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The comment said that solar powered trains would only be able to run at night if wind generation is sufficient to power them in the absence of solar power - at

The comment said that solar powered trains would only be able to run at night if wind generation is sufficient to power them in the absence of solar power - at least not without massive amounts of storage to account for this intermittency. Regardless, I'm not sure why the inability to detoxify waste is such a concern. First of all, we do have the ability to reclaim >95% of it through reprocessing. This isn't detoxification per-se, but does represent a sizeable reduction in the amount of waste. And the remaining waste is stored underground. The danger of uranium entering the water supply already exists from naturally occurring uranium. The additional risk presented by waste buried in a known location, with no groundwater contamination risk is zero. Sure, if you want to be pedantic, it's not exactly zero: some nefarious group could dig it up and use it as a weapon. But any group with that level of capability could easily deal more damage through conventional means - so for all intents and purposes the risk is zero.

kragen 6y ago
Aha, thanks for clearing that up. I think probably trains will have an easier time carrying batteries than electric cars do: a one-tonne diesel internal-combustion-engine car might get (in medieval units) 40 miles per gallon of fuel, while diesel freight trains routinely get 480 miles per tonne-gallon. Teslas need to recharge about every 500 miles, so we should expect battery-powered electric freight trains with the same battery mass fraction as a Tesla to need to swap batteries roughly every 6000 miles or 10000 km. A night train making it through the night isn't going to be a problem. If that's true, then why haven't batteries already replaced diesel engines in diesel-electric locomotives? I suspect it's a matter of battery costs and network effects. A gallon of diesel is 146 MJ, so a tonne-mile on a freight train costs 300 kJ, or 189 kJ/tonne/km in non-medieval units. Lead-acid batteries only give you roughly 20 kJ/US$, and low-power lithium-ion batteries are usually more like 10 kJ/US$. You get a multiplier of about 3 because diesel engines are typically about 35% efficient and electric motors are about 95% efficient, so you only need 70 kJ/tonne/km. But 500 km of range would still cost you 175 grand of lead-acid batteries for every 100-tonne railroad car in the train, which more than doubles the cost of the train. If you use lithium-ion instead, it's twice that: US$350k a car. So, expect this to take a significant amount of investment, and therefore take a couple of decades—if it happens at all, because quite possibly it's all-around cheaper to use cheap solar energy to produce ammonia or hydrocarbons and burn those on the train. The inability to detoxify waste is a concern because detoxifying is what we normally do with hazardous waste. Learning to handle hazardous waste in a different way is risky and will involve some accidents. I mean, it already has.
kragen 6y ago
> The comment said that solar powered trains would only be able to run at night if wind generation is sufficient to power them in the absence of solar power To be perfectly fair, while that's presumably what you meant—and it's a sensible point—what you said was, "making it so that trains only run at night and on windy days".
- sir_bearington 6y ago
  Yes, trains can only run at night when it's also windy. I'm not sure how you arrive at the conclusion that solar powered trains can only run at night, short of willful misinterpretation.
  - kragen 6y ago
    Well, if something runs only at night and on windy days, that means it runs at night, regardless of whether there is wind, and that it runs on windy days—which might mean "24-hour periods that have a lot of wind", thus also including the night, or "non-night periods that have a lot of wind", due to the semantic ambiguity of the English word "day". In this case, though, the ambiguity doesn't matter; it comes to the same thing. But the meaning is different from your intended meaning. A different way of stating the meaning of "only at night and on windy days" is "always, except in the daytime when it isn't windy". But of course the daytime when it isn't windy is precisely when it's actually possible to run solar-powered trains without batteries, at least if you run overhead powerlines or a third rail down the whole train track. What you meant was "trains run at night only on windy days", which could also be validly phrased (at the cost of some ambiguity) as "trains only run at night on windy days". But the extra "and" that you inserted in the middle of the phrase made it impossible to read the phrase as having your intended meaning. Perhaps you hadn't noticed the extra "and" when I quoted it in my earlier comment above, accounting for your confusion. Or perhaps you just don't speak English very well. Which is okay! I'm a second-language speaker too, and it's hard at times! But it's not a valid reason to accuse people of willfully misinterpreting you.
    - sir_bearington 6y ago

kragen 6y ago

Aha, thanks for clearing that up. I think probably trains will have an easier time carrying batteries than electric cars do: a one-tonne diesel internal-combustion-engine car might get (in medieval units) 40 miles per gallon of fuel, while diesel freight trains routinely get 480 miles per tonne-gallon. Teslas need to recharge about every 500 miles, so we should expect battery-powered electric freight trains with the same battery mass fraction as a Tesla to need to swap batteries roughly every 6000 miles or 10000 km. A night train making it through the night isn't going to be a problem. If that's true, then why haven't batteries already replaced diesel engines in diesel-electric locomotives? I suspect it's a matter of battery costs and network effects. A gallon of diesel is 146 MJ, so a tonne-mile on a freight train costs 300 kJ, or 189 kJ/tonne/km in non-medieval units. Lead-acid batteries only give you roughly 20 kJ/US$, and low-power lithium-ion batteries are usually more like 10 kJ/US$. You get a multiplier of about 3 because diesel engines are typically about 35% efficient and electric motors are about 95% efficient, so you only need 70 kJ/tonne/km. But 500 km of range would still cost you 175 grand of lead-acid batteries for every 100-tonne railroad car in the train, which more than doubles the cost of the train. If you use lithium-ion instead, it's twice that: US$350k a car. So, expect this to take a significant amount of investment, and therefore take a couple of decades—if it happens at all, because quite possibly it's all-around cheaper to use cheap solar energy to produce ammonia or hydrocarbons and burn those on the train. The inability to detoxify waste is a concern because detoxifying is what we normally do with hazardous waste. Learning to handle hazardous waste in a different way is risky and will involve some accidents. I mean, it already has.

kragen 6y ago

> The comment said that solar powered trains would only be able to run at night if wind generation is sufficient to power them in the absence of solar power To be perfectly fair, while that's presumably what you meant—and it's a sensible point—what you said was, "making it so that trains only run at night and on windy days".

sir_bearington 6y ago
Yes, trains can only run at night when it's also windy. I'm not sure how you arrive at the conclusion that solar powered trains can only run at night, short of willful misinterpretation.
- kragen 6y ago
  Well, if something runs only at night and on windy days, that means it runs at night, regardless of whether there is wind, and that it runs on windy days—which might mean "24-hour periods that have a lot of wind", thus also including the night, or "non-night periods that have a lot of wind", due to the semantic ambiguity of the English word "day". In this case, though, the ambiguity doesn't matter; it comes to the same thing. But the meaning is different from your intended meaning. A different way of stating the meaning of "only at night and on windy days" is "always, except in the daytime when it isn't windy". But of course the daytime when it isn't windy is precisely when it's actually possible to run solar-powered trains without batteries, at least if you run overhead powerlines or a third rail down the whole train track. What you meant was "trains run at night only on windy days", which could also be validly phrased (at the cost of some ambiguity) as "trains only run at night on windy days". But the extra "and" that you inserted in the middle of the phrase made it impossible to read the phrase as having your intended meaning. Perhaps you hadn't noticed the extra "and" when I quoted it in my earlier comment above, accounting for your confusion. Or perhaps you just don't speak English very well. Which is okay! I'm a second-language speaker too, and it's hard at times! But it's not a valid reason to accuse people of willfully misinterpreting you.
  - sir_bearington 6y ago