APC 400kW1MW User Manual download pdf (Page 28)

3.3.2 Fuel Cells as Secondary Power

Because of the disadvantages associated with diesel generators, some data center

owners are considering fuel cells for emergency power. The disadvantages associated with

diesel generators include reduced system reliability from engines failing to start due to a lack of

maintenance or testing, high amounts of emissions, and local complaints caused from visible

smoke, noise, and odors [1, p. 80].

Fuel cells have a promising application of providing reliable backup power because

users in the telecommunications industry may be willing to pay a premium for it. Although fuel

cells may be costly compared to other back up power alternatives, the high reliability and ease

of siting due to the low emissions of fuel cell systems could make them more attractive than

conventional backup power systems [11, p. 48].

With a utility connection as the primary power source and fuel cells providing secondary

power, the DOE has concluded that providing hydrogen tanks for the fuel cell’s fuel supply is

preferable over fuel reforming. Their reasoning is that starting a fuel reformer for backup power

for every utility outage would be expensive and energy inefficient. Also, the start up times for all

components would be extensive from having to reach operating temperatures. Additional

battery storage would be necessary in order to provide power during this long start up time,

which would increase capital costs, as well [35, p. 1]. Figure 3-4 shows four hydrogen storage

tanks located outdoors. From the storage tanks, the hydrogen is routed in stainless steel tubing

to fuel cells providing secondary power [36, p. 1].

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APC 400kW1MW User Manual Page 28