Geoff Ballard, the Canadian entrepreneur who transformed pollution-free fuel cells from an exotic power source used in the space program to an everyday engine used in industry, buses and, perhaps soon, in cars, died Aug. 2 in Vancouver, British Columbia, from complications of liver disease. He was 75. In 1999, Time magazine named Ballard a "Hero of the Planet" for his efforts to reduce pollution in cities by getting fuel cells into cars -- an effort that has borne little fruit but that is receiving renewed emphasis because of the rising price of gasoline.

A geophysicist by training, Ballard spent the first years of his career working for the U.S. Army, specializing in hiding fuel tanks for U.S. bombers in Greenland's ice fields.

LOS ANGELES TIMES