Before considering some of the more popular forms of renewable energy, I would like to include information on the late Richard Smalley's idea of the "Terawatt Challenge". Smalley was a Noble Prize winner who famously listed the ten most important problems that the world would have to confront in the near future. A safe and cheap form of energy was near the top of the list. Smalley suggested that in the future, for all world citizens to have enough energy to live a comfortable life, we would need to significantly increase the daily amount of energy. Smalley proposed that there be an effort made to increase the daily world energy production from 15TW produced in 2005 to 60TW by the year 2100.
Since, not only students, but most adults have a difficult time understanding large numbers, I feel it would be worthwhile for students to pictorially show these amounts as a way of making them somewhat appreciate the size of what we are speaking.
Activity 2: Picturing Our Energy Needs in Dots
There is a web site called A View from the Back of the Envelope
, which contains a number of math resources. Among its resources, I found a representation of 10,000 dots in a square no more than 2 inches squared. I chose to use the graphic in this activity. I have seen students do pictorial representations of smaller amounts and the satisfaction they feel as they complete the task is well worth the time.
Material: copies of the 10,000 dot square, scissors, two large sheets of paper or poster board, and glue
1. Students cut out and pasted 200 squares and glued 100 on each of two large sheets of paper.
2. We then put in between the following label: 1,000,000 X 1,000,000 = 1,000, 000,000,000 (one million times one million equals one trillion). One trillion is the number of watts in a terawatt.
3. I suggest covering the walls in the halls outside your room with the representation, as it would be a valuable activity, and of interest to other classes and teachers. Students need to know that 15 times this representation would show the number of terawatts the world uses of energy. What Smalley is suggesting is that we will need over five times that much energy by the year 2100.
Students should know that our concern about our energy needs is not a new problem, and many would say we have been reluctant to change our dependency on fossil fuels.
The history of the use of fossil fuels is a long one. In ancient times the primary source of energy was the burning of wood. Until about 300 to 400 years ago there seemed to be a balance between what was cut down and the regrowth of the forests. In places like England the deforestation became a larger problem as the Industrial Revolution began. Coal began to replace wood as the fuel of choice. It was used to run the railroads, make steel, and burn in homes after chimneys became fixtures in home design. In England where the Industrial Revolution was centered, coal was abundant and promised a source of fuel that did not depend on the rest of the world. Even then, coal had a reputation for being a dirty energy source, and the smell and dust from coal was recognized as a potential health hazard. Ironically, coal is now being consumed at a greater amount than ever. In 2005 coal was 27.8 percent of the world's energy.
Coal does have its advantages over other fuels. It is one energy source whose reserves are measured in hundreds of years. Coal is safe because it does not explode like natural gas. It is the cheapest source of nonrenewable energy and there is no potential environmental danger as there is with an oil spill. Most coal producing countries do not have to rely on other nations for their supply, so it is a secure energy source. Finally, it can be clean burning with scrubbers to remove impurities such as sulfur, although there are greater carbon dioxide emissions than with oil or natural gas and also production of ash that can cause environmental problems for disposal.
One of the early fuels used for lighting lamps was whale oil. For years, the whaling industry thrived and threatened the future of these animals. As their population decreased, the cost of whale oil rose. Oil was not an unknown product. Centuries ago people like the Egyptians used the tar they found at the surface of the land for the process of mummification. It was long understood that anyone who could find an abundant source of oil would become immensely rich.
In 1859, a large oil deposit was found in Titusville Pennsylvania by Edwin Drake. Kerosene was a bi-product of crude oil that could be used for illumination. With the discovery of a large source of oil in the United States, kerosene gradually surpassed the use of whale oil. As oil deposits were found around the world, the real work of developers like Rockefeller was to find ways to bring oil to markets around the world and make it economically the fuel of choice. In fact, at first gasoline was burned off because it was seen as having little value. With the development of the automobile in the 1920's, gasoline was found to be just the correct fuel for the car engine.
Natural gas is also a product that was utilized for centuries. The Chinese were known to have used bamboo piping to transport gas to where it could be use as a heat source. Natural gas is mostly methane. It is the cleanest of all the fossil fuels with water and carbon dioxide as bi-products when it is burned. On the positive side, gas needs little processing before it can be used by consumers. However, gas can be explosive and asphyxiate people if there are leaks. Another problem is that transporting gas from its origin to the marketplace can be a challenge. Construction of pipelines is expensive and sometimes the terrain makes it next to impossible to harvest the gas. There is also the problem of protecting pipelines from sabotage.
There have been attempts to solve the problem, but as they shall see, there is not one easy answer. Each new technology has its limitations. As we actually begin considering some of the more popular forms of renewable energy, one of the aims should be to give the pros and cons of each form of potential energy.