Why are we developing anything other than Space-Based Solar Power? 

Advantages of Space Solar Power

• Unlike oil, gas, ethanol, and coal plants, space solar power does not emit greenhouse gases.
  
• Unlike coal and nuclear plants, space solar power does not compete for or depend upon increasingly scarce fresh water resources.
  
• Unlike bio-ethanol or bio-diesel, space solar power does not compete for increasingly valuable farm land or depend on natural-gas-derived fertilizer. Food can continue to be a major export instead of a fuel provider.
  
• Unlike nuclear power plants, space solar power will not produce hazardous waste, which needs to be stored and guarded for hundreds of years.
  
• Unlike terrestrial solar and wind power plants, space solar power is available 24 hours a day, 7 days a week, in huge quantities. It works regardless of cloud cover, daylight, or wind speed.
  
• Unlike nuclear power plants, space solar power does not provide easy targets for terrorists.
  
• Unlike coal and nuclear fuels, space solar power does not require environmentally problematic mining operations.
  
• Space solar power will provide true energy independence for the nations that develop it, eliminating a major source of national competition for limited Earth-based energy resources.
  
• Space solar power will not require dependence on unstable or hostile foreign oil providers to meet energy needs, enabling us to expend resources in other ways.
  
• Space solar power can be exported to virtually any place in the world, and its energy can be converted for local needs — such as manufacture of methanol for use in places like rural India where there are no electric power grids. Space solar power can also be used for desalination of sea water.
  
• Space solar power can take advantage of our current and historic investment in aerospace expertise to expand employment opportunities in solving the difficult problems of energy security and climate change.
  
• Space solar power can provide a market large enough to develop the low-cost space transportation system that is required for its deployment. This, in turn, will also bring the resources of the solar system within economic reach.

Disadvantages of Space Solar Power

• High development cost. Yes, space solar power development costs will be very large, although much smaller than American military presence in the Persian Gulf or the costs of global warming, climate change, or carbon sequestration. The cost of space solar power development always needs to be compared to the cost of not developing space solar power.

http://www.nss.org/settlement/ssp/index.htm