Energy return on investment (EROI) of solar PV: an attempt at reconciliation

In a recent Point of View piece, William Pickard made an excellent case for the importance of energy return on investment (EROI) as a useful metric for assessing longterm viability of energy-dependent systems from bands of hunter-gatherers, to modern society and, finally to the specific case of a solar electricity generating project. The author then highlighted a seeming disparity between a number of different research groups 1) Fthenakis group at Brookhaven, 2) Prieto group in Madrid, 3) Weißbach group in Berlin, and 4) Brandt group at Stanford all of whom have recently published values for the EROI (or similar metric) for solar photovoltaic (PV) technologies. Unfortunately, in so doing, the author directly compares results calculated using different system boundaries, methodologies, and assumptions. It is the purpose of this response to (1) adjust the results for the four groups to better compare like systems and (2) outline details of two methodological issues common in the EROI literature. The objective of these two activities is to explain much of the apparent disparity between the different EROI values produced by the different research groups

Key Factors Associated With Pulmonary Sequelae in the Follow-Up of Critically Ill COVID-19 Patients

Introduction: Critical COVID-19 survivors have a high risk of respiratory sequelae. Therefore, we aimed to identify key factors associated with altered lung function and CT scan abnormalities at a follow-up visit in a cohort of critical COVID-19 survivors. Methods: Multicenter ambispective observational study in 52 Spanish intensive care units. Up to 1327 PCR-confirmed critical COVID-19 patients had sociodemographic, anthropometric, comorbidity and lifestyle characteristics collected at hospital admission; clinical and biological parameters throughout hospital stay; and, lung function and CT scan at a follow-up visit. Results: The median [p25–p75] time from discharge to follow-up was 3.57 [2.77–4.92] months. Median age was 60 [53–67] years, 27.8% women. The mean (SD) percentage of predicted diffusing lung capacity for carbon monoxide (DLCO) at follow-up was 72.02 (18.33)% predicted, with 66% of patients having DLCO < 80% and 24% having DLCO < 60%. CT scan showed persistent pulmonary infiltrates, fibrotic lesions, and emphysema in 33%, 25% and 6% of patients, respectively. Key variables associated with DLCO < 60% were chronic lung disease (CLD) (OR: 1.86 (1.18–2.92)), duration of invasive mechanical ventilation (IMV) (OR: 1.56 (1.37–1.77)), age (OR [per-1-SD] (95%CI): 1.39 (1.18–1.63)), urea (OR: 1.16 (0.97–1.39)) and estimated glomerular filtration rate at ICU admission (OR: 0.88 (0.73–1.06)). Bacterial pneumonia (1.62 (1.11–2.35)) and duration of ventilation (NIMV (1.23 (1.06–1.42), IMV (1.21 (1.01–1.45)) and prone positioning (1.17 (0.98–1.39)) were associated with fibrotic lesions. Conclusion: Age and CLD, reflecting patients’ baseline vulnerability, and markers of COVID-19 severity, such as duration of IMV and renal failure, were key factors associated with impaired DLCO and CT abnormalities

Influence Of The Fabrication Process On The Corrosion Behavior Of Two High Entropy Alloys In Molten Solar Salt

Publisher Copyright: © European Powder Metallurgy Association (EPMA)High-entropy alloys are characterized by their high stability at elevated temperatures, making them a promising alloy family for extreme environments. One field where this characteristic is attractive is in concentrating solar-thermal power (CSP) technology, specifically in plants than employ molten salts (solar salt: 40% KNO3/60% NaNO3) as a thermal storage medium. This study examines the feasibility of using HEAs in components exposed to solar salt, including an original Co-free composition, FeCrMoAlTiNi, and another eutectic composition, AlFeCrCoNi. HEAs were produced using Arc Melting and Powder Metallurgy techniques. The latter processing route was chosen to achieve greater microstructural control, using rapid and ultra-rapid field-assisted sintering methods, such as thermomechanical sintering, Spark Plasma Sintering (SPS), and Electrical Resistance Sintering (ERS). The study results demonstrate improved corrosion resistance over the reference material and offer insights into the microstructural effects of processing routes and their possible relationship with behavior in the presence of molten salts.Peer reviewe

Disease Risk & Landscape Attributes of Tick-Borne Borrelia Pathogens in the San Francisco Bay Area, California

Habitat heterogeneity influences pathogen ecology by affecting vector abundance and the reservoir host communities. We investigated spatial patterns of disease risk for two human pathogens in the Borrelia genus–B. burgdorferi and B. miyamotoi–that are transmitted by the western black-legged tick, Ixodes pacificus. We collected ticks (349 nymphs, 273 adults) at 20 sites in the San Francisco Bay Area, California, USA. Tick abundance, pathogen prevalence and density of infected nymphs varied widely across sites and habitat type, though nymphal western black-legged ticks were more frequently found, and were more abundant in coast live oak forest and desert/semi-desert scrub (dominated by California sagebrush) habitats. We observed Borrelia infections in ticks at all sites where we able to collect >10 ticks. The recently recognized human pathogen, B. miyamotoi, was observed at a higher prevalence (13/349 nymphs = 3.7%, 95% CI = 2.0–6.3; 5/273 adults = 1.8%, 95% CI = 0.6–4.2) than recent studies from nearby locations (Alameda County, east of the San Francisco Bay), demonstrating that tick-borne disease risk and ecology can vary substantially at small geographic scales, with consequences for public health and disease diagnosis

Summary statistics of entomologic risk for <i>Ixodes pacificus</i> infected with <i>Borrelia</i> spp. in recreational areas of the San Francisco Bay Area.

<p>¹Betsy Crowder Trail is comprised of coast live oak woodland.</p><p>²Anniversary Trail is comprised of coastal scrub and moderate grassland.</p><p>³Meadow Trail is comprised of coast live oak woodland and Douglas fir forest.</p><p>Data are presented on density of nymphal (DON) <i>I</i>. <i>pacificus</i> (i.e., number of nymphs/100m² (calculated by (number of ticks collected/meters covered by transects) x100); density of infected nymphs (DIN) for <i>Borrelia</i> spp. (calculated by <i>Borrelia</i> prevalence x DON); and for <i>B</i>. <i>miyamotoi</i>, <i>B</i>. <i>burgdorferi</i> ss, and for <i>B</i>. <i>burgdorferi</i> sl.</p

Recreational areas in the San Francisco Bay area (left) sampled for western black-legged ticks, with a close-up (right) of recreational areas sampled in San Mateo and Santa Clara Counties.

<p>Recreational areas in the San Francisco Bay area (left) sampled for western black-legged ticks, with a close-up (right) of recreational areas sampled in San Mateo and Santa Clara Counties.</p

Study area showing independent variables: soil type (top left), elevation (top right), vegetation type (bottom left) and distance to roads (bottom right).

<p>Purple dots represent tick- drag transects in Santa Clara and San Mateo counties.</p

Prevalence data for <i>Borrelia</i> in <i>I</i>. <i>pacificus</i> ticks from previous studies in California.

<p>¹Number positive/number tested (percentage positive, 95% CI).</p><p>Prevalence data for <i>Borrelia</i> in <i>I</i>. <i>pacificus</i> ticks from previous studies in California.</p