The lecture begins a discussion of present and future energy demands and the ways in which we invest in different forms of energy by focusing on nuclear energy use globally. The risks associated with nuclear energy are described, including risk of human error leading to a mass evacuation event, and the challenges faced in finding an adequate nuclear waste storage facility for the United States. Such a facility would be need to be able to store nuclear waste for a million years or more, due to the long half-lives of nuclear waste. The lecture describes the disaster that took place at Chernobyl nuclear plant, and the wide-ranging effects of that disaster on the natural and built environments as well as human health.