scholarly journals Chivor’s Life Extension Project (CLEP): From Sediment Management to Development of a New Intake System

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2743 ◽  
Author(s):  
David A. del Río ◽  
Hugo Moffett ◽  
César Nieto-Londoño ◽  
Rafael E. Vásquez ◽  
Ana Escudero-Atehortúa
Keyword(s):  
Life Expectancy ◽  
Energy Supply ◽  
Management Strategies ◽  
Sediment Management ◽  
Life Extension ◽  
Hydropower Project ◽  
Intake System ◽  
Operational Costs ◽  
Generation Capacity ◽  
Current Operation

Sedimentation is an important issue that has been studied for the watershed of reservoirs, since it increases operational costs of hydropower installations, reduces the life expectancy, and compromises the generation capacity due to volume reduction. This work addresses the implementation of Chivor’s Life Extension Project (CLEP), developed in order to extend the life of La Esmeralda reservoir, which is used for power generation in Colombia. Sediment dynamics studies are first described and connected to the need of the AES Corporation to extend the life expectancy of the Chivor Hydropower Project. The geotechnical and hydraulic designs are described and the main considerations and tools for the execution of such a project are addressed. The construction of the new intake system was developed under favorable geomorphological, geological, and hydrogeological conditions, and the project is being developed without affecting the current operation. Such an innovative project is the first of its class in Colombia and goes from studies of sediment transport and sediment management strategies in the watershed to the design and construction of new intakes, in order to extend the life of an existing 1000-MW (6% of Colombia’s demand) powerplant for 50 more years, contributing to a sustainable energy supply for the future.

Extending Life Expectancy of La Esmeralda Reservoir: A Bet to Support Colombia’s Future Energy Demand

2020 ◽  
Author(s):  
David A. del Río ◽  
Hugo Moffett ◽  
César Nieto-Londoño ◽  
Rafael E. Vásquez ◽  
Ana Escudero-Atehortúa
Keyword(s):  
Life Expectancy ◽  
Energy Demand ◽  
Technological Development ◽  
Management Plan ◽  
Sediment Management ◽  
Point Of View ◽  
Hydropower Plant ◽  
Life Extension ◽  
Hydropower Generation ◽  
Growing Economy

Abstract This work addresses the strategy of AES Corporation (AES Chivor) in order to extend the life of La Esmeralda reservoir to support Colombia’s future energy demand. Chivor Hydropower Plant entered into service in 1978 and has a capacity of 1000 MW, 8 % of Colombia’s demand. It is first described how the Colombian electricity energy mix is composed. Then, La Esmeralda reservoir, which is used by Chivor for power generation, is described; sediment management plans and maintenance costs for equipment and infrastructure are addressed. Then, sediment dynamics studies that have been done in order to determine life expectancy of La Esmeralda reservoir are listed. Such studies have been used to execute the Chivor’s Life Extension Project, which considers the modification of intakes as the best option to extend the life of the reservoir for at least 50 years, among several alternatives that were evaluated by a panel of international experts. This represents a challenge from the engineering point of view, and the project will be shown as a successful example for a country with such dependence on hydropower generation. Modernizing existing infrastructure without affecting the operation, as in this case, is crucial to show how a sustainable sediment management plan and technological development are necessary to extend life of hydropower generation projects, and to help meeting energy demand in a sustainable way for countries such as Colombia with a growing economy.

An improved small sewage treatment plant for biological purification of wastewater

1994 ◽  
Vol 29 (12) ◽  
pp. 23-29 ◽  
Author(s):  
G. Voigtländer ◽  
E.-P. Kulle
Keyword(s):  
Energy Supply ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Septic Tank ◽  
Additional Energy ◽  
Anaerobic Reactor ◽  
Step Process ◽  
Operational Costs ◽  
Aerobic Reactor

The paper presents a small sewage treatment plant (package plant) operating without additional energy. Purification of sewage is achieved in a three-step process: sedimentation tank, anaerobic reactor and wastewater pond or aerobic reactor. The efficiency of the anaerobic reactor - in contrast to the efficiency of a common septic tank - is significantly increased by using fixed biomass systems. Further degradation of sewage compounds by adhering microorganisms occurs in pond or aerobic reactor. The bed for the aerobic biomass is made of a semipermeable plastic film and arranged in order to ensure simultaneous supply of oxygen. The three pilot plants are showing different results. The main aims of research i.e. lowering of operational costs, energy supply, minimizing of maintenance expenditure and cleaning work, reliability of degradation efficiency have been achieved so far for the anaerobic reactor.

scholarly journals Sharing With Patients the Uncertainties Regarding the Management of Dyspepsia

2021 ◽  
Vol 8 ◽  
Author(s):  
Jochanan Benbassat
Keyword(s):  
Gastric Cancer ◽  
Patient Satisfaction ◽  
High Risk ◽  
Life Expectancy ◽  
Early Diagnosis ◽  
Cancer Detection ◽  
Symptom Relief ◽  
Management Strategies ◽  
Detection Rates ◽  
Test And Treat

Background: The management of patients with dyspepsia is uncertain. Some authors advocate endoscopy for all; others restrict endoscopy only to patients at high risk of gastric cancer, namely to those above an age threshold, or with a family history, dysphagia, loss of weight, anemia, or a childhood in Asian countries. Still others recommend various combinations between test-and-treat for Helicobacter pylori, anti-secretory treatment, and/or endoscopy.Objective: To highlight the uncertainties in the choice between the various strategies and argue that these uncertainties should be shared with the patient.Method: An overview of reported life expectancy, patient satisfaction, gastric cancer detection rates, symptom relief, and cost effectiveness of the management strategies for dyspepsia.Main Findings: There are no randomized controlled trials of the effect of screening by endoscopy on mortality of patients with gastric cancer. Lower grades of evidence suggest that early diagnosis reduces this mortality. Analyses, which assume a survival benefit of early diagnosis, indicate that mass screening in countries of high incidence gastric cancer (> 10 cases per 100,000) and targeted screening of high-risk persons in countries of low-intermediate incidence (<10 cases per 100,000) is cost-effective at a willingness to pay of $20,000–50,000 per QALY. Prompt endoscopy appears to be best for patient satisfaction and gastric cancer detection, and test-and-treat for H pylori—for symptom relief and avoiding endoscopies.Conclusions: The gain in life expectancy is the main source of uncertainty in the choice between management strategies. This choice should be shared with the patients after explaining uncertainties and eliciting their preferences.

scholarly journals Influence of the Power Generation Capacity of the Structural Parameters of a Piezoelectric Bimorph

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Xiaochao Tian ◽  
Jinzhi Zhu ◽  
Zhicong Wang ◽  
Hu Wang ◽  
Yuze Sun ◽  
...  
Keyword(s):  
Power Generation ◽  
Integrated Circuits ◽  
Energy Supply ◽  
Output Voltage ◽  
Structural Parameters ◽  
Electronic Devices ◽  
Generation Effect ◽  
Modulus Ratio ◽  
Piezoelectric Vibrator ◽  
Generation Capacity

With the popularization of integrated circuits, MEMS, and portable electronic devices, chemical batteries have many disadvantages as the main energy supply method, such as large size, high quality, and limited energy supply life, requiring regular replacement, resulting in waste of materials, environmental pollution, and other issues. From the above reasons, energy harvesting technology plays an important role in improving the efficiency and life of electronic equipment. In order to explore the influence of the bimorph piezoelectric vibrator’s structural parameters on the power generation capacity, this paper establishes a cantilever beam rectangular bimorph piezoelectric vibrator power generation model, derives the mathematical expression of the bimorph piezoelectric vibrator power generation, and determines the parameter factors that affect the power generation effect. Using MATLAB simulation analysis to obtain the influence relationship curve of system output voltage and structural parameters, the experiment tests the influence law of output voltage and thickness ratio, width-to-length ratio, and Young’s modulus ratio; the test results are consistent with the theoretical analysis, verifying the theory and the correctness of the analysis. The results show that when the thickness ratio is 0.58 and the width-to-length ratio is 1, the power generation effect of the piezoelectric vibrator is the best to reach 14.5V; the power generation capacity of the transducer is inversely proportional to Young’s modulus ratio. This research provides a new idea for the popularization of integrated circuits, MEMS, and portable electronic devices.

scholarly journals Reducing the Operational Cost of Cloud Data Centers through Renewable Energy

Algorithms ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 145 ◽  
Author(s):  
Demetrio Laganà ◽  
Carlo Mastroianni ◽  
Michela Meo ◽  
Daniela Renga
Keyword(s):  
Renewable Energy ◽  
Data Centers ◽  
Virtual Machines ◽  
Renewable Energy Sources ◽  
Management Strategies ◽  
Production Performance ◽  
Load Management ◽  
Cloud Data ◽  
Operational Costs ◽  
Allocation Process

The success of cloud computing services has led to big computing infrastructures that are complex to manage and very costly to operate. In particular, power supply dominates the operational costs of big infrastructures, and several solutions have to be put in place to alleviate these operational costs and make the whole infrastructure more sustainable. In this paper, we investigate the case of a complex infrastructure composed of data centers (DCs) located in different geographical areas in which renewable energy generators are installed, co-located with the data centers, to reduce the amount of energy that must be purchased by the power grid. Since renewable energy generators are intermittent, the load management strategies of the infrastructure have to be adapted to the intermittent nature of the sources. In particular, we consider EcoMultiCloud , a load management strategy already proposed in the literature for multi-objective load management strategies, and we adapt it to the presence of renewable energy sources. Hence, cost reduction is achieved in the load allocation process, when virtual machines (VMs) are assigned to a data center of the considered infrastructure, by considering both energy cost variations and the presence of renewable energy production. Performance is analyzed for a specific infrastructure composed of four data centers. Results show that, despite being intermittent and highly variable, renewable energy can be effectively exploited in geographical data centers when a smart load allocation strategy is implemented. In addition, the results confirm that EcoMultiCloud is very flexible and is suited to the considered scenario.

Safety Implications of Bridging the Energy Supply/Demand Gap in Nigeria through Associated Natural Gas Utilization

2007 ◽  
Vol 18 (3-4) ◽  
pp. 363-372
Author(s):  
Funso A. Akeredolu ◽  
Jacob A. Sonibare
Keyword(s):  
Natural Gas ◽  
Energy Supply ◽  
Energy Demand ◽  
Electricity Generation ◽  
Safe Delivery ◽  
Associated Gas ◽  
Gas Utilization ◽  
Aging Infrastructure ◽  
Generation Capacity ◽  
Installed Capacity

There exists a wide energy supply/demand gap in Nigeria. The local generation of electricity meets only 31% of the demand of 10000 MW. By contrast, only 39.6% of the total installed capacity for electricity generation is achieved, owing to aging infrastructure, etc. The energy demand/supply pattern and infrastructure critically reviewed thus suggested the need to increase the electricity generation capacity. Furthermore, Nigeria flares 77% of her associated natural gas. Apart from the environmental penalties that flaring represents, in monetary terms, over the 110 years' life of Nigeria's gas reserves, a conservative estimate of the cost of the gas so-flared was $330 billion (based on $20/barrel average price of crude). It was safely inferred that the way forward in meeting the country's energy demand should include a strong element of gas utilization. In previous publications by this group, it was established that while domestic cooking could reduce the flared gas by about 5.4%, a cohesive policy on associated gas use for electricity generation could eliminate gas flaring. For domestic utilization of the associated gas, burner design and safety concerns were identified as the key challenges to overcome. The paper reports the effectiveness of odorizers in leakage detection/ prevention by the local consumers. It also discusses the issue of prevention of gas explosions. The previous cases of gas accidents were reviewed. The safety approaches proffered in the paper identified the relevant areas of research for safe delivery and consumption of natural gas in Nigeria.

3D hydro-morphodynamic models as support tools for obtaining sustainable sediment management strategies of reservoirs

2020 ◽  
Author(s):  
Kilian Mouris ◽  
Leon Saam ◽  
Felix Beckers ◽  
Silke Wieprecht ◽  
Stefan Haun
Keyword(s):  
Sediment Transport ◽  
Water Level ◽  
Management Strategies ◽  
Sediment Management ◽  
Transport Processes ◽  
Water Levels ◽  
Hydraulic Structures ◽  
Suspended Sediment Transport ◽  
Reservoir Sedimentation ◽  
Bottom Outlets

<p>Reservoir sedimentation reduces not only the available storage volume of reservoirs, but may also create other serious problems, such as an increase of bed levels or accumulations of nutrients and contaminants, which affect the environment. An increase in bed levels at the head of the reservoir can reduce flood safety and increase the risk for the surrounding areas. Deposited sediments close to the dam may block hydraulic structures, such as the bottom outlets, or, in case they enter the intake, lead to possible abrasion of plant components (e.g. wear of turbines and pipes).</p><p>Prior to reservoir construction, a pre-evaluation of the sediment yield from the catchment is usually performed by using soil erosion and sediment delivery models. However, the trapping efficiency is often only obtained by empirical approaches, such as Brune’s or Churchill’s curve, which are based on the capacity of the reservoir and the mean annual inflow. This is still common practice, although 3D hydro-morphodynamic models became powerful tools to numerically study sediment transport and reservoir sedimentation prior to the construction of reservoirs as well as during its operation.</p><p>Within this study, a fully 3D hydro-morphodynamic numerical model, based on the Reynolds-averaged Navier-Stokes equations, is applied to a case study to simulate, on the one hand suspended sediment transport within a hydropower reservoir and on the other hand a reservoir flushing operation as potential management scenario, with the goal to remobilize already deposited sediments and to release these sediments from the reservoir. The modeled reservoir has a total storage capacity of around 14 million m³, whereby the water level can fluctuate due to pumped-storage operation by 40.5 m (difference between the maximum operation level and the operational outlet). At the head is the natural inflow of two creeks into the reservoir and a lateral transition tunnel is located on the orographic right side, which collects several headwater streams from adjacent catchments.</p><p>Simulations are performed for different operation modes of the reservoir. The results clearly show that through active reservoir management (variation of water levels as well as using the momentum of the discharge from the transition tunnel) the sediment motion in the reservoir can be affected to a certain extent. It is for instance possible to almost completely avoid reservoir sedimentation in front of the dam and the hydraulic structures (water intake and bottom outlets) during sediment-laden flows when simultaneously high discharges are provided from the laterally located transition tunnel. The conducted simulation results of reservoir flushing also show that the success of the flushing operation is strongly dependent on the water level. As expected, flushing with full drawdown of the water level is the most efficient method to release sediments.</p><p>Through the detailed results of the 3D hydro-morphodynamic model, it is feasible to receive a deeper knowledge of the ongoing sediment transport processes within the studied reservoir. The gained knowledge can further be used to derive sustainable and efficient management strategies for the sediment management of the reservoir.</p>

Potential causes of enhanced transfer of mercury to St. Lawrence River Biota: implications for sediment management strategies at Cornwall, Ontario, Canada

Hydrobiologia ◽  
2009 ◽  
Vol 647 (1) ◽  
pp. 81-98 ◽  
Author(s):  
J. J. Ridal ◽  
L. E. Yanch ◽  
A. R. Fowlie ◽  
N. R. Razavi ◽  
T. M. Delongchamp ◽  
...  
Keyword(s):  
Management Strategies ◽  
Sediment Management ◽  
St Lawrence River

scholarly journals Management of Active Surveillance-Eligible Prostate Cancer during Pretransplantation Workup of Patients with Kidney Failure: A Simulation Study

2020 ◽  
Vol 15 (6) ◽  
pp. 822-829 ◽  
Author(s):  
Uwe Bieri ◽  
Kerstin Hübel ◽  
Harald Seeger ◽  
Girish S. Kulkarni ◽  
Tullio Sulser ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Kidney Transplantation ◽  
Life Expectancy ◽  
Active Surveillance ◽  
Kidney Failure ◽  
Management Strategies ◽  
Interdisciplinary Treatment ◽  
Definitive Treatment ◽  
Waiting Period ◽  
Quality Adjusted Life

Background and objectivesThe general rule that every active malignancy is an absolute contraindication for kidney transplantation is challenged by kidney failure patients diagnosed with active surveillance-eligible prostate cancer during pretransplantation workup. Interdisciplinary treatment teams therefore often face the challenge of balancing the benefits of early kidney transplantation and the risk of metastatic progression. Hence, we compared the quality-adjusted life expectancy of different management strategies in kidney failure patients diagnosed with active surveillance-eligible prostate cancer during pretransplantation workup.Design, setting, participants, & measurementsA discrete event simulation model was developed on the basis of a systematic literature search, clinical guidelines, and expert opinion. After model validation and calibration, we simulated four management strategies in a hypothetical cohort of 100,000 patients: Definitive treatment (surgery or radiation therapy) and listing after a waiting period of 2 years, definitive treatment and immediate listing, active surveillance and listing after a waiting period of 2 years, and active surveillance and immediate listing. Individual patient results (quality-adjusted life years; QALYs) were aggregated into strategy-specific means (± SEs).ResultsActive surveillance and immediate listing yielded the highest amount of quality-adjusted life expectancy (6.97 ± 0.01 QALYs) followed by definitive treatment and immediate listing (6.75 ± 0.01 QALYs). These two strategies involving immediate listing not only outperformed those incorporating a waiting period of 2 years (definitive treatment: 6.32 ± 0.01 QALYs; active surveillance: 6.59 ± 0.01 QALYs) but also yielded a higher proportion of successfully performed transplantations (72% and 74% versus 56% and 59%), with less time on hemodialysis on average (4.02 and 3.81 years versus 4.80 and 4.65 years).ConclusionsAmong kidney failure patients diagnosed with active surveillance-eligible prostate cancer during pretransplantation workup, the active surveillance and immediate listing strategy outperformed the alternative management strategies from a quality of life expectancy perspective, followed by definitive treatment and immediate listing.

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