271–275 of 275 posts
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And yet, electric cars you can by today don’t have 1/16th the range of a gasoline car. So energy density is not enough.
Not enough for what? The energy densities of both LiPo batteries and gasoline are enough to make a passenger vehicle with an acceptable range. For gasoline it is more than enough and for LiPo it’s barely enough.
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A Tesla Model 3 has 1060 pounds of batteries. If you replace those with a 177 gallon gas tank (at 6 lbs/gal) you should be able to go 4,780 miles at 27 MPG. It’s just that nobody wants to give up that much volume (visualize a 6x6x5 cube of gallon milk jugs). I’m not accounting for a gas engine having more heavy parts, that mostly matters in city driving.
27 MPG is abysmal. The 2024 Prius gets over 50 MPG so it could be closer to a 10,000 mile range.
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The mention of air travel was strange. I wasn't aware of anyone who thought long range flight would ever be electrified. At least not without some fundamental breakthrough. S-curves are hard to predict. Basically every time someone attempts to do it, they are way off. This [0] is a neat paper that addresses the question. We've blown past every single prediction. [0] https://www.inet.ox.ac.uk/files/energy_transition_p…
Can we use excess solar energy to create synthetic fuel (hydrogen?) to power jets? I know almost nothing about this space. I would appreciate a comment on why this is feasible or not...
Companies like terraform industries are doing something similar, but creating natural gas. With enough cheap solar, all hydrocarbons are pretty much on the table as well.
It'll be a decade or more until this is scaled up and not dependent on subsidies.
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Diesel is more like 3.175 (25%) due to the inefficiencies of small heat engines. You're throwing away like 3/4 of the energy as waste heat. Electric motors are >95% efficient and lithium batteries are in the high-90s percent efficient. Electricity is already low-entropy, whereas energy from burning petrol is high entropy and thus contains less useful work.
Diesel has efficiency of 40% not 25%.
- Diesel has a peak efficiency of 40% but an average efficiency of 20-25% (depending on the type of driving)
- Gasoline has a peak of 35% and an average of 16%–20%
- Battery has a peak of 85% and an average of 80%
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Kind of unrelated, but I'm wondering why TX uses so much more electricity than CA. Right now (afternoon of 1/26) happens to be a good time to compare: -- Temperatures are mild throughout most of TX (50s and 60s F); temps in CA are similar, perhaps a bit warmer; -- It's roughly mid-day in both places (3PM TX, 1PM CA); -- TX has a population of ~30M, CA has ~39M ..yet somehow right now TX is consuming ~47GW (per ercot)…
It's a mix of a bunch of things. CA is more heating day dominated than TX, and as a result of that, more households use natural gas for heating, whereas you're more likely to see supplemental electric heat in TX than, particularly, NorCal. (2) high energy costs lead to more investment in electrical efficiency in CA; (3) high energy costs mean that if you're running an aluminum smelter (for example), you don't run it…
But what Texas has is much higher requirements for air conditioning, which can't be easily gas-powered at the level of individual houses. Thus the higher electrical energy requirements. Now, you can run gas turbines at the utility level to generate electricity, but that's much less common at the level of individual homes.