Energy demand will double in the next 50 to 70 years, requiring considerable leaps in clean, reliable, and affordable energy. There is a menu of opportunities to decarbonize and this issue will examine one: Carbon Capture and Underground Storage, or CCUS. Why do we need CCUS? A simple analogy follows: think of our atmosphere as a bathtub and the water as CO2. Our atmosphere is becoming an overfilled bathtub; to keep the bathtub from overflowing, we must turn down the tap and remove the plug. That’s where Carbon Capture Utilization and Storage (CCUS) comes into the energy sustainability picture.