New answers tagged

7

It seems like you're worried about a problem that's not really a problem. Firstly, black holes take a long time to evaporate... over 575 trillion years at 6x1011kg (for gigawatt luminosity), over 15 million years at 1.8x1010kg (for terawatt luminosity) and over 2600 years at 1x1-9kg( for petawatt luminosity). Secondly, mass loss via Hawking radiation is slow ...


0

No, not at all. About 20% of the economy of an advanced country is the kind of thing that you might make with unlimited energy — food and manufactured goods. The rest is services. Energy can’t write a novel or make a movie or cut your hair or give you nursing care or advise you on how to lay out your garden or get you front-row seats at a concert.


-1

Ok worldbuilders, can we have a chat about METHANOL There's certainly methanol in seawater and this paper – Mincer, T. J., & Aicher, A. C. (2016). Methanol Production by a Broad Phylogenetic Array of Marine Phytoplankton. PLOS ONE, 11(3), e0150820. doi:10.1371/journal.pone.0150820 – says the following: Stan-dards were prepared using analytical grade ...


0

The New Age of Sails: Ships circumnavigated the globe using the power of the sea centuries before modern vessels, and they didn't even need hydrogen fuel. They used one of the oldest power sources on your list. They used sails. Today, modern ships are returning to their roots and developing sail technology to off-set the very power concerns you have. Deliver ...


-1

So your criteria are [1] autonomous, and [2] non-nuclear. I think there's a way to fulfill [1] if you compromise on [2] There are 3.3 micrograms of Uranium in a liter of seawater (http://large.stanford.edu/courses/2017/ph241/jones-j2/docs/epjn150059.pdf) Therefore there are 3.3 milligrams per cubic meter That's 0.0000033 kilograms per cubic meter Uranium ...


1

Unlimited Energy Doesn't Necessarily Mean Utopia From a theoretical standpoint, yes, you can take in sunlight and Hydrogen from the solar wind and combine the two into everything society needs. From a practical standpoint... Turning Hydrogen into Iron is going to require repeatedly fusing elements, then running the results through a separation process, since ...


2

6.1-megajoule, millimeter-wide, millisecond-long (6.1 gigawatt), 1-picometer wavelength, 300-exahertz laser pulse 1 picometer wavelength gives a photon energy of ~1.24MeV. That's comfortably into the hard x-ray, gamma ray regime. From the relevant NIST tables, you can see that this gets a mass attenuation coefficient of somewhere between 1.8 and 2cm2/g. ...


2

Now, can a person live off solely energy? (since elements can be converted to a metal of choice via energy). Trivially, yes. You can synthesise all the materials you need, so ultimately you can support life as you see fit. As MolbOrg pointed out though, the total amount of matter available from a sunlike star if you're merely converting its electromagnetic ...


0

It Could Easily Power Itself as Long as it is Staying Still The niche of Nuclear powered ships is long term deployment. But being deployed for a long time does not have to mean moving around a lot. LetEpsilonBeLessThanZero's answer sort of touches on this idea, but missing the mark on recognizing the usefulness of a stationary sub. The subs you are ...


0

For Endurance, Solar Might Work This is very dependent on water conditions, but light can penetrate dozens of feet of water. If you're at periscope depth, the hull is only a few feet below the waterline. If required, you could potentially extend some kind of semi-submerged or floating array - it would be easy to see in satellite imagery, but hard to pick up ...


6

Dyson Sphere, hm, no if your prerequisite is energy to matter conversion. It may depend on how much matter they need to satisfy their needs, how many of them there are, and all that. But using 100% of sun energy, in a 100% efficient way - they can make 4 million tons of matter per second. Or about 1.2e14 tons per year. This is a significant number, as mass ...


1

No, no non nuclear method can generate useful levels of power. Ocean currents require you to be affixed in a location and have extensive support technology requirements that weigh a lot. Unless you want your submarine affixed to the ground floating in a hoop, the submarine won't generate useful powers. Submarines are required to move around, often in ...


0

Yes. Seawater and sewage is a good source of chemical energy. Mohd Yasin, N. H., Ikegami, A., Wood, T. K., Yu, C.-P., Haruyama, T., Takriff, M. S., & Maeda, T. (2017). Oceans as bioenergy pools for methane production using activated methanogens in waste sewage sludge. Applied Energy, 202, 399–407. doi:10.1016/j.apenergy.2017.05. Pei, H., & Jiang, L. ...


5

What is a sub's role? Engineering anything involves maximizing strengths whilst minimizing weaknesses within a specific framework of constraints. Unfortunately, it seems the baby might have been lost with the bathwater when focusing specifically on size and power whilst ignoring (or at least understating) questions of mission-lifetime, surge-demand, and ...


0

If Evolution means Darwinian Natural Selection, then there is a problem: in order to get from point A (in phenotype space) to point B, there needs to be a path where each step is an improvement at the time the step is made. (It is OK if the improvement was a protection against a predator that subsequently went extinct, as it was an improvement at the time). ...


3

On the energy content of human waste The amount of energy remain in the gently used food varies widely based on the person and type of food. But, the highest figures I found during my searches was that about 25% of the original calories passed through undigested in the case of some kinds of nuts - the overall average being considerably lower in people with ...


17

Almost Certainly Not 6 MW is a lot of power, and all of the proposed mechanisms can only sip at available power. (Or wouldn't work at all.) Efficiency As with anything that moves through a medium, most efficiency gains are realized by aero or aqua-dynamics. So a knife-nosed submarine would see more efficient movement forwards, but would have enormous power ...


0

Although it WOULD take more eneegy than a surface or land vehicle, it should be noted that water is not always still. Take a look at the water during a storm, at how its waves travel and disperse Take a look at things like rivers and streams, and constant currents in the open waters One is predictable, one is not. One will fot well with your idea, meaning ...


1

The comments already explain that moving on the surface at similar speed will always require less energy. But if not so much extra energy is required and there are other problems to solve it might become plausible. A strong and constant stream is running along the coast. A couple of islands narrow and long break the stream in such a way that the current ...


0

Not Only Possible, but Been There Done That Got the Tee Shirt! Personal submarines are already a thing, and they come in an astounding array of sizes, configurations and utility platforms. There are already "partial submarine" underwater scooters, there are serious diving / exploration craft, there are road vehicle / open top submersible combine ...


5

There is no strict lower limit to energy use for propulsion: The slower your craft, the more energy efficient it is. If you want to make your sub super efficient, you just have to compromise on speed, and vice versa. Unfortunately, speed is essential for civilian uses: Passengers want to reach their destination yesterday, and they are generally willing to ...


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