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The inconvenient truth about Tesla’s Semi
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11-17-2017, 01:52 PM | #1 |
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The inconvenient truth about Tesla’s Semi
This is from the National Post and is part of an ongoing series of articles regarding EV's, the writer is an electrical engineer and has been labelled "anti EV" by his critics, from what I read of his material though, he sounds more like he's just asking or pointing out serious questions and issues.
Tesla has finally unveiled its much-promised big rig. And with not a little fanfare, especially considering that said semi is claimed to have a range of 500 miles (800 kilometres!) and, more importantly — at least for fleets seriously considering an all-electric 18-wheeled future — is able to recharge 400 of those miles (640 km) in just 30 minutes. So the question is, has The Elon Musk really reinvented the electric vehicle yet again? Or are his latest claims of re-imagining heavy-duty transport just more of his Madoffian fantasy? To find out, Motor Mouth broke out the old calculator — OK, my new iPhone 8; one must be au courante, after all — and used those few numbers Musk was willing to share to in order to try to shed some light on some claims that would seem to be the death knell of the diesel truck. The most important calculation, of course, is what Musk’s semi has under the hood — battery-wise that is, not engine — since what we all want to know is how many kilowatt-hours Musk imagines it takes to get a truck that may weigh as much as 80,000 pounds fully loaded to travel 500 miles on a single charge. Plugging what we know — 30 minutes of recharging time and the fact that the biggest recharger available is 600 kilowatts — into some fairly simple formulae and we arrive at a number that says Musk estimates his sleek semi will require about 300 kilowatt-hours to travel 400 miles.  Now, here’s where those numbers go just slightly awry. Mr. Musk’s sleek Model S — a bit of a porker but aerodynamically efficient nonetheless — needs just a hair under 0.33 kilowatt-hours to travel one mile. So, if it, too, were to claim a 400-mile range, it would need about a 135 kW-h battery. Now, I am pretty sure that it doesn’t take a degree in rocket science to figure out that one of those calculations — a Model S needing 135 kW-hr to travel 400 miles or a full-sized 18-wheeler requiring just 300 kW-hr to do the same — is a little wonky. The truck is, after all, about 15 times heavier and probably has at least three times the aerodynamic resistance. For those needing a little more arithmetic backup, consider the following: A current, fully-loaded 18-wheeler similar in shape and size to Tesla’s big rig can consume anywhere between 40 and 50 litres of diesel fuel per 100 kilometres while cruising at about 100 kilometres an hour. By way of comparison, an Audi A7 — similar in size and shape to a Model S, but also diesel powered — consumes about 6 L/100 km. And that’s with your humble Motor Mouth hogging the fast lane at about 120 km/h. Simple math, then, says that said ginourmous truck consumes somewhere in the vicinity of six to eight times more fuel to cover the same distance than the itty, bitty car. As further comparator, big rigs can use up 10 times as much horsepower to cruise at 100 km/h as a car, but we’ll stick with the more conservative estimate of six to eight for our calculations. f we use the median of those figures and assume that Musk’s truck requires eight times the battery as his Model S to cover the same distance, then, that 500-mile range he claims requires somewhere around 1,000 kW-h to power. At current prices, the batteries alone could cost as much as US$200,000, a figure that jives (roughly) with a recent Carnegie Mellon study on electric semi trucks that determined that “a 300-mile-capable battery pack costs about $200,000.” An entire diesel truck, by way of comparison, costs about US$120,000. That same study also estimates that the battery required for a long-distance big rig could weigh as much as as 22 tons — in other words, according to the study, the truck’s battery is heavier than its payload. More dramatically, plugging those numbers — 1,000 kW-h rechargeable in 30 minutes — into those same basic recharging calculations tells us a 2 MW (yes, two megawatts!) charger would be required to replenish the new Tesla 18-wheeler in the time Musk claims. That, as they say, is a game changer, since the 0.6 MW unit I mentioned earlier is so powerful it needs to be fully automated, is about the size of a small gas station kiosk and costs in the range of half a million bucks. And, lest you think I am being overly harsh with my estimations, that aforementioned Carnegie Mellon study (Evaluating the Potential of Platooning in Lowering the Required Performance metrics of Li-on Batteries to Enable Practical Electric Semi-Trucks) estimated that 1,000 kW-h would only generate 300 miles of range; so, in fact, Tesla’s proposed Megacharger might have to actually be larger than two megawatts if Tesla wants to recharge 400 miles in just 30 minutes. Unlike previous Motor Mouths regarding Mr. Musk’s claims, I will pass no judgment on whether these latest pronouncements are feasible or outrageous. I am, frankly, tired of his acolytes portraying me as anti-electric and, more insulting, anti-progress. I will, instead, simply offer these calculations as a starting point for discussion. Make of them what you will. |
11-17-2017, 04:11 PM | #2 |
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The reasons why people buy a Tesla car is because of emotion: Its fast, its high tech, they want to save the environment.
The reason why trucking companies purchase trucks: bottom line. The only way this will work out for Tesla is if they can make the ROI trade out positive. Maybe they are banking on some commercial tax credits or something.
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11-17-2017, 04:18 PM | #3 |
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WHat's Diesel cost in Europe? $1.75ish a litre? Let's call it $1.50.
If said rig works 5 days per week, it's chewing through what, 150 to 200 litres a day according to the numbers above, so we call it 175 litres. So you're saving $1,500 per week on fuel less charging costs. NFI what they are but that's a saving of about $75,000 year on gas so even if this thing is twice as much as a regular rig, you'd recoup pretty fast. |
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11-17-2017, 04:24 PM | #4 |
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RABAUKE there's lots of legitimate questions about the actual impacts of EV's on the environment. There has been way too little study of the A-Z environmental impacts of battery production (including lithium and cobalt mining) to disposal. Worse, nowhere near enough analysis of the impact on carbon emissions of all the additional demands on the power grid. While coal is not the primary source for electric power anymore, I understand it to be the most prevalent source of marginal energy and therefore the primary supply point for all these EV's plugging into the grid. And there is no such thing as "clean coal".
Not only is David Booth right (again), we need to be embracing his viewpoint and using it to fuel (pun intended) a legitimate debate about the merits of EV's. Right now, it seems that everyone is afraid to point out Elon Musk for what he's peddling: a modern incarnation of Clark Stanley's Snake Oil Linament. This week's announcement was nothing more than the latest stop on his medicine show tour. |
11-17-2017, 04:41 PM | #5 |
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I don't think comparing fossil fuel consumption with energy consumption is equivalent at all. Once a big rig is going, it has a lot of momentum that would most likely help (and be taken into consideration to put out a bigger number).
I haven't seen many (any?) tesla vehicles fall short of Musk claims yet, I would place money on Musk's word over some guy's sloppy math.
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11-17-2017, 04:43 PM | #6 | |
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11-17-2017, 05:34 PM | #8 |
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The math comparing petro chemicals to EVs always seems absurdly deficient. I've seen very few studies compare battery creation to finished car compared to crude extraction, shipping, refining and retail costs, plus the cost and resources of creating an engine, lubricating and cooling system and the additional ongoing consumption of those things for the non EV.
It's all well and good to understand the substantial negatives of mining and creating heavy metal batteries primarily in China, but you have to weigh the trade off to crude coming from Saudi Arabia, Venezuela and our new found friends the Russkies, and if we want to consider our other primary imported oil, the Canadian tar oil isn't exactly going to win any environmental comparisons either. |
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11-17-2017, 06:02 PM | #9 |
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At least these federal subsidies result in a tangible commodity for the consumer and have actually pushed the solar, EV, and space technologies forward. How many other federal subsidies can say the same? These programs exist for a reason. The advancement on EV technology in the past 10 years have been significantly bolstered by the existence of Tesla both by their own innovations and the creation of real competition in the automotive industry marketplace. The Bolt and the Volt would not have been made if not for the competition Tesla has provided as both a competitor and market motivator. That's actually what the subsidies are supposed to do: stimulate.
BTW there is WAY too much speculation in the original post to come to any real conclusion. If Musk delivers, then the argument is for nothing. If he doesn't deliver, what did we accomplish except a "told you so"? Who want's to be that person? We should be hopeful that Tesla delivers on the promise and can actually contribute something that will improve our way of life in some way. Being a cynic at this point is for the sake of our egos and nothing more. Wishing to be in the position of saying "I told you so" at the expense of actual progress is selfish and shortsighted. What kind of world would we live in if cynics of things that could benefit us were always proven right?
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11-17-2017, 07:30 PM | #10 | |
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Well I think healthy debate and discussion is important given the commitments our governments are making with our tax dollars and the push by some governments to ban ICE moving forward. |
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11-17-2017, 07:55 PM | #11 | |
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Now, if it's not, then there is a discussion to be made. However, those subsidies are not attached with stipulations for a successful semi truck that meets x y, and z requirements outside for what the subsidies were designed to do: stimulate sector growth. Even if the semi's fall short, they are one step closer than before they existed. Do you think the first automobile ever invented was 425hp and got 26mpg? Progress starts with the first step. I understand you want to debate and discuss "tax dollars", but if you are planning to use the success or failure of the Tesla Semi as a barometer for the effectiveness of federal subsidies in the EV sector, then honestly I think you have the wrong idea of what these subsidies were created for. The government will not ban the ICE if the overall EV sector does not deliver. If they deliver what is needed for our infrastructure to survive and thrive, then it is a possibility. However, what they will NOT do is make a decision to ban or not ban the ICE on what Tesla claims their product will do. It will make those decisions based on what they actually do once produced and delivered. And even in that case, it will not be Tesla alone, it will be every manufacturer in the world who has a product for this sector and what their role it in will be. It's a bit premature to even talk about banning the ICE, whether you are for or against it. It's kind of like talking about and debating whether or not to bring an umbrella outside tomorrow. Will it rain? Will it not? You know what, lets just look outside when we are about to leave and pick up the umbrella on the way out the door. Why have a debate about it a day before? Honestly, I think it's just an excuse for people to, once again, complain about where their "tax dollars" are going. Hipster electric cars and environmentalist snowflakes are much easier to fixate on then the MIC. edit: You are right though, you should be able to discuss them if you wish. I question some people's motivation, however, when they talk about "tax dollars" yet don't seem to know what the proportions of allocations are.
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11-17-2017, 08:12 PM | #12 | |
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11-17-2017, 09:20 PM | #13 |
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What's missing is the true environmental impact of EV's. Three issues that are completely overlooked: environmental damage from lithium and cobalt extraction/production (everyone just talks about disposal); other environmental impacts such as increased acid rain; and, the substantial increase in carbon emissions from all the coal necessary to fuel the charging network for EV's.
From the MIT Technology Review: A 2007 study by the Pacific Northwest National Laboratory found that without adding a new plant or transmission line, the U.S. grid could reliably charge 84 percent of the nation’s cars, pickups, and SUVs. And, The vehicles will only be as clean as the power sources used to charge them, and more than 80 percent of U.S. energy generation still comes from fossil fuels. I've seen several other references to the same issue. Until credible research organizations (like MIT or any of the other Top 35 Universities) actually give a thorough assessment of the entire environmental picture associated with EV's, as a society we're insane to be blindly pursuing the dream of Hamlin’s Wizard Oil Company as presented by Elon Musk. |
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11-17-2017, 10:09 PM | #14 | |
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If electric car impact was so bad, you can bet oil companies would already be advertising, as their business have huge $$$ on the line. And as for credible research, most "independent" research is very hard to come by as it will only go as far as their sponsors allow it. |
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11-17-2017, 10:17 PM | #15 | |
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Until there's credible research into the subject, WTF are we doing? |
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11-17-2017, 11:05 PM | #16 |
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I have one basic issue with the whole EV concept.
In terms of simple physics, would you rather burn some fossil fuel in your ICE vehicle to power it and suffer minor energy loss as compared to the situation where you are burning the same fossil fuel to power the turbine to create the electricity to charge the battery to power your EV? I mean it makes no sense at all if you look at it this way, does it? How is it better, cheaper, more efficient, cleaner... whatever??? I mean to most ordinary people electricity looks like a clean, cheap and abundant energy source - you just plug something in and voila - magic! Seriously, I think this is how they are trying to sell this entire EV concept to people. Like they just don't know any better and will buy into yet another scam as long as it is a cool and responsible and politically correct thing to do. It's all about the "environment", you know. But if you ask an ordinary person, they would not even know the definition of the word, I bet. The one thing that is certain is that your battery pack will degrade over time and your range will decrease until your car becomes a lawn ornament and you will only be driving it as far as your plug-in cord will reach. Just like that laptop you bought five years ago. I thing this will ensure that cars become truly disposable with an expiry date set by the battery pack, and that is how you do business ladies and gentlemen, thank you. Last edited by vinylengraver; 11-17-2017 at 11:19 PM.. |
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11-18-2017, 01:32 AM | #17 | |
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So, purely from a practical standpoint, we need to find alternative fuels to coal, oil, and gas. What do we have so far? Solar, wind, hydroelectric, nuclear, and smaller groups of things like hydrogen, vegetable oil etc. The key here is that, besides hydrogen and vegetable oil, none of these sources are capable of being stored in the car unless it contains a battery. Hence the need for an electric car. 95% of hydrogen is made in a process that uses natural gas. You can make it with solar, wind, etc, but the cost is high and the energy content per unit volume is low. Might as well just use that same power to store it in a battery for the car directly. Besides, you have to transport that hydrogen to the customer, so it's even less fuel efficient. So, unless we find a better way to produce and deliver hydrogen, the electric car is still the best bet. Will our current infrastructure support the EV? Not yet, but it has to simply because it's going to be the only option once ICEs run out of fuel to power them. Adversity breeds innovation. The dwindling supply of fossil fuels is the adversity, the innovation is the EV. Quite simply, it's the only logical step. Imagine it's 1886 and everyone is riding horses and carriages to get from point A to B. The morning edition reports of a fuel driven automobile. You started telling everyone that the automobile will never survive because there are not enough gas stations to get anywhere outside the major cities. Imagine how foolish that 1886 person looks to us here in 2017. Now imagine it's 2148 and someone is reading your post. How will you look to them?
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11-18-2017, 01:44 AM | #18 | |||
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2) Electric current is transported over a wire. Much much less fuel burnt. 3) The point of the EV is to replace non-renewable fuel sources like oil, coal and gas. When those thing are gone in 200+ years, the first and second scenario won't be possible anyway. Unless there is another substance that can be stored on our car to be turned into heat for the ICE, then we need another way to store energy on our cars to use to drive the wheels. What could be possibly use to store energy?!?!?!? Um... a battery. What will generate the power to full our batteries if there are no more fossil fuels? Wind, solar, hydro... Nuclear? They will have to, what other choice do we have? Quote:
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11-19-2017, 12:40 AM | #19 | |
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Thermodynamic efficiency, since you speak of physics, you should look up some of this stuff. The power source of choice for many urban areas now are turbine power generators. They are scaleable and can be added easily when the power demand increases and they are relatively easy to construct and maintain. The most efficient have eclipsed 65% and just a few decades ago, it was thought that 50% efficiency was a barrier. There are of course transmission losses, but this still beats out ICE engines, which are thermodynamically limited, being more around 20%, again with all that stuff banging around and having run fuel pumps and everything else, it's not hard to understand. Then of course, there's the infrastructure to run all of your ICE, from the huge supertankers that have to ship the crude, the ports that have to service them, to the refineries that have to crack the crude, to the storage bunkers that have to be constructed, to the ships and pipelines that have to be constructed to ship the fuel, to the stations that eventually get it, it's an immense cost and consumes a huge amount of energy, not just to transport it, but to make all this stuff that is required to transport and store it, which is ultimately takes fuel. Although there isn't full electrical infrastructure at this time, it wouldn't require constantly shipping fuel everywhere and many of these costs. Fossil fuels will be with us for a long time, there's no doubt about that, but already physics and science shows us that it's cheaper and more efficient to burn the fuel at a location that can harness much higher efficiency, then beam it out to remote locations for use in electric engines. I mean, that's almost the point of every single electric engine used anywhere, otherwise we'd have gas engines doing ridiculous simple tasks that make no sense, like a gasoline powered car-wash, or gas-powered shop tools. The problem with electric has always been storing the kind of energy density that makes it practical, to which we are finally seeing some practical and useful progress.
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11-19-2017, 12:45 AM | #20 |
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Hey Rabauke, your only contribution on this board are to stir some bad press on Tesla. Do you have some disclosure to make about working for a gas company, another manufacturer, or the heritage fondation or something like that ?
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11-19-2017, 01:06 AM | #21 |
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I would agree that Tesla walks a fine line between delivering and inflating their stock, but I think they are unquestionably pushing technology in many areas, they have to play that balance carefully of sticking their fingers into too many things. As someone who grew up with the promise of electric cars, only to see a few poor attempts fail, the Model S is an amazing achievement. Some people seem to irrationally hate EVs, but it's out there working for many people in many locations, I see Model Xs around too. I live in Alaska and I freaking see these things, again, that is amazing to me. Whining about not being able to afford one or not being able to buy an extra car just to have one is pretty weak IMO, you could also go buy a horse when the first horseless carriage came out.
Tesla needs to produce the Model 3, there is no question, they can't obfuscate with all this other stuff, but if they deliver and can do all of this, it's going to be a pretty bright future for EVs. Even though I have no use for them in the near future, I don't irrationally hate them as some people seem to. I don't know if these people feel this way because they are programmed to do so based on what they listen to/read/hear, but being somewhat familiar with science, there are too many advantages to not pursue the technology.
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11-19-2017, 07:44 AM | #22 | |
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It occurs to me that some governments are going to outright ban ICE in the next decade or so, and given my earlier mentioned age and questioning of things, and I'll throw in that my job had me imbedded in government for a significant period of time that i don't trust that governments have the answers to all of these questions but they will stuff their solution down our throats any way. |
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