Earth's Oceans: The World's Next Major Water Resource By Allison Lambert

Water Usage in the U.S. Combined total of 402 billion gallons of water used per day The average person alone uses 50 to 80 gallons per day Various household uses of water include- Showering, toilet flushing, washing clothes, washing dishes, and watering the yard

Current Water Crisis Water Crisis refers to the status of the world’s water resources relative to human demand. The term has been applied to the worldwide water situation by the United Nations and other world organizations. The major aspects of the water crisis are overall scarcity of usable water and water pollution.

Reasons for Current Water Crisis Inadequate access to safe drinking water for about 1.1 billion people Groundwater over-drafting leading to diminished agricultural yields Overuse and pollution of water resources harming biodiversity Regional conflicts over scarce water resources sometimes resulting in warfare

Future Water Crises According to the U.S. government estimates, at least thirty-six states are expected to face water shortages in the next five years. By 2050, it is estimated that some 4 billion people globally will be facing severe water shortages. In the U.S., people living in Southwestern states could be facing severe water shortages even sooner- by 2025.

Possible Solutions A water desalination system using carbon nanotube-based membranes could significantly reduce the cost of purifying water from the ocean. The technology could potentially provide a solution to water shortages both in the United States, where populations are expected to soar in areas with few freshwater sources, and worldwide, where a lack of clean water is a major cause of disease.

Possible Solutions cont. Current price for merely a 10,000 gallon reverse osmosis tank is $66, The new membranes, developed by researchers at Lawrence Livermore National Laboratory (LLNL), could reduce the cost of desalination by 75 percent, compared to reverse osmosis methods used today, the researchers say.

Possible Solutions cont. The carbon nanotubes used by the researchers are sheets of carbon atoms rolled so tightly that only seven water molecules can fit across their diameter. Their small size makes them good candidates for separating molecules. Despite their dimensions, these nanopores allow water to flow at the same rate as pores considerably larger, reducing the amount of pressure needed to force water through, and potentially saving energy and costs compared to reverse osmosis using conventional membranes.

Possible Solutions cont. This special membrane is a porous hydrophobic membrane, which means that water vapor can pass through it, but drops of water cannot. As shown in the diagram on the next slide, by passing hot seawater through one side of the membrane, only the water vapor generated from the seawater passes through. The water vapor is then cooled by the cool water on the other side of the membrane, forming water drops, resulting in freshwater.

Membrane Diagram

The Future of Nanotube Membrane Technology Estimated that these membranes could be brought to market within the next 5 to 10 years In the future, these tubes may go so far as to remove arsenic, fluoride, heavy metals, and toxic organic chemicals. Researchers say that the carbon nanotubes have excellent credentials for water purification.