Arizona Solar Center Blog

Geothermal energy is a renewable resource; about 95 percent of the hot water in geothermal reservoirs began as cool rainwater. When rainwater seeps through cracks in the Earth's crust, it is heated by magma and turns to steam. The steam rises to the atmosphere, cools, turns back to liquid, falls back to earth as rain and eventually seeps back through cracks to be turned back into steam.

Arizona has an abundance of low-temperature geothermal areas, or hot springs, in the southeastern part of the state. Although the majority of these areas are not suitable for generating electricity, they do have potential for heating and cooling greenhouses, nurseries and fish farms.

The two highest temperature springs in the state are Clifton and Gillard, both in the Clifton-Morenci area of southeastern Arizona. The water temperature at these springs ranges from 158-180 degrees Fahrenheit. Even though temperatures may exceed 284 degrees Fahrenheit at depth, these two sites are only suitable for low grad steam. Neither of these areas has been developed.

More on geothermal energy here.

Modern excavations of many Classical Greek cities show that solar architecture flourished throughout the area. Individual homes were oriented toward the southern horizon, and entire cities were planned to allow their citizens equal access to the winter sun. A solar-oriented home allowed its inhabitants to depend less on charcoal - conserving fuel and saving money.

Ninety-three million miles away, the sun blazes energy toward Earth. When this energy reaches Earth, the energy transmitted in short wave-lengths (visible light, ultraviolet, etc.) penetrates our atmosphere and strikes the Earth's surface. Energy in long wavelengths (such as infrared, thermal radiation or heat) is absorbed by carbon dioxide and other gases in the atmosphere. When penetrating short wavelengths strike Earth, they are converted into long wavelengths (in the form of heat radiation) and reflected back toward space. Some thermal radiation escapes, but most of it remains trapped inside our atmosphere. These long waves build up and keep Earth warm. This phenomenon, known as the greenhouse effect, enables life to flourish on Earth. Its future effects are also the subject of much discussion.

Before and during the Middle Ages, the geared water mill spread from Rome throughout western Europe. The watermill was used to grind grain, saw wood and marble, and for turning grindstones. The scarcity of slaves and the value of draft animals for other uses may have accelerated its acceptance. These watermills formed the power base for civilization prior to the Industrial Revolution.

Updated December 11, 2013

Wind is often considered an indirect form of solar energy because wind currents are created when the sun unequally heats different areas of the Earth's atmosphere. It is renewable because the wind blows. In one 24-hour period, the wind blowing across the U.S. offers almost 14 times the energy used by the entire country. The problem arises in capturing that energy and putting it to use.

According to the late Carl Sagan, a world-renowned environmental author, the typical global temperature difference between an ice age and an interglacial period is three to six degrees Celsius (5 degrees to 11 degree Fahrenheit). Sagan theorized that if global temperatures were to rise three to six degrees C, water would become warmer and expand, melt polar ice caps and raise sea levels. Under these conditions, many islands would disappear and the oceans would flood such coastal cities as New York, Los Angles and Tokyo. Just a three-foot rise in sea level would triple the size of San Francisco Bay.

According to the late Carl Sagan, a world-renowned environmental author, the typical global temperature difference between an ice age and an interglacial period is three to six degrees Celsius (5 degrees to 11 degree Fahrenheit). Sagan theorized that if global temperatures were to rise three to six degrees C, water would become warmer and expand, melt polar ice caps and raise sea levels. Under these conditions, many islands would disappear and the oceans would flood such coastal cities as New York, Los Angles and Tokyo. Just a three-foot rise in sea level would triple the size of San Francisco Bay.

Passive solar homes (homes that are designed for natural heating and cooling) are popular in both mountain and desert areas of the state. Some of these homes have adobe, rammed earth, or straw bale as a building material.

Wind is often considered an indirect form of solar energy because wind currents are created when the sun unequally heats different areas of the Earth's atmosphere. It is renewable because the wind blows. In one 24-hour period, the wind blowing across the U.S. offers almost 14 times the energy used by the entire country. The problem arises in capturing that energy and putting it to use.