Earth Sciences, Desalinization, tidal power, and minerals from the sea

For ages a source of food and common salt, the sea is increasingly becoming a source of water, chemicals, and energy. In 1967 Key West, Fla., became the first U.S. city to be supplied solely by water from the sea, drawing its supplies from a plant that produces more than 2,000,000 gallons of refined water daily. Magnesia was extracted from the Mediterranean in the late 19th century; at present