By Allen Penticoff
A few weeks ago, I was doing a little business at the Chicago-Rockford International Airport when I saw a large earth excavator with the word “Hybrid” emblazoned on its flank. I took a couple of photos with my cell phone and went on home to do some research on this curious beast.
What I found was the new Komatsu HB215LC-1 (second-generation PC200-8) uses an electric drive system for the upper structure. I believe most excavators use hydraulics to turn the upper structure, and thus must be under power constantly. Komatsu’s electric drive system allows them to incorporate a giant electrical capacitor to absorb the energy dispersed as the upper structure slows down — then the power stored in the capacitor is released as the upper structure accelerates in the next turn.
This technology is quite ingenious. Imagine — an excavator (large back-hoe) that spends all day swiveling back and forth. Dig up dirt or whatever, swivel over, dump into truck. Repeat, repeat, repeat. Each time it swivels either to scoop up or dump, there is acceleration and deceleration, as it must move from each stopping point. Komatsu found a way to capture the wasted energy, then get it back. The result, they claim, is a 25 percent reduction in fuel consumption — up to 41 percent if the job site requires the upper structure to turn more frequently, compared to their own non-hybrid version of the excavator.
Capacitors are like batteries, but are able to absorb and disburse electricity very rapidly. The flash in your camera has a capacitor — that is what is charging while you wait to take the next snapshot. But when you press the button, the electrons flow out in one great rush, creating a voltage far greater than the little battery that fed it can create. Ignition systems in cars have capacitors for this same reason. Komatsu figured out that getting a big jolt to the drive motor for acceleration was more important than trying to drive the whole system with batteries and keeping them charged.
This sort of hybrid technology could be used in other start-stop applications. Waste hauling trucks move a little, stop, move again, stop again a great deal. This sort of acceleration, deceleration would be similar to what the HB215LC experiences. Mail delivery vehicles come to mind as another application that would benefit from this sort of drive system (although I wouldn’t know my mail had arrived if it were not for the bad muffler on our mail person’s Jeep).
Being a guy, I’d long wanted to try my hand at running an excavator — and a bulldozer. Not too many opportunities for that — but recently I got a chance when visiting the John Deere Pavilion in Moline, Ill. The pavilion is a vast display of John Deere products old and new. You are free to climb onto most of them. One of the several interactive displays was the excavator simulator. It is a chair with two excavator control sticks — one for both hands — and a display screen. The view is as though you are in the cab of the excavator, and you are challenged to see how much (in dollars worth) dirt you can dig up, swivel 90 degrees and drop into a waiting dump truck. The faster you go, the more money you earn — but there are penalties for damage to the truck. I never damaged the truck, but it took two turns at the simulator to begin to really get the hang of it — then my friend wanted to leave. Darn, I’d have stayed at it all day. I found the John Deere Pavilion to be a very informative free exhibit.
I would like to close out this week’s column by responding to a letter to the editor sent in by Tom Harris of the International Climate Science Coalition who pooh-poohed my statement (“Mr. Green Car: Why you should care about Keystone XL,” Oct. 5-11 issue) that most climate scientists believe we will experience more extreme weather events as a result of climate change. While having an organizational name that sounds like a lot of people — only 2 percent of the thousands of climate scientists are doubters of human-induced climate change. Harris is apparently among those few. His organization is tasked with monitoring the Internet for the keywords “Keystone XL” and to challenge those of us who are concerned with the building of that pipeline. Harris said his organization is funded by “individuals” — it takes little to figure out that some of those individuals are the executives of the Canadian tar sands oil industry. I stand by my statement as having plenty of scientific support.
Green Car Technology event Nov. 18
Allen Penticoff, Mr. Green Car, will be conducting a two-hour program about the state of Green Car Technology at the Center for Learning in Retirement (CLR) from 10 a.m. to noon, Nov. 18. To join CLR or register for the program, contact CLR at (815) 921-3931 or visit www.rockvalleycollege.edu/clr.
From the Nov. 16-22, 2011, issue