Oshkosh's Diesel Electric Hybrid Monster Truck

I’ve always wanted to get a big monster truck. Huge tires, sits really high off the road, good visibility, don’t have to worry about road obstructions like pot holes, goes in the snow, even take it off-road. The problem is that these big monster trucks don’t get very good gas mileage.

Well now Oshkosh Truck Corporation (OSK) has designed a truck using Diesel Electric Hybrid technology that increases fuel efficiency 20% over the truck it replaces. The HEMTT A3 truck is being built for the military, which is pretty demanding about reliability and performance.

Oshkosh says the truck is production ready. The truck has a 400 HP Cummins ISL Diesel Engine with a 305 KW electric generator. The generator charges a 1.5 MJ ultra-capacitor. The capacitor feeds power directly to electric motors mounted on the wheels. The vehicle can work off-road, climb a 60% grade, and achieve 65 mph on secondary roads. The truck weights 3000 pounds less than its conventional predecessor, but still can carry a 13 ton load.

The capacitor is the heart of the drive system. It stores the equivalent of 0.42 Kwh of electricity, equivalent to 0.035 gallons of gasoline (4.5 ounces). You can’t get very far on that amount of power so the vehicle does not work as a home plug-in. The capacitor does buffer the power from the engine allowing the engine to always run at an efficient speed. The capacitor provides for bursts of power when the vehicle accelerates and can capture the power from regenerative braking. That is what gives the vehicle its improved fuel economy.

The real point to discussing this vehicle is that this drive train technology could also be used on more conventional vehicles like cars or utility trucks. A capacitor in a car could allow for a smaller, lighter engine to be used. It would be optimized to run at peak efficiency. You can eliminate heavy parts like the transmission. More of the car becomes solid-state electronics which are very reliable. The capacitor also recovers the energy from braking. The number of cycles on the capacitor should be almost unlimited so it won't degrade over time like a battery.

Assuming a 20% increase in efficiency, a 30 mpg car becomes a 36 mpg car. If every car on the road today used this technology, we would save about 1.9 million barrels of oil each day, along with a reduction in greenhouse gas emissions. You also could add a battery to this design to create a plug-in vehicle. The battery would not need the capacity to power the entire car (making it cheaper). It would only re-charge the capacitor; sort of like how a battery on a camera charges a capacitor that powers the flash. You might never need to run the engine just traveling around town.

The vehicle design here is basically a solid-state version of a Toyota (TM) Prius. The Prius design uses a battery and electric motor to provide a mechanical assist to the power from the gasoline engine. The power assist is added to the mechanical drive train. The HEMTT A3 has a diesel engine that drives a generator that powers electric motors on the wheels. The capacitor provides an electrical assist to increase the power to the wheels for short periods of time. Both systems can recapture energy from braking. By allowing the engine to run at a more constant speed and recapturing energy both systems improve fuel economy. The Ford (F) Escape Hybrid uses this same type of system.

The Chevy (GM) Volt also is a similar system to the HEMTT, except that it uses a battery to provide power. The Chevy Volt has a gasoline engine that is only used to charge the battery in the car. The size of the battery in the Chevy Volt allows the car to be charged externally and operate for a considerable distance without any power from the engine. The size of the battery is sufficient to provide the current necessary for acceleration.

Diesel electric locomotive engines have been around for decades. The advantage here is the tremendous torque produced by the electric motors, which is very efficient in getting a very heavy train moving. It eliminates the need for shifting through numerous gears and a huge clutch.

Ultra capacitors have a lot of potential for creating hybrid cars. Capacitors are generally light in weight. They are solid state devices that can charge and discharge very fast, which can supply a lot of power when you need it. They are very efficient at storing electric energy. The constraints are that they can only store a fraction of the power stored in a battery and they can be expensive. I believe that high power capacitor technology will continue to improve and capacitors could be an important enabling technology to improve gas mileage and help solve our energy problems.

Disclosure: I have no stock position in any of the companies mentioned.

Comments

[Burty:]

John
Could you predict time range for "plug in" cars yo go commercial?
Who will be the big players?
The future is electric plug in cars where your plug in station is your home. Everything else is just buffers until the efficiency of nickel batteries are high enough.

2008 Jun 17 08:19 AM

[Global Warm...:]

I can't predict when electric cars will become viable options. Tesla is currently selling an all-electric car with a $109,000 price tag. It has very high end performance like 3.9 0 to 60 speed. 220 mile range. GM may be selling the Chevy Volt in 2010. That tells me that the battery technology is getting better. I look at this like many electronic devices where the first generation devices are bulky and expensive. Successive generations produce improved products at lower costs. Flat screen TVs, computers, cell phones, video games, etc are all examples. How fast electric cars happen, I don't know, but I do expect it will be worth watching.

2008 Jun 17 11:32 AM

[keithfeather:]

Who supplies the capacitor?

2008 Jun 17 05:51 PM

[lefty:]

If capacitors are expensive, someone is being ripped off. You can build a hundred of them with the foil and wax paper from your kitchen.

2008 Jun 18 07:07 AM

[Marcus Aure...:]

lefty,

We are not talking about kitchen table capacitators. The base unit to measure capacitance is the farad. A 1-farad capacitor can hold 1 amp-second of electrons at 1 volt (see electronics.howstuffwo...) and guess what? In terms of capacitors that is HUGE, typical capacitance is measured in terms of micro farads and it is not uncommon to see PICO farads.

Not only do the things have to hold a lot of charge they have to do so safely.

2008 Jun 20 12:56 PM

[Marcus Aure...:]

The ultra-capacitors are supplied by NASDAQ::MXWL

2008 Jun 30 03:08 PM

[Diegojames:]

It appears HONDA GX this December 2008 will be the first alternate fuel vehicle other than the VODKA powered e -85 Food INFLATING CONGRESSIONAL MISTAKE TO MAKE FARMERS RICHER THAN CEOs at FANNIE AND FREDDIE and win the incompetence award of the CENTURY.
THIS capacitor /diesel/electric motor combo is too smart for DETROTT/GM/FORD. Maybe after 2010 .
Will go long on OSK-Oshkosh Monday. Had a position in PCAR for the new propane/diesel long haul large trucks. Any thoughts out there???
Airlines are to costly,over staffed at the top and big money losers that the BANKS will not be able to afford soon????
Diego

2008 Sep 07 04:54 PM