AIR CARS
Gasoline
is already the fuel of the past. It might not seem that way as you fill up on
your way to work, but the petroleum used to make it is gradually running out.
It also pollutes air that's becoming increasingly unhealthy to breathe, and
people no longer want to pay the high prices that oil companies are charging
for it. Automobile manufacturers know all of this and have spent lots of time
and money to find and develop the fuel of the future.
The
search is on, but what will this fuel of the future be? Ready-made fuels like
petroleum are becoming more difficult to find and automobile manufacturers are
turning to greener energy sources like batteries. These batteries can be
charged with energy and placed in a car where that energy can be released. As
good as that idea might seem, some manufacturers think air could become an even
better energy source.
Air? At
first glance, the idea of running a car on air seems almost too good to be
true. If we can use air as fuel, why think about using anything else? Air is
all around us. Air never runs out. Air is nonpolluting. Best of all, air is
free.
Unfortunately,
air alone can't be used as a fuel. First, energy has to be stored in it by
squeezing the air tightly using a mechanical air compressor. Once the
compressed air is released, it expands. This expanding air can be used, for
example, to drive the pistons that power an engine. The idea of using
compressed air to power a vehicle isn't new: Early prototypes of an air-powered
vehicle go back to the middle of the 19th century, even before the invention of the
internal combustion engine.
At least
one manufacturer thinks that it's ready to sell air cars to the American
public. If all goes well, these cars could be available in the United States
relatively soon [source: Sullivan]. Over
the next few pages, we'll look at this technology, the reasons you may want to
use it -- and a few reasons you might not.
How
Compressed Air Can Fuel a Car
The laws of physics dictate that uncontained
gases will fill any given space. The easiest way to see this in action is to
inflate a balloon. The elastic skin of the balloon holds the air tightly
inside, but the moment you use a pin to create a hole in the balloon's surface,
the air expands outward with so much energy that the balloon explodes.
Compressing a gas into a small space is a way to store energy. When the gas
expands again, that energy is released to do work. That's the basic principle
behind what makes an air car go.
The first air cars will have air compressors
built into them. After a brisk drive, you'll be able to take the car home, put
it into the garage and plug in the compressor. The compressor will use air from
around the car to refill the compressed air tank. Unfortunately, this is a rather slow method of refueling and
will probably take up to two hours for a complete refill. If the idea of an air
car catches on, air refueling stations will become available at ordinary gas
stations, where the tank can be refilled much more rapidly with air that's
already been compressed. Filling your tank at the pump will probably take about
three minutes [source: Cornell].
The first air cars will almost certainly use
the Compressed Air Engine (CAE) developed by the French company, Motor
Development International (MDI). Air cars using this engine will have tanks
that will probably hold about 3,200 cubic feet (90.6 kiloliters) of compressed
air. The vehicle's accelerator operates a valve on its tank that allows air to
be released into a pipe and then into the engine, where the pressure of the air's expansion
will push against the pistons and turn the crankshaft. This will produce enough power for speeds of about 35
miles (56 kilometers) per hour. When the air car surpasses that speed, a motor will kick in to operate the in-car air
compressor so it can compress more air on the fly and provide extra power to
the engine. The air is also heated as it hits the engine, increasing its volume
to allow the car to move faster [source: Cornell].
Air Car
Advantages
One
major advantage of using compressed air to power a car's engine is that a pure
compressed air vehicle produces no pollution at the tailpipe. More
specifically, the compressed air cars we're likely to see in the near future
won't pollute at all until they reach speeds exceeding 35 miles per hour.
That's when the car's internal air compressor will kick in to achieve extra
speed. The motor that runs this air compressor will require fuel that'll
produce a small amount of air pollution. Some fuel (you can use eco-friendly
biofuels or fossil fuels) will also be used to heat the air as it emerges from
the tank. The newest compressed air engines also offer drivers the option of
using fossil fuels or biofuels to heat the air as it enters the engine.
Nonetheless, this technology represents a marked improvement over cars powered
by internal combustion engines that produce significant amounts of pollution at
any speed.
Air cars
are also designed to be lighter than conventional cars. The aluminum
construction of these vehicles will keep their weight under 2,000 pounds (907
kilograms), which is essential to making these vehicles fuel efficient and will
help them go
faster for
longer periods of time.
Another
advantage of air cars is that the fuel should be remarkably cheap, an important
consideration in this era of volatile gas
prices. Some estimates say that the cars will get the equivalent of
106 miles (171 kilometers) per gallon, although compressed air will probably
not be sold by the gallon. A more meaningful estimate is that it may take as
little as $2 worth of electricity to fill the compressed air tank, though
you'll also need gasoline to power the electric motor that compresses air while
driving [source: Cornell].
The
vehicles themselves also will be relatively cheap. Zero Pollution Motors, which
plans to release the first air cars in the United States and estimates a
sticker price of about $17,800, which would make these cars affordable to
budget-conscious American buyers [source: Max].
Air
Car Disadvantages
While an air car produces no pollution running
on already compressed air in its tank, pollution is nonetheless produced when
the air is compressed, both while the car is moving and while it's being
refueled. As we mentioned earlier, the vehicle's air compressor will probably
run ongasoline, and this gas will produce pollution when burned.
The air compressor at the gas station will
probably be powered byelectricity. The production of that electricity may or
may not pollute, depending on how that electricity is generated. For example,
coal-powered electricity could produce substantial amounts of pollution.
Cleaner sources of electricity, such as nuclear power or hydropower, will result in far less pollution. According to the Web site
Gas 2.0, an air car in the United States would create about .176 pounds of
carbon dioxide emissions per mile based on the average mix of electric power
sources during refueling. By comparison, a Toyota Prius Hybrid, which combines
a battery-powered electric
motor with an internal
combustion engine, generates about 0.34 pounds of carbon dioxide per mile. So,
while the air car is not quite pollution free, it still represents an
improvement over one of the most popular hybrid
cars on the market [source: Nuccitelli].
Distance could also become a disadvantage,
depending on your travel habits. The distance that an air car can cover without
refueling is crucial because very few filling stations will have compressed air
pumps available at first. If you only plan to use your air car for short
commutes -- distances less than 100 miles --will be fine. However, the
one-to-two hour wait for the car's built-in air compressor to compress a tank
full of air could become a problem on cross-country trips. Zero Pollution
Motors -- the American arm of MDI and the company likeliest to produce the
first air car for the U.S. market -- aims to have a car available soon able to
travel between 800 and 1,000 miles on one tank of air plus 8 gallons of gas
[source: Cornell].
Early prototypes, however, have traveled distances closer to 120 miles -- good
enough for your daily commute, but not quite adequate for longer trips [source: Motavalli].
What will happen if an air car suffers damage
in an accident? After all, compressed air tanks can be dangerous. To reduce
this danger, the air tanks are made of carbon fiber and are designed to crack,
rather than shatter, in a crash. This crack would allow the "fuel" to
escape harmlessly into the surrounding air. Manufacturers feared that air
escaping from one end of the tank could produce a rocket-like effect and propel the car on a jet of
air. The valve on the cars' fuel tanks has been placed on the side to minimize
this effect.
Despite these precautions, there is some concern
that the air cars' lightweight construction might make it difficult for them to
pass stringent American safety requirements and that this could hold up the
arrival of air cars in the U.S. marketplace. Other factors have come to the
forefront as well, and we'll learn about those next.
Air
Cars in the Marketplace
India's Tata Motors will likely produce
the first air car in the marketplace in the next few years. Tata Motors' air
car will also use the CAE engine. Although Tata announced in August 2008 that
they aren't quite ready to roll out their air cars for mass production, Zero
Pollution Motors still plans to produce a similar vehicle in the United States.
Known collectively as the FlowAIR, these cars will cost about $17,800. The
company, based in New Paltz, N.Y., says that it will start taking reservations
in mid-2009 for vehicle deliveries in 2010. The company plans to roll out
10,000 air cars in the first year of production [source: Max].
MDI also recently unveiled the joystick-driven AirPod, the newest addition to its air car arsenal.
Although the AirPod generates a top speed of only 43 mph, it's also extremely
light and generates zero emissions.
Major automobile makers are watching the air
car market with interest. If the first models catch on with consumers, they'll
likely develop their own air car models. At present, a few smaller companies
are planning to bring air cars to the market in the wake of the MDI-based
vehicles. These include:
·
K'Airmobiles -- French company
K'Air Energy has built prototypes of an air-fueled bicycle and light road
vehicle based on the K'air air compression engine [source: K'air]
·
Air Car Factories SA -- This Spanish company has an air car engine currently in
development. The company's owner is currently involved in a dispute with former
employer MDI over the rights to the technology [source: MDI].
Initially, the MDI cars will be the only air
vehicles on the market. However, MDI has reportedly licensed the technology to
manufacturers in a dozen different countries, so air cars should be available
around the world soon.
