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Cristina L Archer - One of the best experts on this subject based on the ideXlab platform.
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Baseload electricity from wind via compressed air energy storage caes
Renewable & Sustainable Energy Reviews, 2012Co-Authors: James E Mason, Cristina L ArcherAbstract:This study investigates two methods of transforming intermittent wind electricity into firm Baseload capacity: (1) using electricity from natural gas combined-cycle (NGCC) power plants and (2) using electricity from compressed air energy storage (CAES) power plants. The two wind models are compared in terms of capital and electricity costs, CO2 emissions, and fuel consumption rates. The findings indicate that the combination of wind and NGCC power plants is the lowest-cost method of transforming wind electricity into firm Baseload capacity power supply at current natural gas prices (∼$6/GJ). However, the electricity supplied by wind and CAES power plants becomes economically competitive when the cost of natural gas for electric producers is $10.55/GJ or greater. In addition, the Wind-CAES system has the lowest CO2 emissions (93% and 71% lower than pulverized coal power plants and Wind-NGCC, respectively) and the lowest fuel consumption rates (9 and 4 times lower than pulverized coal power plants and Wind-NGCC, respectively). As such, the large-scale introduction of Wind-CAES systems in the U.S. appears to be the prudent long-term choice once natural gas price volatility, costs, and climate impacts are all considered.
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supplying Baseload power and reducing transmission requirements by interconnecting wind farms
Journal of Applied Meteorology and Climatology, 2007Co-Authors: Cristina L Archer, Mark Z JacobsonAbstract:Wind is the world’s fastest growing electric energy source. Because it is intermittent, though, wind is not used to supply Baseload electric power today. Interconnecting wind farms through the transmission grid is a simple and effective way of reducing deliverable wind power swings caused by wind intermittency. As more farms are interconnected in an array, wind speed correlation among sites decreases and so does the probability that all sites experience the same wind regime at the same time. The array consequently behaves more and more similarly to a single farm with steady wind speed and thus steady deliverable wind power. In this study, benefits of interconnecting wind farms were evaluated for 19 sites, located in the midwestern United States, with annual average wind speeds at 80 m above ground, the hub height of modern wind turbines, greater than 6.9 m s 1 (class 3 or greater). It was found that an average of 33% and a maximum of 47% of yearly averaged wind power from interconnected farms can be used as reliable, Baseload electric power. Equally significant, interconnecting multiple wind farms to a common point and then connecting that point to a far-away city can allow the long-distance portion of transmission capacity to be reduced, for example, by 20% with only a 1.6% loss of energy. Although most parameters, such as intermittency, improved less than linearly as the number of interconnected sites increased, no saturation of the benefits was found. Thus, the benefits of interconnection continue to increase with more and more interconnected sites.
Della Forster - One of the best experts on this subject based on the ideXlab platform.
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continuity of care by a primary midwife caseload midwifery increases women s satisfaction with antenatal intrapartum and postpartum care results from the cosmos randomised controlled trial
BMC Pregnancy and Childbirth, 2016Co-Authors: Helen L Mclachlan, Della Forster, Maryann Davey, Tanya Farrell, Touran Shafiei, Mary Anne Biro, Lisa Gold, Maggie Flood, Ulla WaldenstromAbstract:Continuity of care by a primary midwife during the antenatal, intrapartum and postpartum periods has been recommended in Australia and many hospitals have introduced a caseload midwifery model of care. The aim of this paper is to evaluate the effect of caseload midwifery on women’s satisfaction with care across the maternity continuum. Pregnant women at low risk of complications, booking for care at a tertiary hospital in Melbourne, Australia, were recruited to a randomised controlled trial between September 2007 and June 2010. Women were randomised to caseload midwifery or standard care. The caseload model included antenatal, intrapartum and postpartum care from a primary midwife with back-up provided by another known midwife when necessary. Women allocated to standard care received midwife-led care with varying levels of continuity, junior obstetric care, or community-based general practitioner care. Data for this paper were collected by background questionnaire prior to randomisation and a follow-up questionnaire sent at two months postpartum. The primary analysis was by intention to treat. A secondary analysis explored the effect of intrapartum continuity of carer on overall satisfaction rating. Two thousand, three hundred fourteen women were randomised: 1,156 to caseload care and 1,158 to standard care. The response rate to the two month survey was 88 % in the caseload group and 74 % in the standard care group. Compared with standard care, caseload care was associated with higher overall ratings of satisfaction with antenatal care (OR 3.35; 95 % CI 2.79, 4.03), intrapartum care (OR 2.14; 95 % CI 1.78, 2.57), hospital postpartum care (OR 1.56, 95 % CI 1.32, 1.85) and home-based postpartum care (OR 3.19; 95 % CI 2.64, 3.85). For women at low risk of medical complications, caseload midwifery increases women’s satisfaction with antenatal, intrapartum and postpartum care. Australian New Zealand Clinical Trials Registry ACTRN012607000073404 (registration complete 23rd January 2007).
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the effect of primary midwife led care on women s experience of childbirth results from the cosmos randomised controlled trial
British Journal of Obstetrics and Gynaecology, 2016Co-Authors: Helen L Mclachlan, Della Forster, Maryann Davey, Tanya Farrell, Margaret Flood, Touran Shafiei, Ulla WaldenstromAbstract:Objective To determine the effect of primary midwife-led care (‘caseload midwifery’) on women's experiences of childbirth. Design Randomised controlled trial. Setting Tertiary care women's hospital in Melbourne, Australia. Population A total of 2314 low-risk pregnant women. Methods Women randomised to caseload care received antenatal, intrapartum and postpartum care from a primary midwife, with some care provided by a ‘back-up’ midwife. Women in standard care received midwifery-led care with varying levels of continuity, junior obstetric care or community-based medical care. Main outcome measures The primary outcome of the study was caesarean section. This paper presents a secondary outcome, women's experience of childbirth. Women's views and experiences were sought using seven-point rating scales via postal questionnaires 2 months after the birth. Results A total of 2314 women were randomised between September 2007 and June 2010; 1156 to caseload and 1158 to standard care. Response rates to the follow-up questionnaire were 88 and 74%, respectively. Women in the caseload group were more positive about their overall birth experience than women in the standard care group (adjusted odds ratio 1.50, 95% CI 1.22–1.84). They also felt more in control during labour, were more proud of themselves, less anxious, and more likely to have a positive experience of pain. Conclusions Compared with standard maternity care, caseload midwifery may improve women's experiences of childbirth. Tweetable abstract Primary midwife-led care (‘caseload midwifery’) improves women's experiences of childbirth.
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comparing satisfaction and burnout between caseload and standard care midwives findings from two cross sectional surveys conducted in victoria australia
BMC Pregnancy and Childbirth, 2014Co-Authors: Michelle Newton, Helen L Mclachlan, Karen Willis, Della ForsterAbstract:Caseload midwifery reduces childbirth interventions and increases women’s satisfaction with care. It is therefore important to understand the impact of caseload midwifery on midwives working in and alongside the model. While some studies have reported higher satisfaction for caseload compared with standard care midwives, others have suggested a need to explore midwives’ work-life balance as well as potential for stress and burnout. This study explored midwives’ attitudes to their professional role, and also measured burnout in caseload midwives compared to standard care midwives at two sites in Victoria, Australia with newly introduced caseload midwifery models. All midwives providing maternity care at the study sites were sent questionnaires at the commencement of the caseload midwifery model and two years later. Data items included the Midwifery Process Questionnaire (MPQ) to examine midwives’ attitude to their professional role, the Copenhagen Burnout Inventory (CBI) to measure burnout, and questions about midwives’ views of caseload work. Data were pooled for the two sites and comparisons made between caseload and standard care midwives. The MPQ and CBI data were summarised as individual and group means. Twenty caseload midwives (88%) and 130 standard care midwives (41%) responded at baseline and 22 caseload midwives (95%) and 133 standard care midwives (45%) at two years. Caseload and standard care midwives were initially similar across all measures except client-related burnout, which was lower for caseload midwives (12.3 vs 22.4, p = 0.02). After two years, compared to midwives in standard care, caseload midwives had higher mean scores in professional satisfaction (1.08 vs 0.76, p = 0.01), professional support (1.06 vs 0.11, p <0.01) and client interaction (1.4 vs 0.09, p <0.01) and lower scores for personal burnout (35.7 vs 47.7, p < 0.01), work-related burnout (27.3 vs 42.7, p <0.01), and client-related burnout (11.3 vs 21.4, p < 0.01). Caseload midwifery was associated with lower burnout scores and higher professional satisfaction. Further research should focus on understanding the key features of the caseload model that are related to these outcomes to help build a picture of what is required to ensure the long-term sustainability of the model.
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effects of continuity of care by a primary midwife caseload midwifery on caesarean section rates in women of low obstetric risk the cosmos randomised controlled trial
British Journal of Obstetrics and Gynaecology, 2012Co-Authors: Helen L Mclachlan, Della Forster, Maryann Davey, Tanya Farrell, Mary Anne Biro, Lisa Gold, Maggie Flood, Leah L Albers, Jeremy Oats, Ulla WaldenstromAbstract:Objective To determine whether primary midwife care (caseload midwifery) decreases the caesarean section rate compared with standard maternity care. Design Randomised controlled trial. Setting Tertiary-care women’s hospital in Melbourne, Australia. Population A total of 2314 low-risk pregnant women. Methods Women randomised to caseload received antenatal, intrapartum and postpartum care from a primary midwife with some care by ‘back-up’ midwives. Women randomised to standard care received either midwifery or obstetric-trainee care with varying levels of continuity, or community-based general practitioner care. Main outcome measures Primary outcome: caesarean birth. Secondary outcomes included instrumental vaginal births, analgesia, perineal trauma, induction of labour, infant admission to special/neonatal intensive care, gestational age, Apgar scores and birthweight. Results In total 2314 women were randomised–1156 to caseload and 1158 to standard care. Women allocated to caseload were less likely to have a caesarean section (19.4% versus 24.9%; risk ratio [RR] 0.78; 95% CI 0.67–0.91; P = 0.001); more likely to have a spontaneous vaginal birth (63.0% versus 55.7%; RR 1.13; 95% CI 1.06–1.21; P < 0.001); less likely to have epidural analgesia (30.5% versus 34.6%; RR 0.88; 95% CI 0.79–0.996; P = 0.04) and less likely to have an episiotomy (23.1% versus 29.4%; RR 0.79; 95% CI 0.67–0.92; P = 0.003). Infants of women allocated to caseload were less likely to be admitted to special or neonatal intensive care (4.0% versus 6.4%; RR 0.63; 95% CI 0.44–0.90; P = 0.01). No infant outcomes favoured standard care.
F J Santosalamillos - One of the best experts on this subject based on the ideXlab platform.
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combining wind farms with concentrating solar plants to provide stable renewable power
Renewable Energy, 2015Co-Authors: F J Santosalamillos, D Pozovazquez, J A Ruizarias, L Von Bremen, J TovarpescadorAbstract:Abstract We evaluate the extent to which a combination of wind power and concentrating solar power (CSP) may lead to stable and even Baseload power by taking advantage of: 1) spatiotemporal balancing of solar and wind energy resources and 2) storage capabilities of CSP plants. A case study is conducted for the region of Andalusia in Spain. To this end, spatiotemporal variability of modeled CSP and wind capacity factors in a 3-km spatial resolution grid were analyzed based on principal component analysis (PCA) and canonical correlation analysis (CCA). Results reveal that renewable Baseload power can be obtained in the study region by locating wind farms and CSP plants using balancing patterns derived from CCA and PCA. In addition, the power fluctuation reduction attained from these patterns was substantially higher than those obtained by interconnecting randomly-located wind farms and CSP plants across the study region. Results were particularly meaningful for the winter season. Upon considering storage capability of the CSP plants, results proved better. The main difference was a higher firm capacity value associated with spring and summer seasons. For the other seasons, the contribution of thermal storage capabilities of the CSP plants to stable power proved less relevant.
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a methodology for evaluating the spatial variability of wind energy resources application to assess the potential contribution of wind energy to Baseload power
Renewable Energy, 2014Co-Authors: F J Santosalamillos, D Pozovazquez, J A Ruizarias, V Larafanego, J TovarpescadorAbstract:We propose a method for analyzing the potential contribution of wind energy resources to stable (Baseload) power within a region. The method uses principal component analysis (PCA) to analyze spatiotemporal balancing of wind energy resources and then assesses the optimal wind farm location to reduce wind power fluctuations. The ability of different reference wind turbines, alone or interconnected, to provide stable power is ultimately evaluated at selected locations. The method was tested in the southern Iberian Peninsula, including offshore areas. We used hourly wind energy estimates from the WRF mesoscale model at 3-km spatial resolution for the period 2008–2010. First, results show a valuable spatial balancing pattern between the wind energy resources in the northeast study region and Strait of Gibraltar area. The pattern was found to result from the interaction of mesoscale zonal flow with the complex topography of the region. Second, the results indicate that by taking advantage of the spatial balancing pattern, the optimal allocation and interconnection of wind farms across the region, can substantially reduce wind power fluctuations. This optimal allocation can in some cases generate stable power, thereby contributing to Baseload power.
Robert H Socolow - One of the best experts on this subject based on the ideXlab platform.
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Baseload wind energy modeling the competition between gas turbines and compressed air energy storage for supplemental generation
Energy Policy, 2007Co-Authors: Jeffery B Greenblatt, Samir Succar, David Denkenberger, Robert H Williams, Robert H SocolowAbstract:Abstract The economic viability of producing Baseload wind energy was explored using a cost-optimization model to simulate two competing systems: wind energy supplemented by simple- and combined cycle natural gas turbines (“wind+gas”), and wind energy supplemented by compressed air energy storage (“wind+CAES”). Pure combined cycle natural gas turbines (“gas”) were used as a proxy for conventional Baseload generation. Long-distance electric transmission was integral to the analysis. Given the future uncertainty in both natural gas price and greenhouse gas (GHG) emissions price, we introduced an effective fuel price, p NGeff , being the sum of the real natural gas price and the GHG price. Under the assumption of p NGeff =$5/GJ (lower heating value), 650 W/m 2 wind resource, 750 km transmission line, and a fixed 90% capacity factor, wind+CAES was the most expensive system at ¢6.0/kWh, and did not break even with the next most expensive wind+gas system until p NGeff =$9.0/GJ. However, under real market conditions, the system with the least dispatch cost (short-run marginal cost) is dispatched first, attaining the highest capacity factor and diminishing the capacity factors of competitors, raising their total cost. We estimate that the wind+CAES system, with a greenhouse gas (GHG) emission rate that is one-fourth of that for natural gas combined cycle plants and about one-tenth of that for pulverized coal plants, has the lowest dispatch cost of the alternatives considered (lower even than for coal power plants) above a GHG emissions price of $35/tC equiv. , with good prospects for realizing a higher capacity factor and a lower total cost of energy than all the competing technologies over a wide range of effective fuel costs. This ability to compete in economic dispatch greatly boosts the market penetration potential of wind energy and suggests a substantial growth opportunity for natural gas in providing Baseload power via wind+CAES, even at high natural gas prices.
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Baseload wind energy modeling the competition between gas turbines and compressed air energy storage for supplemental generation
Energy Policy, 2007Co-Authors: Jeffery B Greenblatt, Samir Succar, David Denkenberger, Robert H Williams, Robert H SocolowAbstract:Abstract The economic viability of producing Baseload wind energy was explored using a cost-optimization model to simulate two competing systems: wind energy supplemented by simple- and combined cycle natural gas turbines (“wind+gas”), and wind energy supplemented by compressed air energy storage (“wind+CAES”). Pure combined cycle natural gas turbines (“gas”) were used as a proxy for conventional Baseload generation. Long-distance electric transmission was integral to the analysis. Given the future uncertainty in both natural gas price and greenhouse gas (GHG) emissions price, we introduced an effective fuel price, p NGeff , being the sum of the real natural gas price and the GHG price. Under the assumption of p NGeff =$5/GJ (lower heating value), 650 W/m 2 wind resource, 750 km transmission line, and a fixed 90% capacity factor, wind+CAES was the most expensive system at ¢6.0/kWh, and did not break even with the next most expensive wind+gas system until p NGeff =$9.0/GJ. However, under real market conditions, the system with the least dispatch cost (short-run marginal cost) is dispatched first, attaining the highest capacity factor and diminishing the capacity factors of competitors, raising their total cost. We estimate that the wind+CAES system, with a greenhouse gas (GHG) emission rate that is one-fourth of that for natural gas combined cycle plants and about one-tenth of that for pulverized coal plants, has the lowest dispatch cost of the alternatives considered (lower even than for coal power plants) above a GHG emissions price of $35/tC equiv. , with good prospects for realizing a higher capacity factor and a lower total cost of energy than all the competing technologies over a wide range of effective fuel costs. This ability to compete in economic dispatch greatly boosts the market penetration potential of wind energy and suggests a substantial growth opportunity for natural gas in providing Baseload power via wind+CAES, even at high natural gas prices.
J Tovarpescador - One of the best experts on this subject based on the ideXlab platform.
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combining wind farms with concentrating solar plants to provide stable renewable power
Renewable Energy, 2015Co-Authors: F J Santosalamillos, D Pozovazquez, J A Ruizarias, L Von Bremen, J TovarpescadorAbstract:Abstract We evaluate the extent to which a combination of wind power and concentrating solar power (CSP) may lead to stable and even Baseload power by taking advantage of: 1) spatiotemporal balancing of solar and wind energy resources and 2) storage capabilities of CSP plants. A case study is conducted for the region of Andalusia in Spain. To this end, spatiotemporal variability of modeled CSP and wind capacity factors in a 3-km spatial resolution grid were analyzed based on principal component analysis (PCA) and canonical correlation analysis (CCA). Results reveal that renewable Baseload power can be obtained in the study region by locating wind farms and CSP plants using balancing patterns derived from CCA and PCA. In addition, the power fluctuation reduction attained from these patterns was substantially higher than those obtained by interconnecting randomly-located wind farms and CSP plants across the study region. Results were particularly meaningful for the winter season. Upon considering storage capability of the CSP plants, results proved better. The main difference was a higher firm capacity value associated with spring and summer seasons. For the other seasons, the contribution of thermal storage capabilities of the CSP plants to stable power proved less relevant.
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a methodology for evaluating the spatial variability of wind energy resources application to assess the potential contribution of wind energy to Baseload power
Renewable Energy, 2014Co-Authors: F J Santosalamillos, D Pozovazquez, J A Ruizarias, V Larafanego, J TovarpescadorAbstract:We propose a method for analyzing the potential contribution of wind energy resources to stable (Baseload) power within a region. The method uses principal component analysis (PCA) to analyze spatiotemporal balancing of wind energy resources and then assesses the optimal wind farm location to reduce wind power fluctuations. The ability of different reference wind turbines, alone or interconnected, to provide stable power is ultimately evaluated at selected locations. The method was tested in the southern Iberian Peninsula, including offshore areas. We used hourly wind energy estimates from the WRF mesoscale model at 3-km spatial resolution for the period 2008–2010. First, results show a valuable spatial balancing pattern between the wind energy resources in the northeast study region and Strait of Gibraltar area. The pattern was found to result from the interaction of mesoscale zonal flow with the complex topography of the region. Second, the results indicate that by taking advantage of the spatial balancing pattern, the optimal allocation and interconnection of wind farms across the region, can substantially reduce wind power fluctuations. This optimal allocation can in some cases generate stable power, thereby contributing to Baseload power.