Inserting renewable fuels and technologies for transport in Mexico City Metropolitan Area

International Journal of Hydrogen Energy 31 (2006) 327 – 335 www.elsevier.com/locate/ijhydene

Inserting renewable fuels and technologies for transport in Mexico City Metropolitan Area Fabio Manzini∗ Centre for Energy Research, UNAM, Ap. P. 34, Temixco 62580, Morelos, México Received 22 March 2004; received in revised form 25 April 2005; accepted 20 June 2005 Available online 31 August 2005

Abstract This article describes three future scenarios for the potential reduction of CO2 emissions and associated costs when biogenic ethanol blends and oxygenates are substituted for gasoline, and hybrid, flex fuel and fuel cell technologies are introduced in passenger automobiles (including pickups and sport-utility vehicles (SUVs)) in the densely populated Mexico City Metropolitan Area (MCMA), analyzed up to the year 2030. A reference (REF) scenario is constructed in which most automobiles are driven by internal combustion engines (ICE) fuelled by gasoline. In the first alternative scenario (ALT1), hybrid electric-ICE gasoline-fuelled cars are introduced in 2006. In the same year, ethyl tertiary butyl ether (ETBE) is introduced as a replacement for methyl tertiary butyl ether (MTBE) oxygenate for gasoline. In the second alternative scenario (ALT2), in addition to the changes introduced in ALT1, flex fuel ICE technology fuelled by E85 is introduced in 2008 and electric motor vehicles driven by direct ethanol fuel cells (DEFC) fuelled by E100 in 2013. A comparison between the reference and alternate scenarios shows that while the total number of vehicles is the same in each scenario, energy consumption decreases by 9% (ALT1) and 17% (ALT2), the total non-biogenic CO2 emissions drop by 15% (ALT1) and 34% (ALT2), CO2 mitigation cost is 140.14 $US1997/ton CO2 (ALT2), and ALT1 has savings and is considered a “no regrets” scenario. 䉷 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. Keywords: Ethanol; Fuel cells; Transport end use; Greenhouse gases; Alternative fuels; Hybrid vehicles; Flex fuel vehicles

1. Introduction As one of the countries that has signed and ratified the Kyoto protocol, Mexico has made reduction of greenhouse gases (GHG) emissions a national priority. In 2001, nonbiogenic carbon dioxide (CO2 ) from fossil fuel was the most abundant GHG in Mexico (75%), followed by methane (23%) and nitrous oxide (2%) [1], percentages are assumed to remain approximately the same at the present time. Except for the 5-year period from 1983 to 1987, transportation has led final energy consumption in Mexico since 1968. In 2001, the energy used for transportation (primarily

∗ Tel.: +52 55 5622 9704; fax: +52 55 5622 9791

E-mail address: [email protected].

fossil fuels) was 1600 PJ, representing 42% of all end use energy [2]. Within the transport sector, road transport is the main consumer (88%), burning 1408 PJ. Gasoline is the most common fuel, with passenger automobiles (including pickups and sport-utility vehicles (SUVs)) being the highest consumers, burning 400 PJ (25% of the transport sector). Mexico City and its surrounding 17 municipalities, called the Mexico City Metropolitan Area (MCMA), collectively constitute one of the largest urban centers in the world. With an estimated population of 20 million, the MCMA consumes 25% of country’s energy and is a significant contributor to GHG, accounting for 20% of the country’s total GHG emissions. Mexico City alone is one of the biggest contributors to GHG emissions in Latin America (2.1% of total

0360-3199/$30.00 䉷 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2005.06.024

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F. Manzini / International Journal of Hydrogen Energy 31 (2006) 327 – 335

regional emissions) [3]. The MCMA is a well-known, muchstudied area that urgently needs to address GHG management as a co-benefit of controlling other criteria pollutants (SOx , NOx , PM, CO). In the year 2000, 55% of the MCMA CO2 emissions originated in the transport sector, with 42% coming from gasoline automobiles and the remaining 13% from diesel vehicles and other transport modalities. Some GHG reduction actions have already been taken for diesel-fuelled public transportation [4], but none for gasoline automobiles. The purpose of this study is to fill that gap, formulating a prospective analysis of the MCMA’s energy for transport scenarios, applying alternative policies to gasoline passenger automobiles, which comprise the majority of road vehicles. Despite being an oil-producing country, Mexico imported 15% of its gasoline in 2003. This suggests that PEMEX, the national oil company, either lacks refining capacity or is incapable of refining oil at competitive prices. In addition, at current exploitation rates, the oil reserves are projected to last for only 12 years (a number that varies according to how the oil reservoirs are calculated). In any case, it is clear that the industry is approaching its limits [5]. In order to reduce global GHG emissions, local pollutant emissions and gasoline consumption, and to extend the oil depletion time, this paper studies the CO2 emissions and the economic consequences of the following measures applied to automobiles: (1) hybrid internal combustion (IC) gasoline–electric engines, (2) sugar cane ethanol as gasoline substitute in IC flex fuel engines and as part of ethyl tertiary butyl ether (ETBE) substituting methyl tertiary butyl ether (MTBE) oxygenate and (3) ethanol in fuel-cell-driven electric motors. Another objective of this paper is to determine how much the current ethanol production, the only renewable fuel considered in this study, must change in order to satisfy MCMA transport sector demand. 1.1. Hybrid IC gasoline–electric engines Hybrid vehicles have emerged as a transition technology between conventional internal combustion engines (ICEs) fuelled by fossil fuels and vehicles driven by electric motors. The hybrid design considered here combines an energy conversion system with an energy storage system involving an ICE, a battery array and an electric motor. Research is currently being conducted on increasing battery capacity while decreasing its weight and on improving ICE efficiency while lowering its emissions. A common hybrid vehicle design is series hybrid in which a battery array is charged with a small ICE and the propulsion to the wheels is supplied by an electric motor. Nevertheless, the advanced hybrid vehicle design adopted by most automakers is parallel hybrid, in which an ICE drives the vehicle and charges the battery array simultaneously. An electric motor propels the vehicle when moving at low speeds [6].

1.2. Ethanol One hundred percent ethanol (C2 H5 OH), otherwise known as ethyl alcohol (E100), has been used for many years in the transport sector to fuel modified ICEs. In various countries, up to 10% of ethanol has been mixed with gasoline as an oxygenate to create fuel formulations used by all vehicles [7]. Ethanol is also used to substitute MTBE, an oxygenate which, when mixed with gasoline, improves octane numbers and creates a cleaner burning fuel [8,9]. Bio-ethanol, or ethanol for simplicity, may be produced from sugar crops (cane, beets), starches from grain crops (corn, wheat), from cellulosic crops (grasses, trees) or cellulosic wastes (crop, municipal and mill residues or wastes) [10]. This bio-energy resource is useful for countries that want to reduce oil imports or conserve their domestic reserves, as is the case of Mexico, and can dedicate agricultural land to fuel-producing crops, rather than to food for human consumption. Brazil leads the world in the use of ethanol from sugarcane as a fuel, followed by USA with ethanol from corn. Brazil started its Proalcool program in 1975, increasing ethanol production and using it as an oxygenate in gasoline (up to 26%). In 1979, Brazil began to produce automobiles with modified ICE adapted to burn 100% hydrous ethanol. Production reached a peak in 1986 when 76% of all automobiles sold were ethanol fuelled. From 1979 to 2002, a total of 4.9 million alcohol automobiles were sold [11], tapering off to 3% of sales by the end of this period. In 2003, flexible fuel ICE automobiles appeared in the Brazilian market. These engines can burn any hydrous ethanol–gasoline blend using an electronic control that senses the fuel’s oxygen level and makes automatic adjustments of combustion parameters [12]. Flex fuel technology has almost replaced pure ethanol technology and has been well received by consumers. In 2004, 328 000 flex fuel automobiles were sold (22% of total) [13], a sales share that is expected to increase to 50% by 2005. Nearly every automaker offers or is planning to offer at least one model with flex fuel technology and the sale of pure ethanol vehicles has dropped almost to zero [14]. In Mexico, ethanol is produced primarily from sugarcane. Almost 50% of the 58 existing sugar mills currently have the infrastructure to produce ethanol [15]. In 1998, the total ethanol production was 162 million liters [16]. In recent years, the domestic sugar industry has plunged into a crisis due to the importation of fructose in large and increasing quantities [17]. In the state of Jalisco, a sugar industry group is promoting a short-term initiative to use 100% ethanol (E100) Swedish buses for public transport in Guadalajara, the second largest city in Mexico. The Jalisco proposal includes using 15% ethanol–gasoline blends (E15) for taxis and a 10% blend (E10) for private passenger cars [17].

F. Manzini / International Journal of Hydrogen Energy 31 (2006) 327 – 335

According to [15], in 1998, ethanol production costs were almost equal to the costs of gasoline production. The main shortcoming of the ethanol option is the limited supply if the fuel is made from corn or sugar cane [8]. Depending on the official price policy for fuels, the government could guarantee a subsidy to the ethanol producers as is done in Brazil. 1.3. Fuel cells Electric vehicles powered by fuel cells are considered by many to be the most promising technology for personal transportation in the near term [6]. When hydrogen fuelled, these vehicles have the potential to function at high efficiency, emitting only water vapor. In a fuel cell, hydrogen chemical energy is converted directly into electricity without combustion through hydrogen ion separation from electrons. In this way, electricity can flow continuously to the electric motor without being stored in batteries or connected to the grid through wires, as is the case for most electric vehicles. Mobile fuel cells need to operate within certain weight, size and temperature limits. Currently, the proton exchange membrane fuel cells (PEM-FC) are the best suited for transportation, being characterized by: (1) low operating temperature (between 80 and 100 ◦ C), (2) high current and energy density, (3) fast response, (4) relatively simple construction and operation, (5) quick ignition and shut off and (6) almost no maintenance requirements [6]. Hydrogen is a superior fuel-cell fuel, emitting practically no criteria pollutants (NOx , SOx , particles, HC) to the atmosphere. Nevertheless, the severe security and cost problems related to infrastructure for hydrogen station storage, distribution and storage for mobile application make it necessary to look for more convenient alternatives for fuel cells. One of the most promising possibilities is ethanol, which is both low in toxicity and readily available from biomass products. Research is being done in two types of PEM-FC fuelled by ethanol: reformed ethanol fuel cells (REFC) and direct ethanol fuel cells (DEFC). The latter have been commercialized for small-scale applications such as battery substitutes in cellular phones and CD players [18]. Chinese [19] and French [20] groups have done a great deal of DEFC research in recent years, focusing mainly on materials research for catalysts and electrodes. Steam reforming ethanol fuel cells (REFC) is the other alternative that uses ethanol as a hydrogen carrier to avoid the previously mentioned problems of storage and distribution of hydrogen [21,22]. This method employs ethanol to produce on-board hydrogen to use in a fuel cell automotive propulsion system. Reforming ethanol by reacting it with steam requires three water molecules for each molecule of ethanol: C2 H5 OH + 3H2 O → 2CO2 + 6H2 . Brown [21] assumes that ethanol reforming also produces little methane and a hydrogen-rich gas that has the following

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composition (in vol%): 62.6% H2 , 21.4% CO2 , 12.5% H2 O and 3.5% N2 . Another study discovered that there are also some acetaldehyde and acetic acid emissions in the oxidative steam reforming of ethanol [23], which means that these atmospheric pollutants have to be acquainted when searching for the best energy for transport options. In the 2005 issue of the Annual Energy Outlook [24], the USDOE/EIA assumes that automobiles driven by gasoline fuel cells will be commercially available by 2008. Given that ethanol is a lighter and simpler molecule than gasoline and very active, ongoing research is being done on ethanol fuel cells, this study assumes that either DEFC- or REFC-driven electric automobiles will be available in Mexico by 2013.

2. Scenario building A prospective approach to the future requires the creation of images or scenarios of the desired or probable future [25]. The main purpose of scenarios is to integrate specific analysis of tendencies, possible events and desirable situations in the context of a general future vision [26]. Before elaborating each scenario, common assumptions and their corresponding justifications must be made. The assumptions used in this study appear below. Ethanol price: the sum of current ethanol production costs for ethanol derived from honey-B-type in Mexico is 0.1736 $US1997/L according to Enríquez [15], assuring that ethanol represents a feasible alternative to sugar cane industry. Assuming that the ethanol retail price takes into account the infrastructure needed for a dehydration unit at the sugar mill, transportation and storage tanks at the refinery and a tax exemption incentive, according to Enríquez, the retail price for E100 should be 0.377 $US1997/L. This is the value adopted in the following economic analysis. ETBE is a good substitute for MTBE, a gasoline oxygenate which has been banned in some countries since it has been discovered to be an underwater pollutant. France and Spain use ETBE as an oxygenate and octane enhancer in gasoline up to 15% in volume (ETBE15) [27]. ETBE is obtained by synthesis of 48 vol% bio-ethanol and 52 vol% isobutylene, a byproduct from the oil-refining process [27]. The use of ETBE15 in Mexico offers a promising way to start the interaction between the sugar and oil industries, producing gasoline that has 6.75 vol% of bio-ethanol. Since PEMEX has recently acquired the technology to synthesize MTBE, switching to ETBE should not be difficult. Anhydrous ethanol from sugarcane can be used to produce ETBE in the same way that natural gas methanol produces MTBE [27]. Since Mexican gasoline already costs 10–25% more than in the USA, and supposedly contains MTBE, an increase in gasoline price with 15 vol% ETBE is not assumed. The following tables show input data and the starting conditions for all scenarios. Table 1 shows gasoline, E100, E85

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F. Manzini / International Journal of Hydrogen Energy 31 (2006) 327 – 335

Table 1 Fuel properties and characteristics

Molecular weight (kg/kmol) Octane number (RON) Energy content (MJ/kg) Non-biogenic CO2 emission factor (kg/GJ) Fuel price in 2000 [$US1997/L] AAGR in fuel price (%)

Gasoline E100

E85

ETBE15

111 97 44.8 68.6

55.8 100 29.5 10.3

109.7 100.2 42.1 63.9

46 109 26.7 0

0.481

0.390

0.396

0.481

3.1

1.7

1.9

3.1

and ETBE15 prices. Table 2 shows new car prices for ICE, HYB, FLEX and FUEL CELL technologies. Both contain a summary of the assumptions used in this study. This study assumes that the new technologies introduced gradually result in lower costs and greater efficiencies in the long term. On the other hand, ICE is a mature technology with very limited possibilities for cost-effective technological improvements. As long as the legislators do not raise fuel efficiency standards in USA, automakers are unlikely to invest in further technological improvements to increase its fuel efficiencies. The stock of vehicles in the MCMA is uncertain because official records do not include old cars rollover to/from other states. This study uses the Emissions Inventory 2000 [3] as the best available source for information regarding the total number of vehicles and their age distribution by year model, see Fig. 1. According to this source, the stock of automobiles on the road in MCMA (including SUVs and pickups) in January 2000, was 2.246 million. In the same year 336,947

automobiles were sold, making a year end total of 2.583 million automobiles [3], 99.8% of all automobiles were gasoline fuelled [3]. In the MCMA, diesel was used mostly by heavy trucks and buses. Table 1 shows CO2 emission factor data for each fuel from [28]. All new technologies will enter the market with a 0.2% of total sales in the first year. The AAGR varies according to the scenario. All three scenarios have the same number of vehicles in stock by year 2030, but their technology structure varies. Scenarios: a reference (REF) and two alternative (ALT1 and ALT2) scenarios are created in which a possible evolution of the MCMA automobile stock is shown up to the year 2030. The REF scenario is a business as usual (BAU) scenario in which all automobiles (including SUVs and pickups) run with gasoline ICE. There is no change in gasoline composition and its CO2 emission factor is 68.6 kg/GJ. Sales grow at an average 2.7% annually, a rate deduced from the growth of the vehicle stock for the last 10 years, extrapolated to 2030. In the ALT1 scenario, a new technology, parallel hybrid (HYB) gasoline ICE-electric motors, is available on the market by 2006. In the same year, gasoline sold in the MCMA contains ETBE15, produced with 48% of anhydrous bioethanol, as is currently done in France. In the ALT2 scenario, in addition to the hybrid automobiles added in the ALT1 scenario and the ETBE15 for gasoline, two more alternative technologies are introduced: flex fuel (FLEX) automobiles, fuelled by blending 85% ethanol 15% gasoline (E85) in the year 2008, as in the USA, and ethanol fuel cell (FUEL CELL) automobiles, fuelled by E100, by 2013. Table 2 summarizes the input data and assumptions made for each scenario.

Table 2 Technology and scenario parameters Scenario

REF

ALT1

ALT1

ALT2

ALT2

ALT2

ALT2

Automobile technologies Introduction year Sales share (introduction year) (%)

ICE —

ICE —

HYB 2006

HYB 2006

FLEX 2008

FUEL CELLS 2013

100

99.8

0.20

0.20

0.20

0.20

Sales share (2030) (%) Automobile price [24] ($US 1997) AAGR of price (%) Fuel efficiency-new vehicles [24] (km/L) AAGR of fuel efficiency (%) Fuel efficiency—stock vehicles N2000 and previous (km/L) Mileage (km/year)

100 15,680 0.3 10.2 0.0 7.9

78 15,680 0.3 10.2 0.0 7.9

22 20,327 −0.2 18.7 0.2 18.7

ICE — 99.8 (2006) 97.8 (2008) 89.0 (2013) 50 15,680 0.3 10.2 0.0 7.9

22 20,327 −0.2 18.7 0.2 18.7

18 16,424 0.2 13.0 0.2 13.0

10 49,436 −0.2 22.6 0.2 22.6

16,822

16,822

16,822

16,822

16,822

16,822

16,822

Base year values of mileage, fuel efficiency, prices, with its assumed annual average growing rates (AAGR), for reference (REF), alternative1 (ALT1) and alternative2 (ALT2) automobile scenarios in MCMA were obtained from [24].

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331

Age of existing cars in MCMA by 2000 14 Age of existing cars in 2000 12

Percentage %

10

8

6

4

2

0 1

2

3

4

5

6

7

8

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Number of years

Fig. 1. Age distribution of the number of automobiles in MCMA by the year 2000 [3].

3. Scenario simulation The scenarios are simulated using the long-range energy alternatives planning system (LEAP) version 2004.0036. Developed by the Stokholm Environment Institute—Boston/Tellus Institute, LEAP is a scenario-based, energy–environment modeling tool that has a computerized framework for the evaluation of national/regional energy planning policies [6]. LEAP has been used successfully for analyzing measures to mitigate global warming [7,8]. To model the energy requirements for transportation, LEAP uses a bottom-up, end-use-based approach called Demand Analysis. Energy demand analysis can be conducted using a variety of methodologies. For the transportation sector, LEAP offers a Transport Analysis methodology in which energy consumption (E) is calculated as the product of the number of vehicles (N), the annual average distance traveled by each vehicle (M) and its fuel economy (R), expressed in km/L: Et,y,v = Nt,y,v Mt,y,v Rt,y,v ,

The base year quantity of vehicles on the road is entered directly (N2000 = 2.246 million vehicles in January 2000), together with an age distribution profile of these automobiles obtained from [3], see Fig. 1. In the base year, automobile sales total S2000 = 337, 000. In the scenarios, future sales of vehicle projections are entered, as well as future levels of fuel economy (R) and the GHG emission factors of newly added vehicles. Tables 1 and 2 show fuel properties and transport analysis parameters and the assumed annual average growth rates (AAGR) for some parameters in the three scenarios. Assumptions regarding fuel efficiency improvements are based on EIA [24], except in the case of gasoline ICE for which no improvement is assumed. The stock of vehicles in subsequent years depends entirely on sales and a survival profile, calculated with the following equation [28]: Nt,y,v = St,v Ft,y−v

(1)

where E is the energy consumption expressed in liters of fuel, M is the mileage (i.e. annual distance traveled per vehicle in km), R is the fuel economy expressed in km/L, N is the stock (i.e. the number of vehicles existing in a particular year), t is the type of vehicle (i.e. the technology branch), y is the calendar year, v is the vintage (i.e. the model year).

Nt,y =

V


Ny,v,t ,

(2)

(3)

y=0

where S is the sales, the number of vehicles added in a particular year, F is the survival, the fraction of vehicles surviving after a number of years, V is the number of vintage years.

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4. Results and conclusions

Percentage %

SURVIVAL PROFILE K=-0.0236 100 90 80 70 60 50 40 30 20 10 0 0

5

10

15 Years

20

25

30

Fig. 2. Calculated survival profile of automobile stock in MCMA in year 2000 using Eq. (5).

A survival profile is used to describe the survival rates as vehicles age. A survival profile is defined as a percentage value relative to the value of the variable for a brand new device. Thus, the first year value for a survival profile is always 100% and has the following form: F (t) = F (t − 1)eKt ,

(4)

where K=

ln F (t) − ln(F (t − 1)) = −0.0236. t

(5)

For the MCMA in year 2000, the value of constant K is obtained from stock age distributions over 6 years [3] and substituted into the last equation, see Fig. 2. This methodology is designed to simulate increases in the vehicle stock related only to local MCMA sales. It does not include cars rolled over or bought elsewhere and introduced into the metropolitan area. Given the lack of accurate information regarding these “foreign” vehicles, the values obtained for energy and GHG emissions are underestimated. To make a cost assessment associated with cash flow, costs are calculated for each year between 2000 and 2030. These are expressed in present value for a given discount rate. The sum of present values in all the periods considered is called the net present value of the total cost [8,29]. Due to the complexity involved in the evaluation of all transport sector costs, expressed in $US 1997 dollars, only two important economic factors are considered: capital costs and fuel costs. Operation and maintenance costs are not considered because there is no information available for the new technologies. CO2 mitigation costs are calculated with LEAP’s nonbiogenic CO2 emissions results, dividing the difference in the net present values of reference minus ALT1 or ALT2 scenarios, divided by their differences in emissions.

Fig. 3 shows the net final energy demand by automobiles in the MCMA in each scenario. Since the number of automobiles (5 458 931) expected by 2030 is the same in all scenarios, the different energy paths are mainly due to the different technology efficiencies encountered in each scenario. Despite the fact that the base year of this study is 2000, all the graphs are plotted from an initial point that represents the year 2005 because all the scenarios are the same until that year. The reference scenario curve in Fig. 3 shows that ICE automobiles are the highest energy-consuming technology, almost doubling their energy consumption (up to 298 PJ) between 2005 and 2030. Scenario ALT1 reflects the high fuel efficiency of hybrid automobiles, which slowly increases from 18.7 in 2006 to 19.6 km/L in 2030. With 18% of stock share of HYB automobiles in 2030, energy consumption by 2030 is 9% less than the REF scenario. Scenario ALT2 has the lowest energy consumption, 17% less than the reference scenario, with a 50% sales share and 41% stock share of alternative automobiles by 2030. The 8% energy difference between ALT2 and ALT1 in 2030 is due mainly to the 8% stock share of FUEL CELL automobiles that have 22.6 km/L fuel efficiency. FLEX technology has a slightly higher fuel efficiency than gasoline ICE technology; therefore, FLEX technology participation in energy reduction is not as significant as in non-biogenic CO2 reduction. Fig. 4 shows non-biogenic CO2 emissions for each scenario. The reference scenario is the one with the highest emissions, 20.5 million tons by 2030, generated entirely by gasoline ICE automobiles, almost doubling the amount of 2005 emissions. The ALT1 scenario has 15% fewer CO2 emissions than the REF scenario, while ALT2 shows 34% less. As mentioned before, hybrid automobiles account for 9% reduction in energy; therefore, a 9% reduction in CO2 is also

310 Energy Demand [PJ]

332

290 270

REF ALT1 ALT2

250 230 210 190 170 150 2005

2010

2015 2020 Years

2025

2030

Fig. 3. Net final energy demand of automobiles in the MCMA in three scenarios.

22 emissions [million tonnes]

Non-Biogenic Carbon Dioxide

F. Manzini / International Journal of Hydrogen Energy 31 (2006) 327 – 335

20

REFERENCE ALT1 ALT2

18 16 14 12 10 2005

2010

2015

2020 Year

2025

2030

Ethanol Demand [million liters]

Fig. 4. Non-biogenic CO2 emissions of automobiles in the MCMA in three scenarios.

2,400 2,000

ALT1 ALT2

1,600 1,200 800 400 2005

2010

2015 2020 Years

2025

2030

Fig. 5. Future ethanol demand in MCMA in ALT1 and ALT2 scenarios.

due to this technology. The other 6% of the CO2 reductions are due to gasoline substitution for ETBE15, where bioethanol is a component in this blend with 67.5 ml/L. ALT2 scenario shows a gentle upward curve increasing only in 3 million tons of CO2 by 2030; the tendency of the curve shows that having 50% sales share of alternative biofuels and technologies will reach maximum emissions in the mid-2030s, if the sales share increases as a consequence of strong governmental actions, the point in which emissions begin to decay could arrive before 2030. Both alternative scenarios offer the long-term possibility of both increasing transportation energy use and decreasing CO2 emissions. Fig. 5 and Table 3 shows ethanol demand in ALT1 scenario due to 6.75 vol% ethanol as part of ETBE oxygenate in gasoline, ethanol production has to increase at an AAGR of 2.4% to reach 868 million liters (ML) by 2030. Ethanol demand in ALT2 scenario is almost four times the one in ALT1, due to the intensive use of ethanol by FLEX automobiles (E85) by 2008, and FUEL CELL cars by 2013 that use pure anhydrous ethanol, E100, either in DEFC or

333

REFC. Ethanol production has to increase at an AAGR of 6.8% to reach 2394 ML by 2030. Mexico produced 162 ML of ethanol in 1998 [16], with only half of its distilleries installed capacity working not at a full load [15]. Therefore, assuming that the current ethanol production and installed capacity in use remain the same as in 1998, to ask for an ethanol production increase of 305% (495 ML) in both alternative scenarios in 2006 seems exaggerated (see Fig. 5 and Table 3). Nevertheless, it might be possible in one or two more years. However, to increase ethanol production from 495 to 868 ML in ALT1 and 2394 ML in ALT2 scenario by 2030, would seem very plausible, considering the example given by Brazil that with its Proalcool Program increased their ethanol production from 172 in 1976 to 10839 ML in 1986 at an AAGR of 51% [30]. From the economic point of view, Table 3 shows that both ALT scenarios have higher capital costs compared to the REF scenario. This table shows the net present value (NPV) of the costs involved in each scenario calculated at a 10% discount rate. The differences between the ALT and REF scenarios, divided by its corresponding CO2 emissions reduction, shows that ALT2 scenario has a mitigation cost of 140 $US1997 per tonne of CO2 due mainly to the large capital cost involved in ALT2. In particular, fuel-cell cars are 2.5–3.1 times more expensive than ICE or HYB technologies [24], and its fuel savings are not large enough to give a low mitigation cost. On the contrary, ALT1 scenario shows net savings of 66 million $US1997 due to fuel cost savings. This result makes it a “no regrets” scenario, i.e. a scenario in which there is no additional cost. It has to be mentioned that in this work the scenarios were applied for Mexico City and its metropolitan area, but they are flexible enough to be applied to any other urban center or even the whole country, providing accurate age distribution data and average survival profile of the automobile stock. The results presented here are a first step towards cost evaluation of renewable fuels and alternative energy technologies for transport. More complete cost analysis is needed including, for example, the infrastructure costs for ethanol use and transformation to ETBE15 and blending into E85. Nevertheless, these preliminary results indicate that implementing the ALT scenarios described in this study can both extend the lifetime of Mexican oil reserves and reduce the emissions of CO2 , the most important GHG. The possible economic and ecological benefits mean that these scenarios deserve serious consideration. Acknowledgements The author wishes to thank Beatrice Briggs for her editorial assistance and Maria de Jesus Perez for technical assistance.

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Table 3 Results from LEAP simulation of transport scenarios up to 2030 in the MCMA. Number of automobiles in 2030 ICE [thousand] (%) HYB FLEX FUEL CELL Total number

REF

ALT1

ALT2

5459 (100%)

4472 (82%) 987 (18%)

5459 (100%)

5459 (100%)

3269 (59%) 987 (18%) 792 (15%) 411 (8%) 5459 (100%)

Net final energy consumed (PJ) (%)

298 (100%)

272 (91%)

248 (83%)

CO2 emissions [million tonnes] (%)

20.5 (100%)

17.4 (85%)

13.5 (66%)

CO2 reductions [million tonnes] (%)

—

3.0 (15%)

6.9 (34%)

Ethanol demand [million liters] 2006 2030 AAGR ethanol demand

— — —

495 868 2.4%

495 2394 6.8%

Costs [million $US1997], NPV, DR = 10% Capital cost Fuel cost Total cost

$ 68,761 $ 32,266 $ 101,027

$ 69,372 $ 31,589 $ 100,961

$ 71,172 $ 30,836 $ 102,008

Cost differences from REF [million $US1997], NPV, DR = 10% Capital cost difference Fuel cost difference Total cost difference

— — —

$ 611 $ −677 $ −66

$ 2411 $ −1430 $ 981

Mitigation cost [$US1997/tonne CO2 ]

—

$ −21.29

$ 140.14

Total number of automobiles by type of technology, net final energy consumed, CO2 emissions, mitigation costs and total costs calculating its net present values (NPV) with a 10% discount rate (DR).

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