Substantial Emission Reductions Research Articles

Contribution of the Greenland Ice Sheet to sea level over the next millennium.

The Greenland Ice Sheet holds 7.2 m of sea level equivalent and in recent decades, rising temperatures have led to accelerated mass loss. Current ice margin recession is led by the retreat of outlet glaciers, large rivers of ice ending in narrow fjords that drain the interior. We pair an outlet glacier-resolving ice sheet model with a comprehensive uncertainty quantification to estimate Greenland's contribution to sea level over the next millennium. We find that Greenland could contribute 5 to 33 cm to sea level by 2100, with discharge from outlet glaciers contributing 8 to 45% of total mass loss. Our analysis shows that uncertainties in projecting mass loss are dominated by uncertainties in climate scenarios and surface processes, whereas uncertainties in calving and frontal melt play a minor role. We project that Greenland will very likely become ice free within a millennium without substantial reductions in greenhouse gas emissions.

Operation of a 50-kWth chemical looping combustion test facility under autothermal conditions

The United States Department of Energy is developing transformational fossil fuel combustion technologies that result in more efficient power cycles and/or substantial reductions in GHG emissions. Chemical Looping Combustion (CLC) has the potential to achieve a lower cost of electricity than a supercritical pulverized coal power plant with an amine absorption system. Although the concept and research on chemical looping has a long history, CLC has numerous technical issues that must be addressed prior to a commercial debut. This effort is directed toward the following major issues for CLC: (1) demonstrating continuous solids handling, operability, and reactor performance at autothermal conditions and (2) preliminary assessments of oxygen carrier attrition and relative material make-up costs. These are critical issues that should be addressed under realistic conditions prior to directing resources toward larger scale demonstrations. This paper will also describe NETL’s small 50-kWth natural gas circulating CLC test facility located in Morgantown, WV. Despite its small size, this experimental test unit has operated at autothermal conditions for 11 h using a copper-iron-alumina oxygen carrier developed at NETL. This paper will describe the test facility and operating experiences using NETL’s “Gen 2.0” oxygen carrier material. Natural gas conversion to CO2 ranged from 70 to 90% over approximately 75 oxidation-reduction cycles during the autothermal operating period. Estimates for the process specific attrition rate during autothermal operation are also presented. Finally, estimates for the oxygen carrier makeup cost, specific to the NETL process configuration, are several orders of magnitude greater than the NETL target. Future work should focus on reducing the oxygen carrier material cost and improving the attrition resistance of the oxygen carrier material under autothermal test conditions.

Performance evaluation of the VITROS® hs Troponin I assay⁎ on the VITROS® ECi/ECiQ and 3600 immunodiagnostic and VITROS® 5600/XT 7600 integrated systems

A large part of the European population is still exposed to ambient nitrogen dioxide (NO2) levels exceeding the European Union (EU) air quality standards, being a key challenge to reduce NO2 concentrations across many European urban areas, particularly close to roads. In this work, a trend analysis of pollutants involved in NO2 processes was done for the period 2003–2014 in traffic sites from three Spanish cities (Barcelona, Madrid and Granada) that still exceed the European NO2 air quality standard limits. We also estimated the contributions of primary NO2 emissions and photo-chemically formed NO2 to the observed ambient NO2 concentrations in order to explore their possible role in the observed NO2 concentration trends. The NOx and NO concentrations at these traffic sites showed significant decreasing trends during the period 2003–2014, especially at Barcelona (BARTR) and Madrid (MADTR) traffic stations. The NO2 concentrations showed statistically significant downward trends at BARTR and MADTR and remained unchanged at Granada traffic station (GRATR) during the study period. Despite the significant decrease in NO2 concentrations in BCNTR and MADTR during the analysed period, the NO2 concentrations observed over these sites still above the annual NO2 standard limit of 40 μg m−3 and, therefore, more efficient measures are still needed. Primary NO2 emissions significantly influence NO2 concentrations at the three analysed sites. However, as no drastic changes are expected in the after-exhaust treatment technology that can reduce primary NO2 emissions to zero in the near future, only a substantial reduction in NOx emissions will help to comply with the NO2 European air quality standards. Reduction of 78%, 56% and 16% on NOx emissions in Barcelona, Madrid and Granada were estimated to be necessary to comply with the NO2 annual limit of 40 μg m−3.

An optimized graphene oxide self-assembly surface for significantly enhanced boiling heat transfer

The enhancements in boiling heat transfer, i.e., critical heat flux (CHF) and heat transfer coefficient (HTC) can bring immediate benefits to improve the safety, efficiency and cost of heat energy transfer and conversion systems, leading to substantial global energy savings and reduction in greenhouse gas emissions. The enhanced boiling surfaces with great durability are highly desired for energy-intensive industrial applications. Here an optimized graphene oxide (GO) self-assembly surface for significantly enhanced boiling is developed, which could be readily fabricated utilizing the nucleate boiling self-assembly method. The optimal GO boiling surface produces remarkable improvements in boiling heat transfer performance (a CHF of 261 W cm-2 and a HTC of 9.1 W cm-2 K−1), which is among the highest values ever reported for pool boiling heat transfer on the planar enhanced surfaces. Additionally, it shows a good durability. The prominent performance can be attributed to the formation of interconnected and highly thermally conductive GO laminate film with moderate thickness on the substrate, which facilitates rapid cooling and rewetting of the local hot/dry regions, as well as bubble nucleation, thereby delay the occurrence of film boiling regime. The proposed strategy in current work is highly scalable and possesses enormous potentials in pragmatic applications.

Approaches for More Efficient Biological Conversion of Lignocellulosic Feedstocks to Biofuels and Bioproducts

The future bioeconomy promises drop-in or performance-advantaged biofuels and bioproducts derived from lignocellulosic biomass, substantial greenhouse gas emissions reductions in sectors with few or no alternatives, and increased domestic energy production in countries with sufficient biomass resources. Despite the slower than anticipated pace of commercializing next-generation biofuels, the research community continues to make dramatic improvements at every stage of production, from feedstock cultivation through conversion to final products. However, the interdisciplinary nature of bioenergy research, and the need for cross-coordination among biologists, chemists, agronomists, and engineers, make coordinating and optimizing these strategies challenging. This Perspective surveys recent advancements in bioenergy crop engineering, lignocellulosic biomass deconstruction and fractionation, catabolism of biomass-derived sugars and aromatics, and biological conversion to fuels and products. We organize major research approaches into broad categories and comment on which strategies offer synergies or trade-offs in the context of four approaches to improving the economics and carbon-efficiency of advanced biofuels and bioproducts: (1) maximize sugar conversion to a single product, (2) utilize diverse carbon sources for producing a single product, (3) convert lignin to high-value products, and (4) fractionate the hydrolysate to derive maximum value from each component.

What would it take for renewably powered electrosynthesis to displace petrochemical processes?

Electrocatalytic transformation of carbon dioxide (CO2) and water into chemical feedstocks offers the potential to reduce carbon emissions by shifting the chemical industry away from fossil fuel dependence. We provide a technoeconomic and carbon emission analysis of possible products, offering targets that would need to be met for economically compelling industrial implementation to be achieved. We also provide a comparison of the projected costs and CO2 emissions across electrocatalytic, biocatalytic, and fossil fuel-derived production of chemical feedstocks. We find that for electrosynthesis to become competitive with fossil fuel-derived feedstocks, electrical-to-chemical conversion efficiencies need to reach at least 60%, and renewable electricity prices need to fall below 4 cents per kilowatt-hour. We discuss the possibility of combining electro- and biocatalytic processes, using sequential upgrading of CO2 as a representative case. We describe the technical challenges and economic barriers to marketable electrosynthesized chemicals.

Greener and Fairer: A Progressive Environmental Tax Reform for Spain

Environmental externalities call for the use of environmental taxes to get prices right and thereby reduce environmental pressures. To date, however, the Spanish government makes only limited use of environmental taxes. One major reason for the policy reluctance are concerns on the regressive impacts of environmental taxes. We argue that policy can hedge against these concerns by means of revenue recycling. More specifically, we assess the impacts of a green tax reform where additional revenues are redistributed lump-sum to Spanish households on an equal-per-capita basis. Based on quantitative evidence from coupled microsimulation and computable equilibrium analyses we find that such a green tax reform leads to a substantial reduction in harmful emissions while having a progressive impact.

Optimum Turf Grass Irrigation Requirements and Corresponding Water- Energy-CO2 Nexus across Harris County, Texas

Harris County is one of the most populated counties in the United States. About 30% of domestic water use in the U.S. is for outdoor activities, especially landscape irrigation and gardening. Optimum landscape and garden irrigation contributes to substantial water and energy savings and a substantial reduction of CO2 emissions into the atmosphere. Thus, the objectives of this work are to (i) calculate site-specific turf grass irrigation water requirements across Harris County and (ii) calculate CO2 emission reductions and water and energy savings across the county if optimum turf grass irrigation is adopted. The Irrigation Management System was used with site-specific soil hydrological data, turf crop water uptake parameters (root distribution and crop coefficient), and long-term daily rainfall and reference evapotranspiration to calculate irrigation water demand across Harris County. The Irrigation Management System outputs include irrigation requirements, runoff, and drainage below the root system. Savings in turf irrigation requirements and energy and their corresponding reduction in CO2 emission were calculated. Irrigation water requirements decreased moving across the county from its north-west to its south-east corners. However, the opposite happened for the runoff and excess drainage below the rootzone. The main reason for this variability is the combined effect of rainfall, reference evapotranspiration, and soil types. Based on the result, if the average annual irrigation water use across the county is 25 mm higher than the optimum level, this will result in 10.45 million m3 of water losses (equivalent water use for 30,561 single families), 4413 MWh excess energy use, and the emission of 2599 metric tons of CO2.

It starts at home? Climate policies targeting household consumption and behavioral decisions are key to low-carbon futures

Through their consumption behavior, households are responsible for 72% of global greenhouse gas emissions. Thus, they are key actors in reaching the 1.5 °C goal under the Paris Agreement. However, the possible contribution and position of households in climate policies is neither well understood, nor do households receive sufficiently high priority in current climate policy strategies. This paper investigates how behavioral change can achieve a substantial reduction in greenhouse gas emissions in European high-income countries. It uses theoretical thinking and some core results from the HOPE research project, which investigated household preferences for reducing emissions in four European cities in France, Germany, Norway and Sweden. The paper makes five major points: First, car and plane mobility, meat and dairy consumption, as well as heating are the most dominant components of household footprints. Second, household living situations (demographics, size of home) greatly influence the household potential to reduce their footprint, even more than country or city location. Third, household decisions can be sequential and temporally dynamic, shifting through different phases such as childhood, adulthood, and illness. Fourth, short term voluntary efforts will not be sufficient by themselves to reach the drastic reductions needed to achieve the 1.5 °C goal; instead, households need a regulatory framework supporting their behavioral changes. Fifth, there is a mismatch between the roles and responsibilities conveyed by current climate policies and household perceptions of responsibility. We then conclude with further recommendations for research and policy.

The effects of carbon taxation in China: An analysis based on energy input-output model in hybrid units

This paper evaluates the economy-wide effects of carbon taxation in China. To this end, we build a price model based on an energy input-output table in hybrid units that ensures the consistency of the analysis. The results indicate that carbon taxation has small negative impact on GDP. There are, however, relatively substantial emissions reductions. To explore whether the impacts are spatially blind, in the sense of having similar impacts on urban and rural residents, the results of the distributional effects show that the impacts of carbon taxation on different urban household groups reveal small differences and are slightly regressive. Yet for rural residents, carbon taxation may be significantly regressive. In addition, rural residents are found to be affected much more than urban residents. Furthermore, the paper explores a policy intervention to investigate the effects of redistributing the carbon tax paid by households. The main results reveal that reallocating the carbon tax to the groups with low income levels can offset the negative distributional effects significantly. Moreover, the results of Miyazawa-style interrelational income multiplier analysis indicate that the household groups with high income would benefit significantly from the income increases in those with low income levels, but not vice versa.

Long-term trends (2005–2016) of source apportioned PM2.5 across New York State

The United States has experienced substantial air pollutant emissions reductions in the last two decades. Among others, emissions produced by electricity generation plants and industries were significantly lowered. Ultralow (<15 ppm) sulfur fuels were introduced for road vehicles, nonroad, rail, and maritime transport. New heavy-duty diesel trucks have been equipped with particle traps and NOx controls. Residual oil (No. 6) for space heating and for any other purpose was replaced with cleaner No. 2 and No. 4 oils. Chemical speciation of PM2.5 has been measured since 2005 at eight sites across the New York State. A prior study has identified and apportioned the major sources of PM2.5 across the State using receptor modelling (positive matrix factorization). This present study aims to investigate the long-term trends of those source-apportioned PM2.5 mass contributions from 2005 to 2016 at the eight sites: two rural sites (Pinnacle and Whiteface), three medium sized cities (Buffalo, Albany, Rochester), and three sites in the New York City metropolitan area (Bronx, Manhattan and Queens). Negative trends from 2005 to 2016 were detected across the state for secondary sulfate (from −0.19 μg/m3/y in Rochester to −0.36 μg/m3/y at BRO and QUE) and secondary nitrate (from −0.02 μg/m3/y at the rural sites to approximately −0.2 μg/m3/y at BRO and MAN). Spark-ignition vehicles were the only source type experiencing upward annual trends at all urban sites with slopes ranging from 0.02 μg/m3/y (ROC, not statistically significant) to ∼0.2 μg/m3/y (Albany, Bronx, Manhattan). Other sources exhibited different trends among the sites. The relationships of source contributions with emissions inventories were explored with regression analysis. A new trajectory model, differential concentration-weighted trajectories (DCWT), was used to examine spatial changes in sources of secondary aerosol affecting the rural sites.

Cooperative R&amp;amp;d Investments and R&amp;amp;d Costs Recovery: Climate Change Treaties with a Breakthrough Technology

This paper examines the climate change treaties with cooperative R&D that brings about substantial reduction in greenhouse gas emission. By developing a joiner’s gain function, we present a new approach under which countries that have invested in R&D can recover their R&D costs by breakthrough technology. Additionally, we set a new assumption that R&D costs decrease if countries collectively address R&D. If cooperative R&D efficiency is effective, recovery of R&D costs promotes further technological innovation and the broad participation in treaty.

Effect of global atmospheric aerosol emission change on PM2.5-related health impacts

ABSTRACTBackground: Previous research has highlighted the importance of major atmospheric aerosols such as sulfate, through its precursor sulfur dioxide (SO2), black carbon (BC), and organic carbon (OC), and their effect on global climate regimes, specifically on their impact on particulate matter measuring ≤ 2.5 μm (PM2.5). Policy regulations have attempted to address the change in these major active aerosols and their impact on PM2.5, which would presumably have a cascading effect toward the change of health risks.Objective: This study aimed to determine how the change in the global emissions of anthropogenic aerosols affects health, particularly through the change in attributable mortality (AN) and years of life lost (YLL). This study also aimed to explore the importance of using AM/YLL in conveying air pollution health impact message.Methods: The Model for Interdisciplinary Research on Climate was used to estimate the gridded atmospheric PM2.5 by changing the emission of SO2, BC, and OC. Next, the emissions were utilized to estimate the associated cause-specific risks via an integrated exposure–response function, and its consequent health indicators, AM and YLL, per country.Results: OC change yielded the greatest benefit for all country income groups, particularly among low-middle-income countries. Utilizing either AM or YLL did not alter the order of benefits among upper-middle and high-income countries (UMIC/HIC); however, using either health indicator to express the order of benefit varied among low- and low-middle-income countries (LIC/LMIC).Conclusions: Global and country-specific mitigation efforts focusing on OC-related activities would yield substantial health benefits. Substantial aerosol emission reduction would greatly benefit high-emitting countries (i.e. China and India). Although no difference is found in the order of health outcome benefits in UMIC/HIC, caution is warranted in using either AM or YLL for health impact assessment in LIC/LMIC.

Real-world gaseous emissions of high-mileage taxi fleets in China

Mileage of taxi fleets is significantly higher than regular passenger vehicles in China, which might trigger greater tailpipe emissions of air pollutants. To investigate their real-world gaseous emissions, we applied portable emissions measurement systems (PEMSs) to test 44 gasoline and 24 bi-fuel taxis in seven cities. Our real-world measurement results indicated that a major part of the tested China 3 and China 4 gasoline taxis, especially the samples with high mileage (>300,000 km), far exceeded the corresponding emission limits of NOX, THC and CO. Only the newest China 5 gasoline taxis with relatively lower mileage had effective emission controls and the gaseous emissions were below the limits. Illegal tampering, malfunction and deterioration of three-way catalytic converters (TWC) are major reasons for high emissions from high-mileage taxis. First, China 4 gasoline taxis without TWC (purposely removed by drivers) increased their gaseous emissions than TWC-equipped counterparts by more than one order of magnitude. Second, bi-fuel taxis when using compress natural gas (CNG) had much higher NOX and THC emissions than those when using gasoline, which might be probably attributed to unsophisticated engine calibration and unfavorable TWC working conditions. Furthermore, TWC renewal could bring immediate and substantial emission reductions (up to 70%) for high-mileage taxis. However, such benefits from TWC renewal would become less significant as the mileage levels further increase. We also found a good correlation between CO and THC emissions for gasoline taxis, whose cold start effects were both significant. This study poses significant concerns regarding real-world emissions of high-mileage taxi fleets in China, which could consist of many gross emitters in the urban areas. Stringent in-use compliance programs and in particular frequent TWC renewals for high-mileage taxis should be implemented by policy makers in China.

The diminishing importance of nitrogen dioxide emissions from road vehicle exhaust

The direct emission of nitrogen dioxide (NO2) from road vehicle exhaust has been an important contributor to near-road ambient concentrations of NO2 in many European cities. Diesel vehicles and their use of emission control technologies such as Diesel Oxidation Catalysts, have dominated the emission of NO2 from road vehicles. In this work, we summarise findings from recent vehicle emission remote sensing measurements in the UK that provide detailed information on the emissions of NO2 and total NOx(NO2 + NO). We show that while new diesel cars and light commercial vehicles are associated with high (typically 30%) proportions of NO2/NOx, the amount of absolute NOx and NO2 emitted by most Euro 6 vehicles has decreased substantially and that absolute emissions of NO2 have been reducing since around 2007. Additionally, we find that the amount of NO2 decreases as the vehicle mileage increases. Taken together, these factors have led to substantial reductions in emissions of NO2 in recent years from light duty diesel vehicles, which has contributed to reduced roadside NO2 concentrations. There is a need however for commonly used emission factor models to account for these changes in emissions of NO2.

Chemometric methods for source apportionment of 210Pb, 210Bi and 210Po for 10 years of urban air radioactivity monitoring in Lodz city, Poland

The radionuclide activity concentrations of 210Pb and its decay products 210Bi and 210Po were measured in 271 total suspended particulate samples collected from 2008 to 2017 in the center of Lodz city, Poland. Natural and anthropogenic contributions to the observed activities of 210Pb, 210Bi and 210Po radionuclides were estimated. Corrected aerosol residence times were determined for this purpose. After the closure of one of the coal-fired power plants located in the center of the city, a substantial reduction in emission of these radionuclides was observed. For proper identification of the origins of these radionuclides, the concentrations of 4 K and 7Be as well as sulfur dioxide (SO2), and total air particulate matter were measured. Principal component analysis and cluster analysis were conducted for source apportionment of 210Pb, 210Bi and 210Po in urban air.

Hybrid renewable energy systems for household ancillary services

The development of Hybrid Renewable Energy Systems (HRES) under the Distributed Generation (DG) paradigm is the support for substantial reduction of CO2 emissions and for greater penetration of renewable energy sources. The performance and reliability of HRES depend on the interaction between demand, generation, storage and the energy management strategy. In this study a comparison between two different control strategies is presented. In particular, a Rule Based Control (RBC) strategy has been compared with a more sophisticated Model Predictive Control (MPC) for the management of an HRES for residential applications.Results show that a HRES operating in a connected mode has potential to support grid balancing actions giving economic benefits for both end-users and providers. Moreover, the MPC strategy gives a potential reduction of the unbalanced energy exchange with the grid and a more efficient use of the HRES components. The MPC strategy allows thus for a more effective use of renewable sources if compared with a conventional RBC for a Microgrid of same size, thus allowing for a greater penetration of renewable sources into the energy mix, or equivalently, toward downsizing of storage and programmable source subsystems with economic benefits.

Areas under high ozone and nitrogen loads are spatially disjunct in Czech forests

It is widely accepted that excessive loads of nitrogen (N) deposition and ambient ozone (O3) endanger natural ecosystems and the environment. Despite substantial reductions in emissions since the early 1990s both in the Czech Republic and in neighbouring countries, neither O3 exposures nor N deposition have yet decreased to acceptable levels relative to the recommended thresholds. Based on long-term monitoring and high-quality data, we have indicated the areas of special risk due to high N deposition and O3 exposures in Czech forests in 2000–2015. The areas of potential risk denote those forests under the highest loads of N deposition and O3 exposure on a regular basis. The underlying classification approach is relativistic, i.e. based ultimately on quartiles of pollution intensities and not derived from critical limits or loads. The forest areas under the highest O3 exposures and N deposition are spatially disjunct. The highest O3 exposures are in the southern and the highest N deposition is in the northern Czech Republic. In contrast to our assumption, only 1322 km2, i.e. 4.6% of the total forested area (28,782 km2) are overlapping areas with a potential risk due both to high O3 exposures and to N deposition. Our results provide valuable input information for a more detailed environmental analysis, anticipated in the future, addressing to what extent the indicated areas at potential risk are associated with the actual negative impacts on forests.

Do Mandatory Energy Audits Reduce Building Energy Use?: A Bayesian Analysis of New York City's Local Law 87

Cities are experimenting with a range of policy and regulatory tools to reduce energy use in the building sector as a pathway to substantial carbon emission reductions. Increasingly, cities are turning to policies that reduce information asymmetries and knowledge gaps through data transparency, focusing on existing buildings and the potential to achieve up to 50% energy savings through retrofit adoption. These include energy disclosure - or benchmarking - ordinances and, more recently, mandatory energy audit requirements. While energy benchmarking is a relatively low-cost mandate, energy audits impose non-trivial costs in terms of capital and time for building owners. The question we explore here is whether mandatory energy audits lead to reduced energy consumption over time. We collect detailed energy use and building attribute data from 2011 to 2016 for approximately 4,000 buildings in New York City and integrate with a unique dataset of mandatory energy audit reports for a randomly selected sample conducted in 2013 and 2014. We use non-parametric statistical tests and Bayesian regression to evaluate the impact of energy audits on building energy performance, compared to a control group of matched buildings not subject to the audit requirement. We find that mandatory energy audits have a modest negative impact on energy consumption, consistent with savings expected from low-cost energy conservation measures and retro-commissioning activities. The result reinforces the hypothesis that audits, by themselves, create an insufficient incentive to invest in energy efficiency upgrades at the scale needed to meet city carbon reduction goals.

Development and analysis of strategies to facilitate the conversion of Canadian houses into net zero energy buildings

Canada has numerous climatic and geographical regions and the Canadian housing stock (CHS) is diversified in terms of vintage, geometry, construction materials, envelope, occupancy, energy sources and heating, ventilation and air conditioning system and equipment. Therefore, strategies to achieve net zero energy (NZE) status with the current stock of houses need to be devised considering the unique characteristics of the housing stock, the economic conditions and energy mix available in each region. Identifying and assessing pathways for converting existing houses to NZE buildings at the housing stock level is a complex and multifaceted problem and requires extensive analysis on the impact of energy efficiency and renewable/alternative energy technology retrofits on the energy use and GHG emissions of households.A techno-economic analysis of retrofitting renewable/alternative energy technologies in the CHS to reduce energy consumption and GHG emissions was conducted to develop strategies to achieve or approach NZE status for Canadian houses. The results indicate that substantial energy savings and GHG emission reductions are techno-economically feasible for the CHS through careful selection of retrofit options. While achieving large scale conversion of existing houses to NZEB is not feasible, approaching NZE status is a realistic goal for a large percentage of Canadian houses.