Comment by larsnystrom
5 years ago
In a few decades the internal combustion engine will be to transportation what the typewriter is to typing today. It’s kind of mind boggling, but there is really no alternative if we want to stop increasing the CO2 concentration in our atmosphere.
Hmm... Hard to beat that energy density when the workload is large.
Trucks, tractors, planes, ships. Sure consumer cars will be EV but ICEs are not going anywhere
This sparked my curiosity...
Currently gasoline has about 50x more energy per unit weight than a tesla battery pack.
Battery energy densities have tripled in the past 10 years. Keeping on that pace, it would take over 30 years for batteries to be competitive with gas.
When you account for the astoundingly bad efficiency of ICE, though, the gap in usable energy decreases. This is why a tesla can go 300+ miles with a battery that can only store the same energy as 2.4 gallons of gas.
You're likely to hit a hard limit to what battery energy density can reach. The next step will be fuel cells which don't have the efficiency limits of traditional internal combustion.
The Tesla can go 300 miles by making it light, aerodynamic, brakes that recharge the battery, not turning on the heater, etc. Yes, it's a significant engineering accomplishment, but in the heavy long haul world when analyzing break-even points what matters is range improvements due to an increasing energy/weight ratio, not range improvements due to reducing air resistance and inertia. This is because the form factors of the boxcar are basically set by shipping container needs and the weight is going to be determined by the load you are carrying. Munro is advocating for hydrogen powered trucks and planes as hydrogen has similar power/weight characteristics to gas -- electrification of these is going to be a challenge.
4 replies →
People have hard time grasping how much energy chemical bonds can hold. 15 gallons of gasoline store 500kWh of energy. That is 5 tesla model s worth of energy.
Efficiency plays role for our day to day car tasks, but when you have to deal with external forces or higher requirements of momentum, then you need more energy period. Towing, beating high-speed drag / waves, climbing high, cannot be addressed with smarter design. You need to be able to store somehow enough energy to deal with these external forces / additional required momentum
> 15 gallons of gasoline store 500kWh of energy. That is 5 tesla model s worth of energy.
Yes. However, the Carnot efficiency means that most of it is lost as heat. Suddenly the advantage is not that large anymore.
1 reply →
Don’t forget to talk about rockets! Although there weight is more important than volume.
Volume matters too, especially for lower stages. There's a reason for the lack of success of hydrolox 1st stages.
ICEVs will outlast BEVs. Just like it did 100 years ago.
ICEVs will outlast BEVs. Just like it did 100 years ago.
Hydrogen works fine in ICEs with modest modifications.
Hydrogen can be created with nearly any energy source: renewable, natural gas, etc.
There is a large infrastructure for moving fuels.
>Hydrogen works fine in ICEs with modest modifications.
Just that they get lower efficiency than a fuel cell version, and apparently are sensitive to load, so mostly suited to constant-load applications, which a car typically isn't. Otherwise it'd have been interesting as fuel cells also have some serious drawbacks and seem to develop very slowly.
> Hydrogen can be created with nearly any energy source: renewable, natural gas, etc.
Yes. Although efficiency is kind of bad, so it doesn't make sense to use fossil fuels to make H2 for cars - we'd just be increasing emissions as opposed to generating electricity for use in BEVs. H2 has its place as intermediate term (before batteries get cheap enough) energy storage of surplus wind and solar power. It makes more sense to use the H2 for other things than cars though - ships, trains, long-haul trucks, possibly planes.
>There is a large infrastructure for moving fuels.
Which I bet has to be seriously adapted to handle hydrogen. You wouldn't be able to move syrup with the existing infrastructure, because it's very different to gasoline. H2 is probably a lot more different - it needs much tighter seals, it embrittles materials such as steel, which is used everywhere for e.g. gasoline storage. It is cryogenic and under high pressure. Finally, it'd be stupid to lock ourselves into an energy storage tech that relies on a physical fuel that has to be transported around, when electricity is right there, partly built out already and requiring no physical trucks, trains, boats etc to get to the consumer. It's just stone age and the only reasons people think it sounds like a good idea is that they're so used to it working that way.
I wouldn't be so sure, I think there's a decent chance that e-fuel can be made economically viable.
Pure EVs will reach a fundamental peak percentage similar to any other car class... Hybrid powertrains are really where the next 20-30 years are headed for the bulk of vehicles. Automotive racing and supercars have demonstrated hybrids are the most effective setup for the past decade, and barring some major breakthrough in battery tech that will all trickle down into consumer cars over the next 0-20 years.
> Hybrid powertrains are really where the next 20-30 years are headed for the bulk of vehicles
It depends what you mean by 'bulk'. I see a major future here for big trucks-- right now, 99%+ of our long-haul tractor trailer semis are pure ICE. There is no way to fully electrify that fleet quickly, so I believe hybrid tech is being seriously underestimated in this space (especially for retrofitting).
I've been expecting to see this emerge for over 5 years, I'm not sure what's taking so long. Likely it's a catch-22 of the industry being resistant to change, while large chunks of (reluctant) investor funded R&D are necessary to make it viable. In any case, I think some larger scale tests are finally being run this year, so I'm looking forward to the results of that.
As far as consumer vehicles go, well... we should electrify almost all of it. Simply the best choice for the majority of use cases. But that's going to take a while, and will affect battery availability, which is all the more reason why big trucks will need a longer transition phase that hybrids are perfect for.
As soon as governments get serious about CO2 emissions, Hybrid powertrains will end up as a "worst of both worlds" position.
Already across most of Europe all subsidies and discounts that applied for "eco friendly cars" no longer apply to Hybrids.
That leaves few people wanting to buy a hybrid - it won't be cheapest or most eco friendly.
Not sure I agree with that. I don't think you realize how many cars have switched over to hybrid powertrains, but are not advertised as a main selling point like the Prius or Volt. Volvo's entire lineup is now hybrid or electric along with their new performance brand Polestar. Mercedes is switching over to hybrid powertrains even on their AMG models. Audi's using hybrid powertrains even on their highest performance models like the RS6 and their ultra luxury vehicles like the A8. Hybrid technology is great for sports cars and offers many advantages over fully electric, most importantly being the weight savings.
1 reply →
I think the thinking on hybrids will shift from "smaller gas engine with an electric boost to help with merging on the highway" to "range extension option for the electric car." They'll be configured to not even fire up the gas engine until the battery pack is run down enough.
Hybrids are facing real challengers from a combination of PHEV, synfuel, hydrogen combustion and hydrogen fuel cell. While it is the ideal car of today I wouldn't be so sure about the next 20-30 years.