I think your math is off by a bit. A Calorie and a watt-hour are approximately equal. Humans need about 2000 Calories per day. So 2.9 watt-hours is more like th

I think your math is off by a bit. A Calorie and a watt-hour are approximately equal. Humans need about 2000 Calories per day. So 2.9 watt-hours is more like the amount of energy a human needs in a minute. I think the confusion might come from the Calorie/calorie difference, i.e. 1 Calorie = 1000 calories = 1 kcal.