Comments by "robheusd" (@robheusd) on "Real Engineering" channel.

  1. Yep. The economics of hyperloop are bad. That is because you have to calculate the average reduction of travel time for all journeys in which taking a hyperloop makes sense, in comparence, with alternative forms of transport. Total travel time includes the time you spent in slow transport reaching a station for hyperloop, and to final destination, and the time spent on boarding a train (safety measures will add significant time). This is bad for hyperloop as hyperloop stations will be on average further away as train stations (a rail network can service far more stations as hyperloop for the same cost of building). Like the maglev train, it turns out that this is bad for the economic viability for building such lines. Apart from that, hyperloop has bad passenger comfort, it will be like traveling in a space rocket. People with medical problems can't use such a system.
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  2. Jet fuels can be made from algea. They are not "too expensive", the costs of flying is simply too cheap.
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  3. Just 1% of the surface area of all deserts would suffice to produce total world energy, and when solar thermal is used, it can produce also at night, so we would not have to use fossil fuels. Surround the solar plants with forests for protection against sandstorms, and use the excess heat of the solar plants for water desalination. There is your solution for climate change. REMARKS: 1. Electricity can easily be transported by HV DC lines. Losses are 3% per 1000 km. A large part of world population lives within 1000 - 2000 km of a desert. 2. Salt contamination. Instead of putting the brine (high salinity water) back in to sea (creating a dead zone) the brine can be left to evaporate completely in salt basins an then either harvested (if the salts have any value) or be burried under the ground. 3. Of course we would not produce all of elecricity/energy based on only one source (even when distributed around the globe) but mix in other renewables like wind, tidal, solar PV, bio fuels (from algea or seaweed or other organic biomasses). 4. Sea water can be pumped hundreds of kilometers into the deserts. On the high and low altitudes reservoirs can be created, so a pump-and-storage facility can be created to produce on-demand electricity without having to use fossil fuels for peak demand.
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  4. This plan is a bit dumb. You don't need to turn all the desert into forests, we better make a 20 - 200 km strip of forests at the borders around each desert, and install in this zone at suitable places (near oceans) solar thermal plants that desalinate water, and wind. That electricity is then exported mostly either by high voltage direct current lines or converted into hydrogen.
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  5. Some parts of the Sahara are hard deserts and due to the lack of rainfall, you can't terraform it. But other parts, like the Sahel region, can be recovered by planting trees to stop desertification. China did that in the Gobi desert. Afrika tries to do the same with the Great Green Wall of Afrika, a forest 15km wide and more then 4000km long from senegal to eritrea.
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