Hybrid solar–wind domestic power generating system—a case study

A techno-economic study to design a hybrid solar photo-voltaic-wind domestic power generating system for a site on the western coast of India is described. The system uses short-term electrical power storage using lead-acid batteries, and auxiliary power from the A.C. mains power supply.The optimum system would be able to supply 84.16% of the annual electrical energy requirement of the site. The annualized cost of this power in Rs./kwh works out to be several times the present price of government supplied electricity.     

A method for estimating direct normal solar irradiation from satellite data for a tropical environment

In order to investigate a potential use of concentrating solar power technologies and select an optimum site for these technologies, it is necessary to obtain information on the geographical distribution of direct normal solar irradiation over an area of interest. In this work, we have developed a method for estimating direct normal irradiation from satellite data for a tropical environment. The method starts with the estimation of global irradiation on a horizontal surface from MTSAT-1R satellite data and other ground-based ancillary data. Then a satellite-based diffuse fraction model was developed and used to estimate the diffuse component of the satellite-derived global irradiation. Based on this estimated global and diffuse irradiation and the solar radiation incident angle, the direct normal irradiation was finally calculated. To evaluate its performance, the method was used to estimate the monthly average hourly direct normal irradiation at seven pyrheliometer stations in Thailand. It was found that values of monthly average hourly direct normal irradiation from the measurements and those estimated from the proposed method are in reasonable agreement, with a root mean square difference of 16% and a mean bias of −1.6%, with respect to mean measured values. After the validation, this method was used to estimate the monthly average hourly direct normal irradiation over Thailand by using MTSAT-1R satellite data for the period from June 2005 to December 2008. Results from the calculation were displayed as hourly and yearly irradiation maps. These maps reveal that the direct normal irradiation in Thailand was strongly affected by the tropical monsoons and local topography of the country.     

The impact of the daylight saving time on electricity consumption—A case study from Jordan

The paper examines the impact of daylight saving time (DST) on electricity consumption in Jordan. Two types of analysis were done: the first analysis examines the impact of DST on the lighting loads based on a survey study made for residential and commercial sectors. The second examines the impact of DST on the over all electricity generation through analyzing the daily load curves (DLCs) before and after the DST onset and removal in 2000 and 2007. The results show that the application of DST during the year 2000 saves the electricity used for illumination by −0.73% but it increases the overall generation at the onset and removal of DST by 0.5% and 1.4% due to increase in the heating and cooling loads. The analysis of DLCs during the year 2007 shows similar effects as in the year 2000 except during the early morning period at the DST onset where DST decreases the demand during this time. The analysis shows that DST decreases the electricity demand at DST onset by 0.2% and increases it at DST removal by 0.3%. A possible decrease in the electricity consumption may take place if the DST is implemented from April to end of August.     

Economic analysis of power generation from parabolic trough solar thermal plants for the Mediterranean region—A case study for the island of Cyprus

In this work a feasibility study is carried out in order to investigate whether the installation of a parabolic trough solar thermal technology for power generation in the Mediterranean region is economically feasible. The case study takes into account the available solar potential for Cyprus, as well as all available data concerning current renewable energy sources policy of the Cyprus Government, including the relevant feed-in tariff. In order to identify the least cost feasible option for the installation of the parabolic trough solar thermal plant a parametric cost–benefit analysis is carried out by varying parameters, such as, parabolic trough solar thermal plant capacity, parabolic trough solar thermal capital investment, operating hours, carbon dioxide emission trading system price, etc. For all above cases the electricity unit cost or benefit before tax, as well as after tax cash flow, net present value, internal rate of return and payback period are calculated. The results indicate that under certain conditions such projects can be profitable.     

Development of a method for generating operational solar radiation maps from satellite data for a tropical environment

Despite a considerable number of publications which use satellite data to map solar radiation, relatively few studies have been undertaken in a tropical environment. In this study, we have developed a method to produce operational solar radiation maps from satellite data for this environment. The method is based on a physical model which relates the satellite-derived earth–atmospheric reflectivity from visible channel of GMS-4 and GMS-5 to the transmissivity of the atmosphere. Cloud reflectivity was determined from satellite data, while radiation absorbed by water vapour, ozone and aerosols and radiation scattered by aerosols were determined from ground-based meteorological data. Techniques for determining the radiation depleted by these atmospheric constituents over a whole country were also presented. Satellite data of a six-year period (1993–1998) with approximately ten thousand satellite images were used to construct the maps. When tested against an independent data set, monthly average of daily global irradiation calculated from this method agree with that obtained from the measurements with the relative root mean square difference of 6.8% with respect to the mean values. Solar radiation is presented as twelve maps showing the monthly average of global irradiation and one map showing the yearly average of global irradiation. Radiation patterns from the maps show a strong influence of the tropical monsoons.     

Comparison of methods for generating typical meteorological year using meteorological data from a tropical environment

This paper presents the comparison of methods for generating typical meteorological year (TMY) data set using a 10-year period of meteorological data from four stations in a tropical environment of Thailand. These methods are the Sadia National Laboratory method, the Danish method and the Festa and Ratto method. In investigating their performance, these methods were employed to generate TMYs for each station. For all parameters of the TMYs and the stations, statistical test indicates that there is no significant difference between the 10-year average values of these parameters and the corresponding average values from TMY generated from each method. The TMY obtained from each method was also used as input data to simulate two solar water heating systems and two photovoltaic systems with different sizes at the four stations by using the TRNSYS simulation program. Solar fractions and electrical output calculated using TMYs are in good agreement with those computed employing the 10-year period hourly meteorological data. It is concluded that the performance of the three methods has no significant difference for all stations under this investigation. Due to its simplicity, the method of Sandia National Laboratories is recommended for the generation of TMY for this tropical environment. The TMYs developed in this work can be used for solar energy and energy conservation applications at the four locations in Thailand.     

The economics of a solar/diesel hybrid — A case study

The energy system, discussed, was a typical hybrid where a farmer decided that with the escalating cost of diesel as well as the logistics attached to the supply of diesel to his farm, adding a photovoltaic array to his diesel based system would make economic sense. A study of the energy consumption in comparison with the cost input for different scenarios was carried out.     

The economics of energy efficiency for the poor—a South African case study

South Africa’s Reconstruction and Development Programme set ambitious goals for providing basic services to all, including housing and electrification. More efficient use of energy has the potential to socially and politically support these goals, particularly when it is targeted at low-income communities lacking adequate energy services. This paper examines the economics of energy efficiency for the urban poor from the perspective of society, utilities and poor consumers, using five example programmes. While the five energy efficiency programmes generally have significant economic and environmental benefits from a social perspective, they may not be as attractive to utilities and consumers. Also examined are the policy options for overcoming the significant barriers to energy efficiency, and ways government can bridge the gap between what is good for society and what is good for the electricity industry.     

Evaluation of the thermodynamic analysis of hydrogen production from a middle-temperature intensity solar collector,a case study

In today, the basic necessity for the economic and social development of countries is to have a cheap, reliable, sustainable, and environmentally friendly energy source. For this reason, renewable energy sources stand out as the most important key. Solar energy-based multi-energy generation systems are one of the most important options among the current scenarios to prevent global warming. In this presented study, electricity and hydrogen production from a solar collector with medium temperature density is investigated. In this system, 34 pipes evacuated tube solar collector (ETSC) is used for thermal energy generation, organic Rankine cycle (ORC) for electricity generation, and Proton exchanger membrane electrolyzer (PEMe) for hydrogen production. In addition, the energy and exergy efficiencies of the whole system calculated as 51.82% and 16.30%, respectively. Moreover, the amount of hydrogen obtained in PEM is measured as 0.00527 kg/s.     

Ethyl ester of rapeseed used as a biodiesel fuel—a case study

A 1994 Dodge 2500 turbocharged and intercooled diesel pickup fueled with 100% ethyl ester of rapeseed oil was driven by personnel representing the University of Idaho, Agricultural Engineering Department from Moscow, Idaho to Los Angeles, California and back to Moscow and then from Moscow to Ocean City, Maryland, east of Washington, D.C. and back to Moscow, Idaho. These trips covered a total of 14,069 km (8742 miles). The truck averaged 7.76 km/l (18.7 mile/gal) using 1772 l (468 gal) of ethyl ester of rapeseed oil fuel. No problems or unusual events were encountered with the truck's operation. The truck was completely unmodified as to the engine and fuel system. The fuel required for the trip was all processed in the Agricultural Engineering Laboratory at the University of Idaho and was carried on-board as no refueling facilities were available away from Moscow, Idaho. This is believed to be the first coast-to-coast and back run on 100% biodiesel.     

Economics of solar air pre-heating in south Indian tea factories: a case study

Tea processing is an energy intensive operation requiring both thermal and electrical energy. Hot air at a temperature of 100–130°C for tea drying and withering has been obtained in the past by burning coal or firewood. Over the last four years, roof integrated solar air heating systems have been introduced in some of the tea factories of south India, as a partial energy source. This paper aims to present the economical analysis of one such system: a 212 m² collector area system that has been in operation for 2.75 yr. The system has reduced specific fuel consumption for tea production from 0.932 to 0.71 kg/kg dmt (drier mouth tea), which represents a fuel savings of approximately 25%. The economic analysis considered the annual investment cost and return cost and included concessions offered by the Government. It shows a payback period of from two to four years, depending upon whether the company is profit making or non-profit making. This work has helped to establish the economic viability of this method.     

Network benefits of embedded solar systems: A case study from western Sydney

This paper presents a simulation study based on actual load, sunshine and wind data. A distribution feeder simulation model was constructed using this data to determine what potential benefit embedded wind, solar and storage elements could give to the distribution network. The results were compared to earlier studies. It was discovered that over the past 5–10 years, the hot weather peak load has extended from 3 pm to 6 pm and that a more northwesterly orientation of solar panels is of assistance. It was also found that wind is of little assistance in hot weather peaks, in contrast to data for the NSW central tablelands region; however solar contributes at least 50% of its nominal peak capacity. As hot weather peaks are now extending into the early evening, it was found that storage would be of great benefit and would enhance the use of renewable energy sources. As part of the feeder model, the optimal method of Var control from the embedded sources was also studied.     

Measured and modelled improvement in solar energy yield from flat plate photovoltaic systems utilizing different tracking systems and under a range of environmental conditions

This work is performed to investigate the effect of using different sun tracking mechanisms on the flat plate photovoltaic system performances and the main parameters affecting the amount of their electrical energy output as well as those affecting their gains compared to the traditional fixed photovoltaic systems. To this end, five configurations of sun tracking systems and two traditional fixed panels have been considered. The sun tracking systems effect on the PV system performances is improved by using the hourly data collected over 18 days for different seasonal sky conditions. The daily cumulative electrical energy produced by the different systems have been quantified separately for each sky state and the corresponding electrical gains have then been compared to those experienced with two traditional fixed photovoltaic systems. It is found that for a completely clear day, the highest obtained gains are those related to the two-axis sun tracker systems, which decrease gradually from the inclined to the vertical rotating axis when the same optimum slope is applied and from the seasonal to the yearly optimum slope if the same rotating axis is considered. On the other hand, for the partially clear days, the gain amounts are mainly dependant on the clearness index and on the seasonal variation of day length values. For a completely cloudy day, the results show that all considered systems produced closely the same electrical energy and the horizontal position of the photovoltaic panel presented the best performance.     

The use of probability theory in fracture mechanics—A case study

A probabilistic approach to fracture mechanics in the form of a typical case study is described wherein the integrity of a high-pressure water pipeline is assessed. An analysis methodology is discussed incorporating the probability density functions of defect sizes, the statistics of defect occurrences and the statistical distribution of material properties. This method enables the analyst to supply a very simple assessment of safety, based on the probability of failure (a single number) which may be compared to accepted industrial standards (e.g. 10⁻⁶ for nuclear applications). It is argued that this method often offers the only way to scientifically and economically assess the integrity of fracture prone structures.     

Solar electricity in a changing environment: The case of Spain

In Spain, solar electricity (photovoltaic and thermoelectric) has reached a stable annual capacity factor above 20% since 2009; while wind achieved 23% since more than 10 years ago. This is the demonstration of an ongoing transition towards a more sustainable energy mix, further corroborated by the reduction of the capacity factor of gas-fired technology, which has seen a decline to values lower than 10% after an initial promising rise; this is a very low value for a fossil-fuel technology. Additionally, hydro installed capacity, which has been stable for the past 20 years, have demonstrated that can be used as a back-up power source in combination with solar and wind electricity, and it is capable of producing energy peaks that may increase from a stable base of 2000 GWh/month up to 6000 GWh/month and therefore meet demand at some particular times when solar and wind are generating less electricity without the need of installing new additional capacity at national level.     

The environmental impacts of arable coppice power generation — A case study from Cornwall, UK

This paper is concerned with the assessment of the environmental impacts associated with a 2.5MW biopower station, fuelled by arable coppice, to be developed at a rural site in Cornwall, South West England. The project represents a new form of energy production for the UK and the first one of its type to be subject to environmental assessment in this country. The study was carried out on behalf of South Western Power Ltd and in support of its application for planning consent to build and operate the facility. The environmental assessment (EA) was comprehensive and reviewed the possible impacts of the plant on air and water quality; noise; landscape; socio economics, ecology and cultural heritage. Impacts during the construction phase were also considered.The study concluded that, with the exception of visual amenity, the plant would have no significant environmental impacts. Mitigation measures to reduce visual impacts in the form of landscaping around the site were introduced to reduce visual intrusion. Positive benefits would be derived through employment potential and through reductions in greenhouse gases and other polluting emissions. The development of this type of renewable energy plant would represent a significant step towards establishing a new type of environmental benign energy production method in the UK.     

Techno-economic analysis and optimization of a proposed solar-wind-driven multigeneration system; case study of Iran

This paper performs a thermo-economic assessment of a multi-generation system based on solar and wind renewable energy sources. This system works to generate power, freshwater, and hydrogen, which consists of the following parts: the solar collectors, Steam Rankine subsystem, Organic Rankine subsystem, desalination part, and hydrogen production and compression unit. Initially, the effects of variables including reference temperature, solar radiation intensity, wind speed, and solar cycle mass flow rate, which depend on weather conditions and affect the performance of the integrated system, were investigated. The thermodynamic analysis results showed that the overall study's exergy efficiency, the rate of hydrogen and freshwater production, and total cost rate are 33.3%, 7.92 kg/h, 1.6398 kg/s, and 61.28 $/h, respectively. Also, the net power generation rate in the Steam and Organic Rankine subsystems and wind turbines are 315 kW, 326.52 kW, and 226 kW, respectively. The main goal of this study is to minimize the total cost rate of the system and maximize the exergy efficiency and hydrogen and freshwater production rate of the total system. The results of optimization showed that the exergy efficiency value improved by 20.7%, the hydrogen production rate increased by 1%, and the total cost rate value declined by 2%. Moreover, the optimum point is similar to a region in Hormozgan province, Iran. So, this region is proposed for building the power plant.     

Role of a district-heating network as a user of waste-heat supply from various sources – the case of Göteborg

District-heating (DH) networks can utilise heat that would otherwise be of limited use. This study analyses a municipal DH system, which uses waste heat from industries and waste incineration as base suppliers of heat and is currently investing in a natural-gas fired combined heat-and-power (CHP) plant. An important assumption in this study is of the establishment of an integrated European electricity-market, which means higher electricity prices than are traditional in Sweden. The study shows that there is space in the DH system for all three energy carriers; heat from industries, waste incineration and CHP plants. The new CHP plant replaces mainly other heat sources, i.e., hot water boilers and heat pumps. The new CHP plant’s operating time is strongly dependent on the electricity price.     

Numerical models of HDR geothermal reservoirs—a review of current thinking and progress

A brief review is presented of modelling and simulation of HDR geothermal reservoirs both for hydraulic fracturing/stimulation to create artificial/engineered geothermal reservoirs and for long-term heat extraction operations. Firstly, modelling of the governing factors is surveyed and coupling among mechanical, thermal, hydraulic and chemical effects is discussed. Next the structure and modelling of reservoirs are discussed. Finally, the features of a variety of simulation codes are summarized.     

Financing renewable energy projects via closed-end funds—a German case study

During recent years, closed-end funds have become one of the dominant financing schemes for wind farms in Germany. Having evolved out of the traditional model of local citizen-financed wind farms (‘Bürgerwindpark’), closed-end wind funds can be seen as a logical consequence of the increasing professionalism and specialisation trend within the wind business as a whole. This article illustrates the basic market mechanisms behind the project development and financing approach based on closed-end funds and gives an overview on recent market developments in Germany. Finally, the transferability of this approach to other technologies or other regional markets is discussed.