Data centers are an astounding, fast-growing service industry. Starting from nearly zero 20 years ago, Emerson Network Power estimates today there are 510,000 data centers worldwide with global revenues around $174 billion. The unbeatable value-added proposition offered by data centers is the massive collection and manipulation of raw data into real-time products, such as when Waze converts cell phone information into traffic advisories or when Alexa responds to voice commands. But data center growth creates a new set of problems. Most worryingly, data centers are huge.