I'm quite confident that solar power will be the single largest source of electrical energy for humanity in the future. It will be combined with other things, of course, such as hydro power, geothermal, and I actually think nuclear is not a terrible option, so long as you're not located in a place that's susceptible to natural disasters. That, also I think, defies common sense. So long as there are not huge earthquakes or weather systems that have names coming at you, then I think nuclear can be a sensible option. There are much safer and better ways of generating nuclear energy - I'm talking fission here - than existed in the past when nuclear reactors first came out. At some point in the future it would be nice to make fusion work, of course. That'd be quite good, but in the mean time I think indirect fusion, being solar power, is a good thing to do. That's what Solar City is doing, it's really trying to improve the economics of solar power, and they're doing a great job. I don't run the company, so the credit really goes to the two key guys who run that company. They're doing a great job of really accelerating the good option of solar power in the United States, and hopefully they'll come to the UK as well.
A well made, high pressure Helium, Stirling engine is a good choice for the application...
Quote from: John Alan on 12/09/2017 02:50 pmA well made, high pressure Helium, Stirling engine is a good choice for the application...I get the impression that SpaceX has a bit of a downer on high pressure Helium!
In order to make large quantities of propellant to meet the planned ISRU they need a settlement site with a lot of available water as well as a lot of power. Water to cool a reactor shouldn’t be an issue since they need it anyway prepped to feed into the ISRU plant. Whether it’s pure or like permafrost that’s what they have to design the process around, so they have some incentive to pick a site where it’s easier.
There are a lot of Small Modular Reactor designs in development that might be suitable too.
Not that the little 10k plants won’t be useful too.
I’d think with large amounts of Methane and LOX stored they’d have some use for Methane Fuel Cells. The waste heat would come in handy and the fairly pure CO2 could feed back into ISRU. Reactors would be better for cranking out LOX and Methane 24/7 than Solar.
Are they making it for anyone or any planned mission? The concept was pushed 10-15 years ago, but not sure anyone stepped up with the killer app or claimed it as a solution to their problem.
I talked with a SpaceX representative a few weeks ago about this given that I am a nuclear engineer.They have essentially no realistic concept of how to refuel on Mars.
Looking at other physically and economically impossible concepts like the hyper-loop and BRF Earth to Earth, I have no doubt that they just dont care.
Musk transferred to the University of Pennsylvania, where in May 1997 he received a Bachelor of Science degree in physics from its College of Arts and Sciences, and a Bachelor of Science degree in economics from its Wharton School of Business
Edit: I also asked them about a CO rocket engine, given that it could be extracted easily from the air without water mining, I was given the answer that this was rejected by Elon's trade studies. So yeah, the god doesnt like it, so it wont be done.
If you want to use methlox as your back-up/emergency power source, just install gas turbines. They are compact for power delivered, low maintenance in long idle condition, and can quickly start and pick up load.Discussion of nuclear is base load related... this is the long pole for expanding beyond the outpost stage on Mars or the Moon. Wonder if the Moon could be a 'proving ground' for 10KW Kilopower or space versions of naval nuclear reactors. A research-sized reactor modeled after that on the Navy's NR-1 deep submersible (MW scale) could be developed quickly by the USG...
The question should really be: What can Spacex do without and still achieve its goal?
Is nuclear really needed if you have a hydrogen/oxygen back up system? The big fusion reactor in the sky is so reliable...
What is the overall efficiency of a reversible hydrogen/oxygen electrolysis/fuel cell cycle? Taking into account that heat losses for a Martian colony are part of the system and that since heating will be maximum at night, when there is no sun, but when electrical demand should be low, there is excellent correlation with the heat loss from the fuel cell system?
Quote from: lamontagne on 12/10/2017 01:41 pmIs nuclear really needed if you have a hydrogen/oxygen back up system? The big fusion reactor in the sky is so reliable...Not when it's blanketed by a dust storm that cuts off 75% of your daytime sunlight and lasts for months, which can, and does happen, on Mars. IOW to handle such an event you'd need 4x to maybe 5x the baseline load to maintain power levels. That ignores how you're going to grow food in months long twilight as well, as artificial light multiples power needs about 6x IIRC.Quote from: lamontagneWhat is the overall efficiency of a reversible hydrogen/oxygen electrolysis/fuel cell cycle? Taking into account that heat losses for a Martian colony are part of the system and that since heating will be maximum at night, when there is no sun, but when electrical demand should be low, there is excellent correlation with the heat loss from the fuel cell system?Poor, if you have to liquefy or pressurize the H2, which you do if you want to store reasonable amounts. Basically LH2 or GH2 uses 3-4x the energy used to make it, and by extension 3-4x the energy you can recover from it. When you factor that energy into the process it makes a fairly poor way to move energy, let alone store and release it cyclically.
The best way to store energy on Mars is to make methane and oxygen, since they will need large quantities of that for rocket fuel and oxygen to breath. Eventually other industrial processes that use a lot of energy, make more of those products when excess energy is available. So if you have a continuous nuclear source plus variable solar, increase fuel production when the sun shines. Batteries will help, building up a stock of energy intensive essential commodities is better from an efficiency standpoint.