Iron Mountain Data Centers: Geothermal Cooling System

BACKGROUND

Iron Mountain Data Centers' Boyers, Pennsylvania site is located 200 feet underground in a former limestone mine containing a 35-acre water reservoir. The decision to build the data center near this part of the mine was based on the year-round low ambient temperature and the location of the lake for geothermal cooling.

The team at Iron Mountain Data Centers developed an innovative energy-efficient cooling system that enables customers to enjoy the benefits of reduced energy consumption, increased reliability, and improved security.

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SOLUTIONS

The geothermal cooling mechanism consists of an underground reservoir and a supplementary surface-mounted free-cooling chiller plant. The reservoir is a low-humidity space with consistent water level and temperature year-round. The cooling mechanism has three major design components – reservoir pumps, heat exchangers, and building loop data center pumps – all of which are repeated for capacity and redundancy to meet Tier 3 Data Center Design Standards. The pump works by lifting the water into a heat exchanger where it receives the heat from the data center and rejects it when the warm water from the heat exchanger returns to the reservoir.

The cooling system was commissioned in 2013, added more capacity in 2015, and incorporated the surface-mounted chiller plant in 2018. The addition of the high-efficiency chiller plant served two purposes: another layer of reliability, and increased energy efficiency during the winter months by bringing in supplementary, pre-conditioned outside air.

In addition to the efficient design, the Iron Mountain team continued to look for and implement optimization strategies for additional energy savings opportunities. The team recently found almost 14% additional savings through load shifting and system tuning several years after initial construction.

These ongoing efforts, combined with the innovative cooling system, result in a cost-effective, low power usage effectiveness (PUE), benefitting both the environment and customers.

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OTHER BENEFITS

The reservoir also provides a key reliability component many data center operators look for: backup thermal storage. Most sites strive for mere minutes of chilled water storage onsite for cooling during a chiller plant failure, whereas the Boyers site has an unlimited run time of cool water and redundant pumps to maintain cooling. Additionally, the simple variable flow pump design with very few moving parts provides increased reliability and lower maintenance costs by reducing mechanical complexity.

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Annual Energy Use

(Source PUE)
Baseline (2016)
1.9 PUE
Actual (2019)
1.6 PUE

Energy Savings:

34%

Sector Type

Commercial, Data Centers

Location

Pennsylvania

Project Size

35 Acre Reservoir

Boyers Data Center - Cave
Boyers Data Center - Cave

Boyers Data Center - Entrance
Boyers Data Center - Entrance

Boyers Data Center - Interior
Boyers Data Center - Interior

Boyers Data Center - Server
Boyers Data Center - Server