BIOFUEL AND BEYOND

In the end, photosynthesis accomplishes two main things. First, it converts light energy from the sun into chemical energy that can be used as food and fuel by plants and animals (including humans). Second, it captures carbon dioxide gas from the air and incorporates those carbon atoms into sugar in a process called carbon fixation. By converting inorganic gaseous carbon into an organic form that can be eaten by animals or used by plants to grow and increase their biomass, carbon fixation is ultimately the way carbon enters the global food and energy chain (see Chapter 22).

Carbon fixation is Jim Sears’s favorite topic these days. Having left Solix in 2007, Sears is now the president of A2BE Carbon Capture, a company based in Boulder, Colorado, that is looking for ways to reduce carbon dioxide levels in the atmosphere. Since plants, algae, and other photosynthetic organisms all help to temper the effects of global warming by pulling carbon dioxide out of the atmosphere and fixing it into organic sugars, scientists are looking for ways to enhance this natural process.

Believe it or not, Sears says, the healthy soil in your backyard is actually photosynthetic. In soil, tiny bacteria called cyanobacteria thrive, and they perform photosynthesis. These cyanobacteria are good not only for the soil but for the entire planet. Like algae, they perform photosynthesis, which means that in addition to absorbing sunlight, they capture carbon from the atmosphere. They then convert the carbon into forms that provide energy and nutrition to colonies of other microorganisms buried deep within the soil. One square meter of healthy, undisturbed soil can remove 30 g of atmospheric carbon per year.

The problem is that approximately 2 billion out of Earth’s 13 billion total hectares of landmass have been damaged by human activity—construction and fires are among the biggest culprits. According to Sears, it can take anywhere from 30 to 3,000 years for soil microorganisms to regenerate after being destroyed—and in the meantime, the damaged soil is unable to remove carbon dioxide from the atmosphere.

Sears, however, has a solution. His new company takes small samples of microorganisms from healthy soil, grows them in a contained facility, and then transplants them to damaged soil, where they spread out and thrive. He estimates that if 1 billion hectares of land were restored in this way, one-seventh of the world’s greenhouse gas problem would be solved because of the vast amounts of carbon dioxide that would be pulled out of the atmosphere by the photosynthetic cyanobacteria in the regenerated soil.

That seemingly simple organisms like algae and cyanobacteria could be so vital to life on Earth is surprising enough—indeed, they provide the planet with much of its breathable oxygen. But soon algae could become the world’s most important fuel source, as well as an ally in the fight against climate change. All this from single-cell organisms that have just one major claim to fame: they can convert the energy of sunlight into energy-rich organic molecules. “Algae truly are the foundations of our entire planet,” says Sears.