CaptainPanic

To create power with steam, you do not need temperatures associated with molten rock. A much lower temperature (i.e. a few hundred degrees Celsius) is also still acceptable. Volcanic power is used at quite a large scale. Iceland has a LOT of these power stations. However, it is much better to drill a hole a few kilometer away from the volcano than to use the slope of the active volcano itself. The temperature is still sufficient, but the rocks are more stable.

It can definitely be interesting to build two separate infrastructures, although I believe that the separation that people want to make is between dirty water (i.e. waste water from households) and rainwater. The rainwater may be used for irrigation, but also for flushing toilets. While forest fires are a real problem, you shouldn't underestimate the amount of water used for flushing toilets on a global scale.

Wikipedia has a list of unmanned urban metro / subway systems. Those are local trains, right? https://en.wikipedia.org/wiki/List_of_automated_urban_metro_subway_systems

Do not use your elevator shaft as a drainage pipe. I do not think that we have to discuss that at length. However, making sure that not all the water hits the sewers at once is a major change in thinking. Not too long ago, cities were built with the philosophy of removing rainwater as soon as possible. Drainage canals were made as straight as possible to give the water the quickest way out. And that works really well as long as these canals do not exceed their capacity. The new philosophy is to create intermediate storage for the water. If all rainwater hits the sewers during extreme rain, these are almost certain to flood. So, you have to store it first, and release it into the sewers in the hours/days after the rain. In the Netherlands, a lot of progress is made. Take the "water square" for example: http://www.urbanisten.nl/wp/?portfolio=waterplein-benthemplein A square which is used for recreation (relaxing and skating) most of the time, but which can store thousands of m3 of water if needed. Dutch cities are all replacing asphalted and paved areas for grass, which absorbs more water. Cities are building creeks and other drainage systems, which are deliberately not straight, and not only add to the capacity to remove water, but also stores water while it rains.

You should give us some more boundary conditions of your assignment. A good economic analysis of the production of a chemical is quite difficult! It involves a comparison of multiple reaction routes, and includes an estimate of the costs of the factory for all routes (investment and operating costs). I kinda doubt that your assignment is that complex. Have you found any papers yet that describe the reaction routes? Maybe you can post the links you found so far here, then we can point out what is important in those. But please do not expect us to do a literature search for you. That is your homework, not ours!!

Guys, my question is answered, with some extra's as a bonus! Thanks! Of course, if you're interested to continue a discussion, feel free!

The first that comes to mind is the regular smoke machines that are used in clubs and parties. Those are not as hot, are not very dangerous and can be turned on and off at will. Seems ideal for you? You can also use a search engine to look for mist makers. These are tabletop gadgets that make a little mist. Some can be so small that they can be integrated in a small scale decor for a tabletop roleplaying game. Finally, some people use frozen CO2 (dry ice) to create "smoke". It has the benefit to stay close to the ground, giving a spooky feel to it. Essentially, you locally make air very cold so that the water in the air condenses and form a very small fog. Cold air is denser, so that's why it sticks to the ground. Not sure at what scale you need the smoke, and whether people need to stand in it. CO2 comes with some safety issues (it can be toxic at higher concentrations!!) so be careful with it if you make it big.

This is exactly why I posted here. Thanks! In our discussion, we were arguing whether the Kerbal Space Program solar system would be possible at all. We'll just ignore whether interstellar gas clouds want to form such solar systems at all, but just assume they did and now we want to check whether this solar system makes any sense at all. So stars could possibly be much smaller, but burn as bright as our Sun. In the Kerbal Space Program solar system, the central star is also scaled down, probably with a factor 10 (I think in radius!), but it shines like our own Sun. Under the assumption that this is governed by a smaller gravitational constant, I read that this would be actually expected. Also, assuming the universe is as old, heavier elements should (start to) become more common than in our universe. The game predicts very little about this, but it is interesting to know! Would elements heavier than iron also be expected to be more common? Anyway, thanks for helping out in our pub discussion! Much appreciated!

Actually, you'd be surprised how politically neutral Kerbal Space Program is. No mention of any POTUS, or even of countries.

Hey all, It’s been too long since I showed my digital face around here! But I am stuck on a question and this seems the #1 place to get some quality feedback, so I dug up the password and logged in. All is well on my end, hope you’re all doing great too. Tl;dr Other than gravity itself, orbits of celestial bodies and the attraction of objects (i.e. people) to the celestial bodies, what else would be affected if you change the gravitational constant from 6.67*10E-11 to something a lot larger (say 6.67*10E-9)? Longer version In a fantasy universe, such as exists in the Kerbal Space Program universe, planets tend to be 10x smaller than in our real-life universe and solar system. The reason that the programmers did this is to make the gaming experience nicer: you can orbit a planet in just 30-40 min, rather than hours. In a pub discussion, we were discussing how the physics of this would work. The gravitational acceleration at the surface seems unaffected, and is still something around 9.81 m/s2. Since the planet is so tiny, you’d expect that the gravitational acceleration at the surface is much lower. But it isn’t. So either the planet is incredibly dense (maybe some fantasy-elements in the core?) or the actual gravitational constant (G = 6.67*10E-11 m3 kg-1 s-2) is different in this universe. Of course, in a fantasy universe, you can write whatever you want. Kerbal Space Program is just a game, and the programmers have total freedom. But if you’re expanding the game to include more models of physics phenomena, would you run into problems because the gravitational constant is different? The orbits of planets and my space ships are stable, so those would work with a different gravitational constant. But would there be any other phenomena in which the gravitational constant plays a role? p.s. Kerbals are one of the reasons for my inactivity here. Been rather occupied launching rockets. That, and life just got busy in general.

In my family, it was figured out the hard way: by digging into the old sources, such as tax records, marriage documents and registration of houses - those date back sometimes hundreds of years (at least in the Netherlands). Typically, it is rather easy to trace it back as far as the time of Napoleon, since Napoleon (or rather his officials, not him personally) kept pretty good records. Beyond that, you gotta be creative and get lucky.

I suspect that despite the article's title calling this "large scale", the Chinese consider this 200 MW plant a 'pilot/demo' plant. If proven to be economically and technically feasible, their idea of "large scale" may just be a little larger than we realize. I would suggest you look at this regarding the price (which is closely related to the usefulness) of the land you're using. If you place this in the Gobi desert, which is largely uninhabited, and non-arable, nobody really cares if you use lots of land there because it has no (or very few) other uses. The Drax powerplant is located smack in the middle of a densely populated and cultivated land. It's actually using up land that could easily be used for many other purposes. The main issue of the location is that you must transport that electricity to somewhere else, which comes with its own investment and energy losses. I wonder how robust and efficient the Chinese electricity network is. It's mostly quite new, but it is a topic that I don't see a lot of news about.

This thread is ancient (it started in 2008), but it appears this is the first actual Air trecks built... even though their name is Razerblades, rather than airtrecks. Congrats to the creator (named Charles). Check out that website, it is worth it.

Destroy humanity (and leave the rest of the planet alone): probably easiest with a virus? Nuclear war might be another option. Destroy all life on our planet (but leave the rocks alone): you'll need more than all the warheads on our planet. But building many many many more warheads might achieve it. An asteroid of 10 times the diameter of the one that finished the dinosaurs too (but I didn't do the math, so if you wanna make sure, get an even larger one). Break our planet apart (but allow it to settle back into a new planet): smash something the size of our moon into it. Break our planet apart permanently: either slow it down enough to make it fall into the sun (you can calculate the kinetic energy you need to overcome), or smash something incredibly large and fast into it. Janus gave you an answer a few posts above, but I am not able to check it. But since the question was not clear: I advise all of the above.

Harold Squared, In this thread, you made a lot of claims, and explained a number of ideas. And people asked you a bunch of times if you can show any evidence about how this is supposed to work. When people ask that, it means you show some publications, or some studies, or some research papers, or even some news articles that back up your claims. It does NOT mean that you must explain your idea a little better, as you have been doing until now. The joke about the unicorns was quite serious. Of course, people here know unicorns don't exist. But until you start showing on which underlying assumptions you have based your claims, your story is just as good as the one about unicorns.