Japan Hopes to have SPacebased Solar Power by 2030

[Crossroads Inc.]

Sure we've all heard this sort of thing before, and usually it Oie in the SKy stuff, but then again Japan is JUST crazy enough that they might get it done
LINK

Japan eyes solar station in space

TOKYO (AFP) – It may sound like a sci-fi vision, but Japan's space agency is dead serious: by 2030 it wants to collect solar power in space and zap it down to Earth, using laser beams or microwaves.
The government has just picked a group of companies and a team of researchers tasked with turning the ambitious, multi-billion-dollar dream of unlimited clean energy into reality in coming decades.
With few energy resources of its own and heavily reliant on oil imports, Japan has long been a leader in solar and other renewable energies and this year set ambitious greenhouse gas reduction targets.
But Japan's boldest plan to date is the Space Solar Power System (SSPS), in which arrays of photovoltaic dishes several square kilometres (square miles) in size would hover in geostationary orbit outside the Earth's atmosphere.
"Since solar power is a clean and inexhaustible energy source, we believe that this system will be able to help solve the problems of energy shortage and global warming," researchers at Mitsubishi Heavy Industries, one of the project participants, wrote in a report.
"The sun's rays abound in space."
The solar cells would capture the solar energy, which is at least five times stronger in space than on Earth, and beam it down to the ground through clusters of lasers or microwaves.
These would be collected by gigantic parabolic antennae, likely to be located in restricted areas at sea or on dam reservoirs, said Tadashige Takiya, a spokesman at the Japan Aerospace Exploration Agency (JAXA).
The researchers are targeting a one gigawatt system, equivalent to a medium-sized atomic power plant, that would produce electricity at eight yen (cents) per kilowatt-hour, six times cheaper than its current cost in Japan.
The challenge -- including transporting the components to space -- may appear gigantic, but Japan has been pursuing the project since 1998, with some 130 researchers studying it under JAXA's oversight.
Last month Japan's Economy and Trade Ministry and the Science Ministry took another step toward making the project a reality, by selecting several Japanese high-tech giants as participants in the project.
The consortium, named the Institute for Unmanned Space Experiment Free Flyer, also includes Mitsubishi Electric, NEC, Fujitsu and Sharp.
The project's roadmap outlined several steps that would need to be taken before a full-blown launch in 2030.
Within several years, "a satellite designed to test the transmission by microwave should be put into low orbit with a Japanese rocket," said Tatsuhito Fujita, one of the JAXA researchers heading the project.
The next step, expected around 2020, would be to launch and test a large flexible photovoltaic structure with 10 megawatt power capacity, to be followed by a 250 megawatt prototype.
This would help evaluate the project's financial viability, say officials. The final aim is to produce electricity cheap enough to compete with other alternative energy sources.
JAXA says the transmission technology would be safe but concedes it would have to convince the public, which may harbour images of laser beams shooting down from the sky, roasting birds or slicing up aircraft in mid-air.
According to a 2004 study by JAXA, the words 'laser' and 'microwave' caused the most concern among the 1,000 people questioned.

[Mr Bean]

Upside, the Japanese will have solar energy in space, paving the way for other countries to try it when the technology is perfected.
Downside, the same technology used to transfer energy from space to ground would make a handy space based deathray.

Hopefully for just fighting the various Giant monsters they must worry about.

[GrandMasterTerwynn]

Upside, the Japanese will have solar energy in space, paving the way for other countries to try it when the technology is perfected.
Downside, the same technology used to transfer energy from space to ground would make a handy space based deathray.

Hopefully for just fighting the various Giant monsters they must worry about.

Only if you focus it onto a really small spot, and attain the dwell time necessary to achieve burn-through. While a SPS (solar power satellite) would be transmitting on frequencies where water vapor and the atmospheric gasses are broadly transparent, a useful SPS will still be a very long ways away from the ground. Beam spreading will be non-trivial at those ranges, hence the need for a giant energy collecting area.

Some of the earlier SPS schemes I've seen involved beaming the power to Earth via microwave; and collecting it via giant rectenna farms. The microwave irradiance was such that it was believed that you could safely grow crops on the same land that your rectenna farm was on, so we're not talking death-ray levels of irradiation here.

I suppose that, with all that being said, a space-based laser of that power meant to strike ground targets in an offensive manner would be readily distinguishable from a space-based power station; owing to the larger optical train and heftier radiators. One may also have cause to worry if the nation launching the station also deployed a number of other large satellites whose extra mass comes from the large mirror they've got folded up to serve as a laser relay.

[Sky Captain]

How are they going to launch all that hardware economically? Current launch costs at several thousand $/kg would make space based solar power too expensive to be competitive. Current Japan`s biggest rocket H-IIB can put only 8 tons of cargo intio geosynchronous orbit. To build viable space solar station would recquire rockets with much greater lift capability, at least like planned Ares V.
Do Japan have plans to develop such rocket?

[Zixinus]

The government has just picked a group of companies and a team of researchers tasked with turning the ambitious, multi-billion-dollar dream of unlimited clean energy into reality in coming decades.

It is not unlimited: it will depend on how fast and how well will the solar panels (if that is what will be used) degrade, both due to use and solar wind.

"Since solar power is a clean and inexhaustible energy source, we believe that this system will be able to help solve the problems of energy shortage and global warming," researchers at Mitsubishi Heavy Industries, one of the project participants, wrote in a report.

I think there may be a misquote here or the journalist missed a more nuanced opinion: this alone will not solve global energy problems, although it can certainly help to solve it.

The solar cells would capture the solar energy, which is at least five times stronger in space than on Earth, and beam it down to the ground through clusters of lasers or microwaves.

The advantage of this: depending on the orbit and other details, this is a 24/7 power source with little variation of input. A significiant problem with solar panels in Earth.

How are they going to launch all that hardware economically? Current launch costs at several thousand $/kg would make space based solar power too expensive to be competitive. Current Japan`s biggest rocket H-IIB can put only 8 tons of cargo intio geosynchronous orbit.

My thoughts exactly: I thought that the Japan Space administration didn't have its own launch platforms. Even though it seems I was wrong, we are still talking about a massive scaling up with rockets.

[Gilthan]

While I'm slightly hopeful, the odds aren't too good yet, as a lot more ideas get floated around than done in the end.

Although the first stage of sending up a 10 megawatt test satellite in 2020 would be relatively straightforward with available rockets, the economics of 1 gigawatt SSPS producing power 6 times more cheaply than its current cost in Japan could never work unless they had vastly better launch capabilities by 2030. Space solar power is superior to ground solar power in theory, yet not economically so if using launch like the existing H-IIb rockets which are $11000 per kilogram to orbit. The billion-dollar question is why on earth do they think this is workable, or, namely, do they have a good plan for reducing the launch expenses?

Technically, they actually could, though, if, for instance, the Japanese developed once again a brainchild of an innovative expert they once paid great attention to before.

In the early 1960s, Dr. James Powell at Brookhaven National Laboratory, along with Dr. Danby, developed the MagLev train concept, which subsequently gained the attention of the Japanese National Railway, and the operating commercial results of that work are pretty well-known today.

Much later, Dr. Powell went on to be a top developer on this design:

StarTram has the potential to greatly reduce launch cost, e.g., down to ~$20 per kilogram, while delivering very large launch volumes, e.g., a million tons per year compared to the present volume of ~1000 tons per year.

In StarTram, spacecraft are magnetically levitated and accelerated in an evacuated tunnel to orbital speed, i.e., 8 km/sec or greater, using the superconducting Maglev technology invented by Powell and Danby in the 1960’s and 70’s. Based on their inventions, Japan Railways is presently operating Maglev trains at up to 350 mph in the atmosphere with the speed limited only by air drag.

In StarTram, no propellant is required to reach orbital speeds, and the energy cost is extremely low. At 5 cents per KWH, energy cost is only 50 cents per kg to reach 8 km/sec, and 75 cents/kg to reach 10 km/sec.

The total length of the Star Tram launch tube is 1,561 km (969 miles). The system is divided into two main components: the acceleration tube, which is 1,280 km (795 miles) long and located on the earth's surface, and the launch tube, which is 281 km (174 miles) long with one end levitated to an altitude of 72,000 feet. For comparison, the Trans-Alaska pipeline covers 800 miles between the north slope of Alaska and the port of Valdez. The 1,280-km-long, 7-m-diameter acceleration tube is evacuated to reduce atmospheric drag on the vehicle and the resulting deceleration and heat gain. Pump stations located approximately every kilometer along the length of the launch tube evacuate air from the system.

The launch tube is levitated by the magnetic repulsive force between a set of high current superconducting (SC) cables attached to it, and a second set of parallel SC cables on the ground that carry current in the opposite direction. Using the multi-megamp capability of presently available commercial superconductors, large levitation forces can be generated on the launch tube, e.g., 4 metric tons per meter of length, at 20 km altitude. A current of 14 mega amps in the levitated cables and an oppositely directed current of 280 mega amps in the ground cables produces a repulsive force of 4 tonnes/m at an altitude of 72,000 feet above sea level.

The net upwards force on the launch tube (magnetic force minus launch tube weight) is restrained by a network of Kevlar tethers that anchored to the ground beneath. The tethers also stabilize the launch tube against lateral wind forces.

The Star Tram launch system uses two basic types of launch vehicles. One is a reusable launch vehicle (RLV) capable of carrying people and cargo to orbit. The other is an unmanned Hybrid Logistics Module (HLM) for one-way-to-orbit cargo transport (see Figure 4).

The RLV would have a gross weight of about 200 metric tonnes with a 70-metric tonne payload capacity. The RLV dimensions are 5 m x 5 m x 40 m (16.5 ft. x 16.5 ft. x 130 ft.). The HLM would have roughly the same dimensions.

The design of the StarTram system, including the Maglev acceleration tunnel, levitated launch tube, superconducting cables, tethers, and spacecraft, is described in detail. StarTram could launch at a rate of up to 1 spacecraft per hour, with a 200 ton gross takeoff weight that includes 70 tons of cargo launch. Speed would be 10 km/sec for spacecraft traveling to the Moon, with somewhat lower speeds for insertion into Earth orbit.

The projected capital cost of a StarTram launch facility is approximately 60 billion dollars. Total launch cost, including energy, amoritization of the launch facility and spacecraft, and operating cost, is approximately $20 per kilogram of cargo.

Almost all of the technology components needed for StarTram now exist in commercial form, including Maglev superconductors, tethers, cryogenic insulation and refrigerators, vacuum systems, etc. The StarTram spacecraft would require development and testing; however, in contrast to spacecraft like the Shuttle, StarTram spacecraft can be made much more rugged structurally and with much better thermal protection systems since the extra takeoff weight for these purposes costs very little. With a vigorous development program, StarTram could begin operation within 15 years from now.

Mixed quotes from:

http://www.spaceagepub.com/pdfs/Powell_2.pdf

http://science.ksc.nasa.gov/shuttle/nex ... Report.pdf