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Putting Plants to Work Using the power of the sun is nothing new. People have had solar-powered calculators and buildings with solar panels for decades. But plants are the real experts: Theyve been using sunlight as an energy source for billions of years. Cells in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into sugars and starches, stored energy that the plants can use. This conversion process is called photosynthesis. Unfortunately, unless youre a plant, its difficult and expensive to convert sunlight into storable energy. Thats why scientists are taking a closer look at exactly how plants do it. Some scientists are trying to get plants, or biological cells that act like plants, to work as miniature photosynthetic power stations. For example, Maria Ghirardi of the National Renewable Energy Laboratory in Golden, Colo. , is working with green algae. Shes trying to trick them into producing hydrogen instead of sugars when they perform photosynthesis. Once the researchers can get the algae working efficiently, the hydrogen that they produce could be used to power fuel cells in cars or to generate electricity. The algae are grown in narrow-necked glass bottles to produce hydrogen in the lab. During photosynthesis, plants normally make sugars or starches. But under certain conditions, a lot of algae are able to use the sunlight energy not to store starch, but to make hydrogen. Ghirardi says. For example, algae will produce hydrogen in an airfree environment. Its the oxygen in the air that prevents algae from making hydrogen most of the time. | 
