scholarly journals Solar Rankine Engines: Examples and Projected Costs

Author(s):  
R. E. Barber

Solar heat can be converted into shaft power by use of the Organic Rankine Cycle Engine (ORCE). The efficiency of the ORCE to convert the solar heat to shaft power varies from 7 or 8 percent for an ORCE heated by low temperature flat plate collectors at 200 F, to near 15 percent when heated by intermediate temperature collectors (300 F), and up to 25 percent with high temperature concentrating collectors (600 F). Barber-Nichols designed, built, and tested its first solar heated ORCE in 1973, which produced three tons of air conditioning. Since that time, the three-ton unit has reached its fourth iteration on the development path to production; a 77-ton water chiller was installed at LASL; two ORCE drives for 100-ton water chillers were delivered to Honeywell; seven 25-ton water Chillers were delivered to DOE demonstration sites; and a 25-hp ORCE for irrigation pumping was installed in Willard, N.M. Photographs, design details, and the measured performance of these units are presented herein as examples. The cost of solar power systems using an ORCE is also presented which shows that for the current $150 to $200/m2 cost of cencentrating collectors, the system cost would be in excess of $2500/kw peak. The ORCE is approximately 25 percent of this cost or $600/kw. Consequently, while reductions in the cost and improvements in the performance of the ORCE can and should be made in the development process, the cost competitiveness of a solar power system is largely dependent on developing low cost concentrating collectors which can be sold for 1/2 to 1/3 of today’s price.

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Fayrouz El hamdani ◽  
Sébastien Vaudreuil ◽  
Souad Abderafi ◽  
Tijani Bounahmidi

Abstract Concentrating solar power (CSP) technology is one of the promising options to generate green energy. However, the cost of kWhe produced is relatively high compared with fossil resources and can be reduced by integrating a cogeneration system exploiting waste energy. In this study, a technico-economic evaluation of a 1 MWe CSP plant with a condensation heat (85 °C) is investigated. The temperature constraint is set to meet the thermal separation needs of the draw solution of a forward osmosis desalination process. The purpose of this study focuses on the factors involved in reducing the cost per kWhe, which are the selection of the organic fluid used in the organic Rankine cycle and the appropriate choice of the solar multiple (SM) according to the appropriate storage hours (SH) maximizing the CSP thermal efficiency. The performance of different organic fluids was compared, based on the calculation of the thermodynamic cycle efficiency. The cyclopentane was retained for its reduced cost. Operating with this fluid, a sensitivity analysis was realized to test the effect of the solar multiple and storage hours on the power plant. It allows us to conclude that different appropriate combination between storage hours and solar multiple can be chosen, for the needs of our project, we opt for 8 h and 1.85, respectively. Thus, in this case, the cost of kWh was found to be 23.95¢.


Author(s):  
Vahab Hassani ◽  
Henry W. Price

Abstract A number of factors are creating an increased market potential for small trough power technology. These include the need for distributed power systems for rural communities worldwide, the need to generate more electricity by non-combustion renewable processes, the need for sustainable power for economic growth in developing countries, and the deregulation and privatization of the electrical generation sector worldwide. Parabolic trough collector technology has been used in large central station power plants. Organic Rankine cycle (ORC) air-cooled modular power units have been successfully applied for large and small-scale geothermal power plants, with over 600 MW of capacity, during the same period. The merging of these two technologies to produce distributed modular power plants in the 200 kW to 10 MW range offers a new application for both technologies. It is our objective in this paper to introduce a modular trough power plant (MTPP) and discuss its performance and the cost of electricity generation from such system.


Author(s):  
Jian Song ◽  
Chun-wei Gu

Energy shortage and environmental deterioration are two crucial issues that the developing world has to face. In order to solve these problems, conversion of low grade energy is attracting broad attention. Among all of the existing technologies, Organic Rankine Cycle (ORC) has been proven to be one of the most effective methods for the utilization of low grade heat sources. Turbine is a key component in ORC system and it plays an important role in system performance. Traditional turbine expanders, the axial flow turbine and the radial inflow turbine are typically selected in large scale ORC systems. However, in small and micro scale systems, traditional turbine expanders are not suitable due to large flow loss and high rotation speed. In this case, Tesla turbine allows a low-cost and reliable design for the organic expander that could be an attractive option for small scale ORC systems. A 1-D model of Tesla turbine is presented in this paper, which mainly focuses on the flow characteristics and the momentum transfer. This study improves the 1-D model, taking the nozzle limit expansion ratio into consideration, which is related to the installation angle of the nozzle and the specific heat ratio of the working fluid. The improved model is used to analyze Tesla turbine performance and predict turbine efficiency. Thermodynamic analysis is conducted for a small scale ORC system. The simulation results reveal that the ORC system can generate a considerable net power output. Therefore, Tesla turbine can be regarded as a potential choice to be applied in small scale ORC systems.


Author(s):  
Matthias Mitterhofer ◽  
Matthew Orosz

Small scale solar thermal systems are increasingly investigated in the context of decentralized energy supply, due to favorable costs of thermal energy storage (TES) in comparison with battery storage for otherwise economical PV generation. The present study provides the computational framework and results of a one year simulation of a low-cost pilot 3kWel micro-Concentrated Solar Power (micro-CSP) plant with TES. The modeling approach is based on a dynamic representation of the solar thermal loop and a steady state model of the Organic Rankine Cycle (ORC), and is validated to experimental data from a test site (Eckerd College, St. Petersburg, Florida). The simulation results predict an annual net electricity generation of 4.08 MWh/a. Based on the simulation, optimization studies focusing on the Organic Rankine Cycle (ORC) converter of the system are presented, including a control strategy allowing for a variable pinch point in the condenser that offers an annual improvement of 14.0% in comparison to a constant condensation pinch point. Absolute electricity output is increased to 4.65 MWh/a. Improvements are due to better matching to expander performance and lower condenser fan power because of higher pinch points. A method, incorporating this control strategy, is developed to economically optimize the ORC components. The process allows for optimization of the ORC subsystem in an arbitrary environment, e.g. as part of a micro-grid to minimize Levelized electricity costs (LEC). The air-cooled condenser is identified as the driving component for the ORC optimization as its influence on overall costs and performance is of major significance. Application of the optimization process to various locations in Africa illustrates economic benefits of the system in comparison to diesel generation.


2013 ◽  
Vol 8 (suppl 1) ◽  
pp. i34-i41 ◽  
Author(s):  
E. Georges ◽  
S. Declaye ◽  
O. Dumont ◽  
S. Quoilin ◽  
V. Lemort

Author(s):  
Henry Price ◽  
Mark Mehos ◽  
Chuck Kutscher ◽  
Nate Blair

Solar energy is the largest energy resource on the planet. Unfortunately, it is largely untapped at present, in part because sunlight is a very diffuse energy source. Concentrating solar power (CSP) systems use low cost reflectors to concentrate the sun’s energy to allow it to be used more effectively. Concentrating solar power systems are also well suited for large solar power plants that can be connected into the existing utility infrastructure. These two facts mean that CSP systems can be used to make a meaningful difference in energy supply in a relatively short period. CSP plants are best suited for the arid climates in the Southwestern United States, Northern Mexico, and many desert regions around the globe. A recent Western Governors’ Association siting study [1] found that the solar potential in the U.S. Southwest is at least 4 times the total U.S. electric demand even after eliminating urban areas, environmentally sensitive areas, and all regions with a ground slope greater than 1%.While it is currently not practical to power the whole county from the desert southwest, only a small portion of this area is needed to make a substantial contribution to future U.S. electric needs. Many of the best sites are near existing high-voltage transmission lines and close to major power load centers in the Southwest (Los Angeles, Las Vegas, and Phoenix). In addition, the power provided by CSP technologies has strong coincidence with peak electric demand, especially in the Southwest where peak demand corresponds in large part to air conditioning loads. Parabolic troughs currently represent the most cost-effective CSP technology for developing large utility-scale solar electric power systems. These systems are also one of the most mature solar technologies, with commercial utility-scale plants that have been operating for over 20 years. In addition, substantial improvements have been made to the technology in recent years including improved efficiency and the addition of thermal energy storage. The main issue for parabolic trough technology is that the cost of electricity is still higher than the cost of electricity from conventional natural gas-fired power plants. Although higher natural gas prices are helping to substantially reduce the difference between the cost of electricity from solar and natural gas plants, in the near-term increased incentives such as the 30% Investment Tax Credit (ITC) are needed to make CSP technology approach competitiveness with natural gas power on a financial basis. In the longer term, additional reductions in the cost of the technology will be necessary. This paper looks at the near-term potential for parabolic trough technology to compete with conventional fossil power resources in the firm, intermediate load power market and at the longer term potential to compete in the baseload power market. The paper will consider the potential impact of a reduced carbon emissions future.


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