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.
I updated the title.