Potential Environmental Values of Wasteto-Energy Facilities in Saudi Arabia
Omar K. M. Ouda & Huseyin M. Cekirge
Arabian Journal for Science and Engineering ISSN 1319-8025 Arab J Sci Eng DOI 10.1007/s13369-014-1311-4
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Author's personal copy Arab J Sci Eng DOI 10.1007/s13369-014-1311-4
RESEARCH ARTICLE - CIVIL ENGINEERING
Potential Environmental Values of Waste-to-Energy Facilities in Saudi Arabia Omar K. M. Ouda · Huseyin M. Cekirge
Received: 16 September 2013 / Accepted: 30 April 2014 © King Fahd University of Petroleum and Minerals 2014
Abstract Toward diversifying the sources of electricity and ensuring the sustainability of power generation, the Kingdom of Saudi Arabia (KSA) is proposing an impressive plan for renewable energy utilization including waste-to-energy (WTE) facilities. The environmental values of WTE facilities in KSA have never been investigated. This research forecasted the potential environmental values of WTE facilities in KSA in the context of energy demand, greenhouse gas emission, and landfill area in comparison with complete landfilling option up to year 2032. Two scenarios were developed: Mass Burn with Recycling and Mass Burn. The research results have shown magnificent environmental values for WTE facilities. The Mass Burn with Recycling scenario shows potential energy demand reduction of about 55.6 million barrels of crude oil, greenhouse gas emission reduction of about 15.2 million metric ton carbon equivalent per year (MTCE/year), and landfill area saving of about 95.3 % in comparison with complete landfilling. Mass Burn scenario shows potential energy demand reduction of about 9.9 million barrels of crude oil, greenhouse gas emission reductions of about 4.8 million MTCE/year, and landfill area saving of about 90 % in comparison with landfilling. This research results shall support Saudi officials’ decision to develop WTE facilities in the Kingdom.
Keywords Saudi Arabia · Waste-to-energy · Environmental values · Energy demand · Greenhouse gas · Landfill area saving
1 Introduction
O. K. M. Ouda (B) Department of Civil Engineering, Prince Mohamed Bin Fahd University, Al Khobar, Kingdom of Saudi Arabia e-mail:
[email protected];
[email protected] H. M. Cekirge Department of Mechanical Engineering, Prince Mohamed Bin Fahd University, Al Khobar, Kingdom of Saudi Arabia
The KSA owns the world’s largest crude oil reserves and is currently the largest producer [1,2]. The revenues generated from oil have contributed to large-scale socioeconomic development and major increases in country-wide standards of living since the early 1970s [1,2]. This development has come with a substantial increase in population, urbanization, and an influx of expatriate workers [1,2]. The population has dramatically increased from 7 million in 1975 to about 27 million in 2010 at an annual average growth rate of 3.4 [3].
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The population growth was also coupled with an increase in the urbanization level, with the urban population rising from about 50 % of the total population in 1970 to about 80 % in 2000 [3]. There are seven major urban areas in the KSA with a population of 1 million or more: Riyadh, the capital, with 5.2 million, Jeddah with 3.4 million, the Dammam area with 2.0 million, Makka with 1.7 million, Madinah with 1.2 million, Al-Hassa with 1.1 million, and Al-Taif with 1.0 million [3]. Population growth, urbanization, and standard of living improvement have resulted in the rapid growth of the countrywide’s Municipal Solid Waste (MSW) generation and electricity demand [4–8]. Municipalities are managing the MSW system in the KSA [4–6]. The MSW practice in the KSA is simple: collect and get rid of it by dumping it in nearest open landfill sites. The KSA currently generates about 13.8 million tons of MSW in 2010 [1]. Kingdom of Saudi Arabia’s electricity demand grew annually about 5.8 % between 2006 and 2010 [7]. The current electricity peak demand is about 55 GigaWatt (GW) which is typically met through conventional heavy oil, diesel, and gas power plants spread across the country [8]. The peak electrical demand is projected to reach 120 GW by the year 2032 [8]. In order to diversify the electricity sources and to ensure the sustainability of power generation, the KSA is proposing an impressive plan for renewable energy utilization which includes WTE facilities [9,10]. The two decades
Fig. 1 MSW generation forecast [1]
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plan includes a hybrid feed-in-tariff program and production of up to 54 GW from renewable and nuclear energy sources [10]. Recent study assessed the potential contribution of WTE facilities to total Saudi peak power demand up to the year 2032 based on two scenarios: Mass Burn and Mass Burn with Recycling for the entire country and for seven major urban areas in the KSA [1]. The Mass Burn scenario implied full utilization of MSW for WTE production. The Mass Burn with Recycling assumed removal of all potentially recyclable materials from the waste stream and utilizing the remaining MSW for WTE production [1]. The study assumed a waste generation rate as presented in Fig. 1 and incineration with average conversion efficiency of 25 % was considered for WTE facilities. The analysis showed a potential to produce about 2073 Megawatts (MW) based on a Mass Burn scenario and about 166 MW based on Mass Burn with Recycling scenario which is about 1.73 and 0.14 %, respectively, of the projected 2032 peak electricity demand [1]. The environmental values of WTE facilities in KSA have never been investigated. This research aims to assess the environmental values of WTE facilities in the context of Mass Burn and Mass Burn with Recycling scenarios. The Mass Burn scenario implied full utilization of MSW for WTE production. The Mass Burn with Recycling assumed removal of all potentially recyclable materials from the waste stream and utilizing the remaining MSW for WTE production. The potential MSW generation
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quantity, energy demand reduction, greenhouse gas emission reduction, and landfill area saving are forecasted for the two scenarios up to the year 2032.
Table 2 Net greenhouse gas emission reduction in MTCE per ton of material (US EPA 2006)
2 Methodology
Paper
1.01
0.34
Plastic
0.41
−0.26
Glass
0.50
0.43
Wood
0.54
0.08
Textiles
1.97
0.10
Organic
0.12
0.12
Others (mixed MSW)
0.60
0.18
To forecast the long-term MSW generation quantity, the most recent population census results (2010) was used and the population growth rate was assumed to maintain the historical average of 3.4 % [3]. The MSW production rate was assumed to continue at the current average rate of 1.4 kg/capita/day. The MSW wastes in the KSA composed of 37 % organic material, 28.5 % paper, 5.2 % plastic, 4.6 % glass, 8 % wood, 6.4 % textile, and 10.3 % other [11]. Potential energy demand reductions for the two scenarios options were estimated based on the US EPA approach as documented in the Solid Waste Management and Greenhouse Gas, A life-Cycle Assessment of Emission and Sinks report. The energy reduction is the result of energy saving associated with production, transporting, and manufacturing of raw materials in addition to waste collection and disposal. The report provides potential energy demand reduction values based on life cycle assessment approach for MSW materials. These values can be used by organization interested in quantifying energy demand reductions associated with MSW management practices. Net energy demand reduction compared to landfilling for WTE incineration facility in million Btu/ton of MSW materials is presented in Table 1. These values are regionally generic and have been used to estimate energy demand reductions per ton of Saudi’s MSW for the Mass Burn and Mass Burn with Recycling scenarios in comparison with landfilling up to year 2032. Greenhouse gas emission reduction for the two scenarios was calculated based on US EPA developed and recommended methodology. The methodology is documented in the Solid Waste Management and Greenhouse Gas, A lifeCycle Assessment of Emission and Sinks report [12]. The report provides greenhouse gas emission values based on life cycle assessment approach for MSW materials. These valTable 1 Net energy reduction in million Btu per ton of material (US EPA 2006) Materials
Recycling versus landfilling
Combustion versus landfilling
Paper
8.10
2.40
Plastic
52.94
5.62
Glass
2.65
0.15
Wood
0.21
3.04
Textiles
106.11
5.31
Organic
−0.21
0.93
Others
13.30
2.10
Materials
Recycling versus landfilling
Combustion versus landfilling
ues are generic and can be used by organization interested in quantifying emission reductions associated with MSW management practices. Greenhouse gas emission reduction values by converted MSW to Energy utilizing incineration technology as compared to landfilling option in MTCE/ton of MSW materials are presented in Table 2. These values are regionally generic and can be adapted in the KSA. These values have been used to estimate the greenhouse gas emission reduction (MTCE/ton) of Saudi’s MSW resulted from utilizing WTE facilities in comparison with landfilling for Mass Burn and Mass Burn with Recycling scenarios. Sizing the landfill area requires estimates of the rate at which wastes are discarded at and the density of these wastes. For MSW, the density in a landfall will be somewhere between 500 to 700 kg/m3 , with a reasonable average estimate of about 600 kg/m3 [13]. WTE reduces the amount of MSW deposited at landfill sites; about 90 % volume reduction and 80 % mass reduction [13–15]. The thickness of landfill is typically in the order of 3 m depth [13]. These values were utilized to calculate the landfill area requirements for MSW on hectare and the potential land saving in the context of the Mass Burn and Mass Burn with Recycling scenarios. 3 Results and Discussion MSW generation forecast results for the KSA, and the seven major urban areas are presented in Fig. 1. The KSA currently generates about 13.8 million ton/year of MSW, and this figure is estimated to reach about 26.9 million ton/year in 2032. This is substantial amount of MSW and, if managed wisely, can come with magnificent environmental values including energy reduction, greenhouse gas emission reductions, and landfill area saving as discussed in the following sections. 3.1 Energy Reduction The potential energy reduction was completed under the consideration of the net energy reduction potential for the various components of MSW as presented in Table 1 and the Saudi’s
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Author's personal copy Arab J Sci Eng Table 3 Net energy reduction in million Btu per ton of material for the two scenarios Materials
Waste composition (%)
Paper
28.5
2.31
0.68
Plastic
5.2
2.75
0.29
Glass
4.6
0.12
0.01
Wood
8
0.02
0.24
Textiles
6.4
6.79
Organic
37
Others
10.3
Total (million Btu/Ton)
Mass burn with recycling (million Btu/ton)
Mass burn (million Btu/ton)
0.34 0.34 0.22
11.99
2.13
MSW composition. Table 3 presents the energy reduction per ton of Saudi’s MSW. Two values of the energy reductions per ton of MSW were calculated for the Mass Burn with Recycling scenario and Mass Burn scenario. The results show a potential to reduce energy demand based on Mass with recycling scenario of about 12 million Btu per ton of MSW and about 2.1 million Btu per ton for the Mass Burn scenario. Since an oil barrel contains about 5.8 million Btu [12], applying the Mass Burn with Recycling scenario will save the country about 2.2 barrel of oil per ton MSW. The energy reduction potential in comparison with landfilling for the two scenarios is presented in Figs. 2 and 3. Figure 2 shows
that applying comprehensive recycling program as part of Mass Burn with Recycling scenario will ultimately result in a reduction of energy demand of 28.5 million crude oil barrels at present and about 55.6 million barrels in 2032. Figure 3 shows that Mass Burn scenario will ultimately save about 5.1 million barrels of oil needed to landfill MSW at present and about 9.9 million barrels in 2032. The energy reduction is the result of saving energy associated with production, transporting, manufacturing of raw materials, also waste disposing. The energy saving potential was calculated for the major seven urban areas in KSA toward enhancing local municipalities to implement WTE and recycling projects. 3.2 Greenhouse Gas Emission Reduction Landfills are major source of greenhouse gas, which account for 3.4–3.9 % of global greenhouse gas emissions [16]. During MSW decomposition, large quantities of methane and carbon dioxide are produced. Methane is a major concern, while it is 21 times more detrimental than carbon dioxide as greenhouse gas [16,17]. The potential greenhouse gas reduction in comparison with landfilling for Mass Burn with Recycling and Mass Burn scenarios was calculated. The calculations were completed under the consideration of the net greenhouse gas reduction potential for the various components of MSW as presented in Table 2 and the Saudi’s MSW composition. Table 4 presents the greenhouse gas reduction per ton Saudi’s MSW. Two values of the greenhouse gas
Fig. 2 Energy reduction forecast based on mass burn with recycling scenario
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Fig. 3 Energy reduction forecast based on mass burn scenario
reductions per ton of MSW were calculated for the Mass Burn with Recycling scenario and Mass Burn scenario. The results show the potential to reduce greenhouse gas emission based on Mass with recycling scenario of about 0.61 MTCE/ton of MSW and about 0.18 MTCE/ton of MSW based on Mass Burn scenario. The greenhouse gas reduction potential in comparison with landfilling for the two scenarios is presented in Figs. 4 and 5. Figure 4 shows that applying comprehensive recycling program as part of Mass Burn with Recycling scenario will ultimately result in a reduction of greenhouses gas emission of about 7.8 million MTCE/year at present and about 15.2 million MTCE/year in 2032. Figure 5 shows that Mass Burn scenario will ultimately reduce greenhouse gas by about 2.5 million MTCE/year in comparison with landfill emission at present and about 4.8 million MTCE/year in 2032. The greenhouse gas emission reductions in Mass Burn scenario is primarily due to the thermal conversion of the landfill methane gas to carbon dioxide through incantation. Methane is 21 times more detrimental than carbon dioxide from the global warming perspective [17]. 3.3 Landfill Area Saving The potential land saving in comparison with landfilling for Mass Burn with Recycling and Mass Burn scenarios was calculated up to year 2032. The landfill area requirements
Table 4 Net greenhouse gas reduction in MTCE per ton of material for the two scenarios Materials
Waste composition %
Mass burn with recycling (MTCE/ton of MSW)
Mass burn (MTCE/ton of MSW)
Paper
28.5
0.29
0.10
Plastic
5.2
0.02
−0.01
Glass
4.6
0.02
0.02
Wood
8
0.04
0.01
Textiles
6.4
0.13
0.01
Organic
37.0
0.04
0.04
Others
10.3
0.06
0.02
0.61
0.18
Total (MTCE/ton)
0.98
for disposal of MSW up to year 2032 are presented in Fig. 6. Figure 6 shows a need for about 767 hectare per year (ha/year) of landfill area at present. This area will almost double by the year 2032. The figure presents also landfill area requirements for the seven major urban areas in the Kingdom. The high level of urbanization growth in KSA will add extra pressure in land resources and landfill availability, and this will limit the area available for new landfills or the expansion of existing landfills. The potential land saving based on Mass Burn with
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Fig. 4 Greenhouse gas reduction forecast based on mass burn with recycling scenario
Fig. 5 Greenhouse gas reduction based on mass burn scenario
Recycling and Mass Burn scenarios are presented in Figs. 7 and 8, respectively. The Mass Burn scenario shows a potential to save about 690 ha/year of landfill area which is needed at
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present and about 1,345 ha/year in 2032 in comparison with landfilling. The Mass Burn with Recycling scenario shows a potential to save about 731 ha/year of landfill area which
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Fig. 6 Landfill area forecast based on complete landfilling
Fig. 7 Landfill area saving forecast based on mass burn scenario
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Fig. 8 Landfill area saving forecast based on mass burn with recycling scenario
is needed at present and about 1,424 ha/year in 2032. The land saving for Mass Burn and Mass Burn with Recycling scenario is about 90 and 95.3 %, respectively, in comparison with landfilling. The landfill requirement results for the seven urban areas can be used to support local official’s decision to implement WTE facilities and/or recycling system in their area. WTE incineration facility may also provide other significant environmental benefits. Incineration minimizes leachate and methane formation and odor emissions in comparison with landfilling [14]. The incineration bottom ash can be utilized to produce controlled low-strength material (CLSM). CLSM material can be utilized for a wide range of construction and civil engineering application [18]. Upon development of WTE facility, further site-specific environmental studies should also be conducted. The site-specific study should consider the potential environmental impacts of WTE facility in comparison with landfilling on groundwater quality, soil quality, air quality and smog formation, and surface water and eutrophication potential [19].
4 Conclusion Toward diversifying the sources of electricity and ensuring the sustainability of power generation, the KSA is proposing an impressive plan for renewable energy utilization includes WTE facilities. Recent study assessed the potential contri-
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bution of WTE facilities to total Saudi peak power demand up to the year 2032 based on two scenarios: Mass Burn and Mass Burn with Recycling for the entire country and for seven major urban areas in the Kingdom. The analysis showed a potential to produce about 2,073 Megawatts (MW) based on a Mass Burn scenario and about 166 MW based on Mass Burn with Recycling scenario which is about 1.73 and 0.14 %, respectively, of the projected 2032 peak electricity demand. This research forecasted the potential environmental values of WTE facilities in KSA in the context of energy demand, greenhouse gas emission, and landfill area in comparison with complete landfilling option up to year 2032. The results show potential energy reduction in comparison with landfilling of about 55.6 million barrels and about 9.9 million barrels of crude oil for the Mass Burn with Recycling scenario and Mass Burn scenario, respectively, in the year 2032. The greenhouse gas results show a potential emission reduction of 15.2 and 4.8 million MTCE/year in 2032 for the Mass Burn with Recycling scenario and Mass Burn scenario, respectively, in comparison with landfilling option. The landfill area saving for Mass Burn and Mass Burn with Recycling scenario is about 90 and 95.3 %, respectively, in comparison with landfilling. The research findings showed the magnificent environmental values of two MSW management scenarios over landfilling option regarding energy demand reduction, greenhouses gas emission and landfill area saving. These research
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findings shall support Saudi officials’ potential decision to develop WTE facilities in the Kingdom.
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