Spain. Solar Towers, Spain. In a patchwork of agricultural fields outside Seville, Spain, two otherworldly towers rise above the plain. Nearby arrays of mirrors reflect light onto the towers, illuminating the water vapor and dust suspended in the air and creating visible beams. Within the towers, the thermal energy from the concentrated light creates steam, and the steam powers turbines to generate electricity. Known as PS10 and PS20, the mirror-tower networks are part of a larger project intended to meet the energy needs of some 180,000 homes -- roughly the energy needs of Seville -- by 2013, without greenhouse gas emissions. [NASA]