Unfortunately, the FTC does not give Energy Guides for certain appliances, such as portable air condition, clothes dryers, and humidifiers.
This uses 977 watts.
The following equals kWh consumption:
[( 977 watts ) x (Hours used per day) x (Days used per Year)] / 1000
kWh x your electricity rate = cost per year.
(977 watts x 3 hours x 120 days ) / 1000 = 351.72 kWh
351.72 kWh x 14 cents/kWh = $49.24 per year
Here's a 10,000 BTU model which uses 1150 watts: Kenmore 10,000 BTU Portable Air Conditioner