EV/FCV/CNGV: Which fuel will redraw energy map of future?
Investigation into OEMs'arguments from Tokyo Motor Show
The concept cars at the Tokyo Motor Show 2013 unveiled a notable trend that the Electric Vehicles (EVs) were on a downhill course. Today's internal combustion engines (ICEs) have become highly fuel efficient and are still the most favored power source. The question is what will be the power source of the future vehicles, electricity, fuel cell, or compressed natural gas (CNG). This report shares some findings from a comparative study on the pros and cons of relevant technologies in relation to social needs. Incidentally, the recent progress in the shale gas drilling technology is completely redrawing the distribution map of natural resources. As a result, vehicles fueled by shale gas, Compressed Natural Gas Vehicles (CNGVs), are reaching both developed and emerging markets. Because of its good combustion characteristics and the affordability, natural gas may become the optimal fuel for green vehicles.
Tokyo Motor Show 2013:
|Japanese Maker part 1||Japanese Maker part 2||Japanese Maker Part 3|
|Suppliers Part 1||Suppliers Part 2||Non-Japanese OEMs|
Objective: To examine pros and cons of new energy sources
The market for the EVs is not growing as much as it was expected. The major reason is the limited battery capacity that leads to drawbacks such as poor handling, high prices and high maintenance costs of EVs. Coincidentally, Toyota and Honda announced that they would launch Fuel Cell Vehicles (FCVs) in 2015. Their FCVs will use a power-generating equipment to extend the driving range. However, the FCVs will cost more than the battery-powered EVs and their planned production falls far short of the market needs.
Another type of green vehicle, CNGV, is now shedding a light in the global stalemate of EVs. CNGVs run on methane-based natural gas which is commonly used in various industries because of many advantages. Additionally, the abundance of shale gas, brought about by the recent progress of drilling technologies, is enabling a revolutionary price cut and departure from reliance on oil-producing countries.
This report compares advantages and disadvantages of the EVs, FCVs, and CNGVs. It will also give an in-depth introduction of the CNGVs that are rarely talked about despite the significant advantages (in Japan).
Tokyo Motor Show 2013: concept cars' powertrains undergoing great change
The automobile market may be flooded with information on the Internet, but a motor show is as important as ever in giving insights into the directions of Japanese automakers. It is the place of bidirectional communications between automakers and users. One of the topics at the 43rd Tokyo Motor Show 2013 is the new energies being sought by automakers. A comparison with the Frankfurt Motor Show that was held just before the Tokyo Motor Show also gives interesting insights for the energy trends in Europe.
Automakers are no longer following an omnidirectional policy of development and commercialization regarding the future energy technologies. Unless they focus on a few directions, they will face a huge manpower and cost of development that is unbearable even for leading manufacturers. The table below shows a powertrain-based comparison of the Japanese automakers' concept cars exhibited at respective motor shows.
|Tokyo Motor Show||Frankfurt Motor Show|
|ICE (petrol) Vehicles: Hybrid Vehicles: EV: FCV: CNGV:||16 cars 7 cars 3 cars 2 cars 1 cars||( 3 cars) ( 3 cars) (10 cars) ( 2 cars) ( 0 cars)||12 cars 8 cars 2 cars 0 cars 4 cars|
(MarkLines' approximate figures covering passenger car concepts. Production cars and racing cars are excluded.)
The ICE-powered concept cars prevailed in 2013 as if they symbolized their comeback in respective markets. There has been a remarkable improvement in fuel economy that is now comparable with that of the hybrid vehicles. A notable trend seen among hybrid vehicles is the shift of attention from fuel economy to power performances (transitional addition of electric power to improve acceleration performance). Trends among vehicles driven by other power sources are summarized below:
* EV: The number of EVs at motor shows decreased drastically. In contrast to the ordinary-sized and shaped electric passenger cars that were on display at Tokyo Motor Show 2011, the three EVs exhibited at Tokyo Motor Show this year were ultra-micro EVs and an odd-shaped EV with an unusually small tread. This seems to suggest that electric vehicles are forced into a niche market.
(Left: Toyota's tandem i-ROAD, Center: Honda's MC-β two-seater that is only 2.5m long and 1.3m wide, Right: Nissan's Blade Glider three-seater with an unusually small front tread) * FCV: Toyota and Daihatsu were the only automakers that exhibited FCVs at the Tokyo Motor Show in 2011 and 2013. These companies are making continued efforts to develop FCVs toward a launch in the mid-2010s. But they face uncertainties that their FCVs may not have a competitive edge then over the vehicles driven by other power sources. The major promoter of FCVs is the industrial and governmental expectations toward the realization of a hydrogen society. In this regard, it appears that automakers are being used as a promoter of commercial production of hydrogen.
Toyota's FCV stems from the sports utility vehicle (SUV) that was launched for limited sale in 2008. The FCV is now incorporated in the passenger car packaging for sales starting in 2015. This is the result of improved technologies such as the doubling of the power output per size of FC stack, halving of the number of fuel tanks and cost reduction.
Honda's FCV was unveiled not in Tokyo but at the Los Angeles Motor Show at about the same time. Only a mockup vehicle was exhibited without any special technical breakthrough. The announced specifications were exactly the same as those of Toyota's FCV above (stack output density of 3kW/liter, total output over 1000 kW, driving range over 480km and hydrogen tank refilling time of 3 minutes). The unveiling of the FC car was no other than a mere declaration of intent .
While the two FCVs mentioned above assume hydrogen fuel, it deserves special attention that Daihatsu is considering a non-hydrogen fuel. Its choice is aimed at eliminating the platinum catalyst in the fuel cell and the high-pressure tank that are mandatory apparatus of a hydrogen fuel system. The non-hydrogen fuel system will be an ideal solution for mini vehicles in terms of physical installation and cost. Developing a non-hydrogen fuel FCV is expected to take longer than a hydrogen fuel counterpart. Therefore, launch in or around 2015 has not been planned.
Daihatsu's concept car dubbed the FCDeco DECK (Left: External view, Center: the FC under the seat, Right: cutaway model of the FC stack)
* CNGV: The Frankfurt Motor Show had all-new CNGVs exhibited by the two CNGV sales leaders, Fiat and Volkswagen Group, and Opel and Daimler. Because of the low interest in CNGV in Japan, an exhibit of CNGV was not expected in the motor show in Tokyo. Mazda, nevertheless, exhibited a prototype fitted with a CNG engine (details provided later).
Japanese automakers vary in their policies regarding energy sources. The differences may be understood more easily when the automakers are divided into four groups, with two in each group, as shown below:
|1.||Electric vehicle group with a leading edge in EV sales Nissan: EV usage extended to commercial vehicles and ultra-micro vehicles Mitsubishi: Electric drive in combination with engine drive (Plug-in Hybrid Vehicle - PHEV) to cover the drawback of EVs|
|2.||Global leaders in need of declaration of green vehicle policy, as they did not mass produce EVs Toyota: Plans announced to launch FCVs in 2015 Honda: Intent to launch FCVs in 2015, declared at the Los Angeles Motor Show|
|3.||Mini vehicle manufacturers with an immediate goal to improve fuel economy of ICEs Suzuki: Electrification is limited to engine-anchored hybrid systems Daihatsu: Trial production of non-hydrogen FCVs to stay away from the need for hydrogen refueling infrastructure|
|4.||Fun-to-drive group Subaru: EV launch plan was postponed to maintain strong sales of existing products Mazda: Sticking to ICEs with an eye on alternative fuels such as ethanol and CNG|
<Mazda 3 SKYACTIV CNG Concept>
As a global strategic car, the all-new Axela (known as the Mazda 3 in markets outside Japan) is the "multi-solution model" that may be fitted with different powertrains to meet local availability of fuel in different markets. In addition to gasoline, hybrid and diesel systems, Mazda has already announced technical trial to use ethanol (E85 with 85% ethanol fuel blend) and CNG. The company exhibited a CNGV prototype at the Tokyo Motor Show. The prototype has the following specifications although they may be modified at a later date (pending official certification) :
* Bi-fuel engine that can run both on gasoline and CNG - The basic petro-fuel powertrain is complemented by a gas fuel line that supplies CNG into the intake system - Fuel switching is done with the switch located near the AT selector lever - The injectors and the tank mentioned below will be supplied by Quantum Technologies, a U.S. corporation (assumption by MarkLines)
* Compressed natural gas is stored in a 75-liter gas container with 20MPa internal pressure. - Use of liquefied natural gas is not considered for sake of early market launch of the CNGV. (Use of a liquefied natural gas tank with cold storage temperature of up to 162 degrees Celsius below zero is being considered by long-haul truck makers, etc.)
|Upper left: Engine compartment with an addition of CNG system components Upper right: The entire car including the engine is based on the Axela Left: Engine compartment viewed from a lower angle showing two fuel lines.|
|Left: "GAS" button for selecting fuel type. The segmented display indicates the amount of CNG remaining in the tank.|
Worldwide spread of natural gas vehicles
CNG being chosen by Mazda is a fuel that is drawing a global attention because of the huge abundance that is often referred to as "the shale gas revolution." The vehicles powered by natural gas fuel have many advantages and are on the rise in various countries. Their present market penetration is listed below in terms of the CNGV population in top 13 countries and in leading automobile countries, Germany and Japan. The number of CNGVs in France, the U.K. and Spain is less than one fourth of Japan's.
|Country||CNGV Population||CNG stations|
|Total Vehicles||LD Vehicles||Total||Public||Private|
Source: NGVA Europe 2013.9.23
This worksheet suggests the following trends: * The CNGVs are on the rise in both advanced and emerging countries. * With the exceptions of Ukraine and Japan, small vehicles (light-duty vehicles) are playing a leading role in increasing the number of CNGVs in countries with a large CNGV population. * The ranking of the number of natural gas refueling stations somewhat differs from that of the CNGV population. However, it is safe to say that the countries with a large CNGV population generally have well-developed infrastructure. Germany is unique in that it has a large number of publicly-operated CNG stations considering its CNGV population.
Japan has a relatively large number of large CNGVs such as route buses and garbage trucks, operated by public authorities.
Three types of green vehicles - Well to wheel efficiency
EVs, FCVs and CNGVs are regarded as the preferred styles of mobility in the next generation. They are preferred from the standpoint of effective use of energy resources and from that of energy security, rather than because of their excellent dynamic performances as automobiles. Therefore, comparative analysis of their benefits must be based on an indicator that is comparable with the standpoint of preference. Otherwise, analysis will lead to a wrong judgment.
Comparison should start with a notion that fuel efficiency must be evaluated on a continuous basis from a well (natural resource) to wheels (driving). The life of natural gas fuel is illustrated below:
Prepared by MarkLines based on information published by Toyota Efficiency figures are taken from the following sources: * Black figures: Toyota research * Red figures: Reports by the Institute of Energy Economics, Japan submitted to the Ministry of Economy, Trade and Industry * Blue figures: Tokyo Electric Power Co., Inc. (an example of a combined cycle using waste heat from the main turbine)
The above table seems to suggest a seemingly conclusive remark that "it makes little difference to the total efficiency as long as the same natural resource is used." Other efficiency figures have been reported elsewhere and the above table happens to contain figures that are often cited by the Japanese government.
The process from energy manufacturing to filling in an onboard tank can vary significantly. Furthermore, the onboard efficiency can vary even more significantly depending on the engine, FC and motor characteristics and the range of operational loading. Therefore, the well-to-wheel efficiencies cannot be compared accurately within a range of several percent.
There are still several other points that need to be noted to avoid misunderstanding:
* EV's efficiency is not as high as asserted The onboard efficiencies of electrified vehicles are actually high (light pink column). However, they cannot be compared directly to the thermal efficiency of the engine. The electric energy being fed to the motor is no longer stored the same way gasoline fuel is. It is excited by the generator (and, therefore, cannot be stored in a stable condition the same way fuel is). Consequently, the power generation efficiency needs to be taken into consideration.
* Filling the high-pressure fuel tank requires far more energy than imaginable The latest FC tank has a rarely high pressure of 70MPa. Compressing the fuel for use on the FCV alone consumes 15% of the hydrogen energy itself. It is lost, rather than collected as a driving power, when the compressed fuel is decompressed on the FCV.
* Energy is also lost during storage Vaporized hydrogen leaks very easily (referred to as 'boiled off') and the daily leak can count for up to 4%. Electric energy cannot be stored in a stable state as fuel is, and is lost in the form of self-discharge of the battery. This loss cannot be calculated easily as it varies by the duration of storage. The loss is one of the factors that lower the total efficiency of the EVs and FCEVs.
Pros and cons of three types of green vehicles
As stated earlier, it is hard to discuss which type is more advantageous than the other in terms of efficiency within a range of several percent. The same holds true of tailpipe CO2 emission. What the society really demands of new energies is the increased security, rather than efficiencies or emissions, through a fundamental energy conversion. The advantages and disadvantages of the three types of green vehicles are presented below as seen from these points of views. 1. Sustainability of natural resources and energy security
EV: The sustainability level is the highest of all since electric power can be generated by various energies including natural energies and biomass. There are many options even in regions short of fossil energy.
FCV: The basic concept of a hydrogen society is the conversion of electric power into hydrogen in a storable state. Therefore, the advantage of electricity associated with the EV above also applies to the FCV. Although the flexibility is high in terms of the availability of energies, the efficiency of manufacturing hydrogen is low. Therefore, direct use of electricity is undeniably more desirable. On the other hand, power generation cannot be started and stopped easily depending on the type of electric power stations involved. This causes demand-and-supply gap which leads to surplus power. Furthermore, natural energy is available only intermittently and, therefore, is not suitable for grid merging. Manufacturing hydrogen can be meaningful if such surplus electricity can be utilized.
CNGV: Natural gas is not the only supply source of methane. It is buried underground in various forms and can also be manufactured by natural fermentation. Expectancy of stable supply of methane is high over a long period.
EV: The EV owners tend to install a private charging receptacle outlet at home. The increase in the EV population will lead to an increase in the number of charging points. Battery charging and paying the utility bill at home for passing-by EVs in front will become technically possible with the spread of Smart Meter (advanced device for recording electric energy consumption).
FCV: Special stations are required for refilling hydrogen fuel. The problem is whether hydrogen production is feasible as a business. From the standpoint of efficient use of energy, petroleum and natural gas should be used directly without reforming it to hydrogen. Supply of electric energy in excess of surplus electricity or natural energy cannot be expected from an economic standpoint (once electricity is generated, it should be used completely). A feasibility study must be conducted about commercial production of hydrogen based on the uneven, limited availability of electric energy.
CNGV: The number of CNG refueling stations is increasing. However, law prohibits an operator of a gasoline filling station to install a CNG station on the same premises a pressurized gas storage is classified as a dangerous facility in law. These artificial barriers must be removed for further spread of CNGVs. Another point that should be remembered is the city gas (natural gas with adjusted calorific value) that is available in every household. Filling a tank with city gas at home is technically possible using a small compressor. Such a portable compressor is actually sold in certain countries.
EV: Safety measures are required on vehicles fitted with lithium-ion battery. Theoretically speaking, it is prone to explosive autogenous ignition when the charge-and-discharge control fails completely or is internally short-circuited due to a physical deformation after collision. A direct cause of ignition is decomposition and combustion of an organic solvent but an electrolyte consisting of an inorganic solvent has not been realized.
FCV: The hydrogen tank is subjected to high pressure of 70MPa to store enough hydrogen fuel for an extended driving range. Unlike CNG or other petroleum fuels, hydrogen burns whether it is lean or rich (4 to 78% flammability limit). This leads to a fireball, a phenomenon of instantaneous explosion of hydrogen triggered by backfire to the fuel line or damage to the tank.
CNGV: There are no special risks of danger even in an automobile collision. In an event of a damaged tank, methane is scattered and lost without producing a large amount of combustible gas mixture since it is lighter than air (the gas mixture is hazardous if it fills up a closed compartment in a cabin).
As stated above, it is not easy to conduct a definite comparison of EVs, FCVs and CNGVs at present. Therefore, a robust judgment must be made based on theoretically undeniable advantages and disadvantages. The FCVs fitted with a high-pressure hydrogen tank does not seem to present much benefit at present other than the promotion of a hydrogen society. It also presents safety concerns and a well-balanced judgment is needed. Another factor to consider is the improved efficiencies of prime movers and installations whether onboard or ground.
Aside from all above, the low-priced CNG fuel must be most beneficial to heavy-duty trucks that are the largest consumers of the fuel. After Japanese automakers discontinued selling CNG-fueled heavy-duty trucks, some garage operators started CNG retrofitting. The low price of the CNG fuel will become even more notable after the start of shale gas imports in 2017. Truck manufacturers are considering developing new natural gas-fueled trucks with a tank capable of storing liquefied gas at 162 degrees Celsius below zero for extended driving range. CNG will continue to provide eye-catching news even in the future.
<Automotive Industry Portal MarkLines>