Clever. It can do this because it travels uphill empty and comes downhill full.
Clever. It can do this because it travels uphill empty and comes downhill full.
I'm not expecting them to meet their goal of producing excess energy.
[1] weighing in at 45 tons when empty plus 65 tons of loading capacity -- https://phys.org/news/2017-09-e-dumper-world-largest-electri...
The weight is 45 tons going up, and 45 + 65 = 110 going down, right?
In a 100% efficient no friction wonder world, the load needed would be 45 tons going up, and 45 + 45 = 90 tons going down. This would balance out to 0 battery usage.
Since our going down weight is 110 tons and not 90 tons, we have 110 - 90 = 20 "extra tons" that can go to things like friction and imperfect conversion of energy forms.
efficiency * 110 tons * gh = 45 tons * gh
efficiency = 45 tons / 100 tons = 40.9%
The ratio will tell you how much "excess" energy you get, the efficiency of converting that from mechanical energy to stored charge and back to mechanical energy will tell you how much energy you will have 'left'.
And as long as you don't run out of battery capacity to hold energy you're capturing on the way down, the math just works.
Based on the mass ratio the magic number is 69.2% to hit break even assuming you always load to 65 tons. If you load to 55 tons (15% margin of error) the magic number would be 82% efficiency.
EDIT: See another comment that the ratio is 110 tons to 65 tons, not 65 tons to 45 tons. That improves things. Total system regen efficiency has to be above 41%. That number crosses 60% when the load is down to 30 tons.
http://www.komatsuamerica.com/equipment/trucks/electric
http://www.cat.com/en_ID/products/new/equipment/off-highway-...
Basically this kind of trucks have a huge diesel engine and electric generator and four electric motors, one for each wheel.
Power is lost in the generation and powering of the electric motors of course, but there is no transmission overhead (though there is a reduction gearbox on each motor anyway).
Although as mentioned previously it needs 69.2% and 100% loading to break even. Could be a challenge.
[1]: http://gizmodo.com/these-little-electric-wheels-will-save-ai...
Note that Tesla is switching to a permanent magnet motor for the Model 3, which is an interesting development. I'm not sure why, but I hear the magnets have become a lot cheaper than they once were.
Large electric motors, 90-95% efficient.
Battery round trip efficiency, 80-85%.
High voltage inverters, likely above 98%.
Roughly seems like regen round trip efficiency would be at least 63.5%.
The weight ratio is (45 tons)/(65tons + 45 tons) = .409
Unfactored are rolling friction loses.
> The weight ratio is (45 tons)/(65tons + 45 tons) = .409
Sproing! Discussing it here I realize that I kept thinking about it as 'can the energy of bringing 65 tons down equal the energy of 45 tons up' but you are absolutely right that really its 110 tons down, and 45 tons up. That certainly helps. E(loaded) -> %eff capture -> E(bottom) -> %eff drive -> E(unloaded)
And as long as you can multiply the two efficiency fractions and stay above 41% you win.So the energy that the truck is gaining is really the stored potential energy you got from the kinetic energy of bringing your food home from the store (or other similar things).
I think the idea is really clever, to utilize that kind of latent stored energy to make your trip more efficient.
Again, trash is not involved.
Same reasoning applies though, albeit other processes doing the lifting.
I don't know enough about mines, and googling "most common mine design" isn't cutting it. Could anyone weigh in with more insight? The only big mines I've seen look to be pits, like the Bingham Copper Mine near SLC.
I do remember reading something about ore trains in some Scandinavian country using regenerative braking to power nearby towns and its own trip back up.
The logistics of feeding the power back to the grid are also a bit wonky. Is it going to be dragging a cable behind it? Is there an inductive charge/discharge pad that it drives over? The article has no useful details on this, and the whole idea seems rather half baked.
> An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a battery or fuel cell.
0- https://www.google.ca/maps/@49.6515022,-114.8604751,14053a,3...
Edit: autocorrect
The example in the article was a cement factory - cement is basically made from limestone, and you can find mountains of the stuff. In general, you're probably looking at sedimentary deposits that have been uplifted - coal was another example someone else gave, you can probably also find mountaintop salt mines.
At least it did when I was there, this was before the big collapse there a few years ago...
Moving away from coal would have a much greater positive environmental impact than engineering the hell out of the hauling efficiency. Like wind power, solar power, hydro power, for instance, all of which don't need any hauling once built.
They use electric locomotives and traincars full of rock, along with a big hill, as energy storage. Drive it up during cheap energy times, and back down when you need to produce electricity.
The train left the station in the valley empty and returned fully loaded with logs from the mountain. At first they didn't believe their own measurements, but it was effectively generating electricity.
Admitting up front I know very little about mining: Aren't most mines operating today of the strip variety? I.e. a big damn hole? My mental picture of the places most of these trucks operate is where they drive into the hole empty and come back out full, uphill. Am I wrong?
Even so this type of mining tends to happen in mountainous areas. Mountains are places where minerals are pushing up from deeper areas, and they're subject to more erosion, so you find a lot of valuable minerals. They are also colocated with seams, which are chock-full of minerals. Valleys and low spots are places where sediment accumulates and covers minerals, and are rarely worth mining. The altitude of a mine is usually much, much greater than the relatively negligible depth of the mine itself.
Again, trash is not involved.
An escalator that moves people down could conceivably work without any external power source other than the people.
I wonder why the journalist chose to use the scare quotes, as if the heating up was metaphorical.
What is the uphill/downhill ratio of dirt moved in the world?