Also it's not "really" hard. Think of subtractive notation as a way to write down what's really an int1 - int2 expression in normal roman numerals, with the out-of-order characters representing int2. To add these together, (A1, A2) + (B1, B2) = normalize(A1+B1, A2+B2) where those additions are a little easier. The normalize step is not very complicated; it basically says "if a letter is repeated on both sides eliminate one instance of it; if it is not but there are too many on one side, adjust the other side to compensate." The only nuance is that "too many" for the left hand side is "four" whereas "too many" for the right hand side is "two."
How do you think the hydrogen is produced? Currently it's either a product of petroleum or produced by using electricity to split water. So your argument of electricity not inherently being clean energy applies to hydrogen as well.
Assuming you use electricity to split water to power your fuel cell, you've basically just made an even more complicated way to use electricity to power your car. So at that point, just simplify it and just use a battery and a motor.
Small nit to pick, its produced more from steam reformation of methane:
"There are four main sources for the commercial production of hydrogen: natural gas, oil, coal, and electrolysis; which account for 48%, 30% 18% and 4% of the world’s hydrogen production respectively."
My understanding is that it's just talking about the pumps. 95% of the energy from the battery is turned into rotational energy by a motor in the pumps. This pushes the fuel into the reaction chamber of the rocket engine. Contrast this to a gas-generator cycle that uses some of the fuel/oxidizer to run the pumps. It's not perfect combustion (you don't want it to get too hot) turbines aren't perfectly efficient, etc. so you only get 50% of the energy out of the fuel that you use in the turbo pumps.
However, batteries are heavy. I'm hesitant to believe that electric pumps will scale well to larger rockets, but I would love to be proven wrong.
My guess is that the vanes on the top do something to disrupt the wind and stop it from reaching street level at such high speeds. The vines growing between the vanes could prevent this effect from happening.
Since we are discussing Tesla solar roofs, they suggest your installation comes with a PowerWall, thereby storing power during the day to use at night. I personally don't think we are there yet, but I think the goal is that you don't need the entire national power grid just for night electricity, just a big battery.
Batteries + roof PV, is far more expensive on a per-watt basis, then a power grid + utility-scale generation.
"Just buy a $15,000 PowerWall, which you will need to replace every 10 years" is, compared to grid electricity, incredibly wasteful.
There's a reason why customers and users overwhelmingly prefer centralization, even if its harmful for them in the long-term. It's cheaper, and people would prefer it to be someone elses' problem.
Have you done the math? If net metering didn't exist, my back-of-the-envelope calculations say it would probably break even in California. With net metering, sure, it's pointless.
My parents pay $1,200/year for electricity, in a fairly large house. Given the expected lifetime of a power wall, that will eat all the 'savings' of living off the grid.
There's also the matter that if, say, 40% of the population disconnects itself from the grid, that doesn't mean that the cost of maintaining that infrastructure will drop by 60%. Someone will have to pay for it.
Where are you getting $15,000 for the powerwall? It's $5,500 for 13.5kWh, which should be enough for nighttime loads in many houses (but may require some inconveniences, like not running the dryer at night).
You are right that it does not yet work out, it's $0.17/kWh for the powerwall (assuming you fully charge/discharge it each night) + cost for panels. Given that grid-disconnected users would want some buffer, an off-grid system probably works out to ~$0.40/kWh all in for battery-stored electricity
You could save a big chunk of this by some habit changes, most of the cost comes from the batteries, so scheduling energy intensive activities to run during the day reduces your cost for them to $0.10/kWh or so.
Honestly I am surprised how close these numbers are. I initially was sure the grid would survive in cities, but now I am not so sure. In 10 years these numbers will likely be half what they are now (batteries in particular will be way cheaper). It might all be enough to kill the grid in many places.
That was a great read, thanks for providing it! It's interesting that they mention studies in mice about using radiation to cure cancer. Sounds like the beginnings of the discovery of chemotherapy.
It's a trade off. In my opinion when using rebase you don't lose history or make it inaccurate. A bug would still be introduced by the commit that made it, so tracking down bugs with bisect or other tools works the same. The main advantage is that your history is much cleaner.
