August 10, 2010


CO2 Emissions from the Japanese Transport Sector Already Decreasing

Keywords: Newsletter 

JFS Newsletter No.95 (July 2010)

Carbon dioxide (CO2) emissions have been increasing worldwide. Expanding motorization around the world is causing a steady increase in CO2 emissions from the global transport sector; in 2007 this sector accounted for about 23 percent of total world CO2 emissions (29 billion tons). The transport sector includes air, maritime, rail and road transport, but roughly 73 of emissions were generated from road transport.

In Japan, CO2 emissions from the transport sector accounted for about 19 percent of total CO2 emissions; in Japan's case about 90 percent of transport sector emissions were generated from road transport. While total worldwide CO2 emissions from the transport sector have been increasing, CO2 emissions from Japan's transport sector peaked in 2001 and have been on a downward trend ever since (See Figure 1). The sector's total CO2 emissions in 2001 amounted to 267 million tons, but by 2007 this decreased to 246 million tons, over-achieving the projected reduction target for 2010 (240 to 243 million tons). Japan, however, has been striving to further reduce these emissions. Here we describe how Japan's transport sector was able to shift from an upward to a downward trend and how it is pursuing further reduction now.

Figure 1: Actual & Targeted CO2 Emission Volumes in Japan's Transport Sector Transport_Sector_CO2_Emissions01_en.jpg

This positive trend was the result of efforts made in Japan's road transport sector to: (1) increase vehicle fuel efficiency, (2) improve traffic flow and promote eco-driving, and (3) reduce travel distances. If countermeasures had not been initiated in 1995, it is thought that CO2 emissions from Japan's transport sector would have steadily increased. Compared to a "no countermeasures" business-as-usual scenario, 36 million tons of CO2 emissions were avoided in 2007: 14 million tons through increased vehicle fuel efficiency, 13 million through improved traffic flow and eco-driving, and 9 million through reduced travel distances including modal shifts.

How Fuel Efficiency Improved

Although the 2010 target value for passenger car average fuel efficiency is 14.8 km per liter, the actual average (certified) fuel efficiency of new passenger cars on the market already reached 16.9 km per liter in 2008. Figure 2 illustrates the fuel-efficiency of Japanese cars; the figure shows actual and projected CO2 emissions from new passenger cars in selected countries/regions. Japanese automakers achieved their fuel efficiency targets through intensive mobilization of human and financial resources.

Figure 2: Projected CO2 Emissions for New Passenger Cars in Selected Countries/Regions


While exhaust gases could be controlled through a single improvement in catalyst technology, fuel efficiency can only be achieved through step-by-step technical advances. To improve engine efficiency, automakers improved thermal efficiency with adjustable mechanisms and reduced oil viscosity loss by using low-viscosity lubricating oil. They reduced vehicle weight by expanding the use of lightweight materials and designing better body structures.

Another important improvement was better power-train performance through an expanded number of transmission gears. Fuel efficiency has been greatly improved as a result of reduced aerodynamic drag through improved body configuration, and rolling resistance has been reduced by the use of low rolling-resistance tires: other factors including electric power steering, automatic idling prevention, and expanded use of hybrid cars have also contributed to fuel efficiency.

Japan's fuel efficiency standards are set under a maximum standard value system, the Top Runner Program. Under this system, targets are based on the values achieved by the most energy-efficient products on the current market. In setting Top Runner Standards for automobiles, the average fuel efficiency performance (FEP) of vehicles currently on the market are taken as the starting point and the average is raised to the level of top-runner vehicles. Subsequently, new target FEPs are determined by considering the potential progress of technology expected to be widely introduced in the near future. Thus, fuel efficiency standards have been raised higher and higher.

The fiscal 2015 fuel efficiency standard has been set at 18.6 kilometers per liter for passenger cars (10.15 mode), with provisions for increasing stringency. In the world, only Japan has fuel efficiency standards for each car category ranging from light to heavy motor vehicles. These standards are so strict that they cannot be achieved without a rapid pace of improvement in FEP over the next 10 years that matches the pace of improvement achieved over the last 10 years. Japan's automakers are making their utmost efforts in this field by promoting next-generation vehicles and other means, in order to meet these new standards.

FEPs achieved during actual driving are about 30 percent lower than the 10.15 mode FEPs listed in sales catalogs. The main possible reasons for this gap are: (1) losses due to inappropriate driving such as abrupt acceleration; (2) energy consumed for air conditioning and other electricity loads; (3) losses under cold weather conditions, including warming-up of the engine; and (4) losses caused by traffic congestion.

Better fuel efficiency can be attained not only through improvements achieved by automakers but also through efforts taken by drivers to drive in an eco-friendly manner, for example by avoiding abrupt acceleration and using air conditioners wisely. Traffic congestion could be eased by improvements in traffic flow. Carbon dioxide (CO2) emission reductions can be achieved if various measures are integrated to work organically.

Promoting Eco-Driving and Improving Traffic Flow

Although many drivers in the cargo distribution business have already adopted eco-driving habits because improving FEP lowers operating costs, most private passenger car drivers have not. In view of this, every auto manufacturer is introducing various types of onboard equipment, such as smart fuel gauges, to promote eco-driving.

Today, two-thirds of new private cars being sold have eco-driving promotion gauges that show real-time fuel efficiency or lights that come on when the car is being driven in an eco-friendly manner. It has been proven that correct recognition of fuel efficiency during driving and improved driving habits can upgrade the FEP by about 10 percent. If all passenger cars were being driven in an eco-friendly manner, millions tons of CO2 emissions would be reduced annually.

In order to promote eco-driving, the national government together with the relevant private sectors released 10 tips for eco-driving: (1) Accelerate gently; (2) Maintain a steady speed; (3) Slow down by taking your foot off the accelerator; (4) Limit use of the air conditioner; (5) Don't let your engine idle; (6) Don't warm up the engine before starting off; (7) Know your itinerary; (8) Check your tire pressure regularly; (9) Reduce the load being carried by your car; and (10) Respect parking regulations (as illegal parking can cause road congestion).

Improved traffic flow allows vehicles to increase their speed, which can improve fuel efficiency. On public roads in Tokyo's 23 wards, however, the average vehicle speed is only 17.9 km/h. If the average speed of traffic is raised from 20 to 40 km/h, CO2 emissions are reduced by 40 percent. Measures to improve traffic flow that can help reduce CO2 emissions include eliminating road congestion, modifying railway crossings, cracking down on illegal parking that can cause traffic congestion, and improving loop roads. In addition, other measures that use advanced transport technologies can also help, for example the Electronic Toll Collection (ETC) system, high-performance navigation systems, and sophisticated traffic signal controlling systems.

Learning from Japan's Experience

As stated earlier, the total distance traveled in the world is projected to increase by about 90 percent from the current level by 2030 as the number of vehicles grows. This means that global CO2 emissions from the transport sector are also expected to increase significantly. In this overall context, however, CO2 emissions from the transport sector in Japan have already peaked out. This fact and the factors behind Japan's success can be of great help to other countries in the world.

Based on the experience of Japan, the Japan Automobile Manufacturers Association, Inc. (JAMA) believes that a reduction in CO2 emissions can be achieved by taking a comprehensive approach that focuses on four different areas. It calls on automakers to raise the fuel efficiency of their vehicles, on the government to improve traffic flow, on fuel manufacturers to diversify their products, and on consumers to use their vehicles more efficiently, for example, through eco-driving and the use of low-emission vehicles.

Without this comprehensive approach, JAMA estimates that global CO2 emissions from vehicles will nearly double their current level by 2030. "If this approach is used, global CO2 emissions can be expected to reach their peak around 2025 and then start declining despite the increase in the number of vehicles," JAMA predicts. (See Figure 3)

Figure 3: CO2 Emissions in the Global Road Transport Sector Transport_Sector_CO2_Emissions03_en.jpg

To reduce CO2 emissions, it is important to establish fuel efficiency standards. Countries that lack fuel efficiency standards should first set standards for passenger cars, and then for trucks. In countries that have fuel efficiency standards, including the United States, European countries, Canada, Australia, South Korea, China, Taiwan and Japan, average fuel efficiency is increasing every year. However, many countries in the world still have no fuel efficiency standards. In these countries, fuel efficiency has not improved and CO2 emissions per kilometer traveled have not decreased.

It is also important to curb the increase of heavier vehicles by adopting a policy that promotes the use of lightweight cars. In recent years, there has been a tendency toward heavier vehicles in Europe and the United States. Only Japan is reversing this trend.

Another effective way is to boost the spread of low-emission vehicles by using tax incentives under a green taxation scheme. In Japan, lower tax rates apply to vehicles with high fuel efficiency and vehicles with low CO2 emissions. At the same time, higher tax rates are applied to vehicles that have been in use a certain number of years since their initial registration. This environmentally friendly tax system in Japan is actually showing results.

In developing countries, it is expected that people will increasingly flow into cities as populations increase. In such areas, road transportation policy, such as road improvement plans and the introduction of intelligent transportation systems (ITS) should be considered in the course of city planning earlier than has usually been the case so far.

We hope that every country and community will work out their own comprehensive measures which include raising fuel efficiency, improving road infrastructure, diversifying fuel sources, improving traffic flow and promoting eco-driving. We eagerly await the day when, as a result of these efforts, global CO2 emissions will reach their peak and start declining in the near future.

Written by Junko Edahiro

See also: Reports by JAMA on Japanese road transport sector