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    EXPO 2005 AICHI

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transper_1pic.gif Rescuing the World
from Global Warming

Global warming is considered to be the gravest of the environmental problems the world is wrestling with. Resolving it will require nothing less than rectifying social and economic systems based on mass production, mass consumption, and mass waste disposal. One critical need is the development of new technology for suppressing the release of carbon dioxide and the other greenhouse gases responsible for the warming phenomenon. In this issue's Feature we report on the vanguard environmental technologies now emerging in the two fields of automobiles and energy generation in Aichi Prefecture, one of the world's most industrially developed areas. This is a probe into new possibilities arising from technologies for preventing climate change.

The ES3 concept car is an environment-friendly vehicle. It showcases Toyota's world-famous technologies in the areas of fuel efficiency, clean emissions, and recycling. Photos by Tomohiro Muda

The quest for the ultimate“eco-car”
An environment-friendly concept car
Next-generation air conditioners
Small-scale gas cogeneration

The quest for the ultimate “eco-car”

In this day of rapid change in technologies for improving the fuel efficiency and cleaning the exhaust of automobiles, such as hybrid cars and electric cars, people around the world are taking notice of the fuel cell car, billed as the ultimate “eco-car” destined to play the lead role among tomorrow’s low-pollution vehicles.

A fuel cell reverses the reaction in electrolysis, in which the application of an electric current to water splits it into hydrogen and oxygen. The fuel cell begins with hydrogen and oxygen and ends with electricity. Because the only other product of the chemical reaction is water, there is absolutely no release of carbon dioxide, nitrogen oxides, or sulfur oxides. The oxygen in the reaction comes from the air, so there is plenty of it. The hydrogen can be drawn from a variety of sources, so it presents less concern of depletion than fossil fuels like gasoline. Among the other merits of the fuel cell engine is that its overall energy efficiency far surpasses that of the gasoline engine.

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The FCHV-4 has a high-pressure storage tank in which hydrogen for the fuel cell stack is maintained at a pressure of 250 atmospheres. The car, which recovers energy from braking and uses it for battery recharging, has achieved test results of speeds exceeding 150 kilometers per hour and a cruising range exceeding 250 kilometers. (Photos courtesy of Toyota Motor Corp.)
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Toyota Motor Corp., based in Toyota City in central Japan, was the first automaker in the world to market a low-pollution hybrid vehicle, the Prius, which has a gasoline engine and an electric motor. In 1992, in the hopes of suppressing harmful emissions down to zero, it initiated research into fuel cell vehicles, and in 2001, after much R&D work and many refinements, it unveiled two fuel cell hybrid vehicle prototypes, the FCHV-4 and FCHV-5. While both use secondary batteries to assist their fuel cells, which are the main power source, they differ in the method utilized for supplying hydrogen. After testing the FCHV-4 for over a year on roads in Japan and the United States, Toyota has announced that it has refined the car to the point where it is ready to begin limited sales in Japan and the United States around the end of this year. This will mark the world’s first sale of fuel cell vehicles.

One might hope that this development portended the imminent arrival of the age of the fuel cell car, but Masanari Fukuda, manager of Toyota’s Corporate Citizenship Department, cautions that much remains to be done: “Many hurdles must be cleared before full-scale marketing can start. These limited sales amount merely to test marketing aimed at commercialization in the future.”

Just one of the hurdles to a practical vehicle involves the way the hydrogen is supplied. One way is to carry hydrogen within the vehicle for its direct supply. Another is to fill the gas tank with a hydrocarbon fuel like gasoline or methanol, which is converted into hydrogen via an on-board reformer. The FCHV-4, which carries hydrogen in a high-pressure storage tank, employs the former method, while the FCHV-5, which uses an on-board reformer to make hydrogen from a “clean hydrocarbon fuel,” or CHF, makes use of the latter.

As Fukuda comments, “The direct supply of hydrogen to cars would obviously necessitate new infrastructure, since gas stations aren’t equipped for that. And if hydrocarbon fuels are pumped into cars, new technologies will have to be devised to upgrade on-board systems. Toyota will be addressing such issues in cooperation with public agencies, the energy industry, and others. It will become increasingly important for us to think about building a social system suited to the realization of the fuel cell car.”

There are thus some major obstacles still to be cleared away before fuel cell vehicles can hit the streets in large numbers. Without doubt, though, Toyota has made a promising start on the quest for the ultimate eco-car.

An environment-friendly concept car

At the Frankfurt Motor Show held in September 2001, Toyota unveiled a concept car showcasing the various environmental technologies it is proud of. This is the ES3, an advanced prototype of a four-passenger car powered by a diesel engine. Standing for “eco spirit cubic,” the ES3 was designed with three goals in mind: to achieve the world’s best fuel consumption, to achieve the world’s cleanest exhaust emissions, and to develop future technologies for recycling. The car shows what one can hope the automobile of the twenty-first-century will be.

What strikes one first about the ES3 is its ability to travel 100 kilometers on only 2.7 liters of diesel fuel. The use of an aluminum body and plastic panels kept the weight down to 700 kilograms, and relentless pursuit of aerodynamic design minimized the drag coefficient. Such features enable the car to be big enough to fit four adults comfortably even while achieving astonishing fuel mileage, making it suitable for practical use.

The car has a 1.4-liter, direct injection, turbo diesel engine, and it combines this with a continuously variable transmission, considerably reducing fuel costs. Two technologies refined for Toyota’s hybrid vehicles were also incorporated to enhance efficiency: stop and go powertrain management, which turns the engine off when the vehicle is stationary, and regenerative braking, which recaptures energy otherwise wasted during braking.

Conventional diesel engines are notorious for the fumes they release, but the ES3 significantly curbs emissions of particulates and nitrogen oxides by means of a new technology Toyota has developed, the DPNR (Diesel Particulate-NOx Reduction) system. The load the ES3 would impose on the environment at the time of its disposal has also been lightened by means of recycling technology. Of note in this respect is the use of an improved TSOP (Toyota Super Olefin Polymer), which is easily recycled, in a number of components, while biodegradable plastics made from such plants as sweet potatoes are used in others.

Though the ES3 embodies some impressive environmental technologies, Kazuhiko Miyadera, the person in charge of its developments, reminds us that it is purely a concept car “developed for the express purpose of testing and research.” There is no plan for putting it on sale, he says. But he adds that “we can expect to see many elements of the technology developed for it incorporated in a variety of ways in forthcoming mass-produced cars.” When contemplating the future of the eco-car, we should keep in mind this offering from Toyota, designed as it was with a view to protecting the global environment.

Next-generation air conditioners

Even as innovation for environment-friendly cars moves rapidly forward, progress is also being made in the technology for the air conditioners that practically all cars sold in Japan come equipped with these days. The work on this front is part of the endeavor to prevent global warming, and Denso Corp., the world’s top maker of air conditioners based in Kariya City, is one of the leaders in the research.

“Today’s car air conditioners,” comments Manager Yasushi Yamanaka of the firm’s Air-Conditioning R&D Department One, “mainly use the hydrofluorocarbon HFC-134a as a replacement for chlorofluorocarbons. This refrigerant does not destroy ozone, but it is nonetheless a strong greenhouse gas. If it gets released into the atmos-phere, it can significantly aggravate global warming.”

A test car equipped with a carbon dioxide air conditioner. Carbon dioxide is fed into the unit with a special servicing device.
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In a bid to minimize the warming effect of this coolant’s use, Denso thus far has aimed at upgrading the design of air conditioners to reduce the amount of coolant consumption and improving hose joints to eliminate leakage. Today, though, it is channeling even more effort into developing air conditioners that run on natural refrigerants with only a small greenhouse effect, such as carbon dioxide or hydrocarbons. Since 1995 it has been devoting special attention to carbon dioxide, which is being hailed around the world as the ideal refrigerant for the next generation of air conditioners. Its use in place of HFC-134a holds the promise of dramatically reducing any influence on the climate. In 2001 Denso came out with the world’s first trial product capable of installation in cars, and it is now being tested in Toyota’s fuel cell hybrid vehicles.

The next stage is to resolve one by one an assortment of problems holding back the use of this technology in conventional cars. Techniques for mass-producing carbon dioxide air conditioners must be devised, and issues of safety and reliability must be addressed. Yamanaka is optimistic: “We expect to make the system fully applicable in ordinary cars within a few years.” It thus seems likely that a “dream air conditioner” employing a next-generation cooling system will join the war on global warming in the not-too-distant future.

Small-scale gas cogeneration

Global warming is on the one hand an environmental issue, since it threatens to make the climate worse in many places, but it is also an energy issue in that most of the efforts to address it involve conserving energy or shifting to clean energy sources. A number of new electricity sources can be counted on to curb the warming process. Solar power and wind power, which are already in fairly wide use, are prime examples. But another source that is receiving considerable attention these days is cogeneration powered by natural gas, since it offers an effective way to reduce emissions of carbon dioxide.

Cogeneration refers to the generation of two or more forms of energy, such as electricity and heat, from a single energy source. In the case of gas cogeneration, natural gas is used to run gas engines or turbines for generating electricity, and the waste heat given off in the process can be put to a number of uses, such as heating, cooling, and hot water supply. Such systems achieve high efficiency in energy conversion.

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The home of a Toho Gas employee was chosen for testing this gas cogeneration unit for household use. Sales of the system are scheduled to start in March 2003.
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Tatsunobu Amemiya is the manager of the Urban Energy R&D Department of Toho Gas Co., Ltd., a Nagoya-based firm with a solid track record in the development and deployment of gas cogeneration systems. “The chief merit of gas cogeneration,” he argues, “is the big contribution it makes to energy conservation.” He continues, “In conventional thermal power generation, no more than some 38% of the primary energy supply ends up being utilized. This is because during electricity generation most of the heat released is simply discarded, and during transmission a lot of electricity leaks away. When gas cogeneration is employed, by contrast, there is not that much transmission loss, since electricity can be generated at the place where it is consumed, and profitable uses can be found for much of the released heat that ordinarily goes to waste. As a result, remarkably high energy utilization rates in the 70 %–80 % range can be obtained. It has been calculated that the volume of carbon dioxide emissions can be cut by 24 % when the electricity source is switched from thermal power plants to a gas cogeneration system.”

These systems come in two basic types. Gas engines are suited to relatively small-scale supply, from 6 kilowatts to 5,500 kilowatts. Gas turbines provide a larger supply, starting from 28 kilowatts and extending up to tens of thousands of kilowatts. In addition, work is now in progress on systems of fuel cell cogeneration, which generate electricity even more efficiently.

Initially the market for gas cogeneration centered on industrial plants making use of large-scale systems delivering several thousand kilowatts of electricity. The scope of the market broadened significantly, though, when in 1998 Toho Gas commercialized a small-scale gas engine system with a 9.8-kilowatt capacity and when it later introduced a gas microturbine system with a 28-kilowatt capacity. Operators of restaurants, supermarkets, and medical and welfare facilities were intrigued by the ability of these systems to supply hot water and provide air conditioning, and they joined the ranks of the buyers.

“We can expect the market to continue to widen,” Amemiya predicts, “as such customers as convenience stores, fast-food outlets, and fitness centers show up. But the ultimate market is the household sector—the home of the ordinary family.” In this regard, Toho Gas has already developed the world’s smallest gas cogenerator. Intended for use in homes, it delivers 1 kilowatt of electricity. While practical testing is now underway in ordinary homes, widespread use of the system still lies some distance in the future because of further work needed to bring down the price, among other tasks. It nonetheless is clear that vanguard energy systems designed to protect the earth from climate change will one day advance into the domain of family life. (Masaki Yamada)

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