“In summary, meaningful global controls on CO2 emissions will not be instituted before alternatives to fossil energy become competitive. At that time, policies to force reduced fossil use will be unnecessary. In the interim, policies encouraging basic research to lower the cost of new energy technologies, limiting the harmful consequences from climate change, or contending better with damaging events of all sorts would yield greater expected benefits for comparable expected costs. For the United States and Canada, in particular, constraining fossil fuel use over the next few decades will come at a high cost in terms of reduced energy security.”
Wiki: In 2008, total worldwide energy consumption was 474 exajoules (474×10^18 J=132,000 TWh). This is equivalent to an average energy consumption rate of 15 terawatts (1.504×10^13 W].
What world needs is a new source of energy which equal of more than 15 terawatts.
Solar energy in space per square km is: 1300 watts per sq meter times one million. At with solar panel at 20% efficiency it’s 260 watts generated power per square meter,. so 260 MW per square km. In space one has millions to billion of square km one could harvest solar energy. There more square meter of area available in space than entire earth surface- and using this area in space has zero negative impact upon people on earth. So space can a source of thousands times more than 15 terawatts. And such a source of energy last for millions of years.
A solar panel in space has 4 times the energy density as solar panel has on earth has- and it’s constant supply of energy- it has 24 hour a day, of constant energy. So solar panel in space gets more twice amount sunlight as panel on does during daylight, plus get same amount during night on earth. Or earth gets about 6 hours of 1000 watts of solar flux- and space gets +1300 watts for 24 hours.
The reason this is not already being done, is getting off of earth is expensive. We are in a deep gravity hole. The moon is in relatively small gravity hole. It would fairly bad idea to make solar panels on earth and ship them into space. It could be done, it’s just not a very good idea.
You don’t have make solar panel on the Moon- there could other to get material- one could mine asteroids.
Now fusion is also a possible source of endless energy- but we can’t do that because we don’t know how. We know how, to mine and make solar panels on the moon, in same degree as we know how to make some huge bridge, building, or ship. It’s technically and managerially challenging- but with fusion we can’t do it yet- maybe never can do it.
One thing essential to know, is that the high cost of getting into space, is not mostly a matter of physics. But instead it *largely* a matter of market. Getting into space is similar to early day flying airplanes. The advantage aircraft had over what spacecraft has, is aircraft had a potential of a large fairly easy to see market. But this market had to be developed- costs had to lower, people had to be convinced that flying was first, “fun” and somewhat safe, finally it was practical way to get from point A to point B.
Space travel, more precisely suborbital travel, may in next few decades be a practical way to travel to different places on earth- anywhere on earth in about an hour. If that is accomplished, that will a huge market for “space travel”. If that happens getting to the Moon or Mars will a lot cheaper and easier [it's quite different- not it has important similarities]. There are about 4-5 players [one being Virgin Galactic] trying to go in this direction- first step being joyrides and science payloads.
So my point is not that we go to moon and start building solar panels- that would like trying build a 747 in the 1920′s. My point is this is option in the future. You talking about 40 to 50 years in future. This could done in 40 to 50 years into the future, but we need to do some stuff first.
And it’s not so much that technology has to evolve first, but more importantly markets need to evolve first. We could have started this 40 to 50 years ago- we didn’t gained any needed technology that’s enabling it today. And it possible that 40 to 50 years from now, that no significant progress is made. We could will still be 40 to 50 year from being able to do it. What is required is for NASA to explore the Moon- and explore the moon with a specific purpose. That purpose is to determine whether there is *minable* lunar water and where it is more precisely that we guessing where it is today. And this lunar would then need to be mined- but not mined by NASA. NASA has limited budget, and it’s job is exploring space, not mining or farming in space [or mining or farming on earth]. Once NASA is finished with Moon [something achievable within about 10 years] it then must explore other places- such as Mars.
But almost as important, NASA needs to support a market for rocket fuel in space. And needs to do this right now, and continue doing this after it goes to Moon and afterwards goes to Mars. The importance of lunar water, is you make rocket fuel. And having a market for rocket in space, is of course creating a new market, but is also allowing NASA to do it’s job at a lower cost. It makes going to the Moon and elsewhere cheaper.
And rocket fuel will start expensive, and become cheaper as a market develops [develop meaning more players are buying rocket fuel than NASA- other govts, and other non-profit and for profit entities.
This may all happen “despite” what NASA does, but NASA should making it happen, sooner, rather than later.
Now what happens, when make rocket fuel from water is you need electrical power- so this starts a market from electrical power in space- right now the cost of electrical power is more than $10 per Kilowatt hour,
and getting below $1 per kilowatt hour would something one could expect within a few or several years, and within a decade or so it be near around the cost we paying for solar power on earth. At that point, large investment might be possible to drive down cost considerable lower than solar power on earth, and in order to sell it to Earthlings. But before this there would research developing means of achieving production a lowest costs.
Point is isn’t a sure path- you can’t have governments throwing money at it- there is a learning curve.