Also relevant, houses aren't boiling a kettle and running their oven 24x7, so this is more like worst-case peak load and will be spread across different houses. Having some kind of battery storage closer to the houses will help a lot - the tidal generator can run fairly constantly and fill the battery, and the houses can draw in short bursts from the battery.
Yeah. I always feel that the solution for clean and abundant energy globally is to start with better energy grid management (and storage). There's already so many fit-to-all-geography solutions available. It's just that current grid is used to supporting lines centralized around big energy plants and not small producers.
I also always feel that there's a lot more to take down from energy consumption per household by simply making more efficient devices (especially for heating and cooling). It's possible that modern AC/heaters are already close to the peak electrical efficiency, but I guess even better producer standards for things like insulation, thermal conductors or precision sensors could still squeeze something out of the nation-wide usage.
