SPS versus other energy sources

> Hello, Victoria,
>
> While Charles raises an important issue regarding frequencies
> assignment, I suspect we will find that the biggest obstacle to SPS is
> the successful introduction of solar power "shingles" at a price that
> many homeowners can afford. These have been on the market for about a
> year.
>

Cost is a completely different issue than Victoria was discussing.
So I have changed the name of this thread accordingly.

I can summarize it like this:

SPS will never compete on price with fossil fuels.

SPS will never compete on price with nuclear power.

1) SPS versus fossil fuels:

Disadvantages / Risks of fossil fuels:
a) big balance of trade defecit to import them
b) reliance on unstable political region of the world
c) hence high military cost to maintain peace on oil producing regions
and defend the energy assetts
d) greenhouse gases and global warming.

SPS could be come viable if the energy consuming nations change their
policies as a result of one or more of the four factors listed above.

2) SPS versus nuclear power.

Disadvantages / Risks of nuclear power:

a) security risk of transporting and storing fissile materials, risk of
terrorist hjaking
b) risk of leakage of radioactive materials from reactors
c) risk of reactor meltdown / explosion (e.g. Chernobyl)
d) security risk of transporting and storing radioactive, risk of
terrorist hjaking
e) risk of leakage of radioactive waste into the biosphere.

SPS could be come viable if the energy consuming nations change their
policies as a result of one or more of the four factors listed above.
Fox example, nuclear power might be made relatively safe in developed
countries, but in undeveloped countries we would see a much higher risk
of accidents, and security problems.

For SPS to become viable, they will have to stop using both nuclear
power and fossil fuels.

After that, we then enter a debate about SPS versus terrestrial
renewable sources (wind, terrestrial solar, etc).

My summary is as follows.

Only one source of terrestrial renewable energy has enough capacity to
supply the world's energy needs, and that is terrestrial solar. The
other renewable sources simply do not have enough capacity.

There are many pros and cons, I can actually imagine a mix of
terrestrial and space solar power, they can service different types of
markets. Here are some interesting numbers which William Mook posted
to Usenet in July 2000:

>
> At the latitudes of North America the Sun during high noon at summer
> radiates about 600 watts per square meter incident radiation normal to
> a surface oriented to the sun. In space there is about 1,370 watts per
> square meter. So, more than half is lost. The space value varies plus
> or minus 15 watts per square meter primarily in the UV region due to
> changes on the surface of the Sun.
>
> Of course in winter months and at sunrise and sunset more energy is
> absorbed by the atmosphere, reducing the amount of power available per
> unit area by half again as much. (only 250 watts/square meter getting
> through!)
>
> And at night and on overcast days, things are worse yet.
>
> In most parts of the US there are between 1500 and 2000 hours of
> sunlight a year. There are 8766 hours in a year. So, about 5/6 to 4/5
> of the time the sun is unsuable. Then add the atmospheric losses and
> you find that 19/24 to 9/10 of the sunlight available per unit area is
> actually available on the Earth's surface.
>
> Tracking the sun in space is much easier than tracking the sun on the
> ground. So, on the ground you don't do that. This limits your
> conversion efficiency so your collector area increases for a given
> pwoer output by an order of 3 or 4. Also, ground based collectors must
> withstand gravity and weather. This triples costs again! So, overall
> a square meter in space can be equivalent to 288 square meters on the
> ground worst case, or 30 square meters best case.
>
> Then, you've got the added inefficiencies and costs of energy storage.
> To take energy and make fuel is not 100% efficient. And to take fuel
> and make energy is not 100% efficient. Furthermore, the equipment to
> do this conversion and storage is not free. Finally, the conversion
> equipment must be sized for peak solar output, so is not as economic as
> it might otherwise be. Assuming 30% efficiencies for each step and a
> doubling again of the capital costs to make fuels of solar power, we
> have another 28.89 fold increase (1/.3 x 1/.3 x 2) meaning solar based
> power requires 832 times the cost on Earth for collector, and energy
> management than an equivalent power in space.

We also need to consider the environmental impact of popular power
storage systems on which terrestrial solar power systems completely
depend, it is actually a very high price. Most commercial batteries,
e.g. NiCd and Lead-Acid, contain highly toxic materials. This
represents a massive toxic waste problem, on the same scale of dealing
with nuclear waste.

However, the numbers above are not complete. They ignore two more
things: 1) the transmission losses of SPS and 2) launch costs for SPS

Here is a nice summary of the SPS losses presented by Tom Musgave to
this SSI list in June 2001:

DC to RF 0.85
Antenna 0.98
Atmosphere 0.98
Energy Collection 0.88
RF to DC 0.89
DC to RF 0.85
Antenna 0.98
Atmosphere 0.98
Energy Collection 0.88
RF to DC 0.89
Grid .97

=.97*.85*.98*.98*.88*.89*.85*.98*.98*.88*.89*.97
=.385 = 38.5%

Bottom line then is as follows:

Take the ratio of 832 to 1, multiply by 38.5 %, we get:

Space solar power has a performance per square meter advantage of 290 to
one over terrestrial solar power, if we ignore launch costs.

Colin continued:
> By themselves, they don't really compete yet, the market is not that
> big. It is the trend that I expect will scare off investment in SPS.
>

Yes Colin, but you have missed the reason. Neither terrestrial solar
power (e.g. shingles) nor SPS can compete with fossil fuels on
price. About ~80% (?) of US energy is presently supplied by fossil
fuels. Terrestrial solar power will never compete with that, neither
will SPS.

If fossil fuel usage is stopped, then we have a different debate.

> Why would anybody put up the huge $$$ for SPS when windpower is now
> financially competitive with nuclear?
>

On the one hand, SPS will never compete with land-based windpower on
price.

On the other hand, land-based windpower does not have the capacity to
supply the world's energy needs.

Ocean based windpower is one possibility, but that is dominated by the
high cost of long distance power transmission, in which case SPS is
highly competititve.

>
> What will be the impact on power production when fuel cells finally
> commercialize at the home scale?
>

Fuel cells are irrelevant, they are simply another way of processing
fossil fuels, with all the same problems, advantages and disadvatanges.

> When I can spend a few hundred dollars a year to add incremental arrays
> to my house, or spend ten thousand to pave the whole rooftop with solar
> power shingles, why would I support SPS?
>

Excellent question.

Some reasons were given above, e.g. SPS gives 24/7 power with no
expensive
power storage, and one square metere of SPS collector is worth 290
square metres of terrestrial collector (if we ignore launch costs).

>
> Yes, SPS might help the aluminum smelter down the highway, but that's
> his problem. I've got mine.

Your personal problems are not the driver. The driver is global
macroeconomics.

To extend your example:

You need the Aluminum from the smelter, you are buying their products.
And billions of people around the world need the Aluminum also.

>
> Successful, economically competitive ground-based solar power, wind
> power, fuel cells and other alternative energy sources will continue to
> seriously undermine SPS venture capital for at least a generation unless
> we get REALLY cheap access to space--mature space elevator cheap!
>

Fuel cells are irrelevant, they are just another way of processing
fossil fuels.

The terrestrial versus space solar power debate is the most relevant.
We should certainly discuss this some more.

But keep in mind that neither of them will compete with nuclear and
fossil fuels.