline vehicles (CLDGVs), plug-in hybrid electric vehicles (PHEVs) may offer benefits of improved energy economy, reduced emissions, and the flexibility to use electricity as an energy source. PHEVs operate in either charge depleting (CD) or charge sustaining (CS) mode; the engine has the ability to turn on and off; and the engine can have multiple cold starts. A method is demonstrated for quantifying the real-world activity, energy use, and emissions of PHEVs, taking into account these operational characteristics and differences in electricity generation resource mix. A 2013 Toyota Prius plug-in was measured using a portable emission measurement system. Vehicle specific power (VSP) based modal average energy use and emission rates are inferred to assess trends in energy use and emissions with respect to engine load and for comparisons of engine on versus engine off, and cold start versus hot stabilized running. The results show that, compared to CLDGVs, the PHEV operating in CD mode has improved energy efficiency and lower CO2, CO, HC, NOx, and PM2.5 emission rates for a wide range of power generation fuel mixes. However, PHEV energy use and emission rates are highly variable, with periods of relatively high on-road emission rates related to cold starts.