Are you on crack?
Hydroelectricity, Solar-power, Geo-thermal energy, Wind power.
Boy all of those alternatives are pretty dirty.
And as far as efficiency...even if you lose 20% of the energy transmitted by a solar cell, since the energy if essentially free after you install the infrastructure, do you really notice the 20%? $0 * 0.2 = $0
Maybe you were thinking about electricity generated by a coal burning power plant.
Hey, Canuck, how much electricity can you get from a solar cell in northern latitudes? How much area needs to be covered with them to power a city? How are solar cells made? What by-products are released, and what kinds of raw materials are required, and where do we get them? I don't know about you, but Geothermal power sources aren't available where I live :/ Not every place on this continent alone has the option of hydroelectric, either.
To recap, solar power, geothermal, and hydroelectric power are great and all, but don't work everywhere, aren't anywhere near "free," and have no affect on the efficiency of IC engines. And we haven't even gone into how "clean" they are.