Introduction
Energy History

The discovery of the laws of thermodynamics was extremely important, as our need to understand energy is fueled by the overwhelming use of energy in human society.  From the earliest days, humankind has recognized the need to use energy to condition the environment around it.  Wood was needed to heat homes and to cook food.  Beasts of burden were needed to plow fields and to provide transportation.  When either of these commodities became scarce, hardship prevailed, and solutions were sought.  In ancient Rome, for example, the lack of available firewood led to the passing of laws that made it illegal to build a house or structure that would block another person's home from getting sunlight, as this was the primary method of heating homes without fire.

In the 20th century, fossil fuels (oil in particular) reigned supreme as the energy of choice.  The ubiquitousness of this type of fuel created historically low prices for energy.  This led to a substantial increase in the number of mechanized tools used by the average citizen.  By the year 2000, the U.S. had a population of about 283 million people that were driving over 200 million passenger vehicles.  Almost every home in America has a television, some type of range or stove, and a refrigerator.  About 3/4 of all households have their own washer, dryer, and air conditioner.   Of course, this cheap price does not come without some political and economic consequences.  Energy, and oil in particular, have played a very important role in the economy and politics throughout the last 150 years, affecting everything from the entry of U.S. into World War II to the rampant inflation of the 1970's to the current de-stabilized situation in the Middle East.

Energy Use in the U.S.

This modern dependence on many appliances of convenience requires a lot of energy.  Our current energy per capita use is over 330 million BTU's of energy.  Put another way, this means that the average U.S. citizen would be responsible for using almost 60 barrels of crude oil each year, if all of the energy used in America came from oil.  The only other country in the Western World that was even close to this is Canada, which has almost the same amount of usage.  Most of the Western world uses 200 million BTU's of energy or less.  Although we make up only about 5% of the world's population, we account for almost 25% of all of its energy consumption.  In comparison, many Third World countries such as Ethiopia use less than 1 million BTU's per person.

The majority of this energy (82%) is supplied by fossil fuels.  Crude oil accounts for the largest share of this (38%), followed quickly by coal (22%) and natural gas (22%).  The remaining energy comes mostly from nuclear (8%) and renewable sources like hydroelectric, solar, and wind (7%).  Contrary to common belief, most of this energy is produced domestically.  The only energy source which we are forced to import is crude oil, of which we can currently supply only about 45% of our need.

Of the energy used in the U.S., about 38% of it is used for industrial processes (mining, milling, etc.), 36% of it is used to power homes and offices, and 28% of it is used for transportation.  While most of us cannot directly affect the amount of energy used for industrial processes, we can do something about our residential and transportation energy use. The figures above mean that about 101 million Btu's are used each year just to run our households (this does not include the energy that was lost in producing and transporting this energy, which accounts for an additional 71 million Btu's).  The majority of this energy use is to heat and cool our homes (55%).  In this week's lab, we are going to begin to study ways to reduce our home energy usage, primarily through reducing our demand for heating and cooling.

Further Reading:
" A Look At Residential Energy Consumption in 1997 ", Dept. of Energy, 1999, http://tonto.eia.doe.gov/FTPROOT/consumption/063297.pdf.
 " Annual Energy Review 2000 ", Dept. of Energy, 2000, http://tonto.eia.doe.gov/FTPROOT/multifuel/038400.pdf.