Carbon footprint is defined as the total amount of
greenhouse gases produced to directly and indirectly support human activities,
usually expressed in equivalent tons of carbon dioxide.
According to a U.S.
Environmental Protection Agency (EPA) report, US data centers consumed 61
billion kilowatt-hours of power in 2006. That's 1.5% of all power consumed in
the United States and represents a cost of $4.5 billion. Data centers have been
identified as one of the fastest growing consumers of energy. The EPA is
mandating that government agencies develop strategies for energy efficiency in
government-operated data centers with a target of 20% improvement by 2011 ,
and private sector data centers may soon be asked to meet mandated CO2
limits.
In 2007, data
centers in Western Europe consumed a whopping 56 terawatt-hours (TWh) of power
per year. According to the EU, this figure is likely to almost double to 104
TWh by 2020 . This projected growth, if not offset by innovations in efficient
energy management, will prevent the European Union from achieving its overall
carbon reduction and climate change targets.
Three key factors
affect the carbon footprint of a data center:
1. Location
2. IT load
3. Electrical
efficiency
First key factor:
Location Weather variables such as outdoor temperatures and humidity levels are
an influencing factor on energy consumption. A geographical location which
experiences extreme temperatures and humidity levels will consume more energy
as the data center physical infrastructure systems work harder to maintain
consistent, moderate temperature and humidity levels. The local source of power
generation will also have a major impact on a data center’s carbon footprint. In France, for example, most of utility generated power
comes from nuclear energy. A data center in France would have a much lower
carbon footprint, from a daily operations perspective, than one located in the
Midwestern US. In the case of the US data center, the energy source “mix” may
be 60% coal, 20% oil, 10% natural gas and 5% hydro and 5% wind farms. The data
center in central France would draw 95% of its electricity from a nuclear power
plant. A nuclear reactor does not emit CO2. A coal burning plant does emit
CO2.
Second key factor: IT load reflects how much power the IT equipment in the data center
consumes. The IT load consists of all of the IT hardware components that make
up the IT business architecture: servers, routers, computers, storage devices,
telecommunications equipment, as well as the security systems, fire and
monitoring systems that protect them. Loads can go up (an increase in
processing requirements from the lines of business) or down (impact of virtualiza-tion
or consolidation). The higher the load, the more power will be required to keep
it up and running and the higher the carbon footprint.
Third key factor:
Electrical efficiency Unfortunately, the traditional practice in data centers
of over sizing the physical infrastructure to support the IT load has a very
negative impact overall data center efficiency and therefore impacts carbon
footprint. Data centers are oversized in order to build in a fat margin for
error in terms of estimating data center capacity. Oversizing results in
underutilization of equipment (such as servers that are plugged in 24 hours a
day but that are very rarely used). Fortunately, new generations of modular
scalable IT and physical infrastructure equipment allow for a “pay as you grow”
philosophy that helps to optimize equipment utilization. In addition,
advancements in capacity planning software allow for much more accurate
prediction of data center capacities and of data center power consumption.
Reference:
Data Center’s
Electrical Carbon Footprint by Dennis Bouley
