Unrefined algae oil is also known as &39'green crude&39'.

The U.S. has enough land in the right climate to produce homegrown algae oil that would replace a significant amount of foreign oil imported for transportation use--without endangering its water supply.

The Gulf Coast region, the Southeastern seaboard, and the Great Lakes areas are ideally suited to grow algae in outdoor freshwater ponds with minimal water usage.

That's according to a study released today by the Department of Energy's Pacific Northwest National Laboratory (PNNL) in the journal Water Resources Research.

Biofuel made from refined algae oils, while showing promise, is still in the early stages of development. In addition to the usual scalability questions put to the developers of any new technology, algae developers have been under even closer scrutiny because a lot of water is required to grow it.

The PNNL says its study is the first comprehensive land-use and water-use assessment of a potential algae oil industry in the U.S.

PNNL researchers found that if you compare algae and corn hectare to hectare, algae grown in outdoor ponds annually produces 80 times more oil than corn. Theoretically, they said, the U.S. has enough available land to produce "48 percent of the current transportation oil imports" with algae. However, that level of production across the U.S. would require too much water--an average of 350 gallons of water to grow and produce one gallon of algae oil.

Raceway algae ponds in Southern California.

Instead, the PNNL researchers, led by hydrologist Mark Wigmosta, recommend producing algae only in regions of the country with both the right land and high humidity. They found that if algae are grown in a climate already high in humidity, much less water is needed. The group also identified the regions mentioned above as the best places to grow it.

This would still give the U.S. the ability to produce 21 billion gallons of algal oil a year' roughly 17 percent of the amount of oil that was imported for transportation in 2008.

The study involved the creation of a massive database that used 30 years of meteorological data and comprehensive geological surveys of the U.S. in addition to algae oil research data. Mathematical modeling of algae growth rates, and processing, drew on that database for its outcome.

"That database contained information spaced every 100 feet throughout the U.S., which is a much more detailed view than previous research. This data allowed them to identify available areas that are better suited for algae growth, such as those with flat land that isn't used for farming and isn't near cities or environmentally sensitive areas like wetlands or national parks," the PNNL said in a statement.

The study concentrated on freshwater algae. The PNNL researchers of the study announced that there next project is a comprehensive study on the feasibility of using salt water and waste water to grow algae.