In today's world, with populations and economies booming, the demand for energy is rising. A portfolio of energy sources is used to meet this demand. Because there is no perfectly clean, safe, and inexpensive source of energy, the makeup of this portfolio involves tradeoffs of safety, cost, and—of increasing concern—emissions of greenhouse gases such as CO2. (If you haven't completed the Carbon lab, we recommend you start there). In this lab, your challenge is to try to meet the world's projected energy demand by choosing from the available energy sources, while keeping atmospheric CO2 under control and avoiding the particular limits and pitfalls associated with each energy source.