Energy xxx (2013) 1e12
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Energy and exergy utilization efficiencies and emission performance of Canadian transportation sector, 1990e2035 F. Motasemi a, Muhammad T. Afzal a, *, Arshad Adam Salema a, M. Moghavvemi b, c, M. Shekarchian d, F. Zarifi d, R. Mohsin e a
Department of Mechanical Engineering, University of New Brunswick, P.O. Box 4400, Fredericton, NB E3B 5A3, Canada Department of Electrical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia Centre for Research in Applied Electronics (CRAE), University of Malaya, 50603 Kuala Lumpur, Malaysia d Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia e Gas Technology Center, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia b c
a r t i c l e i n f o
a b s t r a c t
Article history: Received 27 April 2013 Received in revised form 23 September 2013 Accepted 29 September 2013 Available online xxx
Transportation sector of Canada is the second largest energy consuming sector which accounts for 30% of the total energy consumption of the country in 2009. The purpose of this work was to analyze the energy, exergy, and emission performance for four different modes of transport (road, air, rail, and marine) from the year 1990e2035. For historical period, the estimated overall energy efficiency ranges from 22.41% (1991) to 22.55% (2006) with a mean of 22.48 0.07% and the overall exergy efficiency ranges from 21.61% (2001) to 21.87 (2006) with a mean of 21.74 0.13%. Energy and exergy efficiencies may reach 20.95% and 20.97% in the year 2035 respectively based on the forecasted data. In comparison with other countries, we found that in the year 2000 the overall energy and exergy efficiencies for Canadian transportation sector were higher than Jordan, China, Norway, and Saudi Arabia but lower than Turkey and Malaysia. Between the year 1990e2009, the highest amount of emission produced in each subsector was: road CO2 (80%), NOx (72%), and CO (carbon monoxide) (96%); air SO2 (86%); rail NOx (6%) and marine NOx (7%). The road subsector produced the highest amount of emissions. Ó 2013 Elsevier Ltd. All rights reserved.
Keywords: Energy Exergy Emission Canadian transport Prediction
1. Introduction Energy is consumed in various forms by different sectors such as transportation, industry, agriculture, residential, as well as commercial [1]. Statistics have shown that energy consumption in the industrial countries has increased drastically in the past decades which has led to decrease in natural resource’s supplies and an increase in damage to the environment [2]. Canada is blessed with abundant energy resources to meet its domestic needs as well as excess supplies for export [3]. Transportation plays an important role for the sustainability of the society in order to have a meaningful life of the people [4]. In Canada, transportation sector contributed about 4.2% of the country’s GDP (Growth Domestic Products) in 2005 [5]. This sector has four major modes namely road, air, rail, and marine [6]. It includes more than 1.4 million kilometers of road network, 10 major international airports, 300 smaller airports, 72,093 km of functioning railroad track, and more
* Corresponding author. Tel.: þ1 506 453 4880; fax: þ1 506 453 5025. E-mail address:
[email protected] (M.T. Afzal).
than 300 commercial ports and harbors that provide access to three oceans, the Great Lakes, and the St. Lawrence Seaway [7]. This sector is the second largest end-user in the country which approximately consumed 30% of the total Canada’s energy demand in 2009 with an annual growth rate of 37.2% between 1990 and 2009 [6]. The annual petroleum product’s consumption for Canada increased from 79.6 in 1990 to 103.1 (million tonnes) in 2011 [8]. More than 90% of total energy demand in transportation sector of Canada was depended on petroleum products in the year 2009. The different types of fuel consumed by transportation sector are gasoline, diesel, natural gas, propane, ethanol, electricity, aviation turbo fuel, aviation gasoline, and heavy fuel oil. Hence, Canada face two major challenges, one is to sustain the supply of fuel and security and the other is concern about the environmental impact. The world is recently confronted with global warming, climate change and air pollution because of tremendous amount of energy use. Transportation is known as the most significant sector that expedites this environmental degradation among the entire economic sectors [9]. Growth in transportation energy demand brings some advantages and disadvantages. It makes an easy access to any
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Nomenclature
T40 3
BAU EEP EF FC FFV Fr GDP GHG H P TM T Th0
business-as-usual Ethanol Expansion Program emission factor fuel consumption flexible fuel vehicle energy fraction Growth Domestic Products greenhouse gas lower heating value (kJ/kg) pressure (atm) total emission temperature (K) overall weighted mean energy efficiency (%)
geographical location in the world and it causes noise, air and water pollution [10]. Transport sector accounted about 14% of GHG (greenhouse gas) emissions and 13.5% of global warming [11,12]. Therefore, an investigation into energy and emission performance of transportation sector will provide important information for Canadian government, energy and environmental policy makers. The concept of exergy analysis has received much attention recently as researchers would like to identify the pertinent losses and inefficiencies in different sectors [13,14]. Energy and exergy analysis including modeling of the transportation sector has been done for different countries such as Turkey [15e17], Saudi Arabia [18], Norway [19], Jordan [20], Malaysia [21], UK [22], Greek [23] and China [4,24]. Among these, none of them have predicted future energy and exergy analysis. In context to Canada, Rosen and co-worker has done energy and exergy analysis of the economy including transportation before the year 1990 [25e27]. Recently, an exergy analysis was conducted for the transportation sector of Canada, but for a single province named Nova Scotia [28]. It is observed that from the year 1990 to date, no report was found on energy and exergy analysis work for Canada. Furthermore, emission performance of Canadian transportation sector is lacking in the literature. From our observation, this is the first kind of detailed energy and emission analysis study done for the whole Canada. The aim of this study is to present energy and exergy utilization efficiencies and emission performance of transport sector in Canada. This study encompasses the four subsectors of transport including road, air, rail and marine. The total energy consumed in each subsector was predicted by the type of fuel using business-asusual (BAU) scenario approach from the year 2013e2035 based on the available data from 1990 to 2009. Lastly, the overall energy and exergy efficiencies of Canada transport sector were compared with other countries for the year 2000. This study can provide useful information for the policy makers in Canada to set guidelines for transport sector. 2. Survey data The necessary data is collected from Statistics Canada reports published between 1990 and 2009 [6]. Table 1 illustrates some of the typical values of energy source used in transportation sector for exergy grade function, lower heating value, and chemical exergy. Specific chemical exergy (3 f) of fuels at T0 and P0 is approximately equals to the multiplication of Hff and gff [4,13,15,16,18,23,24,29,30]. Table 2 shows the energy consumption for road, air, rail, and marine subsectors. The energy efficiency data for these subsectors were obtained from Reistad [32]. Rated and part load efficiencies
h j g m
overall weighted mean exergy efficiency (%) specific value of exergy (kJ/kg) energy efficiency exergy efficiency exergy grade function chemical composition
Subscripts ff fossil fuel f fuel n year et emission type i energy form j transportation mode 0 environment state
are different for all types of vehicles, therefore the part load efficiency for road, rail, marine, and air is assumed to be 22%, 28%, 15% and 28%, respectively [15,33].
3. Methodology 3.1. Estimation of energy consumption The data on energy consumption by different subsectors of Canadian transportation sector from 1990 to 2009 was available however the energy consumption from the year 2010e2035 was predicted based on the available data. Thus, the energy consumed by subsector in each year from 2013 to 2035 should be forecasted to obtain a better understanding of future energy demand of the country. Business-as-usual (BAU) scenario was assumed to estimate energy consumption keeping in view that no new policies are implemented. There are several methods for predicting future data; the one that is widely used is polynomial curve fitting. This method tries to describe the relationship between a variable X as the function of available data and a response Y that seeks to find a smooth curve for the best fit of the data. Mathematically, a polynomial of order k in X can be expressed in the following equation form [34,35]:
Y ¼ C0 þ C1 X þ C2 X 2 þ / þ Ck X k
(1)
3.2. Energy and exergy modeling The exergy concept can be used for determination of energy quantity to compare the quality of different energy sources. It is based on both first and second laws of thermodynamics and it can eliminate the limitations of first law of thermodynamics [36,37]. It is known as a powerful tool to understand the utilization of energy Table 1 Properties of several fuels at 25 C and 1 atm pressure [31]. Fuel
Hff (kJ/kg)
3f
Gasoline Natural gas Heavy fuel oil Aviation gasoline Aviation turbo fuel Diesel Electricity Propane Ethanol
47,849.00 55,448.00 47,405.00 46,117.00 46,117.00 39,500.00 3600.60 50,350.00 29,700.00
47,394.00 51,702.00 47,101.00 45,897.00 45,897.00 42,265.00 3600.60 48,757.68 30,389.57
(kJ/kg)
gff 0.99 0.93 0.99 1.00 1.00 1.07 1.00 0.97 1.02
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3
Table 2 Energy consumption and process data of the Canadian transportation sector. Year
1990
Mode of transport
Road
Air Rail Marine
1991
Road
Air Rail Marine
1992
Road
Air Rail Marine
1993
Road
Air Rail Marine
1994
Road
Air Rail Marine
1995
Road
Air
Main fuel types
Energy consumption
Energy efficiency (%)
PJ
%
Rated load
Estimated operating
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
3.10 1.66 1067.05 333.95 0.00 35.36 5.51 181.93 89.47 46.38 60.14 1824.54
0.17 0.09 58.48 18.30 0.00 1.94 0.30 9.97 4.90 2.54 3.30 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
3.07 2.09 1033.00 315.30 0.00 36.71 4.18 163.29 82.87 44.19 66.37 1751.06
0.18 0.12 58.99 18.01 0.00 2.10 0.24 9.33 4.73 2.52 3.79 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
2.94 2.33 1054.45 320.46 0.00 42.49 3.76 169.02 86.66 43.87 65.81 1791.79
0.16 0.13 58.85 17.88 0.00 2.37 0.21 9.43 4.84 2.45 3.67 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
2.91 2.40 1083.80 344.53 0.00 31.57 3.74 161.65 86.36 40.94 55.84 1813.74
0.16 0.13 59.75 19.00 0.00 1.74 0.21 8.91 4.76 2.26 3.08 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
2.96 2.49 1119.13 385.67 0.00 29.70 3.70 170.81 89.34 44.05 59.88 1907.72
0.16 0.13 58.66 20.22 0.00 1.56 0.19 8.95 4.68 2.31 3.14 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel
2.99 2.35 1112.41 422.30 0.00 32.81 4.14 183.17
0.15 0.12 57.26 21.74 0.00 1.69 0.21 9.43
28 28 28 28 28 28 35 35
22 22 22 22 22 22 28 28 (continued on next page)
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Table 2 (continued ) Year
1996
Mode of transport
Estimated operating
e e e
28 15 15
Road
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
3.02 2.22 1123.11 431.81 0.00 30.89 3.88 205.52 79.13 45.05 54.88 1979.53
0.15 0.11 56.74 21.81 0.00 1.56 0.20 10.38 4.00 2.28 2.77 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
2.97 2.55 1146.16 475.35 0.00 28.27 3.70 210.94 80.22 43.41 56.70 2050.26
0.15 0.12 55.90 23.18 0.00 1.38 0.18 10.29 3.91 2.12 2.77 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
2.86 2.55 1191.07 478.23 0.00 27.00 3.88 222.82 76.55 44.36 74.82 2124.14
0.13 0.12 56.07 22.51 0.00 1.27 0.18 10.49 3.60 2.09 3.52 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
3.01 2.22 1217.67 501.50 0.00 22.63 3.58 233.95 81.06 45.61 65.89 2177.11
0.14 0.10 55.93 23.03 0.00 1.04 0.16 10.75 3.72 2.09 3.03 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
3.12 2.37 1214.10 529.06 0.00 15.92 3.58 235.89 83.08 46.21 67.78 2201.12
0.14 0.11 55.16 24.04 0.00 0.72 0.16 10.72 3.77 2.10 3.08 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol
3.08 1.96 1218.42 523.11 0.00
0.14 0.09 55.71 23.92 0.00
28 28 28 28 28
22 22 22 22 22
Road
Road
Air Rail Marine
Road
Air Rail Marine
Road
Air Rail Marine
2001
Rated load
4.16 2.32 2.91 100.00
Rail Marine
2000
%
80.91 45.16 56.57 1942.81
Air
1999
Energy efficiency (%)
PJ Diesel Diesel Heavy fuel oil Total
Rail Marine
1998
Energy consumption
Rail Marine
Air
1997
Main fuel types
Road
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5
Table 2 (continued ) Year
Mode of transport
Air Rail Marine
2002
Road
Air Rail Marine
2003
Road
Air Rail Marine
2004
Road
Air Rail Marine
2005
Road
Air Rail Marine
2006
Road
Air Rail Marine
2007
Road
Main fuel types
Energy consumption
Energy efficiency (%)
PJ
%
Rated load
Estimated operating
Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
17.03 3.52 215.13 81.66 45.66 77.51 2187.06
0.78 0.16 9.84 3.73 2.09 3.54 100.00
28 35 35 e e e
22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
3.35 1.74 1240.67 542.59 0.00 12.36 3.47 224.59 74.07 45.75 64.76 2213.35
0.15 0.08 56.05 24.51 0.00 0.56 0.16 10.15 3.35 2.07 2.93 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
3.39 1.75 1259.98 587.40 0.00 11.70 3.18 222.49 73.82 36.25 66.82 2266.76
0.15 0.08 55.58 25.91 0.00 0.52 0.14 9.82 3.26 1.60 2.95 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
3.46 1.75 1287.43 624.57 0.00 12.67 2.94 246.16 75.05 45.13 69.06 2368.22
0.15 0.07 54.36 26.37 0.00 0.53 0.12 10.39 3.17 1.91 2.92 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
3.53 1.88 1272.31 659.25 5.99 10.27 2.95 255.84 78.88 43.67 67.48 2402.07
0.15 0.08 52.97 27.45 0.25 0.43 0.12 10.65 3.28 1.82 2.81 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
3.50 1.88 1272.84 659.36 6.13 11.34 2.97 252.75 81.35 42.56 56.93 2391.60
0.15 0.08 53.22 27.57 0.26 0.47 0.12 10.57 3.40 1.78 2.38 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
2.48
0.10
28
Electricity
22 (continued on next page)
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Table 2 (continued ) Year
Mode of transport
Main fuel types
Air Rail Marine
2008
Road
Air Rail Marine
2009
Road
Air Rail Marine
Energy consumption
Energy efficiency (%)
PJ
%
Rated load
Estimated operating
Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
1.88 1297.80 693.40 29.49 12.05 3.09 256.63 86.46 39.56 69.39 2492.23
0.08 52.07 27.82 1.18 0.48 0.12 10.30 3.47 1.59 2.78 100.00
28 28 28 28 28 35 35 e e e
22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
2.35 1.88 1280.77 717.99 30.62 12.81 3.00 251.94 90.91 35.02 65.84 2493.14
0.09 0.08 51.37 28.80 1.23 0.51 0.12 10.11 3.65 1.40 2.64 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
Electricity Natural gas Gasoline Diesel Ethanol Propane Aviation gasoline Aviation turbo fuel Diesel Diesel Heavy fuel oil Total
2.48 1.89 1310.29 703.87 34.60 11.25 2.86 240.22 87.93 30.00 58.00 2483.40
0.10 0.08 52.76 28.34 1.39 0.45 0.12 9.67 3.54 1.21 2.34 100.00
28 28 28 28 28 28 35 35 e e e
22 22 22 22 22 22 28 28 28 15 15
efficiency and attain the efficient and effective use of fuels for different sectors of economy at national levels [38,39]. According to the first law of thermodynamics, energy is neither destroyed nor created and remains constant during a process. On the other side, from the second law of thermodynamics, exergy is destroyed when the temperature of the process changes and it accounts for the irreversibility of a process because of entropy generation [40]. In fact, exergy is the maximum amount of work the system can perform in the thermodynamic equilibrium with its reference environment [41,42]. The standard atmosphere will be chosen as the reference environment for evaluation of the exergy flows associated with a vehicle [24,43]. The basic components of the energy and exergy analysis are well-established and can be found in previous articles [18,44]. Hence, in this section, some of the key features of energy and exergy analysis applied to transportation sector of Canada are discussed. Table 3 Potential environmental impacts from fossil fuels by transportation sector [50,51]. Fuels
Emission factors CO2 (kg/GJ)
SO2 (gr/GJ)
NOx (gr/GJ)
CO (gr/GJ)
Gasoline Diesel Propane Natural gas Aviation gasoline Aviation turbo fuel Heavy fuel oil Ethanol
72.79 73.99 65.00 53.90 73.00 72.00 73.99 57.00
0.46 0.47 0.00 0.00 22.99 22.99 0.47 0.00
111.72 257.64 148.53 488.00 859.00 250.57 257.64 130.00
2225.97 97.20 749.67 214.00 6972.00 229.89 97.20 589.00
3.2.1. Chemical exergy The chemical exergy of a substance is the maximum work that can be obtained from it by bringing it to chemical equilibrium in a given reference environment at a constant temperature and pressure [13,45]. It has been suggested that for the fuels used in the transport system, only chemical exergy is significant [46,47]. The chemical exergy can be derived by Eq. (2) which is the multiplication of the fuel exergy grade function and fuel lower heating value: 3 ff
¼ gff Hff
(2)
3.2.2. Energy and exergy efficiencies The energy h and exergy j efficiencies can be derived by the equation below:
h ¼ ðEnergy in products=Total energy inputÞ
(3)
j ¼ ðExergy in products=Total exergy inputÞ
(4)
The relationship between these efficiencies can be expressed by Refs. [13,48]:
j ¼ h=gff
(5)
3.2.3. Mean and overall energy and exergy efficiencies calculations The overall weighted mean energy efficiency Th0 is expressed in Eq. (6) as below. As it shows, the weighted mean energy efficiencies can be calculated by multiplying the energy efficiency of each mode of transport (hj) with the energy fraction in that mode of transport (Fri,j) and the fuel it consumes. The overall weighted mean energy
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7
efficiency is the summation of the weighted mean energy efficiencies.
Th0 ¼
X
hj Fri;j
(6)
i;j
Similarly, the weighted exergy efficiencies can be calculated by multiplying weighting factors with the energy efficiency of that mode divided by exergy grade function (gj) of the fuels. The overall weighted mean exergy efficiency is the summation of the weighted mean exergy efficiencies.
T40 ¼
!
X
hi=g
j
i;j
Fri;j
(7)
3.3. Emission analysis Increase in the atmospheric concentration of greenhouse gases such as CO2 (carbon dioxide), SO2 (sulfur dioxide), NOx (nitrogen oxide), and CO (carbon monoxide) by transport sector is an alarming indication for the environment and human. Emission estimation by using emission factors is not necessarily the best way, but it is the only feasible option due to the lake of any continuous emission measurements or frequent stack measurement data [49]. Thus, in order to determine the potential environmental impacts by this sector, the emission factors of CO2, SO2, NOx, and CO for different fuels are collected and shown in Table 3. The table shows emission factor of propane, ethanol, and natural gas in SO2 production is negligible. Gasoline has the highest emission factor for CO and the least NOx emission factor. In order to have effectual policies to solve the problem of pollution, emission measurement is the first step. The total emission pattern of transportation sector in Canada for each type of fuel in a certain year can be calculated by the following equation:
TMet n ¼
X
FCnf EFet f
(8)
f
The total amount of emission (TM) by emission type (et, CO2, SO2, etc.) in year n would be the summation of multiplication of the fuel consumption (FC) in that specific year to the related emission factor (EF, kg/GJ or gr/GJ) of that specific type of emission for that fuel (f). 4. Results and discussion 4.1. Energy consumption and prediction
Fig. 1. Historical and predicted energy consumption for road subsector.
was predicted from 2010 to 2035 by a second order polynomial which has been generated according to the energy consumption in these subsectors from 1990 to 2009. Table 4 shows the second order polynomial curve fittings applied to each fuel in different subsectors. Figs. 1e3 demonstrate the historical and predicted energy consumptions (by fuel type) for road, air, rail and marine subsectors, respectively. The result indicates that the total energy consumption in transport sector of Canada would increase by 35% from the year 2009e2035. Gasoline is the most popular type of fuel in the road subsector whose consumption is 1.8 times higher than the diesel due to use of cars owned by private individuals. This might be because of increase in real income which stimulates leisure-related travels [4]. In contrast to this, the diesel consumption in the year 2009 was about 12 times higher than petrol for road subsector in China [4] and 2.8 times higher than gasoline in Turkey for the year 2006 [17], while in Malaysia the petrol consumption was about 1.5 times higher than diesel in the year 2003 [13]. The use of natural gas in transport sector is expected to increase drastically in future. There are few reasons for this increase, firstly they help to reduce the greenhouse gas (GHG) emissions, secondly natural gas is emerging as a potential fuel for transport sector, thirdly the operating costs are lower because natural gas is typically 15e30% lower in price than diesel fuel, lastly the noise levels is minimized by using natural gas transport fleets which are beneficial in urban
Table 2 shows that the total energy consumption in transport sector has increased steadily. The consumption of each type of fuel Table 4 The second order polynomial curve fittings applied to each fuel in different subsectors. R2
Subsector
Fuel
Equation
Road
Gasoline Electricity Natural gas Diesel Ethanol Propane
Y Y Y Y Y Y
Air
Aviation gasoline Aviation turbo fuel
Y ¼ 0.0001X2 0.0098X þ 0.2605 Y ¼ 0.0038X2 0.0253X þ 9.7282
0.9476 0.9039
Rail Marine
Diesel Diesel Heavy fuel oil
Y ¼ 0.0022X2 0.1137X þ 4.9286 Y ¼ 0.0009X2 0.0759X þ 2.6911 Y ¼ 0.0006X2 0.0581X þ 3.5412
0.9027 0.9096 0.6532
¼ ¼ ¼ ¼ ¼ ¼
0.0024X2 0.3393X þ 59.7110 0.0015X2 0.0322X þ 0.2696 0.0079X2 0.1611X þ 0.6715 0.0263X2 þ 1.1256X þ 15.4330 0.0037X2 0.0236X 0.0600 0.0021X2 0.1454X þ 2.3339
0.9789 0.9838 0.9894 0.9644 0.9754 0.9391
Fig. 2. Historical and predicted energy consumption for air subsector.
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Fig. 5. Futuristic overall energy and exergy efficiencies of Canadian transportation sector.
Fig. 3. Historical and predicted energy consumption rail and marine subsectors.
areas [52]. The demand for ethanol is expected to increase drastically in future to run the transport sector due to environmental and economic benefits. Another advantage of ethanol is that, since 1980s the vehicles can use gasoline that contains ethanol to a certain percentage [53]. For instance, most gasoline-powered vehicles can run on a blend consisting of gasoline and up to 10 percent ethanol, which is available at some regular service stations across Canada. However, ethanol more than 10% can be added to gasoline but not above 85% because of cold climate condition in Canada. The Ethanol Expansion Program (EEP), Canada, aims to increase the use of ethanol to reduce environmental impact, because the higher oxygen content in ethanol will result in a more complete burn of the fuel and fewer emissions. Transport Canada has justified the use of ethanol by developing Flexible Fuel Vehicles (FFVs). The economic benefits of ethanol attributes to regional economic growth, job creation, particularly to farmers and rural communities [54]. A significant drop in aviation gasoline was observed (Fig. 2) while the consumption of aviation turbo fuel was increased. Furthermore, the fuels demand in rail and marine subsectors (Fig. 3) was found to fluctuate from time to time. The rail subsector in Canada only uses diesel fuel.
22.48 0.07% and the estimated overall exergy efficiency ranges from 21.61% (2001) to 21.87 (2006) with a mean of 21.74 0.13%. From Fig. 5 the energy efficiencies are higher than exergy efficiencies because the later take into account the losses due to irreversible process. The wave pattern of energy and exergy efficiencies was simply due to the energy consumption pattern particularly in air and rail subsectors. It can be noted from Table 1 that natural gas has the highest chemical exergy value and lowest exergy grade function which results in highest energy and exergy efficiencies
4.2. Overall energy and exergy efficiencies Fig. 4 illustrates the overall energy and exergy efficiencies between 1990 and 2009. The estimated overall energy efficiency ranges from 22.41% (1991) to 22.55% (2006) with a mean of
Fig. 4. Historical overall energy and exergy efficiencies of Canadian transportation sector.
Fig. 6. Energy (PJ) flow diagram of Canadian transport sector for 2009.
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compared to other fuels. In addition, natural gas was used for road subsector only in Canada. Thus, it can be concluded that using natural gas fuel vehicles can increase the efficiency of the transportation sector. Fig. 5 shows the overall energy and exergy efficiencies calculated based on the predicted energy consumption in the transport sector of Canada between 2013 and 2035. The overall energy and exergy efficiencies would decline as can be seen from Fig. 5, provided BAU policy is applied in the transport sector of Canada. Energy and exergy efficiencies may reach 20.95% and 20.97% in the year 2035 respectively based on the forecasted data. This decrease in energy and exergy efficiencies predicted can be due to drastic variation in energy consumption by road and air subsectors of Canada. This data carries a large potential for the improvement in energy and exergy efficiency. Figs. 6 and 7 provide information about the energy and exergy input and output in the form of product and losses respectively for each subsector in the year 2009. It was found that road subsector is the most efficient subsector with energy efficiency of 18.29% and exergy efficiency of 17.99% as compared to air subsector with energy and exergy efficiencies of 2.74%, rail subsector with energy efficiency of 1% and exergy efficiency of 0.92%, and marine subsector with energy efficiency of 0.53% and exergy efficiency of 0.52%. Similarly, Saidur et al. [13] found road subsector as the most efficient and marine the least efficient subsector for Malaysia. The highest portion of energy (1310.30 PJ) was consumed in form of
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Fig. 8. Energy and exergy efficiencies of the transportation sector in some countries including Canada in 2000.
gasoline in the road subsector in 2009. Even though, the energy product of gasoline was higher than other fuels but it resulted in higher loss as well (1022.03 PJ). Fig. 8 presents a comparison of the overall energy and exergy efficiencies of Canada’s transport sector with Turkish, Saudi Arabian, Malaysian, Jordanian, Norwegian and Chinese transportation sectors. It was observed that overall energy and exergy efficiencies in Turkey were the highest between the selected countries. The values for Malaysia were slightly higher than Canada. Additionally, it is found that the energy and exergy efficiencies of the Canadian transportation sector are higher than that of Norwegian, Chinese, Jordanian, and Saudi Arabian. As the types of fuels in these countries are almost the same, it seems that this difference in energy and exergy efficiencies is due to the type of vehicles and dissimilar structure of transport sector in these countries. Although we understand that these countries differ considerably in terms of geography and other factors, the comparison was made to draw the attention of the readers. 4.3. Emission analysis The emission production due to fuel consumption in road, air, rail, and marine subsectors are illustrated in Figs. 9e12. These figures clearly show that CO2 is the largest emitted gas from each subsector. In road subsector, there was a gradual increase in production of CO2 from 1990 to 2009. The predicted data depicts that CO2 might increase till 2024 and there on it will decrease slightly. The overall emission (1990e2009) of CO2 was approximately 81%, 10%, 5%, and 4% from road, air, marine, and rail subsectors,
Fig. 7. Exergy (PJ) flow diagram of Canadian transport sector for 2009.
Fig. 9. CO2, NOx, CO, (ton 105) and SO2 (ton) emissions in road subsector.
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Fig. 10. CO2 (ton 106), NOx, CO, and SO2 (ton 103) emissions in air subsector.
respectively. The CO2 production from marine, road, and rail is expected to remain plateau in the future except air subsector which may show rapid growth. CO was the second largest emission contributor for road and air from 1990 to 2009. Moreover, the trend of CO was almost similar to CO2 in all subsectors for past and future. Road subsector alone is known as the main producer of CO with more than 97% of the total produced CO in the entire transport sector in 2009. It was observed from the predicted emission results that air subsector may produce high amount of CO in the future while the CO emission levels from other subsectors will be maintained. Road subsector generated greater amount of NOx due to use of high consumption of diesel compared to other subsectors. Road and air subsectors emitted about 75% and 14% of the total produced NOx from the transport sector in 2009. Slightly smooth increase trend was found in road and air subsectors for NOx production, while a wavy pattern was observed for marine and rail. In future, a sharp increase in NOx is predicted for air subsector. However, rail subsector is expected to produce less NOx and other subsectors may show a slight increase. The largest contributor of SO2 was air subsector amounting about 85% in 2009. This might be because of high sulfur content in the aviation fuels. Road, marine and rail are the second, third and fourth largest producers of SO2, respectively. In general diesel and heavy fuel oil has high sulfur content compared to gasoline. The historical trend of SO2 was almost similar to that of NOx. After this year 2013, SO2 is anticipated to increase rapidly by air subsector due to the increase in the demand of aviation turbo fuel (Fig. 2) while other subsector may show even SO2 profile. Diesel is commonly used as fuel in road, rail and marine subsectors to move the industrial and consumer goods and passengers
Fig. 11. CO2 (ton 106), SO2 (ton), NOx, CO (ton 103) emissions in marine subsector.
Fig. 12. CO2 (ton 106), SO2 (ton), NOx, and CO (ton 103) emissions in rail subsector.
Fig. 13. Effect of replacing gasoline and diesel with natural gas on the overall energy and exergy efficiencies for the year 2020 (BAU e business-as-usual).
from one place to another. Road subsector alone produced 85% of emission caused by diesel, while rail and marine emitted 15% of pollution in 2009. 4.4. Retrofitting as an effectual scenario The results revealed that the road subsector seems to be the main consumer of gasoline and diesel in Canada. According to the statistics, it accounted for 19% of total greenhouse gas (GHG) emissions in Canada in which light-duty passenger cars and trucks alone accounted about 12% in 2009 [55]. Retrofitting the gasoline and diesel in this subsector can be an effective scenario to improve the transport exergy efficiency and more importantly this would reduce the environmental impact. The impact of reducing the
Fig. 14. Effect of replacing gasoline and diesel with natural gas on the emission (CO2 (ton 106), SO2 (ton), NOx, and CO (ton 103)) for the year 2020.
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F. Motasemi et al. / Energy xxx (2013) 1e12
consumption of gasoline and diesel on the energy and exergy efficiencies by replacing it with eco-friendly fuels such as natural gas for the year 2020 is shown in Fig. 13. There will be improvement in the exergy efficiency if the natural gas is replaced with gasoline and diesel by 10e60% as compared to BAU scenario. However, energy efficiency was found to remain stable. The exergy efficiency might improve by 0.53% (10% scenario) to 3.73% (60% scenario). Further, this retrofit will also lead to decrease in CO2, SO2, and CO emission production tremendously, while a slightly increases in the NOx production could be observed as shown in Fig. 14. The amount of CO can be decreased significantly by 8.8% (10% scenario) to 94.2% (60% scenario). These could not only help Canada to reduce the greenhouse gas emissions but also a global leader to save and protect the environment. 5. Conclusions Exergy can be used as an effective tool to describe the use of energy resources and to determine the future energy scenario of a country or region. It can provide an important knowledge and understanding to identify where large improvements could be obtained by applying efficient technologies and using more efficient energy resource conversions. In Canada, road subsector was the highest energy consumer which accounted for 83% of the total transport energy demand in 2009. However, it appears to be the most energy and exergy efficient compared to air, rail, and marine. The average energy and exergy efficiency values of Canadian transport sector indicate that there is an enormous potential for improving the efficiencies. The overall energy and exergy efficiencies for Canadian transport sector were found to be higher than that of Jordan, China, Norway, and Saudi Arabia but lower than Turkey and Malaysia in the year 2000. The emission production was directly proportional to the energy consumed by transport sector. CO2 was the largest pollutant emitted by the transport sector followed by CO, NOx, and SO2. The road subsector produced the largest amount of CO2 in Canada. Certainly, this study can be important for policy makers, energy researchers, industrial energy users and producers in Canada to get the understanding about the performance of this sector. It can be helpful to policy makers to properly plan and manage the energy resources since there exists large energy and exergy losses by keeping in view the environmental impacts. Based on the present study, the type of the fuel used is one of the most important factors which affect the energy and exergy utilization efficiencies, and the emission performance of Canadian transportation sector. In road subsector, gasoline and diesel were the main fuels by 53% and 28% of the total transport energy consumption in the year 2009, respectively. Retrofitting these fuels with other eco-friendly fuels such as natural gas was suggested as optimal scenarios in this study. The results for a year of 2020 showed a great potential of improvement in exergy efficiency and reduced environmental impacts. For instance, the exergy efficiency was improved by 0.53% (10% scenario) to 3.73% (60% scenario) and the amount of CO can be reduced remarkably by 8.8% (10% scenario) to 94.2% (60% scenario). Usage of bio-fuels can help in reducing the GHG emissions. Since road is the highest energy consuming subsector, the following recommendations can overall improve the economic and environmental aspect of Canadian transportation sector: The forecasted data presented in this study can help to develop policies to make Canadian transport sector more efficient. Public transport systems such as Light Rail Transit (LRT), monorail, bus, etc. should be encouraged to use green fuels. High fuel efficient, hybrid, green fuel vehicles should be promoted.
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Electricity produced from sustainable and renewable sources such as wind, biomass, and hydropower should have a greater share in future energy mix of Canada.
Acknowledgment Collaboration of University of New Brunswick, University of Malaya, and Universiti Teknologi Malaysia is highly appreciated.
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