and the development of improved replacements - history and prospects. Recommended reading.
“One of the missing pieces at the time was an efficient and
lightweight energy-storage device that could instantaneously produce
high levels of power. Another gap in technology was a computer that
could manage multiple sources of energy efficiently and automatically.
It would have to deliver high power to the wheels when required and
also, when the car needed to be slowed, to transform the kinetic
energy of motion into electricity for charging the battery so this
energy could later be reused. Another element that was lacking was a
transmission system that could efficiently handle more than one power
plant.”
—
“For example, a hybrid car we constructed in 1997 named "Coulomb" (a
converted Mercury Sable sedan) has an engine with a displacement of
only 660 cubic centimeters, something one finds more typically
powering a modest-size motorcycle. Yet that diminutive engine can
produce 36 kilowatts, which is more than sufficient for sustained hill
climbing. Coulomb also contains an electric motor capable of putting
out 75 kilowatts peak power, which allows the car to accelerate from a
standstill to 60 miles per hour in only 9 seconds when used in
conjunction with its gasoline engine. With the car's 18-kilowatt-hour
pack of metal-hydride batteries, the motor can carry the car for 60
miles in all-electric mode.
“Advanced lithium-ion batteries now becoming available for automotive
use are smaller and lighter than the metal-hydride cells we have so
far employed, which will allow for lighter vehicles with the same
electric range or ones that can go even farther before they begin to
use gasoline. At the moment, the main roadblocks to lithium-ion cells
are higher cost, reduced longevity and concerns about safety, but some
battery makers claim to have solved these issues with their newest
designs. I look forward to testing some of the latest lithium-ion
batteries in one of the plug-in hybrids that I am now building with my
students. I fully expect that lithium-ion cells of one variety or
another will eventually replace metal-hydride batteries in hybrid
cars, offering a two- to threefold increase in energy storage for a
pack of a given weight, along with a greater ability to absorb energy
quickly during regenerative braking and, perhaps, with adequate
durability to last for 15 years and 150,000 miles.
“Charging time for the batteries in a plug-in hybrid is not nearly as
much of an issue as it is for a purely electric car, because the
engine can always provide propulsion. Thus the batteries can be
charged relatively slowly, which can be done quite efficiently from
nothing more elaborate than an ordinary household outlet. What is
more, because the power requirements for slow charging are quite
modest, the electricity doesn't necessarily have to come from the
electric grid - it can also be derived from rooftop photovoltaic
panels or from a small wind turbine.”
—
“As plug-in hybrids are manufactured in increasing numbers, they will
be paving the way to a society that bases its energy needs on
renewable sources. The various impediments to designing such vehicles
have been overcome one by one over the past three decades. The only
element clearly needing further progress is energy storage in
electrochemical batteries, and there is ample evidence that these
devices can soon be made in a way that satisfies the needs of the
automotive market. So I am confident that plug-in hybrids will allow
all of us to retain and indeed improve our comfortable lifestyles at a
lower cost and in a less disruptive manner than any transportation
alternative envisioned today.”
