US presidential candidate John McCain has upped the green rhetoric in his fight with Barack Obama, pledging to support “heroic efforts in engineering” to reduce oil dependency.

McCain also used a speech in California yesterday to propose a $300 million prize for battery technology that could succeed current hybrid and electric cars (speech transcript, good coverage in the LA Times).

“This is one dollar for every man, woman and child in the U.S. — a small price to pay for helping to break the back of our oil dependency — and should deliver a power source at 30 percent of the current costs,” he said.

Other proposals from McCain in the speech include $5,000 tax credits for Americans buying zero-emission cars and the conversion of vehicles to use alcohol fuels instead of gas.

“Think of all the highest scientific endeavours of our age — the invention of the silicon chip, the creation of the Internet, the mapping of the human genome,” said McCain in his speech. “In so many cases, you can draw a straight line back to American inventors, and often to the foresighted aid of the United States government.”

McCain’s rival Obama has previously backed government support to domestic auto industry to enable it to produce more fuel-efficient cars (Obama energy plan pdf).

Reuters quotes one of Obama’s economic advisers, Jason Furman, saying McCain “had the chance to make a difference for energy security and America’s families [in Congress]. And he consistently not only didn’t make a difference but has stood in the way of the people like Senator Obama who have been trying to improve our energy security.”

Image: stock photo / John McCain 2008