Not that year, but they caused headaches for a giant group buy from a Chinese audio gear company that I was involved in. After a lot of wrangling and somebody knowing one of PayPal's vice presidents, they eventually got the funds released, but not before it made me decide never to trust PayPal again. I have not used them since then. No company should have that much power to arbitrarily restrict the flow of commerce.

My first thought was that the times when you have the most solar irradiance tend to line up pretty closely with when you need the most power for air conditioning, for the most part, but that's only true for the U.S. If you include Canada, where heat pumps have to do more work heating in the winter than cooling in the summer, that's not true.

So yeah, that's maybe plausible, if we end up using that much solar. On the flip side, if we could get past the geopolitical problems, having massive solar farms in South America for the North American winter and vice versa would solve that, too, and a lot more efficiently than what you'd get from using hydrogen even with transmission losses over thousands of miles. (You'd have only about 35% loss for a HVDC line from Canada to Chile.)

For that matter, pumped storage hydro is dramatically more efficient (70% to 85%) than hydrogen. So is pressurized air storage (also 70% to 85%). And both are a LOT simpler from a technology perspective than anything involving hydrogen, which means they are far less likely to fail, and if they do fail, they're likely to be less catastrophic (read "Oh, the humanity").

I just don't see hydrogen as a viable means of storing energy except in very specific niche cases where you absolutely have to carry an insane amount of energy with you and you cannot deal with the weight of batteries for some reason (e.g. aviation, maybe). For anything where you have a fixed ground installation, hydrogen is only worth doing if you would otherwise be wasting some thermal energy and cannot use it for some other more efficient purpose (e.g. the nuclear power plant hydrogen production example, where you could use waste heat for both splitting water and compressing the hydrogen). If you're starting out with electricity, it's really a non-starter, because there are just too many better ways to store that energy with far lower losses already, and there's no evidence after decades of research that it is even possible for hydrogen to ever reach a point where this won't be true. It probably would violate the laws of thermodynamics.

The only reason anybody is doing anything with hydrogen is because of buzz and available research dollars, IMO. It's a terrible way to do pretty much anything unless there are no other options for some reason, and after nearly a hundred years of trying to make this technology viable, IMO, we'd be better off writing it off as a failed experiment and moving on.

If you were viewing the sky from the center of the Earth, maybe. The main differences between bald eagles and satellites are altitude and speed.

Satellites are flying at a high speed at high altitudes, which means when you take long exposures from the ground, you get streaks from the reflection of the sun off of those satellites, and you'll get some of that that almost without regard to when you take the photo or where you are at the time unless you carefully limit your photo to a small area of the sky.

Bald eagles are flying at a low altitude and low speed, which means you'd be exceptionally unlucky for one of them to fly overhead while taking a photograph at night. And their low altitude also means they don't reflect the sun meaningfully, so in the unlikely event that one did fly over, it would be a slight dark streak, which is much less problematic than a bright white streak.

That's what most folks mean when they say that these satellites are cluttering the sky.

I think all the major credit card networks allow you to file a dispute for 120 days from the expected delivery date, which for an airline ticket, would presumably be the date of your flight. Even if you treat it as 120 days from the purchase date, you still should be safe booking up to four months out.

So no, you won't be the unsecured creditor. VISA/Mastercard/AmEx will be.

Ah. That makes even more sense. Guess you can tell I didn't RTFA. :-)

Airplanes are at least plausible. However, the volumetric energy density sucks, coming in at just 5.6 MJ/L unless you store it cryogenically, which isn't realistic in an airplane, compared with about 35 MJ/L for jet fuel. So if you're burning it, you'd have to increase the size of the fuel tanks by 6x. Fuel cells running electric fans are probably more efficient, and that efficiency difference might reduce that number somewhat, but probably not to break-even levels. Realistically, the efficiency difference is likely to be less than 2x, so you're still probably talking about probably a 3.5x to 4x difference in fuel tank size.

Power plants? Maybe, but only as a secondary power source by using waste heat from a nuclear plant to do thermochemical water splitting, and feeding that into a fuel cell.

As a primary fuel for power plants, it wouldn't be viable. The only way you get hydrogen is by splitting it from water or natural gas. If you split it from natural gas, you're better off burning the natural gas in terms of energy output per unit of emissions. If you split it from water, you're taking in more energy than you get back at the end.

In theory, you could use hydrogen power as a glorified chemical battery for storing power from giant solar farms and distributing it throughout the day, but in practice, you'd be better off using a battery at ~99% round-trip efficiency (assuming all DC), rather than a fuel cell at 30% to 50% round-trip efficiency.

I'm wondering how they keep the seawater from corroding the pipes. I understand freshwater nuclear plants without cooling towers. I'm terrified to think about saltwater for the outer loop. I mean, if it leaks, it's just hot water, so it isn't like it would be a nuclear disaster, but man, what a pain the backside it would be to go down for a year while you cut out and replace all of those pipes.

What caught my attention in this story, though, was that four reactors shut down, which means that two of them kept running. Not sure if this means that they clogged only a subset of the second-stage filters, and each reactor has a separate second-stage filter, or if they only partially clogged the second-stage filter, so some water got through, or if two of them have significantly different cooling, or if two of them have slightly dodgy sensors and probably should have shut down, but didn't. :-D

I'm guessing probably one of the first two.

Experimentally, with a 7,500 pound travel trailer, it's more like 115 miles, but it's still way short of a usable range when towing. The Cybertruck will never really be usable as a tow vehicle now that they've cancelled the range extender, IMO.

Alternatively, unless they have stopped doing it recently, Google has a mock interview program, where you can sign up and go through training that will help you get through Google-style interviews (which are not uncommon). Various other companies have similar programs, either free or for $$$.

There are a lot of advantages:

• Time to deployment. A drone can take off now. A piloted helicopter likely requires someone to drive to the helipad from home or whatever.
• Time in air. A drone never gets tired. It can stay up continuously until it runs out of fuel, stop for refueling, and take off again immediately. A pilot needs sleep, and there are only so many of them available.
• Number of simultaneous craft. Because you aren't dependent on having enough pilots, you don't have any limit on the number of craft other than their cost.
• Number of simultaneous craft in the operational area. Because the craft can pilot themselves using radar and dozens of cameras and whatever else, you can fly them closer together without worrying about the pilot's reflexes being fast enough to avoid a collision. And if you do have a collision, you don't kill anyone.
• Better accuracy because of ability to take greater risks. If no human would die, you can get closer to the fire to hit it more accurately if needed.
• Ability to do a continuous bucket brigade. Because you aren't limited by the number of pilots, even if you end up needing human pilots for the actual firefighting, you could still have fully autonomous helicopters doing all of the mundane flying back and forth to get water, and you could have them lined up a hundred feet apart for however many miles it is to the nearest reservoir, providing a literal continuous supply of water that would be completely unachievable with human pilots.
• Reduced weight potentially means slightly more water capacity, assuming you don't end up using up all of that saved weight with the extra automation hardware.
• Drones could potentially stay in the air 24x7 in small quantities to detect fires, and put them out before they become big.

There are probably other advantages.

Soylent Green?

I've read the articles, and I've gotten very close to installing home solar. Every article I've ever read says the same thing, which is that you try to get close to your average home power consumption. You don't size it massively larger. Because the power companies in California don't pay you if you produce too much power, and running up huge bill credits won't help if you don't eventually use that extra power.

And the folks storing extra power for backup aren't going to opt in to this sort of scheme anyway, because they won't want their batteries to be dead when they need them most.

Either way, even if you convince the people who overbuild the battery for backup purposes to sign up, none of what I said is wrong. Please, please tell me what I'm missing, because I *do* understand this VERY WELL, and I still don't see any plausible universe in which this isn't effectively just a storing energy with the same greenness as the grid except on days when dumping the extra power late in the day is immediately followed by a day in which the power from the solar panels would otherwise have been curtailed (which is the only situation in which that solar power wasn't already being used to make the grid greener).

The basic argument is that by not turning on a peaker plant, you're making the grid greener, but that falls flat when you realize that unless solar or wind power would be actively curtailed when you recharge the battery the extra time, that power used for recharging would not otherwise have been needed, and it has to come from somewhere, and if wind and solar aren't being curtailed, it comes from keeping some other kind of power plant online — natural gas in all likelihood.

It's a classic example of greenwashing. I'm sorry to be the bearer of bad news, but there's no such thing as a free lunch here.

Batteries shift load, period; except when curtailment is involved, they do not make the grid greener. Period. Batteries plus extra solar panels can make the grid greener, but the solar panels are what makes the grid greener. The batteries just allow you to spread the greenness over a longer period of time. And yes, when you have so much excess solar that you get curtailment, batteries are needed for some of that solar to make a difference, but that's the *only* time batteries make the grid greener, period.

First, people probably won't ever live an average of 100 years. Second, you don't need a stable demographic profile. There's exactly no advantage to having elderly people onboard initially, for a number of reasons:

• Food production probably won't be able to be at full speed on day one unless you start the process long before you take off.
• Older people are less able to learn the new skills that they would need to be able to do repairs on the ship, etc., and are less likely to already know those skills.
• Older people are less able to do physical labor than younger people, and will therefore be more limited in their ability to contribute.
• Older people have fewer years to contribute before they stop being able to do so entirely and become a burden on the ship's limited resources.

I mean, if you want to all but guarantee that the younger folks turn sociopathic and throw the elderly out the nearest airlock on their 50th birthdays, a great way to start that story is by creating the generational ship with people of every age from day one, so that from the very beginning, they resent the elderly. If you actually want them to retain their humanity, you'll almost certainly want an upper age cutoff on the folks who go up in the initial wave.

And even if you decide that the cutoff should extend beyond child-bearing age, you sure as h*** don't want to bring twenty-four 90-year-olds. Half of them probably wouldn't even make it to orbit, and that's also not an accurate picture of normal demographics. There are fewer and fewer people the older you get, even if you ignore population growth, because some people die before they get to that age.

Over time, you want a fairly even distribution of age, but that will happen on its own. People don't turn 25 and suddenly say, "I want a baby." They have kids at different times, based on what's happening in their lives. Some won't have any kids at all. Some will have kids later in life. That means that the distribution going in doesn't really predict the distribution going out. There's a lot of entropy at work.

It probably does help, however, to have a roughly even percentage of people at each age throughout the age range where people typically have children. You don't want everybody to be 18, and you don't want everybody to be 45. As long as you have roughly the same number of people at each age within roughly the primary procreative band (ostensibly 18 to 60 for men, 18 to 45 for women, so probably pick the narrower of those two bands), you should end up with a fairly consistent rate of childbearing, in all likelihood.

It may also be problematic to not have children on the ship, because you would see a huge dip as though there had been no new children born for 20-ish years, and by definition, that wouldn't smooth out until about twenty years after the original crew dies. There are, of course, ethical questions about whether it is okay to do this, because kids aren't old enough to understand what's happening, and wouldn't really have any say in the matter, so it could also be problematic if you do have children on the ship, just in different ways.

On the other hand, not having any school-aged children for at least the first five years means more time to spend preparing the habitat for future increases in head count, building spare parts out of raw materials, leaning how the ship works, coming up with rules and procedures to ensure that things run smoothly, etc. And the only real disadvantage would be that it would take two decades before you would start having replacement people who are old enough to do useful work, which is probably fine if you cap the age at 45 or so, because by the time they're ready to retire, you'd have the first batch of replacements, and you probably won't lose *that* many people in the first twenty years. So the only big impact you'd expect from not starting with children onboard would be a 20-year-long dip in mortality when the oldest of the original crew reach their typical lifespan.

So really, I'd say that it's critical to be evenly spread across child-bearing ages, and that's probably the only thing that really matters much.

You can't count that power twice. Even if you assume that every drop of power that goes into the batteries comes from the solar panels, you're still taking away power that would otherwise have been sold back onto the grid, which means using some other non-solar power somewhere else that would have otherwise been solar power.

Put another way, before this change, every drop of the power produced by the solar panels (ignoring curtailment, which by definition this can't change, because batteries can't be charged beyond full) was either being used by the household, going out onto the grid to make the grid greener, or charging the batteries for later use to make the grid greener.

To the extent that this charging was already occurring, the shift in utilization of the battery's output means that the power that otherwise would have gone to the household from the solar panels later at night would come from a dirtier grid power source (except to the extent that the household wasn't running down its batteries fully, which while possible, is rare).

To the extent that the charging was in excess of what came from the solar panels, again, that power came from the grid, at grid levels of greenness.

So regardless of whether you're looking at the power that appears to come from the solar panels or the power that comes from the grid in excess of the solar panels' capacity, the power effectively is no greener than the grid, with the sole exception being situations in which *all* of the following are true:

• The customer's battery storage is so massively overbuilt that they typically don't run it down with their own usage before their solar panels start recharging the batteries the next day.
• The customer's solar panel array is sufficiently overbuilt that it can fully recharge the battery in a single day.
• The extra power dumping occurred the evening before a day in which the excess power would have been curtailed.
• The customer's charging software isn't already selling back that excess power at night for arbitrage purposes.

One could reasonably ask why such unicorn customers are paying PG&E for grid-tie operation in the first place — all three or four of them.

You don't take 2400. You take probably more like 800 people of child-bearing age, ideally pre-coupled. You have a two-children-per-family policy, i.e. when the first generation are born, you have about 1600 people. By the time the third generation is born, the first generation are starting to die off. You keep safety margin for the occasional happy accident.

Besides, you have to build everything to handle significantly more people than you plan to have, so that if some piece of equipment fails, everybody doesn't die. That margin should be big enough that you'll never have to worry about such things unless you didn't plan correctly.