Journal Articles
Journal Articles
Socio-Technical Viability Framework for Micro Hydropower in Group Water-Energy Schemes
Adeyeye, K.; Gallagher, J.; McNabola, A.; Ramos, H.M.(2021). Coughlan, P. Socio-Technical Viability Framework for Micro Hydropower in Group Water-Energy Schemes. Energies, 14, 4222.
Abstract
Most renewable energy (RE) studies focus on technology readiness, environmental benefits and/or cost savings. The market permeation, viability and adoption of RE technologies such as micro hydropower (MHP), however, require the alignment of other interrelated factors, such as the socio-technical, institutional and political dimensions. This is particularly the case where the energy recovery potential in decentralised water networks is being explored as part of a wholesome sustainability strategy by and for individual and communal prosumers. This study employs a socio-technical approach to understand factors that influence the perceived viability and adoption of MHP in group water-energy schemes. Methods included a progressive literature review to formulate a conceptual framework for the implementation of MHP systems. The framework was validated using survey data from representative stakeholders from groups schemes in Ireland and Spain. These stakeholders were sampled and surveyed at the stage of considering the adoption of MHP in their water networks. The findings highlight the push–pull factors and discusses the opportunities and barriers to the adoption of MHP systems. It confirms that the market, institutional and policy context, cost and financial benefits, social support and collaborative services combine to influence the adoption of MHP technology. Thus, a framework for evaluating the socio-technical viability of MHP systems based on these more realistic integrated, multi-dimensional criteria is proposed.
Sustainable Water-Energy Nexus towards Developing Countries’ Water Sector Efficiency
Ramos, H.M.; Morillo, J.G.; Diaz, J.A.R.; Carravetta, A.; McNabola, (2021). A. Sustainable Water-Energy Nexus towards Developing Countries’ Water Sector Efficiency. Energies, 14, 3525.
Abstract
Water management and energy recovery can improve a system’s sustainability and efficiency in a cost-effective solution. This research assesses the renewable energy sources used in the water sector, as well as the related water sector performance indicators within Portuguese water management systems. A deep analysis of 432 water entities in Portugal, based on ERSAR data base, was conducted in order to identify factors to be improved regarding the system efficiency. On the other hand, the potential energy recovery developed in the REDAWN project was also used as a reference for the application of micro hydropower (MHP) solutions in the water sector. A water and energy nexus model was then developed to improve the systems efficiency and sustainability. A real case study in Africa, the Nampula water supply system, located in Mozambique, was selected as a promising potential for energy recovery. The application of a pump-as-turbine (PAT) allows the reduction in system costs and environmental impacts while increasing its efficiency. The proposed MHP has a capacity to generate ~23 MWh/year, providing significant savings. The developed economic analysis indicates the project is profitable, with an IRR ~40% depending on the energy selling price. This project can avoid the emission of more than 12 tCO2 to the atmosphere, and it can help to reduce the system’s real losses by more than 10,000 m3/year. Consequently, it creates a total economic benefit of 7604 EUR/year.
The environmental and economic benefits of a hybrid hydropower energy recovery and solar energy system (PAT-PV), under varying energy demands in the agricultural sector
Mérida García A, Gallagher J, Crespo Chacon A, McNabola A. (2021). The environmental and economic benefits of a hybrid hydropower energy recovery and solar energy system (PAT-PV), under varying energy demands in the agricultural sector. Journal of Cleaner Production. Vol 303, (2021) 127078.
Abstract
A comparative environmental and economic impact analysis between a hybrid pump-as-turbine/solarpilot system (PAT-PV) and a traditional diesel generator, with the innovation of the seasonal energysupply preconditions in an off-grid farm in Southern Spain was conducted. The results show lowerclimate change, fossil fuels, and dissipated water burdens over a 20-year lifespan, for the hybrid PAT-PVsystem, especially for fossil fuels (40-times lower). However, there was an increased demand for mineralsand metals compared with the diesel generator, mostly due to the batteries and electronic componentscontribution, representing between 66% and 87% of the burdens. The hybrid PAT-PV system presented alower total cost, but a higher investment, with an 8-year payback period. The low energy demand of thefarm represented only 2.2% of the energy potential generation of the hybrid PAT-PV system, with a higherimpact per kWh of energy than expected. The total use of the energy generated was proven to beessential, decreasing the environmental impacts up to 45 times, which provide a way to further reducefossil energy consumption at farm level, as surplus energy could be used to power electric vehicles ortools, contributing to the reduction of GHG emissions, for a more sustainable agriculture.
Multi-Country Scale Assessment of Available Energy Recovery Potential Using Micro-Hydropower in Drinking, Pressurised Irrigation and Wastewater Networks, Covering Part of the EU
Mitrovic D., Crespo Chacón M., Mérida García A., García Morillo J., Rodríguez Diaz JA., Ramos HM., Adeyeye K, Carravetta A., McNabola A. (2021). Multi‐Country Scale Assessment of Available Energy Recovery Potential Using Micro‐Hydropower in Drinking, Pressurised Irrigation and Wastewater Networks, Covering Part of the EU. In Water (Vol 13. No 7, 899).
Abstract
Studies have shown micro-hydropower (MHP) opportunities for energy recovery and CO2 reductions in the water sector. This paper conducts a large-scale assessment of this potential using a dataset amassed across six EU countries (Ireland, Northern Ireland, Scotland, Wales, Spain, and Portugal) for the drinking water, irrigation, and wastewater sectors. Extrapolating the collected data, the total annual MHP potential was estimated between 482.3 and 821.6 GWh, depending on the assumptions, divided among Ireland (15.5–32.2 GWh), Scotland (17.8–139.7 GWh), Northern Ireland (5.9–8.2 GWh), Wales (10.2–8.1 GWh), Spain (375.3–539.9 GWh), and Portugal (57.6–93.5 GWh) and distributed across the drinking water (43–67%), irrigation (51–30%), and wastewater (6–3%) sectors. The findings demonstrated reductions in energy consumption in water networks between 1.7 and 13.0%. Forty-five percent of the energy estimated from the analysed sites was associated with just 3% of their number, having a power output capacity >15 kW. This demonstrated that a significant proportion of energy could be exploited at a small number of sites, with a valuable contribution to net energy efficiency gains and CO2 emission reductions. This also demonstrates cost-effective, value-added, multi-country benefits to policy makers, establishing the case to incentivise MHP in water networks to help achieve the desired CO2 emissions reductions targets.
Optimization-Based Methodology for Selection of Pump-as-Turbine in Water Distribution Networks: Effects of Different Objectives and Machine Operation Limits on Best Efficiency Point
Mitrovic D, Garcia Morillo J, Rodriguez Diaz JA, McNabola A., Optimization-Based Methodology for Selection of Pump-as-Turbine in Water Distribution Networks: Effects of Different Objectives and Machine Operation Limits on Best Efficiency Point. (2021) Journal of Water Resources Planning and Management, (Vol. 147 Issue 5).
Abstract
In recent years, many researchers have recognized pressure reducing valves (PRVs) as potential microhydropower (MHP) sites, aiming to improve the efficiency of water networks. Pump-as-turbines (PATs) have been pointed out as the most suitable technology because of their favorable cost. Most of the methodologies available in the literature for selection of a PAT to replace a PRV follow a traditional approach that is based on scaling aprototype data using affinity curves, thus restricting the solution space only to these curves. The optimization-based methodology presented in this paper uses the classical hydraulic regulation scheme with the Nedler–Mead simplex direct search algorithm to search for the optimal solution within space that is constrained only by the boundaries of available centrifugal PATs on the market. The methodology also defines the PAT’s operation limits based on the PAT’s relative mechanical power. Improvements gained by using the novel methodology have been demonstrated on real-world case studies from Ireland and Italy that were previously used in the literature. The results of the considered sites also suggest that the maximal global plant’s efficiency is around 80% of the maximal efficiency of the theoretically optimal PAT. The paper also examines effects of different objective functions and different PATs’ operation limits on the selection of the optimal PAT.
Energy Recovery Potential in Industrial and Municipal Wastewater Networks Using Micro-Hydropower in Spain
Mérida García A, Rodríguez Díaz JA, García Morillo J, McNabola A. (2021) Energy Recovery Potential in Industrial and Municipal Wastewater Networks Using Micro-Hydropower in Spain. Water. 13(5),691.
Abstract
The use of micro-hydropower (MHP) for energy recovery in water distribution networks is becoming increasingly widespread. The incorporation of this technology, which offers low-cost solutions, allows for the reduction of greenhouse gas emissions linked to energy consumption. In this work, the MHP energy recovery potential in Spain from all available wastewater discharges, both municipal and private industrial, was assessed, based on discharge licenses. From a total of 16,778 licenses, less than 1% of the sites presented an MHP potential higher than 2 kW, with a total power potential between 3.31 and 3.54 MW. This total was distributed between industry, fish farms and municipal wastewater treatment plants following the proportion 51–54%, 14–13% and 35–33%, respectively. The total energy production estimated reached 29 GWh∙year−1, from which 80% corresponded to sites with power potential over 15 kW. Energy-related industries, not included in previous investigations, amounted to 45% of the total energy potential for Spain, a finding which could greatly influence MHP potential estimates across the world. The estimated energy production represented a potential CO2 emission savings of around 11 thousand tonnes, with a corresponding reduction between M€ 2.11 and M€ 4.24 in the total energy consumption in the country.
Evaluation of the design and performance of a micro hydropower plant in a pressurised irrigation network: Real world application at farm-level in Southern Spain
Crespo Chacon M., Rodríguez Díaz J A., García Morillo J., McNabola A. (2021). Evaluation of the design and performance of a micro hydropower plant in a pressurised irrigation network: Real world application at farm-level in Southern Spain. In Renewable Energy, (Vol 169, P 1106-1120).
Abstract
Agriculture is one of the most energy intensive activities within the European Union. The common absence of electric infrastructure in these rural settings has led to the need for in situ generation in many cases. The existing excess pressures in large pressurised irrigation networks makes the generation of micro hydropower here a possible alternative renewable energy source. Pump-as-turbines have been proposed as a cost-effective technology for such purposes, taking advantage of the excess pressure in pipe networks to produce energy. This paper presents a methodology for the design of a plant for micro hydropower generation in an agricultural farm and outlines the predicted benefits of the installation. These predicted benefits were also compared with the measured performance of the plant for the 2019 irrigation season. The main aim of the plant was to replace a diesel generator that supplied energy to the farm. The excess pressure found in the pipe network varied between 0m and almost 60m. The nominal power of the pump-as-turbine was selected to supply the maximum energy requirements of the farm. The predicted operation time of the plant was estimated at up to 3199 h concentrated between April and September. An annual savings of approximately €2950 and 11 t eCO2 were also estimated. The measured results showed an actual operation time of 2443 h between May and September, as in April the monitoring system was not operational. For this operation time, the savings were €2258 and 8.4 t eCO2. Considering the April theoretical irrigation time obtained, the savings raised up to approximately €2434 and 9.1 teCO2. The return on investment of the installation was computed to be recovered in less than ten years.
A New Preliminary Model to Optimize PATs Location in a Water Distribution Network
Morani, M. C., Carravetta, A., D’Ambrosio, C., & Fecarotta, O. (2020). A New Preliminary Model to Optimize PATs Location in a Water Distribution Network. In Environmental Sciences Proceedings (Vol. 2, No. 1, p. 57)
Abstract
Water distribution networks are low-energy efficiency systems, due to the high energy consumption, as well as the large amount of water leakage, which are caused by high pressures in the networks. In this study, the optimal location of pumps as turbines (PATs) within a water distribution network is investigated in order to maximize the production of energy and water savings, as well as minimize installation costs. A literature mathematical model has been employed as reference model and the weaknesses of this previous study have been overcome by new constraints. The main preliminary results of the new optimization procedure will be presented and compared with the literature results. According to the results, the new optimization ensures a good solution, in term of water and energy savings, with low investment cost and a fast return in investment.
Optimal Regulation of Variable Speed Pumps in Sewer Systems
Cimorelli, L., & Fecarotta, O. (2020). Optimal Regulation of Variable Speed Pumps in Sewer Systems. In Environmental Sciences Proceedings (Vol. 2, No. 1, p. 58).
Abstract
In this work, the optimal regulation of variable speed pump (VSP) was solved by means of two optimization algorithms: a mixed-integer optimizer based on the BONMIN (Basic Open-Source Nonlinear Mixed Integer Programming) package, and an original hybrid genetic algorithm (GA) called GA–Powell’s direction set method (PDSM), which employs a derivative free inner optimizer, that is, the Powell’s direction set method (PDSM). The obtained results show how the use of a strategy based on the optimal regulation of VSP allows to obtain huge energy cost savings. The analysis of the results shows that the regulation of the plant does not apparently follow a general rule.
A Performance Prediction Model for Pumps as Turbines (PATs)
Fontanella, S., Fecarotta, O., Molino, B., Cozzolino, L., & Della Morte, R. (2020). A Performance Prediction Model for Pumps as Turbines (PATs). Water, 12(4), 1175.
Abstract
In recent years, the interest towards the use of pumps operating as turbines (PATs) for the generation of electrical energy has increased, due to the low cost of implementation and maintenance. The main issue that inhibits a wider use of PATs is the lack of corresponding characteristic curves, because manufacturers usually provide only the pump-mode performance characteristics. In the PAT selection phase, the lack of turbine-mode characteristic curves forces users to expend expensive and time-consuming efforts in laboratory testing. In the technical literature, numerous methods are available for the prediction of PAT turbine-mode performance based on the pump-mode characteristics, but these models are usually calibrated making use of few devices. To overcome this limit, a performance database called Redawn is presented and the data collected are used to calibrate novel PAT performance models.
Zero-net energy management for the monitoring and control of dynamically-partitioned smart water systems.
Giudicianni, C., Herrera, M., di Nardo, A., Carravetta, A., Ramos, H. M., & Adeyeye, K. (2020). Zero-net energy management for the monitoring and control of dynamically-partitioned smart water systems. Journal of Cleaner Production, 119745.
Abstract
The optimal and sustainable management of water distribution systems still represent an arduous task. In many instances, especially in aging water net-works, pressure management is imperative for reducing breakages and leakages. Therefore, optimal District Metered Areas represent an effective solution to decreasing the overall energy input without performance compromise.
Within this context, this paper proposes a novel adaptive management framework for water distribution systems by reconfiguring the original network layout into (dynamic) district metered areas. It utilises a multiscale clustering algorithm to schedule district aggregation/desegregation, whilst delivering energy and supply management goals. The resulting framework was tested in a water utility network for the simultaneously production of energy during the day (by means of the installation of micro-hydropower systems) and for the reduction of water leakage during the night.
From computational viewpoint, this was found to significantly reduce the time and complexity during the clustering and the dividing phase. In addition, in this case, a recovered energy potential of 19 MWh per year and leakage reduction of up to 16% was found. The addition of pump-as-turbines was also found to reduce investment and maintenance costs, giving improved reliability to the monitoring stations. The financial analyses to define the optimal period in which to invest also showed the economic feasibility of the proposed solution, which assures, in the analysed case study, a positive annual net income in just five years.
This study demonstrates that the combined optimisation, energy recovery and creation of optimized multiple-task district stations lead to an efficient, resilient, sustainable, and low-cost management strategy for water distribution networks.
Estimating regional potential for micro-hydropower energy recovery in irrigation networks on a large geographical scale
Miguel Crespo Chacón, Juan Antonio Rodríguez Díaz, Jorge García Morillo, Aonghus McNabola, (2020); Estimating regional potential for micro-hydropower energy recovery in irrigation networks on a large geographical scale, Renewable Energy, Volume 155, 2020, pp 396-406.
Abstract
Micro-hydropower has been highlighted as a potential technology suitable for installation in irrigation networks to reduce system overpressures and to reduce the net energy consumption of the irrigation process. However, the full impact of this technology on a large regional scale is unknown.
Artificial Neural Networks and regression models were used in this research to predict the energy recovery potential for micro-hydropower in on-demand pressurised irrigation networks across a large spatial scale. Predictors of energy recovery potential across spatial unit areas included: Irrigated land surface area, irrigation crop water requirements, rainfall, evapotranspiration, and mean topographical slope. The model was used to predict the energy recovery potential across the 164,000 ha of the Spanish provinces of Seville and Cordoba in the absence of hydraulic models.
A total of 21.05 GWh was identified as the energy potential which could have been recovered using micro-hydropower during the 2018 irrigation season. This amount of energy would have potentially reduced the energy consumption of the irrigation process in this region by approximately 12.8%. A reduction in energy consumption in the agriculture sector of this magnitude could have significant impacts on food production and climate change.
The main novelty of this paper lies in the assessment of micro hydropower resources in operating irrigation networks on a large geographical scale, in areas where no information is available. It provides an approximation of the existing potential using computational methods.
Pulsating spiral Poiseuille flow
Manna, M. & Vacca, A. & Verzicco, R.. (2020). Pulsating spiral Poiseuille flow. Journal of Fluid Mechanics. 890. 10.1017/jfm.2020.125.
Abstract
Direct numerical simulation of the Navier–Stokes equations has been used to investigate the Taylor–Couette flow with an imposed pulsatile axial pressure gradient resulting in a spiral Poiseuille flow modulated by an oscillating forcing. Keeping the Reynolds and Taylor numbers constant, both the amplitude and frequency of the oscillating component are varied to span a small region of the phase space.
In the narrow-gap geometry considered in this study, the base flow (spiral Poiseuille flow) is in the turbulent regime whereas the oscillating component is laminar. It has been found that the effect of the oscillation is to induce a global flow laminarization provided the frequency is sufficiently small (at constant amplitude) or the amplitude is sufficiently large (at constant frequency).
The coupling between steady and oscillating components has been analysed with the help of long-time and phase-averaged statistics. The reverse transition mechanism has been associated to an anisotropic modification of the Reynolds stress tensor components, which has been shown to be caused by an alteration of the pressure–strain interaction.
Transient-Flow Induced Compressed Air Energy Storage (TI-CAES) System towards New Energy Concept.
Besharat, M.; Dadfar, A.; Viseu, M.T.; Brunone, B.; Ramos, H.M. Transient-Flow Induced Compressed Air Energy Storage (TI-CAES) System towards New Energy Concept. Water 2020, 12, 601.
Abstract
In recent years, interest has increased in new renewable energy solutions for climate change mitigation and increasing the efficiency and sustainability of water systems. Hydropower still has the biggest share due to its compatibility, reliability and flexibility.
This study presents one such technology recently examined at Instituto Superior Técnico based on a transient-flow induced compressed air energy storage (TI-CAES) system, which takes advantage of a compressed air vessel (CAV). The CAV can produce extra required pressure head, by compressing air, to be use for either hydropower generation using a water turbine in a gravity system or to be exploited in a pumping system. The results show a controlled behaviour of the system in storing the pressure surge as compressed air inside a vessel.
Considerable power values are achieved as well, while the input work is practically neglected. Higher power values are attained for bigger air volumes. The TI-CAES offers an efficient and flexible solution that can be exploited in exiting water systems without putting the system at risk. The induced transients in the compressed air allow a constant outflow discharge characteristic, making the energy storage available in the CAV to be used as a pump storage hydropower solution.
Improved Planning of Energy Recovery in Water Systems Using a New Analytic Approach to PAT Performance Curves.
Pérez-Sánchez, M.; Sánchez-Romero, F.J.; Ramos, H.M.; López-Jiménez, P.A. Improved Planning of Energy Recovery in Water Systems Using a New Analytic Approach to PAT Performance Curves. Water 2020, 12, 468.
Abstract
The use of pumps working as turbines (PATs) to improve the energy efficiency of water networks has been studied in the last years. This recovery system is justified due to a low investment contrasting with the capacity to take advantage in certain points with low and medium recoverable heads.
Analyses of water systems using simulation software and/or optimization algorithms need the characteristic curves (head and efficiency) of the machines, which should be known with minor error by the water managers. The knowledge of the best efficiency point (BEP) as a turbine is one of the major limitations when the user wants to choose PATs. In this sense, the present research defines new approach equations to estimate the BEP of the PAT, as well as to predict the characteristic curves, comparing the results with the rest of the published methods.
The comparison demonstrated that the new proposal reduced the error indexes, improved the R2 and increased the accuracy of the error ellipse using an experimental database of 181 different PATs.
Smart Water Management towards Future Water Sustainable Networks
Ramos, H.M.; McNabola, A.; López-Jiménez, P.A.; Pérez-Sánchez, M. Smart Water Management towards Future Water Sustainable Networks. Water 2020, 12, 58.
Abstract
Water management towards smart cities is an issue increasingly appreciated under financial and environmental sustainability focus in any water sector. The main objective of this research is to disclose the technological breakthroughs associated with water and energy use.
A methodology is proposed and applied in a case study to analyze the benefits to develop smart water grids, showing the advantages offered by the development of control measures. The case study showed the positive results, particularly savings of 57 GWh and 100 Mm3 in a period of twelve years when different measures from the common ones were developed for the monitoring and control of water losses in smart water management. These savings contributed to reducing the CO2 emissions to 47,385t CO2-eq.
Finally, in order to evaluate the financial effort and savings obtained in this reference systems (RS) network, the investment required in the monitoring and water losses control in a correlation model case (CMC) was estimated, and, as a consequence, the losses level presented a significant reduction towards sustainable values in the next nine years. Since the pressure control is one of the main issues for the reduction of leakage, an estimation of energy production for Portugal is also presented.
Energy Transfer from the Freshwater to the Wastewater Network Using a PAT-Equipped Turbopump
Morani, M.C.; Carravetta, A.; Fecarotta, O.; McNabola, A. Energy Transfer from the Freshwater to the Wastewater Network Using a PAT-Equipped Turbopump. Water 2020, 12, 38.
Abstract
A new strategy to increase the energy efficiency in a water network exists using turbo pumps, which are systems consisting of a pump and a turbine directly coupled on a same shaft. In a turbo pump, the pump is fed by a turbine that exploits a surplus head in a freshwater network in order to produce energy for one system (wastewater) and reduce the excess pressure in another (drinking water). A pump as turbine (PAT) may be preferred over a classic turbine here due to its lower cost. The result of such a coupling is a PAT–pump turbocharger (P&P).
In this research, the theoretical performance of a P&P plant is employed using data from a real water distribution network to exploit the excess pressure of a freshwater stream and to feed a pump conveying wastewater toward a treatment plant. Therefore, the P&P plant is a mixed PAT–pump turbocharger, operating with both fresh and wastewater. A new method to perform a preliminary geometric selection of the machines constituting the P&P plant has been developed. Furthermore, the plant operation has been described by means of a new mathematical model under different boundary conditions.
Moreover, the economic viability of the plant has been assessed by comparison with a conventional wastewater pumping system working in ON/OFF mode. Therefore, the net present value (NPV) of the investment has been evaluated in both situations for different time periods. According to the economical comparison, the PAT–pump turbocharger represents the most economically advantageous configuration, at least until the useful life of the plant. Such convenience amounts to 175% up to a time period equal to 20 years.
Zero-net energy management for the monitoring and control of dynamically-partitioned smart water systems.
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Giudicianni, C., Herrera, M., di Nardo, A., Carravetta, A., Ramos, H. M., & Adeyeye, K. (2020). Zero-net energy management for the monitoring and control of dynamically-partitioned smart water systems. Journal of Cleaner Production, 119745. Abstract The optimal and sustainable management of water distribution systems still represent an arduous task. In many instances, especially in aging water net-works, pressure management is imperative for reducing breakages and leakages. Therefore, optimal District Metered Areas represent an effective solution to decreasing the overall energy input without performance compromise. Within this context, this paper proposes a novel adaptive management framework for water distribution systems by reconfiguring the original network layout into (dynamic) district metered areas. It utilises a multiscale clustering algorithm to schedule district aggregation/desegregation, whilst delivering energy and supply management goals. The resulting framework was tested in a water utility network for the simultaneously production of energy during the day (by means of the installation of micro-hydropower systems) and for the reduction of water leakage during the night. From computational viewpoint, this was found to significantly reduce the time and complexity during the clustering and the dividing phase. In addition, in this case, a recovered energy potential of 19 MWh per year and leakage reduction of up to 16% was found. The addition of pump-as-turbines was also found to reduce investment and maintenance costs, giving improved reliability to the monitoring stations. The financial analyses to define the optimal period in which to invest also showed the economic feasibility of the proposed solution, which assures, in the analysed case study, a positive annual net income in just five years. This study demonstrates that the combined optimisation, energy recovery and creation of optimized multiple-task district stations lead to an efficient, resilient, sustainable, and low-cost management strategy for water distribution networks. |
Micro hydropower and the water-energy-food nexus
Stocks, C (2020); Micro hydropower and the water-energy-food nexus, NS Energy, January 2020.
Abstract
Researchers Miguel Crespo Chacón and Kemi Adeyeye explain how the European-funded REDAWN project has been developed to explore the water-energy-food nexus, and to investigate how micro hydropower could help improve energy efficiency in the water sector.
A life cycle assessment of the construction phase of eleven micro-hydropower installations in the UK
T. Ueda, E.S. Roberts, A. Norton, D. Styles, A.P. Williams, H.M. Ramos, J. Gallagher, (2019), A life cycle assessment of the construction phase of eleven micro-hydropower installations in the UK, Journal of Cleaner Production, Volume 218, 2019, Pages 1-9, ISSN 0959-6526
Abstract
The rapid deployment of renewable energy technologies continues, yet the environmental impacts associated with their construction is accepted without sustainable design considerations. This life cycle assessment study quantifies the embodied burdens in the construction phase of eleven microhydropower installations, ranging from 70-100 kW in size. The consumption of concrete and aggregates, metals and plastics influence each of the five impact categories assessment differently. In relation to global warming potential, upstream production of concrete and aggregates contributed 25-44%, whilst production of plastics contributed 27-49%. For acidification potential, production of metals and plastics contributed 29-67% and 19-45%, respectively. Production of metals used in MHP projects contributed 86-98% of human toxicity potential and 79-98% of abiotic resource depletion, whilst production of plastics contributed 56-77% of fossil resource depletion potential. One low-head scheme had the highest global warming, acidification and fossil resource depletion burdens due to large quantities of materials used in construction, while another scheme demonstrated high human toxicity and abiotic resource depletion burdens due to a 3-km grid connection upgrade for exporting electricity. The results were more sensitive to the quantity of materials used in the micro-hydropower projects than to changes in transport and construction contributions. The use of alternative materials could reduce global warming potential, e.g. a wood-frame powerhouse instead of concrete construction would reduce it by 6-12%. The results also indicated a general trend of reduced burdens per kWh electricity generated as capacity increased. However, no clear correlations were found between site-specific characteristics and environmental impacts in constructing these micro-hydropower projects. Therefore, independent life cycle assessment case studies are still required to inform better construction practices for specific renewable energy projects, with significant potential to improve environmental performance, especially in relation to resource efficiency as per circular economy principles.
Sustainable water-energy nexus in the optimization of the BBC golf-course using renewable energies
Helena M. Ramos, M. Zilhao, P. Amparo López-Jiménez & Modesto Pérez Sánchez (2019) Sustainable water-energy nexus in the optimization of the BBC golf-course using renewable energies, Urban Water Journal, 16:3, 215-224
Abstract
Water distribution networks and irrigation systems consume high energy quantities that need to be recovered if the water managers want to meet sustainable systems. A sustainability optimization is proposed in this research in order to replace the energy consumption in a golf-course system by renewable solutions joining energy recovery, sustainable urban drainage systems and hybrid solutions (solar panels and wind turbine). Different sustainable approaches were considered in which energy (using PATs), economic and environmental factors were analysed. Both scenarios and analyses showed interesting values related to economic indicators and environmental reductions of CO2 emissions. The possibility to supply the daily electric consumption in the pumping stations was checked using only renewable systems. Net present value was calculated in different solutions, obtaining positive values as well as the payback period was lower than 6 years. The CO2 emissions were reduced from 257,000 to 11,500 kgCO2/year in the most unfavourable scenario.
Hydropower energy recovery in irrigation networks: Validation of a methodology for flow prediction and pump as turbine selection
Miguel Crespo Chacón, Juan Antonio Rodríguez Díaz, Jorge García Morillo, Aonghus McNabola, Hydropower energy recovery in irrigation networks: Validation of a methodology for flow prediction and pump as turbine selection, Renewable Energy, Volume 147, Part 1, 2020, Pages 1728-1738, ISSN 0960-1481
Abstract
In recent years, pump-as-turbines (PATs) have been highlighted for their potential benefits as an application of micro-hydropower (MHP) in water distribution networks. However, PATs come with disadvantages of relatively low peak efficiencies, which can be reduced further with large flow fluctuations. MHP and PATs in particular applied in irrigation networks is a relatively new area of research focus for these devices, and one that poses significant opportunities for energy saving as well as significant challenges due to variations in flow rate.
This paper discusses the validation of a statistical methodology to estimate the flow and head variability in a network, and to select PATs whose best efficiency point (BEP) returns the lowest payback period. A comparison between the predicted and actual occurrence probabilities for different flow rates was carried out at nine potential points for MHP installation identified within a real network in Southwestern Spain.
For the flow occurrence probability, the coefficient of determination (R2) of 0.804. A total of 281.0 MWh were obtained from the flow prediction and PAT selection methodology, in contrast to 230.5 MWh using the actual measured data. An overall difference of 0.2% was obtained when both PATs were simulated under actual conditions.
Wastewater Pump Control under Mechanical Wear
Fecarotta, O., Martino, R., & Morani, M. C. (2019). Wastewater Pump Control under Mechanical Wear. Water, 11(6), 1210.
Abstract:
With reference to a classical wet tank equipped with a wastewater submersible pump, in this research, an advanced numerical model has been used in order to obtain the optimal pump scheduling of on/off operation and variable pump speed. Then, in order to evaluate the time decay of pump performances, the mechanical wear has been artificially simulated and the performance curves have been experimentally obtained for different rotational speeds. Finally, the benefits, as well as the feasibility, of pump scheduling have been evaluated for differing operating conditions. According to the results, the optimal pump scheduling achieves large energy savings up to 43%, for soft mechanical wear. If the mechanical wear is considered, the energy savings are large as well, between 35.60% and 26.70%, for medium and hard mechanical wear, respectively. On the other hand, the limitation of such a strategy has been highlighted: the feasibility of pump scheduling is limited by the elevation of the downstream tank. According to the results, energy savings can be achieved until the elevation of the downstream tank is 67% of the pressure head at the best efficiency point, whereas such percentage decreases to 50% for hard mechanical wear. Finally, the results show that plant efficiency is strongly affected by the mechanical wear: an accurate maintenance of the pumping system is therefore recommended in order to attenuate the time decay of pump performances.
Optimal energy efficiency of isolated PAT systems by SEIG excitation tuning
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João F.P. Fernandes, Modesto Pérez-Sánchez, F. Ferreira da Silva, P. Amparo López-Jiménez, Helena M. Ramos, P.J. Costa Branco, Optimal energy efficiency of isolated PAT systems by SEIG excitation tuning, Energy Conversion and Management, Volume 183, 2019,Pages 391-405 Abstract: The use of pump working as turbine (PAT) was identified by many researchers as a way to improve the energy efficiency in the water systems. However, the majority of the researches consider the hydraulic machine connected to the electrical grid, which may not fit best when these recovery systems are located in rural or remote areas. To improve the efficiency in these recovery systems for rural areas, this research contributes for a further study and optimization of the off-grid PAT systems with induction generators. The current manuscript proposes a methodology to obtain the best efficiency of the PAT-SEIG (Self-Excited Induction Generator) system when operating under different speeds and loads. For these systems, the selection of capacitors for the SEIG is critical to maximizing the energy efficiency. A methodology is proposed to estimate and select the correct SEIG model parameters and, thus, compute the best capacitor values to improve the PAT-SEIG energy efficiency. Special attention is given to the impact the SEIG parameters have in the efficiency of the recovery system. The accuracy of the analytical model improved, reducing the error between analytical and experimental results from 50.8% (for a model with constant parameters) to 13.2% (with parameters changing according to the operating point of the system). These results showed an increase of the overall PAT system efficiency from 26% to 40% for the analyzed case study. |
Flow Conditions for PATs Operating in Parallel: Experimental and Numerical Analyses
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Simão, M.; Pérez-Sánchez, M.; Carravetta, A.; Ramos, H.M. Flow Conditions for PATs Operating in Parallel: Experimental and Numerical Analyses. Energies 2019, 12, 901. Abstract Micro-hydro systems can be used as a promising new source of renewable energy generation, requiring a low investment cost of hydraulic, mechanical, and electrical equipment. The improvement of the water management associated with the use of pumps working as turbines (PATs) is a real advantage when the availability of these machines is considered for a wide range of flow rates and heads. Parallel turbomachines can be used to optimize the flow management of the system. In the present study, experimental tests were performed in two equal PATs working in parallel and in single mode. These results were used to calibrate and validate the numerical simulations. The analysis of pressure variation and head losses was evaluated during steady state conditions using different numerical models (1D and 3D). From the 1D model, the installation curve of the system was able to be defined and used to calculate the operating point of the two PATs running in parallel. As for the computational fluid dynamics (CFD) model, intensive analysis was carried out to predict The performance in parallel design conditions show a peak efficiency with less shock losses within the impeller. Furthermore, by combining multiple PATs in parallel arrangement, a site’s efficiency increases, covering a wide range of applications from the minimum to the maximum flow rate. The simulated flow rates were in good agreement with the measured data, presenting an average error of 10%. |
Cost Model for Pumps as Turbines in Run-of-River and In-Pipe Microhydropower Applications
D. Novara; A. Carravetta; A. McNabola; and H. M. Ramos, Cost Model for Pumps as Turbines in Run-of-River and In-Pipe Microhydropower Applications, Journal of Water Resources Planning and Management, Vol. 145, Issue 5 (May 2019), ISSN (print): 0733-9496 | ISSN (online): 1943-5452
Abstract
Pumps as Turbines (PATs) are standard water pumps utilized as hydraulic turbines by reversing the flow direction across them. The off-the-shelf availability of water pumps and their reduced purchase price with respect to conventional hydro turbines makes them an ideal technology for exploiting large portions of uncapped hydro potential that is technically viable but not financially convenient.
Such low-cost technology could help to expand hydropower exploitation in water resources worldwide, helping to reduce climate change greenhouse gas emissions. However, in the literature, the few available cost figures relative to PAT purchase price are discordant and often outdated, and such a lack of information is likely a severe barrier to a more widespread PAT implementation.
In order to overcome this limitation, data from 343 pumps and 286 generators were compiled to show graphically and analytically how the purchase price of PATs varies over different nominal powers and hydraulic conditions. Besides, a set of equations was developed to allow designers to predict the PAT and generator cost from the nominal flow rate and available hydraulic head.
Pump-as-Turbine Selection Methodology for Energy Recovery in Irrigation Networks: Minimising the Payback Period
Miguel Crespo Chacón, Juan Antonio Rodríguez Díaz, Jorge García Morillo and Aonghus McNabola,
Pump-as-Turbine Selection Methodology for Energy Recovery in Irrigation Networks: Minimising the Payback Period (2019),
Water 2019, 11(1), 149
Abstract
In pressurized irrigation networks, energy reaches around 40% of the total water costs. Pump-as-Turbines (PATs) are a cost-effective technology for energy recovery, although they can present low efficiencies when operating outside of the best efficiency point (BEP). Flow fluctuations are very important in on-demand irrigation networks. This makes flow prediction and the selection of the optimal PAT more complex. In this research, an advanced statistical methodology was developed, which predicts the monthly flow fluctuations and the duration of each flow value. This was used to estimate the monthly time for which a PAT would work under BEP conditions and the time for which it would work with lower efficiencies. In addition, the optimal PAT power for each Excess Pressure Point (EPP) studied was determined following the strategy of minimising the PAT investment payback period (PP). The methodology was tested in Sector VII of the right bank of the Bembézar River (BMD), in Southern Spain. Five potential sites for PAT installation were found. The results showed a potential energy recovery of 93.9 MWh and an annual energy index per irrigated surface area of 0.10 MWh year−1 ha−1. Renewable energy will become increasingly important in the agriculture sector, to reduce both water costs and the contribution to climate change. PATs represent an attractive technology that can help achieve such goals.
Flow Velocity Distribution Towards Flowmeter Accuracy: CFD, UDV, and Field Tests
Mariana Simão, Mohsen Besharat, Armando Carravetta and Helena M. Ramos, (2018) Flow Velocity Distribution Towards Flowmeter Accuracy: CFD, UDV, and Field Tests, Water 2018, 10, 1807; doi:10.3390/w10121807
Abstract
Inconsistences regarding flow measurements in real hydraulic circuits have been detected. Intensive studies stated that these errors are mostly associated to flowmeters, and the low accuracy is connected to the perturbations induced by the system layout. In order to verify the source of this problem, and assess the hypotheses drawn by operator experts, a computational fluid dynamics (CFD) model, COMSOL Multiphysics 4.3.b, was used. To validate the results provided by the numerical model, intensive experimental campaigns were developed using ultrasonic Doppler velocimetry (UDV) as calibration, and a pumping station was simulated using as boundary conditions the values measured in situ. After calibrated and validated, a new layout/geometry was proposed in order to mitigate the observed perturbations.
A Comparison of Energy Recovery by PATs against Direct Variable Speed Pumping in Water Distribution Networks
Maria Cristina Morani, Armando Carravetta, Giuseppe Del Giudice, Aonghus McNabola and Oreste Fecarotta; A Comparison of Energy Recovery by PATs against Direct Variable Speed Pumping in Water Distribution Networks; Fluids 2018, 3(2), 41; doi:10.3390/fluids3020041
Hydro-power energy recovery in pressurized irrigation networks
Garcia Morillo, J., McNabola, A., Camacho, E., Montesisnos, P., Rodriguez-Diaz, J.A., Hydro-power energy recovery in pressurized irrigation networks: A case study of an Irrigation District in the South of Spain., Agricultural Water Management, 204, 2018, p17 - 27
Electrical behaviour of the pump working as turbine in off grid operation
Capelo, B; Pérez-Sánchez, M; Fernandes, JFP; Ramos, H.M; López-Jiménez, P.A; Costa Branco, P.J. Electrical behaviour of the pump working as turbine in off grid operation, Applied Energy 2017, 208, 302-311
CFD Analyses and Experiments in a PAT Modeling
Pérez-Sánchez, M.; Simão, M.; López-Jiménez, P.A.; Ramos, H.M. CFD Analyses and Experiments in a PAT Modeling: Pressure Variation and System Efficiency. Fluids 2017, 2, 51.
Urban Floods Adaptation and Sustainable Drainage Measures
Ramos, H.M.; Pérez-Sánchez, M.; Franco, A.B.; López-Jiménez, P.A. Urban Floods Adaptation and Sustainable Drainage Measures. Fluids 2017, 2, 61.
Velocities in a Centrifugal PAT Operation: Experiments and CFD Analyses
Simão M, Pérez-Sánchez M, Carravetta A, López-Jiménez P, Ramos HM. Velocities in a Centrifugal PAT Operation: Experiments and CFD Analyses. Fluids. 2018; 3(1):3.