Heat from data centers can be stored in the ground and recovered months later, when buildings need it. Water carries waste heat from servers down a borefield of pipes in summer, and the surrounding rock holds that warmth because it conducts heat poorly. In winter, water pumped back through the same pipes comes up warmer than it went down. Epic Systems in Wisconsin has used this for about two decades, with roughly 6,100 wells heating and cooling around 40 buildings on its campus. Storage is the missing piece, since servers produce heat all year while buildings need heating for only about four months in most of the U.S. Heat pumps then make the stored warmth efficient to use, and the Department of Energy reports the buildings use about 25% less energy than comparable ones. A similar aquifer system in Bonn, Germany has supplied 60% to 80% of winter heat for a complex that includes a data center since 2009.

Hampi is a UNESCO World Heritage Site in Karnataka, India, with more than 1,600 surviving remains spread over 4,100 hectares. It was the capital of the Vijayanagara Empire from 1336 to 1565. Travellers from Persia and Portugal described it as a prosperous, wealthy and grand city with temples, markets and farms along the Tungabhadra River. By 1500 it was estimated to be the world's second-largest city after Beijing, and probably India's richest at the time. In 1565 a coalition of Muslim sultanates defeated the Vijayanagara Empire, its capital was conquered and destroyed, and the city was left in ruins. Hampi remains a religious centre, with the active Virupaksha Temple at its heart.