Yes, you need a lot of energy. Per this NASA presentation, wheat can produce up to 1.44 grams of dry mass per mol of photosynthetically active radiation. Using wheat's harvest index of 0.55 that's 0.792 grams of human-edible biomass per mol of PAR. To supply 2000 calories (kcal, food calories) you'd need 607 grams of human-edible wheat grown from 767 moles of PAR.
One mol of 630 nm photons contains 189 kJ of energy. You might be able to produce it from red LEDs at 45% efficiency. (767 * 189) / .45 = 322140 kJ of energy, e.g. 89 kWh. At average industrial prices of 6.74 cents/kWh in the US, that is $6.03 just for electricity costs. That'll provide one sedentary adult with enough calories each day until nutritional deficiencies catch up with her. Want to feed the masses? American electricity consumption per capita is about 33 kWh/day; putting America on a vertically-grown-food diet would nearly quadruple that. (No, the savings on long distance food transportation don't come even close to cancelling out that enormous increase in electricity consumption.)
Vertical farming makes sense for high-value crops that supply more in the way of sensory experiences than calories: cannabis, fresh herbs, fresh salad greens, delicious tomatoes that don't need to be bred/harvested for hardiness during storage and long distance transport. It doesn't make economic or ecological sense for supplying people with the bulk of their caloric requirements.
]]>It's a bit like boasting about full employment of agricultural labourers in the mid-seventeenth century. On the other hand a pair of nuclear reactors can be operated by a couple of hundred staff to produce about 15TWh of electricity annually.
The growing employment numbers you see in solar/wind right now are mostly an artifact of rapid expansion. American net coal capacity growth is negative right now and all you see is the operational labor; solar/wind are growing quickly and what you mostly see are the temporary construction jobs. Plus of course there's rooftop scale solar labor mixed in with the numbers for utility scale, while the latter is significantly more productive.
In the US, utility-scale solar with good solar resources is thriftier with labor than a new nuclear reactor.
New AP1000 reactors at Vogtle, assuming 90% capacity factor: 2.5 real MW/full time employee (800 permanent jobs to be added for units 3 and 4, 1117 MWe each, 90% capacity factor)
The Desert Sunlight solar farm generated 1,346,282 MWh in 2016.
https://en.wikipedia.org/wiki/Desert_Sunlight_Solar_Farm http://www.firstsolar.com/Resources/Projects/Desert-Sunlight-Solar-Farm
Desert Sunlight has "up to" 15 permanent jobs associated with it. There were also 440 construction jobs over a 26 month period for Desert Sunlight -- amortized over 25 years, that's like another 38.1 permanent jobs.
If you include only the permanent jobs, Desert Sunlight generated 9.8 MW/FTE in 2016. Add in amortized construction labor and it's at 2.9 MW/FTE. Vogtle 3&4's productivity/worker will also fall if you account for construction labor, though that labor pays back over maybe 60 years rather than 25.
]]>There's no way that planetary civilization is going to decarbonize fast enough to stabilize climate with emissions cuts alone. Active carbon dioxide removal measures are going to be required in the later 21st century. So if we're positing a 2117 that's not just skidding toward the big Final Collapse, the good news is that we don't need to invoke hard-and-fast rules like "the last drop of fossil oil is burned in 2050." The difference between top speed decarbonization under the Deep Green Planetary Dictatorship and a lackadaisical effort by Competing Cleantech Capitalists is more degree than kind. If we wanted to stabilize things with purely passive measures the opportunity already passed.
The end of the age of mass-participation labor is a biggie. Weak post scarcity is... something like hunter-gatherer life, before they encounter Malthusian limits or charismatic jerks wanting to build temples and polities? But you get to gather orbital launchers and semiconductors from their respective strange new trees, along with the fruits that humans could gather from the trees of pre-antiquity.
]]>Nah, the "push-polling" aspect I object to is focusing on this rare edge case for discussion with the general public. Actual safety/insurance experts are (hopefully) thinking with numbers. But keep running stories about this one unusual aspect of SDV safety (and I have seen it crop up repeatedly in general-circulation publications) and the availability heuristic is going to slant public thinking of SDVs more toward "the technology that can kill you for the greater good" instead of "the technology that can save your life when you're impaired by fatigue", even if the latter would be a much more common outcome.
As a parallel example, cognitive biases are going to make many people mis-evaluate the desirability of airbags if you provide them with statistics about how many lives airbags save and follow it with multiple humanized stories or discussions about people killed by airbags in freak circumstances or in cases of manufacturing defects. People who don't think quantitatively (and that's most of them) are going to privilege concrete stories over statistics. The public can be misled by a pattern of publication/discussion even if every individual story or discussion is truthful. There's no need to outright lie to people to scare them away from something; just keep harping on the scary aspects (no matter how rare compared to the good parts) of a proposal.
]]>Even people who swear black and blue that they would die themselves rather than mow down 30 people in that scenario (it was a similar one but you get the point) baulk at having a driverless car make that decision for them (they were asked what they would do then asked if they would accept a driverless car making the same decision and it was an overwhelming 'Hell NO!'
I would guess that the same sort of push-polling could be used to turn people against trolley cars if you really wanted to. Just warn trolley-fans that they might be shoved onto the tracks at any time if there's a runaway car and any utilitarian philosophers with a poor grasp of physics in the vicinity. The actual chances of a SDV facing a kill-the-occupants-or-30-bystanders scenario seem roughly on par with a trolley-stoppingly-large fat man being available on a bridge over the tracks.
Present such utilitarian dilemmas enough times and the subjects will just learn to be wary of maniacal philosophers bearing contrived scenarios and cackling "intuition pump!"
]]>The disintegration of the former USSR, and subsequent handover of the good pieces to looter-oligarchs, cut CO2 emissions faster, deeper, and for a longer time than any nation's subsequent planned reductions. Richard K. Morgan's Market Forces satirically imagined what life would be like if globalized looter-oligarchs took climate change seriously and kept expanding their power at the same time. (Not a very good book IMO, and I like most of Morgan's others, but it is amusing/frightening to imagine what happens if the billionaires decide to stabilize the climate their way.)
]]>You'd need to be sure that there's a mutual "disarmament" of reserve dispatchable generating capacity on both sides if you want to ensure that everyone's interests remain aligned toward keeping the system running. Otherwise, the first big spat that in the past would have spurred {sanctions against Russia, Gazprom sudden price renegotiations} will be conducted via abrupt shutoff of electricity flow in one direction, hardened against retaliation with local dispatchable generating capacity. At least fuels can be stockpiled locally in multi-month quantities.
AIUI the problem with doing SPS incrementally is that the size of the microwave spot is inevitably going to be large at the ground whether your geosynchronous microwave source is generating kilowatts, megawatts, or gigawatts. If you wanted to supply Alaskan remote villages with a handful of megawatts each, you'd need to build practically the same gargantuan ground stations that you'd use for supplying a Chinese conurbation with gigawatts. If I'm wrong I'd love a pointer in the right direction.
]]>'Tis a bullshitter's book in the glorious tradition of The Poor Man's James Bond and The Anarchist's Cookbook, with somewhat more academic language to snare people who know a little (but not a lot) about chemistry. The best written information on the manufacture of explosives and chemical warfare agents was and is published by governments and academics. It used to be somewhat occulted because your rando crank didn't know how to effectively search the holdings of a large academic library, but nowadays it's all digitized anyhow and keyword search works the same as it does for the larger net. HathiTrust, archive.org, Google Books, Google Scholar, BookZZ, sci-hub: there's a wealth of tools out there for identifying and/or obtaining specialized books and documents. A lot of the Deep Old Knowledge of practical chemistry from before ~1960 that's still resting untranslated in German and French is now accessible to non-fluent chemists via machine translation. (Yeah, the translations are still so-so, but the monolingual chemist has enough domain knowledge to make sense of the output despite fractured phrasing.)
]]>Do you have a citation for that? AIUI stable gases are pretty well mixed throughout the troposphere. The heavier ones don't pool near the bottom any more than the sugar dissolved in a rum and coke falls to the bottom of the glass. Like sugar, water, and alcohol they're all mutually miscible and don't spontaneously separate. (True, helium is light enough to reach escape velocity in the uppermost near-vacuum of the atmosphere and xenon isn't, but that's not the same thing.)
I agree with Dirk that critical cryogenic applications could be supplied by reverting to atmospheric extraction of helium. As an intermediate step I expect to see better efforts at recycling in cryogenic applications. For an example of what happens when an exotic gas suddenly gets much more expensive, read about what happened to neon pricing and uses in the wake of supply crunches due to Ukrainian fighting.
]]>Solar power satellites? Well, they look a little more plausible than without the BDB's existence, so there's that. But past waves of enthusiasm about SPS crested in situations where maximizing power output per cell was more significant because solar cells were a lot more expensive. Now crystalline silicon solar cells are cheap and batteries are... not cheap, but still cheaper than I can make SPS look even with hopeful squinting. Crystalline silicon is cheap, abundant, and efficient as PV materials go so it's great for terrestrial use. But it's not very tolerant of charged particle radiation damage, which means it's not a good fit for geosynchronous orbit where SPS would ideally be located, which also means that space-solar doesn't automatically ride the falling cost curve alongside terrestrial solar.
]]>To put it another way, if a story becomes uninteresting after readers know the major plot points, it's not all that interesting in the first place. I don't seek out or propagate "spoilers" deliberately but they don't much hurt a good story. Works worth re-reading hold up whether they are already spoiled (either by the early pages of the work or by another reader) or not. I know what happens in The Amazing Adventures of Kavalier & Clay. It's rewarding to re-read anyway.
]]>You can order sodium sulfide online as a darkroom chemical, buy calcium polysulfide solution ("lime sulfur") intended for pest/fungus control on trees, or make sodium polysulfide at home by stirring calcined sodium bicarbonate into molten sulfur. Any one of these three will release copious quantities of hydrogen sulfide on exposure to an acid solution such as lemon juice. Hydrogen sulfide is roughly as toxic as hydrogen cyanide by inhalation, quick acting, and gives little-to-no pain as "warning" on the way to unconsciousness. It stops stinking once the concentration gets dangerously high. That's why it can also be so deadly in industrial accidents.
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At a crude guess, it appears like the half-life of radioactive materials is somewhere around 500-1,000 years.
See the problem? There is no single half-life of radioactive or of cultural materials. How many of the Ten Commandments have been lost in the past thousand years? None of them. They're highly conserved. They're not just lucky atoms that have managed to survive many generations of decay by sheer chance, like the last 0.00001% of a polonium sample. In the CRC Handbook of Culture and Posterity they are currently listed as "observationally stable."
Newton's laws of motions, Napier's logarithms, and the calculus are likewise cultural materials with much longer half lives than most things first published in the 17th century. The continuing survival of that knowledge doesn't rest on whether they published at the time via acid paper, rag paper, or clay tablets. If there is a good argument for the eventual forgetting of common mathematical and scientific knowledge, it's not one that can be extrapolated from observations of how we lose old email and personal photographs.
]]>What I find more interesting/useful, though it's still focused on fresh produce rather than staple crops, is the solar powered seawater desalination plus greenhouse growing of Sundrop Farms in South Australia.
Desal and Solar Prove the Perfect Tomato Source
In the two months since it started growing its 440,000 climbing truss tomato vines under 20ha of glasshouses, foreign-owned Sundrop has used no fresh water from rivers or underground aquifers, no pesticides and, once its solar thermal tower is commissioned, will use 90 per cent renewable solar power, heating and cooling that it has created on-site.
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