The fuel price alone for natural gas fired plants is 5 cents per kwhr. That price fluxuates wildly based on other demands. The fuel price for coal plants is probably about a penny per kwhr. Obvously it's free for wind power. Wind power is already competitive on price with gas but will have to be developed more to compete with coal.
Passive solar is fine but it takes people who will adjust to using it rather than the normal mentality of flipping a switch for instant power/heat/cool.
Passive solar just means your house is way cheaper to heat. My parents heat their house for about 150 bucks per year, with electricity, here in cold ole Iowa. That's about 1/10 to 1/20 as much as a standard house.