Environment Thursday, March 3, 2005. Post by apsmith
We’ve covered Criswell’s Lunar Solar Power idea before here; he’s refined his arguments since I last heard him speak on this, and the presentation is now very persuasive. I also had the opportunity of sharing a couple of meals with him (and others), where we could discuss things a bit more in depth. He’s dedicated an awful lot of his time to this for some 20 years, with very little outside support; the institute that he runs funds university research on a variety of space system topics, but it’s not specifically funded to develop the lunar solar power system, so it’s still something he has to do in his spare time.
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
; that level will never be available
through fossil fuels, with oil companies today struggling to supply
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
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
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
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 $3 trillion/year.
Demonstrations on Earth are possible in 1-4 years, at a cost of 60-120 M$.
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:
Power via the Moon – The Industrial Physicist, Vol. 8, p. 12 (2002).
Solar Power System for Energy Prosperity within the 21st Century,
World Energy Council, Houston, 1998.
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