Statement to the United States Congress Subcommittee on Space Science

The Technical Feasibility of Space Solar Power

Statement of Ralph H. Nansen, President Solar Space

Before the Subcommittee on Space and Aeronautics,
United States House of Representatives Committee on Science

September 7, 2000


The concept

of solar energy generated in space for our use on the earth was first proposed
by Dr. Peter Glaser in 1968 and has been studied extensively since then. The technology required for its development
is known and solar power satellites have the potential of delivering abundant,
low cost, nonpolluting electricity to all the nations of the earth. Their development has not proceeded because
of high initial development cost of a reusable heavy lift launch system and other
supporting space infrastructure. The
time is now right for the United States to lead the world in developing the
system. Fossil fuel costs are rising as
world demand is increasing while supplies are dwindling. In addition global warming highlights the
need to reduce carbon emissions in the atmosphere. The development of solar power satellites can solve these
problems and bring economic dominance to the nation that develops and owns the
system. The government’s role in this
program should be to provide leadership, seed money, and incentives for
commercial development. Specifically
the funding of a small scale Ground Test Program over a three year period at a
funding level of $30 million a year would demonstrate to the commercial
community the viability of the system. This along with tax and other incentives will bring about commercial
development and the resulting benefits to the United States and the other
peoples of the world.


The concept of solar
power satellites was conceived by Dr. Peter Glaser in 1968, but it was made possible
by the work of William Brown of Raytheon. The idea of generating electricity in space for use on the earth was
treated as an unrealistic dream when it was first presented. However, a few individuals in NASA thought
it ought to be investigated, so there were some low-level studies initiated to
look at feasibility. They concluded the
concept appeared to be technically feasible and the cost might be low enough to
be competitive if the cost of space transportation could be reduced

A study of Future Space
Transportation Systems conducted by Boeing for NASA concluded that
transportation costs could be lowered to very low levels with the right type of
reusable launch vehicles. This opened
the door to further studies of the system. When the OPEC oil embargo in 1973-74 triggered an energy crisis in the
United States an effort to develop alternative energy sources, including solar
power satellites, became a national priority.

In the late 1970’s a
broad-based Systems Definition Study was conducted under the joint auspices of
DOE/NASA. The System Definition prime
contractors were The Boeing Company and Rockwell International. I was the Program Manager for Boeing during
this period. The studies which involved
a large number of contractors and organizations concluded that solar power
satellites were technically feasible and had the potential of being
economically competitive. The problem
was the huge cost of development and deployment of the system before producing
significant revenues. There were also
uncertainties on the level of technology maturity, infrastructure development,
and cost estimates. As a result of
these concerns, coupled with the political opposition from the nuclear
industry, the government program was terminated in 1980.

Since 1980 organized
activity to study or develop solar power satellites has been limited. There was no US government sponsored work
until NASA initiated their „New Look Studies‰ in the mid 1990’s. Subsequently the Department of Energy
abstained from any involvement. However, during this time the Japanese government and industry became
interested in the concept. The Japanese
updated the reference system design developed in the System Definition Studies
in the late 1970’s, conducted some limited testing and proposed a low orbit 10
megawatt demonstration satellite. Their
effort has been curtailed by their economic problems. Interest by other nations has persisted, but only at low levels
of activity. The overwhelming initial
cost of development and deployment has remained the primary obstacle. Number one on the list of cost barriers is
the cost of space transportation. Solar
power satellites are only economically feasible if there is low cost space

In spite of the lack of
organized activity to develop solar power satellites much progress has been
made. Most of the development that has
occurred is in maturing technology of the subsystem elements and space
infrastructure. This includes solar cells, power processors, wireless power
transmission components, robotics, space habitation modules, reusable launch
vehicle technology, and computational capability.

A companion program to
solar power satellites was investigated which would utilize the same concept of
wireless power transmission to deliver electrical power from one location on
the earth to another several thousand miles away. This could be accomplished by transmitting radio frequency energy
in a wireless power transmission beam to a relay satellite in geosynchronous
orbit, which would reflect the energy back to a receiver on the earth called a
rectenna. This concept would allow
transmission of excess energy at one location on the earth to another that
needs the energy without the need to construct long distance power transmission
lines. This is an attractive
option. It does not require the
development of new space transportation systems as the relay satellite, though
large in diameter to reflect the wireless power transmission beam, can be light
in weight. The only active systems
required on the satellite are for pointing control and station keeping.

Over the last two
decades knowledge of the potential of solar power satellites to provide our
world with unlimited clean energy has drifted from the public conscience. Most people are unaware of the concept

This testimony is being
presented to provide a brief review of Solar Power Satellites, why they have
not been developed, why the United States should developed them, what the
situation is today, and of particular importance is the steps the United States
Government can do now to speed their development.

What are Solar Power

Solar power satellites
as envisioned are large-scale power plants based in space in geosynchronous
orbit. The satellites would be in the
sunlight for over 99% of the year. They
would only pass through the shadow of the earth for brief periods during the
spring and fall equinoxes. Electric
energy would be generated by vast arrays of solar cells converting sunlight to
electricity. The electricity would be
routed to a phased array transmitting antenna that would convert the
electricity into radio frequency energy and transmit the energy in a wireless
power transmission beam to an earth-based receiver. This receiver, called a rectenna, would convert the radio
frequency back into DC electricity. Power processors would then convert the DC electricity to AC power for
distribution on existing power grids.

The power output of
each satellite studied during the System Definition Studies was 5 gigawatts
(about equivalent to the output of Grand Coulee Dam). Smaller satellites are possible. However, smaller satellites still require large space transmitters which
result in increased cost of the electric power delivered to the earth. One gigawatt output is probably the smallest
practical size for geosynchronous orbit using radio frequency wireless power

Why have Solar Power Satellites
not yet been built?

The key issues that
prevented development centered around the size of the program, its cost, safety
of wireless energy transmission, and international implications. These issues were compounded by the lack of
the infrastructure required to support the program and insufficient validation
of cost competitiveness with other sources. Also, it is a high technology space program that is outside the
framework of the conservative electric utility industry.

Solar power satellites
are only cost effective if implemented on a large scale. Geo-synchronous orbit must be used in order
to maximize the sun exposure and maintain continuous energy availability. The transmitter size is dictated by the
distance from the earth and the frequency of the power beam. The earth based rectenna also must be large
to maximize capture of the beam energy. Given that the system must be implemented on a large scale, the cost of
space transportation and the required space based infrastructure becomes the
dominating development cost. Development cost of space transportation is driven by the need to
dramatically lower the cost of space launches which can only be reduced to low
enough levels by the use of fully reusable heavy lift launch vehicles which do
not exist today.

The existing space
transportation market has not been large enough to justify the huge development
cost of a reusable heavy lift launch vehicle system. However, solar power satellites would create a large enough
market if the perceived risk of their commercial viability is reduced to an
acceptable level for the commercial investment community. The commercial investment community has been
unwilling to invest in a long term, high cost project of this magnitude. The recent failure of the Iridium global
satellite communication system has underscored the potential risks with space based
commercial systems.

The concept of wireless
communications is highly accepted and used the world over. The concept of transmitting power is
not. The perception is that the power
cannot be transmitted safely to earth.

Why Should they be Developed in
the United States now?

Energy demand continues
to grow as our population expands. The
electronic age is totally reliant on electric power and is creating a new need
for electric power. Many areas of the nation are experiencing energy shortages
and significantly increased costs. United States electricity use is projected to increase by 32% in the
next twenty years while worldwide electric energy use will grow by 75% in the
same period. Worldwide oil production
is projected to peak in the 2010 to 2015 time period with a precipitous
decrease after that due to depletion of world reserves. Natural gas prices in the United States have
doubled in the last year as the demand has grown for gas fired electrical
generation plants.

Global warming and the
need for reduction of CO2 emissions calls for the replacement of fossil fuel
power plants with renewable nonpolluting energy sources. Even with increased use of today’s knowledge
of renewable energy sources carbon emissions are expected to rise 62% worldwide
by 2020. If we have any hope for a
reversal of global warming we must dramatically reduce our use of fossil fuels.

Solar power satellite
development would reduce and eventually eliminate United States dependence on
foreign oil imports. They would help
reduce the international trade imbalance. Electric energy from solar power satellites can be delivered to any
nation on the earth. The United States
could become a major energy exporter. The market for electric energy will be enormous. Most important of all is the fact that
whatever nation develops and controls the next major energy source will
dominate the economy of the world.

In addition there are
many potential spin-offs. These

  • Generation of
    space tourism. The need to develop low
    cost reusable space transports to deploy solar power satellites will open space
    to the vast economic potential of space tourism.

  • Utilize solar
    power to manufacture rocket fuel on orbit from water for manned planetary

  • Provide large
    quantities of electric power on orbit for military applications.

  • Provide large
    quantities of electric power to thrust vehicles into inter-planetary space.

  • Open large-scale
    commercial access to space. The
    potential of space industrial parks could become a reality.

  • Make the United
    States the preferred launch provider for the world.

The Situation Today

The situation is much
different now than it was in 1980 when the earlier studies were
terminated. In the ensuing years much
has changed. Other programs have
sponsored research and development of several of the enabling technologies and
much of the required infrastructure has been developed. Studies have continued in several countries
outside of the United States and some limited activity is sustained by
individuals and companies on their own funds within the United States.

The development of
terrestrial solar cells has caused the photovoltaic industry to grow from a
very small specialty group of companies manufacturing expensive solar cells in
laboratory quantities to an industry that is approaching maturity. Annual production is now well over a hundred
megawatts and growing rapidly. Production processes have become automated and the number of different
types of cells is greatly expanded. Thin film cells with efficiencies over 18% on metal film substrates and
with inherent resistance to space radiation degradation will soon be in
production. These cells will produce
1400 watts per kilogram of mass with a cost potential of 35 cents per watt. The
decreased weight and cost will significantly reduce satellite cost and weight
from earlier estimates.

Microwave oven
magnetrons, manufactured by the tens of millions, have been converted into
high-gain, phase-locked, amplifiers and shown they can be used to operate at
high efficiency and at low noise levels in a wireless energy transmitter. Their low unit output eliminates the need
for active cooling, further reducing system complexity.

Even though the Space
Shuttle has not achieved its original goal of low-cost space transportation, it
has proven the concept of reusability with aerodynamic reentry and
landing. It and the Russian Mir Space
Station are developing the knowledge base for manned operations in space. The International Space Station will greatly
increase this base and is one of the key space infrastructure elements needed to
develop solar power satellites.

As a result of all the
developments that have taken place over the years since the 1970s it is now
possible to consider another approach for solar power satellites. Most of the estimated development costs for
the 1980 DOE/NASA reference design are no longer applicable. Over two-thirds of the total estimate was
for infrastructure that is now being developed for other programs. Even though the low cost and large payload
capabilities necessary for space transportation of a space solar power system
have not yet evolved, there is progress being made through commercial launch
vehicles for communication satellites and the NASA/industry X33 program. One-third of the original 1980 cost estimates
was to develop and build the first full-sized 5,000 megawatts output
demonstration satellite. Based on the
survey of several large utilities made by Solar Space Industries in 1994, a
more realistic size for the first satellite is 1,000 to 2,000 megawatts
output. This is the nominal size power
plant a typical utility grid can handle without major problems. It also reduces the rectenna size of the
reference system and therefore dramatically increases the potential receiver
site locations.

With these
considerations in mind it is now possible to take a fresh look at how to go
about developing solar power satellites, lay out a development schedule, and
identify who should be involved and from where the necessary funds will come.

This program is
different from developing other potential energy sources. No research is required to develop the
energy source for solar power satellites. It already exists. The sun is a
full scale, stable, long-life fusion reactor, located at a safe distance. All that is required is to design and build
a conversion system that can operate in the benign environment of space. The basic technologies are all known and
proven. It is primarily an engineering
application task to integrate these technologies into a operational system
rather than a scientific invention/research task.

An inherent feature of
solar power satellites is their location in space outside the borders of any
individual nation with their energy delivered to the earth by way of some form
of wireless power transmission that must be compatible with other uses of the
radio frequency spectrum. They must
also be transported to space. Government involvement to coordinate international agreements covering
frequency assignments, satellite locations, space traffic control and many
other features of space operations is mandatory in order to prevent
international conflicts. Solar power
satellites will ultimately become part of the commercial electric utility
industry and as such, that industry could be expected to shoulder the majority
of the burden of development. However,
the utility industry is not the only one that will benefit from the development
of solar power satellites. All of the
people of the world will eventually be the benefactors, through reduced
atmospheric pollution and the availability of ample energy in the future. As a result it makes sense that the
development of solar power satellites be accomplished through a partnership of
industries and governments of all the nations that wish to participate.

What the Government Should do
NOW to Initiate the Development of Solar Power Satellites

In a partnership of US
government and industry it is vital that the leadership and responsibilities of
the various elements be clearly defined in order to prevent chaos. There are some logical parameters to outline
how this can be done. The first step is
to establish a lead nation. The United
States is the logical leader in this area because of the breadth of technology
infrastructure and capability that already exists, as well as the magnitude of
financial resources available in its industry and financial community.

The primary role of the
government in this partnership will be to provide leadership and seed money to
initiate the program, coordinate international agreements, support the
development of high technology multi-use infrastructure, and assume the risk of
buying the first operational satellite. The United States Department of Energy is the responsible government
agency in the USA. They need to form a
Solar Power Satellite Program Office to coordinate international cooperation
and to be the focal point for other participating US agencies such as NASA, the
Environmental Protection Agency, Federal Communications Commission, State
Department, Department of Defense and the Department of Commerce. NASA, because of its expertise in developing
space technology, will have the biggest role and is the appropriate agency to
support the development of the multi-use space technology and infrastructure.

The last element of the
government role should be the purchase of the first operational satellite. A government owned utility such as
Bonneville Power Administration is the logical buyer of the first unit. Bonneville with more than 20,000 megawatts
of generating capacity and an extensive distribution system is large enough to
absorb the power from a 1,000 to 2,000 megawatt power plant. In addition, there are sites within their
service area where the rectenna could be built. The cost will be repaid by the revenue generated by the
satellite. The main reason a government
utility should buy the first unit is so the government would accept the initial
financial risk.

The other half of the
partnership is industry. Industry can
provide most of the developmental funding and be responsible for the design and
development of the system. It is
essential that the satellites and the space transportation system be developed
in a commercial environment if they are to be viable commercial ventures.

The government needs to
take the initial steps that will make it possible for commercial development to
take place. Government agencies should
not attempt to design and develop a commercial system, rather their role should
be to create the opportunity and incentives to provide for commercial development. The following tasks should be initiated

1. Fund a Ground Test
Program to demonstrate the satellite functions of power generation, wireless
power transmission system, and integration of the energy into a utility grid on
the ground. The Ground Test Program could
also demonstrate the capability of the relay satellite power transmission by
simply introducing a reflector into the power transmission beam. Thus the same program can demonstrate both
concepts. The funding requirement for
this program is very modest. A
comprehensive Ground Test Program could be conducted for $30 million a year for
a period of three years. Much of it
could be obtained by focusing the funds that are currently being considered for
the Solar Power Satellite Program on the Ground Test Program. This program
would demonstrate to the commercial world the technical capability, efficiency,
and subsystem costs of the power generation and wireless power transmission
portion of the system. With this
demonstration in hand the commercial companies would have the evidence they
need to justify commercial investment in the operational system. A description of the proposed Ground Test
Program is attached as Appendix A to this statement.

2. Obtain frequency
allocation for worldwide wireless power transmission for operational satellite
systems. This is a crucial step needed
at this time as the communications industry continues to search for additional
frequencies. It is imperative that
wireless power transmission establish its own frequency base. This should include 2.45 and 5.8 gigahertz
as the absolute minimum.

3. Implement the
commercial space development tax incentives currently being considered in
Congress. The Zero Gravity, Zero Tax
bill is particularly important to commercial development of space.

4. Incorporate space
infrastructure development and tests for solar power satellites into the plans
for the International Space Station. Funding could be obtained by modifying the test and operational plans. It would give commercial purpose for the
International Space Station. A
candidate list of potential tests to support Solar Power Satellite development
and space infrastructure development is shown in the attached Appendix B.

5. Continue technology
development for reusable space transportation systems.

6. Consider the
implementation of loan guarantees for commercial development of reusable space
transportation systems and other required space infrastructure systems.

7. Commit to the
purchase of the first operational Solar Power Satellite after the successful
completion of the Ground Test Program.

Appendix A

Ground Test Program Description


Demonstrate the
complete function of solar power satellites as an electric power generating
system for the 21st Century and the function of an energy relay satellite. This would include verifying technology and
cost viability of the system elements associated with power generation,
transmission, power conversion, and integration into an electric utility
grid. It would provide the required
data to update the design of a full-scale solar power satellite system.

Give the electric power
industry confidence in the soundness of the concept.


The concept of the
Ground Test Program is to build a small scale solar cell array, (in the range
of 50 to 250 kilowatts peak output); couple it to a phased array wireless power
transmitter which would transmit the energy over a short distance (1 to 5
kilometers) to a receiving antenna (rectenna); that feeds the DC power output
through an inverter/power controller into a commercial AC utility power grid.
This is illustrated in the following figure.


Each element of the
system would be designed to incorporate several different technology approaches
to be tested in the complete end to end test installation. For example the array could be made up of
several 20 to 50 kilowatt sub-arrays of different types of cells, each with its
own wiring scheme and power controllers. The transmitting antenna could have several types of radio frequency
generators or have all of one type for one test and then be modified to another
type for the next test. Different
control circuitry could be tested to find the best approach for beam control. Various receiving antenna designs would be
tested with associated power controllers integrated into the operation to test
different designs for connecting into a commercial electrical grid.

The installation would
duplicate all aspects of the power generating systems for the Solar Power Satellite
concept, except for the space environment, and the range and size of the energy
beam. The other functions of the
satellite system have similar requirements to those associated with current
communication satellites, except for size and the requirement to be assembled
in space. These issues can be separated
from the power generation function and verified by testing done on the
International Space Station and Space Shuttle.

The concept of a relay
satellite would be tested by changing the pointing direction of the transmitter
and installing a radio frequency reflector that would reflect the transmitted
energy onto the receiver. The radio
frequency reflector acts in the same way as a mirror does for light.

Appendix B

International Space Station
testing to support development of Solar Power Satellites

The International
Space Station is one of the key infrastructure elements needed for the
development of solar power satellites. The basic technology for the power generation and transmission will be
developed and validated by a Ground Test Program, but this program does not
address the issues unique to the space environment. These can only be tested in space. The Space Station is ideally suit to this task. Solar Power Satellites is a commercial
program that will provide very large economic returns for the investment and by
using the Space Station as the in-space test base will give the Space Station a
commercial base to pay for its cost of operation.

A preliminary list of
the research and development tasks and tests required for the development of
solar power satellites, that could utilize the unique capabilities of the
International Space Station, is shown in the following:

1. Test
alternative structural concepts and assembly techniques for satellite structure.

2. Evaluate
capability of alternative robotic assemble concepts.

3. Test
radio-frequency generators and their characteristics when operating in the
space environment.

4. Assembly
techniques for the wireless power transmitter structure and subarrays.

5. Wireless
energy beam formation and steering in the space environment.

6. Wireless
power transmission in space from point to point (short range initially).

7. Wireless
power transmission from the space station to the earth using the power
capability of the space station. Evaluate
beam formation and steering. Determine
atmospheric effects and losses, including weather effects.

8. Evaluate
and test potential candidate solar cells for performance in the space

9. Test
candidate mounting and assembly techniques for solar cells.

10. Tests
of transmitting antenna rotary joint concepts and performance in the space

11. Test
ion thrusters and other electric thruster concepts for the attitude and station
keeping control system. Determine
characteristics and performance in the space environment and their
compatibility with the solar array.

Ralph H. Nansen
NW 98th St. Seattle,
WA 98117

President, Solar Space Industries
Phone:(206) 706-9811

Ralph Nansen is the founder and
president of Solar Space Industries. He has been recognized as one of the key
leaders in the world to develop, promote, and manage the Solar Power Satellite
program since 1973. He is the author of an advocacy book for the public titled SUN POWER: The Global Solution for the
Coming Energy Crisis, published by Ocean Press.

Mr. Nansen has been involved in space
engineering for over 40 years, primarily with The Boeing Company. He started as
a designer on the Bomarc rocket/ramjet-powered missile, and in 1961 was selected
to develop the initial configuration used by Boeing in their successful bid to
design and build the giant first stage of the Saturn V moon rocket. In 1962 he
became design manager of the Saturn S-1C fuel tanks, the first stage of the
rocket that sent the Apollo astronauts to the moon.

Mr. Nansen’s final assignment on the Saturn
program was as Saturn V Cost-Effectiveness Manager. After the moon landing he
moved into the position of Design Manager for the Boeing Space Shuttle
definition studies. In 1973 he was made manager of the Design-to-Cost

From 1975 to 1980, Mr. Nansen was
Boeing Solar Power Satellite Program Manager and gathered together a team of
engineers, scientists, and associate contractors to develop the overall concept
under the auspices of the Department of Energy and NASA.

By the mid-1970s, Mr. Nansen was well known
for his work in advanced space concepts and cost analysis. He was invited to
present numerous papers and participate in international conferences on future
space projects in Germany and Egypt. He was invited to China as a member of the
first Space Technology Exchange Mission in 1979. Mr. Nansen was asked to
testify before Congressional committees such as the Senate Space Subcommittee
in 1976 and the House Subcommittee on Space Science in 1978 in addition to
privately briefing many Congressmen. He published numerous articles on Solar
Power Satellites and represented Boeing at such major space events as the first
Space Shuttle launch in 1981 and the 19th Space Congress in Florida in 1982.

In 1981 and 1982 Mr. Nansen participated in
the creation of the space-based ballistic missile defense system that became
known as the Space Defense Initiative (SDI). In 1983 and 1984 he was a manager
on a classified military program. From 1985 to 1987 Mr. Nansen was responsible
for the design of a fully reusable horizontal take-off space transportation
system and the structural design of Boeing’s National Aerospace Plane concept.

Mr. Nansen retired from Boeing in 1987 to
cruise the oceans of the world in his sailing ketch FRAM. But in 1992, Mr.
Nansen felt that the need for a new energy source was becoming imperative. As a
result he elected to terminate his retirement and resume the effort to develop
Solar Power Satellites. He returned to the United States and formed Solar Space
Industries in 1993 and wrote the book SUN
POWER which was published in 1995.

Mr. Nansen received a BS in
Mechanical Engineering from Washington State University.