Microsoft: Fuel-cell powered data centers cost less, improve reliability
Microsoft: Fuel-cell powered data centers cost less,
improve reliability
Microsoft researchers say fuel cell-based data centers
could go where no data centers have gone before
By Tim Greene, Network World
November 12, 2013 03:46 PM ET
Network World - Data centers powered by fuel cells, not
the public power grid, could cut both capital and operational costs, improve
reliability, pollute less and take up less space, according to Microsoft
researchers.
This technology could make data center expansion possible
in regions where utility-supplied power is tapped out but natural gas is
abundant, according to a paper posted by Microsoft Research. Also, since the
reliability of gas supply is better than that of electrical power, these data
centers would suffer less downtime.
The researchers say there are many variables that need to
be taken into account in engineering these facilities, but overall they hold
potential for greener data centers.
The researchers looked at distributing relatively small
fuel cells – similar to those used on propane-powered buses - around data
centers to power a rack or two of servers each and found several potential
benefits. It eliminates the need for the wired electrical distribution system
in a traditional data center. If a fuel cell were to fail it would affect a
limited number of servers, which data center management software could handle.
Since the power is DC, the AC to DC converters in the servers could be
eliminated.
In that configuration the power supply would be nearby
each rack so there would be no need for a data center-wide electricity
distribution system with its attendant transformers, high-voltage switching
gear and distribution cabling. Pipes to distribute natural gas and leak sensors
cost less. The tradeoff in the amount of space the gear occupies means a 30%
reduction in the required square footage for a data center as a whole, the
researchers say.
The fuel cells emit 49% less carbon dioxide, 68% less
carbon monoxide emissions and 91% less nitrogen oxide, than traditional power methods, the researchers say.
Fuel cells do require specialized equipment that is not
needed in traditional data centers such as reformers that pull hydrogen from
methane, batteries and startup systems and auxiliary circuits.
Design of a fuel cell powered data center would have to
take into account the spikes in server usage that require instantaneous power
supply increases. Fuel cells, which perform best under constant load, can lag
seconds behind changes in demand. “Some of the spikes can be absorbed by the
server power supply with its internal capacitors. But large changes like flash
crowd and hardware failures must be handled by an external energy storage
(batteries or super-caps) or load banks,” the paper says.
The researchers figured use of rack-level power cells at
$3-$5 per Watt, and planned for a five-year replacement cycle for them. The
entire system life was set at 10 years. They eliminated the cost of diesel
generators and uninterruptible power supplies because the natural gas supply is
so reliable. Distribution at the rack level eliminates the need for
transformers, high voltage switching gear and distribution cabling. Pipes to
distribute natural gas and leak sensors cost less. The tradeoff in the amount
of space the gear occupies means a 30% reduction in the required square footage
for a data center as a whole.
This issue could be addressed by installing server-sized
batteries that could jump in with extra power when server hardware is starting
up or shutting down, the times of greatest change in power draw. Fuel cells
give off heat, so these data centers would need greater fan capacity to cool
them.
The capital cost of a traditional data center is $313.43
per rack per month. A rack-level fuel cell data center is between $50.72 and
$63.36 less than that, researchers say. Operating expenses per rack per month
for a traditional data center are $223.51 vs $214.06 for one powered by polymer
electrolyte membrane fuel cells. The savings would be greater with a different
type of technology called a solid oxide fuel cell. Savings would also fluctuate
depending on the price of electricity where the data center is located.
Reliability of natural gas distribution systems is better
than that of the electrical grid, and that would on average cut annual downtime
from 8 hours, 45 minutes to 2 hours, 6 minutes, the researchers say.
The researchers considered using large fuel cells to plug
into a traditional data center design as a direct replacement for a
utility-provided electric service, but they decided that the larger the fuel
cell the greater the chance of failure. Plus the cost was high.
They also considered tiny fuel cells to power individual
servers. A failure would affect just one server, and because the cell is
integrated there is no DC transmission loss. However, lots of tiny cells may
add up to a less efficient and less cost effective use of energy than the
slightly larger ones needed for racks.
Tim Greene covers Microsoft and unified communications
for Network World and writes the Mostly Microsoft blog. Reach him at
tgreene@nww.com and follow him on Twitter@Tim_Greene.
Read more about data center in Network World's Data
Center section.
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