Dual-mode EVs and Infrastructure for Practical Long Distance Private Transit
You get into your EV, whose onboard batteries are fully charged from household power. It automatically retracts (fig. at right) its two power contacts from the power strips beneath it, in your garage. Or it may have been charging from solar power, from its PV (photovoltaics) on all of its top surfaces and windows.
Then, on battery power, you drive to a freeway that can supply in-transit power.
Your EV accelerates to ~60 mph on battery power, and reaches the electrified EV lane. When its automatic steering acquires lane center, it extends (see fig. at right) its two power contacts to power strips embedded on and parallel with the roadway beneath it. Now your EV gets most or all of its power (for propulsion and battery charging) from the power strips.
Or the power strips may be installed in a center divider (see fig. at left). Your EV would read this information from bar-code on the highway. So it would instead extend its two power contacts at its side, to make contact with the power strips. In either case, the power strips are recessed within insulation, to prevent inadvertent contact with people or animals on the freeway (who are at far greater risk of collision with conventional vehicles), or wayward conventional vehicles (which may be out of control or involved in accidents).
Automatic collision avoidance is another of your EV's features. It's driving ability is far better than the average human driver. And it greatly improves traffic flow. Now you are free to talk on your wireless phone, view on-screen maps of your destination, and even participate in a video-conference from your EV.
When your EV approaches your off-ramp, its lane-change indicator is self-activated, its power contacts are self-retracted (fig. at right), and it prompts you to exit the freeway. Now it's running on its onboard battery power. When you reach your destination, you may automatically connect with power strips to charge the EV batteries while parked, or charge them from its integral solar powered PV.
Your EV, with its integral PV and home garage power strips, automatically maintains optimum battery charge, with no action or chore required from you! You can forget about buying fuel at gas stations, or even needing to plug an outboard charger into the EV. And your EV will cost less to own and drive than today's car!
This is not science fiction! All elements of the technologies described here have been built, tested, and demonstrated. They all work, and very well. But they've not been integrated in a system that accommodates portal-to-portal personal transportation. That requires cooperation from road authorities.
Left: Illustration of dual-mode EVs on electrified freeway; which has PV solar panels mounted on center/safety divider and side/sound barriers, plus roadside PV covered shade for livestock or rest stop, and roadside windmills. Local stationary flywheel batteries (probably underground) provide UPS from stored power, for driving after dark, and whenever wind speed may not be high enough to provide adequate power on demand.
Through relatively short underground conduit feeder lines, these solar and wind sources, plus flywheel battery UPS, or possible grid power, feed electric lanes. Power strips need not be continuous (e.g., breaks shown in power strips above). In this mode, EVs are powered, via their extended contacts, by the power strips. This externally supplied power is used for propulsion, onboard battery charging, and EV accessories.
Grid power may be used. But ideal sources for in-transit EV power would be from solar and wind converters, especially on routes distant from power grids. They are rapidly becoming cost-competitive, proven technologies, that are being applied globally:
Above left: PV source that doubles as rest stop shade and shelter. They could also serve as shade and shelter for pasturing cattle, sheep, etc.
Above center: Highway sound barrier supports PV panels in Switzerland. This solar power, in proposed system, could give EVs essentially unlimited range on freeways that supply in-transit power.
Above right: Highway sound barrier above planted slope, with integrated PV panels, in Austria. An upcoming project in Holland will use PVs, installed on railway right-of-way, to power an entire electric rail system.
Left: CyberTran has successfully completed tests in Alameda County, California. Each vehicle is part of an electric public transportation system. Each has first class seating for 6 passengers, can be configured to seat 20 (or 32 in a pinch), is guided by computer control (no human driver aboard) and can travel at speeds up to 150 mph.
The vehicles' steel wheels ride on ultra-light rail. Rolling friction is lower than road vehicle tires. That's very important at lower speeds. But at its high speeds (like above 60 mph), aerodynamic drag exceeds rolling friction, so lower loss from steel-on-steel is not a significant factor. Power is supplied to them in-transit, via contact with power strips, so they don't need onboard batteries. But you can't drive them from your home and back, like privately owned EVs. Since they don't need a driver, expense for idle vehicles is not prohibitive. So they could accommodate more flexible schedules than today's large trains and buses. But passengers (and their belongings) would still need transportation to and from their boarding stations. So their popularity and ridership is yet a big unknown. Conversely, popularity of (and market demand for) personal, privately owned vehicles, is well established.
Future transportation, based upon shared use of electrified highways (like that for CyberTran), by public and privately owned electric vehicles, makes great sense. Our roads and highways are already shared by public and private vehicles, so a shared infrastructure is not a radical departure.
Clearly, the critical missing link, to applying grid, solar, and wind power, to the proposed EV highway for privately owned vehicles, are power strips on the highway -- and these have been working well, in one form or another, as recently demonstrated by CyberTran (above); and with many trams, trains, and amusement rides, for about a century!
Automatic servo steering, electronic collision avoidance, and power contact deployment on the proposed dual-mode privately owned EVs are straightforward technologies, that have been available and have been shown to work very well for at least the past 30 years. Despite the ability of this electronics to prevent collisions even with bad drivers, auto company lawyers advise against including these technologies, lest the manufacturer be held responsible for an accident. It takes great foresight and courage to get past that type of mind-set.
Owning and operating the proposed EVs will cost less than today's fuel burning vehicles, especially when dual-mode EVs are produced in large volume.
New US markets it will create are estimated at over $20 billion yearly for roadside flywheel batteries, $20 billion yearly for roadside PV panels, $10 billion yearly for roadside windmills, $5 billion yearly for power strips and feeders, and $100 billion yearly for dual-mode EVs.
Environmental benefits will be profound.
Obstacles to implementing this system are not
technical. They are institutional. When
we overcome that, we'll have some great engineering, appropriate sustainable
technology for a safer and far cleaner environment based on abundant and
renewable energy, plus vast new resulting global business and economic
Historical Perspective and Present Status
Electrochemical batteries powered the first electric road vehicles (EVs) over 100 years ago, introduced about the same time as fuel-burning cars, as alternatives to horse-drawn carriages. EVs were clean, elegant, and convenient, but had practically no infrastructure to facilitate battery charging, battery replacement was costly, and range was too short. Fuel-burning vehicles have greater range, plus ample refueling infrastructure (gas stations).
Rail vehicles were powered by fuel, or in-transit electric power where that was more practical and fuel emissions a problem. Amusement parks have operated rides with electric drive almost as long. Like rail vehicles, a practical infrastructure that provides power for amusement car propulsion, has been a key factor to their viability.
Over the past 2 decades, power electronics has been developed that enables ultra-efficient electric motor propulsion with regenerative braking. A type using brushless permanent-magnet motors, is described in Dick Fradella's US Patents 4085355 and 4520300 and pending flywheel power storage/regeneration patents. Motors and controllers are available from various developers, that can provide ideal EV propulsion. Fradella and others have developed modern on-board chargers compatible with ubiquitous 115vac or future dc inputs. But range limits of onboard power storage, and high battery maintenance/replacement cost, are the main obstacles to EV inter-city highway transportation.
Hybrid Electric/Fuel Vehicles & Fuel-cells
Hybrid EVs are being developed, that carry a fuel-burning generator onboard, along with batteries and electric propulsion. Their fuel-burning generator can be more efficient and pollute less than a conventional engine, but not significantly, and they certainly would cost even more than today's auto. US taxpayers gave more than $1 billion to the "big 3" auto makers, and $1.5 billion more is being given, to develop more efficient fuel-burning engines, hybrid EVs, and fuel-cells (that will generate electric power from fossil fuels, but without pistons). As with countless past public fund giveaway programs, to big political contributors, none of these government programs will solve our national pollution and fuel problems.
Fuel-burning vehicles carry what too often amounts to onboard incendiary bombs (in their fuel tanks). They pollute, kill, and worse. But transportation is a basic and critical need. Politicians have forced mandated "solutions" to air pollution, fuel shortages, a horrendous number of people killed and maimed by highway collisions, etc. on today's car drivers. It has placed an unacceptable financial burden on drivers, has not really solved targeted problems, and led to "road rage" crimes many attribute to driver frustration in traffic congestion, gridlock, car fumes, etc. For example, despite high costs most auto owners pay to reduce their auto's emissions, they continue to pollute; petroleum fuel supplies are still tenuous; and, despite mandated seat belts, air bags, and auto body re-design, about 40,000 to 50,000 people are still killed yearly in the US, in auto accidents (plus millions disabled yearly by serious auto injuries). Clearly, for the high financial costs paid, the mandated "solutions" are not working.
Drivers who use cell phones, who are involved in traffic accidents, are already law-suit targets, on grounds that phoning is a distraction that causes driver error. Accidents and their resulting litigation will increase intolerably, if more drivers begin to view on-screen maps or participate in video conferences, in today's cars.
Onboard Flywheels? We don't think so.
Flywheel promoters have been talking, for over 20 years, about onboard flywheels they can produce, that can power cars better than lead-acid batteries, and facilitate longer range. But nothing meaningful has been demonstrated by any of them:
A well-publicized project, supported by public funds, tried to power a car by a strictly mechanical flywheel in a vacuum container with gears, and a shaft brought out through a rotary seal. Unacceptable bearing and gear failures, vacuum loss, spin-down (mechanical equivalent of self-discharge) -- and explosion -- should have been foreseen by promoters or those who authorized funding, as several engineers outside these organizations had tried to explain to them physics they ignored.
The flywheel company's founder and that project's sponsors, who claimed the flywheel could not explode because its fiber-glass rim would disintegrate into fluff and powder, did not disclose results of a rim disintegration test past maximum rated speed.
More recently, several onboard flywheel battery projects have been funded. Their promoters say they can power EVs, but performance to date and reasonable engineering studies contradict that. Their predictions, about how magnetic bearings will solve their mechanical bearing failures, serious heating, and power loss are not based on sound engineering. Any serious analysis indicates that these projects will not result in safe or practical onboard EV power, for the following reasons:
At this time, despite major battery and fuel-cell
development projects, funded at taxpayer expense, lead-acid batteries remain
the only viable, cost-effective onboard power source for EVs.
Solar-powered Car Developments
Convergence of emerging technologies, such as declining-cost photovoltaics and power electronics, open up a new horizon for EVs and extra-vehicular infrastructure.
Left: Manta, a solar-powered EV developed and built by MIT students. Picture is link to team's website, which provides much useful information about their EV.
Engineering students at various universities build EVs powered by batteries, plus solar powered EVs with minimal battery packs, mainly to compete in races. Their accomplishments, with very modest budgets, using mostly donated parts, are indeed impressive. These student teams do not suggest that the EVs they build can be widely used as commuter cars or inter-city highway vehicles for more than two persons. But very valuable information is made available from their work, that can help to produce practical, low cost, and widely applicable EVs, that provide comprehensive solutions for current environmental and energy problems.
Right: One example, of a practical neighborhood EV, powered by
only 1 or 2 chemical batteries, photovoltaics on most surfaces that sunlight
can reach, and optional muscle power from its driver and even from a passenger. If your
health and fitness are priorities, EVs like this can help our environment,
provide local transportation at a small fraction of existing fuel-burning
automobile cost, give you independence from a tenuous petroleum supply, won't
need public charging stations, and motivate you to exercise so your busy schedule won't give you excuses
to skip workouts.
The image below shows all main features of this unique EV, described in more detail in my webpage
One of its 2 motor-wheels is shown in the illustration below, with a wheel cover removed to show the 8 springs that connect the motor to the wheel rim. Unlike almost all motors, this one spins about a non-rotating shaft. The motor is shown in red. The hollow (so 4 power conductors and 4 signal conductors can be brought out for connection to onboard motor control electronics) shaft within the motor is supported by a body support structure at each shaft side. Ball bearings in the motor serve also as wheel bearings. Unique new features such as this will reduce need for maintenance, parts and weight, and increase EV reliability and efficiency.
This EV's onboard electrical connections are shown in the diagram below. Its Ext. Pwr. contacts can plug into a 300watt garage wall outlet, and if electric highway infrastructure is one day permitted by government agencies, can access power from electric contact strips.
Proposed Dual-mode EVs and Infrastructure for them
In March 1976, the University of California at Berkeley's Institute for Transportation Engineering published a paper, "Electric Highway Vehicles... Technology Assessment of Future Intercity Transportation Systems" contributed by Dick Fradella. It described and analyzed a proposed EV technology and infrastructure, where EVs would carry batteries and an onboard charger, that could be supplied power in-transit, through conductive rolling contact on freeways.
It proposed 2 parallel recessed power strips, with 115v 60Hz or 100 to 170vdc across them. See schematic diagram at right. That would feed, through a full-wave rectifier, a charger (responsive to battery data and the rectified voltage waveform), that would draw unity power factor current with 5% or so total harmonic distortion, to charge at 95% efficiency, a 200vdc battery pack, while also supplying up to several kilowatts to a regenerative motor controller. EV battery charging, in any garage, can be from a standard 115v 60Hz outlet, or dc PV power, where available .
About 20 years ago, Fradella built a 300-watt demo version of a small system based upon this diagram. It demonstrates regenerative bi-directional speed control and proportional braking. Regenerative battery charging automatically results whenever the motor is decelerated. He has demonstrated it to countless manufacturers and researchers involved with EVs. Average life of motor-cycle batteries in the demo has been about 10 years. These batteries were guaranteed to last only 90 days.
Quantitative energy and environmental benefits were the paper's main thrust. It also touched on vehicle performance, electronic collision avoidance, and automatic steering... elements of a practical vehicular and extra-vehicular future EV system.
The paper was part of a broader study for the US DOT and DOE. It resulted in a follow-on demonstration contract sponsored by them, performed at Lawrence Berkeley Lab.
But DOT and DOE wanted power from the freeway to be supplied by inductive means, so "nobody would get electrocuted on the freeway." Fradella argued that the two conducting strips, of the electrified freeway (one shown in cross-section at right), would be so far apart, and accessible only by a small power probe, that any person or animal on the freeway, trying to be electrocuted, would be instead hit by a vehicle. He also argued that the huge, lossy, and very expensive, buried iron cores and copper primaries of an inductively powered system would radiate 60Hz magnetic fields with unknown physiological consequences. Also he argued that the core and secondary on the car would be big and heavy.
Inductive advocates prevailed. No demonstration of conductive coupling from roadway to EV was funded. The funded demonstration project verified that power could be coupled inductively from a roadway to a moving vehicle -- but we already should have known it would. It also probably verified that it is not an efficient, low-cost method, and makes no sense from a total system perspective. When completed, the entire in-transit power project was abandoned.
Unfortunately, conductive in-transit EV power was discarded along with inductive. Curiously, none who argued against a conductive in-transit power infrastructure disputed arguments in favor of it. Fradella's paper, and this page, analyze it from a total system perspective.
Its advantages (compared to inductive coupling) are:
With enough freeway routes that supply in-transit power, the proposed EV generally would carry only enough batteries for acceptable acceleration, regenerative braking, and speed on level to ascending/descending grades, and adequate range between electrified routes. Power contact strips on these routes can have discontinuities; where EVs would run for short distances on their onboard battery packs. EV range would essentially be limited only by the infrastructure provided for it.
Let's consider a representative EV for this model:
Gross vehicle weight with full load = 1500 pounds
Coefficient of rolling friction = 0.01 (15 pounds drag for 1500 pounds weight)
Aerodynamic drag coefficient = 0.1
Frontal area subject to aero drag = 20 square feet
Peak motor power = 20 kilowatts (about 26 horsepower)
Battery storage capacity = 6 kilowatt-hours (battery pack weight ~ 500 pounds)
Maximum battery power ~ 40 kilowatts (available for up to 30 second bursts)
EV may have 10 square meters integral PV that generates ~ 500 watts for ~ 5 hours per day. The PV's peak voltage may be about 220vdc, and its maximum current may be about 2.5 amps. It may be connected directly across the 200vdc battery pack terminals. Preferably, it will supply a small battery charger and power management system, that will enable discretionary loads like air conditioning when onboard batteries are fully charged.
Based on motor power, and a representative torque/speed
relation, wheel thrust at 20kw is:
651 pounds at EV speeds from 0 to 15 miles per hour
325 pounds at EV speeds from 15 to 30 mph
162 pounds at EV speeds from 30 to 60 mph.
These thrust computations are the electromechanical equivalent of a 3-speed transmission, which shifts to 2x wheel/motor speed ratio at 15 mph, and 4x at 30 mph. Fradella's motor does it by contact shifting. Motor/generator efficiency at maximum speed can be over 99%. Almost all loss occurs in stator conductors. Heat transfer is by conduction, with no air flow through the motor/generator. Induction motors with electronic controllers provide a similar thrust/speed curve. To analyze and predict EV performance with either motor type, Fradella wrote a computer program based on these equations:
Power to overcome rolling friction (watts)
(2 watts/mph.lb.)(Rolling friction coefficient)(Total pounds car weight)(mph car speed)
Power to overcome aerodynamic drag (watts)
(.005 watts/sq.ft. mph3)(drag coefficient)(sq.ft. frontal area)(mph car speed)3
Computed results, over a vehicle speed of 0 to 60 mph, are shown in the next two figures.
Left: A graph, of power needed to overcome the sum of rolling friction and aerodynamic drag, at speeds from 0 to 60 mph, for our representative EV.
At 60 mph, rolling friction consumes about 1.5-kw; aero drag about 2.5-kw; and they total about 4-kw.
Note that expected power of 500 watts, from the EV's PV surface, if the only power available, would support sustained cruising speed on a level grade to about 15 mph, without discharging the batteries.
Range at a cruising speed of 60 mph, from 6-kwh onboard batteries only, would be about 90 miles. During daylight hours, the installed PV can extend it to about 100 miles.
Parked in the sun, its PV can provide a full battery charge in 12 hours (in ~ 2 days of sunlight).
Left: A graph, of car speed vs. time to reach it, starting from zero mph. This EV would accelerate, on a level grade, to 60 mph in less than 20 seconds -- not a "hot-rod" but probably acceptable to many EV commuters and travelers.
Onboard batteries would supply the 20-kw acceleration power. In-transit power supplied by the roadway would be limited to about 5-kw, by the onboard battery charger.
While providing essentially unlimited range on electric lanes, external or integral PV power would normally keep onboard batteries fully charged. Deep discharge would be very rare. Also, fast charging would not be necessary.
Lead-acid batteries are capable of a limited number of complete charge and deep-discharge cycles. Battery life is enhanced when they are kept fully charged. Batteries left discharged over prolonged periods exhibit premature failures, even when not cycled. Fast charging, that results in high temperatures and gas formation, shortens battery life. Long-term tests, at frequent intervals, with Fradella's demo, indicate that normal battery service life of 10 years can be expected, in EVs operated in the modes described here.
Motor controller power electronics must handle 20 kilowatts, to provide acceptable acceleration, drawing usually short bursts of power above 5-kw from onboard batteries. To accelerate this EV from standstill to 60 mph, a 20-kw discharge, over 20 seconds, amounts to only 2% of a 6-kwh battery pack capacity. Sustained power of about 4-kw would normally be supplied by the main and solar chargers, while maintaining full float charge.
Main charger electronics need only sustain the 4-kw needed at 60 mph cruising speed, plus accessories and a bit more to reach and maintain full battery charge. When interior air conditioning is needed, at least 500 watts should be available from integral PV. Main charger electronics can be less than 25% of the regenerative motor controller's size, cost, and weight.
Regenerative braking would be automatically controlled by the accelerator pedal (actually a speed controller with soft braking response, in this case), cruise control, and brake pedals (having proportional braking control). Cruise control and automatic collision avoidance would not add weight, can cost relatively little, and would contribute much to driver comfort and safety. Hydraulic brakes would be retained as backup. Parking brakes would be conventional.
EV air-conditioning would have a brushless dc motor hermetically encased with the compressor it drives. Crystalline PV over most of the car body, insulation, and thin-film PV sandwiched in windows, would result in lower solar heat load and less heat loss in cold weather. Power steering would be electromechanical -- not hydraulic or pneumatic. Best of all, it would be automatically guided, needing only supervisory driver interaction.
In production quantities, after development and usual cost-reduction redesign, this EV could cost less than today's fuel-burning autos; much as an electric chain-saw costs less than one with a gasoline engine.
This EV's 6-kwh battery pack will cost about $1000 and last up to 10 years. So it's not a significant expense item. Battery cost would surely be offset by the EV's far lower fuel and maintenance expenses. Batteries that would weigh only a fraction of lead-acid, or provide more range, are presently very expensive.
Perhaps very best of all, for EV buyers, would be the low energy costs: If a toll-highway concessionaire charged the equivalent of 20 cents per kwh (about double usual utility rates), for EVs traveling 60 mph that consume 4-kw, energy for the EV would cost 1.33 cents per mile. If the EV has integral PV that produces 500 watts, then its energy costs 1.2 cents/mile.
A fuel-burning vehicle rated at 30 miles/gallon, with fuel costing $1.50/gallon, has fuel costs of about 5 cents per mile. Since this webpage was first written, a few years ago, fuel price has tripled. So fuel cost is now about 15 cents per mile.
EV weight, onboard batteries, power electronics, and energy costs, of course, would be scaled; depending on a particular EV (small ultra-light EV, family car, van, truck, bus, etc.).
Innovative transportation technologies, including dual-mode EVs, are described on an excellent website by Jerry Schneider.
Many readers have commented that rolling or sliding contacts would (as do antiquated street cars making contact with power cables and rails) have problems due to sparking contacts. These sparks and arcs are visible at night. They cause pitting and wear on the power cables and rails, and on the vehicle's power contacts.
The sparking, and its consequences, are due to the very high voltage incurred from intermittent contact with the vehicle's inductive load. No sparking would occur, with the circuit shown near the top of this page, because the full-wave rectifier on the vehicle would "free-wheel" when power contacts open.
Series wound brush commutated DC motors powered street cars before 1900
-- and still power them today! These motors have very high starting torque,
and need only 2 contacts: positive and negative. No semiconductor diodes
were available when these systems were installed. So sparking was tolerated.
However, simply adding the rectifier diodes shown for dual-mode EVs on
this page will eliminate sparking and its problems.
If you like the technology proposed on this page, or others, the only way we'll get it is to keep after our government representatives, until it becomes a high-visibility issue. Environmentally benign, safe EVs can be available at low cost, with attractive features, if institutional obstacles can be overcome. And the best way to start things rolling is to raise the issue at every opportunity. Thanks for your interest and action, and good luck!
If you have questions, comments or suggestions, email me: email@example.com
Updated November, 2013