Lowest tech to generate electricity with mirror solar thermal tower

Question

I'm thinking of a story where one country gets very technologically advanced compared to its neighbours, and I figured the best way to do that is with one of those towers that create steam by mirroring a lot of sunlight into one point, then using that steam for energy (ideally electricity).

What is the earliest this story could somewhat plausibly start? (keeping history before it the same as in our timeline)

Some conditions:

• Obey laws of nature (no magic).
• Produce significant amounts of energy for the time (I imagine 10.000's horsepower), ideally as electricity.
• All parts must exist in the time period (or something technologically close).
• Only having energy when it's sunny is acceptable (though a workaround would be a nice bonus).
• Can be built in the most ideal place on Earth.
• I'm mostly interested in technology, so lets disregard social things like 'those technologies existed but in different countries' or 'a king would not be interested in funding this'.

Here's what I got:

• Electricity: 1600 William Gilbert? 1752 Ben Franklin?
• Steam engine: the idea may have been clear enough in 1606 Jerónimo de Ayanz y Beaumont? though in our reality it only really took off in 1698 with Thomas Savery
• Convex mirrors: glass-blowing in 14th century?
• Controlling mirrors: I know there were some pretty advanced ancient clockworks, though worst-case it can be done by hand

Answer 1

There are three gateway technology points here:

First, you need to be able to make reasonably high reflection mirrors (flat, if used in groups for a large area, or concave if single) to focus the light. This was possible in the Bronze Age.

Second, you need a way to turn heat into work. Newcomen had a steam powered water pump in the mid-17th century, which James Watt, as a lazy apprentice, automated (at least the valves) and then harnessed to produce mechanical work. It's long been claimed, without much supporting evidence, that Heron of Alexandria used steam and hot air to do work a millennium and a half earlier; it surely doesn't require anything beyond bronze age technology. It's known he was aware that steam could produce forces; it's not been proven (as far as I know) that he ever used it for anything other than demonstration.

Third, you need a way to turn mechanical work into electrical current. Faraday is the inventor of this technology -- it requires the understanding of conduction and, at least qualitatively, the interaction between magnetism and electricity. Magnets were known to the ancients, at least a lodestone; conduction was a 17th century discovery relative to static electricity, so it was waiting when Faraday came along in the 18th century and put the two together. The ancients could draw copper wire, so they lacked only the knowledge to be able to build a dynamo or alternator.

If you have the knowledge, then, Heron of Alexander had the skills to build the device -- as did many of the better smiths and artificers of his time. The knowledge, however, didn't all get put together until the 18th century.

In other words, bottom line: if they'd known what was needed, this technology could have been built well before the beginning of the Common Era. They had mirrors, they could make copper wire and tubing as well as bronze boilers, cylinders, and valves; they had access to natural magnets -- all during the Bronze Age, which collapsed in the 11th century BCE.

Answer 2

Electricity has it own league rules.

You can invent a steam motor by just observing you kettle boiling the water for a cup of tea. But you never will build an usable electric motor by just handle a pair of magnets in your hand.

https://en.wikipedia.org/wiki/James_Clerk_Maxwell

His most notable achievement was to formulate the classical theory of electromagnetic radiation, bringing together for the first time electricity, magnetism, and light as different manifestations of the same phenomenon. Maxwell's equations for electromagnetism have been called the "second great unification in physics"[3] where the first one had been realised by Isaac Newton.

Also famous is his contribution to Einstein future theories:

Einstein described Maxwell's work as the "most profound and the most fruitful that physics has experienced since the time of Newton".[8] Einstein, when he visited the University of Cambridge in 1922, was told by his host that he had done great things because he stood on Newton's shoulders; Einstein replied: "No I don't. I stand on the shoulders of Maxwell."

So, using electricity productively requires at least a high quality bulk of knowledge only available by the end of the 19 century.

Without Scientific method you don't even can start of dream of a solid ground to work.

https://en.wikipedia.org/wiki/Scientific_method

The scientific method is an empirical method of acquiring knowledge that has characterized the development of science since at least the 17th century.

Ancient Egyptians build the pyramids and other great things because they had all the necessary tools and knowledge available. You can make primitive precise engineering tools using wood and cotton string. But you can not build a electric meter using the same material.

All ancient magnets available by the time before scientists find out how to artificially magnetize iron were weak, not strong enough to be used in electric motors. And they could be not melted to be poured in a mold. Heated magnets lost their magnetism.

As people answered before me, you can build solar thermal tower with bronze age technology, but 10.000 HPs is impractical.

But all is not lost. You can create electricity mechanically. In deed lots of it!

https://en.wikipedia.org/wiki/Van_de_Graaff_generator

Associate the generator plus these batteries and you have some kind of electric machine:

https://en.wikipedia.org/wiki/Baghdad_Battery

Is it possible to create and store 1.2 gigawatts electrical charge into thousands of these batteries and create a time machine using a van_de_Graaff_generator?

I don't know.

I think it is possible to create a "death ray" with it!

https://en.wikipedia.org/wiki/Uzzah

https://gizmodo.com/the-engineer-who-said-the-ark-of-the-covenant-was-a-gia-1598583115

If Uzzah's history is true, yes the ark was a gigantic capacitor. Even by theological point of view Uzzah's death was an accident. What good all powerful being kill a good man making his job? The incident left king David upset!

Answer 3

After thinking about for some time

It is hard to tell really. If you remove motivation, funds out of list of actual problems and leave human resources and knowledge then it hard to tell.

Reason why it is hard to tell is mainly the knowledge of that time. Until last century humans really didn't had the proper knowledge for all that - thus they didn't and could not.

It means, you have to inject some additional knowledge to make things happen, and there begins the question of how much of it. Even with the answer - a reasonable amount, so that we can, in a year or two, teach almost illiterate workers to do their part in manufacturing chain of processes, it still does not help that much to determine lowest possible year.

As an example - electricity isn't such a hard thing to make, understanding how it works, principles and all that it has very litle to do with production of finished machine.

Hydrodynamic bearings, sufficiently high precision parts of round or flat shape it not that hard. For flat ones, you remember sequence and practice it few days and bum - mastery of production of A grade flats. Basic theory of that - okay a week of demonstration on exagregated clay and wood samples will build some workable virtual models in brains of worker-master.

Static electricity isn't that hard, but can be useful. Tesla coil to convert static electricity to low voltage, also isn't that hard to make it even at bronse age.

So they may not necessarly get the ability to develop and improve technologies, but it does not mean they can't make parts and assembly them.

The problem is very similar, if not identical, to bootstraping problem, there is some difference, but it also about simple actions to get something from nothing and use it to help yourself to build few more of next steps at least.

Bronse-copper mirror can be good enough and it can be used to focus ligth out of flat sheet just by pulling flat sheet by the middle. (GREENPOWERSCIENCE youtube channel did some similar experiment, to test Archimedes story, but can't find the video atm, and Archimedes is 200 years before Roman empire)

So that time(200BC-200AD) can be a good candidate - they had humans, they had the system of organising people, they had quite sofisticated knowledge(people with that knowledge to teach workers), they had access to ores, stones, land resources etc. After RE fell, there is a gap of low quality time - but still does not mean impossible, just depends. I do believe that RE had a chance, but they were totaly clueless that they had it - maybe there would be one country and hyperdrive space ships today if someone pushed them in rigth direction - knowledge and skills of that time in rigth place.

Egypt also had some chances, they had less knowledge, but they had the way to organise people in production chains, results of that still tourist attraction, I mean, it still stands.

NB

A lot of things can be done by hands. And I do not mean Artisan stuff.

That's quite importand moment, hands are a tool, very sensitive one, and we had it from very beginning. One can cut a part on metal lathe, producing a lot of metal chips, but after that for some very preciese stuff finish can done by hands with or without power tools(not for every 6D CNC cut part, but for special and useful cases and for some others as well). And after that it at precision limit, more than that makes little sense (due termal expansion and all that) except some science stuff.

Pipets which can be used to suck in and hold a single cell, (cool eh?) can be made out of glass pipe with quite simple procedure - local heating and pulling, cooling, pulling, heating. It also precursor for high vacuum pump. Glass isn't that hard if one knows how.

So from very old age people were capable, but they didn't know what and why. Best old old time is animal domestication period, which probably far beyond the scope of your timeline, but just saying.

On other hand it needs to mention that things we may think like pretty mundane or ordinary can be quite challenging and require a lot of reading experementations if one does not know how exactly. Because indirectly there a plenty of science backed in - as an example of such items I can name a crucible (for iron melting).

So simplicity can be very deceiving.

Roman empire, anything during and after Renaissance can be a good time.

But again, what use the energy has, because by itself it does not give advantage. Making growing crops be more efficient, and introduce some simple but scientific selection process for plants, and pest control, and irrigation - can be a more potent change, just because you have more people who are free to do other things, even if it is no more different than it is typical for the time.

I would say since 200BC people were capable to do your sun tower.

For reasons I mention earlier.

However, electricity as means to transfer energy is not necessarly the best, until things progress a lot.

In usa pneumatic hand tools are(were) quite popular, and such stuff indeed has certain advantages - simplicity of construction, weigth, distribution of air(pipes) is almost as flexible as electricity. (Production of flexible hoses will be a problem, so it more for stationary equipment, instead of electricity, but the same principle as with hand tools)

Hydraulics, just water, also quite potent solution for main line - your 10 MW source (which is just insane amount if power by that times)

As storage - some elevated pond, 50-100 meters up, can be decent accomulator, and that is about 10 cubis meter of water per second, few 10 inch pipes will do. Main pipelines not neccessarly have to be metal, basalt and diabase can be cast as well, and it is on pair with cast iron.

And water flow(trough pipe) can be converted in all sorts of energies.

For bearings - use hydrodynamic or static bearings, made with high precision out of stone - no special materials required.

So time really depends on your capacity to build tech chain for what you point as advantage. Selection of what will be advantage also depends on you.

If no new knowledge, except the concept, and probably simlpiest steam engine aka tesla turbine and bearings for it - then it is time when you have decent pipes and mirrors. Early 1800 may do probably - but the thing will have hard time to compete with that time burning for energy ways.

So you propabple have to choose before steam engine time. Basically making that named steam engine, it being the key piece of tech. Which not so much different from refferencing how things were rolling after that, and without electricity part it can naturally happen since 1300AD

So really there are no easy ways to point at some time. And only your handwaving will keep the tower from being replaced by a typical boiler at some less speciefic and more convinient place.

P.S.

Similarity with bootstraping drove me for most of the answer in direction to "make it happen", rather "sufficient chances of such thing happen naturally", but your time options do not seem to be consistent whith that as well, so maybe it is okay.

Answer 4

Mirrors are surprisingly high tech. Up until rather recently (historically speaking), the best mirrors were flattened and polished sheets of metal or pools of liquid (water, mercury). Constructing a concentrated-light solar power plant would require an enormous amount of reflectors and this would represent a huge investment in metal, polishing time, etc. Additionally, hammering out a sheet of metal so that it's flat enough to be reasonably focus-able on a distant target isn't easy.

The simplest and earliest way to generate power would probably be by using hydropower. Water wheels are old tech, and with a skilled carpenter, constructable entirely out of wood in a sustainable manner. They can also provide an enormous amount of power, provided that the water is managed properly with something like a dam. You'd probably end up using multiple water wheels, and by connecting them up to electrical generators (you can construct an AC generator without magnets), you can generate quite a bit of power.

To increase power generation, you'll probably want to get your metallurgists to build a turbine though, because traditional spoke-and-paddle water wheels are quite inefficient.

This use of hydropower gives you a lot of flexibility on when to have your story take place (they've existed since 4000 BCE) and wire-making is a rather old technology too.

Here's how you could play out this development:

• Pick a nation or a specific city that is located on a river or in an area with a lot of rivers and that uses a lot of water wheels to power their mills.

• In an attempt to strengthen a water wheel's systems, a metalworker is hired to include some metal in the construction. Unfortunately though, it turns out to be very difficult to fit and attach a proper part, so instead, the metalworker decides to simply wrap several parts of the mechanism in wire.

• The water wheel works well, and over time, local workers start noticing something strange going on: pieces of metal will occasionally stick to the mechanisms (they've become magnetized) and if you touch it in the wrong place, you're liable to get a shock.

• Thinking the whole thing is cursed, the mill workers invite an expert to take a look and determine what's going on. Fortunately for history, this expert is brilliant or lucky enough to discover electricity based off of this.