RENEWABLE ENERGY SOURCES
In the 1970s, it was proposed that the world would soon change to a “hydrogen economy” and the first World Hydrogen Conference was held in 1976. Although nuclear energy is well suited to produce hydrogen through the electrolysis of water using electricity or the use of heat to produce hydrogen through chemical reactions, no new power plants have been ordered in the U.S. since 1979. Most of the hydrogen obtained in the U.S. today is produced by the reforming of fossil fuels and releases carbon dioxide as a waste (Lattin, 2007). Hydrogen fuel cells (HFCs) provide great promise in their reduction of carbon dioxide emissions, reduction of air pollutants, and the resulting energy security. Before this promise can be realized and hydrogen vehicles become commercially available, significant technological and infrastructure issues must be addressed (IPCC, Document III, 2007).
About 50 million metric tons of hydrogen are produced in the world annually, most of which is used to make fertilizer and other chemical products. Virtually all of the hydrogen which is produced is used at the sites where it is produced. The majority of the hydrogen is produced through the reaction of methane (from fossil fuels) with water to form carbon dioxide and hydrogen (Lattin, 2007).
Although there are as yet no hydrogen powered vehicles which are commercially available in the U.S., progress is being made. In 2003, there were less than 2 dozen hydrogen fuel cell vehicles in the U.S. and by 2006 there were in 150 in California alone. California has 23 hydrogen filling stations with additional stations planned. In 1998, Chicago implemented hydrogen-fueled buses. Since then, other cities have incorporated hydrogen in their public transportation systems, such as Oakland and Palm Springs (Lattin, 2007).
In 2005, the US Congress passed the Energy Policy Act (PL 109-58), whose requirements included the production of a hydrogen fuel infrastructure by 2020 and an increase in the number of hydrogen vehicles. In the year 2002, each hydrogen vehicle cost at least a million dollars each. Vehicles must store a considerable amount of hydrogen on board (Lattin, 2007).
The costs of hydrogen gas production from solar energy, from natural gas combustion, and as a reactant which can produce methanol from carbon dioxide, are falling sharply (Bockris, 2008). As oil prices continue to rise, an affordable production of hydrogen becomes increasingly likely (Bockris, 2007).
Wind energy generates electricity most efficiently with winds 14-24 mph, which is typical of mountain passes and coastlines. As oil prices rise, countries in regions ranging from
As oil prices rise, countries in regions ranging from
Heat from deep in the earth's surface heats trapped water deposits (180-370 degrees C); pipes may then retrieve this hat water and steam to generate electricity. Geothermal energy production may release pollutants such as hydrogen sulfide, radon, and radium. This energy source is very useful if you live near a deposit. Since deposits are scarce, it cannot be a major energy substitute.
Dams allow rivers to release controlled amounts of water which is then used to generate electricity. Water power provides 21% world's electricity. Hydropower provides virtually all
Wind, geothermal, and water power won't be able to generate energy on a large scale and further development may disrupt pristine natural areas.
Below is a picture of the world’s second largest hydropower plant on the border between
1) Why are nuclei unstable?
2) Types of Radioactivity: Different elements eject different things
from their nucleus.
3) As unstable nuclei eject parts of themselves, they change their identity and eventually become stable atoms. The time it takes for this to occur is measured in half-lives, the time it takes for 1/2 the sample to decompose. Each radioisotope has its own characteristic half life. The half life of the iodine used for medical examinations is 8 days; that of uranium & plutonium is thousands of years (this will become important as we discuss disposal of radioactive waste).
4) Why is radiation dangerous?