Thermodynamic and environmental analyses of biomass, solar and electrical energy options based building heating applications

Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

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Renewable and Sustainable Energy Reviews journal homepage: www.elsevier.com/locate/rser

Thermodynamic and environmental analyses of biomass, solar and electrical energy options based building heating applications Hakan Caliskan 1 Department of Mechanical Engineering, Faculty of Engineering, Usak University, 64200 Usak, Turkey

art ic l e i nf o

a b s t r a c t

Article history: Received 24 February 2014 Received in revised form 29 October 2014 Accepted 25 November 2014

In this study, the biomass, solar, and electrical energy options based building heating are investigated and compared along with energy, exergy, sustainability, environmental, exergoenvironmental, enviroeconomic and exergoenviroeconomic analyses. All of the analyses are presented gradually to show the complete energy and exergy based advanced analyses. Eight different reference temperatures are considered which are varying from 4 1C to 7.5 1C with a temperature interval of 0.5 1C. The most efficient and sustainable energy option of the building is found to be solar energy, while biomass energy is the second one. Furthermore, according to environmental analysis, maximum 0.1599 kg-CO2 is released in a day for the solar energy option, while this value is 0.6082 kg-CO2 for the biomass energy, and 29.614 kgCO2 for the natural gas fired electrical energy 4 1C reference temperature. In addition, among the energy options, solar and biomass energies have the best exergoenvironmental results in which exergetic results are taken into account. Finally, the maximum released CO2 prices in a day are determined at 4 1C reference temperature to be 0.0088 $, 0.0023 $, and 0.4294 $, while the corresponding exergoenviroeconomic results are found as 0.0040 $, 0.000933 $, and 0.4294 $ for the biomass, solar, and electrical energy options, respectively. & 2014 Elsevier Ltd. All rights reserved.

Keywords: Energy Enviroeconomic Environmental Exergy Exergoenviroeconomic Exergoenvironmental Heating

Contents 1. 2. 3.

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . System description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1. Energy analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2. Exergy analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3. Sustainability analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4. Environmental analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5. Exergoenvironmental analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6. Enviroeconomic analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7. Exergoenviroeconomic analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. Results and discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1016 1017 1019 1019 1020 1021 1021 1022 1022 1022 1022 1031 1033

1. Introduction

E-mail addresses: [email protected], [email protected] Tel.: þ90 276 221 21 21x2756; fax: þ 90 276 221 21 37.

1

http://dx.doi.org/10.1016/j.rser.2014.11.094 1364-0321/& 2014 Elsevier Ltd. All rights reserved.

Energy consumption and demand of the world have been rising year after year. According to U.S. Energy Information Administration, energy consumption of the world increases by 53% from 2008 to 2035. Energy demand also grows 0.6% and 2.3% per year for

H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

Organization for Economic Co-operation and Development (OECD) and non-OECD countries, respectively [1]. In the last decades, most of the energy is produced by non-renewable traditional energy sources, such as coal, natural gas, oil, etc., that crate a risk for environment and human life [2]. On the other hand, 10% of energy consumption is from environmentally friendly renewable energy sources like solar, wind, biomass, etc. Furthermore, 19% of world electricity generation is from renewable energy [3]. Most of total primary energy is utilized in buildings. It may be reduced by using renewable sources and applying energy/exergy efficiency strategies [4]. 40% of total energy use occurs in buildings which also causes 36% of European Union’s total CO2 emissions. The utilization of renewable energy sources in the buildings causes reduction in energy imports and greenhouse gases [5]. The renewable energy capacity increases globally. Most of the countries (more than 85) adapt their policies basing on renewable energy sources (such as biomass, solar, etc.) [6]. One of the most important renewable energy sources is biomass which includes some primary materials and can be used directly or be converted into secondary fuels. So, the biomass based heating systems (e.g. biomass boiler) are considered as efficient energy systems [7]. The biomass for energy can be classified as residual and purpose grown biomasses. The residual biomass is a product of the industry (e.g. forest timber and waste wood). The purpose grown biomass is especially produced crop that only used for energy production [8,9]. The benefits of biomass are discovered throughout the 20th century. Some advantages of biomass can be thought such as additional economic, environmental and social benefits. Biomass energy sources decrease the level of atmospheric hazardous gases (e.g. SO2). Also, biomass causes no net release of CO2 when sustainable purpose grown biomass is supplied [10,11]. Alongside of biomass, solar energy counts for 13% of the energy consumption in buildings [12]. The utilization of solar thermal energy has grown in recent years. There are solar collectors with the area of 19 million m2 in Europe. Solar thermal energy is generally used for low heat requirements such as space (floor) heating in buildings. Solar thermal energy can supply heat to the buildings for summer, late spring and early autumn seasons. It is also useful as a product for energy suppliers. Solar collectors can be installed on factory and residential roofs to generate heat for consumers [13]. Energy analysis is generally not fully sufficient to evaluate systems. So, an analysis based on both of first and second laws of thermodynamics may be necessary. This analysis is named as exergy or availability analysis. Exergy is a potential or quality of energy and it is possible to make sustainable quality assessment of energy. This analysis is useful tool to compare different types of energy carriers on the equivalent basis [14,15]. Open literature has been searched for background studies of biomass, solar or electrical energy based building heating. Stritih and Butala [7] illustrated the performance of a biomass boiler with thermal storage for buildings. The TRNSYS program package was used to make system and mathematical models. As a result efficiency was calculated. Also, it is found that the heat was stored at the best exergy degree, and water mixing was a condition for optimizing the thermal storage. Jablonski et al. [16] designed a framework using market segmentation techniques for biomass heat demand in UK residential sector. It was found that the demand for bio-heat in the UK residents was between 3% and 31% of the total energy consumed in the heat market. Vallios et al. [8] presented a method for design of biomass district heating systems considering building structure and urban settlement around the plant. Biomass burning-district heating system was investigated along with energy, environmental and economic evaluations. Verma et al. [17] studied on comparative evaluation

1017

of several existing quality labels and standards for small scale biomass heating systems and the biomass fuels. It was determined that, quality labeling of both biomass heating systems and fuels leads to stricter emissions, efficiency and safety requirements as compared to European Union standards. Some measures supporting green energy market in the several countries in Europe were searched. As a result, the policies and incentives in France and Germany were the best. Meehan and McDonnell [18] identified potential sources of biomass within the catchment zone with different cases (case I: 10% biomass, case II: 50–100% biomass, and case III: environmental). The results showed that maximum energy production was obtained from case II in which generated within the catchment zone using 50–100% of biomass. Huang et al. [11] designed a system to meet the energy requirements of buildings and district heating/cooling applications. The biomass downdraft gasifier was used for the simulated trigeneration plant (commercial building). A simulation package was considered to use energy resources efficiently. Also, effects of biomass, such as rice husk, willow, etc., on the performance of the system were investigated. Fraisse et al. [19] studied on a combination of solar collector and direct solar floor heating system. It was found that the annual photovoltaic cell efficiency was 6.8% which represented a decrease of 28% in comparison with a conventional non-integrated PV module of 9.4% annual efficiency. Also, without a glass cover, the efficiency was 10%. Zhai et al. [20] worked on heating of the 460 m2 building using the solar collectors with an area of 150 m2. It is determined that the solar-powered floor heating system had a good potential in energy conservation in winter. The solar fraction was 56% for heating period, and the performance could be enhanced with the solar insolation increasing. Balta et al. [21] studied on seven heating applications for a building of 392 m3. Low exergy (LowEx) analysis and sustainability index were performed and it was calculated that overall exergy efficiencies of heating systems were range from 2.8% to 25.3%. Hepbasli [22] reviewed the studies conducted on LowEx heating and cooling systems for buildings. Some of them included biomass, electrical or solar collector heating systems. It was found that the exergy efficiency rates of the LowEx heating and cooling systems for buildings were calculated to range from 0.40% to 25.3%. The objectives of this study are to apply the energy, exergy, sustainability, environmental, exergoenvironmental, enviroeconomic, and exergoenviroeconomic analyses to various energy options for building floor heating, and to compare them. In this regard, this study differs from the previously conducted ones as follows: (i) biomass, solar and electrical energy options are considered for building heating, (ii) various reference (dead state) temperatures are taken into account, (iii) sustainability indexes are determined, (iv) environmental and enviroeconomic effects are presented, and (v) new analysis methods with different new formulations, which are named as “exergoenvironmental analysis” and “exergoenviroeconomic analysis”, are applied to the systems.

2. System description The building considered here has 120 m2 floor areas and 360 m3 volumes, while its indoor temperature is 21 1C and outdoor temperature is changing from 4 1C to 7.5 1C. Some specification of the building are listed in Table 1, while some necessary data for the analysis are given in Table 2. There is a floor heating system to heat the building. Also, the energy options are considered as biomass, solar and electrical energy. The natural gas fired electrical energy option and biomass energy option are commonly used for building heating. So, the solar energy option is considered for alternative option to see the advantages and disadvantages of the heating systems. The general schematic

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H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

layout of the biomass, solar and electrical energy options based building heating is illustrated in Fig. 1, while the generation parameters of the energy options for the building are tabulated in Table 3. Table 1 Some specification of the building. Building structure

Building outside wall

Building outside window

Building outside door Building roof Building ground

Area (m2)

South wall North wall East wall West wall South window North window East window West window

30.00 30.00 36.00 36.00 6.00

Transmittance (W/m2 K)

Temperature correction factor ()

0.13 0.85 0.27 0.17 0.80

1 1 0.5 1 1

6.00 0.80

1

9.00 0.90

1

9.00 1.20

1

3.75 0.80

1

120.00 0.16 120.00 0.26

Biomass is a kind of organic matter and generally as a form of solar energy captured by the plants. Wood, waste organic material, agricultural residues, energy crops, straw and sewage sludge are some of the examples of biomass. The plants absorb CO2 in addition to solar energy. So, utilization of biomass fuels completes the carbon cycle. It is low carbon compared to traditional fuels releasing CO2. Biomass heating system burns biomass to produce heat and send it wherever it is needed for various building heating. Also, biomass technology can be variable in size from the small wood burning stove for space heating in a building to the Table 3 Generation parameters of the energy options for the building. Parameter

Efficiency, ηG (  ) Primary energy factor source, FP (  ) Quality factor of source, Fq,S (  ) Max. supply temperature, qS,max (1C) Auxiliary energy, paux,ge (W/kWheat) Auxiliary energy, paux,ge,const (W) Part. environmental energy, Frenew (  )

1 0.6

Biomass

0.65 0.10 0.95 70.00 1.80 20.00 0.90

Solar collector

Electrical boiler

0.70 –

0.98 3.00

0.23 80.00 0.01 – 1.00

1.00 100.00 0.02 – –

Table 2 Some necessary data for the analysis. Data

Value

Data

Value

Inlet air temperature (1C) Outlet air temperature (1C) Building volume (m³) Building floor area (m2) Air exchange rate (1/h) Heat exchanger efficiency (%) Number of occupants (  ) Emitted heat per occupant (W) Specific internal gains of equipment (W/m²) Specific lighting power (W/m²) Storage system efficiency (%) Auxiliary energy factor of storage system (W/kWheat) Distribution system efficiency (%) Solar transmittance (  ) Solar radiation (south and north) (W/m²) Solar radiation (east and west) (W/m²)

21 4–7.5 360 120 0.6 80 5 80 1.362 2 95 2 96 0.42 20 50

Auxiliary energy factor of the distribution system (W/kWheat) Inlet temperature of floor heating system (1C) Return temperature of floor heating system (1C) Maximum heat emission of floor heating system (W/m2) Floor heating system efficiency (%) Specific ventilation power (W h/m³) Specific heat of the water (kJ/kg K) Density of the water (kg/m3) Dead state (reference) temperature (1C) Heating temperature (1C) Quality factor of the room air (  ) Quality factor of the air at the heater (  ) Temperature drop for distribution system (1C) Inlet temperature of the distribution system (1C) Temperature drop for storage system (1C) Solar correction factors (  )

8.94 35 30 80 99 0.54 4.2 1000 4–7.5 26.66 0.06 0.07 5 35 2 0.9

Fig. 1. General schematic layout of the biomass, solar and (natural gas fired) electrical energy options based building heating.

H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

boiler used to power a community heating scheme that heats a lot of buildings [23]. Solar collector takes the sunlight and converts it into heat. The absorber with selective surface coating allows it to convert solar radiation into heat energy efficiently. The collectors have tempered glass for protection. Collectors can be mounted on a roof or as a part of building façade. Solar collectors can be used with short term or seasonal storage units. Short term storage units can store solar heat for several days, while seasonal storage units can retain heat for weeks [13].

3. Analysis Energy, exergy, sustainability, environmental, exergoenvironmental, enviroeconomic, and exergoenviroeconomic analyses are chosen and developed to assess the system with a large perspective of thermodynamics. Here, low exergy approach is used for energy and exergy analyses. Fossil fuels, which are common energy carriers, deliver high valued energy. On the other hand, sustainable energy sources (such as waste heat (biomass), solar collector, heat pumps, energy storage, etc.) deliver low valued energy. Exergy is the thermodynamic concept that generally known as a qualitative value of energy (e.g. heat, electricity, mechanical workload). If energy is completely convertible into other types of energy, it is known as exergy which is high valued energy. If the energy has limited converted part, it is named as “low valued energy” (e.g. heat close to room temperature). This low valued energy is used for low exergy heating systems of buildings [24,25]. 3.1. Energy analysis

Q_ OHL ¼ Q_ THL þ Q_ VHL þ Q_ SHL þ Q_ IG þ Q_ EE þ Q_ LP þ Q_ V P þ Q_ DHW þ Q_ PT ð1Þ where “Q_ THL ”, “Q_ VHL ”, “Q_ SHL ”, “Q_ IG ”, “Q_ EE ”, “Q_ LP ”, “Q_ VP ”, “Q_ DHW ” and “Q_ PT ” are the heat loss rate due to transmission (W), the ventilation heat loss rate (W), the system heat loss rate (W), the inefficient generation rate (W), the electrical energy rate (W), the lighting power (W), the ventilation electrical energy rate (W), the Domestic Hot Water (DHW) energy rate (W) and the primary energy transformation rate (W). The heat loss rate due to transmission ðQ_ THL Þ is found by ð2Þ

where “Q_ T;w ”, “Q_ T;r ”, “Q_ T;g ” and “Q_ T;wall ” are the heat losses rates due to transmission through windows, roof, ground and walls, respectively. The heat loss rate due to transmission through windows ðQ_ T;w Þ is calculated as follows: Q_ T;w ¼ ∑ðU i Ai F xi Þw ðT i  T 0 Þ

ð3Þ

where “U i ”, “Ai ”, “F xi ”, “T i ” and “T 0 ” are thermal transmittance (W/ m2 K), area (m2), temperature correction factor (  ), the building room (inlet) temperature (1C or K) and the outlet (environment) temperature (1C or K), respectively. Also, subscript “w” means “window”. The heat loss rate due to transmission through roof ðQ_ T;r Þ is obtained as Q_ T;r ¼ ∑ðU i Ai F xi Þr ðT i  T 0 Þ where subscript “r” means “roof”.

The heat loss rate due to transmission through ground ðQ_ T;g Þ is determined by Q_ T;g ¼ ∑ðU i Ai F xi Þg ðT i  T 0 Þ

ð5Þ

where subscript “g” means “ground”. The heat loss rate due to transmission through walls (and doors) ðQ_ T;wall Þ is computed as: Q_ T;wall ¼ ∑ðU i Ai F xi Þwall ðT i  T 0 Þ

ð6Þ

The ventilation heat loss rate ðQ_ V HL Þ is calculated as follows: 
 Q_ V HL ¼ cp ρVnd 1  ηV ðT i  T o Þ ð7Þ where “cp ” is the specific heat capacities of the air in the building (kJ/kg K), “ρ” is the density of the air in the building, “V” is the volume (inside) of the building (m3), “nd” is the air exchange rate (1/h) and “ηV ” is the heat exchanger efficiency. The system heat loss rate ðQ_ SHL Þ is expressed as Q_ SHL ¼ Q_ HL;e þ Q_ HL;d þ Q_ HL;s

ð8Þ

where “Q_ HL;e ”, “Q_ HL;d ”, and “Q_ HL;s ” are emission, distribution and storage heat losses rates (W), respectively. The emission heat loss rate ðQ_ HL;e Þ is determined by   1 Q_ HL;e ¼ Q_ HD 1 ð9Þ ηe where“Q_ HD ” is the head demand rate (W) and “ηe ” is the emission system efficiency (%). The distribution heat loss rate ðQ_ HL;d Þ is found as follows:    1 Q_ HL;d ¼ Q_ HD þ Q_ HL;e 1 ð10Þ ηd where “ηd ” is the distribution system efficiency (%). The storage heat loss rate ðQ_ HL;s Þ is determined from    1 1 Q_ HL;s ¼ Q_ HD þ Q_ HL;e þ Q_ HL;d ηs

The overall heat loss rate ðQ_ OHL Þ can be written as follows:

Q_ THL ¼ Q_ T;w þ Q_ T;r þ Q_ T;g þ Q_ T;wall

1019

ð4Þ

where “ηs ” is the storage system efficiency (%). The head demand rate ðQ_ HD Þ can be written as   Q_ HD ¼ Q_ THL þ Q_ V HL  Q_ SHG þ Q_ IHG;occ þ Q_ IHG;eq þ Q_ LP

ð11Þ

ð12Þ

where “Q_ SHG ”, “Q_ IHG;occ ”, “Q_ IHG;eq ” and “Q_ LP ” are the solar heat gain rate (W), the internal heat gain rate of occupants (W), the internal heat gain rate of equipment (W) and the lighting power (W), respectively. The solar heat gain rate ðQ_ SHG Þ is expressed by
 ð13Þ Q_ SHG ¼ ∑I S;j 1  F f Aw;j g j F sh F no where “I S;j ” is the solar radiation (W/m2), “F f ” is the window frame fraction, “Aw;j ” is the window area (m2), “g j ” is the total energy transmittance (  ). Also, “F sh ” and “F no ” are corrections factors as 0.9 for shading and 0.9 for not orthogonal radiation. The internal heat gain rate of occupants ðQ_ IHG;occ Þ is obtained from ″ Q_ IHG;occ ¼ nocc Q_ i;occ

ð14Þ ″ “Q_ i;occ ”

where “nocc ” is the number of occupants (  ) and is the emitted heat per occupant (W). The internal heat gain rate of equipment ðQ_ IHG;eq Þ is expressed as follows: ″ Q_ IHG;eq ¼ Q_ i;eq AN ″ “Q_ i;eq ”

ð15Þ

is the specific internal gains of equipment (W/m²) where and “AN ” is the net floor area (m2).

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H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

The lighting power ðQ_ LP Þ is calculated as Q_ LP ¼ pL AN

ð16Þ

where “pL ” is the specific lighting power (W/m²). The inefficient generation rate ðQ_ IG Þ is obtained from   ð1  F Þ s 1 Q_ IG ¼ Q_ HD þ Q_ HL;e þ Q_ HL;d þ Q_ HL;s ηB

The required energy rate of the generation ðQ_ REG Þ is calculated as follows:  ð1  F Þ s Q_ REG ¼ Q_ HD þ Q_ HL;e þ Q_ HL;d þ Q_ HL;s ð26Þ ηB The overall energy gain rate ðE_ OEG Þ is written as follows:

ð17Þ

E_ OEG ¼ E_ SEG þ E_ IHG þ E_ renew þ E_ PE

ð27Þ

where “F s ” is the solar fraction (storage) (  ) and “ηB ” is the generation/conversion efficiency (%). The electrical energy rate (ðQ_ EE Þ) is computed as

where “E_ SEG ” is the solar energy gain rate (W), “E_ IHG ” is the internal heat gain rate (W) and “E_ PE ” is the primary energy rate (W). The solar energy gain rate ðE_ SEG Þ is determined as

Q_ EE ¼ P aux;E þ P aux;D þP aux;S þ P aux;G

E_ SEG ¼ Q_ SHG

ð18Þ

where “P aux;E ”, “P aux;D ”, “P aux;S ” and “P aux;G ” are the auxiliary energy rates of the emission, distribution, storage and generation systems (W), respectively. The auxiliary energy rate of the emission system ðP aux;E Þ is determined as follows: P aux;E ¼ paux;E

Q_ HD

ð19Þ

where “paux;E ” is the auxiliary energy factor of the emission system (radiator) (W/kWheat). The auxiliary energy rate of the distribution system ðP aux;D Þ is found from  ð20Þ P aux;D ¼ paux;D Q_ HD þ Q_ HL;e where “paux;D ” is the auxiliary energy factor of the distribution system (W/kWheat). The auxiliary energy rate of the storage system ðP aux;S Þ is computed as  P aux;S ¼ p ð21Þ þ Q_ Q_ þ Q_ aux;S

HD

HL;e

HL;d

where “paux;S ” is the auxiliary energy factor of the storage system (W/kWheat). The auxiliary energy rate of the generation system ðP aux;G Þ is expressed by  P aux;G ¼ paux;G Q_ HD þ Q_ HL;e þ Q_ HL;d þ Q_ HL;s þ paux;G;const ð22Þ where “paux;G ” is the auxiliary energy factor of the generation/ conversion system (W/kWheat) and “paux;G;const ” is the constant auxiliary energy rate of the generation/conversion system (W). The ventilation electrical energy rate (power) ðQ_ V P Þ is defined as Q_ V P ¼ pv V nd

ð23Þ

where “pv ” is the specific ventilation power (W h/m³). The domestic hot water energy rate ðQ_ DHW Þ is determined from
 V w cp;w ρw T sup T in w nocc ð24Þ Q_ DHW ¼ ηG;DHW

ð28Þ

The internal heat gain rate ðE_ IHG Þ is computed by E_ IHG ¼ Q_ IHG;occ þ Q_ IHG;eq þ Q_ LP

ð29Þ

The additional renewable energy input rate ðE_ renew Þ is found as E_ renew ¼ Q_ REG F renew

ð30Þ

where “F renew ” is the partial environmental energy factor (  ). There is no renewable energy input, so “F renew ” is equal to zero (0). The primary energy rate (required primary energy input rate ðE_ prim;tot Þ ðE_ PE Þ is expressed as follows:  E_ PE ¼ E_ prim;tot ¼ Q_ REG F P þ Q_ LP þ Q_ VP þ P aux;E þ P aux;D þ P aux;S þ P aux;G F PEE þ Q_ DHW F P;DHW

ð31Þ

The energy efficiency of the building ðηbuild Þ is written as ! ! Q_ HD Q_ HD ηbuild ¼ 100 ¼ 100 ð32Þ E_ PE E_ prim;tot Including the renewable energy input rate ðE_ renew Þ, the overall energy efficiency of the building ðηbuild;overall Þ can be determined by ! Q_ HD 100 ð33Þ ηbuild;overall ¼ E_ prim;tot þ E_ renew

3.2. Exergy analysis _ Envlp Þ The exergy demand rate of the envelope of the building ðEx _ room Þ as follows: is equal to the exergy load rate of the room ðEx _ _ _ Ex Envlp ¼ Exroom ¼ Q HD F q;room

ð34Þ

where “F q;room ” is the quality factor of the room air (  ) as given by F q;room ¼ 1 

To Ti

_ Room The exergy demand rate of the room air ðEx written as _ Room Ex

air

_ heat  Ex _ Envlp ¼ Ex

ð35Þ air Þ

is

ð36Þ

where “V w ” is the flow rate of the DHW (l/day or l/s), “cp;w ” is the specific heat of the water (kJ/kg K), “ρw ” is the density of the water (kg/m3), “T sup ” is the water supply temperature (1C or K), “T in ” is the water inlet temperature (1C or K) and “ηG;DHW ” is the efficiency of the DHW production system (%). The primary energy transformation rate ðQ_ PT Þ is expressed by
  Q_ PT ¼ Q_ REG F p  1 þ Q_ LP þ Q_ V P þ P aux;E þ P aux;D þ P aux;S þ P aux;G
 ðF PEE 1Þ þ Q_ DHW F P;DHW  1 ð25Þ

_ heat ” is the exergy load rate at heater (W) and it is where “Ex expressed by

where “Q_ REG ” is the required energy rate of generation (W), “F p ” is the primary energy factor source for generation/conversion system (  ), “F PEE ” is the primary energy factor of electricity ( ) and “F P;DHW ” is the primary energy factor source for DHW system (  ).

ð39Þ

_ heat ¼ Q_ HD F q;heater Ex

ð37Þ

where “F q;heater ” is the quality factor of the air at the heater (  ). F q;heater ¼ 1 

To T heat

where “T heat ” is the heating temperature (K) as follows:   T in  T ret 1  þTi T heat ¼
ln ðT in  T i Þ=ðT ret  T i Þ 2

ð38Þ

where “T in ” and “T ret ” are the inlet and return temperatures of the heating system (K), respectively.

H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

_ D;Emiss Þ is The exergy demand rate of the emission system ðEx computed by _ emiss þ P aux;E _ D;Emiss ¼ ΔEx Ex

ð40Þ

_ emiss ” is the net exergy demand rate of the emission where “ΔEx system (W) as    Q_ HD þ Q_ HL;e

T in _ emiss ¼ ΔEx ðT in  T ret Þ  T ref ln ð41Þ ðT in  T ret Þ T ret where “T ref ” is the reference temperature (K) and it is equal to outlet temperature of the building ðT o Þ. _ D;Dis Þ is The exergy demand rate of the distribution system ðEx determined from _ _ D;Dis ¼ ΔEx Ex dis þ P aux;D

ð42Þ

_ dis ” is the net exergy demand rate of the distribution where “ΔEx system (W).

  _ T dis _ dis ¼ Q HL;d T dis  T ref ln ð43Þ ΔEx ΔT dis T dis  ΔT dis

1021

building (W) and “F q;renew ” is the quality factor of the source for the renewable energy ( ). _ SHG Þ is written as The solar exergy supply rate of the building ðEx follows: _ SHG ¼ Q_ SHG F ex;solar Ex

ð51Þ

where “F ex;solar ” is the exergetic solar heat gain factor (e.g. 0.9). _ IHG Þ is The internal exergy supply rate of the building ðEx computed as    _ IHG ¼ Q_ IHG;occ 1  T o ð52Þ Ex 310 where “T o ” is the outlet temperature of the building (K). _ renew Þ is The renewable exergy supply rate of the building ðEx calculated from _ renew ¼ E_ renew F q;renew Ex

ð53Þ

_ PEx Þ is expressed by The primary exergy rate of the building ðEx _ _ _ PEx ¼ Q_ Ex REG F P F q;S þ ðQ LP þ Q VP þ P aux;E þ P aux;D þ P aux;S þ P aux;G Þ _ ð54Þ F PEE F q;elec þ Q DHW F P;DHW F q;s;DHW

where “T dis ” is the inlet temperature of the distribution system (mean design temperature) (K) and “ΔT dis ” is the temperature drop for distribution system (K). _ D;Stor Þ is The exergy demand rate of the storage system ðEx obtained as

The exergy efficiency of the building ðΨ build Þ can be found as ! _ room Ex 100 ð55Þ Ψ build ¼ _ tot Ex

_ stor þ P aux;S _ D;Stor ¼ ΔEx Ex

3.3. Sustainability analysis

ð44Þ

_ stor ” is the net exergy demand rate of the storage where “ΔEx system (W) as follows:

  _ _ stor ¼ Q HL;s ΔT stor  T ref ln T dis þ ΔT dis þΔT dis  ΔT stor ð45Þ ΔEx ΔT stor T dis where “ΔT stor ” is the temperature drop for storage system (K). _ D;Ge Þ is The exergy demand rate of the generation system ðEx calculated by  _ ge þ Ex _ plant _ D;Ge ¼ Ex Ex  _ dis þ P aux;D þ ΔEx _ emis þ P aux;E þ Ex _ heat _ stor þP aux;S þ ΔEx  ΔEx ð46Þ _ ge ” is the exergy load rate of the generation system where “Ex _ plant ” is the exergy load rate of the plant (W). (W) and “Ex _ ge Þ can be The exergy load rate of the generation system ðEx determined from _ ge ¼ Q_ REG F q;S Ex

ð47Þ

where “F q;S ” is the quality factor of the source for the generation/ conversion system (  ). _ plant Þ is found from The exergy load rate of the plant ðEx  _ plant ¼ Q_ LP þ Q_ V P F q;elec þ Q_ DHW F q;s;DHW Ex ð48Þ where “F q;elec ” and “F q;s;DHW ” are the quality factor of the source for the electricity and the DHW production system ( ), respectively. _ PEx Þ is computed as The primary exergy rate of the building ðEx  _ tot  Ex _ ge  Ex _ plant _ PEx ¼ Ex ð49Þ Ex _ tot ” is the total exergy input rate of the building (W). where “Ex _ tot Þ is determined The total exergy input rate of the building ðEx by _ _ _ tot ¼ Q_ Ex REG F P F q;S þ ðQ LP þ Q VP þP aux;E þ P aux;D þ P aux;S þ P aux;G Þ ð50Þ F PEE F q;elec þ Q_ DHW F P;DHW F q;s;DHW þ E_ renew F q;renew where “E_ renew ” is the additional renewable energy input rate of the

Sustainability is known as a key to solve current economic, ecological and developmental problems. It may be defined in terms of carrying capacity of the ecosystem, and described with input–output models of energy consumption. Also, sustainability can become an economic state where the demands placed on the environment by people and commerce can be met without reducing the capacity of the environment to provide for future generations. Sustainability can be improved by exergy methodology which is essential in improving efficiency, and allows society to maximize the benefits it derives from its resources while minimizing the negative impacts. In this regard, sustainable development entails to utilize the resources efficiently. More efficiency in utilization enables resources to contribute to development over a longer period of time. Sustainability assessment defined with sustainability index (SI) which is related with exergy efficiency ðΨ Þ as follows [14]: SI ¼

1 1Ψ

ð56Þ

3.4. Environmental analysis The environmental performance of processes or products is a major issue about reducing the effects on environment. So, life cycle assessment (LCA) is generally chosen for this purpose. This methodology considers the entire life cycle of a product. LCA is a product-oriented tool to analyze the environmental impacts that a specific product, process or service causes [26]. In this study, environmental impact assessment of the building floor heating with biomass, solar and electrical energy options is calculated according to their LCA based CO2 emissions and energy rates. The biomass material is considered as softwood that burns in the biomass boiler for floor heating. The value of CO2 is 0.023 kg-CO2/kW h for this biomass material [26]. Also, the solar energy option is considered as solar collector for floor heating. According to LCA, some amount of CO2 is released during flat plate solar collector manufacturing. Including its energy saved, the estimated CO2 value for flat plate solar collector is 0.00647

1022

H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

kg-CO2/kW h [27]. Furthermore, it is assumed that the electrical supported boiler takes its energy from natural gas fired electricity station. So, the CO2 value for this electricity is 0.712 kg-CO2/kW h [26]. The environmental impact assessment of the system can be calculated to be [28]: _ energy t working xCO2 ¼ yCO2 W

ð57Þ

where “xCO2 ” is the CO2 emission releasing in a period of time (kg-CO2/time), “yCO2 ” is the CO2 emission value for the energy _ energy ” is the energy rate of the energy option (kg-CO2/kW h), “W option (kW) and “t working ” is working hours of the related system (h/time). As is seen that environmental analysis requires the energy _ energy Þ is analysis. Because the energy rate of the energy options ðW found from complete energy analysis. The combining this with the LCA parameter gives the environmental result.

3.5. Exergoenvironmental analysis New exergoenvironmental analysis is applied considering exergetic value and greenhouse gas emissions rate as follows: _ en:option t xexCO2 ¼ yCO2 Ex working

ð58Þ

where “xexCO2 ” is the exergetic CO2 emission releasing in a period of time (kg-CO2/time), “yCO2 ” is the CO2 emission value for the energy _ en:option ” is the related exergy rate of the option (kg-CO2/kW h), “Ex energy option (kW) and “t working ” is working hours of the related system (h/time). The exergoenvironmental equation explains CO2 emission releasing of an energy option including exergetic values. Before exergoenvironmental analysis, the detailed exergy analysis is _ en:option Þ. necessary to obtain exergy rate of the energy option ðEx Also, the LCA parameter is taken into account to complete the exergetic based environmental analysis.

3.6. Enviroeconomic analysis It is considered that the enviroeconomic analysis can be calculated with contribution of the CO2 emission price and its released quantity. Greenhouse gases may be minimized by carbon price establishing in terms of realizing the situation. The payment for emission carbon is a kind of method for motivating people and countries to reduce carbon emissions. It also provides an incentive to invest and deploy new energy technologies that do not release carbon to the atmosphere. The international carbon price is between 0.013 $/kg-CO2 and 0.016 $/kg-CO2 [29]. In this regard, the carbon price can approximately be taken as 0.0145 $/kg-CO2 [28]. The released CO2 quantity ðxCO2 Þ is found from environmental analysis. Including the CO2 emission price ðcCO2 Þ, the enviroeconomic cost parameter “C CO2 ” ($/time) can be determines as follows: C CO2 ¼ xCO2 cCO2

ð59Þ

The enviroeconomic analysis requires complete energy and environmental analyses. In addition, economic rate of the greenhouse gas is necessary to achieve enviroeconomic rate.

3.7. Exergoenviroeconomic analysis Exergoenviroeconomic analysis is another analysis method first performed here to a case study. It bases on exergoenvironmental analyses result ðxexCO2 Þ and greenhouse gas emission price ðcCO2 Þ as

follows: C exCO2 ¼ xexCO2 cCO2

ð60Þ

where “C exCO2 ” is the exergoenviroeconomic parameter ($/time). This analysis is similar to enviroeconomic analysis method, but the difference is that only exergetic value is used here. As is known, exergy is the quality of energy and it is useful part of the energy. So, considering the exergetic values with the environmental and economic parameters can give better reliable results. So, complete exergy and exergoenvironmental analyses are required for this analysis.

4. Results and discussion The energy analysis results of the biomass energy option based building heating are tabulated in Table 4. The most of the energy is lost in the generation part of the biomass supported system for all of the reference environment temperatures. The total energy (input) rates of the biomass supported building are found as 1347.53 W, 1334.50 W, 1321.47 W, 1308.44 W, 1295.41 W, 1282.38 W, 1269.35 W, and 1256.32 W for the 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C reference temperatures, respectively. According to energy analysis, there is no energy loss after the heating system. The maximum energy loss rates (the generation part of the system) are determined as 997.31 W, 960.14 W, 922.98 W, 885.81 W, 848.64 W, 811.48 W, 774.31 W, and 737.15 W for the 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C reference temperatures, respectively. There is also primary energy transform (energy gain) rate to the system as 810.15 W, 716.53 W, 622.92 W, 529.30 W, 435.68 W, 342.06 W, 248.45 W, and 154.83 W for the 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C reference temperatures, respectively. The exergy analysis results of the biomass energy option based building heating are given in Table 5. The maximum exergy lost occurs in the generation part of this system for all of the dead state temperatures. They are calculated as 1837.53 W, 1752.25 W, 1666.53 W, 1580.38 W, 1493.80 W, 1406.79 W, 1319.35 W, and 1231.47 W for the dead state temperatures of 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C, respectively. The total exergy (input) rates of the biomass supported system are computed as 1338.70 W, 1326.19 W, 1313.69 W, 1301.19 W, 1288.69 W, 1276.19 W, 1263.69 W, and 1251.19 W for the dead state temperatures of 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C, respectively. In addition to this total exergy (input), there is primary exergy transform (exergy gain) rate to the system as 696.99 W, 608.96 W, 520.92 W, 432.88 W, 344.84 W, 256.80 W, 168.76 W, and 80.72 W for the dead state temperatures of 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C, respectively. The energy analysis results of the solar energy option based (flat plate collector) building heating are tabulated in Table 6. The generation part of the solar energy supported system has maximum energy loss for all of the reference environment temperatures. The values of the generation heat losses are found as 849.00 W, 819.52 W, 790.04 W, 760.56 W, 731.07 W, 701.59 W, 672.11 W, and 642.63 W for the 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C reference temperatures, respectively. The total energy (input) rates of the solar energy supported building are determined to be 1104.62 W, 1102.54 W, 1100.47 W, 1098.39 W, 1096.31 W, 1094.23 W, 1092.15, and 1090.08 W for the 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C reference temperatures, respectively. There is no heat (energy) loss after the heating system. The primary energy transform (gain) rates of this solar supported system are 904.76 W, 807.88 W, 710.99 W, 614.10 W, 517.21 W, 420.32 W, 323.44 W, and 226.55 W for the 4 1C, 4.5 1C,

H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

1023

Table 4 Energy analysis results of the biomass energy option based building heating. Temperature (1C)

Number of part**(  )

Flow parts

4

1

Input

2

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

4.5

3 4 5 6 7 8 1 2

5

3 4 5 6 7 8 1 2

5.5

3 4 5 6 7 8 1 2

6

3 4 5 6 7 8 1 2

6.5

3 4 5 6 7 8 1 2

7

3 4 5 6 7 8 1 2

7.5

3 4 5 6 7 8 1 2 3 4

Heat energy rate Electrical energy (W) rate (W)

Total energy rate Energy loss (or gain) (W) rate (W)

Part explanation

176.74

1170.79

1347.53

 810.15*

1767.42

390.26

2157.69

997.31

Primary energy transform Generation

1148.82 1091.38 1048.16 1037.68 1037.68 1037.68 166.16

11.56 9.37 0.00 0.00 0.00 0.00 1168.34

1160.38 1100.76 1048.16 1037.68 1037.68 1037.68 1334.50

59.62 52.59 10.48 0.00 0.00

Storage Distribution Heating Room air Envelope

 716.53*

1661.59

389.45

2051.04

960.14

Primary energy transform Generation

1080.03 1026.03 985.40 975.55 975.55 975.55 155.58

10.86 8.81 0.00 0.00 0.00 0.00 1165.90

1090.90 1034.84 985.40 975.55 975.55 975.55 1321.47

56.05 49.44 9.85 0.00 0.00

Storage Distribution Heating Room air Envelope

 622.92*

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

1555.76

388.63

1944.39

922.98

Primary energy transform Generation

1011.24 960.68 922.64 913.41 913.41 913.41 144.99

10.17 8.25 0.00 0.00 0.00 0.00 1163.45

1021.41 968.93 922.64 913.41 913.41 913.41 1308.44

52.48 46.29 9.23 0.00 0.00

Storage Distribution Heating Room air Envelope

 529.30*

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

1449.92

387.82

1837.74

885.81

Primary energy transform Generation

942.45 895.33 859.87 851.27 851.27 851.27 134.41

9.48 7.69 0.00 0.00 0.00 0.00 1161.00

951.93 903.02 859.87 851.27 851.27 851.27 1295.41

48.91 43.14 8.60 0.00 0.00

Storage Distribution Heating Room air Envelope

 435.68*

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

1344.09

387.00

1731.09

848.64

Primary energy transform Generation

873.66 829.98 797.11 789.14 789.14 789.14 123.83

8.79 7.13 0.00 0.00 0.00 0.00 1158.55

882.45 837.10 797.11 789.14 789.14 789.14 1282.38

45.34 40.00 7.97 0.00 0.00

Storage Distribution Heating Room air Envelope

 342.06*

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

1238.26

386.18

1624.44

811.48

Primary energy transform Generation

804.87 764.63 734.35 727.00 727.00 727.00 113.24

8.10 6.57 0.00 0.00 0.00 0.00 1156.11

812.96 771.19 734.35 727.00 727.00 727.00 1269.35

41.77 36.85 7.34 0.00 0.00

Storage Distribution Heating Room air Envelope

 248.45*

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

1132.43

385.37

1517.80

774.31

Primary energy transform Generation

736.08 699.27 671.58 664.87 664.87 664.87 102.66

7.40 6.01 0.00 0.00 0.00 0.00 1153.66

743.48 705.28 671.58 664.87 664.87 664.87 1256.32

38.20 33.70 6.72 0.00 0.00

Storage Distribution Heating Room air Envelope

 154.83*

After primary energy transformation After boiler After storage

1026.59

384.55

1411.15

737.15

Primary energy transform Generation

667.29 633.92

6.71 5.44

674.00 639.37

34.63 30.55

Storage Distribution

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

1024

H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

Table 4 (continued ) Temperature (1C)

n

Number of part**( )

Flow parts

5 6 7 8

After After After After

Heat energy rate Electrical energy (W) rate (W)

distribution heating system room envelope

608.82 602.73 602.73 602.73

0.00 0.00 0.00 0.00

Total energy rate Energy loss (or gain) (W) rate (W) 608.82 602.73 602.73 602.73

6.09 0.00 0.00

Part explanation

Heating Room air Envelope

Energy gain. Number of part is connected with Sankey/Grassmann diagram.

nn

Table 5 Exergy analysis results of the biomass energy option based building heating. Temperature (1C) 4

1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

4.5

5

5.5

6

6.5

7

7.5

n

Number of part**( )

Flow parts Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope

Total exergy rate (W)

transformation

transformation

transformation

transformation

transformation

transformation

transformation

transformation

Exergy gain. Number of part is connected with Sankey/Grassmann diagram.

nn

1338.70 2035.69 198.16 189.54 176.14 78.42 59.97 0.00 1326.19 1935.15 182.90 174.88 162.35 72.10 54.72 0.00 1313.69 1834.61 168.08 160.65 148.98 65.99 49.68 0.00 1301.19 1734.07 153.69 146.84 136.02 60.08 44.86 0.00 1288.69 1633.53 139.72 133.45 123.47 54.38 40.24 0.00 1276.19 1532.99 126.19 120.48 111.33 48.88 35.84 0.00 1263.69 1432.45 113.10 107.93 99.61 43.59 31.64 0.00 1251.19 1331.90 100.43 95.80 88.30 38.52 27.66 0.00

Exergy loss (or gain) rate (W)

Part explanation

*

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

 608.96* 1752.25 8.02 12.53 90.25 17.38 54.72

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

 520.92* 1666.53 7.43 11.67 82.99 16.30 49.68

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

 432.88* 1580.38 6.85 10.82 75.94 15.22 44.86

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

 344.84* 1493.80 6.28 9.98 69.09 14.13 40.24

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

 256.80* 1406.79 5.72 9.14 62.45 13.04 35.84

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

 168.76* 1319.35 5.17 8.32 56.02 11.95 31.64

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

 80.72* 1231.47 4.63 7.50 49.78 10.85 27.66

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

 696.99 1837.53 8.62 13.40 97.71 18.45 59.97

H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

1025

Table 6 Energy analysis results of the solar energy option based building heating. Temperature (1C)

Number of part**(  )

Flow parts

4

1

Input

2

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

4.5

3 4 5 6 7 8 1 2

5

3 4 5 6 7 8 1 2

5.5

3 4 5 6 7 8 1 2

6

3 4 5 6 7 8 1 2

6.5

3 4 5 6 7 8 1 2

7

3 4 5 6 7 8 1 2

7.5

3 4 5 6 7 8 1 2 3 4 5

Heat energy rate Electrical energy (W) rate (W)

Total energy rate Energy loss (or gain) (W) rate (W)

Part explanation

1104.62

1104.62

 904.76*

1641.18

368.21

2009.38

849.00

Primary energy transform Generation

1148.82 1091.38 1048.16 1037.68 1037.68 1037.68

11.56 9.37 0.00 0.00 0.00 0.00 1102.54

1160.38 1100.76 1048.16 1037.68 1037.68 1037.68 1102.54

59.62 52.59 10.48 0.00 0.00

Storage Distribution Heating Room air Envelope

 807.88*

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

1542.90

367.51

1910.42

819.52

Primary energy transform Generation

1080.03 1026.03 985.40 975.55 975.55 975.55

10.86 8.81 0.00 0.00 0.00 0.00 1100.47

1090.90 1034.84 985.40 975.55 975.55 975.55 1100.47

56.05 49.44 9.85 0.00 0.00

Storage Distribution Heating Room air Envelope

 710.99*

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

1444.63

366.82

1811.45

790.04

Primary energy transform Generation

1011.24 960.68 922.64 913.41 913.41 913.41

10.17 8.25 0.00 0.00 0.00 0.00 1098.39

1021.41 968.93 922.64 913.41 913.41 913.41 1098.39

52.48 46.29 9.23 0.00 0.00

Storage Distribution Heating Room air Envelope

 614.10*

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

1346.36

366.13

1712.49

760.56

Primary energy transform Generation

942.45 895.33 859.87 851.27 851.27 851.27

9.48 7.69 0.00 0.00 0.00 0.00 1096.31

951.93 903.02 859.87 851.27 851.27 851.27 1096.31

48.91 43.14 8.60 0.00 0.00

Storage Distribution Heating Room air Envelope

 517.21*

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

1248.09

365.44

1613.52

731.07

Primary energy transform Generation

873.66 829.98 797.11 789.14 789.14 789.14

8.79 7.13 0.00 0.00 0.00 0.00 1094.23

882.45 837.10 797.11 789.14 789.14 789.14 1094.23

45.34 40.00 7.97 0.00 0.00

Storage Distribution Heating Room air Envelope

 420.32*

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

1149.81

364.74

1514.56

701.59

Primary energy transform Generation

804.87 764.63 734.35 727.00 727.00 727.00

8.10 6.57 0.00 0.00 0.00 0.00 1092.15

812.96 771.19 734.35 727.00 727.00 727.00 1092.15

41.77 36.85 7.34 0.00 0.00

Storage Distribution Heating Room air Envelope

 323.44*

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

1051.54

364.05

1415.59

672.11

Primary energy transform Generation

736.08 699.27 671.58 664.87 664.87 664.87

7.40 6.01 0.00 0.00 0.00 0.00 1090.08

743.48 705.28 671.58 664.87 664.87 664.87 1090.08

38.20 33.70 6.72 0.00 0.00

Storage Distribution Heating Room air Envelope

 226.55*

After primary energy transformation After boiler After storage After distribution

953.27

363.36

1316.63

642.63

Primary energy transform Generation

667.29 633.92 608.82

6.71 5.44 0.00

674.00 639.37 608.82

34.63 30.55 6.09

Storage Distribution Heating

1026

H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

Table 6 (continued ) Temperature (1C)

n

Number of part**(  )

Flow parts

Heat energy rate Electrical energy (W) rate (W)

6 7 8

After heating system After room After envelope

602.73 602.73 602.73

0.00 0.00 0.00

Total energy rate Energy loss (or gain) (W) rate (W) 602.73 602.73 602.73

0.00 0.00

Part explanation

Room air Envelope

Energy gain. Number of part is connected with Sankey/Grassmann diagram.

nn

Table 7 Exergy analysis results of the solar energy option based building heating. Temperature (1C)

Number of part**(  )

Flow parts

4

1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope Input After primary exergy After boiler After storage After distribution After heating system After room After envelope

4.5

5

5.5

6

6.5

7

7.5

nn

transformation

transformation

transformation

transformation

transformation

transformation

transformation

transformation

Number of part is connected with Sankey/Grassmann diagram.

Total exergy rate (W)

Exergy loss (or gain) rate (W)

Part explanation

1104.62 734.11 198.16 189.54 176.14 78.42 59.97 0.00 1102.54 711.51 182.90 174.88 162.35 72.10 54.72 0.00 1100.47 688.91 168.08 160.65 148.98 65.99 49.68 0.00 1098.39 666.30 153.69 146.84 136.02 60.08 44.86 0.00 1096.31 643.70 139.72 133.45 123.47 54.38 40.24 0.00 1094.23 621.10 126.19 120.48 111.33 48.88 35.84 0.00 1092.15 598.49 113.10 107.93 99.61 43.59 31.64 0.00 1090.08 575.89 100.43 95.80 88.30 38.52 27.66 0.00

370.51 535.95 8.62 13.40 97.71 18.45 59.97

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

391.04 528.60 8.02 12.53 90.25 17.38 54.72

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

411.56 520.83 7.43 11.67 82.99 16.30 49.68

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

432.09 512.62 6.85 10.82 75.94 15.22 44.86

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

452.61 503.98 6.28 9.98 69.09 14.13 40.24

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

473.14 494.90 5.72 9.14 62.45 13.04 35.84

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

493.66 485.40 5.17 8.32 56.02 11.95 31.64

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

514.19 475.46 4.63 7.50 49.78 10.85 27.66

Primary exergy transform Generation Storage Distribution Heating Room air Envelope

H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

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Table 8 Energy analysis results of the electrical energy option based building heating. Temperature (1C)

Number of part**(  )

Flow parts

Heat energy rate Electrical energy (W) rate (W)

Total energy rate Energy loss (or gain) (W) rate (W)

Part explanation

4

1

Input

3516.81

1104.66

4621.47

3080.98

2

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input

1172.27

368.22

1540.49

380.11

Primary energy transform Generation

1148.82 1091.38 1048.16 1037.68 1037.68 1037.68 3306.22

11.56 9.37 0.00 0.00 0.00 0.00 1102.58

1160.38 1100.76 1048.16 1037.68 1037.68 1037.68 4408.80

59.62 52.59 10.48 0.00 0.00

Storage Distribution Heating system Room air Envelope

2939.20

1102.07

367.53

1469.60

378.70

Primary energy transform Generation

1080.03 1026.03 985.40 975.55 975.55 975.55 3095.64

10.86 8.81 0.00 0.00 0.00 0.00 1100.50

1090.90 1034.84 985.40 975.55 975.55 975.55 4196.14

56.05 49.44 9.85 0.00 0.00 2797.42

1031.88

366.83

1398.71

377.30

1011.24 960.68 922.64 913.41 913.41 913.41 2885.05

10.17 8.25 0.00 0.00 0.00 0.00 1098.42

1021.41 968.93 922.64 913.41 913.41 913.41 3983.47

52.48 46.29 9.23 0.00 0.00 2655.65

961.68

366.14

1327.82

375.89

942.45 895.33 859.87 851.27 851.27 851.27 2674.47

9.48 7.69 0.00 0.00 0.00 0.00 1096.34

951.93 903.02 859.87 851.27 851.27 851.27 3770.81

48.91 43.14 8.60 0.00 0.00 2513.87

891.49

365.45

1256.94

374.49

873.66 829.98 797.11 789.14 789.14 789.14 2463.88

8.79 7.13 0.00 0.00 0.00 0.00 1094.26

882.45 837.10 797.11 789.14 789.14 789.14 3558.14

45.34 40.00 7.97 0.00 0.00 2372.09

821.29

364.75

1186.05

373.08

804.87 764.63 734.35 727.00 727.00 727.00 2253.30

8.10 6.57 0.00 0.00 0.00 0.00 1092.18

812.96 771.19 734.35 727.00 727.00 727.00 3345.48

41.77 36.85 7.34 0.00 0.00 2230.32

751.10

364.06

1115.16

371.68

736.08 699.27 671.58 664.87 664.87 664.87 2042.71

7.40 6.01 0.00 0.00 0.00 0.00 1090.10

743.48 705.28 671.58 664.87 664.87 664.87 3132.81

38.20 33.70 6.72 0.00 0.00 2088.54

680.90

363.37

1044.27

370.27

667.29 633.92 608.82

6.71 5.44 0.00

674.00 639.37 608.82

34.63 30.55 6.09

4.5

3 4 5 6 7 8 1 2

5

3 4 5 6 7 8 1 2

5.5

3 4 5 6 7 8 1 2

6

3 4 5 6 7 8 1 2

6.5

3 4 5 6 7 8 1 2

7

3 4 5 6 7 8 1 2

7.5

3 4 5 6 7 8 1 2 3 4 5

After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input After primary energy transformation After boiler After storage After distribution After heating system After room After envelope Input After primary energy transformation After boiler After storage After distribution

Storage Distribution Heating Room air Envelope Primary energy transform Generation Storage Distribution Heating Room air Envelope Primary energy transform Generation Storage Distribution Heating Room air Envelope Primary energy transform Generation Storage Distribution Heating Room air Envelope Primary energy transform Generation Storage Distribution Heating Room air Envelope Primary energy transform Generation Storage Distribution Heating Room air Envelope Primary energy transform Generation Storage Distribution Heating

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Table 8 (continued ) Temperature (1C)

nn

Number of part**(  )

Flow parts

Heat energy rate Electrical energy (W) rate (W)

6 7 8

After heating system After room After envelope

602.73 602.73 602.73

0.00 0.00 0.00

Total energy rate Energy loss (or gain) (W) rate (W) 602.73 602.73 602.73

0.00 0.00

Part explanation

Room air Envelope

Number of part is connected with Sankey/Grassmann diagram.

Table 9 Exergy analysis results of the electrical energy option based building heating. Temperature (1C)

Number of part**(  )

Flow parts

4

1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

Input After primary energy After boiler After storage After distribution After heating system After room After envelope Input After primary energy After boiler After storage After distribution After heating system After room After envelope Input After primary energy After boiler After storage After distribution After heating system After room After envelope Input After primary energy After boiler After storage After distribution After heating system After room After envelope Input After primary energy After boiler After storage After distribution After heating system After room After envelope Input After primary energy After boiler After storage After distribution After heating system After room After envelope Input After primary energy After boiler After storage After distribution After heating system After room After envelope Input After primary energy After boiler After storage After distribution After heating system After room After envelope

4.5

5

5.5

6

6.5

7

7.5

nn

transformation

transformation

transformation

transformation

transformation

transformation

transformation

transformation

Number of part is connected with Sankey/Grassmann diagram.

Total exergy rate (W)

Exergy loss (or gain) rate (W)

Part explanation

4621.47 1528.91 198.16 189.54 176.14 78.42 59.97 0.00 4408.80 1458.71 182.90 174.88 162.35 72.10 54.72 0.00 4196.14 1388.52 168.08 160.65 148.98 65.99 49.68 0.00 3983.47 1318.32 153.69 146.84 136.02 60.08 44.86 0.00 3770.81 1248.13 139.72 133.45 123.47 54.38 40.24 0.00 3558.14 1177.93 126.19 120.48 111.33 48.88 35.84 0.00 3345.48 1107.74 113.10 107.93 99.61 43.59 31.64 0.00 3132.81 1037.54 100.43 95.80 88.30 38.52 27.66 0.00

3092.56 1330.75 8.62 13.40 97.71 18.45 59.97

Primary energy transform Generation Storage Distribution Heating Room air Envelope

2950.09 1275.81 8.02 12.53 90.25 17.38 54.72

Primary energy transform Generation Storage Distribution Heating Room air Envelope

2807.62 1220.44 7.43 11.67 82.99 16.30 49.68

Primary energy transform Generation Storage Distribution Heating Room air Envelope

2665.15 1164.64 6.85 10.82 75.94 15.22 44.86

Primary energy transform Generation Storage Distribution Heating Room air Envelope

2522.68 1108.41 6.28 9.98 69.09 14.13 40.24

Primary energy transform Generation Storage Distribution Heating Room air Envelope

2380.21 1051.74 5.72 9.14 62.45 13.04 35.84

Primary energy transform Generation Storage Distribution Heating Room air Envelope

2237.74 994.64 5.17 8.32 56.02 11.95 31.64

Primary energy transform Generation Storage Distribution Heating Room air Envelope

2095.27 937.11 4.63 7.50 49.78 10.85 27.66

Primary energy transform Generation Storage Distribution Heating Room air Envelope

H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C reference temperatures, respectively. The exergy analysis results of the solar energy option based building heating are tabulated in Table 7. The total exergy (input) rates of the solar energy supported system are computed to be 1104.62 W, 1102.54 W, 1100.47 W, 1098.39 W, 1096.31 W, 1094.23 W, 1092.15 W, and 1090.08 W for the dead state temperatures of 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C, respectively. Also, the maximum heat loss of this system is calculated for the generation part with the value of 535.95 W, 528.60 W, 520.83 W, 512.62 W, 503.98 W, 494.90 W, 485.40 W, and 475.46 W for the dead state temperatures of 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C, respectively. The energy analysis results of the natural gas fired electrical energy option based (electrical boiler) building heating are listed in Table 8. The total energy (input) rates of the electrical energy supported system are calculated as 4621.47 W, 4408.80 W, 4196.14 W, 3983.47 W, 3770.81 W, 3558.14 W, 3345.48 W, and 3132.81 W for the 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C reference temperatures, respectively. Also, the maximum energy loss is found for the primary energy transform part. The rates of the primary energy transform are determined to be 3080.98 W, 2939.20 W, 2797.42 W, 2655.65 W, 2513.87 W, 2372.09 W, 2230.32 W, and 2088.54 W for the 4 1C, 4.5 1C, 5 1C,

1029

5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C reference temperatures, respectively. The exergy analysis results of the electrical energy option based building heating are shown in Table 9. The total exergy (input) rates are determined to be 4621.47 W, 4408.80 W, 4196.14 W, 3983.47 W, 3770.81 W, 3558.14 W, 3345.48 W, and 3132.81 W for the dead state temperatures of 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C, respectively. The most of the total exergy is lost in the generation part of this system. The values of the generation losses are found as 3092.56 W, 2950.09 W, 2807.62 W, 2665.15 W, 2522.68 W, 2380.21 W, 2237.74 W, and 2095.27 W for the dead state temperatures of 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C, respectively. The general Sankey and Grassmann diagrams of the energy option based building heating are illustrated in Figs. 2 and 3, respectively. These diagrams show the loss and flow of the process including parts in which energy or exergy is lost. The numbers in the Sankey and Grassmann diagrams (1–8) are related with the “number of part” in Tables 1–9. The results of each of Tables 1–9 can be used associated with Sankey and Grassmann diagrams. The energy and exergy efficiencies results of the biomass, solar and electrical energy options based building heating are tabulated in Table 10, while the variations of the energetic and exergetic efficiencies are shown in Fig. 4. The maximum energy and exergy

Fig. 2. General Sankey diagram of the energy option based building heating.

Fig. 3. General Grassmann diagram of the energy option based building heating.

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H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

Solar

Electrical

4 4.5 5 5.5 6 6.5 7 7.5 4 4.5 5 5.5 6 6.5 7 7.5 4 4.5 5 5.5 6 6.5 7 7.5

Energy efficiency ηbuild (%)

ηbuild;overall (%)

77.01 73.10 69.12 65.06 60.92 56.69 52.38 47.98 93.94 88.48 83.00 77.50 71.98 66.44 60.88 55.29 22.45 22.13 21.77 21.37 20.93 20.43 19.87 19.24

35.32 34.47 33.56 32.57 31.50 30.33 29.05 27.64 37.79 36.88 35.89 34.82 33.66 32.40 31.02 29.50 22.45 22.13 21.77 21.37 20.93 20.43 19.87 19.24

Exergy efficiency Ψ build (%)

4.48 4.13 3.78 3.45 3.12 2.81 2.50 2.21 5.43 4.96 4.51 4.08 3.67 3.28 2.90 2.54 1.30 1.24 1.18 1.13 1.07 1.01 0.95 0.88

efficiencies are found for solar collector, while the biomass energy option is the second efficient one. The electrical boiler has minimum energy and exergy efficiencies among the energy options. All of the energy options have maximum energy and exergy efficiencies at 4 1C reference (dead state) temperature, while the corresponding minimum rates are fount at 7.5 1C dead state temperature. The maximum overall energy efficiencies of the biomass, solar, and electrical energy option based building heating are determined to be 35.32%, 37.79%, and 22.45%, respectively. The maximum energy efficiencies ðηbuild Þ of the biomass, solar, and electrical energy option based building heating are determined to be 77.01%, 93.94%, and 22.45%, respectively, while the maximum overall energy efficiencies ðηbuild;overall Þ are determined to be 35.32%, 37.79%, and 22.45%, respectively. On the other hand, the maximum exergy efficiencies ðΨ build Þ of the biomass, solar, and electrical energy option based building heating are computed as 4.48%, 5.43%, and 1.30%, respectively. The sustainability analysis results of the biomass, solar and electrical energy options based building heating are given in Table 11, while the variations of the sustainability indexes are illustrated in Fig. 5. The solar and biomass energy options are more sustainable than the electrical energy option for the building heating. The most sustainable energy option is solar energy with a rate of 1.0574, while the minimum sustainable energy option is electrical energy with a rate of 0.0089. Also, all of the energy options have maximum and minimum sustainability index rate at 4 1C and 7.5 1C reference state temperature, respectively. The environmental analysis results of the biomass, solar and electrical energy options based building heating are tabulated in Table 12, while the variations of the environmental analysis results are shown in Fig. 6. The solar energy is the most environmental energy option, after that the biomass is the second best environmental energy option. Also, the natural gas fired electrical energy is the worst environmental energy option among the options. The worst environmental results are found at 4 1C reference temperature as 0.6082 kg-CO2/day, 0.1599 kg-CO2/day, and 29.614 kg-CO2/day for the biomass, solar, and electrical energy options, respectively.

100 90 80 70 60 50 40 30 20 10 0

Biomass Solar Electrical

4

4.5

5

5.5

6

6.5

7

7.5

Reference temperature (°C) 40 Overall energy efficiency (%)

Biomass

Reference temperature T (1C)

35 30 25 20 15

Biomass

10

Solar

5 0

Electrical

4

4.5

5

5.5

6

6.5

7

7.5

Reference temperature (°C) 6 Exergy efficiency (%)

Energy option

Energy efficiency (%)

Table 10 Energy and exergy efficiencies results of the biomass, solar and electrical energy options based building heating.

Biomass Solar Electrical

5 4 3 2 1 0

4

4.5

5

5.5

6

6.5

7

7.5

Dead state temperature (°C) Fig. 4. Variations of the energetic and exergetic efficiencies. (a) Energy efficiency (build ) of the energy options, (b) Overall energy efficiency (build ,overall) of the energy options and (c) Exergy efficiency (build) of the energy options.

Table 11 Sustainability analysis results of the biomass, solar and electrical energy options based building heating. Reference temperature (1C)

4 4.5 5 5.5 6 6.5 7 7.5

Energy options Biomass

Solar

Electrical

1.0469 1.0430 1.0393 1.0357 1.0322 1.0289 1.0257 1.0226

1.0574 1.0522 1.0473 1.0426 1.0381 1.0339 1.0298 1.0260

1.0131 1.0126 1.0120 1.0114 1.0108 1.0102 1.0095 1.0089

The exergoenvironmental analysis results of the biomass, solar and electrical energy options based building heating are given in Table 13, while the variations of the exergoenvironmental analysis results are illustrated in Fig. 7. The most exergoenvironmental

H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

1.06

The biomass, solar, and electrical energy options based building heating are investigated and compared along with energy, exergy, sustainability, environmental, exergoenvironmental, enviroeconomic and exergoenviroeconomic analyses. The building floor area is 120 m2. Also, the reference (dead state) temperatures are considered as 4 1C, 4.5 1C, 5 1C, 5.5 1C, 6 1C, 6.5 1C, 7 1C, and 7.5 1C. The concluded remarks of this study may be explained as follows: (i) The energy and exergy efficiencies of all of the energy options are inversely proportional with the reference temperature. The most efficient energy option is found to be solar energy, while biomass energy is the second one. On the other hand, electrical energy is the inefficient energy option among the options. So, the renewable energy options such as solar and biomass are the most efficient ones comparing the natural gas fired electrical energy option. Also, the maximum exergy efficiencies of the biomass (4.48%) and solar (5.43%) energy options are close to each others. The situation is same for their energetic efficiencies too. The maximum overall energy

Biomass

1.05

0.7

Solar

1.04

Electrical

1.03 1.02 1.01 1.00 0.99 0.98

4

4.5

5

5.5

6

6.5

7

7.5

Environmental parameter (Biomass&Solar) (kg-CO2/day)

Sustainability index (-)

5. Conclusions

Biomass Solar Electrical

0.6

35 30

0.5

25

0.4

20

0.3

15

0.2

10

0.1

5

0

Reference temperature (°C)

4

4.5

5

5.5

6

6.5

7

7.5

Environmental parameter (Electrical) (kg-CO2/day)

energy option is found to be solar energy for the building heating, while the natural gas fired electrical energy option is not exergoenvironmental as much as biomass and solar energy options. The exergoenvironmental result values of the all energy options are maximum at 4 1C reference temperature. The worst exergoenvironmental results are found as 0.2771 kg-CO2/day, 0.0643 kg-CO2/day, and 29.614 kg-CO2/day for the biomass, solar and electrical energy options, respectively at that temperature. The enviroeconomic and exergoenviroeconomic analyses results of the biomass, solar and electrical energy options based building heating are shown in Table 14, while the variations of the enviroeconomic analysis results, and the variations of the exergoenviroeconomic analysis results are given in Figs. 8 and 9, respectively. The maximum enviroeconomic results are found as 0.0088 $/day, 0.0023 $/day, and 0.4294 $/day for the biomass, solar, and electrical energy options at 4 1C reference temperature, respectively. On the other hand, the maximum exergoenviroeconomic analysis results are determined to be 0.0040 $/day, 0.000933 $/day, and 0.4294 $/day for the biomass, solar, and electrical energy options at 4 1C reference temperature, respectively.

1031

0

Reference temperature (°C)

Fig. 5. Variations of the sustainability indexes.

Fig. 6. Variations of the environmental analysis results.

Table 12 Environmental analysis results of the biomass, solar and electrical energy options based building heating. Energy option

Temperature (1C)

Required primary energy input rate (kW)

Renewable energy input rate (kW)

Total of required primary energy and renewable energy input rates (kW)

CO2 emission value for the energy option (kg-CO2/kW h)

Working hours of the system (h/day)

CO2 emission releasing in a day (kg-CO2/day)

Biomass

4 4.5 5 5.5 6 6.5 7 7.5 4 4.5 5 5.5 6 6.5 7 7.5 4 4.5 5 5.5 6 6.5 7 7.5

1.348 1.335 1.321 1.308 1.295 1.282 1.269 1.256 1.105 1.103 1.100 1.098 1.096 1.094 1.092 1.090 4.621 4.409 4.196 3.983 3.771 3.558 3.345 3.133

1.591 1.495 1.400 1.305 1.210 1.114 1.019 0.924 1.641 1.543 1.445 1.346 1.248 1.150 1.052 0.953 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

2.938 2.830 2.722 2.613 2.505 2.397 2.289 2.180 2.746 2.645 2.545 2.445 2.344 2.244 2.144 2.043 4.621 4.409 4.196 3.983 3.771 3.558 3.345 3.133

0.023 0.023 0.023 0.023 0.023 0.023 0.023 0.023 0.00647 0.00647 0.00647 0.00647 0.00647 0.00647 0.00647 0.00647 0.712 0.712 0.712 0.712 0.712 0.712 0.712 0.712

9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9

0.6082 0.5858 0.5634 0.5410 0.5186 0.4961 0.4737 0.4513 0.1599 0.1540 0.1482 0.1424 0.1365 0.1307 0.1248 0.1190 29.614 28.252 26.889 25.526 24.163 22.801 21.438 20.075

Solar

Electrical

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H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

Table 13 Exergoenvironmental analysis results of the biomass, solar and electrical energy options based building heating. Temperature (1C)

Total exergy input rate (kW)

CO2 emission value for the energy option (kg-CO2/kW h)

Working hours of the system (h/day)

CO2 emission releasing in a day (kg-CO2/day)

Biomass

4 4.5 5 5.5 6 6.5 7 7.5 4 4.5 5 5.5 6 6.5 7 7.5 4 4.5 5 5.5 6 6.5 7 7.5

1.339 1.326 1.314 1.301 1.289 1.276 1.264 1.251 1.105 1.103 1.100 1.098 1.096 1.094 1.092 1.090 4.621 4.409 4.196 3.983 3.771 3.558 3.345 3.133

0.023 0.023 0.023 0.023 0.023 0.023 0.023 0.023 0.00647 0.00647 0.00647 0.00647 0.00647 0.00647 0.00647 0.00647 0.712 0.712 0.712 0.712 0.712 0.712 0.712 0.712

9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9

0.2771 0.2745 0.2719 0.2693 0.2668 0.2642 0.2616 0.2590 0.0643 0.0642 0.0641 0.0640 0.0638 0.0637 0.0636 0.0635 29.614 28.252 26.889 25.526 24.163 22.801 21.438 20.075

Solar

Electrical

35

25 0.20

20

0.15

15

Biomass Solar Electrical

0.10 0.05

10 5

4

4.5

5

5.5

6

6.5

7

7.5

Enviroeconomic parameter (Biomass&Solar) ($/day)

30

0.25

0.010

Exergoenvironmental parameter (Electrical) (kg-CO2/day)

Exergoenvironmental parameter (Biomass&Solar) (kg-CO2/day)

0.30

0.008 0.007

0.50 0.45 0.40 0.35

0.006

0.30

0.005

0.25

0.004

0.20

0.003

0.15

0.002

0.10

0.001

0.05

0.000

0

Biomass Solar Electrical

0.009

4

4.5

5

5.5

6

6.5

7

7.5

Enviroeconomic parameter (Electrical) ($/day)

Energy option

0.00

Reference temperature (°C)

Reference temperature (°C) Fig. 8. Variations of the enviroeconomic analysis results. Fig. 7. Variations of the exergoenvironmental analysis results.

Biomass

0.0040

Solar

0.50

Electrical

0.45 0.40

0.0035

0.35

0.0030

0.30

0.0025

0.25

0.0020

0.20

0.0015

0.15

0.0010

0.10

0.0005 0.0000

0.05

4

4.5

5

5.5

6

6.5

7

7.5

Exergoenviroeconomic parameter (Electrical) ($/day)

0.0045 Exergoenviroeconomic parameter (Biomass&Solar) ($/day)

efficiencies of the biomass and solar energy options are found as 35.32% and 37.79%, respectively. Hence, these two energy options can be used efficiently for the building heating comparing to electrical energy option. (ii) The most sustainable energy options are determined for solar and biomass energies. Sustainability indexes of the energy options are inversely proportional with reference temperature. The index results are maximum at the lowest reference temperature of 4 1C. If the reference temperature increases the sustainability of the biomass, solar and electrical energy options based building heating decreases. (iii) The most environmental energy option is found for renewable energy options. The result values are inversely proportional with reference (environment) temperature. The most environmental energy option is solar energy. According to environmental analysis, maximum 0.1599 kg-CO2 is released in a day for the solar energy option, while this value is 0.6082 kg-CO2 for biomass energy, and 29.614 kg-CO2 for natural gas fired electrical energy. The maximum CO2 releasing in a day is found for the lowest reference temperature of 4 1C which means the system is worst environmental at this reference temperature.

0.00

Reference temperature (°C)

Fig. 9. Variations of the exergoenviroeconomic analysis results.

The best environmental results are found at 7.5 1C reference temperature. So, utilization of renewable energy options can result with better environmental protection. (iv) Among the energy options, solar and biomass energies have the best exergoenvironmental results in which exergetic results are taken into account. These result values are also

H. Caliskan / Renewable and Sustainable Energy Reviews 43 (2015) 1016–1034

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Table 14 Enviroeconomic and exergoenviroeconomic analyses results of the biomass, solar and electrical energy options based building heating. Temperature (1C)

CO2 emission price ($/kgCO2)

Biomass

Solar

Electrical

Enviroeconomic CO2 emission parameter ($/day) releasing in a day (kg-CO2/day)

CO2 emission Enviroeconomic parameter ($/day) releasing in a day (kg-CO2/day)

CO2 emission Enviroeconomic parameter ($/day) releasing in a day (kg-CO2/day)

0.1599 0.1540 0.1482 0.1424 0.1365 0.1307 0.1248 0.1190

29.6144 28.2516 26.8888 25.5261 24.1633 22.8006 21.4378 20.0750

4 4.5 5 5.5 6 6.5 7 7.5

0.0145 0.0145 0.0145 0.0145 0.0145 0.0145 0.0145 0.0145

0.6082 0.5858 0.5634 0.5410 0.5186 0.4961 0.4737 0.4513

0.0088 0.0085 0.0082 0.0078 0.0075 0.0072 0.0069 0.0065

Temperature (1C)

CO2 emission price ($/kgCO2)

Exergoenviroeconomic CO2 emission parameter ($/day) releasing in a day (kg-CO2/day)

CO2 emission Exergoenviroeconomic parameter ($/day) releasing in a day (kg-CO2/day)

CO2 emission Exergoenviroeconomic parameter ($/day) releasing in a day (kg-CO2/day)

4 4.5 5 5.5 6 6.5 7 7.5

0.0145 0.0145 0.0145 0.0145 0.0145 0.0145 0.0145 0.0145

0.2771 0.2745 0.2719 0.2693 0.2668 0.2642 0.2616 0.2590

0.0643 0.0642 0.0641 0.0640 0.0638 0.0637 0.0636 0.0635

29.6144 28.2516 26.8888 25.5261 24.1633 22.8006 21.4378 20.0750

0.0040 0.0040 0.0039 0.0039 0.0039 0.0038 0.0038 0.0038

inversely proportional with reference temperature. The maximum rates of CO2 releasing in a day are found at 4 1C reference temperature (at which the system is not exergoenvironmental as much as at 7.5 1C) as 0.2771 kg-CO2, 0.0643 kg-CO2, and 29.614 kg-CO2 for the biomass, solar and electrical energy options, respectively. (v) The enviroeconomic and exergoenviroeconomic results of the biomass, solar and electrical energy option based building heating are inversely proportional with reference temperature. The maximum released CO2 prices in a day are determined to be 0.0088 $, 0.0023 $, and 0.4294 $ for the biomass, solar and electrical energy options, respectively, while the corresponding exergoenviroeconomic results are found as 0.0040 $, 0.000933 $, and 0.4294 $ for the biomass, solar, and electrical energy options, respectively at 4 1C reference temperature. So, the biomass and solar energies cause less CO2 pricing than the electrical energy.

In this study, the best energetic, exergetic, environmental and sustainable results are found for the solar energy option for the building heating. So, it can be recommended that the utilization of solar energy systems for building heating applications should be encouraged. Also, the natural gas fired electrical energy option and biomass energy option should be improved for building heating purposes (i.e. minimizations of energy cost and production process). As is seen from the detailed analyses based on the advanced thermodynamics, environmental and economic parameters, this study is expected to be beneficial to researchers, scientist, engineers and technologists working in the area of heating options for buildings. Also, the integrity of the analyses is proved three times using biomass, solar and electrical energy options for building heating. The analyses are not limited just for this three energy options. So, for a future work, these analyses can be applied for various energy options based building heating applications.

0.0023 0.0022 0.0021 0.0021 0.0020 0.0019 0.0018 0.0017

0.000933 0.000931 0.000929 0.000927 0.000926 0.000924 0.000922 0.000920

0.4294 0.4096 0.3899 0.3701 0.3504 0.3306 0.3108 0.2911

0.4294 0.4096 0.3899 0.3701 0.3504 0.3306 0.3108 0.2911

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