The billionaires are fighting. Bill Gates and Elon Musk have a history of bickering, with Gates suggesting Musk stick to rockets and electric cars rather than spreading his contrarian ideas about coronavirus. Musk replies "hey, knucklehead, we actually make the vaccine machines for CureVac, that company you're invested in" in a podcast interview.
I didn't look into that dispute, but I followed up on a disagreement about electric trucks. In his blog post How do we move around in a zero-carbon world? Gates casts aspersions on electric trucks, such as the Tesla Semi.
- EVs excel at short-haul travel. That means they’re great options for personal cars and even medium-duty vehicles, like city buses and garbage trucks. But even if we develop cheap, long-range EVs that are powered by zero-carbon sources, electrification isn’t an option for many types of transportation.
The problem is that batteries are big and heavy. The more weight you’re trying to move, the more batteries you need to power the vehicle. But the more batteries you use, the more weight you add—and the more power you need. Even with big breakthroughs in battery technology, electric vehicles will probably never be a practical solution for things like 18-wheelers, cargo ships, and passenger jets. Electricity works when you need to cover short distances, but we need a different solution for heavy, long-haul vehicles.
Musk replied, "He has no clue".
Who's right? Engineers in the house, please chime in.
I note that Gates says that batteries are "big and heavy" but then never mentions size again. For a vehicle that is already quite large, increasing the size by adding bulky batteries seems like a minor concern. Among 18-wheeler trucks, there is already a wide variety of tractor size. Some have a sleeping compartment in the cab.
What about weight? Gates says "the more batteries you use, the more weight you add—and the more power you need" but power for what? A heavy battery in a truck on the ground needs no power to continue existing. This is true when the vehicle is parked or in motion. At highway speed, air resistance is the main force that the engine has to overcome.
Extra battery weight is a factor in getting up to speed. Force equals mass times acceleration, so if the mass of the vehicle doubles, the same engine force will accelerate the truck half as fast. Semi truck 0-60 mph times seem to be about a minute. Compared to the many hours of a long-haul voyage, adding a minute or two to get up to speed is no big deal.
Gates hints at a runaway problem of more battery weight requiring more batteries causing more weight, familiar to Kerbal Space Program players who keep strapping more boosters on their rocket. But a rocket fighting gravity is very disadvantaged compared to a rolling vehicle getting up to speed and overcoming drag. Aircraft also fight gravity, and I think Musk would agree that electric flight is still far off.
The Model S battery pack weighs 540 kg, 24% to 27% of the total weight of the car. It seems to me that these numbers could be scaled up to truck size without much affecting the ratio, with plenty of apparent room for a higher battery composition.
Stopping is a factor too, and heavier vehicles take longer to decelerate. This is already an issue that trucks carrying heavy loads have to contend with, but batteries will probably weigh more per unit of energy output than gasoline for a while. On the other hand, regenerative braking can recover some of the energy used to accelerate the vehicle. This is a big advantage in hills, where diesel trucks use fuel going up and brake pads going down.
- Electricity works when you need to cover short distances, but we need a different solution for heavy, long-haul vehicles.
Almost all of the largest locomotives have electric motive power. Battery-electric locomotives are in development now.
I score this dispute in favor of Musk.
I am with Bill on this one. Fortunately informed by a few years as a logistics manager. For Heavy Goods Vehicles at cruising speed there are two major resistances that need power to maintain speed: Air drag and Rolling resistance. Drag is independent of weight but is typically a quarter of the effect of rolling resistance which is proportional to weight. So heavy batteries will drive up your overall power demands per tonne-km moved. Acceleration is rather a small part of a long distance trucks overall energy needs so can be ignored. Trains are a different story. Rolling resistance is negligible as steel on steel has a very low rolling coefficient, so you can pile on the heavy battery packs with little impact on performance.
Thanks for weighing in. I am surprised that rolling resistance is that much higher than drag, especially after learning that 18-wheeler tires are inflated over 100 PSI. In practice, any transition toward electric trucking will be gradual, with short hauls of lighter cargo in more developed areas converting sooner. Logistics seems like an interesting field. I just started reading The Box.
I'll preface this by saying that I'm not nearly as bullish on EVs as is popular these days. Gates is definitely right that batteries are heavy--I think a model S weighs as much or more than a full size pickup. However, he is making a mistake by thinking that all the power needs to be on board at the start of the trip. It's not as if an 18-wheeler carries all the diesel it needs to go from LA to Chicago without stopping. They fuel up. And that's easy with diesel, because distribution is widespread and delivery is easy with a pump. Batteries obviously can't be charged quickly even with a "super charger" or whatever. But I think that there are probably ways around that (e.g. modular batteries, super high voltage chargers, etc). However, each of those solutions, while probably technically feasible, will require a lot of infrastructure to realize. And if the industry is smart, they will work together to try to make scalable solutions that work across platforms. There's no such thing as a Toyota gas station or a Volvo diesel station, and we wouldn't tolerate it if there was. So I think Gates is correct in the short term, but he could be wrong were the technology to advance to a point where it's no more burdensome to use electric than diesel or gas.
No, there are no Toyota or Volvo gas stations. But in the trucking industry they have Love's, and Stallion, and others. These are enormous truck service centers that are equipped to work on any vehicle that drives into their lot, and have amazing logistics networks for parts and equipment, as well as direct access to OEMs and their production line output. Manufacturers keep these service chains happy. Otherwise their brand vehicle sits parked in the lot, like a big billboard of failure that all the truckers can see. I know they are already looking at stocking replacement battery packs to recharge long-distance trucks. Pull in, swap your battery pack, and drive off 30 minutes later after you get a piece of pie and fresh coffee.
I agree with you. I think if we're trying to pick who is right and who is wrong and who is wrong but in a useful way, Gates is right short term, and the technology (including economic viability of technology) is unavailable to prove him wrong. By not relying on future advances he may help inspire alternative approaches. If Musk is right it isn't because he's already right it's because he's banking on future advances. So I put Gates between right and wrong but in a useful way and put Musk between potentially right but not usefully so and wrong and in a potentially harmful way (by discouraging alternate views). So I think Gates is correct in the short term, but he could be wrong were the technology to advance to a point where it's no more burdensome to use electric than diesel or gas.
AFAIK most electric motive locomotives use diesel engines to turn a generator to produce the electricity. Electric motors have fantastic torque, which is great for pulling heavy and slow. Drag is very important at high speed, as drag increases as the square of the velocity. This quickly becomes the dominant factor in terms of energy expended than getting to speed if you are traveling fast and far. This is why cars all look like lozenges these days. Maybe if there was a slow lane for EV semis? But then you have a train... I am not an engineer, but electric motors lose torque at higher RPMs, whereas engines reach peak torque at higher RPMs. This may be another reason why ICEs are better for long haul trucks. They produce more torque at high speeds. I'd like to know if this is a important factor. I believe Tesla sedans are direct-drive, so they aren't gearing to compensate for this in the cars. Not sure about their Semi. Finally, and perhaps most importantly, the energy density of gasoline is much higher than batteries, so even though the engine might be 1/3 as efficient, it has the luxury of a very efficient fuel.At highway speed, air resistance is the main force that the engine has to overcome.
One of the things that is rarely appreciated about batteries is that they can't, by the inviolable laws of thermodynamics, be more efficient than the energy source that was used to produce them. So while you might be able to get more energy of out of battery on a percentage basis than you could out of an IC engine, when you consider where that energy came from in the first place (typically fossil), they are less efficient, full stop. Unless or until we use renewables, EVs are worse for the environment, even though they have zero tailpipe emissions. I want to key every Tesla I see in MI that has a ZROCO2 vanity plate. In MI, and in most states, your EV power is coming from coal and natural gas.
Totally. Of course, there are many factors that go into the balance: gasoline vs. electricity delivery, refining and transportation of the required fossil fuels, etc. I wish our scientific literacy were higher, or at least the effort being made, if only to produce a scientific humility that we lack. Musk effectively arbitrages the difference between people's scientific literacy and science. It's part of his genius. I think a self-driving Tesla has been just 2-3 years out for 4-5 years now. In fact, he might be more futurist than industrialist. 2019 vehicle sales: GM: 7.7M Ford: 5.3M Tesla: 0.37M Marketcap: GM: $43B Ford: $27B Tesla: $400B Musk is not selling cars, as much as he is selling the selling of cars.
I didn't listen to the interview, but apparently he reminded the audience that he said Tesla was overvalued back in May (when the stock was one third of its present value) and also that it would be worth more in five years. It's easy to say now, but I think comparing Tesla to other carmakers is akin to comparing early Amazon to other bookstores. There's a vision priced into the stock. If the vision fails, it will be a dud like pets.com, but it's too early to say.
One thing I'll give him credit for is the acceleration of EV platforms at other companies. Definitely the EV industry wouldn't be where it is without Tesla. I think Tesla's market dominance in EVs is probably going to be short lived when, e.g., BMW, Audi, and other car makers who make cars that aren't ugly and rife with quality issues have viable products at competitive prices. Right now that giant market cap gives Tesla a big leg up on the competition by making them able to sell cars at a loss while still raising money whenever Elon feels like buying a new plane or whatever.Musk is not selling cars, as much as he is selling the selling of cars.
The first time I read this I nodded in agreement, but on reflection I don't understand what you mean. If by "produce" you mean manufacture, it is certainly possible to imagine arbitrarily inefficient ways to make batteries. You could mine asteroids for raw materials, for example. I think you mean that it is always better to connect a load directly to an electricity generator rather than to use the generator to charge a battery and then use the battery to carry the load. The charge/discharge process will necessarily have costs, though one old analysis suggests that lithium-ion batteries have charge/discharge efficiency of 80-90%, and more recent sources say "close to unity." But the whole point of batteries is to store energy for use when the generator is not available, so this seems like a minor criticism. An advantage of electricity is that you can produce it in the most efficient way available at any time and place and the end user won't notice. The first time I saw a diesel/LPG dual-fuel car I was impressed at the ingenuity, but it didn't seem like a win for efficiency. The annoyingly smug Tesla vanity plates around here often have some variation of "N0 01L". WanderingEng tells me it's not really correct to say your electricity comes from any particular nearby power plant. If so, we are all around 63% fossil fuel, 20% nuclear, and 17.5% renewable.batteries ... can't, by the inviolable laws of thermodynamics, be more efficient than the energy source that was used to produce them
Good point, but big power plants are more efficient (thermal efficiency). So there is some reduction in energy emissions, just not as much. Maybe not enough to compensate for the emissions cost of new materials and mining battery materials.when you consider where that energy came from in the first place (typically fossil), they are less efficient, full stop. Unless or until we use renewables, EVs are worse for the environment, even though they have zero tailpipe emissions
The only published research I've seen about it (and I'm not in the field, I don't follow the field closely, so take that with a giant grain of salt) concluded that EVs contribute more CO2 than a comparable IC in the majority of places in the US. I don't remember the numbers, but they had it broken down by what percent of coal and natural gas it takes to break even. IIRC the only places in the country that passed the test were in the West where they have a large percentage of solar and hydro. Obviously that should change over time as we integrate more renewables, but I was mostly just trying to point out that "EVs pollute less" has become sort of a heuristic for thinking green, when in reality the subject is complex. And it's more complicated by the fact that every asshole who owns a Tesla wants their car to go 0-60 in 3s, which, you know, takes the same amount of power whether it's gas or battery. "Gas guzzler" is such a pejorative lobbed at SUV/pickup drivers (and not without reason), but nobody who drives a sports car EV should get to use it. And yes, the mining and recycling of batteries is another topic that hasn't gotten a lot of attention that is also non-trivial. I only know enough to know that I don't know much about it. But my wife, who's well-placed at GM, tells me that it's one of those issues that Musk just says, "Fuck it, we'll figure it out later," while legacy companies worry about litigation and shit.
Interesting! The diesel-electric hybrid. My expectation was based on a trip on the Amtrak Crescent to Philadelphia. We stopped in Washington Union Station to change the diesel locomotives that had been in use since New Orleans to electric locomotives. The conductor told us the switch was due to air quality concerns in the northeast, and also the lack of infrastructure in the south. I also looked at the article about the second-most-powerful locomotive in the list, the 2ES10, since the #1 doesn't have an article yet. The photo shows overhead wires and there is no mention of diesel. I haven't found a good source showing how common the different engine types are. I also think Tesla motors are direct drive with no gearing. It seems like a good balance to have torque at low speeds for acceleration, and less torque at cruising speed when simply maintaining speed is more typical.AFAIK most electric motive locomotives use diesel engines to turn a generator to produce the electricity.
As a tangential addendum, here are two energy ideas I've thought of, but are probably completely impractical. 1. Solar-powered desalinization on the decks of tankers (maybe a skirt of around the deck). They produce fresh water, which they can sell at port, and use the very salty water produced to generate electricity on board using the gradient with sea water. 2. A Wankel engine/electric motor hybrid that has just one shaft.
Extra battery weight is a factor in getting up to speed. Force equals mass times acceleration, so if the mass of the vehicle doubles, the same engine force will accelerate the truck half as fast. Semi truck 0-60 mph times seem to be about a minute. Compared to the many hours of a long-haul voyage, adding a minute or two to get up to speed is no big deal. You fell prey to one of the classic blunders of Dynamics 101, conflating power and energy. Double the mass, and you double the acceleration time is power draw is the same. But energy to accelerate to speed al is also proportional to mass: energy = power draw × time = 1/2 × mass × velocity². And this increased energy cost isn't a one time thing, it applies every time you push the accelerator, every grade, every time someone cuts you off and you have to slow and regain speed. Electrifying freight trains is the probably the simplest technologically, its existing technology, assembled in a new configuration. Probably the hardest politically/legally though.What about weight? Gates says "the more batteries you use, the more weight you add—and the more power you need" but power for what? A heavy battery in a truck on the ground needs no power to continue existing. This is true when the vehicle is parked or in motion. At highway speed, air resistance is the main force that the engine has to overcome.
The simplest example of this, to me, is pro cyclists. They use the lightest bikes possible, and it's because every push, every grade takes less energy. Ride a heavy bike and it will wear you down over time more than a lighter bike.
Thanks for emphasizing this distinction. I barely scraped through Statics, so I appreciate the input. Gates is not very specific about why he is pessimistic about some EVs. I think he's right that converting from liquid fuel to batteries will increase overall mass. So that means more power while getting up to speed. More power means using energy faster, which introduces the range issue. If Gates thinks an electric garbage truck is okay, but not a long haul truck, it sounds like range is the main problem. But even without the "big breakthroughs in battery technology" that he rhetorically includes, it seems that you can just keep adding batteries to get the desired range (ignoring cost, which does require big breakthroughs). The volume of batteries seems likely to be small relative to large cargo movers, and the extra energy needed to move an additional unit of battery mass seems necessarily smaller than that provided by the battery.
My credentials: 1. I work directly with the development teams at DTNA - the arm of Daimler that makes Freightliner and Western Star trucks, as well as Thomas-Built school buses. 2. I just attended the School Transportation Summit (virtual) this week, where two of the presenters were Lion and Thomas-Built buses, showcasing their electric school buses. 3. And my company's customers include the two largest long-distance freight haulers in North America, Knight and Swift Trucking. That being established, the math/physics has already been laid out by the other posters on this thread, so I won't even dip my toe into the 'power vs energy' thing. I'll deal with the business end of things. Charging. School buses are a perfect model for electrification because they run established, pre-defined routes, and have long periods of inactivity throughout the day. Trucks are the exact opposite. They run for long hours in highly variable road, traffic, and weather conditions, which are all variables that affect battery efficiency. Plus, there are LOTS of trucks. And they can only stop in certain places. Getting enough voltage and amperage to a single location where 50 trucks are parked overnight and charging... that's a problem that cannot be solved, practically speaking. Cost. Yeah, everything comes down in cost over time. But. An electric school bus today is around 3x the price of an ICE-powered school bus. That is not in the budget for ANY school. HOWEVER... electric vehicles take almost no maintenance, every fungible part is replaceable, and could theoretically have an infinite(-ish) lifespan. Today's diesel school buses may run for 20-25 years, but they fall apart over time just due to wear and tear on drive systems. You can replace the motor and transmission so many times, before the entire vehicle just isn't worth saving. New electric buses have far fewer parts that get far less wear and tear, and every part can be replaced for a reasonable amount of money. You could possibly be operating the same electric school bus 50 years from now. It's a weird thing to consider... Infrastructure. A couple miles from my house, one of our largest customers has a vehicle yard with something like 600 school buses in it. They will need to be charged, if they move to electric. What is fascinating is that local power companies are working with school districts to install charging stations FOR FREE, so schools can charge their buses throughout the day. (Which is different than long-distance truckers, who generally need to charge at the same time of day, or can't/won't run on a partial charge.) But this is all VERY new. The business models are evolving, even over the last 2-3 months. People are throwing ideas at the wall and seeing what sticks, and thinking in really new ways about transportation. Thinking about Bridges vs Ferry Boats. Everything comes down to cost-benefit analyses. Sometimes it is better to build a bridge between two bodies of land separated by water, and sometimes a ferry boat is a better option. Here in Seattle, we have both. It is the consideration of all smart commercial fleet operators that electric will be a part of their fleet within the next year or two, and that portion will grow fast. Once you pull the trigger and get your first electric vehicle in your commercial fleet, the barriers to your second, third, ... and hundredth vehicle are gone. BUT. There will always(?) be ICE-powered vehicles in your fleet. Eventually they may be used only for special purposes (firefighting, emergency response, and other long-duty cycle operations), but fleet managers today know they will have electric vehicles in their fleet that they need to manage by 2022. Innovation. At some point, someone is going to invent a denser, longer-lived battery. They may already have one in testing, if recent news reports are to be believed. The big easy money for them will be to provide these in form factors where they can be fit into existing electric vehicles, to replace aging, failed, or less-efficient battery technologies. And it is WAY easier to drop in a new battery pack and controller than it is to replace an engine, transmission, and drivetrain to accommodate the latest Cummins/Detroit or other diesel engine. So fleet managers want to buy into an ELECTRIC PLATFORM, rather than a specific vehicle. Which is where I think Musk is really on the right track... an entire line of electric vehicle products, supported by manufacturing, that could churn out replacement battery packs for everything from a 1999 Honda Insight to a 2021 Thomas-Built Bus (which is named "Jouley", in fact), as well as their own line of vehicles.
Today’s trains, running on electricity produced at a remote power plant, are cheating a bit. They can still be coal-fired, but the coal and furnace are not on the train. A battery locomotive brings the power plant along. Take today’s heavy-duty electric train, remove half the cargo cars and replace with battery-filled cars. That should be plenty of energy for the long haul. There could be cost reasons why this is not feasible, but it doesn’t seem like an engineering impossibility.