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Just a heads up, you don't need an electric panel upgrade anymore for charging. There are UL-certified systems that monitor the power use for the whole panel and load shed the EV charger if needed.

I installed one from Emporia, for about $500.


plus there devices where you can even share a dryer outlet dynamically (turns car charger off when dryer is running) - if your dryer outlet is near at garage.

> For SpaceX's 175 kW satellites

That's like a quarter of a rack of modern AI hardware. Modern AI datacenters are now in the multi-GW range.


Okay, so you agree the cooling problem has a solution.

Now the argument is, what, you can't launch that many satellites?


The argument is that launching and operating those satellites is more expensive than just using the same silicon on the ground.

How sure are you of that? How much does each satellite cost? How much will silicon on the ground cost in 2030?

How can anyone be certain of any of those numbers without (a) knowing how the technology will evolve, and (b) doing the math?

I'm just astounded that people can have such confidence.


We know such thing as physics and economics. That dictate the fundamental limits.

They are showing that space-based DCs only make sense for criminal enterprises. Which probably IS what's going on here.


I don't think that is the argument, or if so it's an odd one because it's just a fact right now. Instead, people are claiming that it will never be feasible from a purely physics standpoint, which is something debatable.

Saying it’s impossible isn’t debatable because it obviously is. What would stop you from a physics standpoint to just launch 100 ISS with Server racks in each? A few kW of installed power in space is already reality, it’s just really expensive.

It's a fundamental physics problem. You need to have huge radiating surfaces.

A 1GW datacenter with chips operating at 100C (which is probably doable) will need a radiator that has a surface of one square _kilometer_, and this is with all the favorable assumptions. Realistically you'll need about 2x of that.

If you want your DCs to be on a 1000km orbit (for reasonable ping times), you'll be able to _resolve_ these satellites with a naked eye!

Sorry. But this idea is fundamentally unworkable.


The current plan is for 250 kW peak with 160 m^2 radiators. It will weigh about 4 tons so you can pack 25 on one flight of Starship.

Deploy 4,000 and you're at 1 GW. That's 160 launches.

BTW: SpaceX has already manufactured and launched 10,000 Starlink satellites and Falcon 9 launches about 150 times per year. None of this seems unworkable.


Can we solve the fertilizer price problem by hauling it with airplanes? Yes, we can! It's easy, just load the potash fertilizer into an airplane and unload it directly into the traincars. I even designed a neat conveyor belt system to speed up unloading!

Look at the numbers. 1kW of nuclear power capacity on Earth is around $2000, and that's 24/7 guaranteed power. So a 250kW cluster needs $500000 to cover its power demand with near 100% reliability and with some ongoing cost.

And if we're OK with some interruptions, then we can use solar+wind at around $100000 and with essentially no ongoing cost. If we assume the absolutely best projected launch cost of $100 per kg (vs the current one of ~$800), that's just 1 ton of material in space!

So you're off by 2-3 orders of magnitude in cost. And this kind of "it's unprofitable" is actually a fundamental issue.


Okay, so you admit it is possible. Cooling is not the problem. We're making progress.

Now your argument is that it's unprofitable. Here's the calculator: https://andrewmccalip.com/space-datacenters

Specifically, if SpaceX can get the price of a satellite down to $8 per watt (about $2 million USD) then it will compete with terrestrial.

I just don't understand how you can be so certain that they can't do that. I'm not certain that they can, but being certain that it's impossible seems completely evidence-free.


This calcualtor is bullshit (inflated terrestrial costs and underflated orbital costs). It doesn't pass the basic sniff test: $15B for 1GW of terrestrial power is more than enough to build AN ENTIRE 3GWe NUCLEAR POWER PLANT. From scratch. With 75 years of expected life.

So no, the calculations show that space is NOT feasible unless you want to do that for nefarious reasons: evading regulations, using AI for criminal enterprises, military use, that sort of thing.

Only these applications have the profit margin that even comes close to justifying it.


Do we even _have_ semiconductors that can work at 220C? And if you're thinking about using some kind of refrigeration cycle, its efficiency is going to be bad.

1) The chips don't reach 220C. The 220C is the temperature at the hot end of the heat pump. The chips are on the cold end of the heat pump.

2) The International Space Station has used a dual-loop ammonia/water-based heat pump to cool the station temperatures. It's been in place for several decades. Heat pumps are a proven technology.

Other satellites have also used heat pumps, such as SES-17 in geostationary orbit https://www.esa.int/Applications/Connectivity_and_Secure_Com...


> The 220C is the temperature at the hot end of the heat pump. The chips are on the cold end of the heat pump.

If we want the heat pump's cold end at about 40–65°C, then for each 1MW of GPU heat, we need another 1MW of heat pump power. Now you need 2MW of solar power.

Good news is that the radiator at 227C (500K) can emit about 5× more heat per square meter than at 57C (330K)


ISS's two external cooling loops hold about 540 kg of ammonia combined, together they dump 70 kW.

Of course. But their hot ends are nowhere near 220C. I don't think such heat pumps even exist right now except in labs.

Looks like some experimental pumps within this region have CoP around 30%: https://www.sciencedirect.com/science/article/abs/pii/S03605...

So you'll need a lot of additional energy to run the pumps. Which will require additional radiator area.


Dear F-Droud, please stop redirecting me to the Mandarin version automatically without an option to read the original message. Just because I have a Chinese keyboard layout available.

What Accept-Language header are you sending?

Not sure, it happened on mobile Firefox. My point is that there should be a way to disable it and switch to a different language manually.

https://wutools.com/dev/testing-debugging/http-header-viewer

First hit for 'check http headers', in case that helps find out why websites think you want Chinese content. Maybe it's a bug in the website; maybe it's set as your first preference. Please report the bug if there is one!


And I'm actually stumped. Firefox is just sending `en-US` on mobile.

I have no idea why it selected Mandarin. I can switch back to English by using the "desktop site" feature that _does_ have a language dropdown.


That's strange, sounds worth reporting. They should be able to tell you if there's anything else to check (maybe some javascript interface says Chinese is the way to go) or if it's really just some strange bug on their end (misdetection of the ip address or so)

> would never have worked in userspace macOS or windows

It could have worked in macOS! It implements RFC-2367 (PF_KEY socket type) and I even made it work on my laptop.

I traced the SA database operations on Windows, and it could have been done. Probably. But I abandoned that to preserve my sanity.


IPSec suffers from the "it can do everything" syndrome.

Storytime: 15 years ago I co-founded a startup to build easy-to-use infrastructure management for AWS. At that time, it did not have cross-region VPC peering or routing, so you couldn't easily and safely have apps that communicate between regions.

So I started working on creating an overlay network. My idea was to use IPsec, it even has an RFC that documents its kernel interface. So that when a host wants to send a packet to the secure network, the kernel goes to my userspace daemon, that in turn goes to the central server that provides it the key for the given host pair.

And it turned out that the interface lacked a crucial part - on-demand key negotiation for incoming packets. It had this for _outgoing_ packets, but not incoming. The only sane way to make it work was to create a proactively updated database of all the hosts.

Well, I did that. It also did not work (tm). I found so many issues with broken MTU handling, broken NAT traversal, etc.

I eventually gave up on that idea and started working on a simple TUN/TAP-based overlay. I almost made everything work, but our startup got acquired by AWS, and this line of work was abandoned.


> France is still shutting down its plants because the rivers are too warm in the summer.

That's because French nuclear power plants are designed to be directly cooled by river water instead of using cooling towers.

The biggest nuclear power plant in the US (Palo Verde Generating Station in Arizona) is cooled by evaporating the treated wastewater, in the desert.


All these extra methods of preserving water adds cost, to a technology where paid off plants are struggling. Let alone ruinously expensive new builds.

At least these installations don't need to deal with radioactive material directly, so they will have the same financial infact as similar improvements to, say, coal-fired power plants.

They don't materially affect the cost of a nuclear power plant. Cooling towers or evaporating ponds are not expensive. Coal and gas power plants also use them.

You just can't easily retrofit them onto an _existing_ power plant.


If they were essentially free all plants would be built with them. Evidently they are not free.

> If they were essentially free all plants would be built with them.

Pretty much all the new thermal power plants are (including biomass-burning plants), except in places where cool water is not scarce.

It's weird to glomp onto that idea, as if it's some kind of a fatal flaw of nuclear power.


Large reactors require unobtanium-class material engineering. Only a few companies in the _world_ can make large reactor vessels.

In contrast, SMRs are being sold as something that you can weld together in your garage and use them as a replacement for your water heater. And you don't need all those large containment structures and gigawatt-scale turbines.

This makes it much easier to get funding, as you don't need to show that you have a firm agreement with all the suppliers.

I don't like this at all, but it _might_ result in us regaining some experience in building nuclear power plants.


It won't! That's the amazing thing about electricity.

While having 12kV going through panels is not safe for many reasons, having 300V at 10-20A is completely normal.

12kV is impractical because these voltages can jump quite far, and you need a lot of insulation for them to be safe.


And so ultimately, despite my details being wrong about currents, the notion of stringing miles of panels together is probably not a good basis for rejecting the panels over the canals.

In reality, you shouldn't string a lot of panels together for other reasons. An obstructed panel doesn't just not produce energy. It acts as a resistor, _wasting_ energy that flows through it.

You would have short strings of panels and small string inverters built every ~100 meters along the channel. Inverters will also connect to the high-voltage bus cable, likely buried in a trench along the channel. And most channels in California are not gravity-fed, so they already need pump stations along the way and have power distribution systems for them.


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