Have you ever thought about the carbon footprint of your money?

Everything we use has to be transported from place to place, including the cash in our wallets.

And the big, hulking diesel armored trucks that move money around are hardly the most fuel-efficient vehicles.

DON'T MISS: Armored Electric Chinese Police Patrol Car Is ... Words Fail Us (Dec 2014)

Hoping to temper the all-important emphasis on security with some green thinking, three companies have just unveiled a cleaner alternative to the traditional armored truck.

The 26,000-pound vehicle is a plug-in hybrid with a natural-gas internal-combustion engine, according to Autoblog.

Six trucks were converted by Efficient Drivetrains Inc. and North American Repower, and will begin hauling valuables around the Los Angeles area with Sectran Security next year.

Clean Energy Fuels natural gas refueling station Long Beach, California.

Clean Energy Fuels natural gas refueling station Long Beach, California.

Efficient Drivetrains has already tried to market a plug-in hybrid SUV in Asia, while North American Repower specializes in natural-gas conversions.

An armored truck seemed like a good platform for the joint project because these vehicles most of their time in urban traffic, making many stops for deliveries.

During stops, a standard truck's diesel engine is typically left idling for security purposes.

ALSO SEE: Why Aren't Natural Gas-Powered Long-Haul Semi Trucks Selling Better? (Aug 2014)

However, California regulations limit idling to 5 minutes, the partners say.

The powertrain's electric component offers a way around that issue, while the natural gas power helps to reduce emissions while running the engine.

The demonstration fleet of six trucks will conserve 31,000 gallons of diesel per year, and cut emissions by 99.9 percent, the companies claim.

2015 Chevrolet Impala Bi-Fuel Natural Gas

2015 Chevrolet Impala Bi-Fuel Natural Gas

Natural gas has proven to be more acceptable as a fuel for fleets than individual passenger cars.

The lack of public fueling stations makes owning a natural-gas car somewhat inconvenient, but fleet operators can secure supplies of the fuel to distribute to their vehicles.

After 15 years of selling a natural-gas powered Civic sedan, Honda has withdrawn that model for 2016 after concluding that prospects for natural gas-fueled passenger vehicles remained dim.

MORE: Prototype Natural-Gas Vehicles Use Gasoline As Range Extender (Jun 2013)

Since most fleet vehicles operate within confined service areas, operators count on them not straying too far from a centralized fueling source, often "back at base" every night.

The armored-truck project received a $3 million grant from the California Energy Commission, along with a matching amount of private funds.

While this project will only demonstrate these unusual vehicles, perhaps more will be built if security companies show interest.


Follow GreenCarReports on Facebook, Twitter, and Google+.