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Bright Idea: The 100-MPG Delivery Van

Posted May 04, 2009 9:40 AM by CarDomain

Bright Automotive unveiled their new 100 mpg delivery van on Earth Day. From the article in Wired:

"It's got lots of room and a 2,000-pound payload. With a 50-mile, all-electric range, the Idea sounds like a great urban delivery rig. It has a mixed hybrid drivetrain under the hood. A gasoline engine delivers the front wheels when needed (when the battery gets low) and helps recharge the battery pack as it approaches depletion. An electric motor drives the rear wheels."

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#1

Re: Bright Idea: The 100-MPG Delivery Van

05/04/2009 11:54 PM

Interesting. Generally, the more stop-and-go operation (traffic, delivery, etc.) the more practical a hybrid becomes. You still have to do the math, though- the difference in cost between a conventional and hybrid vehicle will buy a LOT of fuel and brake pads. Even with gasoline at $3 per gallon, the payback period for a hybrid was often longer than the vehicle's useful economic life, and definitely longer than the battery life. If it's important to your company to maintain a "green" image, then go for it- but charge the cost difference to your PR budget.

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#3
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Re: Bright Idea: The 100-MPG Delivery Van

05/10/2009 1:07 AM

On the topic of doing the math.

100 mpg??? At what speed? How can this be. When I look at these claims they all look like over unity claims to me; let me explain.

On a flat surface the total work done by the drive train traveling 1 mile at cruise would equal the sum of the drag and friction forces times the displacement. IE Work = force x displacement

Most of the work done at cruise is going to be against aerodynamic drag - but wait !!! Aerodynamic drag increases directly as the aerodynamic cross-section and the SQUARE of the velocity. So this 100 mpg term is really quite meaningless unless I know not only the average velocity but also the other variables to include the net change in gravitational potential the vehicle is operated through.

Do the math based on the efficiency of the prime mover and the combustion energy of the fuel source. Since mpg is most associated with gasoline or diesel fuel then compare the combustion energy of one gallon of the fuel to that of the drag X displacement of the vehicle; and remember, because of the low efficiencies of heat engines the actual work will be somewhere less than 30 percent of the combustion energy of the fuel. In the case of the vehicle being charged by the electrical grid that efficiency will fall well below 20 percent. I think what you will find is that somebody has cooked the numbers.

Having said ALL of that; hybrid technology is a great idea. Remember that remark about the low efficiency of internal combustion engines (ICE)? Thats why regenerative braking makes so much sense. It seems reasonable that a ICE operating at 20 percent efficiency would require 5 units of combustion energy for 1 unit of mechanical energy produced. This means that for each unit of kinetic energy converted to stored energy and reused it saves 5 units of combustion energy.

The engineers will eventually tumble to the three fundamental efficiencies of hybrid technology and the economy of scaled production will drive down the cost of manufacturing.

Here is a little thing I first published on bestsyndication.com but can no longer be accessed because of malicious redirection. It may help in understanding -

The Three Fundamental Efficiencies of Hybrid Technology.

In transportation based hybrid power production, how the power is produced takes a back seat to how the power is processed. The three fundamental efficiencies of refined wheeled vehicle hybrid power processes are "Prime Mover Power Averaging", "Regenerative Braking," and "Peaking Power."

Power Averaging:

"Power Averaging", also referred to as "load averaging or load leveling", allows maximum power output of the prime mover to be reduced to that slightly greater than that needed to cruise on level terrain at maximum sustained velocity. This reduces prime mover (engine) mass and volume; offsetting the mass and volume of the required temporary storage device.

Peak process demand in an automobile or other wheeled vehicle occurs during acceleration and grading (climbing hills). Existing hybrid systems translate this demand real time to the prime mover. In the next generation of hybrid automobiles the prime mover will operate at a near constant output from start up to shut down. The prime mover will feed near constant power into a temporary storage device (battery, capacitor, flywheel, or hydraulic accumulator) and the variable real time demand power will be pulled off that storage device. This will allow for a very significant reduction in maximum power requirements of the prime mover, optimize prime mover power production, and allow the introduction of prime movers not well suited to rapidly variable demand.

With Power Averaging as a primary efficiency of hybrid technology, the fueling algorithm of the next generation of hybrid automobiles will be a bit more complex than a simple iterative program. The coming generations of automotive control computers will "remember" power use based on both "routes" and "habits", calculate average demand, and de-couple operator control from prime mover demand with the ability to handle unanticipated variability of daily commuting. How that will be accomplished is beautiful in its simplicity.

The reciprocating engine dominates automotive technology because of its ability to respond rapidly through a broad power range. Power Averaging will allow the adaptation of prime movers that, although may not respond rapidly to power variation, operate at very high efficiently when operated at a near constant output. Given modern materials, the economics of scaled production, and the primary fundamental hybrid efficiency of Power Averaging, the choice of prime mover technology will be expanded to include Turbine and Sterling technology as well as existing Clean Diesel Combustion,conventional gasoline powered reciprocating engines, fuel cells, or any other primary power technology.

Regenerative Braking:

Regenerative Braking can be described as the recovery of kinetic energy (energy of the vehicle mass moving) to stored energy through numerous regenerative braking methods. Prior to regenerative capable hybrids, highway driving was more fuel-efficient than city driving even though aerodynamic losses of high speed highway driving far exceeded that of low speed driving in stop and go traffic.

In stop and go driving the energy conversion process can be described as the conversion of chemical potential energy of the fuel source by the prime mover, to kinetic energy of moving vehicle mass, to friction braking heat loss. The energy loss is directly proportional to the number of stop and go cycles. The multiple cycles of this conversion loss in stop and go driving can greatly exceed that of aerodynamic drag in constant state highway driving. Existing hybrid systems now regenerate significant amounts of energy lost during braking and this fundamental efficiency is expected to radically improve as the power and energy density of the temporary storage devices continue to improve.

Peaking Power:

"Peaking Power," when described as a fundamental efficiency of hybrid technology, refers to short term/ high power supply of energy to the power train from a temporary storage device during the peak demand periods of acceleration and grading (climbing hills.) This allows the drive train to be supplied power at rates much higher than the maximum power rating of the prime mover for short periods. The prime mover must still be capable of producing a sustained power slightly greater than the power required to cruise at maximum sustained velocity on level grade, but the cruising (or average) demand is much less than peak demand.

The coming generations of hybrid vehicles will have the operator controlled capability to rapidly accelerate to velocities significantly greater than maximum sustained velocity. This will be accomplished by summing the energy available in storage with prime mover output. As the storage device discharges, the sustained operating velocity will fall back to where prime mover power is balanced against drag and grade. The drive train will be the limiting factor in accelerative performance but the accelerative performance of yesterdays "muscle cars" may pale in comparison to the accelerative performance of a hybrid with a "muscled" drive train.

I am sure there will be more variations in storage and conversion methods but "Prime Mover Power Averaging", "Regenerative Braking," and "Peaking Power" will remain fundamental efficiencies in hybrid technologies whether it be wheeled vehicles, small unit electrical power production, or the myriad of other applications.

In closing I want to say the potential for significant enhancement of transportation efficiency still exists in both automotive and rail applications. Energy saving returns can come a lot quicker and cheaper than reinventing the technology. We have begun by sequencing traffic lights to traffic patterns and may soon expand that concept out to a 12,000-ton train that may never have to stop for a meet.

Gavilan

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#2

Re: Bright Idea: The 100-MPG Delivery Van

05/05/2009 7:16 PM

I would build a 101mpg delivery van for $449,999,999. This would save money and increase efficiency over the proposed 100mpg and $450,000,000 van. Just send the money.

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