If we really want to worry about such stuff, we better stop producing just about everything.
And about mining vehicles, here is
the largest EV in the world and it never needs to be charged.
-Don- Reno
It's been a long time since I got the degrees in Mechanical Engineering and Electronics, but after reading the article that the link above about the worlds Largest EV that
never needs charging, my old brain and ancient math skill say "Something ain't right here, there ain't no free lunch or perpetual motion"....
Here's part of the article:
"The dump truck, at 45 tons,
ascends the 13-percent grade and takes on 65 tons of ore. With more than double the weight going back down the hill, t
he beast's regenerative braking system recaptures more than enough energy to refill the charge the eDumper used going up.
Ok, that would mean that it produces a surplus of energy, and would never need recharging from an outside source, HOWEVER, read on...
The Elektro Dumper—eDumper for short—made by Kuhn Schweitz, is based on a Komatsu HB 605-7: 30 feet long, 14 feet wide, and 14 feet tall. The tires are six feet high, and the dump bed reaches to more than 28 feet, fully raised.
Kuhn Schweitz adds a 600 kilowatt-hour battery pack—big enough for six, long-range Tesla Model Ses—from Lithium Storage that weighs 9,000 pounds.
CNN
recently brought Formula E driver Lucas DiGrassi along to test drive the machine, owned by Swiss cement company Ciments Vigier SA.
He reported reaching the top of the grade with 80 percent, then recovering battery charge to 88 percent on the way down (not unlike our writer's
experience with a Chevrolet Bolt EV in the Rockies.)
Huh? It took 20% going up but only gained 8% coming back down?
Marking that trip around 20 times a day,
Kuhn Schweitz says the eDumper produces 200 kwh of surplus energy every day, or 77 megawatt-hours a year. A typical dump truck uses between 11,000 and 22,000 gallons of diesel fuel a year. That saves up to 196 metric tons of global-warming carbon-dioxide gas a year."
End of my quoting the article.
Ok, if it starts up that 13% grade with a 100% charge in the battery, and it gets to the top with a 80% charge remaining, then it obviously used 20% of the charge to climb that 13% grade while empty.
Then it says the down hill trip once loaded the battery recovered
TO 88% of full charge thanks to the regenerative braking.
OK, so a trip up takes 20% of the charge, and you regain 8% of it on the way down.........my math says that with a net loss of 12% per round trip, you are gonna get 7 round trips, starting with a 100% battery charge, before that battery is flat dead and will need recharging from an outside source.
So I definitely can't see it producing an surplus of 200 kwh of energy per day, to my way of thinking it is losing energy with each trip, or did I miss something due to my great age and advancing senility?
Thinks like friction loss get in the way, and also, as the temperature rises, the efficiency of those regenerative brakes, which are nothing more than alternators or DC generators, one or the other, will decline as well for as the copper windings in them heat up, the resistance goes up and so current flow will decline.
That's because in metals, the thermal conductivity is mostly a function of the motion of free electrons. As the temperature rises in a metal, the molecular vibrations increase which results in turn in a decreasing of the mean free path of molecules, and that means they will then obstruct the flow of free electrons, and that reduces the electrical conductivity.
Unless of course they are made of some room temperature super conductor that we haven't heard of yet.
