The article says they are powering it using dedicated transmitters:
“each floor would have one or two RF (radio frequency) power transmitters to power up all switches inside the house.”
It’s confusing because earlier they talk about energy harvesting, which implies “free”. But then they talk about how you will need to run these transmitters, which certainly isn’t free.
I wouldn’t call it “harvesting” if you have operate power transmitters on each floor of the house. “Energy harvesting” usually means you are using something that is already present in the environment.
“each floor would have one or two RF (radio frequency) power transmitters to powe r up all switches inside the house.”