Zakharra wrote: Any engine, even a steam engine or a stirling, would be polluting if it burns fuel for heat, so you'd still have pollution by driving no matter what.
Otto cycle in practice is 20% efficient. Discontinuous combustion is inherently incomplete and gives pollution problems. More efficient (~35% for Stirling, steam isn't one number) means less fuel burned; continuous means less pollution. Stanley Steamers really did produce nearly no tailpipe emissions. If the same billions of dollars of investment had gone into that technology we'd have a much smaller problem today.
Zakharra wrote:Fossil fuels such as oil burn faster and produce a lot more energy for each unit burned than anything out there. It's one reason we still burn it and why ethanol fuel is bad. Ethanol or alcohol based fuels simply aren't near as effective or efficient. What are the ling term effects of fossil fuels on agriculture? I was under the impression that overfarming and such would do in the soil, not burning gasoline/diesel.
Fossil fuels are a very obvious short-term benefit. Long term, we get melting ice caps and unpredictable weather. Farming is enough like work without unpredictable weather. (Consider 2012, only worse, and five in a row. That would be very bad, and that seems to be where we're headed.)
We also get toxicity due to fossil-carbon-derived fertilizers (too much phosphate is a related but distinct problem) but mostly we're totally dependent on machine agriculture; 1% of the population grows the food, if you go back and look at animal traction with machines it's around 50%. (This is an interesting transition to go through, presumably also for Safehold; even Old Charis still has a lot of large landlords, which will make it more interesting.)
Bio-anything as a source of liquid fuel is just monumentally inefficient solar; you can't get even 1% conversion efficiency of sunlight into plant with terrestrial plants, and then you can't ferment the whole plant. People are trying, and they might get there, by genetically engineering micro-organisms to more completely convert the crop; you're still starting at that 1%, that's your absolute efficiency ceiling. Even if you can produce algae at 5% solar conversion efficiency it looks really bad next to solar cells.
Zakharra wrote: Cities? So you want everyone packed into highrises because that is an efficient use of space? That doesn't seem very healthy for anyone, mentally or physically, to be forced to live like that. I know I'd hate living in a city. I like having lots of space around. For such a population dense area, you'd need a LOT of mass transit to move millions and millions of people around. That means more trains, buses and taxis (assuming you'd allow buses and taxis). That's a lot of fuel being burned anyways just moving people. It would also limit what you could carry so stocking up on groceries would be harder since you wouldn't be able to buy in bulk without a personal vehicle.
You do realize that more than half of everybody lives in cites, and the trend is increasing toward the city side? They can't be completely awful!
The cost and (importantly!) land area per person is less for pretty much any form of ground transport except cars. Do the thought experiment -- 50 people is 40 cars, or fifty bicycles, or one bus, or a third to a half of a subway car. How much road area does each require?
Once the city gets past a certain size, you can't use cars because there isn't room for enough lanes of traffic. 2000 cars per lane per hour is doing really well. One subway line turns out to be able to move 50,000 people an hour pretty straightforwardly. That's ~20 lanes of traffic if nothing goes wrong. If you want the economic benefits of a dense city -- and they're large! -- you need something other than cars.
Highrises are fine if the folks building them aren't constructing a collection of closets to maximize their condo sales, but what I actually want would be most easily described as the housing equivalent of credit unions. What gets built tends to serve the needs of capital rather than the residents; the fix for that is to make it easier to pool capital co-operatively for the purpose. Shared walls, more floors, and generally compact housing allows things like shared heating/cooling (suddenly the 12 residence unit can afford that big buried water tank heat sink for the heat pump! the soundproofing
is, etc.) and leaves more land available for parks and pleasances.
Oh, and if you live in a city, you can get your bulk groceries delivered. It's cheaper than keeping a car by plenty some lots.
Zakharra wrote:The wars happen anyways. People find reasons to kill each other no matter what.
[snip]
Nukes are a
really good reason to learn how to not set out to kill one another in job lots.
Zakharra wrote:It was clear in the 1970s that we should have been developing better and cleaner running more efficient engines. Until there is somehing that can equal the effectiveness of oil/gasoline/diesel engines nothing is going to replace it
Which is one of the reasons I like ammonia as a way to store protons; easy to synthesize, store, and it's pumpable. And the conversion tech both ways exists.
There are at least three other potential energy storage mechanisms -- abiotic, non-fossil methane, aluminium, and nano-electrode batteries of some chemistry or other (though I really hope not titanium/chlorine!) -- able to displace fossil carbon.
It'll take a certain amount of collective political will, though.
(And hopefully these are also good answers.