Use Of Solar Thermal Energy Research Articles

Use of solar thermal energy in the hydrodistillation of essential oil

There has been rising demand in recent years for environment friendly technologies which has spurred interest in sustainable energy solutions. The use of solar radiation in place of fossil fuel-derived thermal energy to extract essential oils in decentralized manner is one such potentially attractive proposition. The present work reports such a study for hydrodistillation of essential oil from fresh orange peels. The distillation was carried out in the absorber tube of a square parabolic trough concentrator of 1.3 m2 collector aperture area. 400–500 g of fresh peels was processed per batch and the limonene content in the crude oil was in the range of 86% to 90% while the yield of the oil varied from 0.49% to 2.16% (w/w). The volume of distillate was found to correlate nicely with the average absorber tube temperature over the duration of the experiment and the maximum hydrodistillation efficiency was computed to be 8.37%. The yield of oil also showed a good correlation with the absorber tube temperature. The tube temperature, in turn, was controlled by the beam radiation, ambient temperature and wind speed.

Solar industrial process heating in Australia – Past and current status

Thirty years ago in Australia, there was a significant research, development and demonstration programme in solar industrial process heating (SIPH). This activity was led principally by the Commonwealth Science and Industrial Research Organisation, the country’s main scientific research body. Other state government bodies also funded demonstration projects. Today, there is very little SIPH activity at any level in Australia. The contrast with the progress in other renewable energy technologies like wind and solar photovoltaic systems is striking. While the implementation of these technologies has progressed, SIPH has gone backwards. If Australia is to decarbonise its economy at the rate required, a massive deployment of solar thermal technology in those industries which use large quantities of low temperature hot water is also required. Recent developments nationally and internationally may rekindle new applications of solar thermal energy use by industry. This paper reviews the past achievements in SIPH in Australia and describes the lessons learned in order to better prepare for any new wave of SIPH activity.

Long-term performance calculations based on steady-state efficiency test results: Analysis of optical effects affecting beam, diffuse and reflected radiation

There are a growing number of commercially available solar thermal collector types: flat plates, evacuated tubes with and without back reflectors and different tubular spacing or low concentration collectors, using different types of concentrating optics. These different concepts and designs all compete to be more efficient or simply cheaper, easier to operate, etc. at ever higher temperatures, and to extend the use of solar thermal energy in other applications beyond the most common water heating purposes. In view of the proper dimensioning of solar thermal systems and proper comparison of different collector technologies, for a given application, there is a growing need for existing and future simulation tools to be as accurate as possible in the treatment of these different collector types. Collector heat losses are usually considered to be well determined, under variable operating conditions, through the use of the heat loss coefficients provided by efficiency curve parameters. Yet, the traditional approach to the optical efficiency fails to describe accurately the optical effects affecting the amount of radiation which actually reaches the absorber. This paper develops a systematic approach to the proper handling of incident solar radiation, folding that with the information available from tests for determination of collector efficiency curve (steady-state) and the way the optics of different collector types uses incident solar radiation and transforms it into useful heat.

A Novel Solar-Hybrid Gas Turbine Combined Cycle With Inherent CO2 Separation Using Chemical-Looping Combustion by Solar Heat Source

In this paper we propose a novel CO2-recovering hybrid solar-fossil combined cycle with the integration of methane-fueled chemical-looping combustion, and investigate the system with the aid of the Energy-Utilization Diagram (EUD). Chemical-looping combustion (CLC) consists of two successive reactions: first, methane fuel is oxidized by metal oxide(NiO)as an oxygen carrier (reduction of metal oxide); and second, the reduced metal (Ni) is successively oxidized by combustion air (the oxidation of metal). The oxidation of methane with NiO requires a relative low-grade thermal energy at 300°C-500°C. Then concentrated solar thermal energy at approximately 450°C-550°C can be utilized to provide the process heat for this reaction. By coupling solar thermal energy with methane-fueled chemical-looping combustion, the energy level of solar thermal energy at around 450°C-550°C can be upgraded to the chemical energy of solid fuel Ni for better utilization of solar energy to generate electricity. The synergistic integration of solar thermal energy and chemical-looping combustion could make the exergy efficiency and the net solar-to-electric efficiency of the solar hybrid system more than 60% and 30%, respectively, at a turbine inlet temperature (TIT) of 1200°C. At the same time, this new system has an extremely important advantage of directly suppressing the environmental impact due to lack of energy penalty for CO2 recovery. Approximately 9–15 percentage points higher efficiency can be achieved compared to the conventional natural gas-fired combined cycle with CO2 separation. The results obtained here are promising and indicate that this novel solar hybrid combined cycle offers the new possibility of CO2 mitigation using both green energy and fossil fuels. These results also provide a new approach for highly efficient use of solar thermal energy to generate electricity.

97/01251 A CO 2-capturing hybrid power-generation system with highly efficient use of solar thermal energy

97/01251 A CO 2-capturing hybrid power-generation system with highly efficient use of solar thermal energy

A CO 2-capturing hybrid power-generation system with highly efficient use of solar thermal energy

Characteristics have been investigated for the proposed system. Saturated steam is produced at a relatively low temperature and is used as the working fluid for a methane-fired gas-turbine system. The solar thermal utilization efficiency is considerably higher than that for conventional solar thermal power plants in which superheated steam near 670 K is used. The proposed hybrid system recovers generated CO 2 during combustion with oxygen. Characteristics of the system with 10,000 m 2 collector area were estimated on the basis of a computer simulation model. The net generated power was 1.55 MW, the capacity factor 21.5% and the total exergetic efficiency 20.9% when the temperature of the saturated steam is 496 K. Based on the consumed fuel, the net thermal system efficiency is 63.7%.

Energy, cost, and carbon dioxide optimization of disaggregated, regional energy-supply systems

Energy conservation and greenhouse warming mitigation can be supported by cogeneration of heat and power and by heat recovery via heat exchangers and via the upgrading of environmental and waste heat by heat pumps. Fuel switching, the use of solar thermal energy, and the removal and disposal of CO 2 may complement these measures. In order to determine the optimum combination of these options with conventional energy-conversion technologies for regional energy-supply systems with disaggregated, fluctuating energy-exergy demand profiles, we have developed stochastic and quasi-dynamic vector-optimization models which can be used as computerized planning tools. The application of the stochastic optimization model ECCO to a south German model city shows that the primary energy input into the system and the CO 2 emissions may be reduced by about 25% and 30%, respectively. These figures change as the average ambient temperature deviates from 10 °C. The quasi-dynamic optimization model ECCO-Solar, applied to an army facility which served as a pilot project with well documented energy and weather data, yields savings of primary energy and CO 2 emissions which vary between 20% and 50%, depending upon the scenario. Both models show that the optimum combination of technologies depends very sensitively on the details of the demand situation. Computing the costs and reducing them interactively, one finds that nearly all of the considered energy conservation and emission reduction strategies will become economical only at energy prices which are considerably higher than the present ones.

A multiobjective programming approach to energy resource allocation problems

The optimal allocation of energy resources to various energy end uses is an important strategy for bridging the energy supply and demand gap in India. It has been recognized that the allocation should be guided by multiple criteria. A multiobjective programming model for such an allocation process is presented in the paper. The normative model has been applied for the households sector of Madras city. The model is solved using non pre-emptive goal programming. Variations in the original model have been made to build alternative scenarios. The results of the original model and the alternative scenarios indicate that the use of solar thermal energy, natural gas, LPG, fuelwood, kerosene and lignite should be promoted for cooking, and the use of grid electricity and diesel, should be promoted for meeting water pumping demands. They favour the use of electricity generated from diesel for lighting, and the use of solar photovoltaics for meeting the electricity demands of household appliances. The results also indicate that grid electricity and electricity generated from fuelwood should be promoted to meet the demands of all the four household end uses, and point to the need for more research into solar photovoltaics, which may become competitive for meeting household demands in the future.

System Performance of Solar Thermal High Temperature Utilization Systems Constructed in Japan

Two solar thermal electric power plants and a solar total energy experimental facility were constructed for the effective use of solar thermal energy and then operated for about three years. Their development for commercial use has been completed because of low system performance and the poor solar conditions in Japan. Under these circumstances, for future development of these systems, we believe it is most important to improve system performance under poor solar conditions such as those experienced in Japan. Therefore, we consider here a method to improve system availability based on the operating characteristics of the system. It is shown that under poor solar conditions, it is important to collect not only high temperature heat but also low temperature heat, according to the solar condition, and to use the collected heat for either heat energy supply or electricity generation.

Dish Concentrators for Solar Thermal Energy

A wide variety of point-focusing concentrators are under consideration for solar thermal energy use. They are briefly reviewed in this paper. These concentrators differ in such characteristics as optical configuration and materials, structure for support of the optical elements and receiver, mount, foundation, drive, and controls. Point-focusing concentrators require good optical efficiency and, especially for high-temperature applications, high geometric concentration ratios. Most important are low cost, as installed, and low lifetime cost. Critical cost contributors for quantity production are the cost of materials and the cost of installation labor. Field testing and performance measurements of concentrators, with receivers and controls, are badly needed.