A 10,000 mAh power bank is able to run 10 validators (including Geth + Rocket Pool) on a Raspberry Pi for 10 hours.
The Pi consumes 5 watts, so that comes to around 0.1 KWh’s of energy per day for 10 validators, or 0.01KWh per validator.
That 3600x more energy efficient than Bitcoin PoW, or, put another way, a 99.97% reduction in power.
probably not, especially compared to the 8% apy you will get from validating. After the merge (pure pos) apy will be higher (10-12%). Validating at home is not to hard to setup as well, you can do it on a raspberry-pi as in the article (though its recommend to have beefier hardware)