Investigation of carbon footprint effect of renewable power plants regarding energy production: A case study of a city in Turkey

ABSTRACT

This paper presents a carbon footprint investigation of renewable power plants in a city in Turkey. With a total of 71 licensed power plants, this area is significant in terms of energy production resources such as hydroelectric, wind, solar, and lignite. As of April 2021, it has 4401.17 MW of installed power, accounting for 4.87% of Turkey’s installed power and ranked third in terms of installed power cities. This city has 18 natural gas power plants, 3 lignite power plants, 33 hydroelectric (stream), 7 hydroelectric (dam) power plants, 2 solar, 2 coal, 2 wind, 1 waste heat, and 3 biomass power plants. However, all production technologies produce CO₂ and other greenhouse gases (GHGs), and emissions might be both direct and indirect. Once harmful gases are released into the atmosphere, they damage the ecosystem and all living things while also contributing to climate change. The Kyoto Protocol and the Paris Climate Agreement were signed to deal with climate change and propose a limitation on carbon emissions. Thus, countries have adopted some strategies to reduce their carbon footprint. For instance, Turkey is aiming to increase the share of domestic and renewable energy in electricity generation to reduce GHG emissions by up to 21% between 2020–2030. In this study, a carbon footprint effect analysis was carried out during electricity generation in a city with abundant renewable energy potential. According to the findings, it was determined that the renewable power plants successfully reduced the carbon footprint of the area as 3,500,794 tons CO₂, 3,024,120 tons CO₂, and 1,073,039 tons CO₂ for 2019, 2020, and 2021 (end of April), respectively.

Implications: The main aim of this study is to investigate a carbon footprint effect during electricity generation in a region (Kahramanmaraş, Turkey) with abundant renewable energy potential in terms of electricity generation. This area is significant in terms of energy production resources including hydroelectric, wind, solar, and lignite, with a total of 71 licensed power plants.

The key contributions of this research study are:

(1) The study of carbon footprint savings based on the electricity generation of this city was carried out for the first time in the literature.

(2) While generating electricity with renewable energy sources, it has been determined that an average of 3,500,794 tons CO2, 3,024,120 tons CO2, and 1,073,039 tons CO2 carbon footprint savings were accomplished for 2019, 2020, and 2021 (end of April), respectively.

(3) This study demonstrated that a city with abundant lignite potential emits a high amount of carbon footprint into the atmosphere while producing energy. By using lignite, 4,462,045 tons CO2, 3,952,348 tons CO2, and 1,140,975 tons CO2 were emitted for 2019, 2020, and 2021 (end of April), respectively.

(4) The study includes encouraging research on renewable energy investment in accordance with the Kyoto Protocols and the Paris Agreement for local governments and investors.

(5) The study sheds light on the distance Turkey has covered on the way to the 2030 targets in the fight against cli-mate change, regionally

Introduction

The demand for energy is being accelerated by the growing global population and rapidly developing technologies (Kerem and Kirbas 2021). Electrical energy is also crucial for countries’ economic and social development (Gorgulu 2019).

The electricity generation industry is one of the largest contributors to greenhouse gas (GHG) emissions in many countries (MacGill, Outhred, and Nolles 2006). All electricity generation technologies emit CO₂ and other GHGs into the atmosphere, both directly and indirectly. Emissions from the power plant during operation are considered direct, while emissions from other non-operational phases of the life cycle (LC) are considered indirect. Coal, gas, and oil-based nonrenewable energy technologies have the highest carbon footprint since they burn these fuels during operation. Hydroelectric, wind, solar, nuclear, wave/tidal, and biomass-based renewable energy technologies are considered low carbon as they do not emit CO₂ during operation. These technologies emit CO₂ at various phases of their LC which involves extraction, transportation, processing, building, maintenance, and decommissioning (Magaril et al. 2017; POST. Parlimentary Office of Science and Technology. Carbon Footprint of Electricity Generation 2006).

Toxic gases, especially CO₂, are released into the atmosphere, causing a greenhouse effect, increasing global warming, and causing global climate change (Florides and Christodoulides 2009). Climate change is a major global environmental issue that has the potential to endanger the world economy and may cause international conflict and political crisis with its effects on society and biodiversity (Lima et al. 2020). To overcome climate change, many countries have committed to reducing anthropogenic GHGs by signing the Kyoto Protocol of 1997 (Babiker 2005). The Paris Agreement was then taken as a critical step in the global response to the threat of climate change. It aims to keep the global average temperature rise below 2°C and limit it to 1.5°C relative to pre-industrial levels (Rogelj et al. 2017). On 24 May 2004, Turkey became the 189th party to join the agreement. On 16 February 2005, the Kyoto Protocol came into force. This agreement aims to make countries responsible for keeping GHGs emitted into the atmosphere and the anthropogenic impact on the climate system at a certain level. In addition, this agreement has become more effective in international emissions trading, technology, and capital movements. Turkey aims to reduce GHG emissions by up to 21% between 2020 and 2030 (MENR 2021g). Furthermore, according to the European Green Deal, the EU aims to reduce GHG emissions by at least 55% by 2030 and zero GHG emissions by 2050 (EU. European Union 2021). Some literature studies on GHGs emitted through electricity generation are given in Table 1.

Table 1. Some literature studies on GHGs emitted through electricity generation

Research Area	Definition	Country	Reference
Carbon footprint	The effect of an electricity storage operation and geographic location on GHG emissions from the electricity system was investigated	Great Britain	(Pimm et al. 2021)
Carbon footprint	The trends and situations regarding energy sources and GHG emissions in the Malaysian power generation mix were examined	Malaysia	(Latif et al. 2021)
Carbon footprint	The possibility of zeroing annual net carbon emissions from electricity generation was investigated on the Island of Crete	Greece	(Vourdoubas 2021)
Carbon footprint	The impact of a hydroelectric power plant on carbon emission was investigated	Turkey	(Bayazıt 2021)
Life cycle assessment	The GHG emissions from electricity sources were investigated	Canada	(Pereira and Posen 2020)
Life cycle assessment	The emissions of a supercritical coal-fired power plant were studied	Pakistan	(Rasheed et al. 2021)
Life cycle assessment	The GHG emissions in a two-stroke engine coupled with a 750 W electric generator designed to run on biogas were investigated	Indonesia	(Nindhia, McDonald, and Styles 2021)
Life cycle assessment	The GHG emissions associated with nuclear energy generation were studied	United Kingdom	(Pomponi and Hart 2021)
Life cycle assessment	The carbon emissions of a 49.5 MW wind farm in inner Mongolia were investigated	Mongolia	(Liu et al. 2021)
Life cycle assessment	A comparative emission study of the deployment of micro-scale renewable power generation devices in Alaska with the current method that uses diesel for electricity generation was undertaken	USA	(McCallum et al. 2021)
Life cycle assessment	The LC analysis of a neighborhood with zero GHG emissions was carried out	Norway	(Lausselet, Lund, and Brattebø 2021)
Life cycle assessment	GHG emissions in wind farms were investigated	Ethiopia	(Teffera et al. 2021)
Life cycle assessment	The emissions produced in the process of generating electricity from biomass were investigated	Mexico	(Parascanu et al. 2021)
Forecasting	GHG emissions from the Chinese coal-electricity chain were investigated using a bottom-up approach	China	(Li et al. 2021)
Forecasting	GHG emissions were forecasted based on the utilization of energy generation, deep learning, support vector machines, and artificial neural networks	Turkey	(Bakay and Ağbulut 2021)
Forecasting	Different approaches to estimating hydroelectric reservoir emissions in the LC assessment were compared	Canada	(Levasseur et al. 2021)

In this paper, the carbon footprint research of renewable power plants in the Kahramanmaraş City of Turkey was investigated. With a total of 71 licensed power plants, this city was chosen for research since it is a significant city in terms of energy production resources such as hydroelectric, wind, solar, and lignite (at 2021). This city accounts for 4.87% of Turkey’s installed power and is the third-largest city in terms of installed power in the country. 18 natural gas, 3 lignite, 33 hydroelectric (stream), 7 hydroelectric (dam), 2 solar, 2 coal, 2 wind, 1 waste heat, and 3 biomass power plants have been licensed in this city. However, all production technologies emit CO₂ and other GHGs, which are released into the environment either directly or indirectly. Since these gases have adverse effects on global warming, environmental quality, and all living beings, in recent years, countries have adopted strategies to generate electricity with clean and eco-friendly renewable energy sources to reduce their carbon footprint.

The main aim of this study is to investigate a carbon footprint effect during electricity generation in a city with abundant renewable energy potential.

The key contributions of this research study are:

• The investigation of carbon footprint savings based on the electricity generation of this city was carried out for the first time in the literature with this study.

• While generating electricity with renewable energy sources, it has been determined that an average of 3,500,794 tons CO₂, 3,024,120 tons CO₂, and 1,073,039 tons CO₂ carbon footprint savings were accomplished for 2019, 2020, and 2021 (end of April), respectively.

• This study demonstrated that a city with abundant lignite potential emits a high amount of carbon footprint into the atmosphere while producing energy. By using lignite, 4,462,045 tons CO₂, 3,952,348 tons CO₂, and 1,140,975 tons CO₂ were emitted for 2019, 2020, and 2021 (end of April), respectively.

• The study includes encouraging research on renewable energy investment in accordance with the Kyoto Protocols and the Paris Agreement for local governments and investors.

• The study sheds light on the distance Turkey has covered on the way to the 2030 targets in the fight against climate change, regionally.

The rest of the paper continues as follows. The carbon footprint concept is described in Section 2. An overview of energy resources and energy generation in Turkey and Kahramanmaraş City are given in Section 3. The carbon footprint assessment of power plants in Kahramanmaraş City is explained with methodology in Section 4. Results and discussions are presented in Section 5. Conclusions and recommendations are presented in Section 6.

Carbon footprint

The carbon footprint is a measure of the influence of human activity on the environment, with a focus on climate change impacts (Ciocan and Valter 2009). A carbon footprint is the total quantity of CO₂ and other GHGs released by a process or product during its entire LC. It can be expressed in gCO₂ eq/kWh (grams of CO₂ equivalent per kilowatt-hour of generation) (POST. Parlimentary Office of Science and Technology. Carbon Footprint of Electricity Generation 2006).

Carbon footprint emissions can occur both directly and indirectly caused by activity and are accumulated over the LC of the product (Wiedmann and Minx 2007). That is, while the carbon footprint can occur directly during the operation of the power plant, it also occurs at other non-operational stages of the LC. Fossil-fueled technologies such as coal, oil, and gas have a large carbon footprint since these fuels are used during operation. Non-fossil fuel-based technologies such as wind, solar, hydro, nuclear, wave/tidal, and biomass are called low carbon since they do not emit CO₂ during their operation. These technologies, on the other hand, cannot be described as “carbon-free.” CO₂ emissions occur during various phases of their LC, including during extraction, transportation, processing, construction, maintenance, and decommissioning, despite the fact that they do not occur during energy generation (POST. Parlimentary Office of Science and Technology. Carbon Footprint of Electricity Generation 2006). The LC of carbon emissions for electricity generation technologies is given in Figure 1.

Figure 1. Life cycle (LC) of carbon emissions for electricity generation technologies (POST. Parlimentary Office of Science and Technology. Carbon Footprint of Electricity Generation 2006).

The LC of carbon footprints according to source types are given in Table 2. According to Table 2, fossil-based sources such as coal, oil, and gas have high carbon emissions, non-fossil-based sources such as solar, biomass, wave/tidal, hydroelectric, wind, and nuclear sources have low carbon emissions (POST. Parlimentary Office of Science and Technology. Carbon Footprint of Electricity Generation 2006).

Table 2. Life cycle (LC) of carbon footprints according to source types

Carbon Emissions	Source Types	LC Carbon Footprint (gCO2/kWh)
High carbon emissions	Coal	>1000
	Oil	650
	Gas	500
Low carbon emissions	Solar	58 (common)
		35 (thin-film technologies)
	Biomass	93 (miscanthus)
		25 (wood-chip)
	Wave and tidal	25–50
	Hydroelectric	10–30 (dam)
		5 (very small reservoirs)
	Wind	4.64 (onshore)
		5.25 (offshore)
	Nuclear	5

In 2019, the energy sector accounted for 72% GHG emissions, followed by agriculture (14%), industrial processes and product usage (11%), and waste (3%) (TSI. Turkish Statistical Institute 2021). GHG emissions (million ton CO₂ equivalent) by sectors in Turkey are given in Table 3.

Table 3. Greenhouse gas (GHG) emissions (million ton CO₂ equivalent) by sectors in Turkey (TSI. Turkish Statistical Institute 2021)

Sectors	1990	2000	2010	2015	2016	2017	2018	2019
Energy	140	216	287	341	360	380	373	364
Industrial processes and product usage	223	26	48	57	61	64	66	56
Agriculture	46	42	44	56	59	63	65	68
Waste	11	14	20	19	19	18	18	17
TOTAL	217	299	399	473	499	525	523	506

GHG emissions (million ton CO₂ equivalent) in Turkey are given in Figure 2. Total GHG emissions continued to increase from 1990 to 2017, however, they decreased in 2018 and 2019. While the highest GHG emissions were produced in 2017 with 525 million tons of CO₂, the lowest figure was observed in 1990 with 219.6 million tons of CO₂. (CO₂: carbon dioxide, CH₄: methane, N₂O: nitrous oxide, F-gases: fluorinated gases) (TSI. Turkish Statistical Institute 2021).

Figure 2. Greenhouse gas (GHG) emissions (million ton CO₂ equivalent) in Turkey.

Overview of energy generation in Turkey

In the last two decades, Turkey’s rapid economic and population growth has increased both energy demand and import dependency (IEA. International Energy Agency 2021). Turkey is a foreign-dependent country that imports 74% of its energy (MFA 2021). For this reason, Turkey has restructured its energy system to rationalize increasing energy demands, lower energy prices for consumers, and reduce the number of imports. Turkey has tripled its electricity production with renewable resources in the last ten years. It also plans to commission its first nuclear power plant in 2023 to meet its energy demand (IEA. International Energy Agency 2021).

The ”National Energy Efficiency Action Plan (2017–2023),” Turkey’s first energy efficiency action plan, came into effect in 2018. Turkey aims to save 23.9 million tons of oil equivalent (MTEP) cumulatively by investing USD 10.9 billion until 2023, thus, observing a 14% reduction in primary energy consumption by 2023. Furthermore, a saving of USD 30.2 billion is expected until 2033 (MENR 2021g).

The distribution of licensed electricity generation in Turkey for 2021 is given in Table 4 (EMRA 2021). Electrical energy production was 26,500,154 MWh, 23,607,942 MWh, 27,071,150 MWh, and 25,013,328 MWh for January, February, March, and April, respectively. Thus, the highest production was observed in March. In addition, the largest production for January was natural gas with 8,331,236 MWh, while fuel oil was the lowest with 25,872 MWh. The largest production in February belongs to natural gas again, however, the production amount decreased by 20.39% compared to the previous month to 6,632,169 MWh. In March, natural gas continued to maintain its highest production rate and increased by 22.79% compared to the previous month to 8,143,709 MWh. Having the highest production rate in April, natural gas decreased to 5,649,660 MWh with a decrease of approximately 30.63% compared to the previous month.

Table 4. Distribution of licensed electricity generation in Turkey, 2021

Source	January		February		March		April
	Energy Generation (MWh)	Rate (%)	Energy Generation (MWh)	Rate (%)	Energy Generation (MWh)	Rate (%)	Energy Generation (MWh)	Rate (%)
Natural gas	8,331,236	31.44	6,632,169	28.09	8,143,709	30.08	5,649,660	22.59
Coal (imported)	5,471,628	20.65	5,400,518	22.88	4,557,011	16.83	3,379,419	13.51
Hydroelectric	4,304,562	16.24	4,005,928	16.97	6,197,431	22.89	8,055,298	32.20
Lignite	3,430,982	12.95	3,094,150	13.11	3,461,199	12.79	3,457,637	13.82
Wind	2,876,851	10.86	2,495,807	10.57	2,490,362	9.20	2,330,925	9.32
Geothermal	976,242	3.68	869,126	3.68	984,037	3.64	916,455	3.66
Biomass	537,330	2.03	528,442	2.24	584,521	2.16	571,801	2.29
Coal	331,188	1.25	289,140	1.22	318,734	1.18	298,283	1.19
Asphaltite	170,635	0.64	198,092	0.84	221,520	0.82	224,337	0.90
Solar	43,627	0.16	69,323	0.29	84,276	0.31	102,824	0.41
Fuel oil	25,872	0.10	25,248	0.11	28,351	0.10	26,690	0.11
TOTAL	26,500,154	100	23,607,942	100	27,071,150	100	25,013,328	100

The distribution of licensed electricity generation (MWh) in Turkey, 2021 is given in Figure 3 (EMRA 2021). Energy production with fuel oil was realized at the highest level in March with 28,351 MWh. Solar energy production has continued to increase per month since January, and the highest generation was realized in April with 102,824 MWh. Energy generation with asphaltite has continued to increase per month since January and the highest generation was realized in April with 224,337 MWh. Energy generation with coal was realized at the highest level in January with 331,187.90 MWh. The highest amount of biomass used occurred in March with 584,521 MWh for energy generation. The highest geothermal use occurred in March with 984,037 MWh. The highest wind use occurred in January with 2,876,851 MWh, however, this decreased with each subsequent month. Energy generation with lignite was realized at the highest level in March with 3,461,199 MWh. Hydroelectric energy generation increased rapidly in March and April compared to the previous months, with the highest generation of 8,055,297 MWh occurring in April. Energy generation with coal (imported) was realized at the highest level in January with 5,471,628 MWh, and it continued to decrease with each subsequent month. The highest natural gas was used in January with 8,331,236 MWh.

Figure 3. Distribution of licensed electricity generation (MWh) in Turkey, 2021.

The distribution of licensed electricity generation (%) in Turkey, April 2021 is given in Figure 4 (EMRA 2021). Hydroelectric was the highest rate of energy production at 32.20%, followed by natural gas at 22.59%, lignite at 13.82%, coal (imported) at 13.51%, wind at 9.32%, geothermal at 3.66%, biomass at 2.29%, coal at 1.19%, asphaltite at 0.90%, solar at 0.41%, and fuel oil at 0.11%.

Figure 4. Distribution of licensed electricity generation (%) in Turkey, April 2021.

Energy sources and power plants of Kahramanmaraş city

Kahramanmaraş City is the 11th largest city of Turkey with an area of 14,327 km². The central district is at an altitude of 568 m above sea level. Mediterranean climate is observed in the south of the city and continental climate is observed in the north, in addition, summers are hot and winters are cold (Kahramanmaraş Metropolitan Municipality 2021). The geographical location of Kahramanmaraş City is given in Figure 5.

Figure 5. Geographical location of Kahramanmaraş City, Turkey.

Biomass

This city has agriculturally suitable land. The city produces a total of 2,393,951 tons of cereals, vegetables, and fruits, including 509,822 tons of corn, 503,948 tons of sugar beet, 443,557 tons of wheat, and 90,284 tons of barley. On the other hand, 1,048,483 tons of waste is produced and the energy equivalent is approximately 439,717 tons of oil equivalent (TOE). There are a total of 2,559,683 animals in this city, and 2,537,995 tons of animal waste is produced annually and its energy equivalent is 32,794 TOE. The energy equivalence of the region’s (Hatay, Kahramanmaraş, Kilis and Gaziantep) forest waste approximately is 8421 TOE. Additionally, the energy equivalence of the city’s organic waste is 35,170 TOE per year. Energy equivalence amounts of wastes considered as Kahramanmaraş City biomass potential are given in Table 5 (BEPA. Turkey Biomass Energy Potential Atlas 2021).

Table 5. Energy equivalence amounts of wastes considered as Kahramanmaraş City biomass potential

Waste Types	Yearly Energy Equivalent (TOE)
Plant	439,717
Animal	32,794
Forest	8421
Urban	35,170
TOTAL	516,102

Wind

In Turkey, it has been determined that 5 MW wind power plants can be constructed per km² in areas 50 m above ground level and with wind speeds above 7.5 m/s (MENR 2021g). The average wind speed of Kahramanmaraş City is 4 m/s, the average power density is 169,849 W/m², and the average capacity factor is 20.6% (MENR 2021g). The annual average wind speed distribution of Kahramanmaraş City (at 100 m) is presented in Figure 6 (MENR 2021g).

Figure 6. Annual average wind speed distribution of Kahramanmaraş City (at 100 m).

Hydroelectric

The overall water potential of Kahramanmaraş City is 9614.8 hm³/year, with 9000 hm³/year above ground and 614.8 hm³/year underground. It receives an average of 620.6 mm of precipitation annually. There are 8 dams and 13 ponds in operation. The total installed power of the hydroelectric power plants in operation is 1707.92 MW, while the power plants under construction have a total installed power of 11.91 MW (SHW. General Directorate of State Hydraulic Works 2021). The total area of the dam lakes of this city, which is rich in reservoirs is 105.31 km² (Kahramanmaraş Metropolitan Municipality 2021).

Solar

Kahramanmaraş City is located in the south of Turkey. The solar potential of Kahramanmaraş City is given in Figure 7 (MENR 2021g). As seen in Figure 7, the total amount of solar radiation increases from north to south, and the annual solar potential of Kahramanmaraş City is 1650–1700 KWh/m².

Figure 7. Solar potential of Kahramanmaraş City.

The solar energy generation potential considering PV types and panel space in Kahramanmaraş City, is given in Figure 8 (MENR 2021g). The generated energy varies according to PV types and panel areas, as seen in Figure 8. Monocrystalline silicon PV installed on a 100 m² space can generate roughly 27,000 KWh of energy per year, and polycrystalline silicon cell solar panels can generate roughly 23,900 KWh, in this city.

Figure 8. Solar energy generation considering the PV types and panel space in Kahramanmaraş City (MENR 2021g).

Lignite

Turkey has 19,320,000,000 tons of lignite reserves. Kahramanmaraş (Afşin-Elbistan) has 5,157,340,000 tons of lignite reserves, which corresponds to approximately 26.7% of the total of the country. Furthermore, since 79% of the country’s lignite reserves have a calorific value of less than 2500 kcal/kg, they are primarily utilized in thermal power plants (MRE. Mineral Research and Exploration General Directorate 2021). The boiler used in the power Afşin-Elbistan B thermal power plant is a Benson tower type and is approximately 110 m high. The boiler has a maximum steam production capacity of 1100 tons/h at 177 bar and 538°C (AEBTP 2021).

The total number of power plants in 2019, 2020, and 2021 are 68, 71, and 71, respectively. There are power plants in which the number of facilities has remained constant across the three years: hydroelectric (stream) (33), hydroelectric (dam) (7), wind (2), waste heat (1), natural gas (18), lignite (3), and coal (2). Furthermore, there were also power plants in which the number of facilities fluctuated over the three years, including biomass (2) for 2019 and (3) for 2020 and 2021, and solar (2) for 2020 and 2021. (Data of plant items, installed power (MW), and energy generation (MWh/year) for 2019, 2020, and 2021 have been officially obtained from the Republic of Turkey Energy Market Regulatory Authority (EMRA)).

The distribution of the licensed power plants of Kahramanmaraş City by resource and installed power is given in Figure 9.

Figure 9. Distribution of the licensed power plants of Kahramanmaraş City by resource and installed power.

The installed power and annual power generation of the licensed power plants of Kahramanmaraş City are given in Table 6. In 2019, 2020, and 2021, hydroelectricity (stream + dam), which is a renewable energy source, had the highest generation accounting for 4,698,002 MWh, 4,005,213 MWh, and 1,403,809 MWh, respectively.

The distribution of Kahramanmaraş City’s licensed power plants energy generation (MWh) by resource in 2021 is given in Table 7. Total energy generation has continued to increase since January. The highest generation was realized in April with 770,697 MWh. In January, lignite had the largest value in generation with 267,358 MWh. Hydroelectric (stream + dam) had the biggest value in generation in February, March, and April. These values were 341,736 MWh, 408,972 MWh, and 391,950 MWh for February, March, and April, respectively.

Table 7. Distribution of Kahramanmaraş City’s licensed power plants energy generation (MWh) by resource, 2021

Sources	January 2021	February 2021	March 2021	April 2021
	Energy Generation (MWh)	Energy Generation (MWh)	Energy Generation (MWh)	Energy Generation (MWh)
Natural gas	32,615	26,590	37,966	36,697
Lignite	267,358	212,136	245,677	302,726
Hydroelectric (stream)	78,698	127,896	193,198	197,545
Hydroelectric (dam)	182,455	213,840	215,774	194,405
Solar	1895	2709	3072	3356
Coal	11,704	10,543	12,059	11,839
Wind	17,947	15,175	21,395	18,904
Waste heat	2049	2224	3157	2991
Biomass	2280	2046	2439	2236
TOTAL	597,000	613,157	734,738	770,697

The maximum energy generation with natural gas was realized in March at a level of 37,966 MWh, while the minimum generation was realized in February with 26,590 MWh. The highest lignite use occurred in April with 302,726 MWh, and the least use with 212,136 MWh occurred in February. The highest hydroelectric (stream + dam) use occurred in March with 408,972 MWh, while the least use occurred in January with 261,153 MWh for energy production. Solar energy generation has continued to increase since January, with the highest generation realized in April with 3356 MWh, and the lowest level realized in January with 1895 MWh. Energy generation with coal was realized at the highest level in March with 12,059 MWh, with February generating the least amount with 10,543 MWh. The highest wind use occurred in March with 21,395 MWh, and the least use occurred in February with 15,175 MWh. The highest waste heat use occurred in March with 3157 MWh, and the least with 2049 MWh in January. Energy generation with biomass was realized at the highest level in March with 2439 MWh and the lowest generation was realized in February with 2046 MWh.

The distribution of billed electricity consumption and consumer type of Kahramanmaraş City (April 2021) is given in Table 8 (EMRA 2021). The highest electricity consumption occurred in the industrial sector with 225,033 MWh, constituting approximately 68% of the total consumption. The least consumption occurred in agricultural irrigation with 1729 MWh, constituting approximately 1% of the total consumption.

Table 8. Distribution of billed electricity consumption and consumer type of Kahramanmaraş City (April 2021) (EMRA 2021)

Lighting (MWh)	Residence (MWh)	Industry (MWh)	Agricultural Irrigation (MWh)	Business (MWh)	Total (MWh)	Part in Turkey (%)
6,421	52,749	225,033	1,729	43,587	329,520	1.61

The distribution of energy production (MWh) of Kahramanmaraş City’s licensed power plants according to resources for 2021 are given in Figure 10.

Figure 10. Distribution of energy production (MWh) of Kahramanmaraş City’s licensed power plants according to resources (2021).

The distribution of energy production (%) of Kahramanmaraş City’s licensed power plants according to resources for 2021 are given in Figure 11.

Figure 11. Distribution of energy production (%) of Kahramanmaraş City’s licensed power plants according to resources, 2021.

Methodology

It is emphasized in Section 2 that although no GHG emissions are released to nature while energy is generated using renewable energy sources, GHG emissions occur during LC stages such as extraction, transportation, processing, construction, maintenance, and decommissioning (POST. Parlimentary Office of Science and Technology. Carbon Footprint of Electricity Generation 2006). Illustration of the licensed power plants of Kahramanmaraş City is shown in Figure 12.

Figure 12. Illustration of the licensed power plants of Kahramanmaraş City.

In this section, the carbon footprint savings of Kahramanmaraş City licensed renewable energy power plants (hydroelectric (stream + dam), solar, wind, and biomass) during electricity generation are compared to fossil-based power plants.

Firstly, the carbon footprint saving research began with the determination of the energy generation values using renewable energy per year in the city. Quantities of energy generation using renewable energy at Kahramanmaraş City’s licensed power plants are given in Table 9. The highest amount of energy generated with renewable energy was 4,884,829 MWh in 2019. This value decreased to 4,219,702 MWh in 2020, a fall of about 14%. The generation is still continuing, and 1,497,264 MWh has been produced until the end of April 2021.

Secondly, the carbon footprint values which are the emission equivalents of each kWh were calculated in gCO₂ using sources in Table 2. It indicates that there are two distinct categories of carbon emissions described as high and low. Fossil-based sources such as coal, oil, and gas constitute high carbon emissions. The carbon footprint values for coal, oil, and gas are >1000 gCO₂/kWh, 650 gCO₂/kWh, and 500 gCO₂/kWh, respectively. However, solar, biomass, wave and tidal, hydroelectric, wind, and nuclear sources constitute low carbon emissions. These carbon footprint values are 58 gCO₂/kWh (common) and 35 gCO₂/kWh (thin-film technologies) for solar, 93 gCO₂/kWh (miscanthus) and 25 gCO₂/kWh (wood-chip) for biomass, 25–50 gCO₂/kWh for wave and tidal, 10–30 gCO₂/kWh (dam) and 5 gCO₂/kWh (very small reservoirs) for hydroelectric, 4.64 gCO₂/kWh (onshore) and 5.25 gCO₂/kWh (offshore) for wind, and 5 gCO₂/kWh for nuclear (POST. Parlimentary Office of Science and Technology. Carbon Footprint of Electricity Generation 2006). However, in this research study, since electricity energies are not produced with fossil resources and no emissions are released to nature, they are considered as carbon footprint savings and are given in Table 10.

Table 10. Annual carbon footprint savings

Year	Total Renewable Energy Generation (MWh)	Carbon Footprint Saving Compared to Coal (tCO2)	Carbon Footprint Saving Compared to Oil (tCO2)	Carbon Footprint Saving Compared to Gas (tCO2)	Average Carbon Footprint Saving Compared to Coal + Oil + Gas (tCO2)
2019	4,884,829	4,884,829	3,175,139	2,442,414	3,500,794
2020	4,219,702	4,219,702	2,742,806	2,109,851	3,024,120
2021 (end of April)	1,497,264	1,497,264	973,222	748,632	1,073,039

According to Table 10, a total 4,884,829 MWh of energy was generated with renewable energy sources in 2019. However, if this energy was generated using fossil-based sources, 4,884,829 tons CO₂, 3,175,139 tons CO₂, and 2,442,414 tons CO₂ emissions would have been observed for coal, oil, and gas, respectively. Additionally, on average, 3,500,794 tons CO₂ emissions would occur (this is the average tCO₂ of coal, oil, and gas). Similarly, a total 4,219,702 MWh of energy was generated with renewable energy sources in 2020. However, if this energy was generated using fossil-based sources, 4,219,702 tons CO₂, 2,742,806 tons CO₂, and 2,109,851 tons CO₂ emissions would have been observed for coal, oil, and gas, respectively. On average, 3,024,120 tons CO₂ emissions would occur (this is the average tCO₂ of coal, oil, and gas). Finally, a total 1,497,264 MWh of energy was generated with renewable energy sources in 2021. However, if this energy was generated using fossil-based sources, 1,497,264 tons CO₂, 973,222 tons CO₂, and 748,632 tons CO₂ emissions would have been observed for coal, oil, and gas, respectively. On average, 1,073,039 tons CO₂ emissions would occur (this is the average tCO₂ of coal, oil, and gas). However, these energies were generated using renewable energy sources and were considered as a carbon footprint saving.

Results and discussion

In 2019, electricity generation using renewable energy sources was 4,884,829 MWh and the average carbon footprint saving was calculated as 3,500,794 tons CO₂. The following year (2020), electricity generation using renewable energy sources declined by around 14% to 4,219,702 MWh, while the average carbon footprint was reduced by approximately 14%to 3,024,120 tons of CO₂. Energy generation is still continuing on by the end of April 2021, resulting in 1,497,264 MWh of energy produced with renewable energy sources and 1,073,039 tons of CO₂ saved on average.

The average carbon footprint savings and renewable energy generation of Kahramanmaraş City’s licensed power plants are shown in Figure 13.

Figure 13. The average carbon footprint savings and renewable energy generation of Kahramanmaraş City’s licensed power plants.

The total carbon footprint and carbon footprint saving of Kahramanmaraş City’s licensed power plants are given in Figure 14. In 2019, while the amount of carbon footprint resulting from fossil-based sources was 4,462,045 tons CO₂, the carbon footprint saving obtained by using renewable energies was 3,500,794 tons CO₂. In 2020, the carbon footprint was decreased by approximately 11% to 3,952,348 tons CO₂ compared to the previous year (2019), while the carbon footprint saving amount was decreased by approximately 14% to 3,024,120 tons CO₂. In 2021 (end of April), energy generation is still continuing, thus the carbon footprint amount is 1,140,975 tons CO₂ and carbon footprint saving is 1,073,039 tons CO₂.

Figure 14. Total carbon footprint and carbon footprint saving of Kahramanmaraş City’s licensed power plants.

According to this study, it has been determined that a city with a high lignite potential releases a large amount of CO₂ into the atmosphere while generating energy. It is undesirable and unacceptable in terms of environment and life quality. However, this city has plenty of renewable energy potential such as solar, wind, and biomass waiting to be exploited. On the other hand, for the first time in the literature, this study has demonstrated that carbon footprint savings were achieved while generating energy with the city’s current renewable energy power plants. It is clear that increasing the number of installed renewable power plants will result in a reduction in carbon emissions.This study also highlights Turkey’s regional progress on the road to 2030 targets in combating climate change, by drawing attention to renewable energy investments in accordance with the Kyoto Protocols and the Paris Agreement for local governments and investors.

Morever, the accuracy of energy estimation studies is of great importance due to some reasons such as performing the energy unit costs, efficient energy market, minimizing the risks of overloading the transformer centers, and so on. However, the accuracy rates vary depending on the type of energy and the estimation models. The predictability of electrical power generated from renewable energy sources such as solar, biomass and hydropower is more reliable than wind power. Because the wind has a random and discrete structure, which complicates the energy estimation and complicates its predictability in terms of energy production (Kerem and Saygin 2019; Kerem, Saygin, and Rahmani 2021; Saygin and Kerem 2017).

Furthermore, the construction of any power plant is a costly and time-consuming operation. All production technologies produce CO₂ or GHG and release it into the atmosphere either directly (nonrenewable power plants) or indirectly (renewable power plants). In addition, whether it is a renewable or nonrenewable power plant, it is possible to discuss the intervention in the living spaces of living things in both cases. The protection of the environment and the habitats of all living things should be among the priorities. For these reasons, all aspects of the power plants that are planned to be constructed, such as production technologies, locations, habitat effects, and fuel types, should be evaluated at an optimal level before investments are made.

To my expertise, no other comprehensive study on the carbon footprint impact of renewable power plants has been conducted. It has been observed that most of the studies focus on carbon footprint analysis, the LC analysis of one or more power plants, and forecasting. Thus, it is hard to compare this study with any in the literature.

According to some carbon footprint studies, Bayazıt (Bayazıt 2021) investigated the effect of a hydroelectric power plant on carbon emissions. He determined that annual 408,534 tons CO₂ carbon footprint savings of were achieved. Pimm et al. (Pimm et al. 2021) examined the impact of an electricity storage operation and its location on GHG emissions from the electricity system. They found a difference of 741 gCO₂/kWh between storage techniques, which is roughly equivalent to the reduction in emissions per unit achieved by equipping it with carbon capture and storage. Vourdoubas (Vourdoubas 2021) calculated annual carbon emissions from electricity generation on the Island of Crete as 3.22 tons CO₂.

According to some LC studies, Liu et al. (Liu et al. 2021) investigated the LC of carbon emissions of a 49.5 MW wind farm. They determined the carbon footprint of the wind farm in the grassland area was 18,701 tons CO₂, with the highest rate occurring during the construction phase accounting for 56.74%. They concluded that the stages of production, disposal, transportation, and operation accounted for 28.18%, 12.08%, 2.76%, and 0.24%, respectively. They also determined the carbon footprint of material recycling was 18,727 tons CO₂. Al-Behadili and El-Osta (Al-Behadili and El-Osta 2015) investigated the LC of carbon emissions of a 1.65 MW wind turbine. They determined the emissions savings to be 445,638 kg/year of NO_x, 3,160,552 kg/year of SO₂, and 250,473,762 kg/year of CO₂.

Bakay and Ağbulut (Bakay and Ağbulut 2021) used deep learning (DL), support vector machines (SVM), and artificial neural networks (ANNs) to forecast GHG emissions based on energy generation. Levasseur et al. (Levasseur et al. 2021) compared different approaches to estimating hydroelectric reservoir emissions over the LC. They were quite successful in forecasting total GHG emissions using a DL. They obtained R², RMSE, MBE, rRMSE, and MAPE values of 0.998, 2.046, 0.419, 0.406, and 0.021%, respectively.

Conclusion and recommendation

Countries have adopted carbon footprint reduction strategies to deal with climate change. The Kyoto Protocol and the Paris Agreement might be seen as two major milestones in this context.

In this study, the carbon footprint investigation of renewable power plants in Kahramanmaraş City, Turkey was investigated. There are two main reasons for choosing this city as a research location. The first is that there are 71 licensed power plants in the city with high potential energy sources such as hydroelectric, solar, wind, and lignite, and the second is that the carbon footprint savings of renewable power plants in the city have yet to be investigated in the literature. In addition, this study is significant as it sheds light on the distance Turkey has covered in progressing toward the 2030 targets for combating climate change, regionally.

According to the findings, in 2019, Kahramanmaraş City’s carbon footprint from fossil sources was 4,462,045 tons CO₂, whereas the carbon footprint saving from renewable energy sources was 3,500,794 tons CO₂. In 2020, the carbon footprint was 3,952,348 tons CO₂, while the carbon footprint saving was 3,024,120 tons CO₂. In 2021 (end of April), while the carbon footprint was 1,140,975 tons CO₂, the carbon footprint saving was 1,073,039 tons CO₂. It is pleasing that the gap between carbon footprint emissions and carbon footprint savings is decreasing year by year.

The city has great renewable energy potential, including wind, solar, and biomass, that has yet to be assessed. By increasing their installed power and producing more energy, it is possible to achieve more carbon footprint savings. Thus, it is foreseen that a beneficial contribution can be made to the fight against climate change, both on a national and global scale.

Turkey also has a voluntary carbon market, however, it only accounts for a minor fraction of the global carbon market. There are currently 308 projects aiming to reduce GHG emissions over 20 million tons CO₂ (MEU 2021). Carbon trading, on the other hand, provides emission control and the development of clean technologies at less cost. However, efforts to establish an emissions trading system and transition to the compulsory market in Turkey are still ongoing (Eymirli 2021). Thus, it is anticipated that the establishment of an emissions trading system and mandatory market transition may increase carbon footprint savings.

In future works, the GHG emissions of LC of power plants should be investigated in Kahramanmaraş City.

Author contributions

A.K. is responsible for all stages of the article such as the idea, data gathering, writing—original draft preparation, methodology, and editing. All authors have read and agreed to the published version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Alper Kerem

Alper Kerem is an Electrical Electronics Engineer. He received his BSc, MSc, and PhD degrees from Gazi University, Ankara, Turkey. Currently, he works as an Asst. Prof. Dr at Department of Electrical Electronics Engineering at Kahramanmaraş Sütçü İmam University. His research fields are electric power plants, energy systems, power electronics, and electric vehicles.