"Alan Erskine" wrote in message
ond.com...
On 11/07/2011 10:41 AM, Sylvia Else wrote:
The Australian Government has, for reasons that have much to do with
politics, and little to do with the environment, decided to throw $Au 10
billion into the bottomless pit that is renewable energy.

Lest it all get turned into yet more solar panels and windfarms, I
invite all comers to submit their plans for orbital power satellites. At
least then we might get some technological advance for our money, even
though I doubt we'd actually see any orbital power.

Sylvia.

How can a SSPS be more efficient than PV on roofs? Also, it will help the
environment - I'm studying sustainability at the moment for a future
career.


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.


PV isn't the only way of generating electricity. Queensland (an
Australian state) is going to get several 250mW solar thermal power
plants - small by coal standards, but it helps. ST (Solar Thermal) could
also be installed on factory and warehouse roofs for power production
(look up SEGS - Solar Electricity Generating System) for about half the
cost per kW of PV (solar cells); ST is just not as pretty as PV,
especially if the PV is BIPV (Building-Integrated Photo Voltaic).


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



Also, there is TDP (my favourite subject; that I first learned about on
one of the sci.space groups in 2003) that can economically turn
agriculture and forestry waste into liquid fuels for transport;


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

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???

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 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.



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.



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.



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