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About 1kW per household. The trouble is, that's just about enough for *average* demand, not winter demand.

Loops in Morecambe Bay might cut it.

But for space heating, I think ceiling radiators + air source heat pumps are the place to start. Having ceiling radiators makes switching to a heat grid later easier.

The centre of town is dense terraces, but with back alleys, and there are car parks we could sink boreholes into (car parks which absorb heat during the summer hmm...). Back alleys are already used for water mains; we could install the heating grid without too much road disturbance I think. Especially in the central triangle.

I care far more about my hometown than I do about Londoners. Afaic, I might as well work on one for Dublin lol. Or Berlin.

Also my town has obvious places to start and a somewhat functional town council. I suppose my university does also.

A London system would not be one system anyway. It's far too big for that.

As much as I love the the Boynton Monorail, I have to admit that this system is probably the easiest way to build out a public transit system, since it can switch to regular bus street running where right of way is difficult to acquire (and is simpler and cheaper than having an upper support rail). A metropolis such as Manchester, where there are plentiful open spaces but not necessarily contiguous ones, could construct dedicated sections where it is straightforward to do so and operate as buses in the built up patches. Then, over time, as space can be acquired, tracks can be laid down to complete the circuit.

If the rails are built to support the weight of a HGV, we could do the same with lorries, with the chassis having retractable steel wheels. Relieving the weight from the rubber tyres would cut down massively on the problems they cause in terms of road damage and pollution. We could build out a cross country network of such routes. Unlike using railways, there would be no time consuming step of transferring containers, though we could also of course connect them into trains to get significant labour and energy savings and separate them out at the end for last mile travel.

If we really wanted to go low embodied energy for solar... could the mirrors for a compact linear fresnel reflector be made out of wood and foil? The strength requirements should be a lot lower than for a parabolic trough, and the mirrors are either flat or slightly curved. AFAICT the mirror slats themselves are adjusted to account for changing solar angle.

In the area of sacrificing efficiency for cost, how do Fresnel lenses compare?

Trying to get figures for the round trip efficiency of ammonia energy storage -- Ammonia for energy storage: economic and technical analysis

The figures given range from 34% (Haber-Bosch, gas turbine) to 72% (reversible fuel cell). Predicted cost for the latter is $0.24/kWh, so pretty pricey. As previously talked about, ammonia can be shipped around the world, so it can be synthesised where there is cheap power available, such as deserts with solar thermal electricity generation.

I don't see ammonia being used in road vehicles, given its toxicity, but as a fuel for ships or electricity generation where we're not expecting Average Joe to handle it it could be a contender. Pricey, even with a cheap source of electricity for producing it, but the storability makes it one of the few options to keep the grid on for the dozen or so windless weeks we have each year in Britain. Probably we'll want to have a dual/triple tariff system where the priciness is made clear to consumers, rather than trying to average it out over the year...

What I'm seeing from discussions of solar thermal power and synfuel is, whilst getting cheap energy is difficult, we can probably get cheap enough energy to keep our technological civilisation going at least if we make a few adjustments. You won't get to drive a gaz guzzeleen muscle car, but keeping an efficient (hybrid?) compact on the road will be a possibility. Electricity will be pricey but we can make up for it in part by going big on cheap hot water. Maybe we have to cut back on energy intensive materials, but we'll still have a shipping industry. The core parts will keep going.

It's pretty clear that EROI for solar panels very strongly depends on where they're placed. It would not surprise me if the studies claiming the highest EROI are based on desert installations with high efficiency panels.

Which... sure, if you're looking to make synthetic fuel or ammonia, that's not necessarily a problem. If you're looking to produce electricity for non desert regions however, you find yourself needing very large scale investment in politically risky high voltage power lines...

No, not really. All you have to do is assume a capacity factor of 25%. Which for solar would be a really good capacity factor; in Britain it's more like 10% (but we're not exactly the sort of place you'd put solar if you were thinking straight).

kbd,

Why are you like this. You always answer innocuous questions in a really aggressive manner as if you've been personally offended. Go reread my post and highlight where I talked about lockdowns being brilliant and how it was great people lost their jobs.

Hmm. I wonder how the steel requirements compare for Vertical Axis Wind Turbines?

Contra-rotating floating turbines promise unprecedented scale and power

There's been a trend in wind power to go for larger and large individual turbines, but that's not necessarily the way to optimise for costs. VAWTs can be clustered together in ways HAWTs can't be, and not being top heavy their foundations should require far less engineering work. If they have foundations at all.

They might take up more space, but *gestures at the north sea*

I don't see a future for large amounts of grid battery storage. If we build in two days worth of compressed air, why would we not use that to buffer hourly fluctuations too? Why spend money on a more expensive system thats redundant? So the place for batteries is frequency control, which means they're competing against flywheels on response speed and cost. Maybe they can beat them there, but flywheels are pretty quick and can last a very high number of cycles without needing to be rebuilt.

The place for batteries is mobile equipment. They can't win against hydrogen when it comes to aircraft, they're nowhere near  energy dense enough. Trains are straightforward to electrify, we've done this for like a century and a half now, though maybe they have a niche role on branch lines. Heavy equipment... well, they're certainly good at the heavy part. Maybe they can play a role there, or maybe the advantages of ammonia or hydrogen will be too great for them to succeed. Shipping, I can definitely see an ammonia powered shipping future, the shipping industry is no stranger to hazards so I can't imagine they'll be put off by the need to be careful around the fuel if it turns out to be the cheapest replacement for oil.

Which leaves cars. The one place batteries could stand a chance, and the least necessary by far of all the areas I mentioned. So I'm not really that worried about whether or not we can have enough lithium; driving is not some god we must devote our civilisation to. We got by before the Ford era and we'll get by after it.

The more worrisome part of running out of cheap fuels is stuff like cement and metal production. Those will get more expensive I'm sure. At the same time, we're also pretty  profligate in using them. We can live without steel and glass towers too.

Talking about the material consumption... leaving aside the energy use, how does the labour use compare? "100,000 green jobs" is not something to be proud of, each of those jobs represents an energy price increase. How many people need to be employed in rebuilding the energy infrastructure every decade or so?

As far as spinning reserve for grids is concerned, I'm not too worried. Flywheels don't require any scarce materials, at least not in large quantities. The british national grid has a few projects in the pipeline to use them for grid stabilisation (of course, ideally they'd be colocated with the intermittent sources so the frequency response comes where the power enters the system...). Expensive, but we only need a few minutes of storage before other cheaper sources can come online, and flywheels last for a looong time. Between those projects and the liquid/compressed air schemes, I think we'll have a grid that at least fails gracefully. Rolling blackouts with a few hours warning instead of crashing...

Regarding longer duration storage, one thing that is glossed over in discussions is how frequently they will be cycled. Flywheels could easily be cycled thousands of times a year, because they buffer very short term fluctuations; the sort of 50hr storage we'll need to run the grid on wind might be cycled only a hundred times a year at best. So it needs to be very cheap in order to pay for itself over a reasonable timescale. AFAIK only underwater CAES approaches that sort of cost; hydrogen is still about twice as expensive, and suffers terribly from low roundtrip efficiency (though this was before the Hysata electrolyser was unveiled). Energy Storage Cost and Performance Database -- Pacific Northwest National Laboratory. People will try to argue batteries are still somehow better, but they're arguing with the Department of Energy when they do so, not just with me.