Aquifer Thermal Energy Storage - ATES

Energy Studies

Aquifer Thermal Energy Storage Photo

Have you ever wished, on a hot summer day, that you could have some of last winter’s ice and snow to cool your beverages or your sweaty brow?

 Many energy problems result from not having what we need (warmth or coolness) at the right place and the right time. ENERGY STORAGE is a fast growing field with applications ranging from batteries (which store electricity) to pumped storage (pumping water uphill when electricity is cheap and then releasing the water to generate electricity when demand and price are high).

 ENERGY STORAGE is considered a conservation measure. It has the same positive impact as use of renewable energy technologies.

 Stockton’s ATES system is a SEASONAL COLD STORAGE facility. It is SEASONAL because it stores energy from winter to summer. Some systems, like the pumped storage described above, operate on a daily cycle and others, like batteries, store energy indefinitely. It is COLD because chilled water is what is stored, and cold for air conditioning is what Stockton needs. (Stockton’s heating needs are met by the Geothermal System and conventional boilers.)

 AQUIFER THERMAL ENERGY STORAGE systems store winter’s natural cold by chilling groundwater and putting it back into the aquifer for storage. Groundwater is chilled by being run through a cooling tower when conditions of temperature and humidity are favorable.

 In summer, the chilled water is withdrawn, used for air conditioning and put back into the aquifer.

 The LAYOUT – Stockton’s ATES system consists of six large wells and associated piping, pumps and cooling tower. The wells, with their pumps, are located in two clusters, about 950 feet apart. One cluster is located near the West Quad Building and the other near Lot 1. The cooling tower is located at the Manifold House, which is alongside of Lot 1. The ATES piping is connected to the campus cooling loop, which connects five buildings in the main academic complex.

 Q & A

 What impact does ATES have on quality of groundwater?

 HEAT EXCHANGERS are used to protect groundwater from exposure to contaminants or unfavorable conditions. The system is designed to prevent exposure of the groundwater to the atmosphere because naturally occurring dissolved gases would be released from the groundwater. The only change to the groundwater is in its temperature, which is lowered to 41 degrees F.

 What about quantity of groundwater?

 ATES does not consume any groundwater. All the water that is withdrawn is returned to the same aquifer.

 Why doesn’t the chilled water go away between winter and summer?

 Water in the Cohansey aquifer moves very, very slowly, so at least 90% of the cold can be recovered. The aquifer was carefully evaluated to determine its suitability for this project.

 What permits and approvals were required for this project?

This project was carefully reviewed by the NJ Department of Environmental Protection (Bureau of Water Allocation), the NJ Pinelands Commission and the NJ Department of Community Affairs.

 What was involved in drilling such big wells?

The same technology used for household wells can be scaled up for larger wells. Gravel was packed around the lower 70 feet of screen on each well. The wells were “developed” through pumping and agitation to ensure an adequate flow of very clear water.

 Why do the signs refer to ATES as a “research laboratory”?

Because this is too good an opportunity to miss! Stockton students and faculty will be evaluating the system in detail. Meters and other instruments were added to the project to facilitate analysis of energy savings. Our goal is to collect data so other institutions can plan a similar system with the confidence of knowing what the benefits will be.

 If this is a good system, why haven’t I heard of it before?

Energy conservation measures are less “glamorous” than renewables like solar or wind power. In Europe, where energy prices have been higher than ours for years, ATES systems are in use at 200 or more locations. Because of the need for a certain type of aquifer, not all locations in Europe or the US are suitable for ATES.

Could I have a system like Stockton’s at home?

No. At home you need both heating and air conditioning (in roughly equal amounts). You can install a geothermal system.

Links to related information pending.