Thread by @NeilRingdahl

#Mining with Electric machines: A modern miracle to save the environment or a pipe dream? 🧵
I'll discuss both open pit & underground apps.
For 60yrs, engineers have been innovating electric mining machines b/c they're cheaper. An electric dragline moves 60t each swing.😳1/

These monsters are so huge, a ship's diesel engines don't cut it. Way before I was even born, the clever guys worked out its cheaper -on a per-tonne basis- to use electric motors connected to the grid. They work well and are excellent in soft-rock stripping operations. 2/

Mining is about LOGISTICS of moving large masses of material to expose what is valuable & then move the valuable material to extract the metal. All this movement requires a LOT of energy.👇If you have ever dug your own swimming pool, you understand.😏 3/

It may come as a surprise to you, but most of these huge off-highway trucks have been running ELECTRIC DRIVES for at least 50 yrs now. Its because a mechanical drive is more energy INEFFICIENT than electrical drive system. Its about the number of moving parts (detail👇). /4

Sadly, engineers have for YEARS not been able to get away from diesel drives operating these electrical systems b/c its simply the most reliable way to generate power on a mobile machine like a truck. I'll get to H2 & batteries later. /5

Why are off-highway trucks with only mechanical drives (like the Cat 789) sometimes still used? It can be argued they r more robust & reliable over the operating life which is about 18-25,000 hrs. Higher fuel cost, w/ lower parts consumption sometimes still makes them cheaper. /6

Now the whole greening movement has got people considering battery or hydrogen operated trucks using new technologies. Great stuff & there are many examples, incl. this one below. Unfortunately, it still has an Archilles heel. bit.ly/3F4Oxdv /7

The challenge is in the scale RQD: You can't get batteries big enough to deliver the power required to move huge payloads for 19 HOURS PER DAY, EVERYDAY. Even @elonmusk 's teams have battled to go bigger to 18 wheelers👉 bit.ly/3gyfNHx /8

So we find ourselves lacking the technology to go bigger on batteries; perhaps there is more promise in using hydrogen instead of diesel? Anglo are running an interesting prototype👇👉bit.ly/3ABaxKkbut it has yet to demonstrate tangible results. /9

Colour me a cynic if you like, but I have always had a keen interest in testing new mining tech & we burnt our fingers doing so too, on this very mine about 22yrs ago (recall my Friday mayhem post from a couple of weeks back)! This is not to say we shouldn't keep trying!; /10

Just the % of success of new ideas is very, very low and we should be careful not to fall into the trap over committing to something that is still impossible.
So what does work? Well I can tell you that trolley-assist 👇has been used with some success for well over 40yrs /11

Trolley assist is a pain to install & operate in an open pit but it might make one of these new power systems more viable. Yet it's still doubtful to me whether any combination of these would be more cost effective for many years to come or at all viable over a life of mine. /12

My personal thought on the battery or hydrogen solutions is that they HAVE to be able work on their OWN, without being connected to a hybrid (which might then make them more economic), but until the tech is tested and stands proven its own, it'll never take off. /13

What about shovels, excavators & loaders? The good news is most shovels already are widely operated using pure grid power& r cheaper than their diesel alternatives, provided grid power is still reasonable!😄 Excavators are mostly diesel b/c they're standing on broken material,/14

On the left we have a large diesel driven excavator (reverse bucket) on the right a diesel wheel loader working with a diesel truck with mechanical drive. This type of equipment is typical for remote sites with no grid power, but also for practical reasons./15

Underground trucks have exactly the same challenges as open pit trucks and operate in harsher conditions, but b/c they are smaller will more likely benefit from better battery technology first. This is offset by the smaller scale making the cost differential way less impactful/16

Scoops or LHD's are generally diesel operated but some mines with fixed LHD routes (like a block cave) are able to use a electric LHD with a trailing cable connected to the grid. These cables can be a real pain, often get damaged etc, but they do work okay. /17

Battery operated scoops are also available and used especially when the scale is smaller, (where batteries can last a bit longer). Where batteries really work well is on small electric locomotives under ground where they have been used for years and years. /18

So, until batteries are able to produce >1MW for >19/day and weigh less than 20tonnes, I'm afraid your dreams of saving the planet by mining green are just that pipe dreams. Sorry.😄
But, what about the smaller UG stuff? /19

Its a case of economics: The smaller equipment can work with batteries but you'll need double the No. of machines with all the congestion issues that come with it.

But in time - who knows- perhaps we will innovate a new nuclear power drive train & all our issues b solved./end