Carl Nelson from HCW calculated how much power a PlayStation 3 console uses when running the Folding@Home application.
He found out the console uses about 200W:
I am happy to report that the PS3 consumes no more than about 200W while folding, with a Power Factor of 0.99. This is the same peak we saw from it during gameplay. Considering that the PS3 accounts for about 65% of Folding@Home’s current TFLOPS, yet only 13% of the total active processors, this should be considered yet another bragging point for the PS3 as a folding unit.
To give an idea of how much this might cost, my Watts-Up Pro estimates that the PS3 will consume about 138 KiloWatt Hours per month at this rate.
He also provides some figures to give you an idea how much it will cost you to let your PS3 fold 24/7, but this depends a lot on how much you pay for electricity ofcourse:
The price of electricity varies widely around the world, but here in Hong Kong, I pay about $0.12 USD per KWh (after my normal power usage is accounted for). So to keep the PS3 folding 24/7, I will be paying about $16.56 extra on my power bill each month. If I still lived in Vancouver, where they have an abundant amount of hydroelectric power, the cost per KWh is a paltry $0.053 USD. This would mean an extra $7.30 every month to have the PS3 folding 24/7.