How much joules of energy does red light possess?

lights don't contain energy, but batteries do... If you've got an AA battery, it'll be 1.5 volts and have 1 amp hour of juice. That works out to 1.5 watt-hours. 1 joule is a watt-second, so if you multiply 1.5 watt-hours by 60 (minutes in an hour) and then by 60 again (seconds in a minute) you get 5400 joules.