How Can We Save 2-Trillion Gallons of Water?

You'd be surprised how much water...
Jay Egg

Many commercial and residential complexes use cooling towers to effectively aid in cooling.  An average public high school’s* cooling tower uses about 30,000 gallons of fresh water per day when it’s hot outside. That’s enough to fill a good sized back-yard swimming pool. Twice. 

A major airport can consume close to a million gallons of fresh water on a hot summer day, just for cooling tower operations. It’s great that we are honoring watering restrictions, fixing drips in faucets and leaky toilet valves; however there are billions of gallons of fresh water being evaporated and discharged into the sewer from cooling towers every day.

Cooling towers use the process of evaporative cooling to increase the energy efficiency of the air-conditioning equipment that serves the building. In the process, a lot of water is evaporated, and nearly as much more is flushed down the drain to purge out impurities.

The US had about 81 billion square feet of commercial space in 2010, served by 300 million tons of cooling capacity (based on floor space estimates from DOE report). This represents between 5-billion and 15-billion gallons of fresh water consumption each day.

Graphic showing water useage of cooling towers
Buildings + Geothermal = More Fresh Water for US!

Industry has begun to embrace geothermal (elimination of cooling towers) for all the right reasons:

  • Elimination of water consumption associated with cooling towers
  • Elimination of tower related noise
  • Elimination of chemical treatment for cooling towers
  • Reduction in annual maintenance costs for HVAC system
  • Storm proofing through elimination of outdoor equipment (the cooling tower)
  • Impressive federal tax incentives
  • Reduced capital expenditures for regular cooling tower replacement

The advantages that can be cited that make a geothermal sourced building more sustainable are many. With a reduction of water consumption (which can be close to half of all the freshwater consumed by a building), your client is saving money and doing a good thing for the environment.

Cooling towers can be rather noisy, and most will agree that elimination of this outside noise would be of benefit to both the public and occupants of the building.

SW Florida Water Management District Eveporation and Bleedoff Statistics
Geothermal is Renewable and Energy Efficient, Too

Geothermal sourced chiller plants and heat pumps are more efficient by design, because the condenser water is cooler than can be supplied from an evaporative cooling tower, increasing the EER (Energy Efficiency Rating) substantially.

The average life of a chiller is about three decades, and most chiller plants live through two or three cooling tower replacements. With the geothermal source, these expensive planned expenses go away.

By placing a chiller plant, or any cooling tower-sourced building using water source air-conditioners/heat pumps on a geothermal source, you have created an entirely geothermal sourced building, making the entire building’s HVAC system eligible for federal tax credits. This means that when upgrading chillers and water sourced heat pump, they may be eligible for the current tax credits for geothermal systems.

Most regions of the country and the world have storm events periodically such as hurricanes, tornadoes, blizzards, etc. These storm related events can destroy outside equipment. Many insurance companies will provide credits for elimination of this equipment. The New York Times said, “Geothermal Systems Arise as a Storm-Proof Resource.  Additionally, outside equipment often needs to be winterized, and properly installed geothermal sources may save you these seasonal costs and headaches.

The federal government gives a 10% federal tax credit, and five year depreciation through the Maximum Accelerated Cost Reduction System (MACRS) on commercial geothermal systems.  With 50% bonus depreciation the first year, a $1 million upgrade can net federal tax incentives amounting to 48% of the entire cost, or federal tax incentives of $480,000.

Picture of cooling tower
A Helping Hand for the California Drought (and everywhere else)

The USGS says that the average American uses 80 to 100 gallons of water each day.   Cooling towers use as much fresh water as 50,000,000 US residents each day. I think that California could put that water to good use. This is in the neighborhood of 20% of the volume of water that flows over Niagara Falls each day (65 Billion gallons of water flow over Niagara Falls each day).


*based on national average of 752 students per high school, 2000