Sentence Completion

Complete the sentence with ONE word from the passage for each blank.

Iceland generates almost all of its electricity from renewable sources, drawing on the country's unusual geology. Powerful rivers fed by glaciers are dammed to produce hydroelectric power, supplying most of the national grid. The rest comes from geothermal plants, which tap the intense underground heat created by the island's volcanic activity. This same heat is also piped directly into buildings, so that the great majority of Icelandic homes are warmed without burning any fossil fuels.

Most of Iceland's electricity comes from plants powered by glacier-fed rivers. The remainder is generated from energy, and the underground heat also warms most Icelandic .