Biofuel research. Ethanol fuel being poured into a beaker behind examples of crops grown to produce it. When produced from crop residues, ethanol is considered a biofuel. It is produced by a process of fermentation. The crops seen here are switchgrass (Panicum virgatum, lower right) and grains of barley (Hordeum vulgare, centre). Growing crops are seen on the screen and reflected on the table. Ethanol is used in motor vehicles as an alternative to fuel obtained from oil deposits. Different plants are being studied to find the ones with the best crop yields. This work is being carried out by the Agricultural Research Service in the USA.