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Potential of solar energy utilization in the textile industry — a case study
Renewable Energy 23 (2001) 685–694 www.elsevier.nl/locate/renene
Potential of solar energy utilization in the textile industry — a case study Adel M. Abdel-Dayem a, M.A. Mohamad a
b,*
Mubarak City for Scientific Research, Informatics Research Institute, El-Dekheela, Alexandria, Egypt b NRC, Solar Energy Department, Tahrir Street, Dokki, Cairo, Egypt
Abstract There is high energy consumption in the industrial sector at low-temperature levels, and solar energy could save a considerable part of this energy. A feasibility study to obtain the potential of solar energy utilization in the textile industry is presented. Two categories were considered in this study. The first category is a preheat solar system that can feed the boiler with hot water. This system can be efficiently utilized in this case because it can operate under different conditions of flow rate and output temperature. The second category is to feed the process of textile dyeing that needs low temperatures (up to 85°C) directly with hot water. In this case, the collector area is limited by the available area in the factory. Economic comparison between the two categories was provided to determine the optimal system that can be used efficiently. The optimum design of the two systems was studied depending on the optimum collector area and flow rate. It was found that the second system is more economic and efficient than the first. The environmental impact of using such a system was studied for different air and water pollutants. Reduction of carbon dioxide emission was found to be the main advantage of using solar energy as a clean energy source. 2001 Elsevier Science Ltd. All rights reserved.
1. Introduction The textile industry is a case study in which solar energy can be practically utilized. Where lower temperatures are needed for the textile process-heat, solar energy can be efficiently used at this level. In this case a simple cheap control system is required to control the system operation. In addition, using the solar energy as an energy source can save a large amount of the energy consumed in this industry. A feasibility study was carried out for a textile factory (El-Shourbagy Textile
* Corresponding author. 0960-1481/01/$ - see front matter 2001 Elsevier Science Ltd. All rights reserved. PII: S 0 9 6 0 - 1 4 8 1 ( 0 0 ) 0 0 1 5 4 - 3
686
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
Nomenclature A cA cf CM c0 L M N OM qcol r rf hbackup
collector area, m2 collector price fuel price, (12 £E/GJ was considered) price of the storage tank, £E/kg fixed cost of collector system, £E life-cycle savings (payback), £E mass of the storage tank, kg lifetime of the collector, yr. (20 years was expected) annual charge for operation and maintenance of collector expressed as a fraction of capital cost (=2% was assumed) output energy of the collector, J real rate of return on alternative investments of comparable risk real fuel escalation rate boiler backup efficiency (75% was normally considered)
Factory, Cairo 30° N) to obtain the potential of solar energy in this field. The dyeing and drying of the textiles are the two processes that need a large amount of energy for heating in this industry. Where the hot water at 80°C is required for the dyeing process, the drying process needs steam to dry the wet textile. In this process, the textile is passed over a hot surface of a cylinder and the steam from a boiler heats the inside of the cylinder. Two solar systems were considered in this study. The first is a system that can feed the dyeing process directly with hot water and the other is a part-load system that can supply the boiler with hot water as a pre-heater. An economic comparison between the two systems was carried out based on the solar fraction (i.e. ratio of the solar system output to the load) and the system efficiency. The proposed two systems are shown in Fig. 1 and Fig. 2. The solar system in
Fig. 1.
Schematic diagram of the dyeing solar system.
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
687
Fig. 2. Schematic diagram of the pre-heat (part-load) solar system.
general consists of collector, storage tank, control, pipes and pump. In Fig. 2 the used steam in the drying process, which is about 50% of the total steam generated, is returned to the boiler while the total steam generated is about 20 ton/hr during 10 hours a day. On the other side the contaminated water that is used in the dyeing processes cannot be reused. The TRNSYS Program was used to design the two systems considered. The meteorological data such as the solar radiation and the ambient temperature, as well as the wind speed, were fitted from the monthly average values. The payback (lifecycle savings) and the solar fraction as well as the system efficiency were integrated along the year. Hence, the yearly average outputs were provided for each system.
2. Methodology The optimal system that was considered in this study has the maximum payback payment during the lifetime (20 years was assumed). That means this system is more efficient with relatively low principal cost. Some authors, as in [1] and [2], expected this method of optimization that is based on the life-cycle savings (payback investment) of the system. The life-cycle savings (L) are the difference between fuel savings and the cost of the capital, operation and maintenance ([2]), L⫽qcol·Cf,l⫺Ccap(c0⫹cA·A⫹cM·M) Cf,l⫽
冋 冋 册册
cf(1+rf) 1+rf 1⫺ hbackup(r−rf) 1+r
(1)
N
(2)
And Ccap⫽1⫹
OM [1⫺(1⫹r)−N] r
The second factor is the solar fraction that is defined as the ratio between
(3)
688
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
Solar fraction⫽
System output energy , Load
the useful output energy of the solar system, and the required load energy. The third effective factor in the comparison is the system efficiency that System efficiency⫽
System output energy , Input solar energy
the ratio between the output energy of the solar system to the input solar energy to the system.
3. Results and discussion Both optimum collector area and flow rate of the collector was deduced for each system to obtain the optimal system design. This optimization was decided based on the life-cycle savings of the system. The optimal design for each system was developed as follows: 3.1. Dyeing solar system The dyeing heat process in the factory needs hot water at only 80°C, but the steam is really used to heat the water to the required temperature. So, a solar system shown in Fig. 1 that can feed this process directly by hot water, with the boiler used only as an auxiliary of this system, was considered. According to the system performance improvement, the collector area is the most important factor that must be optimized. Moreover, the principal cost of the solar system is mainly dependent on the collector price. Therefore, the payback (life-cycle savings) of the system was calculated over the lifetime (i.e. 20 years was assumed as practical) as shown in Fig. 3 for different collector areas. The optimum collector area at which the system has the maximum life-cycle savings was obtained from Fig. 3 and equals 2300 m2. Fortunately, the roof area required for installing this collector area is available in the textile factory. Although this size area of collectors has a large initial cost (about 690,000 £E) it has maximum payback investment. At a collector area greater than the optimum one, the system output investment cannot pay back the extra in principal system cost. The solar fraction of this system was also calculated in Fig. 3 against different collector areas. As expected, the solar fraction is improved with a large collector area, i.e. the output energy of the solar system is increased. In Fig. 3 the system efficiency was also estimated to show the system performance according to the collector area. The maximum system efficiency is obtained at the collector area equal to 1600 m2, not at the optimal area (2300 m2) where the ratio between the cost of the useful energy to the principal cost of the system is maximized. Furthermore, the collector flow rate is the other factor that greatly affects the collector efficiency as well as the system efficiency. Furbo and Shah [3], Tolonen
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
Fig. 3.
689
Optimum collector area for the dyeing solar system.
and Lund [4], and Wuestling et al. [5] studied this point. They found that the optimum collector flow rate for the large solar systems is in between 0.0025 to 0.005 kg/m2 s. In fact, the load temperature affects the collector flow rate, so this point was considered in this study to determine the precise optimal collector flow rate. In Fig. 4, the life-cycle savings, solar fraction and the system efficiency were
Fig. 4.
Optimum collector flow rate for the dyeing processes.
690
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
calculated against the collector flow rate at the optimal collector area (i.e. 2300 m2). The optimal collector flow rate was estimated based on the payback of the system as before, and it was found to equal 0.004 kg/m2 s. This value is in the range that was indicated before by many authors [3–5]. The solar fraction and the system efficiency are also maximized at the similar point in which the system output energy is maximized. After estimating of the collector area and flow rate, the optimal system design was obtained because there are no other factors that can be optimized in this design. In the next section, the optimal design of the other system, the part-load system (preheat system) was studied to compare the two systems. Referring to Fig. 4, the system efficiency and the solar fraction are not affected greatly by collector flow rate. This is due to the small improvement in the useful energy output from the solar system with variable collector flow rate. However, the life-cycle savings are dependent only on the output energy in this case (the principal system cost is not changed), the optimum collector flow rate is located where the maximum system efficiency is obtained. 3.2. Preheat (part-load) system Similar steps were developed for this system (shown in Fig. 2) to optimize the system design. Thus, the optimal collector area was implemented in Fig. 5 and is equal to 1200 m2. The system efficiency is maximized also at this area wherever the solar fraction is dependent on the system output of energy. Unfortunately, the life-cycle savings have a negative sign for all collector areas and it means that the system investment cannot repay the principal cost of the system during its lifetime. The collector flow rate was also analyzed based on the life-cycle savings as
Fig. 5.
Optimum collector area for the pre-heat solar system.
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
691
presented in Fig. 6. From this figure it was found that the optimal flow rate that has the maximum life-cycle savings equals 0.002 kg/m2 s. It also has the maximum solar fraction and system efficiency tending to the maximum output energy of the system. This value is also near the range of the optimum collector flow rate that was decided before. From the above comparison between the two systems, the dyeing system is more practical than the part-load system as can be expected from the economic point of view. In addition, the dyeing system is also more efficient and its solar fraction is much more than the part-load system. Therefore, the dyeing system is highly recommended to be installed in the textile factory to feed the dyeing processes with hot water. The principal cost of the dyeing system is about 742,500 £E and the cost of the energy produced by this system is about 0.00031 £E/kWh. Whereas the annual energy produced is 2.719×106 kWh the average annual plant power is 755 kW. The environmental impact of this system was studied in the next section to obtain the potential of solar energy in this manner.
4. Environmental impact of the dyeing solar system To investigate the environmental impact of utilizing solar energy the different emissions from the solar-system manufacturing and the boiler combustion were estimated for the lifetime of the solar system. The air emission and the water emission as well as the wastes were calculated for the solar system and for the boiler operation to compare them from the environmental point of view. In this study only a limited selection of air and water pollutants, and some waste
Fig. 6.
Optimum collector flow rate for the pre-heat solar system.
692
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
categories which are responsible for the most important environmental problems (greenhouse effects, acid rain, summer smog, toxicological effects, pollution of surface water and long term risks of land filled waste), are elaborated and discussed. The environmental interventions are expressed in physical units of the emitted substances as, e.g. kg of CO2, CH4, SOx, NOx, etc. Mazzarella and Menard [6], and Frischknecht et al. [7] estimated different emissions for each solar system element. The quantity of this emission depends on the element size of the collector and the storage or depends on the required energy, such as the pumps and the boiler. Then, the different pollutants mass was calculated for both the solar system and the boiler, as shown in Figs 7–10. As can be seen in Fig. 7 there is a big difference in CO2 emission between the solar system and the boiler. The high reduction in CO2 pollution is the main advantage of using the solar fuel. This benefit is really approved when it is considered that CO2 is the most dangerous pollutant for the destruction of the environment, and the reduction of this emission from the industry costs much money. The oil boiler also has more other emissions of air and water than in the case of the solar system, and is presented in Fig. 8 and Fig. 9. The negative environmental impacts of solar energy systems include land displacement, and possible air and water pollution resulting from manufacturing, normal emergency operations, and demolition of the solar system. Land use does not become a problem where collectors are mounted on the roof. From the above results, it can be said that the environmental impact is an important factor in the decision to use solar energy that is yet more expensive than conventional fuel. The reality is the potential for solar energy to protect the environment from destructive emissions.
Fig. 7.
CO2 emissions for the solar system and for the boiler.
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
Fig. 8.
Fig. 9.
693
Other air-emissions for the solar system and for the boiler.
Water-borne emissions for the solar system and for the boiler.
5. Conclusion A feasibility study of using solar energy in the textile industry as a case study was carried out in this work. The optimal solar system that can feed the dyeing
694
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
Fig. 10.
Waste emissions for the solar system and for the boiler.
processes with hot water was obtained from the economic point of view. This system is more economic than the system that can be used as a preheat system for the boiler. The environmental study explained that the solar system is friendlier to the environment than the conventional fuels for different air and water emissions as well as waste emissions. The reduction of CO2 pollution is the main advantage of utilizing solar energy.
References [1] Duffe JA, Beckman WA. Solar Engineering of Thermal Processes. Canada: John Wiley & Sons, 1991. [2] Gordon, Rabl. Design, analysis and optimization of solar industrial process heat plants without storage. Solar Energy 1982; 28(6):519-530. [3] Furbo S, Shah LJ. Optimum solar collector fluid flow rate. In: Proceedings of Eurosun96, 16–19 September, 1996, Freiburg, Germany, 1996. [4] Tolonen JS, Lund PD. Experiments on large-scale solar heating with emphasis on the collector array design. In: Proceedings of Eurosun96, 16–19 September 1996, Freiburg, Germany, 1996. [5] Wuestling MD, Klein SA, Duffie JA. Promising control alternatives for solar water heating systems. Journal of Solar Energy Engineering 1985;107(215):215–21. [6] Mazzarella L, Menard M. Environmental assessment of a large-scale solar heating system. In: Proceedings of Eurosun96, 16–19 September 1996, Freiburg, Germany, 1996. [7] Frischknecht R, Hofstetter P, Knoepfel I, Dones R, Zollinger E. Energiesysteme. Zurich: ETH/PSI Villigen, 1994.
Potential of solar energy utilization in the textile industry — a case study Adel M. Abdel-Dayem a, M.A. Mohamad a
b,*
Mubarak City for Scientific Research, Informatics Research Institute, El-Dekheela, Alexandria, Egypt b NRC, Solar Energy Department, Tahrir Street, Dokki, Cairo, Egypt
Abstract There is high energy consumption in the industrial sector at low-temperature levels, and solar energy could save a considerable part of this energy. A feasibility study to obtain the potential of solar energy utilization in the textile industry is presented. Two categories were considered in this study. The first category is a preheat solar system that can feed the boiler with hot water. This system can be efficiently utilized in this case because it can operate under different conditions of flow rate and output temperature. The second category is to feed the process of textile dyeing that needs low temperatures (up to 85°C) directly with hot water. In this case, the collector area is limited by the available area in the factory. Economic comparison between the two categories was provided to determine the optimal system that can be used efficiently. The optimum design of the two systems was studied depending on the optimum collector area and flow rate. It was found that the second system is more economic and efficient than the first. The environmental impact of using such a system was studied for different air and water pollutants. Reduction of carbon dioxide emission was found to be the main advantage of using solar energy as a clean energy source. 2001 Elsevier Science Ltd. All rights reserved.
1. Introduction The textile industry is a case study in which solar energy can be practically utilized. Where lower temperatures are needed for the textile process-heat, solar energy can be efficiently used at this level. In this case a simple cheap control system is required to control the system operation. In addition, using the solar energy as an energy source can save a large amount of the energy consumed in this industry. A feasibility study was carried out for a textile factory (El-Shourbagy Textile
* Corresponding author. 0960-1481/01/$ - see front matter 2001 Elsevier Science Ltd. All rights reserved. PII: S 0 9 6 0 - 1 4 8 1 ( 0 0 ) 0 0 1 5 4 - 3
686
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
Nomenclature A cA cf CM c0 L M N OM qcol r rf hbackup
collector area, m2 collector price fuel price, (12 £E/GJ was considered) price of the storage tank, £E/kg fixed cost of collector system, £E life-cycle savings (payback), £E mass of the storage tank, kg lifetime of the collector, yr. (20 years was expected) annual charge for operation and maintenance of collector expressed as a fraction of capital cost (=2% was assumed) output energy of the collector, J real rate of return on alternative investments of comparable risk real fuel escalation rate boiler backup efficiency (75% was normally considered)
Factory, Cairo 30° N) to obtain the potential of solar energy in this field. The dyeing and drying of the textiles are the two processes that need a large amount of energy for heating in this industry. Where the hot water at 80°C is required for the dyeing process, the drying process needs steam to dry the wet textile. In this process, the textile is passed over a hot surface of a cylinder and the steam from a boiler heats the inside of the cylinder. Two solar systems were considered in this study. The first is a system that can feed the dyeing process directly with hot water and the other is a part-load system that can supply the boiler with hot water as a pre-heater. An economic comparison between the two systems was carried out based on the solar fraction (i.e. ratio of the solar system output to the load) and the system efficiency. The proposed two systems are shown in Fig. 1 and Fig. 2. The solar system in
Fig. 1.
Schematic diagram of the dyeing solar system.
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
687
Fig. 2. Schematic diagram of the pre-heat (part-load) solar system.
general consists of collector, storage tank, control, pipes and pump. In Fig. 2 the used steam in the drying process, which is about 50% of the total steam generated, is returned to the boiler while the total steam generated is about 20 ton/hr during 10 hours a day. On the other side the contaminated water that is used in the dyeing processes cannot be reused. The TRNSYS Program was used to design the two systems considered. The meteorological data such as the solar radiation and the ambient temperature, as well as the wind speed, were fitted from the monthly average values. The payback (lifecycle savings) and the solar fraction as well as the system efficiency were integrated along the year. Hence, the yearly average outputs were provided for each system.
2. Methodology The optimal system that was considered in this study has the maximum payback payment during the lifetime (20 years was assumed). That means this system is more efficient with relatively low principal cost. Some authors, as in [1] and [2], expected this method of optimization that is based on the life-cycle savings (payback investment) of the system. The life-cycle savings (L) are the difference between fuel savings and the cost of the capital, operation and maintenance ([2]), L⫽qcol·Cf,l⫺Ccap(c0⫹cA·A⫹cM·M) Cf,l⫽
冋 冋 册册
cf(1+rf) 1+rf 1⫺ hbackup(r−rf) 1+r
(1)
N
(2)
And Ccap⫽1⫹
OM [1⫺(1⫹r)−N] r
The second factor is the solar fraction that is defined as the ratio between
(3)
688
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
Solar fraction⫽
System output energy , Load
the useful output energy of the solar system, and the required load energy. The third effective factor in the comparison is the system efficiency that System efficiency⫽
System output energy , Input solar energy
the ratio between the output energy of the solar system to the input solar energy to the system.
3. Results and discussion Both optimum collector area and flow rate of the collector was deduced for each system to obtain the optimal system design. This optimization was decided based on the life-cycle savings of the system. The optimal design for each system was developed as follows: 3.1. Dyeing solar system The dyeing heat process in the factory needs hot water at only 80°C, but the steam is really used to heat the water to the required temperature. So, a solar system shown in Fig. 1 that can feed this process directly by hot water, with the boiler used only as an auxiliary of this system, was considered. According to the system performance improvement, the collector area is the most important factor that must be optimized. Moreover, the principal cost of the solar system is mainly dependent on the collector price. Therefore, the payback (life-cycle savings) of the system was calculated over the lifetime (i.e. 20 years was assumed as practical) as shown in Fig. 3 for different collector areas. The optimum collector area at which the system has the maximum life-cycle savings was obtained from Fig. 3 and equals 2300 m2. Fortunately, the roof area required for installing this collector area is available in the textile factory. Although this size area of collectors has a large initial cost (about 690,000 £E) it has maximum payback investment. At a collector area greater than the optimum one, the system output investment cannot pay back the extra in principal system cost. The solar fraction of this system was also calculated in Fig. 3 against different collector areas. As expected, the solar fraction is improved with a large collector area, i.e. the output energy of the solar system is increased. In Fig. 3 the system efficiency was also estimated to show the system performance according to the collector area. The maximum system efficiency is obtained at the collector area equal to 1600 m2, not at the optimal area (2300 m2) where the ratio between the cost of the useful energy to the principal cost of the system is maximized. Furthermore, the collector flow rate is the other factor that greatly affects the collector efficiency as well as the system efficiency. Furbo and Shah [3], Tolonen
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
Fig. 3.
689
Optimum collector area for the dyeing solar system.
and Lund [4], and Wuestling et al. [5] studied this point. They found that the optimum collector flow rate for the large solar systems is in between 0.0025 to 0.005 kg/m2 s. In fact, the load temperature affects the collector flow rate, so this point was considered in this study to determine the precise optimal collector flow rate. In Fig. 4, the life-cycle savings, solar fraction and the system efficiency were
Fig. 4.
Optimum collector flow rate for the dyeing processes.
690
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
calculated against the collector flow rate at the optimal collector area (i.e. 2300 m2). The optimal collector flow rate was estimated based on the payback of the system as before, and it was found to equal 0.004 kg/m2 s. This value is in the range that was indicated before by many authors [3–5]. The solar fraction and the system efficiency are also maximized at the similar point in which the system output energy is maximized. After estimating of the collector area and flow rate, the optimal system design was obtained because there are no other factors that can be optimized in this design. In the next section, the optimal design of the other system, the part-load system (preheat system) was studied to compare the two systems. Referring to Fig. 4, the system efficiency and the solar fraction are not affected greatly by collector flow rate. This is due to the small improvement in the useful energy output from the solar system with variable collector flow rate. However, the life-cycle savings are dependent only on the output energy in this case (the principal system cost is not changed), the optimum collector flow rate is located where the maximum system efficiency is obtained. 3.2. Preheat (part-load) system Similar steps were developed for this system (shown in Fig. 2) to optimize the system design. Thus, the optimal collector area was implemented in Fig. 5 and is equal to 1200 m2. The system efficiency is maximized also at this area wherever the solar fraction is dependent on the system output of energy. Unfortunately, the life-cycle savings have a negative sign for all collector areas and it means that the system investment cannot repay the principal cost of the system during its lifetime. The collector flow rate was also analyzed based on the life-cycle savings as
Fig. 5.
Optimum collector area for the pre-heat solar system.
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
691
presented in Fig. 6. From this figure it was found that the optimal flow rate that has the maximum life-cycle savings equals 0.002 kg/m2 s. It also has the maximum solar fraction and system efficiency tending to the maximum output energy of the system. This value is also near the range of the optimum collector flow rate that was decided before. From the above comparison between the two systems, the dyeing system is more practical than the part-load system as can be expected from the economic point of view. In addition, the dyeing system is also more efficient and its solar fraction is much more than the part-load system. Therefore, the dyeing system is highly recommended to be installed in the textile factory to feed the dyeing processes with hot water. The principal cost of the dyeing system is about 742,500 £E and the cost of the energy produced by this system is about 0.00031 £E/kWh. Whereas the annual energy produced is 2.719×106 kWh the average annual plant power is 755 kW. The environmental impact of this system was studied in the next section to obtain the potential of solar energy in this manner.
4. Environmental impact of the dyeing solar system To investigate the environmental impact of utilizing solar energy the different emissions from the solar-system manufacturing and the boiler combustion were estimated for the lifetime of the solar system. The air emission and the water emission as well as the wastes were calculated for the solar system and for the boiler operation to compare them from the environmental point of view. In this study only a limited selection of air and water pollutants, and some waste
Fig. 6.
Optimum collector flow rate for the pre-heat solar system.
692
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
categories which are responsible for the most important environmental problems (greenhouse effects, acid rain, summer smog, toxicological effects, pollution of surface water and long term risks of land filled waste), are elaborated and discussed. The environmental interventions are expressed in physical units of the emitted substances as, e.g. kg of CO2, CH4, SOx, NOx, etc. Mazzarella and Menard [6], and Frischknecht et al. [7] estimated different emissions for each solar system element. The quantity of this emission depends on the element size of the collector and the storage or depends on the required energy, such as the pumps and the boiler. Then, the different pollutants mass was calculated for both the solar system and the boiler, as shown in Figs 7–10. As can be seen in Fig. 7 there is a big difference in CO2 emission between the solar system and the boiler. The high reduction in CO2 pollution is the main advantage of using the solar fuel. This benefit is really approved when it is considered that CO2 is the most dangerous pollutant for the destruction of the environment, and the reduction of this emission from the industry costs much money. The oil boiler also has more other emissions of air and water than in the case of the solar system, and is presented in Fig. 8 and Fig. 9. The negative environmental impacts of solar energy systems include land displacement, and possible air and water pollution resulting from manufacturing, normal emergency operations, and demolition of the solar system. Land use does not become a problem where collectors are mounted on the roof. From the above results, it can be said that the environmental impact is an important factor in the decision to use solar energy that is yet more expensive than conventional fuel. The reality is the potential for solar energy to protect the environment from destructive emissions.
Fig. 7.
CO2 emissions for the solar system and for the boiler.
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
Fig. 8.
Fig. 9.
693
Other air-emissions for the solar system and for the boiler.
Water-borne emissions for the solar system and for the boiler.
5. Conclusion A feasibility study of using solar energy in the textile industry as a case study was carried out in this work. The optimal solar system that can feed the dyeing
694
A.M. Abdel-Dayem, M.A. Mohamad / Renewable Energy 23 (2001) 685–694
Fig. 10.
Waste emissions for the solar system and for the boiler.
processes with hot water was obtained from the economic point of view. This system is more economic than the system that can be used as a preheat system for the boiler. The environmental study explained that the solar system is friendlier to the environment than the conventional fuels for different air and water emissions as well as waste emissions. The reduction of CO2 pollution is the main advantage of utilizing solar energy.
References [1] Duffe JA, Beckman WA. Solar Engineering of Thermal Processes. Canada: John Wiley & Sons, 1991. [2] Gordon, Rabl. Design, analysis and optimization of solar industrial process heat plants without storage. Solar Energy 1982; 28(6):519-530. [3] Furbo S, Shah LJ. Optimum solar collector fluid flow rate. In: Proceedings of Eurosun96, 16–19 September, 1996, Freiburg, Germany, 1996. [4] Tolonen JS, Lund PD. Experiments on large-scale solar heating with emphasis on the collector array design. In: Proceedings of Eurosun96, 16–19 September 1996, Freiburg, Germany, 1996. [5] Wuestling MD, Klein SA, Duffie JA. Promising control alternatives for solar water heating systems. Journal of Solar Energy Engineering 1985;107(215):215–21. [6] Mazzarella L, Menard M. Environmental assessment of a large-scale solar heating system. In: Proceedings of Eurosun96, 16–19 September 1996, Freiburg, Germany, 1996. [7] Frischknecht R, Hofstetter P, Knoepfel I, Dones R, Zollinger E. Energiesysteme. Zurich: ETH/PSI Villigen, 1994.