&gt; Vaguely imagining a completely unpowered electronic lock, and a handheld &#x27;key&#x27; that I guess would contain a fairly beefy battery<p>That&#x27;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&#x27;d think.<p>It&#x27;d be even cooler if cell phones could <i>transmit</i> power wirelessly, but AFAIK phones with inductive charging hardware can only receive. If they added the ability to transmit, suddenly your phone&#x27;s battery could become a sort of universal power source for talking to various passive devices like locks and stuff.<p>Though, this is slightly different from what&#x27;s described in the article. If I&#x27;m understanding it correctly, this thing is harvesting its power from a standard RFID signal, so you don&#x27;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.