In most cases, a tower fan will use more energy than an air cooler. A tower fan can use anywhere from 50 to 150 watts while an air cooler can use up to 500 watts. That means that a tower fan will typically use about three times as much energy as an air cooler. However, some tower fans are designed to be very energy efficient and may only use around 10 or 20 watts of power. So, in some cases, a tower fan may actually be cheaper to run than an air cooler.