Drought impacts on the electricity system, emissions, and air quality in the western United States.

The western United States has experienced severe drought in recent decades, and climate models project increased drought risk in the future. This increased drying could have important implications for the region's interconnected, hydropower-dependent electricity systems. Using power-plant level generation and emissions data from 2001 to 2021, we quantify the impacts of drought on the operation of fossil fuel plants and the associated impacts on greenhouse gas (GHG) emissions, air quality, and human health. We find that under extreme drought, electricity generation from individual fossil fuel plants can increase up to 65% relative to average conditions, mainly due to the need to substitute for reduced hydropower. Over 54% of this drought-induced generation is transboundary, with drought in one electricity region leading to net imports of electricity and thus increased pollutant emissions from power plants in other regions. These drought-induced emission increases have detectable impacts on local air quality, as measured by proximate pollution monitors. We estimate that the monetized costs of excess mortality and GHG emissions from drought-induced fossil generation are 1.2 to 2.5x the reported direct economic costs from lost hydro production and increased demand. Combining climate model estimates of future drying with stylized energy-transition scenarios suggests that these drought-induced impacts are likely to remain large even under aggressive renewables expansion, suggesting that more ambitious and targeted measures are needed to mitigate the emissions and health burden from the electricity sector during drought.

Atopic dermatitis in early life and pain at 10 years of age: An exploratory study.

Pain is a distinctive burden in atopic dermatitis and recognized as an important and highly prevalent symptom. It is unknown if the presence of atopic disease may sensitize children to adverse pain profiles in the long term. We aimed to assess the impact of early-life atopic dermatitis-like symptoms on pain at 10 years of age. We used data from 1302 and 874 participants of the Generation XXI birth cohort evaluated at 6 and 15 months, respectively, and 10 years. Atopy-like symptoms since birth, including atopic dermatitis, were collected at ages 6 and 15 months by interviewing parents. Pain history in the last 3 months at age 10 was collected from parents and children using structured questionnaires. We computed relative risks (RR) and respective 95% confidence intervals of pain features at age 10 according to each atopic-like symptom at 6 and 15 months. Children whose parents reported atopic dermatitis-like symptoms at 6 months and at 15 months had higher risk of reporting any pain (RR 1.75 [1.15-2.66]) and multisite pain, respectively (RR 1.67 [1.18-2.37]) at 10 years of age.  Conclusion: Atopic dermatitis symptoms in early life were associated with a higher risk of pain at age 10, suggesting that potential for sensitization during the first decade of life and highlighting the importance of improving the health care of children with atopic dermatitis is worth investigating. What is Known: • Atopic disorders have been associated with many non-atopic comorbidities, including chronic pain. • Pain and atopic dermatitis share common inflammatory pathways. Inflammation, injury to the skin from scratching, fissures, and intolerance to irritants related to atopic dermatitis can cause pain. What is New: • Atopic dermatitis in early life is linked to an increased likelihood of experiencing pain at the age of 10, which suggests that exploring the potential for sensitization is a worthwhile area of investigation. • Our proof-of-concept study highlights the potential benefit of studying management targets and improving itching and relieving skin pain as quickly as possible, avoiding potential long-term consequences of the sensitization process.

Lactic Acid Bacteria isolated from traditional and innovative alheiras as potential biocontrol agents.

From a selection of seven traditional and 14 innovative alheiras, 491 lactic acid bacteria (LAB) were isolated and tested for their antimicrobial activity against several food-borne pathogens. Among these, six strains revealed antimicrobial activity through potential bacteriocin production against 14 Listeria monocytogenes strains, Enterococcus faecalis ATCC 29212, Clostridium sporogenes ESB050, and Clostridium perfringens ESB054. Through whole genome sequencing (WGS), these strains were identified as Lactiplantibacillus plantarum (2), Leuconostoc mesenteroides (1), and Pediococcus acidilactici (3). Furthermore, several orthologues of class II bacteriocins genes were identified, including Plantaricin E, Plantaricin F, Pediocin PA, Enterocin X, Leucocin A, and Coagulin A. No virulence or antibiotic resistance genes' orthologues were detected by WGS analysis. However, the selected LAB strains showed variable phenotypic patterns related to virulence genes and antibiotic resistance when assessed through classical methodologies. None of these strains demonstrated the production of biogenic amines, gelatinase or DNase. Additionally, no hemolytic activity or lipase enzyme production was observed. However, only Lpb. plantarum 9A3 was sensitive to all tested antibiotics and was thus chosen for further examination. The bacteriocins produced by Lpb. plantarum (9A3) exhibited stability across a broad range of conditions, including temperatures from 4 to 100 °C, pH values ranging from 2 to 8, exposure to surfactants and detergents (Tween 20 and 80, SDS, EDTA 0.1, 2 and 5 mM, urea and sodium deoxycholate), and enzymes (papain and catalase). Their maximum activity (AU/mL = 12,800) against four L. monocytogenes strains was observed between 21 and 36 h of growth of Lbp. plantarum 9A3, indicating a bacteriostatic mode of action. Therefore, this strain appears to be a robust candidate for potential application as a protective strain to be used in the food industry. Not only is it safe, but it also produces stable bacteriocins (harbouring genes encoding for the production of three) effectively inhibiting significant pathogens such as L. monocytogenes and C. perfringens.

Effectiveness of a home-based pulmonary rehabilitation maintenance programme: the Rehab2Life study protocol.

Pulmonary rehabilitation (PR) is the bedrock of non-pharmacological treatment for people with COPD. Nonetheless, it is well described in the literature that unless the patient changes his behaviour, the benefits of PR programmes will decline in six to twelve months after finishing the programme. Therefore, maintenance programmes can address the problem of PR programmes' effect loss over time.Community care units can provide multidisciplinary care in the current Portuguese primary health care context. These units have an interdisciplinary team that aims to develop competencies in COPD patients to self-manage the disease.This study aims to test the effectiveness of a 12-month home-based PR programme (Rehab2Life) compared to usual care through a single-blind randomised controlled trial with two parallel groups. The Rehab2Life programme includes two distinct phases. The first is an 8-week PR programme delivered to both groups, and the second is a PR maintenance programme delivered to the intervention group after the initial eight weeks. The control group receive the usual care and regular appointments. The primary outcome is functional capacity, and secondary outcomes are dyspnea, Health-Related Quality of Life (HRQoL), number of exacerbations, symptoms burden, anxiety and depression symptoms, and physical activity.We expect to observe that the home-based PR programme brings clinically relevant benefits to the participants at the end of the first eight weeks and that, at 12 months after the maintenance phase of the programme, benefits are less dissipated than in the control group. We expect to identify the characteristics of the patients who benefit the most from home-based programmes.The trial was registered on 7 April 2022 at ClinicalTrials.gov (NCT05315505).

Should India Move toward Vehicle Electrification? Assessing Life-Cycle Greenhouse Gas and Criteria Air Pollutant Emissions of Alternative and Conventional Fuel Vehicles in India.

We perform a state-specific life-cycle assessment of greenhouse gases (GHG) (CO2eq) and sulfur dioxide (SO2) emissions in India for representative passenger vehicles (two-wheelers, three-wheelers, four-wheelers, and buses) and technologies (internal combustion engine, battery electric, hybrid electric, and plug-in hybrid electric vehicles). We find that in most states, four-wheeler battery-electric vehicles (BEVs) have higher GHG and SO2 emissions than other conventional or alternative vehicles. Electrification of those vehicle classes under present conditions would not lead to emission reductions. Electrified buses and three-wheelers are the best strategies to reduce GHG emissions in many states, but they are also the worst strategy in terms of SO2 emissions. Electrified two-wheelers have lower SO2 emissions than gasoline in one state. The Indian grid would need to decrease its carbon dioxide emissions by 38-52% and SO2 emissions by 58-97% (depending on the state) for widespread vehicle electrification for sustainability purposes to make sense. If the 2030 goals for India under the Glasgow COP are met, we find that four-wheeler BEVs still have higher GHG emissions in 18 states compared to a conventional gasoline compact four wheeler, and all states will have higher SO2 emissions for BEVs across all vehicle types compared to their conventional counterparts.

Current and Future Estimates of Marginal Emission Factors for Indian Power Generation.

Emission factors from Indian electricity remain poorly characterized, despite known spatial and temporal variability. Limited publicly available emissions and generation data at sufficient detail make it difficult to understand the consequences of emissions to climate change and air pollution, potentially missing cost-effective policy designs for the world's third largest power grid. We use reduced-form and full-form power dispatch models to quantify current (2017-2018) and future (2030-2031) marginal CO2, SO2, NOX, and PM2.5 emission factors from Indian power generation. These marginal emissions represent emissions changes due to small changes in demand. For 2017-2018, spatial variability in marginal CO2 emission factors range 3 orders of magnitude across India's states. There is limited seasonal and intraday variability with coal generation likely to meet changes in demand more than half the time in more than half of the states. Assuming the Government of India approximate 2030 targets, the median marginal CO2 emission factor across states decreases by approximately a factor of 2, but emission factors still span 3 orders of magnitude across states. Under 2030-2031 assumptions there is greater seasonal and intraday variability by up to factors of two and four, respectively. Estimates provide emission factors to evaluate interventions such as electric vehicles, increased air conditioning, and energy efficiency.

Potentially unrecognised pain in children: Population-based birth cohort study at 7 years of age.

AIM: To estimate agreement in the point prevalence of any pain, high-intensity pain and pain in two or more sites according to parental and child report. METHODS: We conducted a prospective study of 5639 children from a Portuguese birth cohort - Generation XXI, where parents and 7-year-old children answered the same questions at the same time. We assessed the accuracy of parental report, considering children's self-report as the gold standard. RESULTS: At 7 years of age, 499 children (8.8% (95% confidence interval (CI) 8.1-9.6)) reported having pain at the time of the interview. Of those, 44.1% had high-intensity pain (3.9% (95% CI 3.4-4.4) of the whole sample) and 12.4% reported pain in two or more sites (1.1% (95% CI 0.8-1.4) of the whole sample). In this community setting, pain prevalence and intensity were lower when collected from parents. Parental report had sensitivity below 20% and specificity above 95% but its positive predictive value was at most 25%. CONCLUSION: Our findings support that, outside acute care, parents have a specific but not sensitive report of children's pain at the age of 7 years. Their report seemed useful to exclude major complaints but limited to screen children's pain. This limitation was higher for more severe pain, that is two or more sites or high-intensity pain. Children should be asked directly about pain to avoid under-estimating paediatric pain.

Fine particulate matter damages and value added in the US economy.

Emissions of most pollutants that result in fine particulate matter (PM2.5) formation have been decreasing in the United States. However, this trend has not been uniform across all sectors or regions of the economy. We use integrated assessment models (IAMs) to compute marginal damages for PM2.5-related emissions for each county in the contiguous United States and match location-specific emissions with these marginal damages to compute economy-wide gross external damage (GED) due to premature mortality. We note 4 key findings: First, economy-wide, GED has decreased by more than 20% from 2008 to 2014. Second, while much of the air pollution policies have focused to date on the electricity sector, damages from farms are now larger than those from utilities. Indeed, farms have become the largest contributor to air pollution damages from PM2.5-related emissions. Third, 4 sectors, comprising less than 20% of the national gross domestic product (GDP), are responsible for ∼75% of GED attributable to economic activities. Fourth, uncertainty in GED estimates tends to be high for sectors with predominantly ground-level emissions because these emissions are usually estimated and not measured. These findings suggest that policymakers should target further emissions reductions from such sectors, particularly in transportation and agriculture.

Expert assessments of the cost and expected future performance of proton exchange membrane fuel cells for vehicles.

Despite decades of development, proton exchange membrane fuel cells (PEMFCs) still lack wide market acceptance in vehicles. To understand the expected trajectories of PEMFC attributes that influence adoption, we conducted an expert elicitation assessment of the current and expected future cost and performance of automotive PEMFCs. We elicited 39 experts' assessments of PEMFC system cost, stack durability, and stack power density under a hypothetical, large-scale production scenario. Experts assessed the median 2017 automotive cost to be $75/kW, stack durability to be 4,000 hours, and stack power density to be 2.5 kW/L. However, experts ranged widely in their assessments. Experts' 2017 best cost assessments ranged from $40 to $500/kW, durability assessments ranged from 1,200 to 12,000 hours, and power density assessments ranged from 0.5 to 4 kW/L. Most respondents expected the 2020 cost to fall short of the 2020 target of the US Department of Energy (DOE). However, most respondents anticipated that the DOE's ultimate target of $30/kW would be met by 2050 and a power density of 3 kW/L would be achieved by 2035. Fifteen experts thought that the DOE's ultimate durability target of 8,000 hours would be met by 2050. In general, experts identified high Pt group metal loading as the most significant barrier to reducing cost. Recommended research and development (R&D) funding was allocated to "catalysts and electrodes," followed in decreasing amount by "fuel cell performance and durability," "membranes and electrolytes," and "testing and technical assessment." Our results could be used to inform public and private R&D decisions and technology roadmaps.

Effects of Air Emission Externalities on Optimal Ridesourcing Fleet Electrification and Operations.

Ridesourcing services from transportation network companies, like Uber and Lyft, serve the fastest growing share of U.S. passenger travel demand.1 Ridesourcing vehicles' high use intensity is economically attractive for electric vehicles, which typically have lower operating costs and higher capital costs than conventional vehicles. We optimize fleet composition (mix of conventional vehicles (CVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs)) and operations to satisfy demand at minimum cost and compare findings across a wide range of present-day and future scenarios for three cities. In nearly all cases, the optimal fleet includes a mix of technologies, HEVs and BEVs make up the majority of distance traveled, and CVs are used primarily for periods of peak demand (if at all). When life cycle air pollution and greenhouse gas emission externalities are internalized via a Pigovian tax, fleet electrification increases and externalities decrease, suggesting a role for policy. Externality reductions vary from 10% in New York (where externality costs for both gasoline and electricity consumption are relatively high and a Pigovian tax induces a partial shift to BEVs), to 22% in Los Angeles (where high gasoline and low electric grid externalities lead a Pigovian tax to induce a near-complete shift to BEVs).

Hydrogen Storage for Fuel Cell Electric Vehicles: Expert Elicitation and a Levelized Cost of Driving Model.

A cost-effective and compact hydrogen storage system could advance fuel cell electric vehicles (FCEVs). Today's commercial FCEVs incorporate storage that is projected to be heavier, larger, and costlier than targets set by the U.S. Driving Research and Innovation for Vehicle efficiency and Energy sustainability Partnership (U.S. DRIVE). To inform research and development (R&D), we elicited 31 experts' assessments of expected future costs and capacities of storage systems. Experts suggested that systems would approach U.S. DRIVE's ultimate capacity targets but fall short of cost targets at a high production volume. The 2035 and 2050 median costs anticipated by experts were $13.5 and $10.53/kWhH2, gravimetric capacities of 5.2 and 5.6 wt %, and volumetric capacities of 0.93 and 1.33 kWhH2/L, respectively. To meet U.S. DRIVE's targets, experts recommended allocating the majority of government hydrogen storage R&D funding to materials development. Furthermore, we incorporated experts' cost assessments into a levelized cost of driving model. Given technical and fuel price uncertainty, FCEV costs ranged from $0.38 to $0.45/mile ($0.24-$0.28/km) in 2020, $0.30 to $0.33/mile ($0.19-$0.21/km) in 2035-2050, and $0.27 to $0.31/mile ($0.17-$0.19/km) in 2050. Depending on fuel, electricity, and battery prices, our findings suggest that FCEVs could compete with conventional and alternative fuel vehicles by 2035.

Lung Auscultation Using the Smartphone-Feasibility Study in Real-World Clinical Practice.

Conventional lung auscultation is essential in the management of respiratory diseases. However, detecting adventitious sounds outside medical facilities remains challenging. We assessed the feasibility of lung auscultation using the smartphone built-in microphone in real-world clinical practice. We recruited 134 patients (median[interquartile range] 16[11-22.25]y; 54% male; 31% cystic fibrosis, 29% other respiratory diseases, 28% asthma; 12% no respiratory diseases) at the Pediatrics and Pulmonology departments of a tertiary hospital. First, clinicians performed conventional auscultation with analog stethoscopes at 4 locations (trachea, right anterior chest, right and left lung bases), and documented any adventitious sounds. Then, smartphone auscultation was recorded twice in the same four locations. The recordings (n = 1060) were classified by two annotators. Seventy-three percent of recordings had quality (obtained in 92% of the participants), with the quality proportion being higher at the trachea (82%) and in the children's group (75%). Adventitious sounds were present in only 35% of the participants and 14% of the recordings, which may have contributed to the fair agreement between conventional and smartphone auscultation (85%; k = 0.35(95% CI 0.26-0.44)). Our results show that smartphone auscultation was feasible, but further investigation is required to improve its agreement with conventional auscultation.

Ambulatory chest physiotherapy in mild-to-moderate acute bronchiolitis in children under two years of age - A randomized control trial.

OBJECTIVE: The aim of this study was to compare the role of a chest physiotherapy (CP) intervention to no intervention on the respiratory status of children under two years of age, with mild-to-moderate bronchiolitis. METHODS: Out of 80 eligible children observed in the Emergency Room, 45 children completed the study with 28 randomized to the intervention group and 17 to the control group. The intervention protocol, applied in an ambulatory setting, consisted of combined techniques of passive prolonged slow expiration, rhinopharyngeal clearance and provoked cough. The control group was assessed with no chest physiotherapy intervention. The efficacy of chest physiotherapy was assessed using the Kristjansson Respiratory Score at the admission and discharge of the visit to the Emergency Room and during clinical visits at day 7 and day 15. RESULTS: There was a significant improvement in the Kristjansson Respiratory Score in the intervention group compared to the control group at day 15 [1.2 (1.5) versus 0.3 (0.5); p -value = 0 . 005 , in the control and intervention groups, respectively], with a mean difference (95% CI) of - 0 . 9 ( - 1 . 6 to - 0 . 3 ). CONCLUSION: Chest physiotherapy had a positive impact on the respiratory status of children with mild-to-moderate bronchiolitis. CLINICAL TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT04260919.

Climate and Health Benefits of Rapid Coal-to-Gas Fuel Switching in the U.S. Power Sector Offset Methane Leakage and Production Cost Increases.

In this paper, we ask whether rapidly displacing coal electricity generation with underutilized, existing natural gas capacity has net societal benefits or net costs when considering climate change, economics, and air pollution. We use a power plant dispatch model to quantify the effects of dispatching because of a tax on carbon or because of a tax on carbon, methane leakage, and air pollution. We explicitly model exhaust stack CO2 emissions, production costs, health damages caused by criteria air pollutants, and methane leakage from the natural gas infrastructure. We show that (1) the optimal coal-to-gas redispatch displaces 62-77% of coal energy, leaving some coal online, (2) the health benefits of redispatch are larger in magnitude than the climate benefits, (3) reducing methane leakage rates from 2.3 to 2.0% increases the net climate benefits of redispatch by $1.1B-$1.4B, (4) although internalizing methane leakage, climate damages, and health damages in the power plant dispatch maximizes the net benefits of redispatch, 75-87% of these benefits can be achieved using a carbon tax mechanism alone, and (5) when choosing an optimal carbon tax, focusing on climate at the exclusion of health-and vice-versa-provides less net benefit than looking at both issues jointly.

Optimizing Emissions Reductions from the U.S. Power Sector for Climate and Health Benefits.

Improved air quality and human health are often discussed as "co-benefits" of mitigating climate change, yet they are rarely considered when designing or implementing climate policies. We analyze the implications of integrating health and climate when determining the best locations for replacing power plants with new wind, solar, or natural gas to meet a CO2 reduction target in the United States. We employ a capacity expansion model with integrated assessment of climate and health damages, comparing portfolios optimized for benefits to climate alone or both health and climate. The model estimates county-level health damages and accounts for uncertainty by using a range of air quality models (AP3, EASIUR, and InMAP) and concentration-response functions (American Cancer Society and Harvard Six Cities). We find that reducing CO2 by 30% yields $21-68 billion in annual health benefits, with an additional $9-36 billion possible when co-optimizing for climate and health benefits. Additional benefits accrue from prioritizing emissions reductions in counties with high population exposure. Total health benefits equal or exceed climate benefits across a wide range of modeling assumptions. Our results demonstrate the value of considering health in climate policy design and the need for interstate cooperation to achieve additional health benefits equitably.

Spatially resolved air-water emissions tradeoffs improve regulatory impact analyses for electricity generation.

Coal-fired power plants (CFPPs) generate air, water, and solids emissions that impose substantial human health, environmental, and climate change (HEC) damages. This work demonstrates the importance of accounting for cross-media emissions tradeoffs, plant and regional emissions factors, and spatially variation in the marginal damages of air emissions when performing regulatory impact analyses for electric power generation. As a case study, we assess the benefits and costs of treating wet flue gas desulfurization (FGD) wastewater at US CFPPs using the two best available treatment technology options specified in the 2015 Effluent Limitation Guidelines (ELGs). We perform a life-cycle inventory of electricity and chemical inputs to FGD wastewater treatment processes and quantify the marginal HEC damages of associated air emissions. We combine these spatially resolved damage estimates with Environmental Protection Agency estimates of water quality benefits, fuel-switching benefits, and regulatory compliance costs. We estimate that the ELGs will impose average net costs of $3.01 per cubic meter for chemical precipitation and biological wastewater treatment and $11.26 per cubic meter for zero-liquid discharge wastewater treatment (expected cost-benefit ratios of 1.8 and 1.7, respectively), with damages concentrated in regions containing a high fraction of coal generation or a large chemical manufacturing industry. Findings of net cost for FGD wastewater treatment are robust to uncertainty in auxiliary power source, location of chemical manufacturing, and binding air emissions limits in noncompliant regions, among other variables. Future regulatory design will minimize compliance costs and HEC tradeoffs by regulating air, water, and solids emissions simultaneously and performing regulatory assessments that account for spatial variation in emissions impacts.

Comparison of Kristjansson Respiratory Score and Wang Respiratory Score in infants with bronchiolitis in a hospital emergency department.

OBJECTIVE: Several respiratory scores have been created to evaluate bronchiolitis' severity level, but it is still not clear which is the best score. The aim of this study is to compare the Wang Respiratory Score (WRS) and the Kristjansson Respiratory Score (KRS) in the setting of an emergency room. METHODS: We performed a prospective observational study with 60 infants with bronchiolitis admitted to a paediatric emergency department. For both scores, we assessed inter-rater reliability between two different health professionals (physician and physiotherapist), internal consistency, and correlation with SpO2 testing the intraclass-correlation coefficient (ICC), weighted kappa, Cronbach α coefficient and Spearman tests, respectively. RESULTS: The inter-rater reliability was higher in KRS (ICC 0.79) and the Cronbach α and weighted kappa had similar values in KRS versus WRS. The correlation between the KRS/WRS and SpO2 was poor/moderate upon admission and discharge for the first observer and the second observer. CONCLUSIONS: While the internal consistency was similar in both scores, inter-rater reliability of KRS was higher than WRS, which allows us to conclude that it would have more consistent results when used to assess bronchiolitis' level of severity by health personnel in a busy hospital emergency room.

Reduced-Order Dispatch Model for Simulating Marginal Emissions Factors for the United States Power Sector.

This study develops a reduced-order power plant dispatch model and uses it to simulate marginal emissions factors (MEFs) for the 2014-2017 United States (U.S.) electric grid at the North American Electric Reliability Corporation (NERC) regional level. MEFs help quantify the health, environmental, and climate change impacts caused by changes in marginal net electricity consumption, which could result, for example, from new technologies or policies. This study develops the model, validates it against historical data, and compares its simulated MEFs against historically derived regression-based MEFs. Our method accurately reproduces CO2, SO2, and NOx emissions for multiple U.S. NERC regions and years and enables us to analyze future scenarios that are absent from the historical data. Though historically derived regression-based MEFs are generally more accurate, our simulated MEFs provide a more nuanced picture of how clusters of low- or high-emitting power plants of similar production cost create large swings in MEFs throughout the day. Policymakers could use these dynamic MEFs to target demand-reduction strategies at high-emissions portions of the power plant merit order.

How Much Are We Saving after All? Characterizing the Effects of Commonly Varying Assumptions on Emissions and Damage Estimates in PJM.

In recent years, several methods have emerged to estimate the emissions and health, environmental, and climate change damages avoided by interventions such as energy efficiency, demand response, and the integration of renewables. However, differing assumptions employed in these analyses could yield contradicting recommendations regarding intervention implementation. We test the magnitude of the effect of using different key assumptions-average vs marginal emissions, year of calculation, temporal and regional scope, and inclusion of nonemitting generation-to estimate Mid-Atlantic region power pool (PJM) emissions and damage factors. We further highlight the importance of factor selection by evaluating three illustrative 2017 power system examples in PJM. We find that for a simple building lighting intervention, using average emissions factors incorporating nonemitting generation underestimates avoided damages by 45% compared to marginal factors. For PJM demand response, outdated marginal emissions factors from 2016 overestimate avoided damages by 25% compared to 2017 factors. Our assessment of PJM summer load further suggests that fossil-only average emissions factors overestimate damages by 63% compared to average factors incorporating nonemitting generation. We recommend that energy modelers carefully select appropriate emissions metrics when performing their analyses. Furthermore, since the U.S. electric grid is rapidly changing, we urge decision-makers to frequently update (and consider forecasting) grid emissions factors.

Trace Element Mass Flow Rates from U.S. Coal Fired Power Plants.

Trace elements (TEs) exit coal-fired power plants (CFPPs) via solid, liquid, and gaseous waste streams. Estimating the TE concentrations of these waste streams is essential to selecting pollution controls and estimating emission reduction benefits. This work introduces a generalizable mass balance model for estimating TE mass flow rates in CFPP waste streams and evaluates model accuracy for the U.S. coal fleet given current data constraints. We stochastically estimate, using a bootstrapping approach, the 2015 plant-level mass flow rates of Hg, Se, As, and Cl to solid, liquid, and gas phase waste streams by combining publicly available data for combusted coal TE concentrations with estimates of TE partitioning within installed air pollution control processes. When compared with measured and reported data on TE mass flow rates, this model generally overestimates masses by 30-50%, with larger errors for Hg. The partitioning estimates are consistent for Se, As, and Cl removal from flue gas, but tend to underestimate Hg removal. While our model is suitable for first-order estimates of TE mass flows, future work to improve model performance should focus on collecting and using new data on TE concentrations in the coal blend, where data quality is the weakest.