Solar Energy Potential for Hot Water in the Hotel Sector in Libya Mohammad J.R. Abdunnabi,
Abdulghani M. Ramadan
Centre for Solar Energy Research and Studies, Tajoura, P.O. Box 12932, Tripoli - Libya, e-mail:
[email protected]
Faculty of Engineering, Al-Mergib University, Al-KhumsLibya, e-mail:
[email protected]
Abdulfatah A. Adweeb Higher Institute for general Professions, Gharian -Libya. e-mail:
[email protected] Abstract— Hotels are considered one of the most energy consumers in the building sector and are thus responsible for quite large amounts of carbon dioxide emissions. The major part of this energy is utilized for water heating, space heating and cooling, and lighting. This study aims to estimate the energy potential of hot water in the hotel sector of Libya, and the opportunities of saving an important part of this energy through utilizing solar energy. The study depends on distributing questionnaires to a big sample of hotels over different cities in Libya. The information that was gathered from the questioners with other information from different sources is analyzed and projected all over Libya. The outcome of this study is to estimate a theoretical and technical potential of using solar energy in providing hot water to the hotel sector of Libya. Results have shown that there is a high potential of hot water in the hotel sector of Libya with over 18.54 (GWh/year while the technical potential of using solar energy for heating water is 25,386 m2 of collector area. The savings in using solar energy technology for water heating in the hotels in Libya is 1.3 million (L.D/year). Keywords— Solar energy; hot water potential; hotel sector; questionnaire.
I. INTRODUCTION Hotels use significant amount of energy and the potential for energy saving is large. The significance increase in the size of hotels sector requires more environmentally friendly services. In a study conducted on southern European hotels for the assessment of potential energy conservation has revealed that there is a potential for 25-30 percent energy savings, especially in hotels with high annual energy consumption. Another more detailed European studies (XENIOS project) have estimated savings of 15-20 percent for heating, 5-30 percent for cooling, 40-70 percent for hot water and 7-60 percent for lighting [1] . Rajagopalan et al. [2] performed a study on energy performance of hotels in Singapore. A survey was made on 29 quality hotels to collect data related to energy consumption and other relevant information. It has found that, the average total
energy use intensity (EUI) in these hotels is 427 kWh/m2, which is lower than that recorded in Ottawa and Hong Kong. Another study on 29 hotels in Singapore reported that the energy use intensity is 468 kWh/m2 [3]. Many hotels in the world have already installed solar energy systems to supply hot water for their hotels. For instance, almost 20-25% of the hotels in Manali, India (over 449 hotels) have installed SWHs in capacities ranging from 1,000 to 12,000 liters per day. Till early 2010, around 3,000 m2 of SWH systems have been installed in this city. On an average, these SWH systems are able to provide 50% of the annual demand. Water heating energy costs is almost 40% of the total energy cost of a hotel [4]. Quirante and Valenzuela [5] conducted a study for sizing especially designed small-sized parabolic trough concentrators' solar field for heating and cooling of a hotel located in Almeria, Spain. The annual total thermal energy demand of the hotel is 1577.03 MWh with 238.7 MWh for space heating, 879.84 MWh for space cooling and 458.49 MWh for water heating. Considering the area available around the hotel, 32 collectors connected in series with 8 parallel rows. Each collector 8 m long and its aperture length is 1 m with a total reflector surface area of 2048 m2. With this collector field, 25% of the cooling demand in summer and 76% of heating demand in winter is covered. This paper presents the opportunities of using solar energy technology in providing hot water in the hotel sector of Libya. II.
HOTEL AND TOURISM SECTORS IN LIBYA
Libya is located in the southern coast of the Mediterranean with a sea front of about 1900 kilometer. The area of Libya is about 1,759,540 square kilometer of the north of Africa. Libya has sprawling borders with length of approximately 4434 km. This geographical site gives Libya very important position that can be invested in tourism industry development in addition to its moderate climate and clear skies. This location which is near to the tourist marketing areas in Western Europe has an
effective impact in reducing travel costs and positively influenced the increasing size of tourists.
Table I shows the absorptive capacity for each hotel according to the classification.
Libya is a country full of luxurious and simple hotels, most of them are in Tripoli and some overlook seas and others inside the cities which contain means of transport, commercial stores, government buildings, some are located in the south due to the existence of tourists who study the sprawling deserts. According to the statistics of the information center and tourism statistics of the General Board for Tourism and Traditional Industry (GBTTI), the total number of classified private and public hotels in Libya is approximately 305 hotels and they are classified as follows: five stars, four stars, three stars, two stars and some are not classified at all. Commercial buildings are responsible for consuming large amount of electricity, it is estimated that 13.08% of the total electricity consumed in Libya in 2010 [6]. In the summer season according to a report published by CADMUS, 4% of these were consumed in the Hotel buildings as shown in Fig. 1[7].
It can be seen that the total number of beds in all hotels under study is about 7667 beds; with average of 66 beds for each hotel. Hotels classified from three to four stars and the non-classified hotels achieved more than 81% of the total absorptive capacity of the hotels under study. * 3%
not classified 26%
***** 5%
** 11% * **
**** 27%
***
*** 28%
**** ***** not classified
Fig. 2. Percentage of hotels under study and their classifications
TABLE I.
ABSORPTIVE CAPACITY FOR EACH HOTEL ACCORDING TO THE CLASSIFICATION.
Classification 1 2 3 4 5 Non-classified Total
Total Number of Beds 149 778 1695 2129 1249 1667 7667
Bed Average 37.5 65 75.7 78 149.5 61.5 77
Fig. 1. Breakout of electricity consumption in the commercial sector of Libya
III.
DATA COLLECTION AND ANALYSIS
The data were collected using a questionnaire which is designed of twenty one questions covering all the necessary information. The questionnaire was distributed among a number of hotels in Libya around Tripoli, Sebha, Sirt, Benghazi, AL-Bieda, Sebrata, Zwara, Zawia and Gharian. 120 questionnaires were distributed and 101 of them have been collected, i.e. approximately 85%. In order to get more precise data, a personnel interview with the hotels' managers was conducted. A. Hotel Classification Hotels usually differ according to the quality of services that they provide to their customers and they are listed as per international standards from one star to seven. Based on the samples collected from the questionnaires, the distribution of hotels in terms of classification was as shown in Fig. 2. The collected results show that most of the hotels were of classification 3 and 4 and non-classified. B. Number of Beds The number of hotels does not actually represent the absorptive capacity. Therefore, the hotel sizes are important.
C. Sources of Water The importance of knowing the sources of water is characterized by recognizing the variety of sources and the water quality used in satisfying the hotel needs. It was found out that the sources of water used in hotel sector are from two sources: the municipality 85% and private wells 15%. D. Water Quality The quality of water is varied according to the sources. From the data of the questionnaire, it has been found that fresh water is used in more than 67% of the hotels. The rest of hotels use brackish water. E. Means of Getting Hot Water There are a number of methods used in provision of hot water in the hotel sector. However, the most commonly used in Libya are electric heaters, solar water heaters and boilers. Fig. 3 illustrates the percentage of using of these technologies in hotel sector in Libya as per the sample under study. F. Surface Roof Area of Hotels The available roof surface area of the hotel is very important to be used for installation of solar systems for water heating. Table II shows the available free area of hotels in the sample under consideration.
III gives the concluded information about water and electricity of the hotels considered in the study. Over 86 hotels were answered the question about the water consumption, however, most of them were not accurate and excluded from the analyses. The most accurate values were obtained from interviewing the hoteliers. Concerning the question of electricity consumption in the hotels, 79 questioners were found answered. Also, the accuracy of most answers was very low. The range of annual electricity consumption varies from 74 to 223 kWh/m2.
boilers, 13 solar water heaters, 1
electric heaters, 87
electric heaters
solar water heaters
boilers
Fig. 3. Sources of getting hot water in hotel sector. TABLE III.
G. Number of stories The number of stories in the hotels might slightly affect the installation of solar systems and its performance. The higher number of stories the more complicated solar systems required. Fig. 4 illustrates number of stories of the hotels under consideration. TABLE II.
ROOF SURFACE AREAS OF THE HOTELS UNDER CONSIDERATION.
Surface Area of Hotels, (m2) ≤ 150 150 ≤ A≤300 300 ≤ A≤500 500 Not specified
Number of Hotels
Percentage %
17 34 16 20 14
16.8% 33.7% 15.8% 19.8% 13.8%
It clear from Fig. 3 that over 65% of the hotels are less than eight stories. 18% of the hotels are equal or less than three floors which are very suitable for installing solar water heating systems. 1
2
3
4
5
14 10 1% 5%
6
7 26 1%
8 30 1%
11 5%
9 10 1 1% 2 9%
11
14
26
30
8 4%
4 16% 7 16% 6 12%
1 2 3 4 5 Non-classified
Electricity kWh/m2 74 223 178 200 165
Water m3/bed 49 64 82 170 46
In similar studies conducted in other countries, Santamouris et al. [8] studied energy consumption in 158 Hellenic hotels. The annual average total energy consumption in these hotels was measured as 273 kWh/m2. Deng and Burnett [9] studied the energy use performance in 16 quality hotels in Hong Kong in terms of energy use index. The average total energy use was stated as 564 kWh/m2. Deng [10] analyzed the annual electrical and water consumption recorded in 36 quality hotels in Hong Kong. It was noted that average total energy use, average electricity use and average water use were 542, 370 kWh/m2 and 4.93 m3/m2, respectively. Thirty-seven different sized hotels in Vietnam were studied for electricity and water consumption. In this survey, annual average electricity and water consumptions for four-star, three-star and two-star hotels measured as 141kWh/m2 and 4 m3/m2, 143 kWh/m2 and 5 m3/m2 and 101 kWh/m2 and 4 m3/m2, respectively [11]. In fact, the low consumption in the Libyan hotels (similar to Vietnam case) is not out of energy saving programs; it is attributed to the low capacity factor in the hotels compared to the well-known tourist country.
3 8%
9 9%
ANNUAL ELECTRICITY AND WATER CONSUMPTION IN HOTELS
5 12%
Fig. 4. The average number of stories in the hotels under study.
H. Water and Electric consumption The questionnaire has involved questions about the consumption of water and electricity. It looks that the information are not reliable as there is no good documentations in the most hotels especially with water. The electricity is better as there is a metering in all hotels, however, revealing the information is the main issue of the most hostlers. Table
I. Awareness of SWH system benefits There are many questions were asked to hoteliers by the questioner related to their knowledge and interest to solar water heating system in the hotel sector. Figure 5 shows the response of the hotelier to five questions. It can be deduced from Figure 5 that most of the hoteliers do not have a good idea about solar water heating systems however the majority believe that using solar energy is better than electricity. Figure 6 illustrates the interest of hoteliers to install solar water heaters in their hotels. Most of the hoteliers 76% are interested to install solar systems in the medium future within the coming few years. Only 13% of the hostelries are not interested in installing solar water heating systems in their hotels.
No of Hotels
100 80
Hotels that have the same degree of classifications are treated the same irrespective of their locations.
Yes No
The hot water load pattern is not considered, only the amount of hot water consumed is considered.
60 40
In the calculation of the energy, the temperature of the cold water supply is considered constant during the whole year as 19 °C.
20 0 EQ1
EQ2
EQ3
EQ4
EQ5
EQ1: Do you have an idea about SWH systems? EQ2: Do you think heating water by solar is better than electrcity? EQ3: Is the roof area accupied? EQ4: Is there any obsticals or shading in the roof? EQ5: Is it possible to utilize roof for installing SWH system?
Fig. 5. Fig 5. Response of hoteliers on some general information.
Most of the hoteliers (73%) who are interested in installing solar water heating system for their hotels are expected the system cost is less than 10,000 L.D as shown in Figure 7. only 3% of the sample are interested to have a system even if the prices is up to 30,000 L.D. not interested 13% Long future 11%
The energy consumed for water heating (Qt) is calculated using the following equation:
Q t mC p (To Ti )
(1)
Where: m: Quantity of hot water consumed (kg) Cp: Specific heat of the water (kJ/kg K) To : Temperature of the hot water (°C) Ti : Temperature of the cold water supply (°C) The detailed calculations of the potential of water heating in the hotels' rooms, laundries and restaurants is available in Ref [13]. The estimated total energy consumed for water heating in the hotel sector of Libya in the main three areas (guest room, restaurants, laundry) is as follows:
near future 35%
Total energy = 108636.33 + 40190.69 +
medium 41%
34017.8558 = 182,844.875 MJ/day Annual energy = 66,738,380 MJ/year
Fig. 6. Response of hotelier on their interest to install SWH systems.
%3 % 24
% 35
L.D5,000 less than L.D 10,000 - 5,000
% 38
L.D 20,000 - 10,000 L.D 30,000 - 20,000
Fig. 7. Response of hoteliers to purchase SWH system according to the cost.
IV.
RESULTS AND DISCUSSION
A. Hot Water Potential Estimation Based on the design criteria utilized in sizing of heating water systems in the hotel building as mentioned in Ref[12], and the information obtained from the questionnaires related to the hotel rooms, restaurants and laundries are utilized to estimate the size of the theoretical potential of hot water requirement in the hotel sector of Libya. The amount of energy needed to heat water for hotel purposes is estimated by considering the following assumptions:
= 18,538,439 kWh/year This value is relatively very small when compared to other countries considered as tourist destination. For instance in Dubai more than 750 hotels and most of them are huge buildings and classified over three star. There would be a huge potential of investment in the hotel buildings if the tourism sector of Libya flourished in the near future. The cost of electricity used for heating water in the hotel sector according to the subsidized electricity tariff (7 Libyan Cent/kWh) is about 1.3 Million Libyan Dinars annually. B. Potential of Solar Energy Systems To calculate the technical potential of using solar energy technology in providing the hotel sector of Libya with the required hot water, the following information from the questionnaire and the technical data of flat plate solar collectors are considered: The hotels that have more than 8 stores are considered technically unfeasible to install SWHs. From data collected, 17% of the hotels are over 8 stories. 13% of the considered hotels are unsuitable from point view of shadow, small roof area and other obstacles Considering the overlapping 4%, the total illegible hotels are 26%, thus the eligible hotels are 74%
The thermal conversion efficiency of flat plate collectors is taken 21% The solar fraction is considered 75%. The estimated technical potential of solar water heaters can be found using the following correlation: Q (2) Ac d (% of SF )(% of eligible hotels ) G t Where
Ac , Collector areas potential (m2). Qd , Total hot water energy demand (kWh/year). Gt , Solar radiation on collector area (kWh/m2/year). , Average conversion efficiency. 18,538,439 * 0 . 75 * 0 . 74 0 . 21 * 1930 25 , 386 m 2
systems to restore balance and stability of the global environment. The study has shown that the potential of hot water in the hotel sector of Libya is over 18.54 GWh/year according to the current situation of the hotel sector. The cost of electricity used for heating water in the hotel sector according to the subsidized electricity tariff (7 Libyan Cent/kWh) is about 1.3 Million Libyan Dinars annually. Over 70% of these costs can be easily saved using solar water heaters technology. The estimated technical potential of solar collectors in providing hot water for hotels is found around 25,386 square meters. REFERENCES [1]
[2]
Ac
This figure represents the technical potential of solar collector area to cover 75% of the hot water demand for the current hotel buildings in Libya. V.
CONCLUSIONS
This study was conducted to determine the contribution of solar energy in providing part of the requirements of hot water in the hotel sector in Libya. The study was adopted to collect data through questionnaires that prepared and distributed to most of the hotels, as well as the documents and information that has been obtained from the Ministry of Tourism. It has been shown through this study that there is a high potential for investment in this sector for providing hot water by solar energy technology. In addition, the economic returns that can be earned by the owners of hotels in the event of using solar energy systems. There is also important environmental payoff, but invisible to many people as a result of replacement systems, solar water heating replace electric heaters, and so by avoiding the emission of large amounts of harmful gases to the environment. This will greatly help in the event of the extended use of such
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