I think you have to look at the actual orders of magnitude difference in raising the temperature of water versus air. The Arizona story you linked is about a study that found up to +4°F (+2.2°C) temperatures in air.

The same amount of heat, spread across the same volume of water moving at the same speeds, would only raise that water by 1/830 as much, for a +0.0048°F (+0.0027°C) 1/3300 as much, for a +0.0012°F/+0.00067°C temperature change across the same area/volume.

(I got to 830 by taking the specific heat of dry air of approx 1 J/g K at room temperature and regular atmospheric pressure and 1.22 kg/m^3, versus water’s 4.184 J/g K and 1000 kg/m^3).

(Edit: I fucked my math. Water has approximately 3300 times the heat capacity as air, per unit volume, and I just looked it up directly).

The higher conductivity of water might be offset by the higher convection potential of air (because air responds to temperature changes with differences in density/pressure, which creates wind in itself), so that the heat will spread through either medium relatively quickly and therefore dissipate very quickly with distance to the source.

I just don’t see a world where a data center raises the water by even 1°C, even locally.

The plants on the lakes so monitor the water temp so they don’t affect the ecosystem during the warmer seasons still.

Yeah, but look at the magnitudes of the heat units involved. Modern nuclear plants generate 0.6-4.5 GW at around 30% thermal efficiency (so they generate between 2-15GW of heat). These underwater data centers are looking at 25 MW (0.025 GW) while surrounded by water in 5 of the 6 3-dimensional directions.

There is some risk to local ecosystems, but we’re literally talking 2 or more orders of magnitude difference compared to nuclear plants or other thermal plants.

But that’s true no matter where you put the data center. If you have to dump the waste heat somewhere, the high density and specific heat of water is a better heatsink than the air around us.

This page says the ocean is about 352,670,000,000,000,000,000 gallons, which is about 1.3 x 10^21 liters, and each liter is a kg of water (yeah, yeah, the dissolved salt adds some mass but I don’t think it adds sufficient thermal mass to make a difference). It takes 4.184 kilojoules to raise 1kg of liquid water 1°C, and 1 joule is 2.778 x 10^-4 wh.

So that’s 1.55 x 10^18 watt hours, or 1,550,000 TWh.

Global electricity consumption is about 30,000 TWh per year, so if you use the entire world’s electricity consumption for 51 years you’d raise the oceans’ temperature by 1°C.

Or if you take global data center power capacity of about 125 GW, and ran them at full power 24/7, you’d be producing about 10.8 TWh per day or 3944 TWh per year. It’d take about 393 years of the world’s data centers to raise the ocean by 1°C.

Just goes to show that much more of the energy heating up our world and our oceans is coming from the sun heating up the planet and the planet failing to radiate it out past our greenhouse blanket, not from the actual heating of our atmosphere from our own energy sources.

GFCI doesn’t protect against arcs, so AFCI would be necessary to protect against arcing causing fires.

The danger with outdoor outlets is short circuiting (like when water drips onto a live wire), so GFCI is almost always required of outdoor outlets. Generally, outdoor outlets also require covers that keep the receptacle dry, at least when not in use (and more modern code generally requires it have an “in-use” cover that can stay on even when something is plugged in).

But having GFCI isn’t the same as AFCI, so arc fires can still theoretically happen.

For the hallway picture, each blue line corresponds with what should be a parallel line, along edges of square tiles or the corner of the floor and the two walls.

For the dinosaur doll, each white dot connects a feature on the dinosaur to that feature’s reflection.

For the shadows, each white dot connects a corner of the object to the corner of the shadow.

I think each of these lines is meticulously chosen.

Let’s also assume the heat capacity of the hot dog is about 3000 J/kg*K

So the specific heat of water at those temperatures is 4184 J/kg K, and those food court hot dogs are probably about the same as Kirkland dinner franks, which have about 73g of water, 31 g of fat (specific heat of about 2300 J/ kg K), 16g of protein (1500 J/kg K), and 3g of sugars/carbs (1200 J/kg K), and let’s say negligible ash, so we’re left with a weighted average of about 3280 J/kg K.

That’s within 10% of your assumed value, so I think I just wasted my time trying to check your assumption, which was pretty close to my number that took a lot more work.

But fundamentally there is less energy storage in a charged sodium atom than a charged lithium atom so it seems sodium batteries must always be bigger and heavier than equivalent-capacity lithium batteries.

Well the battery chemistry will always include much more than just the loose charge carrier of Na+ or Li+ or whatever cation floating around. It’s always a suitable cathode material made from other elements, too. Lithium ion batteries in cars today have cathodes mostly of high performance lithium nickel manganese cobalt oxides (NMC) or cheaper/more stable lithium iron phosphate (LFP).

The dominant sodium ion chemistry hitting mass production now uses Prussian Blue Analogues for the cathode (made from a 3d matrix out of sodium, plus a metal like iron/manganese/nickel, plus cyanide made from carbon and nitrogen).

Plus even separately from the raw chemistry of the battery, built in mechanisms for durability or longevity or charge cycles or thermal management or safety or other material properties may change the overall weight of the battery for any particular performance characteristics.

In the end, the performance of the entire battery is what matters, and lithium’s head start in less weight per cation may one day be overcome if the overall materials involved can be lighter in some as-yet commercialized sodium ion chemistry.

You got it all wrong.

An American oil company is going to have absurd windfall profits this year, because the global price for oil has skyrocketed while American production hasn’t gone down at all. So that CEO is warning everyone that he’s gonna have an extraordinarily large bonus this year.

California is famous for having different emission regulations. They have an exemption from the national law that they’re allowed to make stricter emissions and gas mileage regulations. None of those should prove to be a burden for anyone who wants to sell a battery EV in California, because there’s no standard that applies only in California to EVs.

Kia pulled its EV6 GT, which basically did not sell well in the US. They only manufactured that particular top tier trim level in Korea, but the other EV6 trim levels continue to be manufactured and sold in the U.S. (Wind, GT-Line). Kinda stupid that they named their top of the line the GT and the one just below that the GT-Line, but brands can be stupid with naming schemes sometime.

now both Hyundai and Kia have stopped selling EV models last year solely in the US

They’re basically one company and they stopped importing EVs. They still build and sell plenty of new EVs in the U.S., made in their plants in the state of Georgia. They’re also currently expanding capacity at their plants, in the hopes of catching more of the growing electric SUV market.

So they no longer sell the top of the line trim level of the Kia EV6, or the Hyundai Ioniq 6, but they’re still building and selling very similar models on the same platform. The Kia EV6 still exists in the lower trim levels, and the Ioniq 6N and the Ioniq 5 and 5N, and their smaller EVs (Kia Niro, Hyundai Kona) are still available, too. Both brands launched their 3-row electric SUVs in the US, too (Hyundai Ioniq 9, Kia EV9).

A lot of companies are slowing down their EV rollouts, but I wouldn’t say that Hyundai/Kia is the best example of that.

Average new car price has gone up a lot because the average new car has been purchased by rich people who demand high performance and luxury features. And rich people have been doing great the last 50 years, so the top of the market has totally run away with high prices.

If you actually dig into specific models and what they go for, you see that the most basic cars have only gone up slightly in price, but are also much higher performing (0-60 times, quarter mile times, braking distance), more efficient (better highway/city gas mileage), more reliable (more miles/years to failure), and have a lot more standard features that used to be expensive add-ons (automatic transmissions, power windows/locks, power steering), and are generally better constructed (smaller panel gaps, better sound proofing/vibrations), and much, much safer by pretty much every measure.

Today’s cars, even the cheapest ones, are much better than the cars from the 90’s, much less the cars from the 70’s (5-digit odometers because getting past 100,000 miles wasn’t necessarily expected, bodies that rusted within a decade of normal use).

So if a first generation Honda Civic in 1974 cost $3000 in 1974 dollars (inflation adjusted to $21,000 today), we should compare what that car was, compared to what a Honda Civic is today (starting at around $25,000 for the barebones model, $30,000 for a few nicer features). Compare torque/horsepower specs, actual performance at 0-60/quarter mile, gas mileage, all of that. I’m not entirely convinced that the people of 1974 were getting a better bargain on their cars than today’s new economy car buyer.

I hate that cars have gotten so big, and that the SUV is basically the American default at this point. But I don’t think that car prices have actually gone up that high in the 30 years I’ve been driving. And cars from before I was driving just…sucked.

Yeah, one of the issues I’ve read about happening for concrete failures was that some construction crews are under enormous pressure to salvage concrete that had been mixed too early, or delayed in pouring, or whatever, and where the concrete pouring characteristics cause issues (or crews add unauthorized water or things to slow down curing and then alter the characteristics of the poured concrete without the engineers’ awareness).

It’s wildly counterintuitive to those of us who don’t work in the space.

Yeah, the most prominent examples:

Motorola spun off its cell phone division (despite being the company that invented the cell phone and the clamshell cell phone) and sold it to Google, who sold it to Lenovo. So Motorola phones, under the Motorola Mobility name, don’t have anything to do with the radio and electronic equipment company that is currently known as Motorola Solutions.

Volvo spun off its car division and sold it to Ford, who sold it to Geely, and kept the truck business. So Volvo trucks are made by a different company under different ownership from Volvo cars.

River sand is the right amount of jaggedness to where it can pour and settle into the right density in cement to have the right strength in the finished concrete. Ocean/beach sand works, too, but needs to be rinsed with fresh water, and is usually pretty valuable where it is (for beach resorts and what not).

They’re testing for how to use different types of sand (desert sand, manufactured sand, recycled sand) and testing the pouring characteristics and resulting concrete strength, so that they can make reasonable decisions on when it’s worth using substitutes.

Exactly.

The whole reason why lithium is such a good material for cathodes in car batteries is because of its very low mass per cation. So for a Lithium Iron Phosphate battery, the the cathode material is LiFePO4, where the Lithium itself is only 4.4% of the overall mass of the cathode.

So it’s important to remember that although the lithium constitutes a small amount of the total mass of a battery, that swings both ways so that not much is actually needed to build the next battery out of recycled materials.

Your solar power storage expert is named Sun? Sounds lot like sun.

Maybe that’s why she became a solar power storage expert!

Also, I’d push back against the subtext that work experience gives skills. Plenty of people work a job for 10 years without having the adjacent job skills to be able to progress in that career or jump to another.

Critical thinking skills are the most important thing, and it’s possible to get a 4-year degree without actually picking them up or strengthening your skill sets in that area. But it’s also possible to work for 5 years without developing critical thinking skills, either.

In the end, no matter what you do with your time, only a small percentage of your effort is going into improving yourself. The people at work are trying to get stuff done for their employer, and the people at school are trying to get through the curriculum. It’s possible to do the work while the employer/school or even yourself cheats you out of the real long term benefits of actually learning during that time frame.

they could have bought a <$25k used EV last year and saved $4k with the EV tax rebate.

The people who were in the market for a car last year are by and large not the same people who are in the market today.

Plus let’s not forget, the actual EVs on the used market 12 months ago were different than today’s. Someone looking to buy a 3-year-old car today has to look for something originally sold in 2023, whereas 12 months ago they were looking at 2022 vehicles, with fewer models available and significantly fewer vehicles actually manufactured and sold.