Ethanol disaster was as much a commercial group scratching the government for guaranteed profit as anything else. I believe a for profit company helped push this problem upon us:
"One reason has been the willingness of the Archer Daniels Midland Company, by far the country's largest producer of ethanol, and of the company's chairman, Dwayne O. Andreas, to donate generously to politicians from both parties.

Last year, according to calculations by the Center for Responsive Politics, a nonpartisan watchdog organization, Archer Daniels, its executives and its political committee gave more than $1 million to the political parties and candidates for Federal office, divided more or less evenly between Republicans and Democrats. In 1992, more than $1.5 million was donated, more than $1 million of it to Republicans"
http://query.nytimes.com/gst/fullpage.html?res=9C0DE6DE113EF931A15755C0A961958260

So profit is a (NOT) great indicator of value.

If you follow the link (very last thing) from the originating posted PDF, you find the meatier document with far more feasibility background info. There's some great info llke this: "Every 1 km-wide insolation band at GEO receives nearly as much energy per annum(year) as the content of the entire 1.28T BBLs of recoverable oil remaining" & this points to why space is more efficient than ground: "Our Sun is the largest known energy resource in the solar system. In the vicinity of Earth, every square meter of space receives 1.366 kilowatts of solar radiation, but by the time it reaches the ground, it has been reduced by atmospheric absorption and scattering; weather; and summer, winter, and day‐night cycles to less than an average of 250 watts per square meter."

Actually, a lessening of solar radiation would be welcome to help slow down AGW. Unless of course you disbelief in 95% of the climate science. (http://www.realclimate.org/index.php/archives/2004/12/index/#Responses)

Microwave/ or Laser (IR) has been thought of as the most efficient transfer mechanism, in current proposals.

Also, I would like to say this is great long term National and International Goal that can excite and energize the world population. I believe sociology/psychology says that without goals, humans tend to stagnate and decline. This would, as mentioned above, with International involvement, perhaps get the whole world on more peaceful terms.

Because, historically, massive changes have required government sponsorship. Think about the (European) discovery of America. Needed some capital from Spain, I recall. I believe railroads, and even earlier, canals were partly government planned and sponsored. How about Highways, how much profit has been made from trucking. I believe there is significant government involvement in that. Would you take all the highway funding back?

I am a little concerned about DOE being put near this. For the most part DOE is an extension of the Military, keeping track of Nuclear weapons, and trying to cleanup past efforts in mining and refining of Uranium. In their other efforts, around generating new energy research, they have bluntly, sucked. They are currently staffed (upper tier) with Fossil fuel lobbyists, and really try to help out oil companies. DOE should be given a 'haircut'.

SSP is the destination we should aim at on the road to total energy self sufficiency. There may be waystops along the road, like wind, ground solar, LNG, etc. but this is the free-est and most renewable source for energy. This also has the most capability of being (eventually) green.