data centers

"Data Center" is often a generic term used to describe a number of different types of facilities that house digital electronic equipment for Internet site hosting, electronic storage & transfer, credit card & financial transaction processing, telecommunications, and other activities that support the growing electronic information-based economy.⁽¹⁾ A few common terms & client profiles for data centers are:

Data Storage & Internet Hosting Facilities, also known as server farms or Internet hotels, which perform a variety of functions.
Internet Service Providers (ISPs) are dedicated specifically to supporting the Internet.
Telecommunication Switches, known as telecoms or telcos. These are more energy demanding than typical Internet data centers.
Corporate Data Centers, where racks and computer equipment are wholly owned and operated by the corporation. Energy demand may be better characterized at these facilities since only one entity owns & operates them.
Managed Data Centers, where racks and computer equipment are owned by the data center owner but leased to tenants.
Co-Located Server Hosting Facilities, also known as CoLos, where rack space is leased by tenants and computer equipment is owned and operated by tenants. Energy demands for this type of facility tend to have greater fluctuations and to be less-well characterized than corporate data centers.

Geographic Locations of U.S Data Centers

Data centers are generally concentrated in cities with major fiber optic nodes. As indicated in the map below, the Gulf Coast Region contains five primary nodes. These nodes are located in Austin, San Antonio, Dallas, Houston, and New Orleans.⁽²⁾

Data centers house a high density of digital electronics and computer technology requiring higher quality and more reliable electric power than most commercial buildings. These facilities range in size from a

small computer room housing a few server racks to 200,000 square feet or greater dedicated facilities holding tens to hundreds of server racks.⁽¹⁾

The computers used in data centers are generally known as servers. Multiple servers are secured in racks that typically have a 2-foot by 2.5-foot footprint and are 70 to 87 inches high. These racks are placed on raised floor area, which serves as a plenum allowing cooled air to move below the racks, then up through perforated floor tiles to cool the racks before being drawn back through the HVAC system.⁽¹⁾

Approximate Usage of Total Building Floor Space for a Dedicated Data Center

Area	Usage (%)
Core and common area (halls, stairways, elevators, electrical & mechanical space)	20 - 25%
Generators, batteries, power supply, conditioning equipment)	25 - 30%
Raised Floor Area	50 - 60%

Power in data centers is divided between powering the servers and the much larger need for quality HVAC. Today's servers generate heat by switched mode power supplies, which are very powerful and emit a substantial amount of heat. HVAC has been projected to range from 40-60% of the electric load in data centers.⁽²⁾

These facilities operate 24/7 and require 99.9999% reliable power at a 50 ms level. They aim for 99% reliability from the grid, 99.99% from the addition of standby diesel generation sets, and 99.9999% by adding UPSs (uninterruptible power sources) on each server.⁽²⁾

Data centers in the United States now consume an estimated 20 to 30 billion kilowatt-hours of electricity annually, roughly equal to the electricity consumption of Utah. ⁽³⁾

Why is CHP Attractive for Data Centers? ⁽⁴⁾

The realities in server, telecom, and data facilities are these:

The equipment being operated within these facilities are significantly more expensive than the construction costs of the building itself.
Customers usually pay for service as it is received, whether from user access fees or direct on-line time fees. Continuous operation means continuous revenue production.

Internet, telephone, and data customers have an extremely high expectation of reliability and a growing desire for speed, as witnessed by the recent growth in broadband service.

The need for uninterrupted service is very great, and the industry has gone to great lengths to attempt to achieve it. Data centers often request that electric utilities run 2 or more separate feed lines to improve reliability and lower the chance of power interruption. Power quality is ensured with extensive power conditioning equipment, with back-up power systems including batteries, flywheel storage, ultra-capacitors, and on-site power such as diesel generators ensuring supply in case of a power failure. In addition many data centers have multiple redundancies built into their power and HVAC systems to ensure that power & thermal management are maintained at all times.

Additionally, the internal power and HVAC loads for these facilities are unique, including such issues as:

Intense electrical loads per square foot
Intense cooling loads per square foot
Need for continuous power during grid power failures
Need for continuous cooling during grid power failures
Need for continuous electrical voltage support with no fluctuations

Combined heat and power (CHP) technologies may offer a reliable, energy efficient alternative for providing data centers with high-quality power. CHP systems are highly efficient, reliable and offer flexibility in fuel selection. Modeling analysis has demonstrated significant air emissions, transmission and price benefits of clean CHP technologies.

Case Studies

ChevronTexaco Corporate Data Center - San Ramon, CA (222 KB)
This system uses one 200 kW phosphoric acid fuel cell fueled by natural gas

Publications

The Role of Distributed Generation and Combined Heat and Power (CHP) Systems in Data Centers (633 KB)
U.S Environmental Protection Agency, CHP Partnership, August 2007

References

1 - Energy Smart Data Centers: Applying Energy Efficient Design and Technology to the Digital Information Sector (871 KB)
Beck, Fred; REPP, November 2001

2 - An ACEEE White Paper: Overview of Data Centers and Their Implications for Energy Demand (402 KB)
Brown, Elizabeth et al; ACEEE, September 2001

3 - Energy Efficiency in Data Centers: A New Policy Frontier (100 KB)
Alliance to Save Energy; ASE, January 2007

4 - Targeted CHP Outreach in Selected Sectors of the Commercial Market (3.39 MB)
Ryan, William; The University of Illinois at Chicago Energy Resources Center, 2004

5 - Target Market Workshop Presentations from 7 Sep 2011 Workshop on DG/CHP for Secure Power, Irvine, CA

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