Page 39 - Energize December 2022

TECHNICAL

Server level FC power capital cost for state-of-the-art data centres. In addition, in many
It is possible to integrate small FCs that only produce a few geographical regions, the energy-equivalent gas price is lower
hundred watts of power into the server itself. This option than electricity price, even after accounting for FC conversion
eliminates even the short distance power cabling from the efficiency. FCs do not have moving parts and can be easier to
rack level FC to servers, minimising DC transmission losses. The maintain than diesel generators. 3
reliability is also maximised, as FC failures only affect a single
server. However, smaller FCs may not be as energy efficient and Field experience
cost effective as their larger counterparts. At the server level, one Microsoft and a Californian university have managed to power
cannot take advantage of statistical multiplexing across multiple a 12 kW rack of servers by a fuel cell installed in the rack itself,
servers to smooth the load. eliminating electrical infrastructure equipment and demonstrating
In terms of redesign, it is expected that a data centre a dramatic improvement in energy efficiency.
would need to commit totally to fuel cells to realize cost The pilot consisted of a 10 kW PEMFC stack and 2,5 kW
savings. Some factors that would affect this include placing the SOFC stack and system as the distributed DC power source.
7
distributed fuel cells near the load but in vertical configurations This demonstrated a direct generation method that places fuel
to conserve floorspace. Liquid-cooled data centres could also cells at the rack level, very close to the servers, which limits
make use of waste heat. Maintaining a grid connection would the failure domain to a few dozen servers. Other advantages
require thorough consideration to understand the benefits of placing the fuel cells at the rack level included lower-voltage
versus the cost. DC connections and the elimination of expensive data centre
A second benefit is that gas distribution within a data centre equipment, such as power distribution units, high-voltage
is much cheaper than high voltage switchgear, transformers and transformers, expensive switchgear, AC/DC power supplies and
copper cables. If the FCs are placed close to power consumption backup generators.
units, at the servers or racks, one could completely eliminate The research showed that both proton exchange membrane
the power distribution system in the data centre, including the fuel cell and solid oxide fuel cell systems could follow the dynamic
power backup generation system, meaning that no data centre- power demands of servers while operating. However, the fuel
wide electrical infrastructure is required. This is over 25% of the cell systems could need some support from battery energy
storage systems for the extreme transients experienced during
a cold startup. The overall efficiency of delivering power to the
servers starting from natural gas was shown to be 29,5%. This
is compared to the utility grid network provision of power also
starting from natural gas at 17,5% efficiency. 7

References
1. G Saur, et al: “Hydrogen and Fuel Cells for Data Centre
Applications Project Meeting: Workshop Report”, Technical
Report NREL/TP-5400-75355, December 2019.
2. A Riekstin, et al: “No more electrical infrastructure: towards
fuel cell powered data centres”, HotPower ’13, November
2013.
3. R Miller: “eBay Goes Live With its Bloom-Powered
Data Centre” http://www.datacentreknowledge.com/
archives/2013/09/26/ebay-goes-live-with-its-bloom-powered-
Figure 3: Gain in efficiency using distributed FC power (Microsoft) data-centre/
4. AKCP: “Fuel cell powered data centres”, https://www.akcp.
com/blog/data-centre-fuel-cells/
5. G Saur: “Hydrogen and fuel Cells for Data Centre Applications
Project Meeting: Workshop Report”, NREL/TP-5400-75355 :
2019
6. J Brouer: “In-Rack Direct DC Powering of Servers with Solid
Oxide and Proton Exchange Membrane Fuel Cells”, https://
www.energy.gov/sites/prod/files/2019/04/f62/fcto-data-
center-workshop-2019-brouwer.pdf
7. L Zhao: “Fuel Cells for Data Centres: Power generation inches
from the Server”, Microsoft Research Technical Report MSR-
TR-2014-37.

Figure 4: Microsoft data centre with fuel cells for each rack (Microsoft) Send your comments to rogerl@nowmedia.co.za

energize | December 2022 | 39