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Back No.
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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 |
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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.
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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.
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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.
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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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