Renewable energy and nuclear power increasingly factor into the evolving American energy equation to replace polluting coal. Even some environmentalists acknowledge that nuclear is a viable emissions-free option to dirty coal while renewable-energy technologies continue to advance. Nuclear fission reactors generate electrical power by splitting the atomic nuclei of uranium. This process creates a massive amount of heat — thermal energy — and radiation. The resultant heat is in turn utilized to make steam from water that then moves turbine blades to drive generators to produce electricity. The steam is continually recycled back into usable water, as conservation is becoming an increasingly imperative concern at power plants and other businesses. In other words, decreasing power plant water consumption and wastewater discharge are important environmental issues. Instead of burning some material, nuclear power plants split uranium nuclei, as noted, without producing any air pollution in the process. In short, the heat that the fission of atoms produces is the reactor’s only fuel. In contrast, coal- and oil-burning power plants have been releasing air pollution for decades. Mercury, for example, harms the nervous system and the kidneys; particulates cause bronchitis and lung cancer; vanadium damages our respiratory system; and nickel causes convulsions. Nuclear reactors don’t spew any emissions that contribute to global warming, acid rain or smog. Advocates of nuclear energy consequently argue that nuclear power must be part of the U.S. energy mix to reduce air pollution and greenhouse gases. They also emphasize that nuclear plants are at present safer and note that no further accidents have occurred since the 1979 Three Mile Island one in Pennsylvania.