Our environment is the most important resource that we have and one that we have often taken for granted. One of the environmental concerns facing the world today is the possibility of global warming resulting from a build-up of what are called greenhouse gases, some of which occur naturally. As the sun heats the earth’s surface, the earth radiates energy back into space. Atmospheric greenhouse gases trap some of this outgoing energy and retain heat. The natural greenhouse effect keeps temperatures on the earth mild enough to sustain life. However, according to the National Academy of Sciences, the Earth's surface temperature has risen by about 1 degree Fahrenheit in the past century, and this warming has accelerated during the past twenty years. There is strong evidence that most of the warming over the last 50 years is caused by the build up of greenhouse gases – mostly carbon dioxide, methane, and nitrous oxide. Why is this happening? Most scientists believe that the increased use of fossil fuels to run cars and trucks, heat/cool homes, operate industry businesses, and power factories is the primary reason.

In June 2005, the U.S. National Academy of Sciences joined similar groups from nations around the world in recognition of the potential dangers ahead. They issued a call for action to reduce greenhouse gas emissions.

Can nanotechnology help us address this challenge?

Renewable Energy

It is estimated that approximately 85% of the energy needs in the U.S. are met by fossil fuels (coal, oil, and natural gas). These are also known as unrenewable energy sources, meaning there is a limited supply that cannot be replenished. Renewable energy sources on the other hand are constantly replenished. Most renewable energy comes from the sun either directly (i.e., solar energy) or indirectly (i.e., wind power which is controlled by the sun).

Renewable energy technologies are often referred to as clean energy since they are far less harmful to the environment than conventional energy sources. Nanotechnology is offering a range of new opportunities. For example, nanotech researchers are working on the development of a solar panel/fuel cell combination. The idea behind the technology is that when the solar panel is producing energy, the fuel cell is running in reverse to collect excess energy, convert it to hydrogen, and store it. When the sun goes down and the solar panel is no longer producing energy, the fuel cell will run forward and produce energy from the hydrogen it has stored.

Remediation - Cleaning Up

During the Cold War period, the U.S. created a vast nuclear weapon research, development, and testing infrastructure. The result of this extensive activity is that approximately 7,000 sites across the country have subsurface contamination. The Department of Energy estimates that this includes groundwater equal to 4 times the U.S. daily water consumption, and enough soil to fill 17 professional football stadiums. With current technology, cleaning up this problem could take 70 years at a cost of $300 billion dollars.

Nanotechnology could provide cost-effective solutions to this and other challenging environmental cleanup problems. Researchers are currently experimenting with nanoparticles that have the ability to detoxify a wide variety of common contaminants. In one study at the University of Florida, researchers are using nanotechnology to develop composite materials that can sense mercury vapor in the air and absorb it. They have also shown that the nano-composite material will release the absorbed mercury when exposed to a heat or vacuum treatment, providing recycling opportunities.

(Zhang, W., J. Nanoparticle Research, 5, 323-332, 200).