Evaluation of Domestic Solar Water Heating System in Jordan

7/29/2019 Evaluation of Domestic Solar Water Heating System in Jordan

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Energy Conrrrs. M gntt Vol. 38. No. 18, pp. 1 8l~l822. 1997( 1997Elsevier Science Ltd. All riehts reservedPergamonPII: s01%-8904(96)00115-x Printed in &at Britain0196-8904197 $17.00 + 0.00

EVALUATION OF DOMESTIC SOLAR WATER HEATINGSYSTEM IN JORDAN USING ANALYTIC HIERARCHYPROCESS

MOUSA S. MOHSEN and BILAL A. AKASHDepartment of Mechanical & Industrial Engineering, Applied Science University, Amm an, 119 31 Jordan

(Received 12 Fehrunry 1996)

Abstract-In addition to the solar water heating (SW H) system, other domestic water heating systemsused in Jordan were considered in terms of benefits nd costs using the Analytic Hierarchy Process. Interms of cost, the SW H system was the least expensive. On a percentage basis, the SW H cost about 13%compared to the most expensive heating system, LP G, of about 2 8% . In terms of benefits, the SWH w asalso the most beneficial. Approximately, the SWH benefits were about 31% , while the least benefits wereobtained from the kerosene water heating system, which is about 9%. By considering both cost and benefit(i.e. cost-to-benefit ratio), solar was also the least expensive, about 7%, with kerosene being the mostexpensive, over 30%. 6 199 7 Elsevier Science Ltd.Water heating Solar water heating systems Analytic hierarchy process

1. INTRODUCTIONDomestic solar water heating systems are widely used in Jordan. About 12% of dwellings in Jordanuse solar systems for water h eating. The financial evaluation of solar water heating systems incomparison with other types of conventional water heating systems is usually based on the priceof the fuel [l]. The financial evaluation of solar water h eating systems is conducted using one ofthe most known conventional methods, such as Net Present Value (NPV ) or Internal Rate ofReturn (IRR). The socio-economic evaluation make s assessm ents to all gains (benefits) and alllosses (costs) of solar water h eating systems which include the financial, social, cultural andecological impacts [2]. The most w idely used method in socio-economic analysis is the cost-benefitanalysis [3]. Although the assessme nt of socio-economic benefits and costs depends first of all onthe data p rovided by the cash flow sheets, it is supplemented by socio-economic impacts from thefield of welfare economics.In a review of existing surveys on financial evaluation methods and cost-benefit analysis for solarwater hea ting systems, a few limitations were observed:1. The problem of calculating revenues.2. The determination of interest r ate for discou nting.3. The problem of cost calculations for solar water heating systems.4. Estim ation of lifetime of solar water h eating components or of the system itself.The Analytic Hierarchy Process (AHP) can be used as a practical approach for addressing thesecost-benefit-benefit application issues.

2. THE ANALYTIC HIERARCHY PROCESS (AHP)The AHP has been effective in structuring many types of complex multi-criterion problems. For

example, the AHP has been applied to business decisions [4], choosing areas of R & D programs[5], the estima te of the economys impa ct on sales, the problem of traffic congestion, real estateinvestment [6], and w ater policies [7]. The AHP enables d ecision m akers to structure a problem

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1816 MOHSEN and AKASH: EVALUATION OF SWH SYSTEM IN JORDON

Benefits

SocialBenefits9

pq pi?--1 RJ p?iiq i]Fig. I. Benefits hierarchy diagram.

in the form of a hierarchy of preferences through a series of pairwise com parisons of relevantfactors or criteria.

There are five basic steps in applying the AHP in practice [6]:1. Structuring the decision hierarchy.2. Collecting data by pairwise com parisons.3. Checking consistency of material judgm ents.4. Applying the eigenvector method to compute weights.5. Aggrega ting the weights to determine a ranking of decision alternatives.

Applying the AHP app roach to cost-to-benefit analysis requires separating costs from benefitsand constructing separate hierarchies for benefits and costs. The benefits hierarchy assigns decision

costs

Optimum WaterHeating System

Fig. 2. Costs hierarchy diagram.


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MOHSEN and AKASH: EVALUATION OF SWH SYSTEM IN JORDON 1817

2 3 5

EqualImportance

Moderate Essential VeryImportance or Strong Strong

Importance ImportanceFig. 3. The pairwise comparison scale (after Saaty [6])

ExtremeImportance

Table 1. Relational scoring and relative weights of water heating systems with respect to benefits(a) Efficiency:cost offuelSolar water heatingElectric heatingCentral heatingKerosene heaterLPG heater

Solar water Electric Central Kerosene LPG Relativeheating heating heating heater heater weights

1 117 l/5 112 l/6 0.0447

I;33 5 2 0.415

5 I 3 l/3 0.1642 l/5 l/3 I l/5 0.0716 112 3 5 I 0.306

(b) Reliability:HardwarecostSolar water heatingElectric heatingCentral heatingKerosene heaterLPG heater(c) Availability of fuel:Maintenance &serviceSolar water heatingElectric heatingCentral heatingKerosene heaterLPG heater

Solar waterheating

I4735

Solar waterheating1

I /4Ii6I16I 6

Electricheating

114I4

1133

Electricheating4I

lj2I;2II2

Centralheating

117114I115113

Centralheating621II

Keroseneheater

1,335I4

Keroseneheater62III

LPG Relativeheater weights

115 0.044l/3 0.1483 0.467

l/4 0.0841 0.256

LPG Relativeheater weights6 0.5642 0.1691 0.089I 0.0891 0.089

(d) National economy:Auxiliarysystem

Solar waterheating

Electricheating

Centralheating

Keroseneheater

LPGheater

Relativeweights

Solar water heatingElectric heatingCentral heatingKerosene heaterLPG heater

I 9 9 Y 9 0.692l/9 I I I I 0.077119 I I I I 0.077I!9 1 I I I 0.077Ii9 I I I I 0.077

(e) Social benefits:Environmentalconstraints

Solar waterheating

Electricheating

Centralheating

Keroseneheater

LPGheater

Relativeweights

Solar water heatingElectric heatingCentral heatingKerosene heaterLPG heater

I 5 4 3 4 0.436I:5 I l/2 13 I.2 0.071l/4 2 I I 2 I 0.121I ,I 3 2 I 4 0.264I:4 2 I 14 I 0.108

07Safetv:EnvironmentalconstraintsSolar water heatingElectric heatingCentral heatingKerosene heater

Solar water Electric Central Kerosene LPG Relativeheating heating heating heater heater weightsI 5 4 7 3 0.436

l/5 I I 12 1-3 I,2 0.07 II 4 2 I 12 I 0.12112 3 2 I 4 0.264

LPG heater I /4 2 I 14 I 0.108


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1818 MOHSEN and AKASH: EVALUATION OF SWH SYSTEM IN JORDON

criteria. The category weight is used to adjus t the overall w eight of each benefit criterion. Afteralternatives are evaluated with respect to all benefit and cost criteria, an overall benefit weight anda cost weight are determ ined for each alternative. Benefit cost ratios are formed to facilitate thefinal selection of alternatives. Usin g this approach to cost-to-benefit analys is can improve this typeof decision-making tool by employing the pairwise comparison scale to quantify non-financialfactors.The primary advantage of the basic AHP approach is its simplicity; once the criteria are agreedupon, and supporting data are collected for each alternative, the AHP analysis can be processed.Sensitivity a nalysis can be used to test the solution, and exam ine how changes in criterion weightswould alter the weights and rankings of the individual alternatives.

3. FORMULATIONThe decision regarding the selection of an optimum water heating system in Jordan was evaluated

according to its benefits and costs. The benefit and cost hierarchies were considered separately, andcost-to-benefit ratios were obtained. The benefit and cost hierarchies were constructed as shownin Figs 1 and 2, respectively. The ov erall objective for both hierarchies was to select an optimumwater heating system. As shown in Fig. 1, the benefits hierarchy includes all possible benefits thatmay be derived from v arious water heating system s. The benefit criteria at level 2 are efficiency,reliability, availability of fuel, nationa l economy, social benefits, and safety.

Thus, the measurem ent of potential benefits from a particular water heating system exceeds, inscope, the financial return on that system and encom passes its contribution to the overall benefitof the nation. These socio-economic gains are represented by the criteria of the national economyand social benefits.

Figure 2 shows the cost hierarchy. The cost criteria at level 2 are cost of fuel, hardware cost,maintenance and service, auxiliary system, and environmental constraints. All items in the costcriteria can be related in terms of cost or money-value, apar t from one item which is very difficultto quantify in terms of money, namely, environmental constraints, which measures the effect ofa water hea ting system on the environm ent, directly or indirectly. The third level of the benefit andcost hierarchies represents the most common systems used for heating w ater in Jordan. Theselections of these alternatives were based on the results of an energy consump tion surveyconducted by the Ministry of Energy [l]. These alternative s are solar energy, electric, centralheating, kerosene fuel, and LPG water heating systems.

In order to establish the priorities (weights) of the alternatives in both the benefit and costhierarchies, pairwise comparisons were necessary i.e. to compare the alternatives in pairs againsta given criterion. Figure 3 shows the scale developed by Saaty [6] for a pairwise co mparison. Itdefines values l-9 assigned to judgmen ts in comparing pairs of level 3 against a criterion in thesecond level of both the benefit and cost hierarchies. Table 1 shows the relational scoring a ndrelative w eights for the different w ater heating systems considered with respect to the benefits. Therelative w eight of each benefit criterion is obtained for all heating system s. Table 2 represents therelational scoring for all benefit criteria with respect to each other, as well as the relative w eightscorings of each benefit criterion. This is the pairwise comparison matrix of the goal defined atlevel 1: the optimum water heating system. The last column gives the relative w eight of theirpriorities, wh ich indicates that the reliability of the system is the most important, followed byavailability, efficiency, national economy , safety and social benefits. All five entries in the vector

Table 2. Relational scoring and relative weights for optimum benefits against each otherOptimum water Availability National Socialheating system Efficiency Reliability of fuel economy benefits SafetyEfficiency I l/3 l/2 1 3 2Reliability 3 1 2 4 5 3Availability of fuel 2 l/2 1 2 4 4National economy 1 l/4 l/2 1 2 2Social benefits l/3 115 l/4 l/2 1 l/2Safety l/2 l/3 l/4 l/2 2 1

Relativeweights0.1360.3650.2400.1200.0550.084


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1820 MOHSEN and AKASH: EVALUATION OF SWH SYSTEM IN JORDONTable 4. Relational scoring and relative weights of water heating systems with respect to cost(a) Cost of fuel:

cost offuel Solar waterheating Electricheating Centralheating Keroseneheater LP Gheater RelativeweightsSolar water heating 1 l/8 116 l/5 l/7 0.0 34Electric heating 8 I 3 5 3 0.452Central heating 6 1/3 I 2 l/3 0.153Kerosene heater 5 lj5 112 1 l/3 0.102LPG heater 7 l/3 3 3 I 0.259(b) Hardware cost:Hardwarecost Solar waterheating Electricheating Centralheating Keroseneheater LP Gheater RelativeweightsSolar water heatingElectric heatingCentral heatingKerosene heaterLPG heater(c) Maintenance and service:

1 2 3 5 l/2 0.243l/2 1 2 5 l/5 0.1501,3 112 1 2 I6 0.081l/5 l/5 112 1 117 0.0472 5 6 1 1 0.480

Maintenance &serviceSolar water heatingElectric heatingCentral heatingKerosene heaterLPG heater(d) Auxiliary system:

Solar water Electricheating heating1 l/22 18 65 53 4

Centralheatingl/8l/6123

Keroseneheaterl/5l/5l/2II2

LPG Relativeheater weightsl/3 0.054114 0.068l/3 0.2472 0.362I 0.268

AuxiliarysystemSolar water heatingElectric heatingCentral heatingKerosene heaterLPG heater

Solar waterheatingI

l/911 911 9l/9

Electric Central Kerosene LPG Relativeheating heating heater heater weights9 9 9 9 0.692I 1 I I 0.077I I 1 1 0.077I 1 1 1 0.077I I I I 0.077

(e) Environmental constraints:EnvironmentalconstraintsSolar water heatingElectric heatingCentral heatingKerosene heaterLPG heater

Solar waterheatingI4763

Electricheatingl/41652

Centralheating11 7l/6I11 2l/3

Keroseneheaterl/611 52I11 3

LPG Relativeheater weights113 0.044l/2 0.0913 0.4293 0.3051 0.131

of priorities obtained in each of the six matrices are weighted by the priority for that correspondingcriterion. An overall relative weight factor is then obtained from the results of Tables 1 and 2. Theseweights are of the overall relative prope rties of the five different water heating system s against thesix benefits criteria, as they are presen ted in Table 3.

Similarly, the same procedure was repeated for the cost hierarchy, where Table 4 show s thevector of priorities of the five different water heating system s with respect to each cost criterion.Table 5 shows the pairwise comp arison matrix of the cost criteria with respect to the goal defined

Table 5. Relational scorina and relative weights for optimum costsOptimum waterheating systemCost of fuelHardware costMaintenance costAuxiliary systemEnvironmentalconstraints

cost offuel Hardwarecost Maintenancecost Auxiliary Envirol Relativesystem constraints weights1 3 3 4 5 0.44011 3 1 I 3 4 0.205113 3 0.2051 4 113 I)3 1 1; 2 0.070115 l/4 l/4 2 1 0.082


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MOHSEN and AKASH: EVALUATION OF SWH SYSTEM IN JORDON 1821Table 6. Overall relative weights for optimum costs

Optimum water cost of Hardwa re Maintenance Auxiliary Environmental Relativeheating system fuel cost cost system constraints weightsSolar water (0.034)(0.440) + (0.243)(0.205) + (0.054)(0.205) + (0.692)(0.070) + (0.044)(0.082) = 0.128heatingElectric (0.452)(0.440) + (0.150)(0.205) + (0.068)(0.205) + (0.077)(0.070) + (0.091)(0.082) = 0.256heatingCentral (0.153)(0.440) + (0.081)(0.205) + (0.247)(0.205) + (0.077)(0.070) + (0.429)(0.082) = 0.175heatingKerosene (0.102)(0.440) + (0.047)(0.205) + (0.362)(0.205) + (0.077)(0.070) + (0.305)(0.082) = 0.159heaterLPG (0.259)(0.440) + (0.480)(0.205) + (0.268)(0.205) + (0.077)(0.070) + (0.131)(0.082) = 0.283heater

at level 1 of the cost hierarchy. Table 6 show s the overall prior ities for the different water heatingsystems with respect to the costs.

4. RESU LTS AND DISCUSSION

The benefit hierarchy results show that, ba sed on efficiency and reliability, the solar water heatingsystem wa s the least efficient and reliable (s ee Table 1). How ever, in terms of availability of fuel,national economy, social benefits and safety, the solar heating system was the most beneficialamong all other heating systems. Reliability and availability of fuel were the two highest factorsin determining the benefits factor. They have values of 36.5% and 24% , respectively, as shown inTable 2. In terms of overall benefits or returns, the solar water heating system wa s the mostbeneficial and had the highest returns.

The cost hierarchy show s that the solar water heating system w ould have the highest hardwarecost, and it has the highest need of an auxiliary system (see Table 4 ). However, in terms of costof fuel, maintenance and service, and environmental constraints, solar energy costs the least. Thecost hierarchy shows that, in any water heating system, the cost of fuel counts the most, about44%, as shown in Table 5. Hardware cost and maintenance cost follow with about 20% each.Table 6 show s that the solar heating system is the least expensive system (about 13%).

The overall cost priorities (weights) were divided by the overall benefit weights to obtaincost-to-benefit ratios. These ratios were also normalized to give new weights, as shown in Figure 4.The figure clearly show s that, even though the cost of the solar water heating system w as the least

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Solar Ekctric Central Kerosene LPGWater Heating System

Fig. 4. Com parison of benefits, costs, and cost-to-benefit ratios.


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I822 MOHSEN and AKASH: EVALUATION OF SWH SYSTEM IN JORDON

expensive (approximately 13%) based on the cost hierarchy, it is even lower (about 7%) b ased onboth the cost and benefit hierarchies. Other systems were affected. For ex ample, b ased on the costhierarchy, kerosene heaters come second (about 16%). However, based on the cost and benefithierarchies, it was the most expensive of all systems (i.e., the worst choice, approximately 30%).Kerosene was the most expensive becau se it had the lowest percentage of benefits.

5. CONCLUSIONSBased on the Analytic Hierarchy Process, the solar water heating system was the most

inexpensive type heater in domestic use. By considering cost-to-benefit hierarchies, the solar waterheating system w as still the most inexpensive, but with more convincing results. In conclusion, wecan say that the solar water heating system is the most desirable system to be used in Jordan.

REFERENCES1. Kabariti, M. and Taher, A., Proc. 4th Arab Int. Solar Energy Conf... Amman, Jordan, 1993, 1023.2. Gocht, W., Proc. 4th Arab Int. Solar Energy Conf., Amman, Jordan, 1993, 989.3. Mufti, A., Proc. 4th Arab Inf. Solar Energy Conf., Amman, Jordan, 1993, 1015.4. Liberatore, M. J., Monahan, T. F. and Stout, D. E., The Engineering Economist, 1992, 38, 31.5. Elkarmi, F., Proc. 4th Arab Int. Solar Energy Co@., Amman, Jordan, 1993, 1003.6. Saaty, T. L., The Analytic Hierarchy Process, McGraw-Hill International 1980.I. Al-Jayyousi, 0 . R. and Shatanawi, M. R., Water Resources Development, 1995, 11, 315.

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Evaluation of Domestic Solar Water Heating System in Jordan