The algae alternative

Another potential new source of energy--one that uses the oldest form of converting the sun's energy into useable fuel;

Isaac Berzin, a 37-year-old chemical engineer, often finds himself mesmerized by algae, as he spends significant stretches of time at his microscope, watching algae cells dance and multiply in reaction to light.

''Photosynthesis," he says. ''That's how all of nature survives. The division time of algae cells is measured in hours. It's very tolerant of everything. You can find it in the Charles River, in sewage, in boiling water, in ice, in Antarctica, in fresh water, in the Dead Sea."

Next week, GreenFuel is taking its systems and ideas out of the laboratory for its first major test drive in the real world. The pilot is set to take place on Vassar Street in Cambridge, on the roof of the MIT Cogeneration Plant, which is the main electrical power plant for the university's central campus. Pending final legal approval by MIT, GreenFuel plans to install a set of about 30 of its bioreactors on top of the plant.

Each of these bioreactors is an eight-foot-high set of clear tubes made of polycarbonate plastic and fashioned into a triangle. Inside the tubes, the emissions from the plant's exhaust will mix with specially designed algae cultures and sunlight. Through natural photosynthesis, the algae will grow in volume while absorbing the carbon dioxide, nitrogen oxides, and other pollutants. The chemical reaction traps the carbon in the algae and gives off oxygen and nitrogen, which by itself is a normal component of air. Finally, the heat from the power plant itself will help dry the algae soup into a flaky coal-like solid that can be recycled and used as fuel in place of natural gas, oil, or coal.