We have a so-called 90 day supply of oil, but no reserve capacity for electricity on our major grids? I remember the day the entire Pacific Inter-tie grid went down from a damned squirrel shorting out one substation here in Hillsboro Oregon. They fixed that problem AFTER all the nonsensical worries about Y2K. Yeah, the grid was good to survive rolling cascades of overloads and outages in case of plant failures or long line downage.

Lord help us if Al-Qaeda decide to attack the grid with more squirrels. They might even upgrade to explosives.

Roll it up in a plan for Homeland Security, they get a budget slice like the DOE and have some concrete examples to point at.

Build the microwave receivers on the Nevada Test Site where the land is extremely polluted and cheap. Underneath put the Thorium reactors. Below the surface is the geothermal and hot rock stations for more power. Sprinkle the entire complex in solar panels to justify the costs and increase efficiencies. There’s a thousand square miles of desert there for the use

Power the robots to scrape the ground clean and put the waste and fallout into the Thorium reactor coolant and burn it up.
Power a 10 mile long rail gun and jettison the remaining nuclear vitrified ashes to ESCAPE orbit. Like 90 degrees to the ecliptic shot that never comes back. Use Magnesium Boron superconductors for the coils and contribute the shot energy onward to the grid.

The ground there is a total waste, and will get cleaned up. Nobody wants area 1-50, but they like to watch area 51 for space aliens. :}

It is possible to manufacture laser diodes with high efficiency like RAM chips on 8-10 ” wafers. IBM pioneered this technology back in 2000 or so. Billions of laser diodes possible with high yield and low cost, you betcha. Using semiconductor layering technologies and electron beam technologies, we can make lasers in several spectrums using the same substrate technologies.
Your ordinary DVD-ROM laser can be focused to light matches on fire. Can you imagine a cluster of 10000 on a wafer 10 mm and have been made to a spectrum mostly transparent to the atmosphere?

Like the gentleman in Iraq said, it’s a matter of willingness to pay for the energy. The US military is being shafted on a huge scale to get the oil they need at the right place and time.

It’s a matter on willingness, fear of pain of reduce supply and pretty much nothing gets done until there is a sufficient amount of overkill pain.

Wireless technology literally surrounds us with information, and the concept of the antenna has a crucial role to play. By converting free-space electromagnetic fields into guided waves, or vice versa, antennas act as either receivers or transmitters. The wavelength at which antennas operate is intrinsically related to their size and shape: for a simple antenna, the height required is approximately one quarter of the wavelength.

For an antenna to operate in the optical regime, its dimensions must be on the 100-nm scale. This has now been achieved by scientists in Spain and The Netherlands.

Starting with the flat end of a single-mode optical fibre, Tim Taminiau and colleagues create a sharp glass tip by so-called heat-pulling — applying tension to hot, soft glass. This tip is coated with a 150-nm-thick layer of aluminium and is then shaped by bombarding it with high-velocity ions. The result is a nano-antenna that is just 50 nm in diameter and has a height of between 30 and 140 nm. By positioning it on the edge of an aperture into the optical fibre, the local field effectively drives the antenna, replacing the transmission lines in the radio-wave equivalent. Simulations of the fields around the structure show that it behaves in the same way as a standard radio-frequency monopole antenna, enhancing the localized field near the apex at a resonant wavelength dependent on the height: a 75-nm tall antenna is resonant with green light with a wavelength of 514 nm. The device could also act as a receiver when driven by far-field illumination.

To demonstrate the potential of their antenna, the team have used it to perform near-field scanning optical microscopy on fluorescent molecules suspended in a polymer film. Laser light at 514 nm is passed along the optical fibre to excite molecules and the fluorescence is collected in the same way. The sample is scanned beneath the antenna to produce a two-dimensional image and it is here that the effect of the antenna can be seen. The molecules can be resolved with a resolution of 26 nm, three times smaller than the patterns associated with the aperture. This result demonstrates the tight confinement of the enhanced field at the end of the antenna.

I have been slightly involved with copper vapour lasers and these are more temperamental and unforgiving than an opera diva. Maintenance is frequent and complicated, and the slightest mistake in powering up or down will cause destruction of the equipment.

Why not instead try Argon ion lasers? Again Pentagon has plenty of experiences in extreme high power use, supposedly for direct communications with submerged submarines as the blue/green light

@Neil Cox #71

The sun not being a point source is an interesting issue. I have looked up in my old optics books but these don’t cover anything more fancy than two lens geometric optics. I had hoped the use of 2 or 3 mirrors would do the trick but I am unsure. I would like to hear from someone experienced in optical design. If not there is always the possibility of using sunlight pumped parametric amplifiers.

I’ve been ignoring the laser options as probably not feasible, but I had time to do a little research, and I may have something workable.

First some useful facts. There is a window from about 0.25-0.3 microns to perhaps 0.8 microns (near UV, visible light), as well as several somewhat “dirtier” windows in the near IR. Here is a graph of the atmosphere’s transmittance between 0.4 and 2.5 microns. The direct beam transmissivity is a little higher than the figures in the graph I linked, so I suspect this one is integrated over a hemisphere. My source is page 118 of Marshak and Davis. Beyond the range of the linked graph, it shows a dirtier window around 3.5 microns, and an even dirtier one at around 10. (This is the thermal IR region involved in the greenhouse effect.)

After that, the atmosphere is essentially opaque, until you get to a very dirty window peaking at about 3.5 mm, a somewhat better one at about 10 mm, and it’s transparent from about 18 mm up. Those are the wavelengths available for power transmission.

An advantage of using lasers feeding PhotoVoltaic cells is that such cells have a “natural” voltage they operate at (the band gap), and maximum efficiency will be obtained at a color with a photon energy just a bit above that (in electron volts). I presume this is how you expect to get the 50% efficiency for the ground station (since lasers are monochromatic). To convert from wavelength to photon energy, go here.

Now, for efficiency at the power station. I’ll point out that the correct efficiency is not the ratio of power output to solar power received, but a ratio of power output to station mass. This permits a technology that was (1/2) mentioned above: solar pumped superradiant gas lasers. The best-looking type I could find is based on copper vapour, but there may be other metal vapours that would work better.

To make a gas like copper vapour superradiant, a very long path is required (AFAIK). The beam will have to primed with the output of a standard gas laser with a proper cavity, which is then focused by a 15 meter mirror down a tube of plasma 15-20 meters in diameter and several hundred meters long, which is at the focus of a parabolic cylindrical mirror focusing sunlight to pump it. (The priming laser will have to use the same gas as the main amplifier, I’m assuming copper vapour here.)

Now, let’s assume an energy efficiency for the laser of 1%. A square kilometer of mirror can capture, say, 10^9 watts, which means we’re left with 10 megawatts in the beam, say 4 megawatts delivered at the wire on the ground. A square kilometer of 10 micron aluminized film might mass 25 tons, let’s assume 75 tons for the supporting structure. For containing the metal vapour (plasma), assuming a magnetic field generated by a coil of aluminum 1 square cm. in cross section, 15 meters in circumference, wrapping once per meter, that adds up to ~15 tons. You’d also need power for the current and the priming laser, presumably from PV cells, as well as the priming laser itself, metal vapour handling structure, etc. If we assume a total mass of 400 tons, that’s 10 KiloWatts delivered per satellite ton. I don’t know whether that’s economical, but it’s certainly possible to put into orbit.

To Do:

To pursue this option, several things must be researched.

1. The available metals must be evaluated for their behavior as plasma (especially containability) and their effectiveness as lasing materials. Typically, the pumping energy is somewhat higher than the output photon energy, and the pumping energy shouldn’t be higher than blue light, yellow would be better. The laser output color should probably be orange or yellow, depending on the capacities of the receiving PV systems. A metal must be selected, ideally matched to the band gap of the PV cells to be used.

2. Plasma containment technology must be investigated and a proposed design developed. Leakage must be estimated, as well as power requirements for the magnetic field(s) involved. I suppose superconductive magnets could be considered, although keeping them cold under those circumstances would probably require more energy (and weight) than using aluminum.

3. A mirror technology must be selected and a design created. Although I’ve been assuming a parabolic cylinder, with a 15 meter plasma beam a set of flat stretched film mirrors several meters across would be sufficient, if they were lighter.

4. All the final designs must be created with the launch considerations in mind, as well as the effects of cosmic radiation in GEO.

Hopefully, this will get the design onto the table for consideration. It needs a good deal of expert help, especially regarding the laser design, which is not the sort normally used today.

California Valley might soon get a few shiny new neighbors, from a solar power plant proposed for rural San Luis Obispo County.

P.G.&E. and Ausra energy have announced plans for a 177 megawatt power plant using flat mirrors to make the plant cheaper and more efficient.

The project would be located between Paso Robles and Bakersfield near the Carrizo Plain.

The plant is being proposed for a sparsley populated area on one square mile of land that Ausra already owns near the Carrizo Plain National Monument.

Power companies must provide 20 percent of their output from renewable “clean” resources by 2010.

The plan will take a year to review, with possible construction starting by 2009.

http://www.msnbc.msn.com/id/21645102/

t says: Nearly every form of power is reliant on subsidies, be it coal, oil, or nuclear. In 2004, $150 billion was made available to subsidize fossil fuels, with $53 billion dedicated to coal alone.

Me: A square mile is about 2,600,000 square meters. 177,000,000 watts divided by 2,600,000 = 68 watts per square meter, so they are getting high utilization of the one square mile, unless most of the flat mirrors will be on adjoining property. Since a flat mirror on a tower is no uglier than a cell phone tower, the neighbors may be cooperative. The mirrors can be turned to provide extra light in yards and gardens when the angles (or light level) are wrong for the photovoltaic panels. It is challenging to get much more than 68 watts per square meter except at 1 pm on June 21, as the mirrors will shade each other and some of the photocells early morning and late afternoon. Also walkways must be provided to clean a large photovoltaic array and do other mantainance. The panels would be much more costly to allow walking on them, plus their working surface is likely dangerously slippery. A beam more than a mile long scatters some of the light beyond the photovoltaic panels, so it will be difficult to scale up to more than about 177 megawatts without some diminishing returns.
I would like to see “as built” results compared to promised results for some completed systems. Does anyone know where such data is available that is truthful? Neil