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This teaching guide is designed to complement the 20-minute video, Crude Energy. Click here to request the video. Please note that video supplies are limited and may no longer be available. Mention
electric vehicles to most people and images of golf carts inevitably come to mind (or
maybe the golf cart’s beefier cousin–those beeping shuttles that sneak up behind
us on airport concourses). And, of course, there are battery-powered wheelchairs and
scooters that have become a boon for folks needing a little extra help in getting around. However,
as useful as they are, electric cars and carts have some considerable limitations.
Battery-powered cars usually can travel 70-80 miles per trip at best, keeping them in the
short-commute niche or limited to the above-mentioned golf course and airport. Recharge
time is also a significant factor. It can take hours to replenish a battery after only one
of those 80-mile trips.
HEVs–or
hybrid electric vehicles–are the newest innovations in the search for
cleaner-burning, more efficient transportation. By combining electric motors and gasoline
They’re
also a reality after years of drawing-board designs, experimental models and prototypes.
HEVs are actually showing up on showroom floors. And while there are some startup
companies set to produce HEVs, the first models are being built by mainline automobile
manufacturers, Honda, as well as General Motors, Ford and DaimlerChrysler. Increased Efficiency Regenerative Braking The combination of the two systems doesn’t mean you can drive until you run out of gas and use only the electric motor. The electric systems aren’t designed to power the car alone. In fact, many experts agree that purely electrical vehicles are a long way in the future. Because the energy density of electric batteries will never equal that of liquid or gaseous fuels such as gasoline or propane, these will need to be a part of future vehicles for some time to come. Efficiency by Design The
two principal types of drag that work on a car are aerodynamic and rolling resistances. By
reducing these forces, the car requires less power to propel it. Body design elements that
reduce aerodynamic drag include flush windows and recessed windshield wiper systems,
cab-forward design, tapered rear end and clean trailing edges, partially covered rear
wheels, smooth underbody that slopes up towards the rear, minimized body seams and a
smaller, flow-optimized front grill for air intake. (One proposed model from Ford will
even eliminate side-view mirrors, which cause drag by obstructing airflow around the body,
and replace them with video cameras and onboard monitors to display side views to the
driver. This system has the added benefit of eliminating that “blind spot”
we’ve all gotten a few thrills from.) Rolling resistance can be reduced by using
ultralight materials for the body and low rolling-resistance tires, wheel bearings and
brakes. By
using these techniques and materials, aerodynamic drag can be reduced by more than 40
percent and rolling resistance can be cut by more than 50 percent over conventional
models. And the aerodynamic design has an added benefit–aesthetics. The sleek lines
and futuristic appearance help with its commercial appeal, which will play a key role in
its public acceptance. Let’s face it–we all want to do good, but it
helps to look good in the process. And looks will help move the cars out of the showrooms,
a fact not lost on the carmakers. Economic Impact The
development of future HEVs is being encouraged by new government programs, including
partnering with private, public, nonprofit and educational concerns. The Department of
Energy (DOE) has an HEV program, begun in early 1993, that focuses on developing HEV
powertrains and internal components, but does not deal with the chassis, body,
aerodynamics and rolling resistance. Students Get Involved A
number of colleges and universities are also taking on the challenge of developing future
HEVs. Michigan Technical University and the University of Idaho, among others, have joined
in the Future Truck competition sponsored by General Motors, in which a stock GM truck is
given to the school to be converted to an HEV and is judged in several categories.
Virginia Tech and Cornell University have HEVTs (Hybrid Electric Vehicle Teams) which work
on developing new and different approaches to HEVs. So,
with all the incentives and talent at work, can the 100-mile-per-gallon HEV be very far in
the future? Or one with a voice-controlled radio and a rearview video camera instead of a
mirror? One thing is sure–we’ll all be breathing easier because of all the new
developments. Sources
Last Updated: 02/16/03 |
engines,
HEVs expand the range of electric cars while operating more efficiently (some models, such
as the Honda Insight, are advertised as getting 70 miles per gallon of gas). They’re
also cleaner and kinder to the environment. By using less gas, HEVs emit fewer pollutants.
While HEVs, as they’re currently designed, will never be zero-emission vehicles, the
first models can cut emissions by a third to a half and later models may cut emissions
even more.