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Grid connected solar photovoltaic system as a tool for green house gas emission reduction in Turkey
Renewable and Sustainable Energy Reviews 53 (2016) 1086–1091
Contents lists available at ScienceDirect
Renewable and Sustainable Energy Reviews journal homepage: www.elsevier.com/locate/rser
Grid connected solar photovoltaic system as a tool for green house gas emission reduction in Turkey Aminu Dankaka Adam, Gokhan Apaydin n Department of Electrical-Electronics Engineering, Zirve University, Gaziantep 27260, Turkey
art ic l e i nf o
a b s t r a c t
Article history: Received 24 December 2014 Received in revised form 26 May 2015 Accepted 18 September 2015 Available online 10 November 2015
Energy production in a safe and hazard free manner is one of the world's greatest concern. Since the inception of Kyoto Protocol, which was adopted in 1997 and entered into force in February 2005, countries have started to adopt different measures for emission reduction such as electricity generation from renewable energy sources; as the source is free from green house gas (GHG) or CO2 emission. Legislations and financial incentives have been provided by some governments for encouragement and ensuring good returns to the investors in renewable energy sector. This paper analyzes how a 500 kWp solar photovoltaic (PV) system for electricity generation contributes significantly in the GHG emission reduction and also the potential impact of introducing CO2 emission reduction cost in the solar PV electricity generation. The result shows that the emission reduction is of the order of hundreds of tons of CO2 and CO2 emission reduction cost has a positive impact on the cumulative cash flow of the system. & 2015 Elsevier Ltd. All rights reserved.
Keywords: Renewable energy Green house gas emission Solar photovoltaic system CO2 emission reduction cost
Contents 1. 2. 3.
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solar photovoltaic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Factors affecting potential availability and price of PV generated electricity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1. Intermittence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2. Transmission constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3. Material availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4. PV cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. GHG terminologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. Green house gases (GHG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2. Carbon dioxide (CO2) equivalent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3. Carbon footprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4. Carbon offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. Fuel mix, GHG avoidance, and GHG emission factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. Case study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. Results and discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1. Introduction n
Corresponding author. Tel.: þ 90 342 211 6793; fax: þ90 342 211 6677. E-mail addresses: [email protected] (A.D. Adam), [email protected] (G. Apaydin). http://dx.doi.org/10.1016/j.rser.2015.09.023 1364-0321/& 2015 Elsevier Ltd. All rights reserved.
Energy production in a safe and hazard-free manner is one of the world's greatest concerns. Many analyses have shown that substituting conventional energy sources (such as natural gas, coal, etc.) with
A.D. Adam, G. Apaydin / Renewable and Sustainable Energy Reviews 53 (2016) 1086–1091
non-conventional sources (such as solar, wind, etc.) for electricity generation would result in drastic green house gas (GHG) emission reduction [1–7]. Since the inception of Kyoto Protocol, which was adopted in 1997 and entered into force in February 2005 [8], countries have started to adopt different measures for emission reduction ranging from generating electricity from non-conventional or renewable energy sources; pricing policy in significant GHG emission reduction and preferential price known as feed-in-tariff for encouragement and ensuring good returns to the investors in renewable energy sector [1]. This paper analyzes how 500 kWp (kiloWatt peak) electrical power generated from solar photovoltaic (PV) system design based on the solar data of Gaziantep city in Turkey contributes significantly in the GHG emission reduction and also the potential impact of introducing CO2 emission reduction cost in the solar PV electricity generation has been analyzed for the proposed power case.
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day [14]. Translating these insulation values to usable electricity depends on the PV conversion efficiency, the inverter loses, wiring, and other system component losses [10]. Fig. 1 provides an overview of annual variation of solar electricity generated by 1 kWp PV system in different cities of Turkey [14]. Turkey has seven regions that are divided according to climate, location, flora and fauna, human habitat agricultural diversity, transportation, topography, etc. Each region has different solar potentials as shown in Table 1 [14]. It is seen from Table 1 that the southeastern Anatolia region has the best condition of solar energy and Gaziantep is one of the biggest city in the region. For these reason, Gaziantep is chosen as a case study; as the city is experiencing intensive investments such as modern buildings and new industries. Gaziantep has good solar energy potentials with an average irradiation of 1460 kW h/m2 per year and approximately sunshine duration hours of 2993 annually [14]. Therefore, solar energy has a big role to play in satisfying energy demand of the city as well as reducing its GHG emission [15].
2. Solar photovoltaic Solar PV modules (or group of PV cells) are made of semiconductor material and are normally arranged as arrays of individual modules use to convert sunlight into direct electric current, which later is converted into alternating current through an inverter if the system output is to be connected to the grid [9]. In 1950s, the first cell was built with less than 4% efficiency [10] since then the efficiency of the cell is substantially improved over time with a drastic decrease in its price. The current PV cell available for commercial has an average efficiency ranging from 15% to 20% [11]. Turkey has a good geographical location to develop solar power plants as it lies in a sunny belt between 36° and 42° North latitudes and between 26° and 45° East longitudes, bordering the Mediterranean, Aegean, and Black Seas [12]. The Mediterranean Sun Belt goes through the country, placing Turkey in one of the most strategic positions in Europe for the purposes of generating solar power [13]. Every year, the expected average solar irradiation in Turkey is 1311 kW h/m2 per-year and 3.6 kW h/m2 per-day and the total annual insulation period (amount of solar energy striking a flat surface overtime) of approximately 2460 h per-year and 7.2 h per-
3. Factors affecting potential availability and price of PV generated electricity 3.1. Intermittence Intermittence is the variability of the solar resources which results from the variation in the generation that depends on the Table 1 Regional distribution of Turkey's annual solar energy potential [20]. Regions
Total solar energy (kW h/m2-year)
Sunshine duration (h/year)
Southeast Anatolia Mediterranean Eastern Anatolia Central Anatolia Aegean Marmara Black Sea
1460 1390 1365 1314 1304 1168 1120
2993 2956 2664 2628 2738 2409 1971
Fig. 1. Annual variation of solar electricity generated by 1 kWp PV system [20].
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availability of the renewable sources (e.g. sunlight). Intermittence limits the resource contribution to the grid as well [16]. To reduce any negative effect that may result from the intermittence of the renewable energy sources and to attain maximum utilization and manage high level of reliability of this source, adaptable advance control system is paramount, or enabling technology such as storage [17]. Electricity generation by PV system itself could provide large share of system's electricity if there exist a storage system at reasonable cost. 3.2. Transmission constraints Potential reduction of the intermittence can be achieved by increasing the special diversity and also the cost of the PV generated electricity could be lowered for the location with poor solar resources when there is a good transmission system with less constraint [18]. 3.3. Material availability Material constrain in the other type of certain advanced PV technologies (such as thin-film) that could have effects on the PV generated electricity. This is despite the fact that for many other types of PV technologies, the materials are unlimited for any estimated demand [19]. 3.4. PV cost The PV cost is also another factor affecting potential availability and price of PV generated electricity. Different governmental strategies are in place with the aim of reducing the cost of the PV systems. These strategies involve sustainable and adequate research and development effort with the aim of reducing the PV module cost, improving the module efficiency and system design as well [20]. Despite the factors mentioned above, from 1995 to 2013 global PV market experienced a promising advancement with an average 40% annual growth rate as shown in Fig. 2 [21].
burning, trees and wood products, solid waste and certain chemical reactions, nitrous oxide (N2O) that results from industrial and agricultural activities, solid waste and fossil fuel combustion and methane (CH4) which results from transport and production of natural gas, oil and coal and also from other agricultural practices and livestock among others. Since the industrial revolution greenhouse gas emission increases worldwide, and each country produces these gases, some far more than the others depending on the economic activity, income level, population, climate condition and land use. This led to the high increase in the concentration of the green house gases in the atmosphere [22]. 4.2. Carbon dioxide (CO2) equivalent Irrespective of the gases composed in the GHG, it is collectively referred as CO2 emission. This is because CO2 gas gives a reference that permits comparability with the other GH gases global warming potential (GWP). The emission can be found in a number of methods. These include emission factor, direct and monitoring measurement, engineering estimates, and mass balance [22]. 4.3. Carbon footprint Carbon footprint is attributed to the GHG source as it measures the quality of the GHG based on the environmental impact of a particular operation or individual or organization lifestyle [23]. It can be primary footprint, i.e. from the summation of direct emission from the combustion of fossil fuels or secondary footprint i.e. from the summation of indirect emission from the good and services. 4.4. Carbon offset Carbon offset is a credit set by an organization or individual to reduce the GHG emission in order to offset the GHG emission made elsewhere [22]. The organization or individual is carbon free, if their number of carbon offset is same as their carbon footprint.
5. Fuel mix, GHG avoidance, and GHG emission factor 4. GHG terminologies 4.1. Green house gases (GHG) Green house gases are gases in the atmosphere that trap heat, which are major contributor to the climate change. These gases are composed of carbon dioxide (CO2) that comes from fossil fuel
Fuel mix is a combination of more than one energy source for electrical power generation in a country. This is necessary to avoid total dependency on a single or one particular source, and to explore the available natural resources around as well as to ensure environmental and ecological protection from GHG emission. GHG avoidance is a measure taken in reducing the intensity of the GHG emission during electrical power generation that uses conventional energy sources. Therefore, for a country to lower GHG emission rate, it should have high renewable energy portion in its fuel mix. GHG emission factor is an indicator of how much GHG (CO2, N2O, CH4, etc.) is emitted for every kW h of electricity generated. This factor can vary from one energy supply company to the other depending on the technology and the energy source used. It is normally measured in kilogram per kiloWatt hour (kg/ kW h) or ton per kiloWatt hour (t/kW h) of the saved CO2 as the remaining gases are all converted to CO2 equivalent in terms of their GWP [22].
6. Case study
Fig. 2. Solar PV global capacity 1995–2013 [21].
As it is mentioned, Gaziantep city has been chosen as a case study as it has good solar energy potentials with an average irradiation of 1460 kW h/m2 per year and approximately sunshine duration hours of 2993 annually. A 500 kWp solar photovoltaic
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system, designed and presently under construction in Nizip, Gaziantep city has been considered for study. All necessary solar radiation data required for the design are obtained from RETScreen “The RETScreen is a Clean Energy Project Analysis software, designed by Department of Natural Resources Canada which has a broad database of meteorological data including global daily horizontal solar irradiance and also a database of various renewable energy systems components from different manufacturers” [24]. The implications of RETScreen international as commercial software have been assessed by the firm SGA Energy Limited (founded in 1988, a trusted Canadian sustainable energy and climate change consulting firm). For both present, i.e. 1998–2004, and the future, i.e. up to 2012, and for Canada and the world. There is no much issue with the validity of the results obtained from the software. Future implications have been considered under two RETScreen funding issues; i.e. discontinued and continued funding at the present level. For these two periods the implication of the RETScreen software has been evaluated against four performances, i.e. cumulative user savings in relation to RETScreen International as a result of people using the software and related tools; cumulative installed capacity of clean energy projects built in relation with RETScreen use; cumulative installed value of these projects and the annual greenhouse gas emission reductions of the clean energy projects built that can be associated with RETScreen use. SGA concludes after comparing the continued funding and discontinued funding scenarios that further investment through 2012 will help save billions of dollars for the RETScreen users worldwide. They also conclude that the value of these added to energy efficiency measures associated with RETScreen use will be in the order of billions of dollars. Annual CO2 savings for the world, impacts will be substantially higher [25]. The formulation procedure of the design principle for the daily and annual energy generated by the system as well as the system capacity factor is as follows. The solar radiation data from RETScreen shows that the Gaziantep city has an average irradiation value of 4.83 kW h/m2 per day. The power generated per day is 500 kWp 4.83¼2415 kW h. The result can also be written as 2.415 MW h per day. The capacity factor in percent is 20.125% obtained as the ratio of actual energy produced by the system annually (2.145 MW h 365¼ 881.475 MW h per year) to annual system energy at a constant rated power (24 365 500 kW¼4380 MW h per year). This capacity factor measures the productivity of the energy generating resource. The typical range
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capacity factor of PV system is from 5% to 20% [24]. Capacity factor of 19% has been proposed for grid connected system as a function of high temperature performance of the PV panel, panel orientation to the sun, insulation of the project location or efficiency of the electrical system [11]. Therefore, a capacity factor of 20.125% for the insulation value of the Gaziantep is a good value to be considered for a grid connected solar PV system in that particular location. For this particular study, the following information has been given to the software as a proposed power case for the energy model as shown in Table 2.
7. Results and discussion Through using the RETScreen software, the CO2 emission reduction from the proposed energy model has been examined. The RETScreen is used to determine the annual GHG emission reduction for the project compared to conventional technology based cases and the results are presented in terms of tons of CO2 per-year that will be equivalent to the emission reduction regardless of the actual gases composed in the emission, and this is achieved by converting CH4 and N2O to the equivalent CO2 Table 2 Proposed case power system. System type Power capacity Longitude and latitude Heating and cooling design value Earth temperature Capacity factor Electricity exported to the grid
Photovoltaic 500 kWp 37.82105° long., 37.120010° lat. 10° and 70° 25° 20.1% 881.5 MW h
Table 3 GHG emission reduction of 500 kWp SPV system, base case electricity system. Country region (Turkey-Gaziantep). Fuel type
GHG emission factor (tCO2/ MW h)
Coal 1.059 Oil 0.779 Natural gas 0.376
Annual GHG emission reduction (tCO2)
Equivalent of barrel of crude oil not consumed
933.2 686.9 331.4
2170 159 771
Fig. 3. Financial analysis with the effect of GHG emission reduction income from coal on annual savings and incomes.
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Fig. 4. Financial analysis with the effect of GHG emission reduction income from oil on annual savings and incomes.
Fig. 5. Financial analysis with the effect of GHG emission reduction income from natural gas on annual savings and incomes.
Table 4 Financial input parameters [27]. GHG reduction credit rate Inflation rate Project life Debt ratio Debt term Debt term Total initial cost
Table 5 Financial analysis result without emission reduction price [25]. USD/tCO2 736.5 9.0% 25 years 70% 4.50% 7 years USD 702,000
emission in terms of their GWP and it also adjusts the reduction to account for transmission and distribution losses and GHG credit if any [24]. The GHG emission factors of three different types of fuel are available in the software. Table 3 shows the emission factors based on the available fuel type in RETScreen software. Analysis of the result shows that the project annually supply 881.475 MW h/year of electricity. And also this 500 kWp PV system serves as a means of reducing 933.2, 686.9, or 331.4 tons of greenhouse gas emission to the atmosphere when compared with
Total annual cost and debt payment Total annual savings and income Pre-tax IRR – equity Pre-tax IRR – asset Simple payback Equity payback
USD 83,391.00 USD 124,288.00 44.2% 21.9% 5.6 years 3.2 years
the same amount of electricity generated using coal, oil or natural gas respectively as the energy source. With the current feed-intariff of the country, it is interesting to note that the project has a simple payback period of 5.6 years only as shown in Table 5. This is almost less than one quarter of the project life of 25 years [24]. Also the project has a good internal rate of return. Thus, the project can be considered desirable to be implemented since it is proven to be environmentally beneficial and financially viable and profitable.
A.D. Adam, G. Apaydin / Renewable and Sustainable Energy Reviews 53 (2016) 1086–1091
Considering the emission factor presented in Table 3, the annual GHG emission reduction and the number of barrel of crude oil saved, it is evident that the reduction in the emission could reach a higher rate if the energy generation from PV could be of higher percentage in the electricity generation sector. This can only be possible if government can provide incentives for the development of renewable PV plants, which could serve as a means of encouraging private investors. Incentives could also result in a huge investment in the sector and consequently, large emission reduction of the GHG. The income generated from the GHG reduction of the solar PV system is very high as it accounted for averagely 537 Euro equivalent to 736.5 USD per ton of CO2 in Germany from 2006 to 2010 [26]. A clear effect of GHG emission reduction income could be seen in the financial analysis of the solar PV system as shown in Figs. 3–5. To financially analyze the system, the following data have been given to the RETScreen as financial input parameters as shown in Table 4 [27].
8. Conclusion This paper estimates the annual GHG or CO2 emission reduction capacity of grid-connected solar PV system in Gaziantep city of Turkey which has been compared with “equivalent of barrel of crude oil not consumed” using RETScreen software. It is concluded that the emission reduction capacity of the PV system is reasonable and it should be highly recommended as one of the major tool in CO2 emission reduction. But increasing the share of the solar PV system can only be achieved if there is adequate financial incentive provided by the government [26]. Government should lay down certain legislations that will ease the procedures followed for construction of generation facilities. This is because the complex procedures in obtaining the permits for the construction of generation facilities with lower installed capacity is one of the major factor affecting the solar PV system construction. These measures will serve as a means of encouragement to the private investor; which will result in the large share of PV electricity generation plant as a consequent high CO2 emission reduction.
Acknowledgements The authors gratefully acknowledge Safar Al-Hilal for his constructive comments.
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Contents lists available at ScienceDirect
Renewable and Sustainable Energy Reviews journal homepage: www.elsevier.com/locate/rser
Grid connected solar photovoltaic system as a tool for green house gas emission reduction in Turkey Aminu Dankaka Adam, Gokhan Apaydin n Department of Electrical-Electronics Engineering, Zirve University, Gaziantep 27260, Turkey
art ic l e i nf o
a b s t r a c t
Article history: Received 24 December 2014 Received in revised form 26 May 2015 Accepted 18 September 2015 Available online 10 November 2015
Energy production in a safe and hazard free manner is one of the world's greatest concern. Since the inception of Kyoto Protocol, which was adopted in 1997 and entered into force in February 2005, countries have started to adopt different measures for emission reduction such as electricity generation from renewable energy sources; as the source is free from green house gas (GHG) or CO2 emission. Legislations and financial incentives have been provided by some governments for encouragement and ensuring good returns to the investors in renewable energy sector. This paper analyzes how a 500 kWp solar photovoltaic (PV) system for electricity generation contributes significantly in the GHG emission reduction and also the potential impact of introducing CO2 emission reduction cost in the solar PV electricity generation. The result shows that the emission reduction is of the order of hundreds of tons of CO2 and CO2 emission reduction cost has a positive impact on the cumulative cash flow of the system. & 2015 Elsevier Ltd. All rights reserved.
Keywords: Renewable energy Green house gas emission Solar photovoltaic system CO2 emission reduction cost
Contents 1. 2. 3.
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solar photovoltaic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Factors affecting potential availability and price of PV generated electricity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1. Intermittence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2. Transmission constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3. Material availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4. PV cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. GHG terminologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. Green house gases (GHG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2. Carbon dioxide (CO2) equivalent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3. Carbon footprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4. Carbon offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. Fuel mix, GHG avoidance, and GHG emission factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. Case study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. Results and discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1. Introduction n
Corresponding author. Tel.: þ 90 342 211 6793; fax: þ90 342 211 6677. E-mail addresses: [email protected] (A.D. Adam), [email protected] (G. Apaydin). http://dx.doi.org/10.1016/j.rser.2015.09.023 1364-0321/& 2015 Elsevier Ltd. All rights reserved.
Energy production in a safe and hazard-free manner is one of the world's greatest concerns. Many analyses have shown that substituting conventional energy sources (such as natural gas, coal, etc.) with
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non-conventional sources (such as solar, wind, etc.) for electricity generation would result in drastic green house gas (GHG) emission reduction [1–7]. Since the inception of Kyoto Protocol, which was adopted in 1997 and entered into force in February 2005 [8], countries have started to adopt different measures for emission reduction ranging from generating electricity from non-conventional or renewable energy sources; pricing policy in significant GHG emission reduction and preferential price known as feed-in-tariff for encouragement and ensuring good returns to the investors in renewable energy sector [1]. This paper analyzes how 500 kWp (kiloWatt peak) electrical power generated from solar photovoltaic (PV) system design based on the solar data of Gaziantep city in Turkey contributes significantly in the GHG emission reduction and also the potential impact of introducing CO2 emission reduction cost in the solar PV electricity generation has been analyzed for the proposed power case.
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day [14]. Translating these insulation values to usable electricity depends on the PV conversion efficiency, the inverter loses, wiring, and other system component losses [10]. Fig. 1 provides an overview of annual variation of solar electricity generated by 1 kWp PV system in different cities of Turkey [14]. Turkey has seven regions that are divided according to climate, location, flora and fauna, human habitat agricultural diversity, transportation, topography, etc. Each region has different solar potentials as shown in Table 1 [14]. It is seen from Table 1 that the southeastern Anatolia region has the best condition of solar energy and Gaziantep is one of the biggest city in the region. For these reason, Gaziantep is chosen as a case study; as the city is experiencing intensive investments such as modern buildings and new industries. Gaziantep has good solar energy potentials with an average irradiation of 1460 kW h/m2 per year and approximately sunshine duration hours of 2993 annually [14]. Therefore, solar energy has a big role to play in satisfying energy demand of the city as well as reducing its GHG emission [15].
2. Solar photovoltaic Solar PV modules (or group of PV cells) are made of semiconductor material and are normally arranged as arrays of individual modules use to convert sunlight into direct electric current, which later is converted into alternating current through an inverter if the system output is to be connected to the grid [9]. In 1950s, the first cell was built with less than 4% efficiency [10] since then the efficiency of the cell is substantially improved over time with a drastic decrease in its price. The current PV cell available for commercial has an average efficiency ranging from 15% to 20% [11]. Turkey has a good geographical location to develop solar power plants as it lies in a sunny belt between 36° and 42° North latitudes and between 26° and 45° East longitudes, bordering the Mediterranean, Aegean, and Black Seas [12]. The Mediterranean Sun Belt goes through the country, placing Turkey in one of the most strategic positions in Europe for the purposes of generating solar power [13]. Every year, the expected average solar irradiation in Turkey is 1311 kW h/m2 per-year and 3.6 kW h/m2 per-day and the total annual insulation period (amount of solar energy striking a flat surface overtime) of approximately 2460 h per-year and 7.2 h per-
3. Factors affecting potential availability and price of PV generated electricity 3.1. Intermittence Intermittence is the variability of the solar resources which results from the variation in the generation that depends on the Table 1 Regional distribution of Turkey's annual solar energy potential [20]. Regions
Total solar energy (kW h/m2-year)
Sunshine duration (h/year)
Southeast Anatolia Mediterranean Eastern Anatolia Central Anatolia Aegean Marmara Black Sea
1460 1390 1365 1314 1304 1168 1120
2993 2956 2664 2628 2738 2409 1971
Fig. 1. Annual variation of solar electricity generated by 1 kWp PV system [20].
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availability of the renewable sources (e.g. sunlight). Intermittence limits the resource contribution to the grid as well [16]. To reduce any negative effect that may result from the intermittence of the renewable energy sources and to attain maximum utilization and manage high level of reliability of this source, adaptable advance control system is paramount, or enabling technology such as storage [17]. Electricity generation by PV system itself could provide large share of system's electricity if there exist a storage system at reasonable cost. 3.2. Transmission constraints Potential reduction of the intermittence can be achieved by increasing the special diversity and also the cost of the PV generated electricity could be lowered for the location with poor solar resources when there is a good transmission system with less constraint [18]. 3.3. Material availability Material constrain in the other type of certain advanced PV technologies (such as thin-film) that could have effects on the PV generated electricity. This is despite the fact that for many other types of PV technologies, the materials are unlimited for any estimated demand [19]. 3.4. PV cost The PV cost is also another factor affecting potential availability and price of PV generated electricity. Different governmental strategies are in place with the aim of reducing the cost of the PV systems. These strategies involve sustainable and adequate research and development effort with the aim of reducing the PV module cost, improving the module efficiency and system design as well [20]. Despite the factors mentioned above, from 1995 to 2013 global PV market experienced a promising advancement with an average 40% annual growth rate as shown in Fig. 2 [21].
burning, trees and wood products, solid waste and certain chemical reactions, nitrous oxide (N2O) that results from industrial and agricultural activities, solid waste and fossil fuel combustion and methane (CH4) which results from transport and production of natural gas, oil and coal and also from other agricultural practices and livestock among others. Since the industrial revolution greenhouse gas emission increases worldwide, and each country produces these gases, some far more than the others depending on the economic activity, income level, population, climate condition and land use. This led to the high increase in the concentration of the green house gases in the atmosphere [22]. 4.2. Carbon dioxide (CO2) equivalent Irrespective of the gases composed in the GHG, it is collectively referred as CO2 emission. This is because CO2 gas gives a reference that permits comparability with the other GH gases global warming potential (GWP). The emission can be found in a number of methods. These include emission factor, direct and monitoring measurement, engineering estimates, and mass balance [22]. 4.3. Carbon footprint Carbon footprint is attributed to the GHG source as it measures the quality of the GHG based on the environmental impact of a particular operation or individual or organization lifestyle [23]. It can be primary footprint, i.e. from the summation of direct emission from the combustion of fossil fuels or secondary footprint i.e. from the summation of indirect emission from the good and services. 4.4. Carbon offset Carbon offset is a credit set by an organization or individual to reduce the GHG emission in order to offset the GHG emission made elsewhere [22]. The organization or individual is carbon free, if their number of carbon offset is same as their carbon footprint.
5. Fuel mix, GHG avoidance, and GHG emission factor 4. GHG terminologies 4.1. Green house gases (GHG) Green house gases are gases in the atmosphere that trap heat, which are major contributor to the climate change. These gases are composed of carbon dioxide (CO2) that comes from fossil fuel
Fuel mix is a combination of more than one energy source for electrical power generation in a country. This is necessary to avoid total dependency on a single or one particular source, and to explore the available natural resources around as well as to ensure environmental and ecological protection from GHG emission. GHG avoidance is a measure taken in reducing the intensity of the GHG emission during electrical power generation that uses conventional energy sources. Therefore, for a country to lower GHG emission rate, it should have high renewable energy portion in its fuel mix. GHG emission factor is an indicator of how much GHG (CO2, N2O, CH4, etc.) is emitted for every kW h of electricity generated. This factor can vary from one energy supply company to the other depending on the technology and the energy source used. It is normally measured in kilogram per kiloWatt hour (kg/ kW h) or ton per kiloWatt hour (t/kW h) of the saved CO2 as the remaining gases are all converted to CO2 equivalent in terms of their GWP [22].
6. Case study
Fig. 2. Solar PV global capacity 1995–2013 [21].
As it is mentioned, Gaziantep city has been chosen as a case study as it has good solar energy potentials with an average irradiation of 1460 kW h/m2 per year and approximately sunshine duration hours of 2993 annually. A 500 kWp solar photovoltaic
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system, designed and presently under construction in Nizip, Gaziantep city has been considered for study. All necessary solar radiation data required for the design are obtained from RETScreen “The RETScreen is a Clean Energy Project Analysis software, designed by Department of Natural Resources Canada which has a broad database of meteorological data including global daily horizontal solar irradiance and also a database of various renewable energy systems components from different manufacturers” [24]. The implications of RETScreen international as commercial software have been assessed by the firm SGA Energy Limited (founded in 1988, a trusted Canadian sustainable energy and climate change consulting firm). For both present, i.e. 1998–2004, and the future, i.e. up to 2012, and for Canada and the world. There is no much issue with the validity of the results obtained from the software. Future implications have been considered under two RETScreen funding issues; i.e. discontinued and continued funding at the present level. For these two periods the implication of the RETScreen software has been evaluated against four performances, i.e. cumulative user savings in relation to RETScreen International as a result of people using the software and related tools; cumulative installed capacity of clean energy projects built in relation with RETScreen use; cumulative installed value of these projects and the annual greenhouse gas emission reductions of the clean energy projects built that can be associated with RETScreen use. SGA concludes after comparing the continued funding and discontinued funding scenarios that further investment through 2012 will help save billions of dollars for the RETScreen users worldwide. They also conclude that the value of these added to energy efficiency measures associated with RETScreen use will be in the order of billions of dollars. Annual CO2 savings for the world, impacts will be substantially higher [25]. The formulation procedure of the design principle for the daily and annual energy generated by the system as well as the system capacity factor is as follows. The solar radiation data from RETScreen shows that the Gaziantep city has an average irradiation value of 4.83 kW h/m2 per day. The power generated per day is 500 kWp 4.83¼2415 kW h. The result can also be written as 2.415 MW h per day. The capacity factor in percent is 20.125% obtained as the ratio of actual energy produced by the system annually (2.145 MW h 365¼ 881.475 MW h per year) to annual system energy at a constant rated power (24 365 500 kW¼4380 MW h per year). This capacity factor measures the productivity of the energy generating resource. The typical range
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capacity factor of PV system is from 5% to 20% [24]. Capacity factor of 19% has been proposed for grid connected system as a function of high temperature performance of the PV panel, panel orientation to the sun, insulation of the project location or efficiency of the electrical system [11]. Therefore, a capacity factor of 20.125% for the insulation value of the Gaziantep is a good value to be considered for a grid connected solar PV system in that particular location. For this particular study, the following information has been given to the software as a proposed power case for the energy model as shown in Table 2.
7. Results and discussion Through using the RETScreen software, the CO2 emission reduction from the proposed energy model has been examined. The RETScreen is used to determine the annual GHG emission reduction for the project compared to conventional technology based cases and the results are presented in terms of tons of CO2 per-year that will be equivalent to the emission reduction regardless of the actual gases composed in the emission, and this is achieved by converting CH4 and N2O to the equivalent CO2 Table 2 Proposed case power system. System type Power capacity Longitude and latitude Heating and cooling design value Earth temperature Capacity factor Electricity exported to the grid
Photovoltaic 500 kWp 37.82105° long., 37.120010° lat. 10° and 70° 25° 20.1% 881.5 MW h
Table 3 GHG emission reduction of 500 kWp SPV system, base case electricity system. Country region (Turkey-Gaziantep). Fuel type
GHG emission factor (tCO2/ MW h)
Coal 1.059 Oil 0.779 Natural gas 0.376
Annual GHG emission reduction (tCO2)
Equivalent of barrel of crude oil not consumed
933.2 686.9 331.4
2170 159 771
Fig. 3. Financial analysis with the effect of GHG emission reduction income from coal on annual savings and incomes.
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Fig. 4. Financial analysis with the effect of GHG emission reduction income from oil on annual savings and incomes.
Fig. 5. Financial analysis with the effect of GHG emission reduction income from natural gas on annual savings and incomes.
Table 4 Financial input parameters [27]. GHG reduction credit rate Inflation rate Project life Debt ratio Debt term Debt term Total initial cost
Table 5 Financial analysis result without emission reduction price [25]. USD/tCO2 736.5 9.0% 25 years 70% 4.50% 7 years USD 702,000
emission in terms of their GWP and it also adjusts the reduction to account for transmission and distribution losses and GHG credit if any [24]. The GHG emission factors of three different types of fuel are available in the software. Table 3 shows the emission factors based on the available fuel type in RETScreen software. Analysis of the result shows that the project annually supply 881.475 MW h/year of electricity. And also this 500 kWp PV system serves as a means of reducing 933.2, 686.9, or 331.4 tons of greenhouse gas emission to the atmosphere when compared with
Total annual cost and debt payment Total annual savings and income Pre-tax IRR – equity Pre-tax IRR – asset Simple payback Equity payback
USD 83,391.00 USD 124,288.00 44.2% 21.9% 5.6 years 3.2 years
the same amount of electricity generated using coal, oil or natural gas respectively as the energy source. With the current feed-intariff of the country, it is interesting to note that the project has a simple payback period of 5.6 years only as shown in Table 5. This is almost less than one quarter of the project life of 25 years [24]. Also the project has a good internal rate of return. Thus, the project can be considered desirable to be implemented since it is proven to be environmentally beneficial and financially viable and profitable.
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Considering the emission factor presented in Table 3, the annual GHG emission reduction and the number of barrel of crude oil saved, it is evident that the reduction in the emission could reach a higher rate if the energy generation from PV could be of higher percentage in the electricity generation sector. This can only be possible if government can provide incentives for the development of renewable PV plants, which could serve as a means of encouraging private investors. Incentives could also result in a huge investment in the sector and consequently, large emission reduction of the GHG. The income generated from the GHG reduction of the solar PV system is very high as it accounted for averagely 537 Euro equivalent to 736.5 USD per ton of CO2 in Germany from 2006 to 2010 [26]. A clear effect of GHG emission reduction income could be seen in the financial analysis of the solar PV system as shown in Figs. 3–5. To financially analyze the system, the following data have been given to the RETScreen as financial input parameters as shown in Table 4 [27].
8. Conclusion This paper estimates the annual GHG or CO2 emission reduction capacity of grid-connected solar PV system in Gaziantep city of Turkey which has been compared with “equivalent of barrel of crude oil not consumed” using RETScreen software. It is concluded that the emission reduction capacity of the PV system is reasonable and it should be highly recommended as one of the major tool in CO2 emission reduction. But increasing the share of the solar PV system can only be achieved if there is adequate financial incentive provided by the government [26]. Government should lay down certain legislations that will ease the procedures followed for construction of generation facilities. This is because the complex procedures in obtaining the permits for the construction of generation facilities with lower installed capacity is one of the major factor affecting the solar PV system construction. These measures will serve as a means of encouragement to the private investor; which will result in the large share of PV electricity generation plant as a consequent high CO2 emission reduction.
Acknowledgements The authors gratefully acknowledge Safar Al-Hilal for his constructive comments.
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