Al Gore, 17 July 2008: “Today I challenge our nation to commit to producing 100 percent of our electricity from renewable energy and truly clean carbon-free sources within 10 years. This goal is achievable, affordable and transformative. It represents a challenge to all Americans - in every walk of life: to our political leaders, entrepreneurs, innovators, engineers, and to every citizen. A few years ago, it would not have been possible to issue such a challenge. But here's what's changed: the sharp cost reductions now beginning to take place in solar, wind, and geothermal power - coupled with the recent dramatic price increases for oil and coal - have radically changed the economics of energy… We are on the eve of a presidential election. We are in the midst of an international climate treaty process that will conclude its work before the end of the first year of the new president's term. It is a great error to say that the United States must wait for others to join us in this matter. In fact, we must move first, because that is the key to getting others to follow; and because moving first is in our own national interest. So I ask you to join with me to call on every candidate, at every level, to accept this challenge - for America to be running on 100 percent zero-carbon electricity in 10 years. It's time for us to move beyond empty rhetoric. We need to act now.” .
. Al Gore, “Green energy by 2018”, 17 July 2008 speech; reported in “Al Gore: A generational challenge to repower America”, We can solve the climate crisis: http://www.wecansolveit.org/pages/al_gore_a_generational_challenge_to_repower_america/ ; see also Bobbie Johnson, “Gore urges US to try for 100% renewable energy within a decade”, UK, Guardian, November 2008: http://www.guardian.co.uk/environment/2008/nov/10/renewable-energy-alternative-energy .