by A. Cavallo
The report of the International Panel on Climate Change of UNO about the global warming has restarted the discussion about energy and the choices we have to make about it in the near future. In this issue of TDF we widely explain how the human origin of the current warming of the climate is dubious. What we know for sure is that least somewhere in the world the warming is real, although it is not even certain if it is truly global. But the problem of energy exists: the availability of oil is really shrinking, beyond the partially speculative price increases we are seeing in these days; the use of fossil fuels has anyway quite a few drawbacks. It is necessary, for sure, to revise the way we manage the production of power worldwide.
Of course, human civilization needs sources of energy and
in human history several have been adopted. In the ancient world the
main source of energy were human and animal muscles, or better the food
for humans and animals transformed into mechanical energy by muscles;
at the same time vegetal and animal originated fuels were used, like
wood and dry dung. If the supporters of downscaling are successful, or
if some other very silly choice is made, in the future we may go back
again to those forms of energy as our only resources. In the meanwhile
humankind has learned how to use at first flowing water and wind, then
fossil fuels, finally nuclear energy. The adoption of coal and
hydraulic power as main power sources allowed the industrial revolution
of XVIII and XIX century. Since then we have built up a global
civilization that needs an ever increasing flow of energy to survive.
As a mattter of fact we cannot hide to ourselves that the energy needs of humankind will keep growing. Even if it is true that the billion of people who live in the developed world can very well reduce their energy consumption without worsening their standards of life, we cannot tell all the others that they have no right to enjoy modern civilization. Especially two and a half billions of Chinese and Indians have eagerly set out on the road to development, with the prospect of multiplying more than three times the current use of energy products in the world. As I said on other occasions, we have to choose whether to make war for the known resources or try and find others.
The debate about global warming has little to do with the
energy problem itself. What we have to do is to find solutions in order
to improve the quality of life of the whole humankind. Filling the
world with power plants based on fossil fuels is wrong, if they damage
the environment, because it worsens the life of people, not for other
reasons. On the other side it is thoroughly evident that we shall
always need energy in significant amount and that, in order to improve
the life of the whole humankind, it will be necessary to keep
increasing the global power consumption, even if it is right that the
most developed countries work to avoid energy waste at home.
After saying that, we must dispassionately analyse which
energy sources shll be chosen for the near as well as the far future.
Renewable sources have precisely the advantage of being inexhaustible;
but we have to see how we can obtain the energy we need from such
sources. The only true primary known sources of energy are the Sun and
nuclear energy, including fission and fusion. We focus here on solar
power, leaving nuclear for another occasion.
Solar energy can be converted into the easiest form to handle, electric power, in two ways: directly by photovoltaic cells or indirectly through a thermodynamic cycle (heating up a fluid and making it expand in a turbine). In both cases, when exploiting it on the ground we face the great problem of its low density and limited availability, due to some factors with no exception, like the day/night cycle and seasons, besides the unpredictability of weather. The latter limitation can be overcome by placing the power stations in deserts, where at least the weather does not create problems. But in outer space limitations are much fewer: there are neither day/night cycles nor seasons, and there is no athmospheric absorption to reduce the already low density of power in arrive.
Nevertheless, compared with ground based solar power, the space based solution has two disaadvantages: it is necessary to build massive stations in space, which is very expensive today, and power must be sent to the Earth withoud solid connections, therefore again by electromagnetic radiation. In particular, microwaves should be adopted. Technical feasibility, according to those who tried to work about it, is not under discussion. It is only (not quite a little "only") a matter of engineering the solutions and financing the first experimental systems, and then the power stations proper. However, until now not even a demonstration prototype has been made.
The matter of fact is that the cost of space based solar power (SBSP) is today extraordinarily high, due not only to the high cost of solar systems themselves, which affects ground solutions as well, but above all the high cost of putting them into orbit. We face, in conclusion, the usual problem of the cost of lifting anything from the bottom of the gravitational well where we live to orbit or beyond. It is quite clear that solutions are always the same: reduce the cost to orbit or use non terrestrial materials. But to give a start to a new technology we need someone willing to pay the price.
The news of the last months is that the American
Department of Defence is taking into consideration the production
of power through space based solar systems for the use of its forces
deployed abroad. The National
Security Space Office published a paper saying that it is very
important for American military to have at their disposal sources of
energy which are not subject to risks for supply lines ad are available
in any part of the planet without limitation - a description that fits
perfectly with SBSP. At this address
the summary and the complete text of the paper are available.
As the NSSO reminds, NASA and DoE (Department of Energy) abandoned studies about SBSP some years ago for the reasons of cost we too explained above. But now, following the tempestuous increase of the price of oil and the great improvement of photovoltaic cells, according to the NSSO time has come to start again the activity with resolution. The proposed plan includes several demonstrators before reaching the construction of a 5-10 MW power station in geostationary orbit. Foreseen cost of the latter about 10 million dollars... Currently no direct financing by the Pentagon is foreseen, but at least they are beginning to apply pressure to the other government departments to obtain the restart of the development of this source of energy.
As Al Globus of Ad Astra points out in this other article, in order to make SBSP a significant power source, besides special applications among which I would include the military ones, it is necessary that the materials do not come from the Earth but from the Moon (and I would add from the asteroids). Once the virtuous circle of outer space colonization is activated, the development of a mining and manufacturing industry based on the Moon (and on nearby asteroids) would create the basis to fully resolve any energy problem on the Earth too... According to Globus the effort related to the search for inexhaustible and strategically secure sources of energy can give the needed impulse to start the colonization of the Moon.
The problem of the initial cost to make the "bootstrap"
of the industrialization of near space would not be so serious if
consideration was given, as Globus points out, to the fact that the US
are spending today fabulous amounts of money to maintain a huge
military apparatus and manage extremely expensive military initiatives
like the one in Iraq (about which the judgment must be very severe,
firstly because it was a war of aggression, immoral by itself,
furthermore based on false pretexts, finally managed in a foolish
besides criminal way) - while the development of a source of energy
like SBSP would give the national security of the US a much more
important and longer lasting contribution! As I pointed out in a
previous article, the overall actualized cost of the Apollo program,
from the first plan to the project closure after six lunar landings,
was equivalent to the cost of two years of war in Iraq. But the start
of the industrialization of space would create the conditions to solve
forever the problem of energy dependence from politically unstable
areas of the planet Earth, therefore its value would be immense even on
the strategic side.
This is a first concrete example of the use of space as a
resource and not as a field of pure research, and especially of the
advantages we can obtain by colonizing the near Earth space area,
including the Moon and the nearest asteroids - right those that
Hollywood and the media in general like to show as a possible menace!
Taking control of them for an industrial purpose could be useful also
to be ready in case some of them threaten to fall on our heads...
[003.AC.TDF.2007 - 04.12.2007]