What are the avenues to significantly decrease data centre energy consumption?

Data centres consume large amounts of energy, both for power and for cooling/air-conditioning. As computing becomes even more pervasive worldwide, data centres and the amount of energy they use will increase even further. Making data centres more energy efficient hence will contribute significantly to a more sustainable planet. What indeed are the innovative and effective avenues and solutions for dramatically reducing energy consumption by data centres?

How will it have a positive impact?

Energy Security

Economic Benefits

Who will it have a positive impact on?