One of the challenges of tidal wave energy is: the start-up costs are expensive. the materials needed to couple the tidal energy to electricity are rare. the tides are very unpredictable. as global warming increases, the tides will diminish.

Air conditioners not only cool air, but dry it as well. suppose that a room in a home measures 5.0m×9.0m×2.4m . if the outdoor temperature is 30 ∘c and the vapor pressure of water in the air is 85 % of the vapor pressure of water at this temperature, what mass of water must be removed from the air each time the volume of air in the room is cycled through the air conditioner? the vapor pressure for water at 30 ∘c is 31.8 torr.