biofuel (n.)

word-forming element, especially in scientific compounds, meaning "life, life and," or "biology, biology and," or "biological, of or pertaining to living organisms or their constituents," from Greek bios "one's life, course or way of living, lifetime" (as opposed to zoe "animal life, organic life"), from PIE root *gwei- "to live."

The correct usage is that in biography, but since c. 1800 in modern science it has been extended to mean "organic life," as zoo-, the better choice, is restricted in modern use to animal, as opposed to plant, life. Both are from the same PIE root. Compare biology.

c. 1200, feuel, feul "fuel, material for burning," also figurative, from Old French foaille "fuel for heating," from Medieval Latin legal term focalia "right to demand material for making fire, right of cutting fuel," from classical Latin focalia "brushwood for fuel," from neuter plural of Latin focalis "pertaining to a hearth," from focus "hearth, fireplace" (see focus (n.)). Figurative use from 1570s. Of food, as fuel for the body, 1876. As "combustible liquid for an internal combustion engine" from 1886. A French derivative is fouailler "woodyard." Fuel-oil is from 1882.