DSpace Angular :: Browsing by Author "Mocholi-Arce, Manuel"

Browsing by Author "Mocholi-Arce, Manuel"

Now showing 1 - 20 of 34

A comprehensive assessment of energy efficiency of wastewater treatment plants: An efficiency analysis tree approach
(2023) Maziotis, Alexandros; Sala-Garrido, Ramon; Mocholi-Arce, Manuel; Molinos-Senante, Maria; CEDEUS (Chile)
Wastewater treatment plants (WWTPs) are energy intensive facilities. Controlling energy use in WWTPs could bring substantial benefits to people and environment. Understanding how energy efficient the wastewater treatment process is and what drives efficiency would allow treating wastewater in a more sustainable way. In this study, we employed the efficiency analysis trees approach, that combines machine learning and linear programming techniques, to estimate energy efficiency of wastewater treatment process. The findings indicated that considerable energy inefficiency among WWTPs in Chile existed. The mean energy efficiency was 0.287 suggesting that energy use should cut reduce by 71.3 % to treat the same volume of wastewater. This was equivalent to a reduction in energy use by 0.40 kWh/m3 on average. Moreover, only 4 out of 203 assessed WWTPs (1.97 %) were identified as energy efficient. It was also found that the age of treatment plant and type of secondary technology played an important role in explaining energy efficiency variations among WWTPs.
Assesing the influence of environmental variables on the performance of water companies: An efficiency analysis tree approach
(2023) Molinos-Senante, Maria; Maziotis, Alexandros; Sala-Garrido, Ramon; Mocholi-Arce, Manuel
Efficiency assessment is a valuable tool for industries that are regulated, such as the provision of drinking water. Hence, past research on this topic is wide. However, current, widely used approaches such as parametric, non -parametric and partial frontier methods present several limitations and pitfalls. Thus, here, the Efficiency Analysis Tree (EAT) method was trialled on a sample of water companies. This method overcomes overfitting issues, because it employs a combination of classification, regression tree methods, and non-parametric analyses. For comparative purposes, efficiency was also estimated using Data Envelopment Analysis (DEA) and Free Disposal Hull (FDH) non-parametric methods. The approach was applied empirically using a sample of English and Welsh water companies during 1991-2020. Average efficiency was estimated at 0.489, showing that water companies could save 51.1% of their costs if efficient. Except for the 2011-2015 period, efficiency increased over time, indicating that price reviews by the English and Welsh water regulator contributed to improving water company performance. The application of bootstrap regression analysis techniques showed that the main source of raw water, percentage of metered properties, population density, and percentage of water leakage represented environmental variables that significantly influenced the efficiency scores of water companies. The approach introduced here could be of use to water regulators, as it overcomes the existing limitations of traditional ap-proaches employed to assess the performance of water companies, facilitating sound decision-making.
Assessing eco-efficiency of wastewater treatment plants: A cross-evaluation strategy
(2023) Sala-Garrido, Ramon; Maziotis, Alexandros; Mocholi-Arce, Manuel; Molinos-Senante, Maria
Evaluating the eco-efficiency of wastewater treatment plants (WWTPs) is crucial for enhancing environmental and economic performance in the water utility sector. Previous studies in this area estimated WWTP eco-efficiency through self-evaluation, which might have led to overestimation and biased policy recommenda-tions. To address these issues, this study applies a cross-evaluation strategy, combining self-evaluation and peer -evaluation, to assess the eco-efficiency of WWTPs. The empirical application focuses on a sample of Spanish WWTPs, yielding the following key findings. Average eco-efficiency scores were 0.353 and 0.230, for self -evaluation and global peer-evaluation approaches, respectively, confirming the overestimation of eco-efficiency scores based on self-evaluation. If WWTPs were eco-efficient, they could potentially reduce green-house gas (GHG) emissions by up to 0.39 kg CO2eq/year. The application of reliable methods, such as peer -evaluation, for eco-efficiency assessment of WWTPs provides water regulators with a comprehensive under-standing of the environmental and economic performance of WWTPs. This knowledge guides decision-making, policy development, and resource allocation, facilitating sustainable and efficient wastewater management practices.
Assessing the dynamic eco-efficiency of Italian municipalities by accounting for the ownership of the entrusted waste utilities
(2021) Romano, Giulia; Molinos Senante, María; Carosi, Laura; Llanquileo Melgarejo, Paula Iris; Sala-Garrido, Ramón; Mocholi-Arce, Manuel
This study evaluates and compares the dynamic eco-efficiency of municipalities with publicly owned, privately owned, and mixed ownership solid waste utilities by estimating the Meta-frontier Malmquist-Luenberger productivity index for a sample of 68 major Italian towns. On average, the eco-productivity of Italian waste service providers increased by 8% from 2016 to 2019. Although municipalities with private utilities improved their ecoproductivity most, the differences among the three clusters reflecting utility ownership are not statistically significant. The results show that publicly owned waste operators drive technology and that the technological levels of private utilities have deteriorated relative to global technological progress.
Assessing the marginal cost of reducing greenhouse gas emissions in the English and Welsh water and sewerage industry: A parametric approach
(2021) Sala-Garrido, Ramon; Mocholi-Arce, Manuel; Molinos-Senante, Maria; Maziotis, Alexandros
Reducing greenhouse gas (GHG) emissions involves effort from different sectors of the economy, including the water and sewerage industry. This study estimates the marginal cost of curtailing GHG emissions in the water and sewerage industry using stochastic frontier analysis techniques for a sample of ten English and Welsh water and sewerage companies over the 2010-2019 period. Results illustrated that the average marginal cost of reducing GHG emissions was 0.181 pound/Kg CO2 equivalent. The marginal cost estimated notably differs across companies and over time. Findings further illustrate the impact of water companies' operating characteristics on the marginal cost of reducing carbon emissions.
Assessment of the economic and water leakage efficiency in Chilean urban water utilities
(2024) Molinos-Senante, Maria; Maziotis, Alexandros; Sala-Garrido, Ramon; Mocholi-Arce, Manuel
This study evaluates the economic and water leakage efficiency (ELE) of a sample of Chilean water companies using efficiency analysis trees (EAT). The potential savings in operating costs and leakage could reach a level of 58%. This is equivalent to a reduction in operating costs of & POUND;391.5 million per year and in water leakage of 20.6 million cubic metres per year. A downward trend in ELE scores was observed from 2007 to 2018. It was revealed that customer density and the source of raw water had a statistically significant impact on the ELE of water companies.
Benchmarking the Performance of Productive Units Using Cross-Efficiency Techniques: An Empirical Approach for Water Companies
(2023) Sala-Garrido, Ramon; Mocholi-Arce, Manuel; Molinos-Senante, Maria; Smyrnakis, Michail; Maziotis, Alexandros
Water companies provide essential services to society, such as drinking water and sanitation. Improving the management of these companies is fundamental for evaluating their performance. This study employs cross-efficiency data envelopment analysis techniques to assess a sample of water companies during the years 2010-2018. The assessment focuses on three main topics: i) the impact of service quality on water companies' performance; ii) the influence of environmental variables on efficiency and eco-efficiency in water companies and; iii) the effect of ownership on water company performance. The results reveal that service quality significantly influences water companies' performance. Additionally, it demonstrates that customer density and ownership of water companies impact economic and environmental efficiency, with public water companies showing the best performance. However, the quality of service of public water companies had deteriorated over time.
Benchmarking the performance of water companies for regulatory purposes to improve its sustainability
(2023) Sala-Garrido, Ramon; Mocholi-Arce, Manuel; Maziotis, Alexandros; Molinos-Senante, Maria; CEDEUS (Chile)
The regulation of water companies (WCs) is essential to protect the interests of citizens, as companies are natural monopolies. Consequently, several methodological approaches are applied by water regulators to benchmark the performance of WCs, with data envelopment analysis (DEA) being one of the most widely applied. However, traditional DEA models allocate different weights to variables considered in efficiency assessments of each WC. By contrast, this study proposes and applies a common set weights (CSW) DEA model to a sample of Chilean WCs. The results showed that the DEA-CSW approach had greater discriminatory capacity compared to traditional DEA techniques. Moreover, weights allocated to input and output variables involved in efficiency assessment diverged among WCs when the traditional DEA model was employed. By contrast, the DEA-CSW approach generated reliable ranking of WCs based on their efficiency scores, thus facilitating the regulatory decision-making process.
Carbon efficiency analysis in the provision of drinking water: Estimation of optimal greenhouse gas emissions
(2023) Maziotis, Alexandros; Sala-Garrido, Ramon; Mocholi-Arce, Manuel; Molinos-Senante, Maria
Assessing carbon efficiency (CE) in the provision of drinking water services is essential to achieve a net-zero greenhouse gas (GHG) urban water cycle. Previous studies evaluating the CE of water companies are very scarce and employed parametric and non-parametric. Both methodological approaches present limitations such as overfitting issues or require assumptions about the production technology which could lead to less reliable efficiency scores. To overcome these limitations, in this study, and for the first time, we estimated CE of English and Welsh water companies using the Efficiency Analysis Trees (EAT) approach. This technique brings together machine learning and non-linear programming techniques to estimate production frontier and efficiency scores. It also allowed us to quantify the optimal level of GHG emissions in the provision of water services and estimate potential GHG savings. Bootstrap truncated regression methods were employed to quantify the impact of operating characteristics on CE of water companies. The optimal level of GHG emissions was estimated to be between 0.062 and 133.03 tons of CO2 equivalent (CO2eq) per year and per connected property. The average CE was at the level of 0.632. This means that GHG emissions could reduce by 36.8% to maintain the same level of water services. Equivalently, this corresponds to a reduction of 488,321 tons of CO2eq per year. Water only companies exhibited a better performance than water and sewerage companies with an average CE of 0.785 and 0.540, respectively. The performance of the English and Welsh water companies decreased over time. In 2011 the average CE was 0.772 whereas it went down to 0.534 in 2020. It was also estimated that on average water companies could reduce 0.034 tons of CO2eq per cubic meter of drinking water supplied and 16.16 tons of CO2eq/ connected property per year. The regression results showed that topography and water treatment complexity had a significant impact on CE. The conclusions of this study are relevant for policy makers to define policies toward a low-carbon urban water cycle.
Changes to The Productivity of Water Companies: Comparison of Fully Private and Concessionary Water Companies
(2021) Maziotis, Alexandros; Sala-Garrido, Ramon; Mocholi-Arce, Manuel; Molinos-Senante, Maria
The water industry encompasses a wide variety of water companies operating with different production technologies. This study evaluated and compared changes to the productivity of several fully private water companies (FPWCs) and concessionary water companies (CWCs). Specifically, the cost Malmquist productivity index was estimated by integrating inputs, outputs and environmental variables. A non-parametric approach was used by applying data envelopment analysis. This approach allowed us to quantify the parameters driving changes to productivity as cost efficiency change (technical and allocative efficiency), cost scale efficiency and cost technical change (technical change and input price effect). Through breaking down the cost Malmquist productivity index, relevant information for supporting decision making process by water companies is possible. To further evaluate the impact of water company heterogeneity on productivity change, the changes (convergence versus divergence) to productivity between group and meta-frontiers was estimated. The approach was applied empirically on a sample of 22 water companies in Chile during 2010-2017. The results showed that the productivity of both FPWCs and CWCs improved over time, with FPWCs performing better compared to CWCs. The main drivers of productivity growth for both types of water companies were scale efficiency, technical efficiency and input price effect. Thus, water companies in Chile could improve productivity by moving to a cost-efficient allocation of their resources. The rate of productivity convergence was higher for CWCs compared to FPWCs. The approaches developed in this study provide information that could be used by water managers to better understand what drives productivity and, thus, delineate strategies to improve performance over time.
Comparing Operational, Environmental and Eco-Efficiency of Water Companies in England and Wales
(2021) Sala-Garrido, Ramon; Mocholi-Arce, Manuel; Molinos-Senante, Maria; Maziotis, Alexandros
The assessment of performance of water companies is essential for their regulation. In doing so, several variables and models can be employed. This study evaluates and compares the performance of a sample of English and Welsh water companies from the operational, environmental and eco-efficiency perspectives by applying the non-radial data envelopment analysis range adjusted measure model. This methodological approach allows integrating greenhouse gas emissions as undesirable output. The results indicated that the water industry performed well from an operational perspective. However, environmental inefficiency considerably exists which illustrates the difficulties of the water companies in reducing greenhouse gas emissions. The average eco-efficiency was 0.783 which means that while expanding water services, water companies could further reduce costs and carbon emissions by 11.7% on average. Other factors such as water treatment complexity and population density significantly affect water companies' eco-efficiency. Several policy implications are finally discussed.
Cost and quality of service performance in the Chilean water industry: A comparison of stochastic approaches
(2023) Maziotis, Alexandros; Sala-Garrido, Ramon; Mocholi-Arce, Manuel; Molinos-Senante, Maria; CEDEUS (Chile)
The evaluation of efficiency can be of great value to water companies and regulators to adopt policies and design incentives to enhance performance. This study delves into the implications of employing distinct methodologies, namely the classical Stochastic Frontier Analysis (SFA), Bayesian SFA, and Stochastic non-parametric Envelopment of Data (StoNED), to evaluate cost and quality of service efficiency within the water industry. Chilean water companies reported average efficiencies of 0.623, 0.583, and 0.522 using the SFA, BSFA, and StoNED approaches, respectively. Furthermore, the SFA analysis suggested that the performance of water companies experienced a decline of -0.59% per year from 2010 to 2018. In contrast, the BSFA and StoNED estimations indicated an opposite trend, with annual performance improvements of 0.51% and 0.17% respectively, over the same period. These findings underscore the critical role of selecting appropriate methodologies when interpreting and comparing efficiency results for making informed long-term decisions.
Eco-efficiency assessment under natural and managerial disposability: an empirical application for Chilean water companies
(2023) Sala-Garrido, Ramon; Mocholi-Arce, Manuel; Molinos-Senante, Maria; Maziotis, Alexandros
Getting a good understanding regarding the economic and environmental performance of water utilities is of great importance to achieve the goal of an efficient and sustainable industry. In this study, we apply the range adjusted measure (RAM) data envelopment analysis (DEA) model to evaluate the integrated (production and environmental) efficiency of several water utilities located in Chile. Integrated efficiency is evaluated using the concepts of natural and managerial disposability. This approach further allows us to quantify the contribution of each input and undesirable product on efficiency scores. The results highlighted that the Chilean water industry showed high levels of production and environmental efficiency over time. Under natural disposability, water utilities could control production costs to reduce water leakage and unplanned water supply interruptions by 3.3% on average. Under managerial disposability, water utilities could further cut down undesirable outputs by 1.4% on average by adopting best managerial practices. On average, potential savings in operating costs, employment, water leakage, and unplanned water supply interruptions were higher for concessionary utilities as they showed slightly lower efficiency scores than full private utilities.
Eco-Efficiency of the English and Welsh Water Companies: A Cross Performance Assessment
(2021) Sala-Garrido, Ramon; Mocholi-Arce, Manuel; Molinos-Senante, Maria; Smyrnakis, Michail; Maziotis, Alexandros
Analyzing costs and greenhouse gas (GHG) emissions could be of great importance for the water utilities to supply water services in a healthy and sustainable manner. In this study, we measured the eco-efficiency of several water utilities in England and Wales by incorporating GHG as an undesirable output. For the first time, we evaluated the eco-efficiency of the water production process using robust cross-efficiency data envelopment analysis (DEA) techniques. The further use of clustering and regression techniques allowed us to better understand the drivers of eco-efficiency. The results showed that the mean eco-efficiency of the water sector was 0.748, which indicates that costs and GHG emissions could be reduced by 25.2% to generate the same level of output. Large water companies with high energy costs and levels of GHG emissions belonged to the less eco-efficient group. Environmental factors related to density, topography, and treatment complexity further impacted eco-efficiency. Finally, we linked our results to the regulatory cycle and discuss some policy implications.
Energy efficiency of drinking water treatment plants: A methodologicalapproach for its ranking br
(2023) Maziotisa, Alexandros; Mocholi-Arce, Manuel; Sala-Garrido, Ramon; Molinos-Senante, Maria; CEDEUS (Chile)
Drinking water treatment systems (DWTSs) are energy intensive facilities, and are an example of the water-energynexus. Benchmarking energy efficiency is a valuable tool for improving the economic and environmental performanceof such facilities. Data envelopment analysis (DEA) is typically used to assess efficiency, allocatingflexible weights(FSW) to variables that maximise energy efficiency scores for each DWTS (DEA-FSW). It means that different condi-tions are applied to each DWTS. Moreover, the DEA-FSW approach hasfinite discriminatory power which limitscross-unit comparison of energy efficiency hindering the benchmarking of DWTSs. To overcome these limitations,our study explored the effect of estimating the energy efficiency scores of DWTSs by allocating common sets of weights(CSW) within DEA (DEA-CSW). This approach was applied empirically on a sample of 146 DWTSs. Evaluated DWTSshad poor energetic performance based on both DEA-FSW and DEA-CSW estimates (low energy efficiency scores: 0.329and 0.163, respectively). Even in the optimistic scenario, the average energy efficiency score was low (0.220), withpotential electricity savings of 78 % by DWTPs when energy efficient. Unlike DEA-FSW, DEA-CSW allowed energyefficient DWTSs to be distinguished from the 146 facilities. Significant differences in the weights allocated to electric-ity and pollutants removed from raw water were reported for both approaches, and contributed to diverging energyefficiency scores. In conclusion, this study demonstrated the relevance of using suitable methods to generate compa-rable results for water companies, allowing the energy performance of DWTSs to be objectively evaluated forbenchmarking purposes
Estimating energy costs and greenhouse gas emissions efficiency in the provision of domestic water: An empirical application for England and wales
(2022) Molinos-Senante, Maria; Maziotis, Alexandros; Mocholi-Arce, Manuel; Sala-Garrido, Ramon
Reducing greenhouse gas (GHG) emissions and energy costs has been one of the main challenges faced by the water sector. This study provides a quantification of energy costs and GHG emissions efficiency of a sample of the English and the Welsh water companies over the period of 2013-2018. In doing so, the multi-directional data envelopment analysis (DEA) method was employed, which allows the quantification of the potential savings in energy costs and GHG emissions, i.e. defining the targets to be set by the water regulators. In the second stage of the analysis, bootstrap techniques were applied to identify environmental variables influencing the performance of water companies. The results indicate that the efficiency of the English and the Welsh water companies was low since the average efficiency scores for energy costs and GHG emissions were 0.644 and 0.415, respectively. It reveals that the water sector might save 35.6% and 58.6% of the current energy costs and GHG emissions. The study's findings demonstrated that the source of raw water, the treatment required to produce drinking water and population density were the environmental variables influencing the efficiency of these water companies in terms of energy costs and GHG emissions. The evidence provided by this study is of great interest to water regulators and water companies to implement policies and measures towards a low-carbon urban water cycle.
Estimating performance and savings of water leakages and unplanned water supply interruptions in drinking water providers
(2022) Molinos-Senante, Maria; Maziotis, Alexandros; Sala-Garrido, Ramon; Mocholi-Arce, Manuel
Water leakages and unplanned water supply interruptions are relevant variables in the provision of drinking water since they directly impact customers and the economic and environmental performance of water com-panies. For the first time, in this study, we estimated specific efficiency scores for these two quality-of-service variables using the multi-directional data envelopment analysis technique for a sample of 21 Chilean water companies over the 2007-2018 period. Unlike previous studies, this methodological approach allowed us to estimate potential savings for both quality-of-service variables. The results indicate that the Chilean water in-dustry could improve its efficiency over water leakage and unplanned water supply interruption by 28.6% and 52.5%, respectively, while supplying the same volume of drinking water. It is estimated that water companies could save around 48 million cubic metres of drinking water per year. Savings on unplanned water supply in-terruptions for the Chilean water industry are estimated to be at the level of 62,419 h per year.
Estimating the cost efficiency and marginal cost of carbon reductions in the production of drinking water
(2022) Molinos-Senante, Maria; Maziotis, Alexandros; Sala-Garrido, Ramon; Mocholi-Arce, Manuel
Access to safe, reliable and affordable drinking water is a human right that should be achieved without neglecting Sustainable Development Goal 13 of the United Nations related to climate action. The production of drinking water involves using a non-negligible amount of energy, leading to relevant economic costs and greenhouse gas (GHG) emissions. Here, we employed a parametric method to assess the cost efficiency of a sample of drinking water treatment plants (DWTPs) and to estimate the marginal cost of reducing GHG emissions. The average cost efficiency was 0.386, indicating that the evaluated DWTPs had notable room (61.4%) to save costs. The average marginal cost was estimated at 30 euro per ton of CO2(eq). When comparing this value with the current carbon costs of carbon trading systems, reducing the GHG emissions of DWTPs might be cost-effective. The parametric approach enabled us to evaluate the influence of several environmental variables on the cost efficiency and marginal cost of reducing GHG emissions. Specifically, the size of the facility and source of raw water significantly influenced DWTP performance. In conclusion, this study provides a novel tool to obtain in-sights on the water-energy nexus for informed decisions towards a more sustainable urban water cycle.
Estimating the impact of carbon inefficiency and overuse of energy on the economics of water companies: A case study for England and Wales
(2024) Maziotis, Alexandros; Sala-Garrido, Ramon; Mocholi-Arce, Manuel; Molinos-Senante, Maria
In the face of climate change, it becomes crucial to motivate action and policies within water companies towards achieving carbon neutrality. Estimating the economic consequences of inaction can be a compelling catalyst for change. In this study, the carbon inefficiency and overuse of energy among a selection of English and Welsh water companies were assessed, along with their impact on the operational costs of producing and delivering drinking water over the period from 2010 to 2019. In doing so, a stochastic frontier analysis primal system was employed. The findings revealed that, on average, water companies exhibited a carbon inefficiency of 0.699. The overuse of energy relative to other inputs was estimated to be 71.4%. Consequently, water companies incurred a production cost increase of 0.089 pound/m3. This research demonstrates that transitioning towards a low-carbon urban water cycle is not merely an environmental beneficial endeavor; it also involves significant economic advantages.
Estimation of greenhouse gases shadow price in the English and Welsh water industry
(2022) Maziotis, Alexandros; Sala-Garrido, Ramon; Mocholi-Arce, Manuel; Molinos-Senante, Maria
Moving to a more sustainable and low-carbon footprint urban water cycle is essential in the light of climate change. In this paper, we estimate the implicit cost of reducing greenhouse gas (GHG) emissions for several English and Welsh water companies from 2013 to 2019. Using econometric techniques, we compute the shadow prices of direct and indirect CO2 emissions associated with the provision of drinking water. This methodological approach also allows us to investigate the impact of a set of environmental variables on the costs of water companies and therefore on the costs of reducing GHG emissions. We then compute the returns to scale, technical change, and technical efficiency of the water companies. The empirical results show the following: (1) the average shadow price of CO2 across years was 0.114 pound/kgCO(2), which means that the English and Welsh water industry needs to spend an extra 0.114 pound in operating expenditure to prevent the emission of one kilogramme of CO2; (2) the cost of reducing GHG emissions is very variable among water companies and across years; (3) water taken from boreholes and average pumping head increases cost requirements and therefore the inefficiency of water companies; and (4) the water industry may lower its production costs and thus the costs of reducing GHG emissions by improving its daily operations and adopting new technologies. From a policy perspective, this study evidences that in the English and Welsh water industry, a market-based approach may be more suitable to reduce GHG emissions than a carbon tax policy.

Browsing by Author "Mocholi-Arce, Manuel"

Results Per Page

Sort Options