Nuclear power is not only expensive, it's potentially the most insidious vehicle of climate change. Granted, it's not yet implicated in today's problems but its widespread use will most surely destroy the earth. Don't forget that there is no know means of eliminating the extremely radioactive waste - waste that is toxic to all know forms of life. Increase the number of nuclear power plants and the intensity of their use and it'll be only a matter of time before we irradiate the entire planet.
One another note: we're being sidetracked again by the big energy. Solar energy is simply the ultimate green energy so only two primary issues need to be addressed when it comes to our energy needs; 1- who owns/controls it, and 2- how cheap is it. The two are the primary objectives of big energy giants and they do their best to distract us from this truth.
To the point of how much space it takes to generate sufficient power - there is no need to use any more space than the buildings we already have. In most cities, buildings and parking lots make up the major use of land space. simply requiring these building to be outfitted with solar panels and tied into the grid would provide sufficient energy for most of a city. Big energy is wasteful in almost every aspect. They must necessarily use extra space for solar because they must over-generate in order to compensate for the waste of transmission lines and must waste energy because they generate based on anticipated rather than actual need.
On the other hand, when we own our own solar energy generation system we can make energy more cheaply. Individuals can be encouraged to outfit their own buildings with solar power at the same cost as a few years of energy bills from their friendly neighborhood utility and after that they'd pay only minor dollars to upkeep their system. The potential cost saving is staggering when you consider the lifespan of most buildings and most people. For most of our 40-60 years of adult life we could be living nearly cost free for clean green solar energy. How's that for cheap energy with no added environmental stress from land use or big energy companies!