on the inefficiency of internal combustion engines (ices) in road transport
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.”
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