Moon Miners' Manifesto

#7 July 1987

POWERCO - The Lunar Power Company

What does power generation on the Moon have to do with software? We'll soon see. Perhaps the most commonly proposed source of power for an initial Lunar Base whose requirements are in the 100-1000 kilowatt range, is a form of fast compact nuclear reactor such as is being developed in the SP-100 Program for space applications. Systems considered are thermoelectric, in-core thermionic, and Brayton-alternator types. Rather than use precious water* as a coolant or thermal transfer medium, we could use "NaK", liquid sodium / potassium which is a good eutectic medium and can be wholly lunar-sourced.

* [Now that Lunar Prospector has since discovered water ice at both Lunar Poles in 1998, it would be legitimate to use some of it in closed coolant loops for this purpose. NaK, it seems, is nasty stuff, and we did not realize that at the time of writing. - PK]

The usual reason for proposing the nuclear option is the need to have steady power all month long. It is imagined by nuclear proponents that since the Sun shines on the Moon for 14.75 days at a time (dayspan) alternating with equal periods of darkness, a Lunar settlement that relied on solar power would have to power-down to an ultra-inactive state of torpor during the long nightspan.

Having grown up in Eisenhower's Atoms-for-Peace era, I was naturally ardently pro-nuclear in my youth. This frame of mind has long since been replaced by the opposing prejudice that the only good nuke is a dead nuke or no nuke at all. But however you feel about the question, please bear with me while we take a second look at the solar route.

The advantages touted for solar power on the Moon are not to be ignored. The collectors are easily made from lunar materials. Solar power is intrinsically modular. A solar plant can be added to, cloned in the next neighborhood, sized specially for industrial areas and so on. Solar power makes a good neighbor and generates no "Danger: Off Limits" signs. On the air less, cloudless Moon, the intensity of sunlight on the surface is steady and much greater than on Earth.

But the night! But the night! chant those easily discouraged through O'Neill on down. Yes, the night! Two considerations: energy storage and energy usage.

The very nature of living conditions on the Moon suggest an elegant answer to nightspan power generation. On the Moon, even with possible polar permashade deposits [since confirmed in 1998], water will be a premium, a resource dearly earned or made possible by costly imported hydrogen, a resource never to be squandered. Water will be as precious, as sacred to the "Lunans" as it was to the Fremen on Frank Herbert's Dune-world of Arrakis. We will want, nonetheless, not just enough to make the life and industrial cycles work, but a healthy reserve.

How do we bank this reserve? In the from of tanks of liquid hydrogen? In the form of idle ice in tunnels beneath the city? That's like putting money under the mattress. No, the water reserves can, and should, and must be put to work in two ways. First it will be a justifiable investment in public morale and in the psychological well-being of the inhabitants to allow for some open water in parks and / or parkways. Why not recirculating fountains with goldfish ponds? Why not a meandering trout and canoe stream? Beside renewing and uplifting the spirits, such open double-duty storage will be a strong symbol of security, a tongue stuck out at the parched surface of this new / old world.

But the second "interest-earning deposit" banking possibility for water is to tie it to the solar power cycle. During the long sun-rich energy-productive dayspan, the solar power plant(s), sized comfortably above expected dayspan power needs, is also put to work disassociating some of the water reserves into hydrogen and oxygen. This could be done by high temperature catalytic cracking, a much more efficient method than that of electrolysis. This may not even require additional power if the waste heat generated by the solar power production is sufficiently high in temperature to be put to work in this way. That will depend on how well the solar power system's design can be optimized to "bust" water as a design by-product.

Then comes the nightspan! The solar power system shuts down at sunset and adjacent to it, modular banks of hydrogen / oxygen powered fuel cells ( such as those designed by Westinghouse ) come to life, slowly recombining the hydrogen and oxygen into pure water to refresh the city's systems and generating considerable amounts of electricity in the process. The contribution to the water purification-recycling burden is a not-minor fringe benefit.

What are the advantages of this plan? It is clean, dependable, far less liable to shut down, so modular that maintenance on individual units will not noticeably interrupt the smooth flow of power. And above all, since a solar system can be interspersed throughout the city, it will be far less vulnerable to a breach whether by meteorite, accident, or willful sabotage. The high modularity of this "hydro-solar" ( solar / water cycling fuel cells ) system also means that design improvements and breakthroughs can easily be taken advantage of. One is not frozen into a premature technology. Finally, the modularity of the hydro-solar system means the city can grow smoothly and not in the spurts held hostage to construction of added large centralized nuclear systems.

But this is still hardware, right? Right! So where's the "software"? Well, our second consideration was to be nightspan energy usage. Not being an energy systems engineer, I do not presume to estimate how much power the hydro-solar plant would generate during nightspan as compared with dayspan. This ratio will surely improve with system design and sizing. But I think it safe to say and honest to advise that during the fortnight of darkness, power available will be somewhat less than that available during the fortnight of sunshine. There should be enough, however, to make it quite unnecessary for the settlement to "hibernate" provided a whole new philosophy or approach is taken to the design of production systems, operations, and enterprises.

On Earth, where energy supplies are taken for granted, energy eating production facilities function around the clock, even in some cases seven days a week. Now in any enterprise there are processes and tasks that use more energy and those that use less ( e.g. inspection, wrapping, book work, etc. ), and these are are usually done side by side by separate personnel. For the Moon, it will be important for every prospective new industry to totally redesign its manner of operation to sequentially separate, so far as possible ( and here goodwill and repeated reexamination and rethinking will be needed ) all its process elements into a higher energy-using portion that can be done during the dayspan half of the month and a lesser energy-using portion that can be saved for the nightspan period. This won't be easy, and for many industries and businesses, the division will be quite unequal in terms of man-hours involved. Once such a thorough and resourceful precipitation of heavy and light tasks is made and the light portion comes up short, it may serve the enterprise to consider if some of the operations normally done by suppliers or outside contractors, or perhaps even by entrepreneurs using one's by-products and waste materials could be incorporated to fill in the nightspan man-hours budget and keep everyone productive. This would be the preferred method of balancing the work load through the month. If an enterprise still comes up short on the light-task side of the equation, it could also explore diversification into an unrelated appropriately sized light business to be activated when work is needed to fill predawn dates.

Now in a city of any size, there is bound to be quite a variety of activities, some energy-heavy, others energy-light, all needed to make the economy purr. Before we go to the Moon, probable mix scenarios should be thoroughly investigated over and over for various stages in the city-bound settlement's growth, and productive operations and enterprise portfolios designed accordingly.

Such a system will look and work differently than our business-as-usual. And I predict one enormous fringe benefit: worker morale. For many people, employed by such task-separating firms, the ho-hum of work-a-day routine will get a twice monthly shot in the arm at sunrise and sunset as they switch tasks, jobs, and duties usually but probably not always, in the same job location. For example, a worker might cast iron on the sun-up dayspan dates and make art crafts from slag during the sun-down nightspan dates. Or edit by night and print by day. Or separate ores by night and refine them by day. Or make tiles by day and lay them by night. The possible combinations are endless and refreshing.

This system, tailored to a mode of power generation which does not ignore lunar rhythms but harmonizes with them, will make its mark in lunar culture and civilization, a mark that will be distinctive and enviable. But to prepare for it, a lot of SOFTWARE homework can and must be done now.

Contents of this issue of Moon Miners' Manifesto