Sweet sorghum is grown in the U.S. for cooking and as livestock feed. But the tall plant also has a

juicier benefit.

A sugary sap inside the plant's stalk, which can grow as tall as 12 feet, can be turned into a potent biofuel. So experts and companies are studying its potential with hopes that farmers will want to plant more of it.

Ethanol made from the stalk's juice has four times the energy yield of the corn-based ethanol, which is already in the marketplace unlike sweet sorghum. It produces about eight units of energy for every unit of energy used in its production. That's about the same as sugarcane but four times more than for corn.