Want to see the greenest land on earth, where fossil fuels are almost fossils themselves? Look to an island in the North Atlantic the size of Kentucky.

I went to Iceland recently to see the fjords, drive a car fueled by hydrogen, and eat whale sashimi. Unfortunately, the car — a modifi ed Toyota Prius — was noisy and underpowered. The sashimi was a bit gamey for my taste. But Iceland? Beautiful. Surprisingly hip, supremely hi-tech, and — despite recent economic turmoil — bullish about its future.

But the coolest thing about this country of 300,000 is that it runs almost entirely on water.

Eighty percent of Iceland’s energy comes from hydroelectric dams and geothermal plants. That’s largely because Iceland has no forests, no coal, and no oil, save for a few undersea fi elds. But it does have vast reservoirs of superheated water thousands of feet underground. In fact it’s hard to drive more than a few miles outside Reykjavik without seeing pools of bubbling mud or steam venting from the moss-covered lava fi elds.

To build a geothermal plant, Icelanders drill 2,000 meters or more into the earth and bring up water heated under pressure to more than 400 degrees Fahrenheit. The plant separates the steam from the water and uses it to spin turbines. It sends some of the water down miles of pipes to heat homes; the rest gets pumped back into the earth. (Some of it also gets diverted to The Blue Lagoon, an outdoor spa where the waters are medically endorsed for treatment of skin ailments like psoriasis.)

Iceland has more geothermal energy than it can use. But you can’t really export steam, so Icelandic companies are doing the next best thing: exporting their geothermal expertise to the rest of the world and helping to build plants in Canada, China, Europe, Southeast Asia, and the U.S.

As with wind farms and hydroelectricity, you can’t build a geothermal plant just anywhere. You need to be over “hot spots,” where the tectonic plates meet. Hot spots are found in the Pacifi c Ring of Fire and big swaths of Africa, the Mediterranean, and the Middle East. Using Enhanced Geothermal Systems, water is pumped underground and turned to steam using the earth’s internal heat; this process opens up the possibility of using geothermal energy in even more territory.

Though building a geothermal plant is more expensive than building an oil refi nery or a coal plant, the steam used to produce geothermal power is free and therefore immune to the wild price fl uctuations we’ve seen with oil. The energy that feeds into the power grid is always on and available at its source — and it’s a lot cleaner. Right now the world is using a fraction of the geothermal energy available. According to the U.S. Geological Survey, the earth contains enough heat energy to power the world many times over — if we develop the technology to tap into it.

Iceland’s next eco-challenge are the cars and trucks that consume the remaining 20 percent of its energy. The country’s experiments with hydrogen-fueled cars never really took off, but next year Mitsubishi is introducing a fl eet of i-MiEV electric cars to the island. The government plans to build charging and battery swapping stations to service the fl eet, in hopes of achieving its goal of 100 percent renewable energy by 2050.

Meanwhile, by tapping into the energy under its rocky soil, Iceland hopes to become the cloud computing hub of Europe and feed cheap and clean electricity to powerhungry data centers. Microsoft, Cisco, Google, and Yahoo are among the companies looking to build computing centers there. Welcome to the 21st century, powered — at least in part — by steam.