> Vaguely imagining a completely unpowered electronic lock, and a handheld 'key' that I guess would contain a fairly beefy battery

That's a good idea, actually. I dunno about this technology specifically, but there are wireless power standards that can transmit more power, e.g. Qi can provide 5W at a up to 4cm according to Wikipedia. That should be plenty suitable for a lock I'd think.

It'd be even cooler if cell phones could transmit power wirelessly, but AFAIK phones with inductive charging hardware can only receive. If they added the ability to transmit, suddenly your phone's battery could become a sort of universal power source for talking to various passive devices like locks and stuff.

Though, this is slightly different from what's described in the article. If I'm understanding it correctly, this thing is harvesting its power from a standard RFID signal, so you don't need any special power transmission hardware. No way would you be able to get enough power out of it to power any kind of mechanical actuator for a lock.

Instead of battery, you could turn the key inside a mechanism that would produce the energy needed to open the lock ;-)

True, but an electronic lock has lots of advantages over a mechanical one. Especially for a business, you can trivially grant and revoke keys as well as track access. I feel like in principle they could be more secure too as all but the fanciest of locks are pretty trivial to pick, though that's predicated on somebody building an electronic lock without hardware/software/cryptographic flaws (good luck).

We looked into this for a while for some of our products and even filed some ip (such a waste of time). We were doing it with thermopiles on our vents and using a buck and boost. It worked for heating well, maybe well enough for cooling, but was price prohibitive (would up retail 50% at least). https://flair.co

The lock-powered-by-key exists: http://www.cyberlock.com/access-control/cyberkey-smart-keys . The power and signaling go through metal contacts rather than wirelessly.