Sodium nitrate in the context of Potassium nitrate

A solar power tower, also known as 'central tower' power plant or 'heliostat' power plant, is a type of solar furnace using a tower to receive focused sunlight. It uses an array of flat, movable mirrors (called heliostats) to focus the sun's rays upon a collector tower (the target). Concentrating Solar Power (CSP) systems are seen as one viable solution for renewable, pollution-free energy.

Early designs used these focused rays to heat water and used the resulting steam to power a turbine. Newer designs using liquid sodium have been demonstrated, and systems using molten salts (40% potassium nitrate, 60% sodium nitrate) as the working fluids are now in operation. These working fluids have high heat capacity, which can be used to store the energy before using it to boil water to drive turbines. Storing the heat energy for later recovery allows power to be generated continuously, while the sun is shining, and for several hours after the sun has set (or been clouded over).

The territory of Chile has been populated since at least 3000 BC. By the 16th century, Spanish invaders began to raid the region of present-day Chile, and the territory was a colony from 1540 to 1818, when it gained independence from Spain. The country's economic development was successively marked by the export of first agricultural produce, then saltpeter and later copper. The wealth of raw materials led to an economic upturn, but also led to dependency, and even wars with neighboring states. Chile was governed during most of its first 150 years of independence by different forms of restricted government, where the electorate was carefully vetted and controlled by an elite.

Failure to address the economic and social increases and increasing political awareness of the less-affluent population, as well as indirect intervention and economic funding to the main political groups by the CIA, as part of the Cold War, led to a political polarization under Socialist president Salvador Allende. This in turn resulted in the 1973 coup d'état and the military dictatorship of General Augusto Pinochet, whose seventeen-year regime was responsible for many human rights violations and deep market-oriented economic reforms. In 1990, Chile made a peaceful transition to democracy and initiate a succession of democratic governments.