Re: Art, where's the buzz on nanotech saving America today?

Straydog wrote:


On Mon, 27 Mar 2006, rrc wrote:

BMJ wrote:


Afterwards, that is if there's a world in the 23rd century, we'll have
innovate in the solar realm that is if they're not suffering from
another "S&E shortage" during that time.


One of the present drawbacks with photovoltaics is the relatively low
conversion efficiency of modules. This means that a PV installation
will require significant areas of land. In addition, renewable systems
require a large initial capital expenditure when compared with existing
systems. (I investigated the economic optimization of hybrid renewable
systems for my Ph. D.)


That's why I'd placed the 23rd century as a caveat. Present day
photovoltaics are pretty dead end.


You guys are not reading the newspapers. I don't have it handy, but there were about two WSJ articles where out in california quite a few new homes have solar panels built in (they get a tax break, I think) as a supplement
in case they have brownouts or rolling blackouts and everyone is happy with the direction this is going in. Its got a long way to go but the technology is already here and been here for 1-2 decades.

I know what you're referring to as, if I remember correctly, it has the backing of the governor. What I meant was about how systems are designed and what the present technology is like.

PV modules can convert only a small fraction of the available insolation into electricity. One of the main limitations is the semiconductor materials that are used. Until something more efficient becomes available, there's little that can be done about it.

PV module capacities are, at the most, on the order of a few hundred peak watts. That means that if one were to use them to, say, power a house, they would need a large area of land to properly site and space them. Building them into houses restricts their usefulness as their orientations would be fixed. In order to better utilize the available insolation over the year, the elevation angle should change to follow the angle of the sun with respect to the horizon. In some cases, modules can be set up to follow the sun during the day using solar trackers, but that can make the installation more expensive.

A lot of systems are over-sized, so that means that a lot of the power they produce could be wasted after meeting the required load demand. Some of it can be stored, but that's limited by battery size as well as the charging current. (Avoiding gassing is important, particularly if one uses, say, lead-acid batteries.) Unless one has either an auxiliary load, which operates if the power is available, or it can be put into a utility grid (obtaining permission to do that can prove to be a regulatory headache), whatever's left is often dissipated.


It would have to be a collection of

lunar or orbital systems which then "microwaves" the solar radiation
back to the surface for power.


Now that is a bad idea. Mis-sim the microwaves and you'll be frying people. What a hijack target. Don't put all your eggs in one high-tech basket.

So the cycle I see is Alberta/Siberian/Kazakh oil from here till 2030.


You don't know what exploratory ocean drilling is going to come up with.

Offshore drilling is expensive and risky. A blowout can be very difficult to put out, as people found out in Mexico in 1979. Icebergs can be a hazard in some locations, such as off the shore of Newfoundland. Rigs can sink during storms, as Canadians found out when the "Ocean Ranger" went down with all hands in 1982. Even if oil or gas is found, the reserves need to be sufficiently large to make the hole financially worthwhile.


Modern Fischer-Tropsch coal->to->petroleum synfuels from 2025 till
2200.


Too early to predict.

Synthetic fuels from coal are a viable option in some locations, provided the seams are large enough to sustain production for several decades.



And then afterwards, a network of extraterrestrial solar stations

pooling energy for the surface along with limited fusion facilities.


.

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