Natural Resources

Wind Power
Wind is in effect a form of solar energy. Sunlight falls unevenly on different areas of the earth, causing some parts of the atmosphere to be heated more than others. Since warm air is lighter than cool air and tends to rise, air moves as a result of this varying heating pattern. Approximately 2 percent of the sunlight that falls on the earth’s surface is converted to the kinetic energy of the winds, the energy of moving molecules of gas that cause a reaction in whatever they strike. Simultaneously, wind energy is dissipated via friction with the earth’s surface and within the wind itself. Only a very small portion of the wind’s energy can actually be used. Most winds occur at high altitudes or over the oceans and are therefore inaccessible. Even the most ambitious wind-energy schemes would tap only a small fraction of the total resource, somewhat kin to occasionally lifting a bucket of water out of the Amazon River. The wind is one of the most abundant and easily usable forms of solar energy. It is constantly renewed and, for all practical purposes, it does not deplete.

Harnessing the energy of the wind is not, of course, a new idea. Throughout history, sailing ships have transported goods and people, opening up new lands and carrying invading armies to distant shores.Windmills, machines that capture the wind’s power to perform a variety of mechanical tasks, were developed later, although the precise time and place of their invention are uncertain. The first references to windmills appear in the writings of medieval Arabs, who described primitive wind machines in Persia in the 7th century A.D. These were apparently developed as early as 200 B.C. and were used to grind grain, a practice that later spread throughout the Middle East. They resembled a merry-go-round with sails and are known as vertical-axis machines, since the sails turn a perpendicular shaft in the center that is attached to a millstone that does the actual grinding. similar devices were developed independently in China and used there at least 2,000 years ago. 

Windmills were introduced in Europe sometime before the twelfth century, apparently by returning crusaders. Although not an indigenous technology, they soon took on an unprecedented importance in medieval Europe, first for grinding grain and later for sawing wood, making paper, and draining water from low-lying farmland. These wooden windmills were horizontal- axis machines, with a drive shaft parallel to the ground and four large blades that could be rotated manually to face the wind. A system of gears connected the spinning shaft to a grinding stone or other device that used the mechanical force. It is this design that evolved into the Dutch version that most people visualize when they think of a windmill.  

By the early 19th century the use of wind power in European industry began to decline. Steam engines run on coal provided an economical substitute for many of the tasks windmills once performed, although in some nations wind’s role continued to grow. Denmark, which largely lacks indigenous fossil fuels, developed improved windmills and used them to supply 1/4 of the country’s industrial energy in 1900. In Australia and North America, pioneers in isolated arid regions found windmills were the only way they could obtain precious irrigation and drinking water.

The bottom line in determining wind power’s potential, however, is the dimensions of the resource. The amount of energy available in the wind is critically dependent on its speed, timing and location. The key to making the wind an all-purpose power source is of course using it to generate electricity. Wind electric generators have been manufactured since the twenties, but because electricity from other sources was cheaper a large market for such turbines never developed.  

Yet the golden age of wind power did not last long. From the twenties onward rural electrification quickly eliminated the need for wind machines in much of the world. The fact that wind machines require relatively little energy to build is a major reason for their economic attractiveness. On the other hand, they don’t give huge amounts of “cheap” power, but they do provide moderate amounts of free, non-polluting, environmentally safe power from an independent source which only costs people whatever they are willing to put into the apparatus for harnessing it.

Fossil Fuels

Coal, petroleum, and natural gas are called fossil fuels.  
Fossil fuel is simply solar energy that has been preserved for millions of years.  Energy from the sun is converted by biological processes into combustible, carbon-rich substances, (like plant and animal tissues).  Usually, organic materials decay, but fossil fuels were buried by sediment and preserved, yielding the coal, oil, and natural gas that we use today.

Coal originated from plant material that once flourished in swamps.  As the lush plants died, they were covered by sand before they completely decomposed. Coal is an important energy resource because there are large reserves of it.  Coalfields in the U.S. can probably sustain our current rate of energy consumption for more that one hundred years.  Some coals contain abundant plant fossils. 

Right now, a little more than 20% of U.S. energy needs are met by using coal.  Coal is mostly used to generate electricity.  Most coal reserves are in the U.S. and Russia.  Coal is probably the dirtiest of all fossil fuels.  Coal can be dangerous to mine.  Many men died of Black Lung because they breathed the coal dust in the mines as they worked.

Strip mining and acid rain are two undesirable side effects of mining and using coal.  Strip mining destroys land value and alters the pH of the soil.  Acid rain can alter the pH of bodies of water, killing the fish and neighboring wildlife.

Coal miners
Also, a large volume of ash is left over after the coal has been burned.  Up to 30% of the original coal volume can be left as ash.