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.

It’s for showing off the engineering. Lots of robotics competitions focus on different things (throwing balls, kicking soccer balls, moving fast), but BattleBots is definitely the one I’d be most worried about advancing a dangerous line of killer tech.

A humanoid bipedal foot race shows off balance, speed, power efficiency, and things like that.

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.

Kinda depends on the rock, right?

Starship has charged $90m so far. That’s including a healthy profit I’m sure.

SpaceX has a contract with Voyager Technologies for a 2029 launch at $90m. I would read that in the opposite direction as you, where you assume that it’s costing SpaceX less than what they’re charging. That’s far enough away that I’m not sure they’re going to be able to keep that price or be certain that they can actually launch on time or make a profit at that price.

A gravity storage system that stores about 100 MWh and outputs about 25 MW is much, much larger than the 65 battery containers they’d replace. It stores basically 4 hours worth of energy in what appears to be a large steel and concrete structure 150 m tall (the equivalent height as a 30-40 story building) on a 100m x 100m footprint.

If we’re talking about storing a terawatt hour, then we’d be talking about about 10,000 of these gravity storage systems needing to be built. That’s what I mean by existing technology not really meeting the scale requirements of the problem.

Gravity storage systems all basically suffer from this problem. Water-based solutions need to be sited on favorable geography to have large scale (otherwise water itself isn’t dense enough to compete with concrete and stone and sand).

Meanwhile, storing the same 100 MWh of energy in containerized lithium batteries would basically require a 4x6 stack of 40-foot shipping containers that each can store 4MWh.

We can get there on storage, but we’re talking about decades of planning and implementation, across all technologies, before we can even credibly reach storage representing one whole day’s electricity usage. How many man hours of labor does that engineering and planning and building represent? How much steel, energy, and machinery would these projects use up?

Anyone who talks about this stuff without recognizing the scale involved is basically not serious about solving it. It’s an engineering problem that exists independently of money (and it’s also a money problem, but that part will probably pay for itself because of how valuable a solution to this problem would be).

We have the storage technologies, the only thing missing is money.

When discussing large public projects whose scale is larger than anything before seen, the money is mainly an accounting placeholder for the real resources that need to be expended.

Grid scale storage has been expanding at an exponential pace, but the sheer magnitude of the materials and engineering work that needs to be done to make a dent is pretty huge.

Bloomberg projects that total cumulative installed capacity should hit 2 Terawatt hours by 2035, noting that would represent 8x the number for 2025. But when you compare those numbers to just how much electricity is produced or consumed, with 22,000 TWh per year, we’re talking about demand periods measured in minutes, not even hours, much less days.

At scales large enough to make enough of a dent to show up in global energy stats, we need to recognize that even infinite money would run into the real resource constraints of how much capacity we as a species have for pulling minerals out of the ground, processing them into useful materials, and engineering them to be useful energy storage solutions (whether pumped hydro or other gravitational systems, compressed air, flywheels, or whatever battery or fuel cell chemistries can store energy in an efficient way).

We have some technologies, but need things to improve significantly before storage can actually meet the needs for power that meets demand at any given moment in time. In the meantime, matching supply and demand in real time is a true engineering challenge, not just a monetary challenge.