Review: Criswell on Lunar Solar Power

How much sustainable energy is available for sustained global wealth? That was the question mild-mannered Houston physicist David Criswell began with in his arresting lecture February 17th, 2005 at Farmingdale State University on Long Island. 

The 20th century saw tremendous improvements in global wealth, with billions of people added to the world, and many of those billions living in a manner far beyond the means of previous generations. Nevertheless, billions still live in poverty, and one of the most important things they lack is access to energy. As Criswell put it, "the energy crisis for most people has been going on for hundreds of years"

To bring 6 billion people up to Western standards requires roughly a factor of 2.5 more energy than we use today. Bringing that level of wealth to all 10 billion people likely to be alive in 2100 means adding another 1.5-2 times what we use now. That means a total of close to 20,000 GW of electric energy, continually available to the world - 2 kW for each of 10 billion people.

20 electric TW is roughly the equivalent of 900 Mbboe/day ; that level will never be available through fossil fuels, with oil companies today struggling to supply 85 Mbboe/day.

Electric energy produces wealth: 1 kW through the year amounts to 8760 kwh, and generates $20,000 of economic activity. 2 kW per person, or 20 TWe total, would bring gross world product to close to $400 trillion/year, with world-wide individual incomes on the order of $30,000/yr.

Any nation that can bring this level of energy access to the world will have an immediate economic advantage. But how can it be done?

One solution is Lunar Solar Power.

The Moon has no weather, and constant uninterrupted sunlight. Solar panels deployed on the edges of the Moon, with power plots beaming energy towards Earth, could supply 20 TW of electric energy while using less than 1% of the Moon's surface - and since deployed on the edges, this would be unlikely to even be noticeable from Earth.

Energy beams from the Moon would be redirected by satellites in Earth orbit to ground receiving stations, which would in turn route the electric power directly into ground-side electric grids. This all sounds exotic, but as Criswell put it, the energy beaming is simply a form of radar, which we've been doing now for over half a century.

For example, Criswell showed the 6-storey radar station at Elgin Air Force Base, which has been beaming radar power nonstop, 24/7 for 36 years now. The beam there operates at about 20 times sunlight (25 kW rf/m^2), which is about half the transmission intensity that would be needed at the lunar stations to send to Earth.

Power beaming has been tested between distant points on Earth, for example in the 1975 Goldstone test, at 2.4 GHz over 1.6 km, with 85% efficiency. We have even had effective tests of Earth-Moon power beaming: the Arecibo radio telescope regularly beams radar at 20 W/m^2 through the atmosphere, to map the Moon.

The only outages the lunar solar power system would have are during full eclipses, 3 hours at most, for which we'd need some sort of temporary power storage or alternatives, roughly once a year.

The power bases on the Moon would be elliptical, roughly 100 km across, and about 600 km along the edges; Criswell displayed a simulated picture of a "Harvested moon" showing these as seen from Earth - about 2/10 % of lunar surface would be used, and this would be near invisible.

The most massive components needed are solar arrays, microwave generators similar to the magnetrons used in radars and microwave ovens, and reflectors to direct the power beams to Earth. The bulk of these main components would be manufactured out of lunar material, rather than shipped from Earth. Criswell estimates that for each 2 kW/person energy supply, 30 kg of lunar material is needed. That quantity of lunar material, delivering power over a 70 year lifetime, would replace the equivalent of 320 tonnes of oil!

The solar arrays would be deposited on lunar "glass" using large-area thin-film electronics - tests of this have already been done on Earth using simulated lunar materials and simluations of the lunar vacuum environment. Thin film materials should not be a problem; incoming meteors would erode the material at an average of 1 mm every million years.

There has already been some investment in the technologies needed to make this a reality - $2 billion has been spent on scientific work on lunar material, $50 M on various studies of space solar power in general, and some $2 M on lunar utilization - in addition to several million dollars worth of personal time and investment by Criswell and associates. With the changes at NASA there's a recent renewed interest in returning to the Moon and using lunar resources, which may lead to much more development in this area in the near future, whether or not it is specifically tied to the lunar solar power plan.

Criswell went into some comparisons to other energy sources - for the most part they can be classified as either inadequate (relative to the 20 TWe need) or non-renewable. There are also the issues of pollution and nuclear proliferation, and dependence on politically sensitive regions of the world. Fusion is not yet technically feasible, but has potential. Wind and solar on the ground could potentially scale up to meet world energy needs, but will likely remain too costly to be effective energy sources. For reference, Criswell stated total wind power resources amounted to about 300 TW mechanical around the world.

The advantages of the Moon:

Criswell estimated the life cycle costs for different energy sources to supply 1000 TWe-yr (50 years of a prosperous world to 2100, at 20 TWe):

Energy costs from the LSP system will be less than one tenth as expensive as they are now, and energy would decline to only a small portion of the economy. The LSP system would have huge growth potential at low marginal costs; energy payback for adding new components in the mature system would be as little as one month. Fewer grid connections would lead to high reliability. More extensive use of Moon resources (to manufacture the manufacturing plants, etc.) could lead to exponential growth of lunar systems.

The LSP system leads to huge quantities of power - commercial power independent of the biosphere. So we can start thinking about remediating Earth's natural systems. If we really still need fossil fuels (and this might make more sense than hydrogen) we could "recycle synthetic petroleum" using the electric power from the LSP system.

Advantages to the US, if it takes the lead on this:

The LSP system can lead to sustainable profits for any corporation that develops it - 1.5 T$/year at 1 cent/kwh. The lunar economy would grow to at least $3 trillion/year.

What next?
Demonstrations on Earth are possible in 1-4 years, at a cost of 60-120 M$. LSP operating components, lunar-specific component production would be the key there. In 6 years, for about 2 B$ we could start to build demonstration power plots in a simulated lunar environment, here on Earth. These would demonstrate sending commercial-level power to space and the lunar vicinity. The next step after that would be to actually return to moon and establish a demo base there. Key would be to make this not just a government venture, but enable private investment to commercialize LSP construction, and establishment of rectennas on earth.

About 7 years of the profits of the worlds 5 largest oil companies are all that is needed to establish a profitable lunar solar power system.

There followed a lively question and answer session; Criswell's most interesting point was economic: if energy can transition from being 10-12% of the US economy to just 1%, it could release enormous wealth. To set up the 30 kg/person of lunar material needed would, in Criswell's estimation, require about 100 to 1000 times less in machinery imported from Earth, or perhaps even better.

Further Reading on Criswell's ideas:
Solar Power via the Moon - The Industrial Physicist, Vol. 8, p. 12 (2002).
Lunar Solar Power System for Energy Prosperity within the 21st Century, World Energy Council, Houston, 1998.

Created: 2005-03-03 01:34:54 by Arthur Smith
Modified: 2005-03-03 01:35:53 by Arthur Smith