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Urban Generation of Renewable Energy and Sustainable Cities

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A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (30 September 2016) | Viewed by 36848

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Prof. Dr. Francisco Manzano Agugliaro

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Department of Engineering, University of Almeria, CeiA3, 04120 Almeria, Spain
Interests: remote sensing; UAV; land cover; land use; sustainability; agriculture; land change; energy; engineering; water
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Special Issue Information

Dear Colleagues,

The world population will probably exceedind eleven billion by the end of the century. Most of this population lives in urban areas. Our quickly changing world faces great challenges when it comes to the sustainable provision of energy. Despite its huge potential for increasing sustainability, the use of renewable energy in urban places is still scarce. This perspective highlights the urban contribution to renewable energy, which will be essential for the welfare of a growing urban population. This Special Issue aims to advance in the contribution of Urban Generation of Renewable Energy in order to achieve more sustainable cities. This Special Issue seeks contributions spanning a broad range of topics related, but are not limited, to:

Solar flat plate collectors
Stand alone PV
Solar collector
Effects of dust or sand on the materials used in solar systems
Wind turbines for rooftop of a building
Energy conversion from urban biomass or residues
Energy management for sewage water
Bioclimatic architecture and green buildings
Public and private urban energy saving
Policy for urban energy saving
District heating
Sustainable cities

Prof. Dr. Francisco Manzano-Agugliaro
Guest Editors

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Keywords

sustainable cities
energy policy
green buildings
district heating
wind energy
solar energy
biomass

Published Papers (7 papers)

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Research

3341 KiB

Open AccessArticle

Profitability Variations of a Solar System with an Evacuated Tube Collector According to Schedules and Frequency of Hot Water Demand

by Carlos J. Porras-Prieto, Susana Benedicto-Schönemann, Fernando R. Mazarrón and Rosa M. Benavente

Energies 2016, 9(12), 1053; https://doi.org/10.3390/en9121053 - 14 Dec 2016

Cited by 7 | Viewed by 3216

Abstract

The use of solar water heating systems with evacuated tube collectors has been experiencing a rapid growth in recent years. Times when there is demand for hot water, the days of use and the volumes demanded may determine the profitability of these systems, even within the same city. Therefore, this paper characterizes the behavior of a solar system with active circulation with the objective of determining the profitability variations according to the timing and schedule of demand. Through a simplified methodology based on regression equations, calculated for each hour of the day based on data from an experimental facility, the useful energy is estimated from the time and frequency of the demand for hot water at 60 °C. The analysis of the potential profitability of the system in more than 1000 scenarios analyzed shows huge differences depending on the number of days when the water is demanded, the time when demand occurs, the irradiation and the average price of energy. In cities with high irradiation and high energy prices, the system could be profitable even in homes where it is used only on weekends. The study of profitability in a building of 10 homes shows that by applying an average European household’s profile for hot water demand, levels close to full potential would be reached; for this, it is necessary to optimize the collection surface. Full article

(This article belongs to the Special Issue Urban Generation of Renewable Energy and Sustainable Cities)

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13947 KiB

Open AccessEditor’s ChoiceArticle

Soiling and Cleaning of Polymer Film Solar Reflectors

by Christopher Sansom, Aránzazu Fernández-García, Florian Sutter, Heather Almond, Peter King and Lucía Martínez-Arcos

Energies 2016, 9(12), 1006; https://doi.org/10.3390/en9121006 - 29 Nov 2016

Cited by 17 | Viewed by 6192

Abstract

This paper describes the accelerated ageing of commercially available silvered polymer film by contact cleaning using brushes and water in the presence of soiling created by dust and sand particles. These conditions represent cleaning regimes in real concentrating solar power (CSP) solar fields in arid environments, where contact cleaning using brushes and water is often required to clean the reflecting surfaces. Whilst suitable for glass reflectors, this paper discusses the effects of these established cleaning processes on the optical and visual characteristics of polymer film surfaces, and then describes the development of a more benign but effective contact cleaning process for cleaning polymer reflectors. The effects of a range of cleaning brushes are discussed, with and without the presence of water, in the presence of sand and dust particles from selected representative locations. The experiments were repeated using different experimental equipment at Plataforma Solar de Almería (PSA) in Spain and Cranfield University in the UK. The results highlight differences that are attributable to the experimental methods used. Reflectance measurements and visual inspection show that a soft cleaning brush with a small amount of water, used in a cleaning head with both linear and rotational motion, can clean polymer film reflecting surfaces without inflicting surface damage or reducing specular reflectance. Full article

(This article belongs to the Special Issue Urban Generation of Renewable Energy and Sustainable Cities)

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6679 KiB

Open AccessEditor’s ChoiceArticle

Comparison of Degradation on Aluminum Reflectors for Solar Collectors due to Outdoor Exposure and Accelerated Aging

by Johannes Wette, Florian Sutter, Aránzazu Fernández-García, Stefan Ziegler and Reinhard Dasbach

Energies 2016, 9(11), 916; https://doi.org/10.3390/en9110916 - 5 Nov 2016

Cited by 14 | Viewed by 5530

Abstract

Reflectors for concentrated solar thermal technologies need to withstand 20 or even 30 years of outdoor exposure without significant loss of solar specular reflectance. In order to test the durability of innovative reflectors within a shorter period of time, an accelerated aging methodology is required. The problem with accelerated testing is that poor correlation between laboratory and field test results has been achieved in the past. This is mainly because unrealistic degradation mechanisms are accelerated in the weathering chambers. In order to define a realistic testing procedure, a high number of accelerated aging tests have been performed on differently coated aluminum reflectors. The degradation mechanisms of the accelerated tests have been classified and systematically compared to samples that have been exposed at nine different exposure sites outdoors. Besides the standardized aging tests, innovative aging procedures have been developed in such way that the agreement to the degradation pattern observed outdoors is increased. Although degradation depends on materials and location, five generic degradation mechanisms were detected. Standardized tests only reproduced one or two of the five mechanisms detected outdoors. Additionally, several degradation effects that were not observed outdoors appeared. The innovative accelerated aging tests of artificially soiled samples were able to reproduce three of the five mechanisms observed outdoors, presenting a much more realistic overall degradation pattern. Full article

(This article belongs to the Special Issue Urban Generation of Renewable Energy and Sustainable Cities)

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14080 KiB

Open AccessArticle

Solar Resource for Urban Communities in the Baja California Peninsula, Mexico

by Alberto-Jesús Perea-Moreno and Quetzalcoatl Hernandez-Escobedo

Energies 2016, 9(11), 911; https://doi.org/10.3390/en9110911 - 3 Nov 2016

Cited by 5 | Viewed by 6755

Abstract

Several studies have determined that Mexico has great renewable energy potential, and one of its most abundant resources is solar energy, a source that could be exploited to provide development opportunities to its population, however it is necessary to calculate the amount of this source available. The aim of this study was to assess solar irradiance at urban communities in the Baja California Peninsula. For this purpose data recorded every 10 min during 6 years (2010–2015) by the Automatic Meteorological Stations (AMSs) and Synoptic Automatic Meteorological Stations (SAMSs) of the National Meteorological System of Mexico (NMS) were analyzed. Satellite data from the Surface and Meteorology Energy System (SMSE) were also used, and a linear regression was performed to compare the measured and satellite data. The highest R-square value found was 0.97 and the lowest was 0.82. Daily patterns show that Cabo San Lucas had the highest average solar irradiation/day, with 1000 W/m². Considering the urban areas, total solar irradiation reaching the Peninsula is about 447 × 10⁶ kWh, which represents around 447 times the total Baja California Peninsula yearly energy consumption. Geographic Information System (GIS) helped to identify the zones and months with higher solar resources. May is the month registering the highest irradiation, more than 8.1 kWh/m²/day, while the average solar resource for the whole Peninsula is 5.7 kWh/m²/day. Full article

(This article belongs to the Special Issue Urban Generation of Renewable Energy and Sustainable Cities)

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26032 KiB

Open AccessArticle

Wind Energy Assessment for Small Urban Communities in the Baja California Peninsula, Mexico

by Quetzalcoatl Hernandez-Escobedo

Energies 2016, 9(10), 805; https://doi.org/10.3390/en9100805 - 9 Oct 2016

Cited by 12 | Viewed by 5517

Abstract

Mexico needs to exploit its renewable resources and many studies have determined the great renewable potential it has using wind energy. However it is necessary to calculate the amount of this resource for small urban communities, which in this country lack essential services such as electricity. This study is focused in the Baja California Peninsula, using GIS as a tool to identify small urban zones with higher wind power. For this work data was analyzed from meteorological stations and recorded every 10 min for two years (2012–2014). Weibull distribution, linear regression, kriging interpolation, power and energy output and useful hours were calculated for each station. It was found that the total energy generated is 38,603,666 kWh per year and the mean of useful hours is 5220 h per year for the whole Peninsula. Maps of Wind Power Density (WPD) show a good power per square meter, GIS shows the areas with the most wind power where it can be used i.e., the state of Baja California wind power can generate electricity for 12% of those communities, meanwhile for Baja California Sur, the electric power generation could electrify almost 25% of the total of small urban communities. Full article

(This article belongs to the Special Issue Urban Generation of Renewable Energy and Sustainable Cities)

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1397 KiB

Open AccessArticle

A Design Alternative to Improve the Interconnection Capability of New Distributed-Generation Installations into Existing Griddle

by José Agüero-Rubio, Javier López-Martínez, José Ignacio Rojas-Sola and Ángel Jesús Callejón-Ferre

Energies 2016, 9(6), 416; https://doi.org/10.3390/en9060416 - 27 May 2016

Cited by 1 | Viewed by 3612

Abstract

Most distributed-generation facilities are performed on pre-built distribution grids. The design conditions of these existing grids may limit the ability of new users to get a connection due to technical and/or cost constraints. This work proposes a simple solution, adjusted to the relevant regulations and embodied in a radial distribution grid of Spanish low voltage, to improve the interconnection of distributed generation, usually grid connected photovoltaic systems. The proposed solution, based on increasing the section of the neutral line, achieves a capacity of increasing the length of the supply grid by more than 20%. Full article

(This article belongs to the Special Issue Urban Generation of Renewable Energy and Sustainable Cities)

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3094 KiB

Open AccessArticle

Modeling of Production and Quality of Bioethanol Obtained from Sugarcane Fermentation Using Direct Dissolved Sugars Measurements

by Borja Velazquez-Marti, Sergio Pérez-Pacheco, Juan Gaibor-Chávez and Paola Wilcaso

Energies 2016, 9(5), 319; https://doi.org/10.3390/en9050319 - 26 Apr 2016

Cited by 3 | Viewed by 5146

Abstract

Bioethanol production from sugarcane represents an opportunity for urban-agricultural development in small communities of Ecuador. Despite the fact that the industry for bioethanol production from sugarcane in Brazil is fully developed, it is still considered expensive as a small rural business. In order to be able to reduce the costs of monitoring the production process, and avoid the application of expensive sensors, the aim of this research was modeling the kinetics of production of bioethanol based on direct measurements of Brix grades, instead of the concentration of alcohol, during the process of cane juice bio-fermentation with Saccharomyces cerevisiae. This avoids the application of expensive sensors that increase the investment costs. Fermentation experiments with three concentrations of yeast and two temperatures were carried out in a laboratory reactor. In each case Brix grades, amount of ethanol and alcoholic degree were measured. A mathematical model to predict the quality and production of bioethanol was developed from Brix grade measurements, obtaining an adjusted coefficient of determination of 0.97. The model was validated in a pilot plant. Full article

(This article belongs to the Special Issue Urban Generation of Renewable Energy and Sustainable Cities)

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