First, this claim is based on a discredited supply side economics view of invention. Just because there is an economic incentive to invent something, doesn't mean that inventing it is technically or physically possible, or even if it is invented, that other barriers to deployment won't arise. An analogy should make the point clear: vast economic incentives exist to invent pills that would cure alcoholism or drug addiction, and indeed much snake oil gets peddled claiming to provide such benefits. You may have noticed, however, that substance abuse doesn't seem to have disappeared from our society. Given the addiction of modern civilization to cheap energy, the parallel ought to be unnerving to anyone who believes that technology will pull our the climate rabbit out of the fossil fuel hat.
Second, the hopes that many greens place in a technological deus ex machina is an expression of faith in the old high modernist verities every bit as profound - and every bit as rational - as Augustine's faith in Christ. Very telling in this respect is the totemic way in which the Manhattan Project, the ultimate high modernist technological triumph, is regularly invoked as a supposed model for developing breakthrough Green technologies, despite the radical differences between building a weapon and remaking the entire global energy system. In truth, the belief in a technological fix to the climate solution is the ultimate form of high modernist magical thinking. It's no coincidence that the phrase "technological fix" was invented in the early 1960s, the heyday of modernization theory, by Alvin Weinberg, a nuclear physicist and chief administrator at Oak Ridge National Laboratory from the Manhattan Project period through the 1980s. (See Weinberg's essay "Can Technology Replace Social Engineering?" .) Weinberg claimed that nuclear power would create limitless energy, allowing age-old social problems to be overcome while minimizing political conflict over distributional issues - an argument that should feel uncannily familiar to all those who believe that technological breakthroughs will allow the climate crisis to be overcome without fundamental political conflict.
Update: Here's Steve Chu artfully backpedaling from the idea of a green Manhattan Project.