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03 July 2018
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When "We" Go to Mars

Whomever "we" turn out to be, we will probably want to get home to earth. To do that, rocket fuel is necessary, and the cost of shipping it from earth is prohibitive. Making it on Mars is possible, since all the raw materials are there—carbon, nitrogen, oxygen, hydrogen—either in the air or in the ground. Of course, energy will be needed to extract and combine the ingredients, and that energy can come from solar power.

I was thinking about this a few months ago, and I mentioned the possibility to one of our people, academically a chemical engineer, but one who has turned his life around and become involved in the art of music. He agreed that with energy and raw materials, it should be possible. Later I found out that NASA had had thought of it first.

You might wonder why I was thinking about this. It's because I've become a solar geek, and the more I think about solar power, the more possibilities I see. Others are thinking in more detail: The careful reader will note the date on this blog and the date on this reference and wonder how it is possible I mentioned the real possibility of making ammonia, a high-energy-content fuel right here on earth* from sunlight when the article was written later than the blog. It's because I've been a dilettante, that's why, and just got around to finishing this blog today after starting it weeks ago. But the article by Robert F. Service — Ammonia—a renewable fuel made from sun, air, and water—could power the globe without carbon — is a must-read printed in a reputable journal.

Why Stop With Ammonia, or Rocket Fuel?

I'm a solar geek because solar power has turned my energy-using life around. I've had it at home for years, and just installed it at my place of striving. I'm perpetually bemused by the fact that it's FREE, a word and concept which I hold sacred! My personal electric bills have nearly vanished for part of the year. Due to the magic of (possibly) ill-considered laws, we are additionally being paid for something called SRECs which we get when the sun is shining via some mysterious exchange that turns them into a bankable check. The price of solar panel installations has been declining and appears set to continue on that course.

What happens when solar power is so cheap and plentiful that we are already producing an excess of energy? Not just a local excess, as I do on clement spring days, but a statewide or even global excess, such as occasionally happens in California when the whole state has too much electricity. Do we use it to pump water back from the Colorado River into Lake Meade? (Yes, if that proposed project is approved.) Do we use it to charge lithium batteries to provide power at night? (Mostly no; lithium is too expensive to make utility-scale storage practical.)

Or is it? I remembered the Rick Brant Sea Gold book of my youth, which dealt with extracting gold from seawater. I seem to have had a long relationship with FREE—that book was published, I just found out, in 1947. Back then, I'm sure they were planning to use atomic energy. That hasn't worked out as well as the optimists of the time hoped, but the sun itself is powered by atomic energy, so I'll declare the Rick Brant book to have been prophetic. And surely lithium, presumably as lithium chloride or other soluble salt, is far more plentiful in seawater than is gold!

The Grand Solar Plan

Q: OK, solar geek, why don't we already use solar power to "mine" lithium from seawater and make ammonia from air?

A: Because there are more efficient ways of accomplishing both. Lithium is highly concentrated in some areas (as brine), and easier to obtain there. The Haber-Bosch process creates ammonia more efficiently than atmospheric synthesis. At least it does right now. What happens as solar power gets cheaper or even, in a sense, FREE? Efficiency suddenly doesn't matter. Put a floating island of solar cells out in the ocean, have the island swim to shore whenever the lithium bin is full. It's a "virtuous cycle." As the price of energy decreases, the energy needed to create ammonia, rocket fuel, even food(!) from the atmosphere and ocean becomes lower than other raw materials and inputs to production.

When can we count on this happening? I'm a solar geek, not a prophet! But I'm thinking ammonia and rocket fuel in years, and maybe swimming islands with lithium bins in a decade or so. I love it when the doomsayers and pessimists are wrong.


* Well, Australia anyway.


 
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A mystical seal on a thoroughly motheaten T-shirt. But oh how striking it would be if I could still wear it.


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