Hawaii’s plan to rid its electric grid of fossil fuels by 2045 is the most ambitious target set by any American state, but it shouldn’t come as a shock.

For island states and nations disconnected from mainland grids, the price of transporting diesel, oil, or natural gas often negates the benefit of cheaper fuel.

In Hawaii’s case, the state forks over about $5 billion per year to import oil to fuel power plants. As a result, Hawaiians pay the nation’s highest electricity rates.

Transporting fuel by ship also raises the risk of oil spills, such as the 2001 incident off San Cristobal Island in the Galápagos archipelago. Ocean currents carried most of the 150,000 gallons of oil away from the island, but scientists estimated it killed more than 60 percent of the marine iguanas on nearby Santa Fe Island.

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The cost and risk of importing oil has islands big and small emerging as renewable energy trailblazers, turning to wind, solar, geothermal, and hydropower.

Hawaii, United States

More than 12 percent of homes on Oahu, the state’s most populous island, have installed rooftop solar—compared to the national average of .5 percent. With a state policy of obtaining 100 percent of its electricity from renewable sources by 2045, Hawaii is ramping up solar, wind, and geothermal power from five active volcanoes.

(Photo: Frans Lanting/Getty Images)

One geothermal plant already exists on the Big Island of Hawaii, and it generates enough electricity to power about 4,400 homes. But live volcanoes aren’t always the safest places, and some native Hawaiians don’t like the idea of building power plants on top of the home of the fire goddess Pele.

El Hierro, Spanish Canary Islands

Last year, the smallest island in Spain’s Canary archipelago switched on a totally green grid. The $110 million project started in 2005, when construction began on the island’s wind and hydropower system, which consists of a 11.5-megawatt wind farm, hydroelectric plant, pump system, and two reservoirs.

(Photo: Desiree Martin/Getty Images)

The windy days typically bring more power than the island’s 10,000 residents need, so the excess power pumps water from one lake to another at a higher elevation. When the wind dies, the water is released to spin turbines to generate electricity.

Tokelau, New Zealand

The tiny South Pacific territory made up of three atolls has gone fully solar. In 2012, Tokelau, population 1,500, mothballed its three diesel-driven power plants, which cost $800,000 a day to run, and installed thousands of solar panels, storing electricity in batteries for use when the sun doesn’t shine.

(Photo: Courtesy Tokelau.org)

Galápagos Islands, Ecuador

Spurred by the near-catastrophic oil spill of 2001, Ecuador began considering environmentally friendly alternatives to diesel-powered generators. Officials settled on wind in 2008 despite concerns that turbines posed a risk to the islands’ birds. The 2.4-megawatt wind farm has cut the island’s diesel fuel use 32 percent.

(Photo: AFP/Getty Images)

And last year, the Galápagos began operating the world’s first green airport—powered by three recently completed wind turbines and a solar array.