OK Fester,
Well the 15% figure seems very low because it means that you
need over 6 times the number of turbines spread all over the country
to get 100%. Of course the odds are that there would be times when
they would get more than 100% but that means they would also get less
than 100% other times.
This explains figures I have seen that, provided your country is big
enough, you need 12 times the nameplate rating turbines.

Theoretically solar with tracking would mean about 40% times the ratio
of cloudy days. Likewise some days more, some less. Near the Tropic
of Capricorn would be best I think. I guess 40% judging by my solar
cells in midwinter.

These would be reasons why renewables are so much more expensive than coal.

I remember reading something about that a long time ago. One of the
major co2 generation in their building was cement. There was however
many other items of course but they are a once off in the construction.
There was also a controversy about whether you count everything.
The CO2 in making the maintenance mans van, his fuel, the house his
family lives in, his wife's travel, the kids school, the access roads,
the list of everything that is needed to build and maintain the wind farm.
No one has to really worry about all that as it will all come out at
the bottom line and it will live or die on the cost.

Fester,
An ammonia plant using the hater process is always inefficient! Considering the enormous energy consumption and CO2 emissions of ammonia plants around the world, it's well worth spending spending large amounts of public money on R&D to make the efficient alternatives cheaper and more reliable.

Whether it's worth building a plant that won't operate 24seven depends not only on the cost of electricity, but also on the cost of capital – the lower interest rates are, the more likely such an investment is to be profitable. Currently they're at record lows, and could fall further.

Batterries make the job easier - with batteries doing the short term load balancing, the plant can stay on or off for days at a time, so there'd be no need for staff to hang around idle.

Re countries with cheaper power entirely from renewables, Iceland is the obvious example. It's probably one you'll reject because it's not from solar and wind – but those have only recently become cheaper than coal, so of course no country is in that position yet. I suggest you have a look at Sanjeev Gupta's plans for Whyalla – he's taking advantage of cheap solar power; not from the grid, but directly from solar panels directly to the steelworks, and also TO the grid.

I'll probably deal with most of your claims on the other thread tonight, but meanwhile see my response to Bazz:

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Bazz,
There you go again with the outdated claim that coal is cheaper than renewables even though in this thread I've linked to a CSIRO report that says otherwise. Clearly you and Fester haven't read the report – otherwise you'd know that the comparison is based on meeting our objectives, not nameplate capacity.

Yes, cement production's a huge producer of CO2, though considerable efforts are being made to try and reduce this. One important discovery was that they could save a lot of energy by grinding the clinker while it's still hot.

You can safely disregard any report disingenuous enough to include the kids school in the environmental costs of a wind farm!

Aidan,

The research I read on ammonia would suggest more interest in modifying the Haber process to work at lower pressure and temperature by using catalysts and by continuously harvesting ammonia from the reaction. An efficiency of >86% would be required for the modified process to be economically competitive with the current process. In contrast, the rubbish that BS is pursuing has slightly higher efficiency than the commercial Haber process(roughly 70% vs 66%), but operates at a few percent of the rate, perhaps closer to one percent. I would guess that it also has a very long list of other cost, reliability and scaling problems to overcome.

The idea of having an ammonia plant is to make money from its output. I doubt you would find many willing to leave such an asset idle for 75% of the time.

Aidan please answer the question: How are we going to feed a high rise city? What fuels trucks, long distance freight trains, planes and ships?

Fester,
I'm sure Shorten wouldn't be averse to anyone modifying the Haber process to make it more efficient. But AIUI the alternative process he favours has scope for further efficiency gain. And your comparison of the rate is meaningless as you don't say what you're comparing it by. The more production infrastructure you have, the more you produce. So when you say "a few percent of the rate, perhaps closer to one percent", what are you assuming to be equal?

And yes, of course there's a lot of other problems to overcome - hence the importance of public investment.

How much of the time an asset can profitably be idle for depends, as I said, on the cost of capital and the cost of other inputs. AIUI in ammonia production the energy costs are overwhelmingly dominant. Have I misunderstood that?

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Josephus,
Why do you bother addressing such stupid questions to me? Surely you know that we'd use farms to feed a high rise city, and that planes use kerosene and most other long distance transport uses diesel?

I could add that it's possible some high value crops will be grown within the city – see https://www.abc.net.au/news/2018-06-10/farms-of-the-future:-growing-crops-without-the-sun/9855578

I could also add that not only are there alternatives to diesel, but also alternative ways to make it - it doesn't have to rely on fossil sources. But until I know why you're asking the question, and why you're asking me, I'm not going to bother going into more detail.