The current-voltage characteristics of solar cells, under
illumination and in the dark, represent a very important tool for
characterizing the performance of the solar cell. The PC-ID computer
program has been used to analyze the deviation of the dark
current-voltage characteristics of p-n junction silicon solar cells from
the ideal two-diode model behavior of the cell, namely the appearance of
“humps” in the I-V characteristics. The effects of the
surface recombination velocity, the minority carrier lifetimes in the
base and emitter regions of the solar cell, as well as the temperature
dependence of the I-V characteristics have been modeled using PC-ID. It
is shown that the “humps” in the I-V characteristics arise
as a result of recombination within the space-charge region of the solar
cell, and occur when conditions for recombination are different from the
simple assumptions of the Shockley-Read-Hall theory
A computer model and a methodology has been developed to perform
value analysis for small, low-temperature binary geothermal power
plants. The value analysis method allows for incremental changes in the
levelized energy cost (LEC) to be determined between a baseline plant
and a modified plant. Thermodynamic cycle analyses and component sizing
are carried out in the model followed by economic analysis which
provides LEC results. The emphasis of the work has been on evaluating
different types of heat rejection systems
Computer simulation is an increasingly popular tool for determining the most suitable hybrid energy system type, design and control for an isolated community or a cluster of villages. This paper presents the development of the optimum control algorithm based on combined dispatch strategies, to achieve the optimal cost of battery incorporated hybrid energy system for electricity generation, during a period of time by solving the mathematical model, which was developed in Part I. The main purpose of the control system proposed here is to reduce, as much as possible, the participation of the diesel generator in the electricity generation process, taking the maximum advantage of the renewable sources available. The overall load dispatch scenario is controlled by the availability of renewable power, total system load demand, diesel generator operational constraints and the proper management of the battery bank. The incorporation of a battery bank makes the control operation more practical and relatively easier.
Wind energy conversion systems have become a focal point in the research of renewable energy sources. This is in no small part due to the rapid advances in the size of wind generators as well as the development of power electronics and their applicability in wind energy extraction. This paper provides a comprehensive review of past and present converter topologies applicable to permanent magnet generators, induction generators, synchronous generators and doubly fed induction generators. The many different generator-converter combinations are compared on the basis of topology, cost, efficiency, power consumption and control complexity. The features of each generator-converter configuration are considered in the context of wind turbine systems
In this paper indium is examined for use as an electrical and optical dopant with the n-type silicon wafer to fabricate the In-doped silicon (n) structure. The subgap response of the resulting structure is particularly strong and extends to wavelengths up to 1100 nm, and more. While the response of the structure is very poor at the visible region. The structure has a maximum external and internal quantum efficiency at wavelength equal to 1100 nm
To date, many traditional solar home systems (SHS) have consisted of separate components which required assembly by trained individuals and were also more susceptible to failure and maintenance. As a result, many SHSs in remote areas have not fulfilled their expected lifecycles or simply have not functioned at all. Thankfully, a solution to these problems has arrived - the newly developed integrated solar home system (I-SHS). Within this new system all components such as the support structure, foundation, PV modules, charge controller, DC-AC converter and wiring are pre-assembled by the manufacturer. This eases installation and maintenance resulting in a reduction of cost and failure. Additionally, electrical yield was increased by 9% by a significant reduction of operating cell temperature. This was achieved by an integrated water tank, serving as a cooling unit and also providing the system's foundation. This measure is neither expensive nor energy intensive, improves output of the system in an unproblematic way, and also allows use of the heated water.
The BMFT and the State governments jointly started a
“Thousand Roofs Programme” in September 1990. At first, this
programme was limited to the territory of the former West Germany. In
July 1991, the extension to the new Federal States was announced. In the
programme the installation of 2250 small (1-5 kWp) grid-connected PV
systems on the roofs of one or two-family houses is being sponsored.
Federal and State grants were provided for the actual system costs to an
upper limit of DM 27000 per kWp. The grant proportion was 70%, 50% of
the system costs from Federal and 20% from State funds
Direct conversion of biomass-derived syngas (bio-syngas) to dimethyl ether (DME) at pilot-scale (100 t/a) was carried out via pyrolysis/gasification of corncob. The yield rate of raw bio-syngas was 40–45 Nm3/h with less than 20 mg/Nm3 of tar content when the feedrate of dried corncob was 45–50 kg/h. After absorption of O2, S, Cl by a series of absorbers and partial removal of CO2 by the pressure-swing adsorption (PSA) unit sequentially, the obtained bio-syngas (H2/CO≈1) was directly synthesized to DME over Cu/Zn/Al/HZSM-5 catalyst in the fixed-bed tubular reactor. CO conversion and DME space-time yield (STY) were 67.7% and 281.2 kg/mcat3/h respectively at 260 °C, 4.3 MPa and 3000 h−1(GHSV, syngas hourly space velocity). Synthesis performance would be increased if the tail gas (H2/CO > 2) was recycled to the reactor when GHSV was 650–3000 h−1.
An automatic global and direct solar spectral irradiance system has been designed based on two LICOR spectroradiometers equipped with fibre optics and remote cosine sensors. To measure direct irradiance a sun tracker based on step motors has been developed. The whole system is autonomous and works continuously. From the measurements provided by this system a spectral irradiance database in the 330–1100 nm range has been created. This database contains normal direct and global horizontal irradiances as well as diffuse irradiance on a horizontal plane, together with total atmospheric optical thickness and aerosol optical depth.
ISO 14000 has attracted interest from industry, international organizations and governments around the globe. Policy-makers and industry both appear to be looking to the standards as a key component of a new paradigm for cooperation between regulators and industry. This realization seems to have resulted from a growing awareness that the fragmented, reactive approach to environmental management in the past has not produced optimal results. Businesses are realizing the value of integrating their compliance procedures for each regulation into a broader system. Compliance problems can often be linked to system problems such as inadequate training, lack of responsibility at the right level, inadequate data, and other related causes. An effective Environmental Management System (EMS) eliminates these pitfalls. The evolution of the EMS is being shaped by market forces, ISO 9000, regulatory shifts, public awareness, and cost implications for ISO certifications. The transformation of these management practices is not limited to industrialized countries. In anticipation of the non-tariff trade barriers that could be erected as a result of these standards, many developing countries are seeking avenues of compliance with ISO 14000's requirements. Egypt should be concerned with the implementation of this system, for firms in countries of the European Community (EC) have been given explicit instructions by the three prevalent European standard-setting organizations to “familiarize” themselves with the requirements of ISO 14000. This paper will focus primarily on the expected effects of ISO 14001
The achievement of the proposed bioenergy objectives and targets for the E.U. (210 M. TOE/year ≈ 12% total gross energy consumption by the year 2010) are indeed very challenging.At present, the contribution of bioenergy is 44 M. TOE/year (∼ 3% of the total consumption). Furthermore, a significant export volume of E.U. bioenergy technology is expected as high as 6 billion ECU/year (year 2010) with the creation of many new industrial manufacturing SMEs (150–200) and about 200,000 direct and indirect new jobs. The recommended high level of bioenergy activity in the E.U. will also open many additional job opportunities (∼ 2 million in a longer term) with specific investment of about 150,000 – 230,000 ECU/job. The consequent CO2 reduction is estimated at 255 million ton/year in the year 2010.The most promising markets are: •■ the heat, with a contribution of 75 M. TOE/year is estimated•■ the power generation, with a contribution of 230 TWh/y•■ bioethanol/biomethanol (∼7 million TOE/year).
India's Renewable Energy Programme is the largest and the most extensive among the developing countries of the World. The increased use of renewable energy technologies has been facilitated by a variety of policy and support measures from the Government of India (GoI). The programme is administered by the Ministry of Non-Conventional Energy Sources (MNES) - the nodal ministry of the GoI, entrusted with the responsibility of policy making, planning, promotion and coordination of various aspects of renewable energy.The need to optimize utilization of India's vast potential for energy generation from renewables and to alleviate the severe power crunch faced by the country requires the integration of renewable energy into the national energy planning thereby enabling the creation of a balanced energy-mix. This in turn calls for taking renewable energy technologies beyond the stage of research, development and demonstration to commercialization through appropriate financing mechanisms. It was to this end that the MNES set up the Indian Renewable Energy Development Agency Ltd. (IREDA) in 1987.IREDA's mandate is to develop, promote, support and extend financial assistance to renewable energy projects. In its first decade of operation, IREDA has committed financial assistance to the tune of US$ 397 million for renewable energy projects and is the recipient of several multi-lateral and bi-lateral assistance's.The presentation will discuss the accomplishments of IREDA and the barriers faced in its efforts to support and catalyze the commercialization of renewable energy technologies through innovative and well structured programmes.
In this paper numerical simulation has been used to predict the effect of the thickness and aluminium (Al) mole fraction of an AlGaAs layer, used as a window for a p+–n–n+ GaAs solar cell under AM0 illumination and exposed to 1 MeV electron irradiation. Such solar cells are used in satellites and undergo severe degradation in their performance due to induced structural defects. The irradiation-induced defects are modelled as energy levels in the energy gap of GaAs. To predict this effect, the spectral response is evaluated for different electron irradiation fluences for two types of cells. In the first a narrow Al0.31Ga0.69As window is a small part of the p+ layer while in the second type the whole window is an AlxGa1−xAs layer with a gradual Al mole fraction. The obtained results show that the AlxGa1−xAs window with a gradual Al mole fraction improves the resistance of the solar cell to electron irradiation especially in the short wavelengths range.
Civilization has embraced a highly refined essence of culture for well over 2,000 years. Commerce and quality of life have danced in a delicate and at times bold interplay throughout the evolution of humankind. Yet, never so precariously as it does, today.The earth with its abundant blessings and resources sway on a pendulum in orbit between the drive for survival and the corruptibility of commerce. Decisions regarding global resources are now - more than ever - entwined with the very essence of global survival. We must put responsible energy products in reach and within budget, today.Sound market deployment of building-integrated photovoltaics are focused within core industrialized nations where the technology and related systems may be proven on a broad scale with closely monitored installations primarily self-financed with Solar Bond incentives. The 100 Headrick Solar-Voltaic Dome Power Stations By 2000 Program advances a unique mid-size 2,100 m2 (21,000 SF) solar array increasing peak output on an acre four times from 60 kWp to 262 kWp (at 1 kWp per 8m2) with 3,400 m2 leasable.Formal ceremonial signing of this commitment by leaders of the United States, the European Commission and Japan is an important step to encourage the commercial real estate industries of these industrialized nations to advance this Program assuring photovoltaics timely achieves status as a World Trade Commodity of the 21st Century.
EOLE 2005 has been launched in July 1996 by the French Ministry of Industry, Electricité de France and ADEME (Agency for Environment and Energy Management). The Ministries of Research and Environment are participating also in this programme. The purpose is to create an initial market in France for wind power generation in order to evaluate the cost-effectiveness and the competitiveness of the wind energy compared to other energy sources by 2005. The installed capacity will reach at least 250 MW and possibly 500 MW.
Cyprus is a small island situated in the north-eastern Mediterranean with no indigenous conventional energy sources, away from interconnected networks of electricity and gas. Recently, Cyprus won the prestigious World Renewable Energy Congress Trophy for its remarkable efforts and initiatives to increase the contribution of renewable energy sources (RES) to the county's energy mix. This paper presents the energy system of Cyprus, analyses and reviews the energy policy and the various measures taken by the government for the development and support on the use of RES in the island, which had a decisive role on the judges’ decision for the nomination of the award.
The 1993 world shipments increased only 6.7% from 57.9MW in 1992 to 60.69MW in 1993. European shipments increased 1% from 16.4MW in 1992 to 16.55MW in 1993. U..S. shipments increased 24.0% to 22.44MW and Japanese shipments decreased 8% to 17.3MW. The status of all major PV module producers will be summarized. New entrants in the thin film area include: Golden Photon (CdTe), Solar Cells Inc. (CdTe), United Solar Systems (triple-stack amorphous silicon), and B.P. Solar (CdTe). In the silicon crystal area, plant expansions have been made by Siemens Solar Industries, B.P. Solar, and Solec. New crystal silicon entrants include: Astropower, Texas Instruments, Nukem, and Gallivare. Potential capacity increases by 1996 of 75–100MW are described. Module performance (efficiency and warranty), and manufacturing costs will be summarized and forecast to 2010. In the limit, the sliced silicon product tends to approach profitable prices of $2.00 per watt, while several thin-film options and concentrators can be manufactured with profitable prices less than $1.50 per watt. The world market for PV modules is summarized by market sector and forecast to 2010 under two scenarios -- “Business as Usual” and “Accelerated“. Under the Business as Usual assumptions, world PV module shipments are forecast to be 195 MW in 2000 and 800MW in 2010. The Accelerated scenario forecasts world module shipments in 2000 to be 440 MW and 4000 MW in 2010. Module shipments for the last four years have been growing at a rate .
This paper considers biodiesel production from residues; tallow and used cooking oil (UCO). The tallow system is more complex involving two processes. The first process is rendering in which tallow (animal fat) and Meat and Bone Meal (MBM) are produced from the slaughter of cattle. MBM is assumed as a thermal energy source for cement manufacture and thus is not used for biodiesel production. The second process is biodiesel production from tallow. Three methodologies are employed to examine sustainability of the biodiesel. The no allocation approach assigns all the parasitic demands to the tallow; thus all energies required to make both MBM and tallow are associated with the tallow biodiesel. The resulting energy balance is negative. The substitution approach allocates the energy in MBM (used to produce cement) to tallow biodiesel. This results in the net energy being greater than the gross energy. The allocation by energy content method divides the parasitic demands of the rendering process between tallow and MBM by energy content. The parasitic demands of the biodiesel process are divided by energy content of the biodiesel, glycerol and K-fertiliser. For tallow biodiesel this yielded a net energy value of 38.6% of gross energy. The same method generated a net energy value of 67% for UCO biodiesel. More importantly the recommended method (allocation by energy content) generated a value of 54% greenhouse gas (GHG) emission savings for tallow and a value of 69% for UCO. Plants commencing after 2017, need to have a 60% GHG emission savings, to be considered sustainable. Thus a facility treating both feedstocks would need to treat a maximum of 60% tallow to be considered sustainable after 2017.
A great number of daylighting research activities including investigations of innovative daylighting systems, lighting controls, and development of daylighting design tools are being conducted in Australia, North America, and Europe. There is a strong need for coordination and sharing of the experience from these activities, and for transformation of the achievements into practical building design guidance. International collaboration is necessary for the establishment of procedures for the characterization and evaluation of daylighting and lighting control system performance under the very diverse nature of sky conditions throughout the world, and it was on this basis that IEA Task 21 started in 1995. Task 21 is a comprehensive collaborative research effort, involving more than 40 institutions from 16 IEA countries, under the Solar Heating & Cooling Programme of the International Energy Agency. The paper reports on the work of this huge international daylighting Task, with only 12 months to go of its four-year duration, describing how the work hopefully will influence on future building design.
Comparison of two techniques for wind speed forecasting in the South Coast of the state of Oaxaca, Mexico is presented in this paper. The Autoregressive Integrated Moving Average (ARIMA) and the Artificial Neural Networks (ANN) methods are applied to a time series conformed by 7 years of wind speed measurements. Six years were used in the formulation of the models and the last year was used to validate and compare the effectiveness of the generated prediction by the techniques mentioned above. Seasonal ARIMA models present a better sensitivity to the adjustment and prediction of the wind speed for this case in particular. Nevertheless, it was shown both developed models can be used to predict in a reasonable way, the monthly electricity production of the wind power stations in La Venta, Oaxaca, Mexico to support the operators of the Electric Utility Control Centre.
“Solar Chemistry and Solar Materials Research” is one important task of the “Solar Energy Association North Rhine–Westphalia, Germany”. Numerous individual projects have been carried out which address the construction and operation of a high-flux solar furnace, solar chemical engineering, and solar materials research. Almost 10 years of research and development have led to significant progress. This paper reviews the scope of work in solar chemistry and summarizes the results. The authors present perspectives for commercialization and address open questions and needs for further research and development.
The UNESCO Engineering Education and Training Programme is currently focusing its priorities on training of engineering students (although much of the output is suitable for advanced undergraduates) and working engineers requiring retraining or updating. To meet the needs especially for educational materials for developing countries and for distance-learning purposes, a multi-media “Learning Package” is in preparation which consists of a textbook, multi-media products and software for self-training and distance learning. It is intended to train students in the field of renewable energies with some dozen packages in preparation or for which half of the textbooks have already been published.
Energy is a vital input for economic and social development of any country. With increasing industrial and agricultural activities in the country, the demand for energy is also rising. Solar, wind and biomass are accepted as dependable and widely available renewable sources of energy. Development of an energy model will help in the proper allocation of these renewables in meeting the future demand of energy in India. The present work deals with the development of an Optimal Renewable Energy Model (OREM) for the effective utilisation of renewable energy sources in India for the year-2020-21. The objective of the Optimal Renewable Energy Model (OREM) was minimising cost/efficiency ratio based on social acceptance, reliability, demand and potential constraints. The OREM model allocated renewable energy sources for different end-uses such as lighting, cooking, pumping, heating, cooling and transportation for the year 2020-21.
A preliminary solar–hydrogen energy system for the United Arab Emirates (UAE) has been proposed to bridge the gap between oil and natural gas demand and supply in the 21st century, and to meet the country's share in the energy market. In our study, we quantitatively consider the benefits of such an energy system on the overall energy situation in the UAE. The variables considered include population, energy demand, energy production, income from sales of fossil fuels and hydrogen energy, photovoltaics area, and total land area required for installing such a system. Our study indicated that the UAE would fail to meet its share in the oil market demand by the year 2015, while in the case of natural gas it will be by the year 2042. In order to maintain its share in the world energy market, we propose that hydrogen be gradually introduced to meet the demand. The income generated by hydrogen energy would account for 90% of the nation's total income if such a system were utilized. Our analysis could be greatly influenced by several factors such as future government projects related to fossil fuel production and increasing diversification in the economy of the country.
In most developing countries more than 25% of total energy use comes from biofuels. In Ghana, the figure is between 70–80%. Bioenergy is mainly used for cooking and heating, and is also important in rural or cottage industries. As a developing country, Ghana's economic growth remains coupled to the availability and supply of energy. About 29% of this energy is obtained through hydropower and imported petroleum. The two hydropower installations generate about 1102 MW annually mainly for domestic and industrial uses. At the current 3.0% average annual population growth rate, a population of about 35 million is expected by 2025. Coupled with the country's efforts to promote industrialisation, future energy demand is expected to increase severalfold. This paper provides an overview of Ghana's current energy situation and discusses the role of bioenergy in the future energy demand of the country. The paper concludes with a recommendation for a major shift in energy policy to accommodate the conversion of biofuels into versatile energy carriers in a decentralised system to meet the energy requirements of the people and to provide a basis for rural development and employment.