On 14/07/2011 10:23 AM, Jonathan wrote:



Efficiency isn't the key issue. Terrestrial solar has many limits on
it's usefulness. From the intermittantcy of day/night, to the storage
problem, clouds, rain and especially far from the equator.
But the glaring weakness of terrestrial solar, as well as most
green forms of energy is they can't ...add...to the baseload grid, only
reduce demand here and there. SSP can be directly plugged into a
large grid as if it were a conventional power plant.

SSP will have many market niches all to itself, so they can charge
what they need to if the choice is no electricity.



I would think Australia is far more favorable place for terrestrial solar
than most other places on Earth.


Are you sure we want to start burning food and forests for energy?
What are the longer term implications?

Look up "Short Rotation Coppice". Look up "Terra Preta" (a soil
improvement method). We don't burn either current forests or food
itself, just the residues from food and also specially-grown 'forests'.





Name one power source, of any type, that can provide baseload
power 24/7, rain or shine, to any point on Earth? And doesn't
require a constant train of expensive oil/gas/uranium/biomass
etc etc to pay for year after year???

There isn't one fossil fuel that does all that right now, not
efficiently - in most areas of the world, biomass power production is
ideal - it can use crop wastes - Australia could do away with all our
fossil fuels four times over just be harnessing our crop residues. Even
in the far Northern hemisphere, people use peat for fuel - even
powerstations run on the stuff. Then there's geothermal, solar for
electricity (both peak-load PV and base-load ST), wind (not my personal
favourite - I think wind turbines are just as ugly as high-voltage power
stanchons) etc.

Remember, most people don't, and won't live in polar or desert areas -
either too damn cold or too damn hot for the vast majority of people.
That means temperate and tropical areas - lots of biomass there.


Once a SSP power satellite goes online, it doesn't need to buy
even a single barrel of oil from that day forward.
The price of sunlight will never change, never be disrupted
by wars or politics. The satellite hardly has any moving parts.

And the PV wears out - good for maybe 10-15 years at the outside. Then
what? Re-skin the satellites? That's a cost and it will have to be
amortised.

Nothing is free. We live in a market-driven society that demands a
profit be made.



And the primary costs of SSP, launch and technology costs
should do what in the future? Only go down, especially with
technology. Maybe even with launch costs soon, the commercial
launch industry seems to be moving ahead pretty fast.


Costs of all technologies is going down. That includes Terrestrial
solar (PV and ST - solar thermal); biomass is also dropping, faster than
the price of fossil-derived energy is increasing. Transport costs will
always be higher for an orbital installation. Imagine having to
transport all your equipment and materials from one location to another
by using an aircraft - that would be far more expensive than using trucks.

Labour and assembly will also be more expensive for anything in space.
If automated systems are used for assembly, they will also have to be
developed. There's another cost.






gas for heating/electricity production and carbon-rich solids (commonly
known as 'bio-char') for soil improvement. A TDP plant can pay for itself
in less than three years - with just the sale of oil at $60/bbl - petrol
(gasoline to Americans) would cost about $0.80 per litre compared to the
current price of $1.30ish.

Now, what's the payback period for an SSPS and how many do we need


Space Energy inc says it should take about five years for construction,
about the same time for a conventional nuclear or coal plant.

Five years from the _start_ of construction! They have no chance of
getting that far. Terrestrial PV grew by over 53% last year alone over
the previous year and it's growing faster each year with no sign of
slowing down. No transport or installation problems for that either.




How do we economically get the power down to the users on Earth?


It's the initial costs that are the problem, once operating the ongoing
costs are small.



What are the environmental risks of getting the power down to the users on
Earth?


The beam at its strongest point is less than direct sunlight, you can plant
crops under a rectenna. Microwaves have been around some 50 years
and is a well known technology. Maybe the strongest reason for SSP
is the effect it could have on rural third world poverty, disease and
hunger.

Microwaves are also bloody dangerous. Stay out in direct sunlight for
any length of time - you'll still get cooked; and that's only for 12ish
hours a day - try 24 hours a day.

As for what you say about rectennas, you can also use the crops that are
_already_ growing there for fuel. Not the crop itself, but the residue
(straw etc). In Queensland (north-eastern state of Australia), there
are several power stations that use bagasse as fuel - it's the residue
left after the sugar is removed from the cane.

MSW (Municipal solid Waste - rubbish or trash) is also a source of fuel
- a city like Melbourne (4 million) could generate over 13,000 bbls of
oil a day from that. Then there's the solid content of sewage to be
added to that total - another million tonnes of biomass a day. None of
it is currently being used. That's about 10% of Melbourne's total crude
oil consumption right there, and we still haven't got to the farms yet.

The same technology I've mentioned before, TDP, can help developing and
impoverished nations as well. Where do you think they get their current
supplies of fuel for electricity generation and transport? It's mostly
oil and coal - fossil fuels - and we don't need those.


Someone a couple of months ago suggested using laser-powered LV's for
payload to LEO - fine, until you try to find the electricity to power
those HUGE lasers! Those three questions above have never been answered
adequately; please try.

Here's a nice 15 minute presentation or sales pitch by
Space Energy Inc.
http://spaceenergy.com/i/flash/ted_presentation



We don't need SSPS even if they were practical, which they are not. We
have plenty of resources here on Earth that we are simply not using
efficiently or effectively.

http://spaceenergy.com is a good-looking website, but it's all 'spin'
and no reality. They simply can't compete with Terrestrially produced
energy.

Solve the problem of transport costs and the problem of assembly and
then we can talk about SSPS.