In Paris, about 7,500 buildings are heated using geothermal energy, a cost-saving and carbon neutral energy source. Water is drawn from deep below ground at a central location and heated by the earth, and then sent via underground pipes to individual buildings. The Bagneux and Chatillon district has scaled up the system, providing heat to over 40,000 people. Districts created joint ventures to reduce construction costs and residents do not notice the energy source shift because when the temperature drops to a point where geothermal energy is not viable, gas boilers automatically keeps the heat flowing.

Iceland, hit by the oil crises of the 1970s, turned to geothermal energy - and they haven't turned back. The island is now powered by 100% renewable energy, and they are taking it one step more, looking to further cut emissions using a unique carbon capture system called CarbFix. It is being pioneered at the Hellsheidi geothermal power plant in western Iceland.

Despite being an island of seamen, Iceland used to experience high numbers of drownings every year, fostering a keen interest in swimming education. The government stepped up and tapped into the underground hot water generated by Iceland’s volcanic activity to create geothermal pools, which quickly became more than a humble municipal investment, but perhaps the very secret to the country’s happiness. Every town now enjoys communal pools, which create a neutral, recreational space that brings all manner of people together.

Geothermal power is typically hard to scale due to its dependence on hot water. Climeon is a Swedish energy company changing the game. It uses low-temperature heat and sells its energy in modular units, which makes it affordable. Due to an infusion in capital, the company is scaling its energy distribution across the globe.

Kenya harnesses geothermal energy to power the nation. By developing naturally occurring geothermal areas at the East African Rift, they were able to supply almost half of the country's energy needs in 2015.