How to find the power dissapation of a resistor
Grey-brown-brown-gold indicates an 810 ohm 5% resistor. 

I = V/R = 24/810 = ~30mA

P = IV = 30mA * 24 = 720mW

It looks like it's a 1W resistor. 

Edit: It could possibly be a 910 ohm resistor (white-brown-brown) which is part of the E24 set of values. It would still need to be a 1W resistor.