We can buy a hybrid or electric vehicles and cover the roof of our homes in solar panels, but when it comes to other aspects of our daily lives a fossil-fuel reducing lifestyle is often a the whim of local governments or private businesses.
One we often forget about, at least until they wake you one morning with the clanking of trash cans, is garbage collection. Those big diesel trucks, typically rolling along at slow, uneconomical pace, probably aren't that green.
Now there's another option, for those businesses that choose to use it--a hybrid garbage truck.
Parker Hannifin's Runwise is a series hybrid drive system that uses not batteries but hydraulic pressure to drive an otherwise standard garbage truck.
It operates similarly to the Hybrid Air concept developed by French automakers Citroen and Peugeot, but rather than air it uses hydraulic fluid--more suitable for large applications like the truck.
Runwise replaces the truck's conventional transmission, but does still retain a regular engine with its own three-speed gearbox.
On start-up, the engine charges a high-pressure accumulator in the hydraulic system. When the driver presses the gas pedal, this high pressure is used to drive the truck hydraulically.
When the driver brakes, energy is pumped back from a reservoir into the accumulator, ready to drive the truck on the next press of the gas. Parker says Runwise can capture and reuse up to 71 percent of braking energy normally lost each time the driver brakes.
Eventually, as in the Hybrid Air system, the hydraulic energy can run out, at which point the engine can power the wheels through its gearbox.
Likewise, at speeds above 45 mph, the engine does the driving--though garbage trucks typically spend their time at low speeds, driving down the street making several stops.
There are several benefits to the system, the largest of which is fuel efficiency--Parker says the average garbage truck's fuel consumption reduces by 30-50 percent.
When a garbage truck uses 8,600 gallons of diesel every year, on average, the potential cost savings and pollution reduction are significant.
As regular hybrid drivers will know, vehicles with regenerative braking are easy on their friction brakes too, extending the life of pads and rotors.
Parker also extols the benefits of another hybrid familiarity--instant response. The hydraulic hybrid system gives drivers much better response than a conventional engine and transmission. Over repeated start and stop cycles, that means time savings too.
The company says the system can work with several different garbage truck chassis and bodystyles currently on the market and the firm already has several trucks in service--there are as many as 60 already in use in Florida.
It may not make your mornings much quieter, but after you've separated all your garbage for correct recycling, it'd be nice to know your local garbage truck is a bit greener too.