Analysis of energy and exergy use of the Turkish residential–commercial sector

ARTICLE IN PRESS

Building and Environment 40 (2005) 641–655 www.elsevier.com/locate/buildenv

Analysis of energy and exergy use of the Turkish residential–commercial sector Zafer Utlua, Arif Hepbaslib, a

Turkish Land Forces NCO Vocational College, 10110 Balikesir, Turkey Department of Mechanical Engineering, Faculty of Engineering, Ege University, 35100 Bornova, Izmir, Turkey

b

Abstract This study presents the analysis of the energy and exergy utilization of the Turkish residential–commercial sector (TRCS) in the years of 2000 and 2020 and compares the results obtained with those of other countries available in the literature. This analysis is done based on the actual data for 2000, while the projected energy data for 2020 are used in the calculations. Total energy and exergy inputs are calculated to be 3527.20 PJ and 3469.62 PJ in 2000, while they are projected to be 12,898.51 PJ and 12,636.99 PJ in 2020, respectively. Annual fuel consumptions in space heating, water heating and cooking activities as well as electrical energy uses by appliances are determined for 2000, while they are forecasted from 2004 to 2020. The energy efficiency value for the TRCS is found to be 55.60% in 2000, and is expected to be 65.53% in 2020. The exergy efficiency value for that is obtained to be 8.02% in 2000, with a projected value of 10.07% in 2020. Turkey’s overall energy and exergy utilization efficiencies in the same years are also found to be 44.91% and 24.78% in 2000, with the projected values of 55.15% and 30.44% in 2020, respectively. The present study clearly indicates the necessity of the planned studies towards increasing exergy efficiencies in the sector studied and especially the critical role of policymakers in establishing effective energy-efficiency delivery mechanisms throughout the country. It may be concluded that the current methodology is useful for analyzing the sectoral energy and exergy utilization, giving energy saving opportunities. r 2004 Elsevier Ltd. All rights reserved. Keywords: Energy efficiency; Exergy efficiency; Energy use; Exergy use; Energy resources; Residential sector; Turkey

1. Introduction The importance of energy as an essential ingredient in economic growth as well as in any strategy for improving the quality of human life is well established. The energy policy agenda has changed significantly since the days of the 1973 and 1979 oil crises. Currently, it is possible to identify three policy themes relating to the energy sector. These are as follows [1]: (a) the traditional energy policy agenda relating to security of energy supply, (b) concern about the environmental impact of Corresponding author. Tel.: +90-232-388-400/1918-17; fax: +90232-388-8562. E-mail addresses: [email protected] (Z. Utlu), [email protected], [email protected] (A. Hepbasli).

0360-1323/$ - see front matter r 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.buildenv.2004.08.006

energy, its production, transformation and use, and (c) the trend towards liberalization and the enhancement of competition in energy markets, notably in the electricity and gas sectors. Energy is defined as the working capacity of a system. However, this explanation describes its physical characterization. From another point of view, namely energy efficiency, it can be defined as providing ‘‘money’’ which makes life comfortable. Briefly, we may suggest that energy may be shortly defined as money [2], even cash [3,4]. The exergy of an energy form or a substance is a measure of its usefulness or quality or potential to cause change [5]. Exergy is defined as the maximum work which can be produced by a system or a flow of matter or energy at it comes to equilibrium with a specified

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642

Nomenclature a D e ex Ex f H ke m P p Q q r T t W y Z

energy carrier number of people per dwelling unit share of electrical energy use specific exergy (kJ/kg) exergy (kJ) share of fuel use higher heating value (kJ/kg) kinetic energy (kJ/kg) mass (kg) pressure (Pa) rate of change of dwelling units per year heat transfer (kJ) quality factor of an energy carrier share of renewable energy use temperature (K) change of population per year shaft work, work (kJ) population number of dwelling units

Greek symbols
1


2 g

exergy (second law) efficiency (%) exergy grade function

Indices 0 c d e f h ke o p Q or orc r rc s sh W wh

dead state or reference environment cooking, component direct electrical fuel, first heating kinetic energy overall product heat overall residential overall residential–commercial renewable, region residential–commercial stream space heating work water heating

energy (first law) efficiency (%)

reference environment. Unlike energy, exergy is conserved only during ideal processes and destroyed due to irreversibilities in real processes [6]. Wall and Gong [7] summarized the historical development of the concept ‘‘exergy’’, while Cengel [8,9] also described the meaning of exergy in daily life. He writes: ‘‘Exergy can be viewed as the opportunities that we have and the exergy destruction as the opportunities wasted. The exergy of a person in daily life can be viewed as the best job that a person can do under specific conditions. The difference between the exergy of a person and the actual performance under those conditions can be viewed as the irreversibility or the exergy destruction.’’ A through understanding of exergy and the insights it can provide into the efficiency, environmental impact and sustainability of energy systems, are required for the engineer or scientist working in the area of energy systems and the environment [5]. Dincer [10] reported the linkages between energy and exergy, exergy and the environment, energy and sustainable development, and energy policy making and exergy in detail. He provided the following key points to highlight the importance of the exergy and its essential utilization in numerous ways: (a) it is a primary tool in best addressing the impact of energy resource utilization on the environment. (b) it is an effective method using the conservation of mass and conservation of energy principles together with the second law of

thermodynamics for the design and analysis of energy systems. (c) it is a suitable technique for furthering the goal of more efficient energy-resource use, for it enables the locations, types, and true magnitudes of wastes and losses to be determined. (d) it is an efficient technique revealing whether or not and by how much it is possible to design more efficient energy systems by reducing the inefficiencies in existing systems. (e) it is a key component in obtaining sustainable development. (f) it has a crucial role in energy policy-making activities. Residential energy consumption depends mainly on the available amounts of local resources, which are closely connected with the present rural economy and living standards [11]. Energy consumption for heating is too high in Turkey since buildings have almost no insulation. Energy use per unit of building area in Turkey could be reduced by nearly half through the application to all buildings of the new Heat Insulation Standards on building envelopes, issued in 2000. While existing buildings require 200–250 kWh/m2 [12], the new standards could bring requirements down to 100–150 kWh/m2. At current rates of building stock turnover, the estimated energy efficiency gains could take several decades to materialize [13]. In addition, the potential for improved energy efficiency in boilers and stoves used for space heating is great. For example, based on a study conducted in Izmir, which is by population the third biggest city in Turkey,

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during the 1995–1996 winter period, it was concluded that a fuel saving of up to 12% could be obtained through improvement of the inefficiencies of boilers [14]. The energy utilization of a country can be evaluated using exergy analysis to gain insights into its efficiency [15]. Actually, only a few of such analyses are available. The first one was applied by Reistad to the US in 1970, published in 1975 [16,17], while the most comprehensive one in terms of years appears to be Ayres et al.’s analysis of the US between 1900 and 1998, published in 2003 [18]. Based on earlier studies conducted in this field by many authors, the approaches used to perform the exergy analyses of countries may be grouped into two types, namely Reistad’s approach and Wall’s approach, as denoted by Ertesvag [16]. The first approach considers flows of energy carriers for energy use, while the second one takes into account all types of energy and material flows (see Ref. [16] for more detail). Reistad’s approach is followed in the analyses of Finland [19], Canada [20], Brazil [21], the Organization for Economic Co-operation and Development (OECD) countries, non-OECD countries, and the world [22], England [23], and Saudi Arabia [24–27]. Besides these, the analyses of Sweden [28–30], Ghana (adapted Ref. [14]), Japan [31], Italy [32] and Norway [33] follow Wall’s approach. As for studies performed on Turkey’s sectoral (commercial, residential, industrial and transportation) energy and exergy analyses, to date, 12 studies [15,34–44] were realized. Of these, 11 [15,34–43] followed Reistad’s approach [17], while the last one [44] utilized a methodology applied for quantitative determinations of patterns of energy use in industry based on a nation-wide survey to characterize the structure of overall energy use in the Turkish food, textile and cement sectors. The methodology used in this study for analyzing Turkey’s sectoral energy and exergy use is similar to that of Rosen and Dincer [15], who used Reistad’s approach [17] with several minor differences. Earlier studies conducted on the energy and exergy analyses of Turkey are based on the values of the past years. The present study analyzes energy and exergy use of the Turkish residential–commercial sector (TRCS) in 2000 first. It then makes projections for 2020 using the forecasted data. Finally, the results of this study are compared with those of other countries available in the literature. This analysis is also done based on the actual data for 2000, while the projected energy data for 2020 are used in the calculations.

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2.1. General relations used in the modeling 2.1.1. Energy and exergy utilization efficiencies Energy (first law) and exergy (second law) utilization efficiencies in %,
1 and
2 ; can be defined as follows, respectively:
1 ¼ ðEnergy in products=Total energy inputÞ 100 (1)
2 ¼ ðEnergy in products=Total energy inputÞ 100: (2) 2.1.2. Exergy of heat The amount of thermal exergy transfer associated with heat transfer Qr across a system boundary r at constant temperature T r is   (3) ExQ ¼ 1  ðT 0 =T r Þ Qr : 2.1.3. Exergy of work The exergy associated with work is ExW ¼ W :

(4)

2.1.4. Chemical exergy One of the most common mass flows are hydrocarbon fuels at near-ambient condition, and the specific exergy may be reduced to chemical exergy, which can be written as exf ¼ gf H f

(5)

where gf denotes the fuel exergy grade function, defined as ratio of fuel chemical exergy to the fuel higher heating value H f : Some typical values of H f ; gf and exf for the fuels encountered in the present study are listed in Table 2. Usually, the specific chemical exergy
f of a fuel at T 0 and P0 is approximately equal to H f : Natural gas has the highest chemical exergy value. 2.1.5. Heating Electric and fossil–fuel heating processes are taken to generate product heat Qp at a constant temperature T p either from electrical energy W e or fuel mass mf : The efficiencies for electrical heating and fuel heating are
1e;h ¼ Qp =W e

and


2e;h ¼ ExQp =ExW e


1f;h ¼ Qp =mf H f and


2f;h ¼ ExQp =mf
f

(6) (7)

and hence
2e;h ¼ ðð1  T 0 =T p ÞQp Þ=ðW e Þ

2. Modeling of energy and exergy use This section includes some of the key aspects of thermodynamics in terms of energy and exergy [15,24–27] as well as population and dwelling unit estimations [37,41,45,46] used in the modeling.

and
2f;h ¼ ðð1  T 0 =T p ÞQp Þ=ðmf gf H f Þ
2e;h ¼ ð1  T 0 =T p Þ
1e;h

and

ð8Þ


2f;h ¼ ð1  T 0 =T p Þ
1f;h (9)

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where double subscripts indicate the processes in which the quantity represented by the first subscript is produced by the quantity represented by the second; e.g., the subscripts h, e, f, means heating electricity with fuel. 2.1.6. Work production Electric and fossil–fuel work production processes produces shaft work W. The efficiencies for shaft work production from electric and fossil fuels are as follows:
1e;w ¼ W =W e W


2e;w ¼ Ex =Ex

and We


1f;w ¼ W =mf H f

(10)

¼ W =W e ¼
1e;w

where yn is the population of the year assumed, yn1 is the population of the year known and t is the rate of change of population per year. The number of people per dwelling unit is computed by Du ¼ yn =Z n

(15a)

where Zn is the number of dwelling units of the year known. The dwelling unit of the year assumed is calculated from Z nþ1 ¼ Zn ð1 þ pÞ

(15b)

where p is the rate of change of dwelling unit per year.

and
2f;w ¼ ExW =mf H f ¼ W =ðmf gf H f Þ ¼
1f;w =gf :

ð11Þ 3. Results and discussion

2.1.7. Kinetic energy production The efficiencies for the fossil fuel-driven kinetic energy production processes, which occur in some devices in the transportation sector and which produces a change in kinetic energy Dke in a stream of matter ms ; are as follows:
1f;ke ¼ ms Dkes =mf H f

(12)


2f;ke ¼ ms Dkes =mf
f ¼ ms Dkes =ðmf gf H f Þ ¼
1f;ke =gf;ke : (13) 2.2. Population and dwelling unit estimations In this study, the values for populations, dwelling units, total energy and exergy inputs to the whole Turkey as well as the Turkish residential–commercial sector in 2000 are determined first using the data given in references [37,41,45,46]. Population and people per dwelling unit are then projected. By the help of these results, the number of the dwelling units is determined, as explained below. The figures of populations and dwelling units from 2005 to 2020 are projected by the following equations: yn ¼ yn1 ð1 þ tÞ

(14)

The values for populations, dwelling units and energy/exergy consumptions over the period from 2000 to 2020 are summarized in Table 1, while energy and exergy inputs for the same period according to energy carriers are illustrated in Table 2. By 2020, Turkey’s population and dwelling unit are estimated to be 85,554,317 and 22,192,965, respectively [37]. As can be seen in these tables, total energy and exergy inputs to the Turkish sector were 3527.20 and 3469.62 PJ in 2000, respectively, while they are expected to be 12,898.51 and 12,636.99 PJ in 2020, respectively. Of total energy input, 35.05% was produced in 2000. It is also projected that 25% of total energy input will be produced in 2020, while the rest will be met by imports. In 2020, of 11 energy sources, hard coal is expected to have the biggest share with 29.07%, followed by natural gas with 24.40%, petroleum with 21.90%, and lignite with 12.56%. In 2020, renewable energy source production is projected to be the second biggest production source after total coal production, providing about 30% of the energy production. Fig. 1 illustrates energy and exergy flows in a macro system for Turkey’s whole and the TRCS. In 2000, of Turkey’s total end-use energy, 39% was used by the industrial sector, followed by the residential–commercial sector at 33%, the transportation sector at 20%, the

Table 1 Values for population, number of dwelling units and energy/exergy consumptions from 2000 to 2020 Year

Population

Number of dwelling units

Total energy consumption (PJ)

Total exergy consumption (PJ)

Residential energy consumption (PJ)

Residential exergy consumption (PJ)

2000 2005 2010 2015 2020

67,803,927 72,427,248 76,840,418 81,606,043 85,554,317

16,237,852 17,855,008 19,121,333 20,807,414 22,192,965

3527.2 5616.67 7558.66 10,175.65 12,898.51

3469.62 5461.51 7401.66 9978.37 12,636.99

814.1 1113.92 1302.82 2506.25 3138.62

775.65 1044.08 1214.27 2001.69 2990.75

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agricultural sector at 4.8%, and the non-energy (out of energy) use at 3.2% [40,46]. However, in 2020, they are estimated to be 58% by the industrial sector, followed by the residential–commercial sector at 24%, the

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transportation sector at 15%, the agricultural sector at 3%, and the non-energy (out of energy) use at 1% [37,46]. 3.1. Energy and exergy utilization in the Turkish residential–commercial sector

Table 2 Energy and exergy input values during 2000 and 2020 a

2000

Energy carrier toe/q

(PJ) Hard coal Lignite Asphaltite Petroleum Natural gas Wood Biomass Hydro Geothermal Solar Wind Coke Petrocoke Nuclear

Total

0.61 1.03 0.21 1.04 1.03 0.97 1.05 0.99 0.91 0.92 0.30 1.05 0.23 1.05 0.09 1.00 0.86 0.29 0.86 0.93 0.09 1.00 0.70 1.05 0.77 1.04 0.26 1.00

Enegy Exergy Energy Exergy Energy Exergy Energy Exergy Energy Exergy Energy Exergy Energy Exergy Energy Exergy Energy Exergy Energy Exergy Energy Exergy Energy Exergy Energy Exergy Energy Exergy

2020 (%)

388.7 11.02 400.4 11.54 534.1 15.15 555.4 16.01 0.4 0.01 0.4 0.01 1477.4 41.89 1462.7 42.15 571.2 16.20 525.5 15.15 212.4 6.02 223.02 6.43 57.5 1.63 60.3 1.74 138.7 3.93 138.7 4.00 64.7 1.84 18.8 0.54 9.4 0.27 8.7 0.25 0.8 0.02 0.8 0.02 21.1 0.59 22.1 0.64 50.8 1.44 52.8 1.51 N/A N/A N/A N/A

(PJ)

(%)

3749.10 3861.60 1620.02 1684.82 1.80 1.85 2824.94 2796.69 3147.61 2895.80 128.54 134.96 35.53 37.31 350.33 350.33 225.47 65.39 275 255.75 28.10 28.10 N/A N/A N/A N/A 688.00 688.00

29.07 30.56 12.56 13.33 0.01 0.01 21.90 22.13 24.40 22.92 1.00 1.07 0.28 0.30 2.72 2.77 1.75 0.52 0.77 0.73 0.22 0.22 N/A N/A N/A N/A 5.33 5.44

Energy 3527.20 100.00 12,898.51 100.00 Exergy 3469.62 100.00 12,636.99 100.00

a

The upper values are conversion factor to tons of oil equivalent (toe), while the lower values are quality factor.

The TRCS includes space heating, water heating, cooking and electrical appliances for energy consumption. In the following subsections, the utilization of energy and exergy in the TRCS in the years of 2000 and 2020 is analyzed. The figures for energy and exergy consumptions were determined for 2000–2003, while they are projected from 2004 to 2020, as shown in Fig. 2. In 2000, of Turkey’s end use energy, 33% was used by the residential sector, while the share of this sector in this breakdown is expected to continue to decrease at approximately 9–12% per year and to reach 20% in 2020. Table 3 illustrates the use of energy and exergy as well as the shares of the resources in this sector for the years of 2000 and 2020, respectively. Share of the energy utilization in the residential–commercial modes is as follows: space heating with 45% and 42%, water heating with 27% and 30%, cooking with 9% and 12% and electrical appliances with 18% and 17% in the years studied, respectively. These values are determined for 2000 and are projected for 2020 by using figures obtained from Refs. [37,41]. Table 3 shows energy and exergy utilization values for the years studied in the TRCS. The highest contributions came from renewable resources (includes wood) with 41.50% and 20.01%, fuel with 38.70% and 61.91%, and electric with 19.80% and 18.08% in 2000 and 2020, respectively. In 2000, the highest contributions came from wood with 212.40 PJ, while the share of this resource in this breakdown is expected to continue to decrease at approximately 3–5% per year and to reach 128.54 PJ in 2020. However, natural gas usage has continuously increased in the TRCS for space heating, water heating and cooking purposes in several cities. Product

Waste

Industrial

Waste Space heating

Electricity

Utility

Residentialcommercial

Product Product

Resources

Transportation

Cooking

Waste Product

Agricultural

Product Waste

Waste

Waste Product

Water heating

Waste

Electrical appliances

Product Waste

Fig. 1. An illustrative presentation of the energy flows in a macro system and the Turkish residential–commercial sector.

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646 13500 12500 11500

Energy values (PJ)

10500

2

9500 8500 2

7500 y

6500

x 24 .85 =4

+

+ 7x 5.9 37

R 23 28

65 .99 =0

5500 4500 3500

2 .9946 8R =0 + 863.3 2 - 15.505 x x 57 y = 6.89

2500 1500 500 2000

2002

2004

2006

2008

2010

2012

2014

2016

2018

2020

Years Fig. 2. Energy demand for Turkey’s total (n) and the Turkish residential–commercial sector (&) over the period from 2000 to 2020.

Table 3 Utilization of energy and exergy in the Turkish residential–commercial sector in 2000 and 2020 Energy carrier

Energy/Exergy

2000 Input (PJ)

2020 Sector (%)

Turkey (%)

Input (PJ)

Sector (%)

Turkey (%)

Hard coal

Energy Exergy

18.21 18.75

2.24 2.42

0.52 0.54

896.57 923.47

28.57 30.88

6.95 7.31

Lignite

Energy Exergy

43.24 44.97

5.31 5.80

1.23 1.30

274.00 284.96

8.73 9.53

2.12 2.25

Asphaltite

Energy Exergy

0.14 0.15

0.02 0.02

0.004 0.004

1.91 1.85

0.06 0.06

0.01 0.01

Petroleum

Energy Exergy

148.22 146.73

18.21 18.92

4.20 4.23

315.60 312.44

10.06 10.45

2.45 2.47

Natural gas

Energy Exergy

103.73 95.43

12.74 12.30

2.94 2.75

453.68 417.39

14.45 13.96

3.52 3.30

Wood

Energy Exergy

212.40 223.02

26.09 28.75

6.02 6.43

128.54 134.96

4.10 4.51

1.00 1.07

Biomass

Enegy Exergy

57.50 60.38

7.06 7.78

1.63 1.74

35.53 37.31

1.13 1.25

0.28 0.30

Electric

Energy Exergy

161.27 161.27

19.81 20.79

4.57 4.65

565.77 565.77

18.03 18.92

4.39 4.48

Geothermal

Energy Exergy

62.08 18.00

7.63 2.32

1.76 0.52

190.50 55.25

6.07 1.85

1.48 0.44

Solar

Energy Exergy

5.93 5.52

0.73 0.71

0.17 0.16

275.00 255.75

8.76 8.55

2.13 2.02

Coke

Energy Exergy

1.37 1.44

0.17 0.19

0.04 0.04

1.52 1.60

0.05 0.05

0.01 0.01

Total

Energy Exergy

814.10 775.65

100.00 100.00

23.08 22.36

3138.62 2990.75

100.00 100.00

24.33 23.66

Natural gas constituted 103.73 PJ of used energy in this sector in 2000 and is projected to account for 453.68 PJ of that in 2020. In addition, utilization of renewable

energy is spread in the TRCS, especially from sunlight for water heating, from geothermal for water heating and space heating and from biowaste for general usage.

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3.2. Estimation of component and overall efficiencies for fuel utilization

as follows: district heating at 2.50%, central heating at 5.30%, individual heating at 4.30%, stove at 84.10% and others 3.80%. Considering the figures listed in Table 5 for 2000, the projections were made for 2020, as presented in Table 6. It is expected that stoves will be widely used for heating purposes even in 2020 with 73.11% according to Ref. [37]. The fuel consumption estimation methods in the literature are based on complete heating of space, whereas in stove heating, space is partially heated. Central heating methods can be adapted to other countries; stove heating must be analyzed based on national data. In a study performed by Aycik et al. [48], thermal efficiencies of coal- and wood-fired stoves used in Turkey were found to be on average 45% and 35%, respectively. Besides this, according to the Turkish Standard (TS) 4900, the thermal efficiencies of coalfired stoves should be greater than 70% [49]. It is assumed that average efficiencies of stoves in the country will increase 2% in every 5 years up to 2020. The second law efficiency of space heating was calculated from the equation

Various fuels given in Table 3 are used for the purposes of water heating, space heating and cooking activities in this sector. Energy utilization values for the TRCS are also indicated in Table 4. Space heating requires the largest fraction of fuel with about 43% and 50%, while water heating and cooking are responsible for 37% and 32%, and 20% and 18% of the total fuel inputs in these years, respectively. 3.2.1. Space heating Based on the values obtained from Turkey’s population census, the fuel preferences of dwelling units for space heating were determined for each province, while energy consumptions in residences were predicted according to geographical regions and selected provinces in 1998 in Turkey [47]. The distribution of heating systems according to their utilization ratios for 1998 is Table 4 Energy utilization values of the Turkish residential–commercial sector by components in 2000 and 2020 Component

Lighting (Incandescent) (Fluorescent) Refrigeration Water heating Cooking Space heating Washing machine Vacuum cleaner Air conditioning Television Iron Miscellaneous

a



Renewablesa (%)

Electrical (%)

Fuels (%)

2000

2020

2000 2020 2000

35 (70) (30) 40 4 3 2 2 1 2 6 1 4

38 (30) (70) 35 3 4 2 2 2 4 7 1 2

100

100


2 ¼

2020

37 20 43

32 18 50

30 2 68

54

100

100

100

100

647


1 qfuel



 1

   T0 T2 ln : T2  T0 T0

(16)

In all, 43–52% of all direct fuel use was for space heating, which is done entirely by home heaters having the same first law efficiencies of home stoves. It is assumed that, a fuel with a quality factor of about 0.99 is fired, the supply temperature for the space heating equipment is 50 1C and the ambient temperature is 20 1C [15,34,35]. Using Eq. (16), the numerical values and the first law efficiencies assumed, we found e2 for energy carriers for space heating, as shown in Table 7. Overall first (e1sh,f) and second law (e2sh,f) efficiencies of space heating were calculated as follows:

46


1;o ¼ ½ða1
1c Þ þ ða2
2c Þ þ ða3
3c Þ þ    þ ða9
9c Þ=100 (17a)

Renewables include biomass, wood, geothermal and solar.

Table 5 Distribution of residences according to fuel types and components of fuel uses in 2000 (%) Space heating

Coal

Fuel-oil

Natural gas

Wood

Geothermal

District heating Central heating Individual heating Stove Other Total

60 39 — 72.67

20 25 6 0.8

18 36 94 3.50

— — — 19

2

Cooking Water heating

Electric

Ratio of residences

3.85

Gas- LPG combined heater

Solar

Natural gas

Stove

Electric

2.5 5.3 4.3 84.1 3.8 100.0 Other

91.7 42.6

— 10.10

7.50 —

0.3 33.6

0.3 7.80

— 5.90

100.0 100.0

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Table 6 Projected values of residences according to fuel types and components of fuel uses in 2020 (%) Space heating

Coal

Fuel-oil

Natural gas

Wood

Geothermal

District heating Central heating Individual heating Stove Other Total

37 37

22.9 25 6 0.8

37.1 38 94 2.50

— — — 19.17

3

Gas-LPG

Solar

Natural gas

Stove

Electric

Combined heater

100.0 Other

84.14 40.35

— 29.35

15.26 —

0.3 18.1

0.3 6.80

3.14

— 2.26

Cooking Water heating

74.7

Electric

Ratio of residences 5.16 12.15 9.58 73.11

2.83

100.0 100.0

Table 7 Energy and exergy efficiency values for space heating, water heating and cooking according to fuel types (%) Fuels

Space heating 2000

Water heating 2020

2000

2020

e1

e2

e1

e2

e1

Coal (stove) Coal Fuel-oil Natural gas LPG Electricity Wood Geothermal Solar Dried-dung

45 50 65 84 90 98 55 54

3.2 3.6 4.9 6.3 7.4 7.3 2.5 53

55 60 65 84 90 98 50 54

4.3 4.6 5.8 7.2 7.4 7.6 3.4 5.3

45

3.2

80 80 90 30 54 30

9.6 9.7 10.8 3.4 5.3 3.9

35

2.5

35

2.5

Overall (e1sh,of; e2sh,of)

50.32

2.65

61.08

4.95

Overall fuels (e1,ofrcs; e2,ofrcs)

51.70

4.66

61.02

6.96


2;o ¼ ½ða1
1c Þ þ ða2
2c Þ þ ða3
3c Þ þ    þ ða9
9c Þ=100 (17b) Substituting the relevant numerical values into Eqs. (17a) and (17b), we obtained esh,f=50.32% and 61.08%, and e2sh,f=2.65% and 6.59% in 2000 and 2020 for space heating, respectively. 3.2.2. Water heating In 2000, 37% of all direct fuel use was for water heating. First law efficiencies of direct fuel use for water heating are assumed to be 27–80% [34], as shown in Table 7. The second law efficiency of water heating was calculated from Eq. (16). It is assumed that hot water and ambient temperatures are 60 and 20 1C, respectively, while quality factor ðqfuel Þ is 0.99 for direct fuel uses. Substituting the relevant numerical values into Eq. (16), we obtained the figures ranging from 3.10% to 10.80% for all energy carriers, as indicated in Table 7.

e2

60.43

Cooking

3.95

2000

2020

e1

e2

e1

e2

e1

e2

60 — 65 80 80 90 40 54 50 27

4.3 — 4.9 9.6 9.8 10.8 4.2 6.2 6.2 3.1

— —

— —

50 50 80 22

10.7 10.8 17.2 45

60 — 65 65 55 80 22

4.3 — 49 11.5 11.8 17.2 4.5

20

4.1

— 20

— 4.1

56.6

11.7

63.58

7.56

40.32

10.30

Using Eqs. (17a) and (17b) and the numerical values assumed, we found e1wh,f=60.43% and 63.58%, and e2wh,f=3.95% and 7.56% in 2000 and 2020 for water heating, respectively. 3.2.3. Cooking In cooking activities, various fuels such as natural gas, city gas, LPG, etc. are used. Overall, 20–18% of all direct fuel use was for cooking. The first law efficiencies assumed are listed in Table 7, while the cooking and ambient temperatures are assumed to be 120 and 20 1C, respectively [34]. The second law efficiencies were calculated by the following equation:    T0
2 ¼
1 1  : (18) T2 Using Eq. (18), these assumptions yield second law efficiencies of fuel use ranging from 4.1% to 17.2% for the years studied, as indicated in Table 7.

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Overall first (e1c,f) and second law (e2c,f) efficiencies were calculated from Eqs. (17a) and (17b) in a similar way and were found to be 40.32% and 56.60%, and 10.30% and 11.70% in 2000 and 2020 for cooking, respectively. Overall sectoral first and second law efficiencies for the fuel utilization were calculated by the following equations, respectively.
1;of ¼ ½ðf sh
1sh;f Þ þ ðf wh
1wh;f Þ þ ðf c
1c;f Þ=100

(19a)


2;of ¼ ½ðf sh
2sh;f Þ þ ðf wh
2wh;f Þ þ ðf c
2c;f Þ=100:

(19b)

Substituting the relevant numerical values into Eqs. (19a) and (19b), we obtained e1o,f=51.70% and 61.02%, and e2o,f=4.66% and 6.96% in 2000 and 2020 for the fuel utilization in the TRCS, respectively. 3.3. Estimation of overall efficiency and effectiveness values for renewable energy utilization The overall efficiency and effectiveness values for renewables uses in the TRCS were estimated as follows: 3.3.1. Space heating The contribution of geothermal energy to the TRCS was 62.08 PJ for space heating in 2000. However, it is expected that geothermal usage will continue to increase to 190.50 PJ in 2020 in direct use of geothermal energy for heating [42]. Substituting the relevant numerical values into Eqs. (17a) and (17b), we obtained e1shr=54, 58% and e2shr=5.3, 6.2% in 2000 and 2020 for space heating, respectively. 3.3.2. Water heating In 2000, 32% of all renewable energy use was for water heating. Ratio of residences with solar collectors for water heating in 2000 and 2020 was at 10.1% and 29.35%, respectively. Although Turkey has a huge solar energy potential, of this potential is used only small part for water heating. First law efficiencies of solar collector use for water heating are assumed to be 30–50% [36,37]. The second law efficiency of water heating was calculated from Eq. (16). It is assumed that hot water and ambient temperatures are 60 and 20 1C, respectively, while qfuel is 0.99 for direct fuel uses. Substituting the relevant numerical values into Eq. (16), we obtained e2 values ranging from 3.10% to 6.2% for all renewable energy and e2=3.9–6.2% for solar collectors, 3.4–4.2% for wood and 2.5–3.1% for animal waste from 2000 to 2020, respectively. Using Eqs. (17a) and (17b) and the numerical values assumed, we found first and second law efficiencies e1whr=30.07% and 46.62%, and e2whr=3.69% and 5.49% in the years studied for water heating, respectively.

649

3.3.3. Cooking In cooking activities, share of wood was 0.3% in the country in 2000, but no usage renewable for cooking in 2020. Overall first (e1c,) and second law (e2c,) efficiencies were calculated from Eqs. (17a) and (17b) in a similar way and were found to be 22% and 4.5% for cooking in 2000, respectively. Overall sectoral first and second law efficiencies for renewable use were calculated by the following equations:
1;ofrcs ¼ ½ðrsh
1sh;or Þ þ ðrwh
1wh;or Þ þ ðrc
1c;or Þ=ðrsh þ rwh þ rc Þ

ð20aÞ


2;ofrcs ¼ ½ðrsh
2sh;ro Þ þ ðrwh
2wh;rof Þ þ ðrc
2c;ro Þ=ðrsh þ rwh þ rc Þ

ð20bÞ

where r denotes the renewable use by the residential–commercial sector in energy terms [42]. Substituting the relevant numerical values into Eqs. (20a) and (20b), we obtained e1,orrcs=46.18% and 51.85%, and e2,orfrcs=4.8% and 5.82% in 2000 and 2020, for renewable energy use in this sector, respectively. 3.4. Estimation of overall efficiency and effectiveness values for electric utilization As living standards rise, use of electrical appliances is increasing fast and boosting electricity demand. Increasing use of air-conditioning, especially in the Mediterranean region, has shifted the peak hours of electricity demand to noon in the summer. Electrical energy is used for various purposes such as lighting, refrigeration, television, washing machine, etc. in this sector. Energy utilization values for the TRCS are indicated in Table 4, while the saturation values of electrical appliances are given in Table 8 [49]. Refrigeration requires the largest fraction of electricity with 40–35% in the years studied, followed by lighting with 35–38%. The overall efficiency and effectiveness values for electric utilization were estimated as follows [15,36,37]: 3.4.1. Lighting Approximately 35–38% of all electrical use was for lighting [50]. Electrical energy consumption value for lighting was 138 kWh per dwelling unit annually in 1990 [47]. Annual electricity consumption of dwelling unit for lighting is assumed to change linearly from 138 kWh, reaching 180 kWh in 2001, 230 kWh in 2010 and 260 kWh in 2020 [37,51]. Lighting is assumed to be 80% incandescent and 20% fluorescent with first and second law efficiencies of about 5% and 4.5%, and 20% and 18.5%, in 2000, respectively [38,41]. Utilization ratio of fluorescent in

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650

Table 8 Saturation values of electrical appliances in 1998, 2000 and 2020 (%) Type of appliances

1998a

2000

2020

Lighting (Incandescent) (Fluorescent) Refrigeration Television Washing machine Dishes machine Vacuum cleaner Air conditioning Clothes drying Electrical furnace Hair drying machine Computer

100 (80) (20) 97.38 96.59 78.97 14.49 77.21 1.26 92.54 74.57 61.62 3.6

100 (70) (30) 99 99 86.20 30.30 89.19 1.45 96.60 90.00 82.40 3.9

100 30 70 99 99 95 65.45 92.40 9.25 98.75 95.00 89.00 24

a The values for 1998 are obtained from Ref. [49], while those for 2000 and 2020 are estimated.

Table 9 Energy and exergy efficiency values of electrical appliances (%) Component

2000

2020

e1

e2

e1

e2

Lighting (Incandescent) (Fluorescent) Refrigeration Water heating Cooking Space heating Washing machine Vacuum cleaner Air conditioning Television Iron Miscellaneous

9.5 (5) (20) 100 90 80 98 80 70 200 80 98 70

8.7 (4.5) (18.5) 10.6 10.8 17.2 7.3 80 70 14 80 30 65

15.5 (5) (20) 150 90 80 98 90 80 200 80 98 90

14.3 4.5 (18.5) 15.7 10.8 17.2 7.3 90 80 14 80 30 70

Overall efficiencies

80.98

22.17

86.03

23.35

lighting is expected to increase from 20% in 2000 to 70% in 2020, as given in Table 9. Combining the relevant first and second law efficiencies for lighting, we calculated e1=9.5–15.5% and e2=8.70–14.3% for the years considered, as indicated in Table 9. 3.4.2. Refrigeration Refrigerators are consumed huge share of electricity. Of all electrical use, 40–35% was for refrigeration [48,51]. New technology for refrigerators electricity consumption is decreased. Electricity consumption is projected to decrease by using new technologies for refrigerators. Average annual consumption was calculated to be 346 kWh in 1990, 328 kWh in 1995 and 300 kWh in 2001 and 2005, and 275 kWh in 2020 [37].

The second law efficiency of refrigeration was calculated from    T0 1 : (21)
2 ¼
1 T3 It is assumed that the temperatures inside freezers and refrigerators are approximately 8 1C, the coefficient of performance (COP) is 1.0 and the room temperature near the refrigerator coil is 20 1C. Using Eq. (21), these assumptions yield e2=10.60% in 2000, while second law efficiencies are given in Table 9 for 2020. 3.4.3. Water heating In 2000, 4% of all electrical use was water heating. First law efficiencies of electrical use for water heating are assumed to be 90% [36]. It is assumed that hot water and ambient temperatures are 60 and 20 1C, while quality factor ðqfuel Þ is 1.0 for electrical use. The second law efficiency of water heating was calculated from Eq. (16) and was found to be 10.8%, as given in Table 9. 3.4.4. Cooking In all, 3–4% of all direct electric use was for cooking. It is assumed that first law efficiency of electrical use is 80%, and the cooking and ambient temperatures are 120 and 20 1C, respectively [34]. Using Eq. (18), these assumptions yield e2=17.2% for cooking. 3.4.5. Space heating In all, 2% of all direct electrical use was for space heating. It is assumed that, first law efficiency is 98%, the supply temperature for the space heating equipment is 50 1C and the ambient temperature is 20 1C [15,36]. Using Eq. (18), the numerical values and the first law efficiencies assumed, we found e2=7.3% for space heating. 3.4.6. Air conditioning Assuming that the COP value of the electric air conditioning unit is 2, this unit extracts heat from air at 14 1C and the outside temperature is 35 1C and using Eq. (21) in a similar manner, we found e2=14% in the years studied. 3.4.7. Television In all, 6–7% of all electrical use was for television and computer. Annual electricity consumption of television has increased compared to previous years due to an increase in the number of TV channels, a longer daily broadcast period and utilization of colored TVs. First and second law efficiencies are assumed to be 80%. 3.4.8. Others Electricity consumption values of other electrical appliances, for instance washing machine, dish washer, iron, computer and vacuum cleaner were selected

ARTICLE IN PRESS Z. Utlu, A. Hepbasli / Building and Environment 40 (2005) 641–655

estimated as given in Table 4, while the first and second law efficiencies of these appliances are listed in Table 9. Substituting the relevant numerical values into Eqs. (17a)–(17b), we found e1=66.16% and 86.03%, and e2=18.66% and 23.35% for electrical use in 2000 and 2020, respectively. Overall first and second law efficiencies (e1,orc and e2,orc) for the entire residential–commercial sector were calculated by aggregating both purchased electrical energy and direct fuel use as follows:

1e erc þ
1of f erc þ
1r rrc

1;orc ¼ (22a) erc þ f erc þ rrc
2;orc



2e erc þ
2of f exrc þ
2r rexrc : ¼ ðerc þ f exrc þ rexrc Þ

651

10.07% in 2000 and 2020, respectively. It also should be noted that energy and exergy efficiencies for the TRCS sector are almost similar, as also denoted by Dincer et al. [25]. Furthermore, a variation of the overall mean energy and exergy efficiencies for the TRCS between from 2000 to 2020 is shown in Fig. 3. As may be seen in this figure, there is major differently energy and exergy efficiencies, consciously increasing up to 2020. 3.5. Development of energy and exergy efficiencies in the Turkish residential–commercial sector As can be seen in Fig. 3, where a comparison of energy and exergy efficiency values for the TRCS is also illustrated, the energy efficiencies in the years studied range from 57.05% to 65.53%. Besides these, the exergy efficiencies vary from 8.02% to 10.07%. This sector shows considerably important and comparable losses of energy and exergy. In terms of exergy loses, this sector

(22b)

Using the numerical values given in Table 9, the weighted mean overall energy and exergy efficiencies for the entire residential–commercial sector were found to be e1orc=57.05% and 65.53%, and e2orc=8.02% and Energy

Exergy

70 65 60 55

Overall efficiency (%)

50 45 40 35 30 25 20 15 10 5 0 2000

2002

2004

2006

2008

2010

2012

2014

2016

2018

2020

Years

Fig. 3. Energy and exergy efficiency values for the Turkish residential–commercial sector over the period from 2000 to 2020.

Table 10 Energy and exergy efficiency values of the Turkish residential–commercial sector in 2000 and 2020 (%) 2000

2020

e1

e2

e1

e2

Space heating (e1sh,of; e2sh,of)a Water heating (e1wh,of; e2wh,of)a Cooking (e1c,of; e2c,of)a Overall sector for fuel use (e1,ofrcs; e2,ofrcs)a

50.32 60.43 40.32 51.70

2.65 3.95 10.30 4.66

61.08 63.58 56.60 61.02

4.95 7.56 11.75 6.96

Overall sector for electrical energy use (e1,oercs; e2,oercs)

80.98

22.17

86.03

23.35

Entire sector (e1,orcs; e2,orcs)

57.05

8.02

65.53

10.07

a

Fuel and renewables are included.

652

Investigators

Year analyzed/ published

Population

1991/1994

57,024,515

Rosen and Dincer [15]

1993/1997

58,808,625

Ileri and Gurer [36]

1995/1998

59,706,545

Utlu and Hepbasli [41]

1999

66,022,636

2000

67,803,927

Utlu and Hepbasli [38]

2001/2003

68,820,985

Present study

2020

85,554,317

a

Total energy (exergy) outputs

Residential energy (exergy) inputs

Residential energy (exergy) outputs

Efficiencies
1 =ð
2 Þ

PJ

PJ

PJ

PJ

GJ/cap

Total (%)

TRCS (%)

2275 (2279) 1645.2 (680.60) 2695.20 (2697.30) 3391.66 (3380.34) 3527.33 (3469.62) 3194.90 (3137.77)

GJ/capita

GJ/capita

GJ/cap

39.90 (39.97) 27.98 (11.57) 45.14 (45.17) 51.37 (51.20) 53.42 (52.55) 51.37 (51.20)

1029.50 (539.50) 680.60 (445.20) 938.90 (352.30) 1153.46 (499.61) 1250.03 (525.77) 1438.34 (781.44)

18.05 (9.46) 11.57 (7.57) 15.73 (5.90) 17.47 (7.55) 18.93 (7.96) 20.90 (11.35)

752.86 (761.24) 83.8 (83.9) 830.9 841.1 748.57 (752.88) 814.09 (775.66) 817.45 (776.77)

13.20 (13.35) 1.42 (1.43) 13.92 14.09 11.34 (11.40) 12.01 (11.44) 11.88 (11.29)

414.07 (82.97) 57.20 10.10 460.70 (52.20) 432.37 (61.13) 464.44 (62.21) 455.73 (69.75)

7.26 (1.45) 0.97 (0.17) 7.72 (0.87) 6.55 (0.93) 6.85 (0.92) 6.62 (1.01)

45.30 (23.70) 41.40 (27.10) 34.90a (13.10) 43.24 (24.04) 44.91 (24.78) 45.02 (24.96)

55.00 (10.90) 68.25 (12.05) 55.49 (6.21) 57.76 (8.12) 57.05 (8.02) 55.75 (8.98)

12,898.51 150.76 (12,636.99) (147.78)

7098.18 (3848.69)

82.97 (44.99)

3138.62 (2990.75)

36.69 (34.96)

2056.74 (301.17)

24.04 (3.52)

55.15 (30.44)

65.53 (10.07)

Excluding utility sector use. These values are obtained to be 43.61 (21.83)% with a utility sector use of 236.6 PJ [36]. Exergy values are given in parentheses.

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Unal [34]

Total energy (exergy) inputs

Z. Utlu, A. Hepbasli / Building and Environment 40 (2005) 641–655

Table 11 Comparison of total energy and exergy inputs/outputs as well as energy and exergy utilization efficiencies of the Turkish residential–commercial sector [15,34,36,38,41]

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ranks rather differently, accounting for about 89–91% of all exergy loses. This study indicated that exergy utilization in Turkey was even worse than energy utilization. In other words, Turkey represents a big potential for increasing the exergy efficiency. It is clear that a conscious and planned effort is needed to improve exergy utilization in Turkey. Considering the existence of energy-efficient technologies in the world, the major problem is delivering these technologies to consumers or, in other words, using effective energy-efficiency delivery mechanisms, as reported in detail elsewhere [52,53]. These results Exergy output

Exergy input 3500

3000

Exergy values (PJ)

2500

2000

1500

1000

500

0 2000

2002

2004

2006

2008

2010

2012

2014

2016

2018

2020

Years

Fig. 4. Exergy input and output values of the Turkish residential–commercial sector over the period from 2000 to 2020.

653

indicate the need of saving in the use of energy and to improve habits of energy use in this sector and its sub sectors. The space heating, constitutes the biggest energy loss, followed by the water heating and cooking activities in the TRCS. From the evaluation of the results given in Table 10, it may be concluded that the TRCS has about equal and fairly high energy efficiencies, while it indicates a very poor performance in terms of its exergy efficiency values. 3.6. Comparison of turkey’s energy and exergy efficiency values Table 11 [15,34,36,38,41] illustrates a comparison of the total energy and exergy inputs/outputs, of which values between 2000 and 2020 are shown in Fig. 4, as well as energy and exergy efficiency values for the TRCS. Evaluating the results of this table indicates that Turkey’s overall energy and exergy efficiencies between 1991 and 2020 range from 41.40% to 55.15%, and from 21.83% to 30.44%, with average values of 45.60% and 25.32% over the period considered, respectively. Besides this, the values of the energy efficiency for the TRCS are found to be in the range of 55% and 68.25%, while those of the exergy efficiency vary from 6.21% to 12.05%. Table 12 shows a comparison of exergy efficiency values of different countries for the residential–commercial sector [16,26,38,41]. Although the sectoral coverage differs slightly from each other, it is useful to illustrate the situation on how exergy efficiencies vary in various societies. It also should be noted that the variation is mainly due to different assumptions on

Table 12 Comparison of different countries in terms of exergy efficiencies in the residential–commercial sector [16,26,38,41] Country

Year

Methodology used

Exergy efficiency (%)

References

USA Sweden Finlanda Japan Canadaa Brazila Italy OECDa Worlda Norway Saudi Arabiab Saudi Arabiab Turkey Turkey Turkey

1970 1980 1985 1985 1986 1987 1990 1990 1990 1995 2000 2001 1999 2000 2001

Reistad’s approach Wall’s approach Reistad’s approach Wall’s approach Reistad’s approach Reistad’s approach Wall’s approach Reistad’s approach Reistad’s approach Reistad’s approach Reistad’s approach Reistad’s approach Reistad’s approach Reistad’s approach Reistad’s approach

14.00 10.00 8.00 3.00 15.00 12.00 2.00 7.00 5.00 11.00 8.68 8.73 8.02 8.02 8.98

[16] [16] [16] [16] [16] [16] [16] [16] [16] [16] [26] [26] [41] [41] [38]

Turkeyc

2020

Reistad’s approach

10.07

Present study

a

Losses associated with non-energy use are not included. Exergy efficiency values have been determined for a 12 year period of 1990–2001, while they are given here only for the years of 2000 and 2001. c Exergy efficiency values have been estimated for a 20 year period of 2000–2020, while they are included here only for the year of 2020. b

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efficiencies by the investigators, as also denoted by Ertesvag [16].

4. Conclusions In this study, using a method proposed by Rosen and Dincer [15], who applied Reistad’s approach [17] with several minor differences, energy and exergy efficiencies of the TRCS were analyzed based on the actual and projected data for 2000 and 2020, respectively. These efficiency values obtained for Turkey were also compared to those reported by other investigators. The main conclusions derived from the present study may be summarized as follows: (a) Based on the estimations in energy and exergy consumptions, annual energy consumption in the TRCS is expected to increase by 6.5% from 2000 to 2020. (b) The average overall energy and exergy efficiencies for the residential–commercial sector of Turkey are found to be 44.91% and 24.78% in 2000, while they are projected to be 55.15% and 30.44% in 2020, respectively. (c) The energy efficiency value for the TRCS is obtained to be 55.60% in 2000, and is expected to be 65.53% in 2020. The exergy efficiency value for that is expected to increase from 8.02% in 2000 to 10.07% for 2020. The exergy efficiency values appear to be much less than their corresponding energy efficiency values due the large amount of losses taking place in the TRCS. (d) It may be concluded that the analyses reported here will provide the investigators with a better, quantitative grasp of the inefficiencies and their relative magnitudes in evaluating the energy utilization performance of countries.

Acknowledgements The authors are grateful for the present work by the Ministry of Energy and Natural Resources of Turkey and World Energy Council Turkish National Committee. The valuable comments of the reviewers are also gratefully acknowledged.

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