A novel thermal water pump for circulating water in a solar water heating system

This research purpose was to perform a parametric study of a novel thermal water pump well fitted in a simulated solar water heating system (SWHS). The SWHS was composed of a heating tank (HT), a hot water storage tank (ST) and an overhead tank (OT). The HT together with a specially designed valve act as a novel thermal water pump that gets power from hot water vapor and air pressure produced by a built-in electric heater in order to transfer heat from the HT to ST. The general operation of this pump has four stages for each cycle: heating, water circulating, vapor circulating and water supplying. The discharge water heads were varied with an increment of 0.25 m from 0.75 to 3 m. According to the experiment, it was found that the pump could operate at an average HT temperature of about 80–95 °C leading to 70–80 °C ST temperatures and 20–35 pumping cycles and consumed 17 MJ energy input during 9-h period. The overall thermal efficiency of the SWHS was 33–42% and the mean pump efficiency was about 0.005–0.011% depending upon the discharge heads.     

Geothermal energy potentials in the province of Vojvodina from the aspect of the direct energy utilization

The interest in increasing the participation of renewable energy sources (RES) in energy production arises with increasing population and growing demands for energy production and consumption, as well as the fact of the limited fossil fuels reserves. RES in the energy balance of any country has their share of energy, socio-economic and environmental benefits. Investment in energy sector in the RES domain enables Vojvodina Province to reduce energy dependence on the fossil fuel market.From the total RES potential in Vojvodina Province that is 1293 ktoe/year, around 1.7% is located in existing geothermal sources. There are 73 drills with a total capacity of 72.6 MW from which 65 drills are tested positive. Currently, 15 wells are in production, with a total power of 17.7 MW. There are 27 drills that have never been in production and which are perspective, with a total power of 42.8 MW.The aim of this paper is to perform data analysis of direct geothermal energy utilization according to the water temperature and geothermal fluid flow. According to the results of the analysis recommendations for geothermal energy utilization are given within certain sectors: agriculture (aquaculture and greenhouses), heating of the facilities and pools, industrial applications and balneology.     

Feasibility of the green energy production by hybrid solar + hydro power system in Europe and similar climate areas

This paper analyses the hybrid solar and hydro (SHE) system as a unique technological concept of the sustainable energy system that can provide continuous electric power and energy supply to its consumers and the possibilities of its implementation in Europe and areas with similar climate. The sustainability of such system is based on solar photovoltaic (PV) and hydroelectric (HE) energy as renewable energy sources (RES). For the purpose of connecting all relevant values into one integral SHE system, a mathematical model was developed for selecting the optimal size of the PV power plant as the key element for estimating the technological feasibility of the overall solution. Sensitivity analysis (parameter analysis) was made for the model, where local climate parameters were varied: solar radiation, air temperature, reservoir volume, total head, precipitation, evaporation and natural water inflow. It has been established that, apart from total head (which is to be expected), solar radiation, hydro accumulation size and natural water inflow have the biggest effect on the calculated power of the PV power plant. The obtained results clearly show a wide range of implementation of the new energy source (SHE system), i.e. from relatively cold climates to those abundant in solar energy, but also with relatively small quantity of water, because it only recirculates within the system. All this points to the necessity for further development of hybrid systems (RES + HE systems) and to the fact that they could play an important role in achieving climate objectives.     

Application of Sayigh “Universal Formula” for global solar radiation estimation in the Niger Delta region of Nigeria

In recent years, renewable energy utilisation in various applications has increased significantly. Applications involving solar thermal energy include air and water heating whilst solar photovoltaic systems have been installed to provide electricity for households in urban and rural areas of the developing economies. The solar radiation data are not easily available for many countries and is therefore estimated most of the times. In this work is presented the results of evaluating the Sayighr “Universal formula” for estimating the global solar radiation in the Niger Delta region of Nigeria with Umudike (longitude 7.33°E, latitude 5.29°N) as a case study. The levels of the global solar radiation which ranged from 1.99 kWh to 6.75 kWh, computed with the method are in agreement with those of earlier authors indicating that the method can be used for reproducing signatures of global solar radiation in the region when actual measurements are not available.     

Spatial mapping of renewable energy potential

An energy resource that is renewed by nature and whose supply is not affected by the rate of consumption is often termed as renewable energy. The need to search for renewable, alternate and non-polluting sources of energy assumes top priority for self-reliance in the regional energy supply. This demands an estimation of available energy resources spatially to evolve better management strategies for ensuring sustainability of resources. The spatial mapping of availability and demand of energy resources would help in the integrated regional energy planning through an appropriate energy supply–demand matching. This paper discusses the application of Geographical Information System (GIS) to map the renewable energy potential talukwise in Karnataka State, India. Taluk is an administrative division in the federal set-up in India to implement developmental programmes like dissemination of biogas, improved stoves, etc. Hence, this paper focuses talukwise mapping of renewable energy (solar, wind, bioenergy and small hydroenergy) potential for Karnataka using GIS. GIS helps in spatial and temporal analyses of the resources and demand and also aids as Decision Support System while implementing location-specific renewable energy technologies.Regions suitable for tapping solar energy are mapped based on global solar radiation data, which provides a picture of the potential. Coastal taluks in Uttara Kannada have higher global solar radiation during summer (6.31 kWh/m²), monsoon (4.16 kWh/m²) and winter (5.48 kWh/m²). Mapping of regions suitable for tapping wind energy has been done based on wind velocity data, and it shows that Chikkodi taluk, Belgaum district, has higher potential during summer (6.06 m/s), monsoon (8.27 m/s) and winter (5.19 m/s). Mysore district has the maximum number of small hydropower plants with a capacity of 36 MW. Talukwise computation of bioenergy availability from agricultural residue, forest, horticulture, plantation and livestock indicates that Channagiri taluk in Shimoga district yields maximum bioenergy. The bioenergy status analysis shows that Siddapur taluk in Uttara Kannada district has the highest bioenergy status of 2.004 (ratio of bioresource availability and demand).     

Thermal analysis for system uses solar energy as a pressure source for reverse osmosis (RO) water desalination

As Natural resources are becoming limited and energy price dramatically increased, energy utilization with efficient systems is essentially required to be used in desalination technologies. The use of solar energy in desalination processes is one of the most promising applications of renewable energies. The primary focus on desalination by solar energy is suitable for use in remote areas. A proposed desalination system uses solar radiation, which concentrated by parabolic dish to heat up the working fluid in a closed space. Then the generated pressure in this space used to push salt water into RO module.Daily production rate of fresh water quantity for suggested system compared with other solar techniques is a promising rate for each m² of solar radiation collecting surface. The production rate for one operation cycle could reach to 1800 L/cycle of fresh water at low water salinity (Brackish water with 5000 ppm) and 55 L/cycle at highest water salinity (sea water salinity with 42,000 ppm). The required energy needed to produce 1 kg of fresh water is also promising even when in case of using another type of energy, also operating cycle has ability of repetition according to salinity concentration through sunny hours.     

Biogas generation potential by anaerobic digestion for sustainable energy development in India

The potential of biogas generation from anaerobic digestion of different waste biomass in India has been studied. Renewable energy from biomass is one of the most efficient and effective options among the various other alternative sources of energy currently available. The anaerobic digestion of biomass requires less capital investment and per unit production cost as compared to other renewable energy sources such as hydro, solar and wind. Further, renewable energy from biomass is available as a domestic resource in the rural areas, which is not subject to world price fluctuations or the supply uncertainties as of imported and conventional fuels. In India, energy demand from various sectors is increased substantially and the energy supply is not in pace with the demand which resulted in a deficit of 11,436 MW which is equivalent to 12.6% of peak demand in 2006. The total installed capacity of bioenergy generation till 2007 from solid biomass and waste to energy is about 1227 MW against a potential of 25,700 MW. The bioenergy potential from municipal solid waste, crop residue and agricultural waste, wastewater sludge, animal manure, industrial waste which includes distilleries, dairy plants, pulp and paper, poultry, slaughter houses, sugar industries is estimated. The total potential of biogas from all the above sources excluding wastewater has been estimated to be 40,734 Mm³/year.     

Performance evaluation method of solar-assisted heat pump water heater

The present study derives a simple linear correlation for the performance evaluation of different solar-assisted heat pump water heater (ISAHP). The correlation was derived from the principle of energy conservation with some simplifications. The correlation is then verified using the long-term outdoor field test data of four different ISAHP. The problems of seasonal repeatability and method of data scattering were examined. From that, a standard performance test method is proposed. The test method suggests that only the measurement of instantaneous solar incident radiation on horizontal surface, ambient temperature, hot water temperature in the storage tank, total mass of water in the storage tank and total power input to the ISAHP are required. It is suggested to select the value of COP at T_f − T_a,ave = 15 °C as the characteristic COP for performance comparison of ISAHP. It is found from the test results that the same performance correlation holds for ISAHP operating with single or dual energy source.     

Hydropower for sustainable energy development in Turkey: The small hydropower case of the Eastern Black Sea Region

Turkey is a rich country from the point of variety and potential of renewable energy resources. Hydros, winds, biomass, solar and geothermal are important renewable and environmentally friendly sources for energy in Turkey. Turkey produces large amount of hydropower with a total gross hydropower potential of 433 TW h/yr, which is equal to 13.8% of the total hydropower potential of Europe. Technically useable potential is 216 TW h/yr and economic potential is 140 TW h/yr. The main aim of the present study is to investigate hydropower potential of Turkey and small hydropower plants in Eastern Black Sea Region for sustainable energy development in Turkey. The geography of Turkey especially, Eastern Black Sea Region supports and suitable the development of the small hydro plants to increase the energy generation and utilization of available water sources in Turkey. Besides, the paper deals with hydropower policies to meet ever increasing energy demand for sustainable development of Turkey.     

Efficiency of PET reactors in solar water disinfection for use in southeastern Brazil

Solar water disinfection using the solar water disinfection (SODIS) method is not a well-known technique in Brazil. The objective of the study was to investigate the effectiveness of a solar energy concentrator made of cardboard and covered with aluminium foil in heating water in transparent and black-backed PET reactors and to compare the efficiency of these reactors with those that are used on asbestos roofing. The efficiency of the method was evaluated for a year with monthly in loco readings and through analysis of the local weather where the study was performed. The black-backed PET reactors in the solar concentrator were better at heating water than any of the other treatments, both on strong and moderate weather days. On weak weather days, however, these reactors did not heat the water enough for solar disinfection to take place. Disinfection of polluted river water samples was evaluated in black-backed solar reactors. The most probable number (MPN) of thermotolerant coliform bacteria and Escherichia coli in water collected from the river were measured using the multiple tube fermentation technique before and after solar treatment. River water samples exposed to 3 h of solar radiation on moderate weather days had 99.9% inactivation of faecal coliforms (E. coli) when the water reached more than 50 °C (average 6 h peaks of radiation – 685.6 W/m²). However, inactivation of faecal coliforms was not observed in reactors exposed to solar radiation in the same weather conditions on asbestos roofing. A computer simulation of water heating was carried out using a dynamic fluid model based on the diffusion equation. The computational model produced temperature values similar to the experimental curves (r² = 0.99). The results suggest that using a specific radiation data set, the behaviour of water temperature in the PET reactors can be accurately predicted. Therefore, it may be possible to make predictions about water purification by the SODIS method in southeastern Brazil, where there are similar weather conditions.     

Optimizing rainwater harvesting systems as an innovative approach to saving energy in hilly communities

Rapid urbanization is increasing the amount of hilly communities around many large cities; therefore, saving water pumping energy deserves significant priority. This work proposes optimized rooftop rainwater harvesting systems (RRWHSs) and provides an energy-saving approach for hilly communities. The most cost-effective rainwater tank volumes for different dwelling types are calculated using marginal analysis. The case study at Hua-Chan Community in northern Taiwan indicates that the optimum rainwater tank volumes range from 5 m³ to 10 m³ according to the type of dwelling. The results also reveal that rainwater harvesting becomes economically feasible when both energy and water savings are addressed together. Furthermore, the cost of unit energy saving from RRWHSs is lower than that from solar PV systems. Hence, RRWHSs provide not only water savings, but also as an alternative renewable energy-saving approach to address the water–energy dilemma caused by the ever-growing hilly communities.     

Assessment of renewable energy resources potential for electricity generation in Bangladesh

Renewable energy encompasses a broad range of energy resources. Bangladesh is known to have a good potential for renewable energy, but so far no systematic study has been done to quantify this potential for power generation. This paper estimates the potential of renewable energy resources for power generation in Bangladesh from the viewpoint of different promising available technologies. Estimation of the potential of solar energy in Bangladesh is done using a GIS-based GeoSpatial Toolkit (GsT), Hybrid System Optimization Model for Electric Renewables (HOMER) model and NASA Surface Meteorology and Solar Energy (SSE) solar radiation data. The potential of wind energy is estimated by developing a Bangladesh wind map using NASA SSE wind data and HOMER model. A review of country's biomass and hydro potential for electricity generation is presented. The technical potential of gird-connected solar PV is estimated at 50,174 MW. Assuming that 1000 h per year of full power is the feasible threshold for the exploitation of wind energy, the areas that satisfy this condition in the country would be sufficient for the installation of 4614 MW of wind power. The potential of biomass-based and small hydro power plants is estimated at 566 and 125 MW, respectively. The renewable energy resources cannot serve as alternative to conventional energy resources, yet they may serve to supplement the long-term energy needs of Bangladesh to a significant level.     

MODERGIS application: Integrated simulation platform to promote and develop renewable sustainable energy plans,Colombian case study

This research presents the MODERGIS Integrated Simulation's Platform as a tool to promote and develop renewable energy plans under sustainability criteria, in order to increment the participation of renewable technologies in the national “energy mix” and shows an application to Colombia as a case study. Potential zones of solar and wind energy and productive areas were determined for bio-energies, by means of a geographical information system which simulated energy scenarios influenced by climatic phenomena up to the year 2030. Results yield potentials of 26,600 MW in wind energy and 350,000 MW in solar energy. Bioenergy potentiates in a sustainable way of 366,310 km per biomass, 291,486 km in African palm, 9,667 km in sugar cane. These scenarios were simulated in a supply/demand with time horizons up until 2030, including an analysis of the effects on the energy systems of the El Niño Southern Oscillation atmospheric component (ENSO). Finally, in order to obtain an appropriate mix of renewable sources that could be introduced in the national energy mix, the Multi-Criteria Analysis method VIKOR was used, allowing to perform performing 5151 possible combinations of renewable projects; the optimal selection corresponds to 600 MW from wind power, 740 MW solar photovoltaic and 660 MW solar thermoelectric. Giving these results to the new scene allowed for incrementing the participation of renewable technologies up to a 0.23% in the current year and up to a 7% of the “energy mix” in the year 2030.     

Solar water heating potential in South Africa in dynamic energy market conditions

This paper is an attempt to determine the potential for solar water heating (SWH) in South Africa and the prospects for its implementation between 2010 and 2030. It outlines the energy market conditions, the energy requirements related to residential and commercial water heating in the country and the solar water heating market dynamics and challenges. It was estimated that 98% of the potential is in the residential sector and the rest in the commercial sector. The total thermal demand for 20 years for water heating was estimated to 2.2 EJ. A ‘Moderate SWH implementation’ will provide 0.83 EJ of clean energy until 2030 and estimated cost savings of 231 billion rand. For an ‘Accelerated SWH implementation’ these figures are 1.3 EJ and 369 billion rand. The estimated accumulated reduction of CO₂ emissions due to SWH can be as high as 297 Mt. The increased affordability of residential hot water due to SWH is an important social factor and solar water heating has a strong social effect.     

Performance of a dual-purpose solar continuous adsorption system

A conceptual design and performance of a dual-purpose solar continuous adsorption system for domestic refrigeration and water heating is described. Malaysian activated carbon and methanol are used as the adsorbent–adsorbate pair. The heat rejected by the adsorber beds and condensers during the cooling process of the refrigeration part is recovered and used to heat water for the purpose of domestic consumption. In a continuous 24-h cycle, 16.9 MJ/day of heat can be recovered for heating of water in the storage tanks. In the single-purpose intermittent solar adsorption system, this heat is wasted. The total energy input to the dual-purpose system during a 24-h operation is 61.2 MJ/day and the total energy output is 50 MJ/day. The latter is made up of 44.7 MJ/day for water heating and 5.3 MJ/day for ice making. The amount of ice that can be produced is 12 kg/day. Using typical value for the efficiency of evacuated tube collector of water heating system of 65%, the following coefficient of performances (COP's) are obtained: 44% for adsorption refrigeration cycle, 73% for dual-purpose solar water heater, 9.1% for dual-purpose solar adsorption refrigeration and 82.1% for dual-purpose of both solar water heater and refrigerator.     

Utilization of phase change materials in solar domestic hot water systems

Thermal energy storage systems which keep warm and cold water separated by means of gravitational stratification have been found to be attractive in low and medium temperature thermal storage applications due to their simplicity and low cost. This effect is known as thermal stratification, and has been studied experimentally thoughtfully. This system stores sensible heat in water for short term applications. Adding PCM (phase change material) modules at the top of the water tank would give the system a higher storage density and compensate heat loss in the top layer because of the latent heat of PCM. Tests were performed under real operating conditions in a complete solar heating system that was constructed at the University of Lleida, Spain. In this work, new PCM-graphite compounds with optimized thermal properties were used, such as 80:20 weight percent ratio mixtures of paraffin and stearic acid (PS), paraffin and palmitic acid (PP), and stearic acid and myristic acid (SM). The solar domestic hot water (SDHW) tank used in the experiments had a 150 L water capacity. Three modules with a cylindrical geometry with an outer diameter of 0.176 m and a height of 0.315 m were used. In the cooling experiments, the average tank water temperature dropped below the PCM melting temperature range in about 6–12 h. During reheating experiments, the PCM could increase the temperature of 14–36 L of water at the upper part of the SDHW tank by 3–4 °C. This effect took place in 10–15 min. It can be concluded that PS gave the best results for thermal performance enhancement of the SDHW tank (74% efficiency).     

A case study of underground thermal storage in a solar-ground coupled heat pump system for residential buildings

This paper presents a case study of underground thermal storage in a solar-ground coupled heat pump system (SGCHPS) for residential buildings. Based on the experimental results, the operation performance is simulated by the unit modelling. The results show that the performance of underground thermal storage of SGCHPS depends strongly on the intensity of the solar radiation and the matching between the water tank volume and the area of solar collectors. Compared with the solar radiation, the variations of the water tank temperature and the ground temperature raise lag behind and keep several peaks during the day time. In the present study, the experimental efficiency of underground thermal storage based on the absorbed solar energy by the collectors reaches 76%. For the similar design of SGCHPS, it is suggested that the optimal ratio between the tank volume and the area of solar collectors should range from 20 to 40 L/m².     

As a renewable energy hydropower for sustainable development in Turkey

The most important renewable sources are hydropower, biomass, geothermal, solar and wind. Turkey's geographical location has several advantages for extensive use of most of these renewable energy sources. In recently, electricity has demand increased significantly; it is the fastest growing end-use of energy. Therefore, technical, economic and environmental benefits of hydroelectric power make it an important contributor to the future world energy mix. In the world, particularly in the developing countries renewable energy resources appear to be one of the most efficient and effective solutions for sustainable energy development in Turkey. Turkey's geographical location has several advantages for extensive use of most of the renewable energy sources. This paper deals with policies to meet increasing energy and electricity demand for sustainable energy development in Turkey. Turkey has a total gross hydropower potential of 433 GWh/year, but only 125 GWh/year of the total hydroelectric potential of Turkey can be economically used.     

Renewable energy deployment in Europe up to 2030 and the aim of a triple dividend

Renewable energy sources (RES) play a key role in the European Commission's 2030 Climate and Energy Framework, which aims for a low-carbon economy that increases the security of the EU's energy supplies and creates new opportunities for growth and jobs, among other benefits. We assess whether renewable energy deployment in Europe can provide this “triple dividend”, at which ambition levels of 2030 RES targets and what the role of the support policy scheme for electricity is. We apply two types of models: a detailed techno-economic sector model of the deployment of RES and two macroeconomic models. Our findings suggest that up to 2030 our triple-dividend hypothesis holds even under a declining role of Europe as technology provider for the rest of the world. Additional emission reductions of up to 1040 Mt CO₂, as compared to a baseline scenario in 2030, are possible. Demand for fossil fuels can likewise be reduced due to the deployment of renewable energy sources by up to 150 Mtoe. More ambiguous is the order of magnitude of the effects on GDP and employment, which differs noticeably depending on the economic theory applied in the different models. Nevertheless, both models predict slightly higher GDP and employment in 2030 when implementing ambitious RES targets.     

Economic evaluation of hybrid renewable energy systems for rural electrification in Iran—A case study

The Binalood region in Iran enjoys an average wind speed of 6.82 m/s at 40 m elevation and an average daily solar radiation of 4.79 kWh/m²/day. Within this perspective, a remote rural village in Binalood region, called Sheikh Abolhassan, can readily be expected to have more than enough potential for its load demand to be supplied with a stand-alone hybrid renewable energy system. Yet the local state-run electrical service provider extended the utility grid to the village in 2006 to boost the already present diesel generator. This study aims, firstly, to explore how economical it would have been to keep supplying the electricity of the village by the diesel generator and add renewable energy generators to increase the renewable fraction of the system. On a second stage, we tried to investigate how renewable energy sources (RESs) can still be added to the current utility grid power supply in Sheikh Abolhassan to achieve a more economical and environmentally friendly system. The software HOMER is used in this study to evaluate the feasibility of various hybrid diesel-RES and grid-RES energy systems. Findings indicated that the addition of renewable power generators to the system both before and after the grid extension could and still can result in a more economical power system, which is obviously cleaner and more climate-benign.