avernon · HackerTrans

3 jaar geledendiscuss

Hub and spoke is primarily used to fill large planes. If you have 10-20 passenger electric planes you'd land at some random county airport, eat a hamburger or a taco while the plane recharges, then get back on the same plane and finish the trip. So you'd have a layover like hub and spoke but all the concerns about missing connections go away.

avernon

3 jaar geledendiscuss

Yes, I read the underlying paper a while back. It only looks at the very first step of a Dow-like process, before any electrochemistry happens. Instead of dumping hydroxide in a tank, they expose it to hydroxide in a serpentine flow path. When I was reading into this before calcium didn't seem to be too big of a problem for the Dow process because the calcium compounds are more soluble than magnesium hydroxide. They were actually adding more calcium with the lime. So their comparison may be to a different method than the Dow Process. It didn't seem particularly useful.

Then you neutralize the magnesium hydroxide with hydrochloric acid to make Magnesium chloride and do molten salt electrolysis on it to make pure magnesium and chlorine.

avernon

3 jaar geledendiscuss

They mention that they are doing electrochemistry. A huge portion of historical magnesium production is from electrolysis, including the only operating plant in the US. Past methods have used lime to precipitate magnesium (Dow) or evaporation ponds to concentrate it (the current Utah plant). Probably the new thing they are doing is using something like Chlor-Alkali to make base that precipitates the magnesium instead of using lime. Then the electrolysis of molten magnesium salts would be similar to products of today. There is some chance they have improvements in these areas, but there are really only so many options. The job descriptions they've posted support this hypothesis.

Recently most magnesium comes from China. They mine ore, throw it in a coal-fired furnace along with some reducing agents, then collect pure magnesium vapor. This process is more labor and energy intensive, but has significantly less CAPEX. Works for China.

Chlor-alkali is more expensive than lime and the back-end electrolysis is more expensive than thermal reduction. So I'd be skeptical they are going to lower costs without some kind of CAPEX reducing magic for molten salt electrolysis.

avernon

4 jaar geledendiscuss

In this case it is boil sodium, condense sodium to heat air, run air through turbine.

avernon

4 jaar geledendiscuss

Quaise wants to use old coal plants. So yes if you can drill down super deep to hot enough temperatures.

avernon

4 jaar geledendiscuss

Will your system be robust to changes in solar farm design? Like if the industry goes towards the Erthos model of installing panels on the ground without racking or trackers?

avernon

5 jaar geledendiscuss

Germany has a 220 euro/kWh feed in tariff subsidy for geothermal.

avernon

5 jaar geledendiscuss

Drilling cost is usually estimated for drilling in sedimentary rock with assumptions about how casing is run ;)

It is possible that drilling 30,000' of granite has conditions that make the estimation model irrelevant. 5 km isn't really deep enough, anyway. My next post will cover the thermo. It is pretty dang hard to get down to anything approaching $50/MWh. Definitely need more than cheap drilling.

avernon

5 jaar geledendiscuss

Tesla was founded in 2003, Rivian in 2009. So Tesla took five years to start Roadster production, while Rivian has taken 12 years until first customer deliveries. Maybe Rivian will ramp faster. Sam Korus tracks the numbers and so far Tesla is ramping faster than Ford, making it the fastest ramping car manufacturer in American history. I wouldn't be surprised if some Chinese companies could go faster. It is much faster than what Toyota did. They are very methodical, which is why they have almost zero pure EV sales.

avernon

5 jaar geledendiscuss

The data is observational, which generally means you should ignore it. It is too noisy.

There were those studies that showed moderate alcohol use improved health and only heavy drinkers saw detrimental health effects. The problem was that "no drinking" group included people that weren't drinking because of poor health. Later studies compared drinking vs. a "no drinking" sample of people that drank around two glasses of wine per year. The improved health effects completely disappeared. The more you drink, the worse it is for your health.

So this study is like that in using a potentially unhealthy comparison group. They try to offset that a little by also throwing in people that quit drinking. But it is likely that some people quit drinking because of health problems. So I'd guess that this study has the same problem with an unhealthy comparison group. The study probably can't tell you what the actual relationship between alcohol use and dementia with any authority.

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