Perma-Energize?

Since Energize recharges in 120 seconds and lasts 30 seconds, perma-Energize would require 300% +rech to be perma (319%, if you want to be truly perma insofar as having the buff reactivate as soon as it drops thanks to the 1.32 sec animation time). Lightning Reflexes provides you with an extra 20% +rech and basic slotting would provide you with ~95%. This would leave you needing 185% (205%) more +rech. Hasten would provide 70% (Hasten only requires 375% +rech to be perma so it's perfectly fine to assume perma-Hasten before perma-Energize) so you'd need to grab 115% +rech from set bonuses and IOs in order for it to be permanent.

Keep in mind, however, that the duration effects of Energize aren't really the most beneficial parts of the power. The initial heal will provide more hit points than the regeneration ever will (it would require 100% +maxhp in order to equal the initial heal's contribution; the max for Tankers is only 71.4% +maxhp) and, considering that you should already packing Power Sink, the end redux isn't really all that great either. It's still of the utmost importance to get it recharging as quickly as possible so you can benefit from the heal as much as possible, but you still shouldn't view Energize as a power that needs to me made perma. If anything, it benefits more from the fact that you're getting that nice big heal every 30 seconds more than the fact that you're getting to benefit from the buff at all times.