Currently, the solution to managing all this heat is water, which serves as a coolant at data centers. The biggest centers use five million gallons of water per day—matching the daily needs of 1,000 homes. According to a study by The Washington Post, typing and sending a 100-word email requires the equivalent of a half-liter bottle of water. And up to 56% of the energy used to power data centers comes from fossil fuels, according to the Environmental Energy and Study Institute.