> You have a high pressure helium tank, closed, but connected to a large empty balloon, underwater. You open the tank and fill the balloon with a significant volume (should work if enough pressure in the tank). Will the system start floating?

If the balloon is big enough, yes.

Exactly the same thing will happen as if you do it in normal air. Imagine hooking up a very high pressure helium tank to a blimp, and inflating the blimp, so that it takes off with the tank attached.

https://en.m.wikipedia.org/wiki/Concentrated_solar_power

It seems they want to use steam for some reason.

I would imagine CSP plants to be operating as ORC Organic rankine cycle) plants as they can achieve evaporation in lower temperatures and dont need water in their circulation.

CSP plants also have added benefit that can be used in some sort of heat storage solutions which would enable production in cloudy/ night times. I remember reading that the material heated in focal towers is some salt that actually melts there.

Lithium-6 weights about double of tritium (Hydrogen-3). So for 1 kg tritium you need 2 kg lithium.

Why would you need twice as much if one lithium atom produces one tritium atom?

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All thermal power plants (solar and fossil fuel) have significant inefficiency related to the difficulty of converting heat into work. So the turbine contributes to the inefficiency but isn't the biggest factor. Solar thermal power generation looks less good considering this.

For things where you really need heat, like cooking or heating water, you can avoid that inefficiency of converting light or heat to power; for example, lots of people heat their hot water by collecting heat directly from collectors on their roof. However, despite the increased efficiency, this isn't necessarily cost-effective compared to other means of reducing fossil fuel energy use--electricity is just a really practical way to move energy around.

A lot of residential buildings have resistive heating. Baseboard radiators, cable ceiling, regular forced air heating are all potentially resistive heating.

Regarding how close residential heat pumps can get to 3x the efficiency of resistive heating- that's about where they are right now. Depending on the temperature at the exchanger, a bit better than 3x is not uncommon. But they become less efficient outside of optimal working temps.

There is an otherwise kind of bland sci-fi series written by Jack Campbell where the first alien species humans encounter is aquatic, so they take advantage of their water filled ships to pull off more g’s than vessels filled with humans and air could safely attempt.

There are tiny hairs that "measure" the flow of the of the liquid and once you have been spinning the measurements are no longer accurate so the data from the hairs is corrupted so you haven't a lue which way is up.

Our atmosphere is mostly nitrogen already, so you probably wouldn't notice any difference. Since there would be a higher gas pressure of nitrogen in the air than in the blood, the lungs would absorb inhaled nitrogen, then because there would be a lower gas pressure of oxygen & CO2 in the air than in the blood the lungs would expel those gasses. The exchanging oxygen out part would happen in any oxygen-deficient atmosphere, like e.g. an argon purge or very thin air, like if an airplane's cabin depressurizes.

If you walked into a vessel under nitrogen purge could you physically take a breath of nitrogen in and out ? Or will your body just not respond. In the few seconds you'd have before you pass out of course

It could within some range. It would be best as a heat pump for heating from moderately warm temperatures up to high temperatures, perhaps 40° C up to 100° C, for example.

Note that that's also how a conventional heat pump works, with an HFC refrigerant. Let's say it's operating between 10° C and 40° C. The evaporator pressure will be set up so that the boiling point of the HFC is around 10° C, and the condenser pressure will be high enough to make the boiling point there 40° C.

>However without the breathing apparatus and no suitable oxygen to breath then your body will not be triggered to expel carbon dioxide and you will just not be able to breath at all which will lead to death.

Lungs work as simple gas exchangers; nothing "triggers" them to absorb oxygen or expel CO2. Atmospheric air has a higher concentration of oxygen than the blood in the lungs, thus oxygen will permeate through the membrane due the higher specific gas pressure on one side. Same thing but in reverse for CO2.

What you might have been thinking about is the mechanism that causes the body to feel the need to breathe, which is triggered by high blood CO2 rather than low blood oxygen. Since as long as there is a lower concentration of CO2 in the air compared to the blood CO2 will permeate across the membrane & leave the body, this mechanism won't see anything being wrong even in an oxygen-deficient atmosphere. This is why, for example, a vessel under nitrogen purge is so dangerous; if a worker enters one they won't feel like anything is wrong until they drop unconcious in about 30 seconds.

One big disadvantage of solar thermal is that it doesn't work when it's cloudy. Conventional (photovoltaic) solar panels work fine with the diffuse light from an overcast sky, but you cannot focus diffuse light to create high temperature.

It's also mechanically complicated. Not only do you need a turbine (or Stirling engine) but you also need a tracking device to adjust the mirror angle continuously. Whereas conventional solar panels have no moving parts at all.

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There would be a danger of a localized kaboom, once the plasma loses containment it disperses - explosively. But I'm going to assume the amount of fuel in the reactor is going to be minimal, after all you're after a controlled fusion reaction. Once the fuel is spent or the pressure/temperature is too low to sustain fusion, the reaction ends.

This right here is why I don't know of any start ups making large tokamaks, and are instead doing something like liquid cooling with liquid zinc or direct capture with magnets.

It doesn’t scale down well. 1 solar panel can generate power, but for the CSP it needs a very large central heat engine and lots of mirrors surrounding it to focus light at the center.

It’s also very water intensive, which is seen as a waste because it needs to be put in places with a lot of sun, which tend to be dry and water scarce.

Why isn't it more hyped and spread?

That’s called concentrated solar power, and it uses a lot of mirrors to focus the sun’s heat onto a bunch of salt to melt it down and use it to generate electricity.

Apparently its efficiency is similar to that of solar panels. But it should be cheaper since you don’t need expensive materials for all the solar panels, only normal mirrors.

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I would also add that Earth-Moon-Earth propagation can also cause Doppler shift to a meaningful degree.