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.
 weighing in at 45 tons when empty plus 65 tons of loading capacity -- https://phys.org/news/2017-09-e-dumper-world-largest-electri...
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
Although as mentioned previously it needs 69.2% and 100% loading to break even. Could be a challenge.
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.
E(loaded) -> %eff capture -> E(bottom) -> %eff drive -> E(unloaded)
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.
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%
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.
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).
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.
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 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.
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.
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.
At least it did when I was there, this was before the big collapse there a few years ago...
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.
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?
But things like this demonstrate why that is the wrong way to look at it. We can, and absolutely should, electrify everything. The whole supply chain.
The truck in the mine, the smelting factory, the assembly line, the warehouse, and the big rig that delivers it to you. There's no reason why every one of these couldn't run on renewable electricity. The only reason they don't is because until recently it was more expensive, but that is no longer true. The total lifecycle carbon impact of everything we make can go to nearly zero as all these points electrify and as our grid migrates over to renewables.
That it can't happen all at once is no reason not to start.
"A lot" = 15% more. Approximately 1 ton of extra emissions, which it takes a daunting 4,900 miles to pay back- less than 5 months of the average American's driving. A great deal of this pollution comes from energy use- that report says that if the grid was powered by 80% green energy then manufacturing a BEV would produce 25% less pollution than a normal car.
Once you get the consumers all using one fuel it's an order of multiple magnitudes easier to then switch out the energy supply with something cleaner.
Until the majority of the world's energy usage is electrified, it's a completely pointless thing to bring up how that electricity is actually generated.
Interesting claim. I'm not familiar with NMC batteries.
Here's what wikipedia says:
> Handheld electronics mostly use LIBs based on lithium cobalt oxide (LiCoO2), which offers high energy density, but presents safety risks, especially when damaged. Lithium iron phosphate (LiFePO4), lithium ion manganese oxide battery (LiMn2O4, Li2MnO3, or LMO) and lithium nickel manganese cobalt oxide (LiNiMnCoO2 or NMC) offer lower energy density, but longer lives and less likelihood of unfortunate events in real world use, (eg, fire, explosion, ...). Such batteries are widely used for electric tools, medical equipment, and other roles. NMC in particular is a leading contender for automotive applications. Lithium nickel cobalt aluminum oxide (LiNiCoAlO2 or NCA) and lithium titanate (Li4Ti
5O12 or LTO) are specialty designs aimed at particular niche roles. The newer lithium–sulfur batteries promise the highest performance-to-weight ratio.
So, it's another kind of lithium-ion battery.
They're both significantly cheaper than LCO (the most common) and because of that NMC has become a lot more common than it was. They're also much better behaved (ie happy to put out high-power bursts, temperature-stable, and less likely to ignite), but last longer than other chemistries like FePO4 (which not well behaved but quite hard to ignite).
Here's an example diesel-electric hybrid dump truck: https://en.wikipedia.org/wiki/Liebherr_T_282B
Are there existing hybrid trucks of a similar size to the one in the article?
Well, some are. I presume some run on other power but I've not seen one.
50-odd tonnes and I've witnessed zero to 80km/h in about 6 to 10 seconds or so.
But, yes a nice big yellow machine running on batteries is an impressive milestone.
For those in Birmingham UK: St Paul's to Jewellery Quarter is a longish bit of track just outside the city centre.
Like Terex_33-19_"Titan" https://en.wikipedia.org/wiki/Terex_33-19_%22Titan%22
That sounds very doable in the battery charge that allows a Tesla Model S to travel from LA to NY.
An addition or alternative to a powerwall or whatever the tesla home battery's called?
Be interested to know what range they anticipate from the 4.5 tons of batteries
The old UK milk floats had a range of 60-80 miles http://www.milkfloats.org.uk/faq.html
And by the way all Diesel Submarines and Ships are also electric drive trains.
Terex_33-19_"Titan" for instance was released in 1973.
https://en.wikipedia.org/wiki/Terex_33-19_%22Titan%22 had 2,461 kW gross power.
Or this one released in 2004
When it was released it had 2,000 kW of electric drive haul.
So your comment is a classic example of lame talk without reference, talking out of a hat isnt worth anything.
But this truck would need to be able to back up, make u-turns, etc, while fully loaded.
So the motors must be strong enough to drive it uphill even when fully loaded, if only simply for the sake of positioning and maneuvers.
Also trains have been doing it for decades.
> Modern generators with field coils are self-excited, where some of the power output from the rotor is used to power the field coils.
In the grand scheme of things it's not that big a deal since the primary energy used to extract materials is an order of magnitude or two less than the energy used to process them. But still, the less oil we burn the better!