SEP 02

This is pretty cool stuff, very impressive if it works and is fully functional by 2030. You're right though, it's hard to imagine that this is the most efficient, practical solution.

I love the Japanese imagination and ability to innovate, but they always seem to be "announcing" things that are still barely even in the beginning planning stages. Another thing I wonder, when government talks about alternative energy, they make it seem like so many billions seem like a lot of money, but that doesn't seem like its much when we are giving banks and the Pentagon trillions on a regular basis. It's seems like the "stimulus package" should have just went straight into building solar fields in the desert. If government should subsidize anything, make it power, and make it free for everyone. That would give the US a bit of an edge in the world marketplace in my opinion. I think the US could theoretically make so much power for so little money we could sell it to other countries.

1GW in 2030 is buttons. Consider the efficiency progress we have made over the past 20 years with Solar and Wind. Google has invested 10m in Geothermal (which I think is the future), you have low tech, but high return. Geothermal

http://earth2tech.com/2008/08/19/google-drills-1025m-into-geothermal/

What are they trying to do? Increase global warming by beaming more energy from the sun?

Expensive and non-ecogeek.

See U,
TOM.

Just to let you know this is the exact thing that they have in Gundam 00. I wonder which came first:Science Fiction or Science?

Writing from Congo, this put a smile on my face. Think ahead to 2030. Aridlands across the tropics, oceans covering many of our cities and agricultural lands, and the rest.

Here, in central Africa, we are already facing a major household energy crisis. We need solutions, not in 20 year's, but tomorrow. Most of all, we need an alternative to charcoal, otherwise we lose the forests (I'm referring to the Congo Basin, the second lung of the planet, and the healthier one).

We've explored the alternatives, and electricity is too high tech, too expensive, too slow, to solve the problem.

Combustible biomass briquettes, on the other hand are great. 2 days to train 6 people in briquette production, and 4 days later they've created a factory generating 20kw. All of that for US$ 285. We've started. By the end of the year, 1000 village factories will be working on briquette production in eastern Congo. That's 20mw for US285,000 before 2010.

(It also brings 6000 people and their families above the poverty line in war-torn Congo).

Sorry for the sales pitch, but it seemed relevant.

Emmanuel I think concentrated ground solar would be better in Congo, as you have a high rate of sunshine there.

At the likely optimistic figure, this is $21/W vs $5/W and dropping for ground solar (used 1/4 time) or $1/W for wind (used 1/3 time). The US group's 10MW unit estimate was $1000/W-- almost looks like a misprint because it's so expensive.

But would you allow an energy beam in your back yard? The people skeptical of EMF are surely going to be skeptical of health risks of a microwave beam, and likely block a project.

from the article:

"Transporting panels to the solar station 36,000 kilometers above the earth's surface will be prohibitively costly, so Japan has to figure out
a way to slash expenses to make the solar station commercially viable," said Hiroshi Yoshida, Chief Executive Officer of Excalibur KK, a Tokyo-based space and defense-policy consulting company. "These expenses
need to be lowered to a hundredth of current estimates," Yoshida said by phone from Tokyo.

I get the same number close enough. Current price to GEO $20,000/kg; required for space based solar power to displace fossils by being substantially less expensive (1-2 cents per kWh) is $100/kg, a factor of 200.

Rocket Equation...

Needed 100 t/hr to GEO, $100/kg. Try a two stage to GEO. Required 14 km/sec, get the first 4 km/sec with a mass ratio 3 hydrogen/oxygen rocket. To get the remaining 10 km/sec with a mass ratio 2 means an average exhaust velocity of 15km/sec.

Because you stage far short of LEO, the second stage must have relatively high thrust so 60 km/sec ion engines won't do. Ablation laser propulsion (well understood physics) with an average exhaust velocity of 15 km/sec will provide over a g at 4 GW. The suborbital path keeps the second stage out of the atmosphere long enough (15 minutes) for the laser to push the second stage into geosynchronous transfer orbit.

At 4 payloads an hour (working the laser full time), each payload to GEO needs to be 25 t. So the laser stage is 50 t, the first stage 50 t (16&#xst;ructure) and 200 t propellant. On takeoff it masses 300 tons, less than a 747. A large airport handles a lot more traffic than 8 747 takeoffs and landings an hour.

Hard engineering, no miracles permitted. Not easy, the laser might eventually cost $40 billion. To get started (to positive cash flow) came out to $60 billion on a first cut proforma analysis.

A UK company, Reaction Engines, has an inordinately clever approach to boost the effective exhaust velocity so as to actually put positive payloads into LEO with hydrogen/oxygen single stage to orbit. What they are doing is recovering a lot of the energy that goes into liquefying hydrogen and using that to compress air to rocket chamber pressures up to 26km and Mach 5+. Google for them. Also Google henson oil drum for details.

I wonder how the costs would change if we had a space elevator?

hummmm. Kind of a defeatist attitude but totally justified. What we need is a global consortium with funding to go up next year and try this out. 2015 is too far off.

I agree that people uncomfortable with allowing the energy transfered back will add to the costs (reception at sea, etc). If this energy was used to provide power to existing and future space based technology, we can have a "gas station" for the smarter destination of this technology's use: Harvesting Asteroids for their raw materials.

When we can obtain space based raw material, we no longer need to use energy to put earth-mined dense materials into space. Elon Musk said the first Trillionaire is to be made in space. Conquering the high energy cost of both putting earth objects in space as well as the energy cost of moving those objects around (better sources of energy) will be a significant step in furthuring our reaches from our pale blue dot.

The only thing that justifies this expense is that it is stage 1 testing for a bigger program. There is Helium-3 on the Moon that can be used for fusion, but how do you get the energy back to Earth? This experiment allows them to test out energy beaming on a smaller scale.

Adam wonders about cost using space elevators. If we had the material for an elevator, it would be the way to go. Even if the elevator costs $800 B, for 100 tons per hour it would get the cost down to $100/kg.

But we don't have the cable.

A lunar elevator through L1 might be within existing materials. Working on that.

At a million dollars a flight and 25 tons of that reaching GEO, the cost for the first stage is $40/kg. 8 GW of laser at $10/watt written off in ten years is $8 billion a year. (plus energy fed back internal to the company). 100 t/hr is ~800,000 tons per year or 0.8 B kg. I.e., the laser part of the lift would cost $10/kg. Total (without labor and overhead) is $50/kg to GEO.

At 100 flights a day using $300 million dollar rocket or rocket planes that last 500 flights, a cost of a million dollars a flight seems reasonable, maybe even high. It only needs four km/sec of delta V (the lasers provide ten km/sec to the upper stage.)

This more than meets the 100 to one reduction in lift cost the Japanese say they are looking for.

There may be better ways, but at least this one will get the lift cost under $100/kg. That is where power satellites completely displace fossil fuels on cost.

For what it is worth, I don't think building a demo for microwave power transmission from space is worth doing. We have been sending microwaves down from space since the dawn of communication satellites. That isn't the block to building power satellites. The high cost of getting parts to GEO is.

Incidentally, a thousand workers at a GEO construction facility takes less than one percent of the 100 ton per hour throughput to support them. Thus robot assembly is not required.

I am not to concerned about the practicality of beaming energy down to earth and the overall cost.Think back into history and remember the practicality of going to the moon.The concept for a solar collecting satellite that beams energy down to earth is more about the technology that will be created.Beaming energy safely may be an alternative means to power personal transportation.Smaller battery and cancer causing energy waves, it will great.