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[en] The North Africa climate is dry and warm with annual mean temperature from 15 degree centigrade to 25 degree centigrade, with a temperature difference of 20 degree centigrade between the coldest and warmest month. Heating is needed during the short winter and there is a large cooling demand during the long summer. Since the undisturbed ground temperature is equal to the annual mean air temperature, the ground is warmer than the air during the winter and colder than air during summer. This is what is required for the direct use of the ground for heating and cooling. In such systems, ground coupled heating and cooling systems, and also in storage systems, Underground Thermal Energy Storage (UTES), some kind of underground duct (PIPE) system is used to inject or extract heat from the ground. Thermal energy is then stored and recovered by heating and cooling of the ground, while the ducts are the heat exchangers with the system. The duct system could be placed horizontally or vertically (e.g. in boreholes) in the ground. In many cases heat pumps or cooling machines are included in the systems but in favourable cases, such as in the North African climate, the ground can be used directly for heating and cooling. then, only a circulation pump is used to pump water through the underground duct system with high efficiencies. Such systems can also be used for thermal energy storage, during shorter periods (diurnal) or even between the seasons. In September 2005 Sebha University and Luleu University of Technology started a Libyan Swedish collaboration to develop and implement these systems for the North African climate. Sweden has considerable experience in ground coupled systems, theoretically and practically, and there are presently more than 300.000 systems in operation in Sweden, mainly for heating. Most of these are small-scale heating systems for singe-family houses but during the last decade several hundred large-scale systems have been built for heating and cooling of commercial buildings. The ongoing collaboration will consider local traditions and systems for cooling and the aim is to combine such old methods with ground coupled heating and cooling systems. This PhD work includes simulation, testing, and the design of this system for Libya. Planned ongoing work is outlined in this paper.(Author)
[en] About 20 years ago, we decided to make our house. Being working on the utilization of solar energy and with the objective of saving maximum conventional fuel and some family budget, we dicided to make use of maximum this free and clean fuel. After buying the land with proper orientation, we installed different cheap devices and left the proper provision for another devices to installed in future. At present we solar energy mainly for cooking, water heating for bath and dish washing, drying clothes/fruits/vegetables, purification (pasteurization) of water. In addition. we also use solar cells for some electrical devices like solar radio, solar lamp for emergency, charging batteries and mobile phone etc. For our family of five persons, having 3 coloured TV, 2 computers using many hours of Internet, without any use of fuel other than electricity and sun, our electricity consumption is of the order of 270 (dry/summer)-350 (wet/rainy) kWh/month, depending on the season (US$16-21/month). This is roughly 40-50% of the electricity consumed by my other colleagues who do not use solar energy. With this saving, the initial cost of solar devices (US$1200-1400) is already recovered. In this presentation, construction and results of working of these solar thermal, electrical devices and other energy saving means at our house are mentioned.(Author)
[en] One of the attractions of developing bioenergy systems is the potential for job creation and economic development of rural economies. This paper seeks to quantify the expected employment impacts of individual bioenergy developments. The assessment includes agricultural labour growing energy crops for SRC and miscanthus options, transport and processing of the feedstock, staffing at the thermal conversion plant, employment within the equipment supply chain and the induced employment impact. Power only bioenergy systems are shown to typically create 1.27 man years of employment per GWh electricity produced, regardless of technology or scale of implementation. CHP systems can create more than 2 man years of employment per GWh electricity produced, although most of this enhanced economic impact can be attributed to the fact that a comparative analysis per unit of electricity produced ignores the heat output of the system. (author)
[en] This special issue on Solar energy and nano materials for clean energy development is composed of selected, full-length versions of papers presented during the international Solar 09 conference that was held in the fascinating historical city of Luxon. The conference gathered scientists from 26 countries, to discuss outstanding research on a multitude of topics and disciplines. As was pointed out by Professor Paul Barbara from the University of Texas in Austin at the opening session of the conference, this medium-sized conference offered the unique opportunity to learn and exchange scientific issues from distinct disciplines that have one main thing in common, solar photons. This exceptional opportunity to learn about other fields of research not only required particular didactic skills form the speakers, but also demanded special attention and openness from the audience.
[en] Geothermal binary power plants that use low-temperature heat sources have gained increasing interest in the recent years due to political efforts to reduce greenhouse gas emissions and the consumption of finite energy resources. The construction of such plants requires large amounts of energy and material. Hence, the question arises if geothermal binary power plants are also environmentally promising from a cradle-to-grave point of view. In this context, a comprehensive Life Cycle Analysis (LCA) on geothermal power production from EGS (enhanced geothermal systems) low-temperature reservoirs is performed. The results of the analysis show that the environmental impacts are very much influenced by the geological conditions that can be obtained at a specific site. At sites with (above-) average geological conditions, geothermal binary power generation can significantly contribute to more sustainable power supply. At sites with less favorable conditions, only certain plant designs can make up for the energy and material input to lock up the geothermal reservoir by the provided energy. The main aspects of environmentally sound plants are enhancement of the reservoir productivity, reliable design of the deep wells and an efficient utilization of the geothermal fluid for net power and district heat production.
[en] A solar-assisted ejector cooling/heating system (SACH) was developed in this study. The SACH combines a pump-less ejector cooling system (ECS) with an inverter-type heat pump (R22) and is able to provide a stable capacity for space cooling. The ECS is driven by solar heat and is used to cool the condenser of the R22 heat pump to increase its COP and reduce the energy consumption of the compressor by regulating the rotational speed of the compressor through a control system. In a complete SACH system test run at outdoor temperature 35 deg. C, indoor temperature 25 deg. C and compressor speed 20-80 Hz, and the ECS operating at generator temperature 90 deg. C and condensing temperature 37 deg. C, the corresponding condensing temperature of the heat pump in the SACH is 24.5-42 deg. C, cooling capacity 1.02-2.44 kW, input power 0.20-0.98 kW, and cooling COPc 5.11-2.50. This indicates that the use of ECS in SACH can effectively reduce the condensing temperature of the heat pump by 12.6-7.3 deg. C and reduce the power consumption by 81.2-34.5%. The SACH can also supply heat from the heat pump. At ambient temperature from 5 deg. C to 35 deg. C, the heating COPh is in the range 2.0-3.3.
[en] Due to rising fuel costs, the substantial price for CO2 emissions and decreasing wind power costs, wind power might become the least expensive source of power for an increasing number of power systems. This poses the questions of how wind power might change optimal investments in other forms of power production and what kind of means could be used to increase power system flexibility in order to incorporate the variable power production from wind power in a cost-effective manner. We have analysed possible effects using an investment model that combines heat and power production and simulates electric vehicles. The model runs in an hourly time scale in order to accommodate the impact of variable power production from wind power. Electric vehicles store electricity for later use and can thus serve to increase the flexibility of the power system. Flexibility can also be upgraded by using heat storages with heat from heat pumps, electric heat boilers and combined heat and power (CHP) plants. Results show that there is great potential for additional power system flexibility in the production and use of heat. (author)
[en] This paper develops a model to explain the 'energy paradox,' the inclination of households and firms to require very high internal rates of return in order to make energy-saving investments. The model abstracts from many features of such investments to focus on their irreversibility, the uncertainty of their future payoff streams, and the investor's anticipation of future technological advance. In this setting, the decision to invest in energy-saving technology can be delayed, providing option value. In addition, delay allows the potential investor to cash in on future experience-curve effects: With the passage of time, firms gain practical knowledge in producing and installing the energy-saving technology, enabling them to reduce the technology's up-front cost per unit of energy saved. We incorporate these fundamentals into a stochastic model where the investment's discounted benefits follow geometric Brownian motion. To demonstrate the model's capabilities, we generate simulation results for photovoltaic systems that highlight the experience-curve effect as a fundamental reason why households and firms delay making energy-saving investments until internal rates of return exceed values of 50% and higher, consistent with observations in the economics literature. We also explore altruistic motivations for energy conservation and the model's implications for both 'additionality' and the design of energy-conservation policy
[en] Development is the enlargement of people's choices. Optimal subsidy policy is intended to create the right incentives for each of the value chain participants. This paper contends that the interest subsidy offered by the Indian federal Ministry of New and Renewable Energy for solar thermal systems, through mainstream banking channels is superior in intent and outcome compared to the capital subsidy as currently offered for solar PV systems, routed through government controlled delivery channels. The interest subsidy enhances innovation, improves service delivery and expands the range of product available to consumers enjoying a wide range of endowments, thus leading to more inclusive development. The simple monopoly model developed by Atkinson [Atkinson AB. Capabilities, exclusion and the supply of goods. In: Basu K, Pattanaik P, Suzumura K, editor, Choice, Welfare and Development. Oxford University Press; 1995] is applied to the context of solar home systems to demonstrate price reduction and choice expansion in a liberalized market, facilitated by an interest subsidy scheme. (author)
[en] The potential energy curve (PEC) of HI(X1Σ+) molecule is studied using the complete active space self-consistent field method followed by the highly accurate valence internally contracted multireference configuration interaction approach at the correlation-consistent basis sets, aug-cc-pV6Z for H and aug-cc-pV5Z-pp for I atom. Using the PEC of HI(X1Σ+), the spectroscopic parameters of three isotopes, HI(X1Σ+), DI(X1Σ+) and TI(X1Σ+), are determined in the present work. For the HI(X1Σ+), the values of D0, De, Re, ωe, ωeχe, αe and Be are 3.1551 eV, 3.2958 eV, 0.16183 nm, 2290.60 cm−1, 40.0703 cm−1, 0.1699 cm−1 and 6.4373 cm−1, respectively; for the DI (X1Σ+), the values of D0, De, Re, ωe, ωeχe, αe and Be are 3.1965 eV, 3.2967 eV, 0.16183 nm, 1626.8 cm−1, 20.8581 cm−1, 0.0611 cm−1 and 3.2468 cm−1, respectively; for the TI (X1Σ+), the values of D0, De, Re, ωe, ωeχe, αe and Be are of 3.2144 eV, 3.2967 eV, 0.16183 nm, 1334.43 cm−1, 14.0765 cm−1, 0.0338 cm−1 and 2.1850 cm−1, respectively. These results accord well with the available experimental results. With the PEC of HI(X1Σ+) molecule obtained at present, a total of 19 vibrational states are predicted for the HI, 26 for the DI, and 32 for the TI, when the rotational quantum number J is equal to zero (J = 0). For each vibrational state, vibrational level G(v), inertial rotation constant Bv and centrifugal distortion constant Dv are determined when J = 0 for the first time, which are in excellent agreement with the experimental results. (atomic and molecular physics)