The implications of the declining energy return on investment of oil production Murphy, David J.
Philosophical transactions - Royal Society. Mathematical, Physical and engineering sciences/Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences,
01/2014, Letnik:
372, Številka:
2006
Journal Article
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Declining production from conventional oil resources has initiated a global transition to unconventional oil, such as tar sands. Unconventional oil is generally harder to extract than conventional ...oil and is expected to have a (much) lower energy return on (energy) investment (EROI). Recently, there has been a surge in publications estimating the EROI of a number of different sources of oil, and others relating EROI to long-term economic growth, profitability and oil prices. The following points seem clear from a review of the literature: (i) the EROI of global oil production is roughly 17 and declining, while that for the USA is 11 and declining; (ii) the EROI of ultra-deep-water oil and oil sands is below 10; (iii) the relation between the EROI and the price of oil is inverse and exponential; (iv) as EROI declines below 10, a point is reached when the relation between EROI and price becomes highly nonlinear; and (v) the minimum oil price needed to increase the oil supply in the near term is at levels consistent with levels that have induced past economic recessions. From these points, I conclude that, as the EROI of the average barrel of oil declines, long-term economic growth will become harder to achieve and come at an increasingly higher financial, energetic and environmental cost.
Since the Pennsylvania oil rush of 1859, petroleum has quickly become the dominant fuel of industrial society. The “Peak Oil” debate focused on whether or not there was an impending production crunch ...of cheap oil, and whilst there have been no shortages across the globe, a shift from conventional to unconventional oil liquids has occurred. One aspect of this shift was not fully explored in previous discussions–although of some importance in a low-carbon energy transition context: the extent to which the net-energy supply of oil products is affected by the use of lower quality energy sources. To fill this gap, this paper incorporates standard EROI (energy-return-on-investment) estimates and dynamic decline functions in the GlobalShift all-liquids bottom-up model on a global scale. We determine the energy necessary for the production of oil liquids (including direct and indirect energy costs) to represent today 15.5% of the energy production of oil liquids, and growing at an exponential rate: by 2050, a proportion equivalent to half of the gross energy output will be engulfed in its own production. Our findings thus question the feasibility of a global and fast low-carbon energy transition. We therefore suggest an urgent return of the peak oil debate, but including net-energy issues and avoiding a narrow focus on ‘peak supply’ vs ‘peak demand’.
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•Global gross and net-energy of oil liquids production is determined from 1950 to 2050.•Energy required for production is estimated to be 15.5% of the actual gross energy.•Oil liquids become a limit to a rapid and global low-carbon energy transition.•The peak supply vs. peak demand dispute needs to be re-examined.•Focus should be put instead on net-energy transition and wise energy consumption.
Estimates from claims-based analyses suggest that the incidence of sepsis is increasing and mortality rates from sepsis are decreasing. However, estimates from claims data may lack clinical fidelity ...and can be affected by changing diagnosis and coding practices over time.
To estimate the US national incidence of sepsis and trends using detailed clinical data from the electronic health record (EHR) systems of diverse hospitals.
Retrospective cohort study of adult patients admitted to 409 academic, community, and federal hospitals from 2009-2014.
Sepsis was identified using clinical indicators of presumed infection and concurrent acute organ dysfunction, adapting Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3) criteria for objective and consistent EHR-based surveillance.
Sepsis incidence, outcomes, and trends from 2009-2014 were calculated using regression models and compared with claims-based estimates using International Classification of Diseases, Ninth Revision, Clinical Modification codes for severe sepsis or septic shock. Case-finding criteria were validated against Sepsis-3 criteria using medical record reviews.
A total of 173 690 sepsis cases (mean age, 66.5 SD, 15.5 y; 77 660 42.4% women) were identified using clinical criteria among 2 901 019 adults admitted to study hospitals in 2014 (6.0% incidence). Of these, 26 061 (15.0%) died in the hospital and 10 731 (6.2%) were discharged to hospice. From 2009-2014, sepsis incidence using clinical criteria was stable (+0.6% relative change/y 95% CI, -2.3% to 3.5%, P = .67) whereas incidence per claims increased (+10.3%/y 95% CI, 7.2% to 13.3%, P < .001). In-hospital mortality using clinical criteria declined (-3.3%/y 95% CI, -5.6% to -1.0%, P = .004), but there was no significant change in the combined outcome of death or discharge to hospice (-1.3%/y 95% CI, -3.2% to 0.6%, P = .19). In contrast, mortality using claims declined significantly (-7.0%/y 95% CI, -8.8% to -5.2%, P < .001), as did death or discharge to hospice (-4.5%/y 95% CI, -6.1% to -2.8%, P < .001). Clinical criteria were more sensitive in identifying sepsis than claims (69.7% 95% CI, 52.9% to 92.0% vs 32.3% 95% CI, 24.4% to 43.0%, P < .001), with comparable positive predictive value (70.4% 95% CI, 64.0% to 76.8% vs 75.2% 95% CI, 69.8% to 80.6%, P = .23).
In clinical data from 409 hospitals, sepsis was present in 6% of adult hospitalizations, and in contrast to claims-based analyses, neither the incidence of sepsis nor the combined outcome of death or discharge to hospice changed significantly between 2009-2014. The findings also suggest that EHR-based clinical data provide more objective estimates than claims-based data for sepsis surveillance.
•I analyze data from an RCT in Kenya to determine whether an alcohol remission intervention affected peer relationships and network structures.•Results show that two peers randomly assigned to the ...treatment increase their relationship strength compared to two peers in the control.•Two nearby same-gender treatment peers are 9 percentage points more likely to have an agricultural information link with their peer.•Treated individuals increase their closeness centrality in agricultural information networks by 0.38 standard deviations.•Study suggests indirect benefits on relationship outcomes and community social capital from substance abuse programs and self-help programs.
External shocks or stimuli can have significant effects on community network structures, which in turn can affect relationship ties and social capital. To this point, however, few studies analyze impacts of self-help programs, such as those targeting substance abuse, on network structures or measures of social capital. This study analyzes the effects of a randomized control trial (RCT) in western Kenya that included an intervention aimed at decreasing alcohol abuse using group therapies and spousal level counseling. Using dyadic network data collected from alcohol-using households, the analysis finds that two nearby same-gender peers randomly assigned to the treatment group are 9 percentage points pp more likely to have an agricultural information link with their peer and 8 pp more likely to work with their peer compared to two individuals in the control group. Additional individual-level results find that assignment to the treatment significantly increases an individual’s network centrality as measured by degree, closeness, and betweenness. I explore potential mechanisms and find evidence suggesting network effects at the intensive and extensive margin and the development of support linkages all likely contributed to these results. This study shows that programs utilizing peer effects can not only have positive impacts on alcohol consumption, but also positive spillover effects on relationship ties and on a treated individual’s network centrality. The results thus suggest significant positive impacts of the program on social capital, and points to the indirect benefits of substance abuse programs (and self-help programs in general) on communities.
This paper shows the causal relationship between mutual religious association and the formation of social ties. We analyze dyadic relationships and show that joint attendance at a religious ...institution (RI) increases the probability of sharing information with and trusting a peer. We use a novel spatial instrumental variable strategy that combines insights from homestead inheritance institutions with triangular distances between peers and RI locations within villages in Kenya. We find that shared attendance at an RI increases the likelihood of receiving advice from a peer by 30 percentage points, demonstrating the strong impact of weak ties formed through social spaces.
Natural gas is expected to play an important role in the coming low-carbon energy transition. However, conventional gas resources are gradually being replaced by unconventional ones and a question ...remains: to what extent is net-energy production impacted by the use of lower-quality energy sources? This aspect of the energy transition was only partially explored in previous discussions. To fill this gap, this paper incorporates standard energy-return-on-investment (EROI) estimates and dynamic functions into the GlobalShift bottom-up model at a global level. We find that the energy necessary to produce gas (including direct and indirect energy and material costs) corresponds to 6.7% of the gross energy produced at present, and is growing at an exponential rate: by 2050, it will reach 23.7%. Our results highlight the necessity of viewing the energy transition through the net-energy prism and call for a greater number of EROI studies.
Abstract
Mantis shrimp swim via metachronal rowing, a pattern in which the pleopods (swimming limbs) stroke sequentially, starting with the last pair and followed by anterior neighbors. A similar ...swimming pattern is used at various sizes, Reynolds numbers, and advance ratios by diverse organisms including ciliates, ctenophores, copepods, krill, and lobsters. Understanding this type of locomotion is important because it is widespread and may inspire the design of underwater vehicles where efficiency, robustness, and maneuverability are desired. However, detailed measurements of the flow around free-swimming, metachronally rowing organisms are scarce, especially for organisms swimming in a high Reynolds number regime (Re ≥ 104). In this study, we present time-resolved, planar PIV measurements of a swimming peacock mantis shrimp (Odontodactylus scyllarus). Simultaneous kinematics measurements of the animal, which had body and pleopod lengths of 114 and 20 mm, respectively, reveal mean swimming speeds of 0.2–1.9 m s−1 and pleopod beat frequencies of 3.6–13 Hz, corresponding to advance ratios of 0.75–1.84 and body-based Reynolds numbers of 23,000–217,000. Further, the animal’s stroke is not purely metachronal, with a long phase lag between initiation of the first and fifth pleopod power strokes. Flow measurements in the sagittal plane show that each stroking pleopod pair creates a posteriorly moving tip vortex which evades destruction by the recovery strokes of other pleopod pairs. The vortex created by the anteriormost pleopod pair is the strongest and, owing to the animal’s high advance ratio, is intercepted by the power stroke of the posteriormost pleopod pair. The vortex strength increases as a result of this interaction, which may increase swimming speed or efficiency. A relationship for vortex interception by the posterior pleopod is proposed that relates the phase lag between the interacting pleopods to the beat frequency, distance between those pleopods, and speed of the vortex relative to the animal. We describe this interaction with a novel parameter called the interpleopod vortex phase matching Strouhal number StIVPM which is equal to the phase lag between interacting pleopods. This new nondimensional parameter may be useful in predicting the conditions where a constructive interaction may occur in other species or in physical models. Finally, we relate the advance ratio to the Reynolds number ratio, the ratio between the body-based Reynolds number and the pleopod-based Reynolds number. The importance of these parameters in promoting the interpleopod vortex interactions identified here, in dynamically scaled experiments, and in wake signatures behind schooling metachronal swimmers is discussed.
To determine mortality rates among adults with critical illness from coronavirus disease 2019.
Observational cohort study of patients admitted from March 6, 2020, to April 17, 2020.
Six coronavirus ...disease 2019 designated ICUs at three hospitals within an academic health center network in Atlanta, Georgia, United States.
Adults greater than or equal to 18 years old with confirmed severe acute respiratory syndrome-CoV-2 disease who were admitted to an ICU during the study period.
None.
Among 217 critically ill patients, mortality for those who required mechanical ventilation was 35.7% (59/165), with 4.8% of patients (8/165) still on the ventilator at the time of this report. Overall mortality to date in this critically ill cohort is 30.9% (67/217) and 60.4% (131/217) patients have survived to hospital discharge. Mortality was significantly associated with older age, lower body mass index, chronic renal disease, higher Sequential Organ Failure Assessment score, lower PaO2/FIO2 ratio, higher D-dimer, higher C-reactive protein, and receipt of mechanical ventilation, vasopressors, renal replacement therapy, or vasodilator therapy.
Despite multiple reports of mortality rates exceeding 50% among critically ill adults with coronavirus disease 2019, particularly among those requiring mechanical ventilation, our early experience indicates that many patients survive their critical illness.
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