Best Clean Energy Innovation Engine Is a Hybrid?

Intriguing new policy brief argues that the "green innovation machine" will be less than optimal (read: will not curb climate change) if it relies only on a carbon price-setting mechanism like cap-and-trade.  The authors recommend supplementing with an aggressive program of "directed technological change" through significantly ramped up clean energy R & D subsidies implemented immediately.  And they believe they have the economic proof to back up their claims.