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This paper presents a potential of a solar organic Rankine cycle (ORC) with evacuated-tube solar collectors with of 0.81, of 2.551 W/m2K as heat source for generating electricity under the climate of Thailand. The power output of the ORC power plant was 280 kW and the ORC working fluid was R245fa. The weather conditions of Chiang Mai (18.783 oN, 98.983 oE), Ubon Ratchathani (15.233 oN, 104.783 oE), Hat Yai (6.91 oN, 100.43 oE) and Bangkok (13.66 oN, 100.56 oE) represented the northern, northeastern, southern and central part of Thailand, respectively were taken as the input data of the calculations. It could be found that at Chiang Mai, the levelized electricity cost was lowest which was 0.37 USD/kWh and the annual solar-to-electricity efficiency was 4.44%. At Bangkok and Ubon Ratchathani, the levelized electricity costs were slightly higher than that of Chiang Mai. At Hat Yai, the levelized electricity cost was found to be highest which was 0.43 USD/kWh.
Key words: Solar organic rankine cycle; Solar collector; Electrical power generation; Performance analysis; Levelized electricity cost
Thawonngamyingsakul, C., & Kiatsiriroat, T. (2012). Potential of a Solar Organic Rankine Cycle with Evacuated-Tube Solar Collectors as Heat Source for Power Generation in Thailand. Energy Science and Technology, 4(2),-0. Available from: URL: http://www.cscanada.net/index.php/est/article/view/10.3968/j.est.1923847920120402.558
DOI: http://dx.doi.org/10.3968/j.est.1923847920120402.558
INTRODUCTION
World net electricity generation increased from 13.29×1012 kWh in 2001 to 18×1012 kWh in 2006, with a growth rate of 6.3 percent per year (EIA, 2004; EIA, 2009). Coal retains the largest market share of the world electricity generation (roughly 40 percent) while natural gas and renewables retained the market share at roughly 21 and 19 percent, respectively (EIA, 2006). The coal and natural gas power plants have caused many environmental problems such as global warming, ozone layer destruction and atmospheric pollution. Gagnon et al. (2002) found that the greenhouse gas emissions from coal and natural gas power plant were 1050 and 443 g of carbon dioxide equivalent per kWh (gCO2e/kWh), respectively. A solution for reduction of environment problems is the use of renewable energy such as solar energy, wind energy, geothermal energy and biomass as heat sources for electricity generation. The greenhouse gas emissions of renewable energy power plants were less than 41 gCO2e/kWh (Pehnt, 2006; Fthenskis et al., 2008). At present, concentrating solar power (CSP) technology can be exploited through three different systems, i.e. the parabolic trough system, the tower system and the dish/Stirling engine system. All the CSP technologies will be appropriate for countries having high direct normal solar radiation. There were some reports showed that the average direct normal solar radiation values for power generation should be above 1500 kWh/m2-year (IEA, 2003; Bravo et al., 2007; Purohit & Purohit, 2010). The investment and electricity generation costs for CSP technologies are also shown in Table 1 (IEA, 2003). For Thailand (Department of Alternative Energy Development and Efficiency & Ministry of Energy, 2006), the annual direct normal solar radiation was in a range of 1350-1400 kWh/m2-year which was rather low for the CSP technologies. Ketjoy and Rakwichian (2006) studied techno-economic feasibility of a solar parabolic technology for power generation in Thailand. The required maximum electrical power was 800 kW. It was found that the cost of energy (COE) was 25.52 Baht/kWh or 0.85 USD/kWh (30 Baht is about 1 USD). Wibulswas (1998) and Vorayos et al. (2009) reported the diffuse component of the solar radiation in Thailand was quite high since the country is in the monsoon area and it was about 50% of the total solar radiation. A solution for this problem (low annual direct normal solar radiation) was the use of evacuated-tube solar collectors instead of solar concentrators as a heat source for running organic Rankine cycle (ORC) to generate electrical power. The ORC works similar to the Rankine steam power plant but it uses an organic working fluid instead of water. There are some reports on the ORC with different low temperature heat sources such as waste heat (Hung, 2001), solar thermal (Achary et al., 1983; Jing et al., 2010), biomass (Drescher & Bruggemann, 2007) and geothermal (Heberle & Bruggemann, 2010), etc. Wang et al. (2010) studied performance analysis of a low-temperature solar organic Rankine cycle system utilizing R245fa with flat-plate collector as heat source. The average overall efficiency was 0.88%. Wei et al. (2007) also studied performance analysis and optimization of an ORC system using R245fa as working fluid.
Key words: Solar organic rankine cycle; Solar collector; Electrical power generation; Performance analysis; Levelized electricity cost
Thawonngamyingsakul, C., & Kiatsiriroat, T. (2012). Potential of a Solar Organic Rankine Cycle with Evacuated-Tube Solar Collectors as Heat Source for Power Generation in Thailand. Energy Science and Technology, 4(2),
DOI: http://dx.doi.org/10.3968/j.est.1923847920120402.558
INTRODUCTION
World net electricity generation increased from 13.29×1012 kWh in 2001 to 18×1012 kWh in 2006, with a growth rate of 6.3 percent per year (EIA, 2004; EIA, 2009). Coal retains the largest market share of the world electricity generation (roughly 40 percent) while natural gas and renewables retained the market share at roughly 21 and 19 percent, respectively (EIA, 2006). The coal and natural gas power plants have caused many environmental problems such as global warming, ozone layer destruction and atmospheric pollution. Gagnon et al. (2002) found that the greenhouse gas emissions from coal and natural gas power plant were 1050 and 443 g of carbon dioxide equivalent per kWh (gCO2e/kWh), respectively. A solution for reduction of environment problems is the use of renewable energy such as solar energy, wind energy, geothermal energy and biomass as heat sources for electricity generation. The greenhouse gas emissions of renewable energy power plants were less than 41 gCO2e/kWh (Pehnt, 2006; Fthenskis et al., 2008). At present, concentrating solar power (CSP) technology can be exploited through three different systems, i.e. the parabolic trough system, the tower system and the dish/Stirling engine system. All the CSP technologies will be appropriate for countries having high direct normal solar radiation. There were some reports showed that the average direct normal solar radiation values for power generation should be above 1500 kWh/m2-year (IEA, 2003; Bravo et al., 2007; Purohit & Purohit, 2010). The investment and electricity generation costs for CSP technologies are also shown in Table 1 (IEA, 2003). For Thailand (Department of Alternative Energy Development and Efficiency & Ministry of Energy, 2006), the annual direct normal solar radiation was in a range of 1350-1400 kWh/m2-year which was rather low for the CSP technologies. Ketjoy and Rakwichian (2006) studied techno-economic feasibility of a solar parabolic technology for power generation in Thailand. The required maximum electrical power was 800 kW. It was found that the cost of energy (COE) was 25.52 Baht/kWh or 0.85 USD/kWh (30 Baht is about 1 USD). Wibulswas (1998) and Vorayos et al. (2009) reported the diffuse component of the solar radiation in Thailand was quite high since the country is in the monsoon area and it was about 50% of the total solar radiation. A solution for this problem (low annual direct normal solar radiation) was the use of evacuated-tube solar collectors instead of solar concentrators as a heat source for running organic Rankine cycle (ORC) to generate electrical power. The ORC works similar to the Rankine steam power plant but it uses an organic working fluid instead of water. There are some reports on the ORC with different low temperature heat sources such as waste heat (Hung, 2001), solar thermal (Achary et al., 1983; Jing et al., 2010), biomass (Drescher & Bruggemann, 2007) and geothermal (Heberle & Bruggemann, 2010), etc. Wang et al. (2010) studied performance analysis of a low-temperature solar organic Rankine cycle system utilizing R245fa with flat-plate collector as heat source. The average overall efficiency was 0.88%. Wei et al. (2007) also studied performance analysis and optimization of an ORC system using R245fa as working fluid.