**Engineering Innovation: The Gravity-Powered Mining Train**
In the ever-evolving landscape of renewable energy technologies, one concept that consistently sparks fascination is the idea of perpetual motion machines—devices that supposedly operate indefinitely without an external energy source. While such concepts remain firmly rooted in science fiction, recent advancements in engineering have brought us closer to harnessing natural forces like gravity to achieve sustainable and efficient transportation solutions. One such innovation is the Infinity Train, a groundbreaking project by Fortescue Metals Group (FMG) in partnership with Williams Advanced Engineering, designed to revolutionize mining transport.
### Introducing the Infinity Train
The Infinity Train, as its name suggests, operates on a principle reminiscent of perpetual motion but within the confines of thermodynamic laws. This innovative train transports iron ore from FMG's mine in Pilbara, Western Australia, to Port Hedland over 280 kilometers away, using only gravitational potential energy and regenerative braking technology.
The concept is deceptively simple: as the fully loaded train descends from the mine to the port, it generates kinetic energy which is converted into electrical energy stored in onboard batteries. Upon reaching the port, the empty train, now lighter, uses this stored energy to power its return journey to the mine. This system eliminates the need for external energy sources like diesel or electricity, marking a significant leap towards sustainable mining operations.
### The Physics Behind the Innovation
At the core of the Infinity Train's operation lies the conversion of gravitational potential energy into kinetic and then electrical energy. When the loaded train descends, its mass at height (450 meters above sea level) translates to gravitational potential energy, calculated as 326 GJ or approximately 91 MWh. Upon reaching the port, this energy is stored in batteries, which then power the return trip.
The regenerative braking system plays a crucial role here. During braking, the electric motors on the train act as generators, converting kinetic energy back into electrical energy and storing it in the batteries. This technology, while not new in itself (it's commonly used in electric vehicles), is applied here to achieve 100% energy savings for the return trip.
### Technical Challenges and Efficiency
Despite its promise, the Infinity Train faces practical challenges. The regenerative braking system must operate at high efficiency to ensure that enough energy is stored and converted back into gravitational potential energy during the ascent. While Rosie Barnes estimates that at least 54% of the kinetic energy needs to be converted, real-world factors like rail friction, aerodynamic drag, and mechanical inefficiencies can increase this requirement.
Barnes also raises an important point regarding energy storage. Each trip requires a battery system capable of storing up to 90 MWh of energy. Using Tesla Megapacks as an example, each pack weighs about 23 tonnes and provides 3 MWh of storage. For the Infinity Train, this would mean carrying approximately 30 such packs, adding 690 tonnes to the train's weight—a manageable 2% increase in empty weight but still a significant consideration.
### Broader Implications and Comparisons
The Infinity Train is part of a broader shift towards sustainable mining and transport. Fortescue's commitment to reducing Scope 1 emissions by 11%, which includes diesel consumption, aligns with global decarbonization efforts. Similar projects like the e-Dumper, an electric mining truck developed in Switzerland, demonstrate the potential for such technologies across different applications.
While the Infinity Train is a highly specific solution tailored to its route and cargo, it highlights the feasibility of gravity-powered transportation on a large scale. Its success could pave the way for similar projects, particularly in regions where topography allows for downhill transport routes.
### Conclusion
The Infinity Train challenges our perception of traditional energy systems by demonstrating how natural forces like gravity can be harnessed to create efficient and sustainable transport solutions. While it doesn't break the laws of thermodynamics, it redefines efficiency by maximizing the use of potential energy and minimizing reliance on non-renewable resources.
As Rosie Barnes notes, the project is not just an engineering marvel but a testament to the importance of innovative thinking in addressing global challenges like climate change. By pushing the boundaries of what's possible with regenerative braking and gravitational energy, the Infinity Train sets a new standard for sustainable mining operations, offering a glimpse into a future where technology and nature work hand in hand.
"WEBVTTKind: captionsLanguage: enOne of the perks about having amediumly-popular YouTube channelon renewable energy technologiesis that I get contacted by a lotof inventors who tell me thatthey have come up with a way toget free energy via some sort ofcomplicated mechanism. In fact,I get so many of these that Imade a whole video on the lawsof thermodynamics and whyperpetual motion or free energyisn't a thing. And that just ledto a flood of people contactingme to tell me that they hadfound a way to beat the laws ofthermodynamics, and do I want toinvest in it or maybe promote iton my channel. So yeah, thoseare annoying, but maybe inresponse to them. I kind of loveengineering projects that looklike perpetual motion machines,but actually aren't. One exampleis a video I made explainingVeritasium's video on RickCavallaro's downwindfaster-than-wind device. Ittakes most people, including me,quite a while to get their headaround the idea that it workswithin the rules of physics, notby creating free energy and notby some kind of scam. Andtoday's video is another in thatvein, it's a mining train that'spurely gravity powered. Itdoesn't use diesel, it's notsolar or wind powered or anyother kind of renewable energy.It simply charges its batterieswhen it's traveling downhill andthen uses that charge to getitself back uphill to where itstarted. How is that not aperpetual motion machine? Inthis video, I'll be answeringthat question talking about howit uses gravitational potentialenergy and regenerative brakingto make this roundtrip withoutviolating the laws ofthermodynamics. And I'll alsotalk about other similarprojects and how much thistechnology can scale to helpdecarbonize transport and miningglobally.I'm Rosie Barnes. Welcome toEngineering with Rosie. Let's goback to this gravity-poweredtrain, what's going on there.It's a project that wasannounced by Fortescue MetalsGroup earlier this year inpartnership with WilliamsAdvanced Engineering, and that'sWilliams of F1 fame who FMGacquired and they've given thisproject a very catchy but prettymuch ungoogleable name, InfinityTrain. It's a train that willtake iron ore from their mine inPilbara in Western Australia tothe port. According to theirpress release, theirregenerating battery electriciron ore train project will usegravitational energy to fullyrecharge its battery electricsystems without any additionalcharging requirements for thereturn trip to reload. The ideais that the a train will traveldownhill from the mine to theport carrying the payload andgenerate and store energy inonboard batteries on its waydownhill. And then because thecars are lighter on the way backup to the mine after they dropoff all that iron ore at theport, they'll need less energyfor the return trip than if theywere full so they can power thewhole return journey with theenergy they stored on the waydown. This is really similar toa simple system that's been usedin mining sites since the 1600s.Ropeways like this one that TomScott visited for a video lastyear can be used to transferproducts from a minor to anearby and lower locationwithout any additional energyinput. Loaded cars glide down azip line which pulls acorresponding empty car goingback up. The Infinity is asimilar idea. But since theFortescue mine is a littlebigger and a lot further fromthe port, the required ziplinewould have to be hundreds ofkilometers long and thick enoughto pull tens of thousands oftonnes. So obviously, they'renot doing that instead of usinga ropeway, the Infinity Trainstores energy onboard instead,like the old timey ropeways theInfinity Train convertsgravitational potential energythat's stored in the mass of theiron ore sitting at some heightabove sea level into kineticenergy of the moving train. Butthen the difference to theropeway is that in the Infinitytrain, regenerative brakingconverts that kinetic energyinto chemical energy that'sstored in batteries on thetrain, you may have firsthandexperience of regenerativebraking if you drive an electricvehicle, or in fact, if youtravel a lot on electric ordiesel-electric trains, whichcommonly use the technologythese days, the way it works isthat during braking, theelectric motor actually runs inreverse. So instead of usingelectricity to turn the motorand drive the wheels, the wheelsturn the motor and the motor nowacts as a generator. Theresistance from this slows thecar or train and the electricitycan be used to charge a battery.To power the train back up tothe mine, the electric motorruns in its normal directionpowered by the battery. And asit regains elevation, some ofthe battery stored energy isconverted to gravitationalpotential energy. Theinteresting thing about thisproject is not really theregenerative braking. That'spretty much old news. It's beenvery common in passenger trains,especially for at least adecade, but those trains allneed to be charged from anexternal energy source, whereasthe Infinity Train does not.Regenerative braking on normaltrends can yield energy savingsof about 8-17%. And even higherin very dense suburban networksthat do a lot of full stops andstarts but for the InfinityTrain, it's a 100% Saving whichis only possible because of thespecific nature of the train andits route. The train itselfmakes a round trip from the mineto the port and back again butits load only makes a one waytrip, strictly downhill only andthat's the reason why it's not aperpetual motion device. Thegravitational potential energythe load held when I was at themine doesn't need to berecovered as the train returnsfrom the port, that energy canbe converted to power the trainback up the hill. Energy isconserved, there's no freeenergy needed. The big advantageof this is that there won't needto buy any diesel, andconsidering that Fortescue'srail operations used 82 millionlitres of diesel in 2021. Evenif that was only $1/liter thatmeans they're currently spending$82 million per year in diesel.And because they won't ever haveto charge the batteriesexternally, they don't need tobuy electricity and they don'tneed to install any charginginfrastructure. Now I couldn'tfind out how much of that 82million litres will beeliminated by specifically bythe Infinity Train project andFortescue have only mentionedproject development costs of 50million. They haven't said whatthe capital cost to actuallymodify the trains is, so it'snot really possible to get anidea of the financial paybackthey can expect from theInfinity Train project, though,I mean, I expect that will turnout to save the money, at leastin the long run. And in themedium term, it will be part oftheir announced commitment to benet zero in Scope 1 and 2emissions by 2030. Part of thatis a commitment to get offdiesel entirely within the nexteight years. If you're alongtime viewer of Engineeringwith Rosie, you might have seena few of my other videos onenergy technologies that involveconversions of gravitationalpotential energy. It's kind of atheme for me these days. Thisincludes pumped hydro and otherkinds of gravity energy storage.And I've mentioned before thatone of the reasons that I lovemaking videos about this kind ofthing is that the basic physicsbehind it is so simple, and thatmeans that it's easy to checkthe claims of new technologies.So let's do that now. TheInfinity Train weighs 40,000tonnes empty and can carry34,400 tonnes of iron ore. Ittakes that 34,400 tonnes of ironore from Cloudbreak mine at 450metres above sea level to PortHedland 280 kilometers away, andit completes the trip in aboutfive hours. The equation tocalculate gravitationalpotential energy is simply masstimes gravity times height, sowhen it starts its trip downfully loaded, it has 326 GJ ofgravitational potential energy,which is about 91 MWh. And ofcourse, when it's at the port,it has no gravitationalpotential energy as it's at sealevel. To get the empty trainback up to the mine, it willneed to regain 176 GJ or 49 MWhof gravitational potentialenergy which needs to come fromthe batteries. 176 divided by326 equals 54%. So theregenerative braking systemneeds to be able to convert atleast 54% of the kinetic energygained going down into usableenergy. And this definitelyseems plausible to me because Iknow that regenerative brakingsystems on cars can achieve muchmore than that. However, this isnot taking into account lossesfrom things like rail friction,aerodynamic drag, mechanicalefficiencies, etc, which wouldresult in a higher energyrequirement for the train toclimb back up and lower energyrecovery going down. So let'sjust add in very rough estimatesfor those losses, we will assumethat running resistance accountsfor 37% of energy consumption, Igot that figure from the low endof a published study onpassenger trains in Japan, I usethe low end because I assume amining train moves prettyslowly, and it doesn't stop andstart much compared to apassenger train. And in fact,37% may well be too high, thetrain needs 49 MWh to climbwithout losses. So with lossesincluded, it will need 78 MWh intotal, which is still less thanthe 91 MWh we have to work withfrom the gravitational potentialenergy at the mine. But we'regoing to need to convert it with85% efficiency, which is prettyhigh. Remember, though, thatI've used a lot of estimates andalso some basically wild guessesat some of the numbers here. Soit could be 10 or 20%. Less thanthat it wouldn't surprise me.Fortescue's CEO Elizabeth Gainesdoes mention that the InfinityTrain has the capacity to be theworld's most efficient batteryelectric locomotive. And perhapsit will have to be but certainlythe numbers don't suggest thatthe project is physicallyimpossible. So the physics makessense, at least at theback-of-an-envelope level ofaccuracy, it doesn't appear torely on any kind of free energyor perpetual motion. But theredoes remain one big practicalissue, energy storage. Each tripwould require an energy storagesystem capable of storingsomewhat less than 90 MWh ofenergy per train. A 3 MWh TeslaMegapack weighs about 23 tonnes.And it's the size of a shippingcontainer.So if we have 30 of those, it'san extra 690 tonnes that needsto be added to the trainsweight, and that needs to becarried uphill as well asdownhill, which means we'llactually need more energystorage and therefore morebattery mass. So you know, wereally ought to go back anditerate our calculations toaccount for this. But 690tonnes, it's only about 2% ofthe trains empty weight. So Ithink it's okay to leave itthere. To me, it clearly makessense for for you to do itprobably purely for financialreasons. And plus, you know,it's part of the target todecarbonize mining operations by2030. Fortescue's dieselconsumption represents 11% oftheir Scope 1 emissions, soprojects like this will helpthem to reduce that. But can weroll this out on a large scale?Is this going to help us reduceemissions from mining in ameaningful way? Probably not.This is a super specific projectthat only just works out atleast according to my roughcalculations. This projectwouldn't work if the load had totravel uphill, or even if it wasjust level from the mine to itsdestination, and it wouldn'twork if they're runningresistance was any higherbecause, say, it wasn't a lowfriction train, but instead atruck and in fact, there isactually a mining truck that ispretty similar in concept to theInfinity Train. It's called thee-Dumper. It was developed by aSwiss company KUHN Schweiz AG,they converted a diesel miningdumptruck to what they'recalling the world's largestelectric vehicle, though I'm notsure what they count as anelectric vehicle. I mean, I knowthat there are plenty ofelectric trains and electricferries in the world that Iwould call electric vehicles andI would expect that they arebigger than this mining truck.So I'd rather call the e-Dumperthe world's largest electrictruck rather than the world'slargest electric vehicle. Butthat's just being pedantic. Itweighs 100 tonnes when fullyloaded, and has a 600 kWhbattery with regenerativebraking that recovers energy asit drives downhill carrying aload of rocks. It then travelsback uphill using that energy.But in most cases, it's not 100%self sufficient. So for somereason, Formula E driver LucasDi Grassi had a go in it and hesaid \"we went out of here with90%, we went all the way to thetop, we arrived with 80% batteryloaded up and on our way back,we recovered 8%. So we came backwith 88%. That's actually prettycool.\" And I agree, Lucas,that's pretty cool. And itapparently saves 50,000 tonnesof fuel per vehicle per year,which is definitely cool. But ifyou're losing 2% charge eachround trip it's not 100%gravity-powered like theInfinity Train is going to be.So not quite as catchy and thegradient needs to be muchsteeper for it to work than inthe low friction Infinity Trainexample, the manufacturersuggests with about a 10%gradient, it won't ever need tobe charged, so that would limitit to pretty short steep routes.On long routes, you'd need abigger battery and the batteryin the e-Dumper is alreadynearly 5% of the unloaded trucksmass. On less steep routes, theratio of gravitational potentialenergy to the friction losseswould skew in favor of friction.So you need top up charging. Sowhilst regenerative braking is agreat technology that makes EVsall kinds much more efficient, Idon't think we'll be able to doaway with charging altogether inany more than a few use cases.The calculations I've done inthis video are all based onreally simple physics. If youwant to see what the effect ofmore accurate or differentassumptions are, then it's veryeasy for you to do that. And ifyou need more help to getcomfortable with the physicsthen Brilliant can help you out,they're the sponsor of thisvideo. Brilliant is a websiteand app with over 60 interactivecourses in math, science andrelated topics like engineering.They have interactive courses onall the basic physics principlesthat I use today. And if youwant to dig deeper into some ofthe factors that I only guessedat, like say if you want to knowhow to estimate the aerodynamicdrag, the course for that wasone I particularly liked becauseit uses the example of adownhill skier. Theinteractivity and everydayexamples are some of the bestthings about Brilliant. Youlearn by doing, not justmemorising and then you applythe concepts to familiarexamples. This helps you developan intuitive understanding ofhow the world works. You can getstarted on Brilliant for freeand for Engineering with Rosieviewers, Brilliant is offering20% off an annual subscriptionfor the first 200 viewers tosign up. You just need to go tobrilliant.org/EngineeringwithRosieand I'll put the link in thedescription. So a big thanks toBrilliant for sponsoring thisvideo. And thanks also toeveryone in the Engineering withRosie Patreon team who, youknow, they sponsor every videothat I do. If you want to joinus and support the channel, haveinput on the future directionand access our Patreon-onlyDiscord server then you can joinus at this link. Thanks forwatching, and I'll see you inthe next video.\n"
