The need for sustainable energy continues to rise. According to one study completed by BP, energy consumption across the globe has increased 5.3% within the year, the largest spike since 1973. The digital nature of our lives is largely responsible for this spike. It takes as much as 35 times more energy to produce an equal amount of smartphones as it does for books. Though some progress has been made to improve the performance of bio-fuels and solar panels, some cities are focusing their attention on the energy beneath their feet.

Geothermal energy is the result of near-constant heat beneath the earth’s crust, which is then able to be turned into different forms of power. Heat, in the form of steam and hot water, located deep underground is accessed by tapping into the crust’s natural fissures. This heat is then converted into an inexpensive renewable energy source. Theoretically, geothermal energy can be transmitted to distant location, but current levels of technology is most beneficial to cities located near hot springs or along the continental plate boundaries.

There are five cities in particular whose use of geothermal technology stands out. They represent the future as we discover new ways to tap into the power that our planet produces. Here are some of the highlights for each of these cities:

Boise, Idaho

Geothermal technology has been in use in the city since the early 19th century. Today the city runs the largest direct use system in America, taking advantage of water that is hotter than 170 degrees. The Boise Public Utility provides heat for nearly 60 businesses located in four independent geothermal heating districts in the downtown area. The system, which also provides hot water for recreation and heat for the city’s greenhouses, provides cost savings that equal the cost to heat 500,000 square feet of space with conventional heating methods annually. The state’s capital building and even some private residences are heated by other privately managed geothermal technologies.

The program has been so successful that a concerted effort is was also made to provide geothermal heating to nine buildings on the Boise State University campus. Today, geothermal heating is provided to over 4.5 million square feet of space across the city of Boise.

Reno, Nevada

When ranked according to installed geothermal energy capacity per person, Nevada holds the top position in the nation. Its untapped geothermal resources are the largest in the United States. Reno, the “Biggest Little City in the World,” significantly benefits by the use of geothermal energy. Their system provides competitively priced electricity for the more than 225,000 residents of the city.

The city produces an amazing 100 megawatts of power, which is more than enough to meet all the power needs of every residence in the city. Ormat Technologies, a publically traded company, is in charge of managing the majority of Reno’s geothermal baseload at the multi-plant complex that it owns. The innovative company has even developed a means of increasing power production when the High Desert temperature soars, with their evaporative cooling system.

Reykjavik, Iceland

Iceland is well-known for their volcanoes, which are now being used to produce clean power by harnessing all that geological activity. All but about 10% of Iceland’s buildings and homes are now heated by the naturally heated water located beneath their feet. In fact, they even take advantage of the prevalence of geothermal energy to heat parking lot floors to reduce snow during the winter.

Geothermal energy is largely responsible for Reykjavik receiving the honorable title of “Greenest City in the World.” Nearly half of the citizens of the country live in the capital city, whose name literally translates as “Smoky Bay,” highlighting the enormity of the untapped power lying under the city’s crust. Geothermal power has been in use for about 70 years for nearly everything in the city, and it is widely accepted as the means to pulling the struggling country out of a crippling recession, not only by providing inexpensive power, but also because countries developing their own geothermal technologies are looking to the city as a consulting model.

Masdar City, UAE

Though located in an extremely oil-rich country, Abu Dhabi, Masdar City is utilizing geothermal energy as a more sustainable alternative energy source. The city has formed a partnership with Reykjavik Geothermal to develop a successful geothermal process that now provides the city electricity and heat. The cities approach is different than other cities that rely on nearby hot springs, however, it takes advantage of a new technology called Enhanced Geothermal Technology. Rather than depending upon an endless supply of water from hot springs, fissures are created in the ground into which water is pumped resulting in efficiently heated water that is used to create heat and electricity within a closed-loop system.

Despite that the initial testing of Masdar City’s geothermal potential didn’t produce water that was hot enough for efficient electrical conversion, they persevered and finally had a break through that enabled them to build a fully functional Enhanced Geothermal system.

Perth, Australia

Australia has enormous potential underneath its surface, according to Hot Dry Rocks, a geothermal energy consultant company. Using only about 2% of the resources that the country has available could produce as much as 10 times the electricity that is currently than is currently produced through coal and gas.

The reason for this is that the entire country has a layer of granite under its surface, which traps heat, allowing it to heat up to the perfect geothermal temperature in excess of 400 degrees Fahrenheit. Habanero, Australia’s aptly named deep-end onshore well, is testing the use of hot granite to produce geothermal energy near Perth in Cooper Basin. Using a second well that was installed specifically for the purpose, a complete geothermal circuit for testing energy output was established. If the tests are successful, Perth will begin producing low-cost electricity for its citizens.

These five cities represent the cutting edge of advances in geothermal technology advancement. Without a doubt, their success will inspire even more cities to take the steps necessary to produce their own geothermal electricity and heat, thereby helping to provide some relief to the world’s reliance upon coal and oil for its energy consumption.