The Greening of Xohm

Sprint's new Xohm network won't just be the fastest network it has ever built. Sprint intends for it to be the greenest network it has ever built. It won't be solar- or wind-powered. The base stations may not be biodegradable. But in a power industry, where baby steps are considered giant strides, Sprint has decided to rely on fuel cells as the primary backup power source for its WiMAX network.

In its request for proposal (RFP) for WiMAX site design, Sprint has specifically included provisions for fuel cell alternatives as the backup power source, making this the first time it has begun a network buildout with fuel cells written into its plans. With a greenfield opportunity for deployment, Sprint can take steps to create a greener network less reliant on diesel fuel and lead-based batteries — an opportunity it simply didn't have when it deployed its CDMA networks, said Doug Smith, chief technology operations officer for WiMAX for Sprint.

“We certainly see this as an opportunity to make WiMAX as green a technology as possible,” Smith said. “Given that we're building a brand new network, if we can start with fuel cells, we can really move the needle on the technology.”

Because WiMAX by nature is a low-power technology, it is an ideal guinea pig for a fuel cell deployment, Smith said. WiMAX base stations consume less electricity than their cellular counterparts, and because many of the macrocells are hardened to require no external cooling elements, the drain of air conditioning units is often not a factor.

But just as the scenario and the technology themselves offer advantages, the relative infancy of fuel cell technology presents logistical problems. Smith said moving to fuel cells isn't just a simple matter of buying up equipment and deploying it in the network — the support infrastructure isn't completely in place. Fuel cells use a chemical process that converts hydrogen and oxygen in the air to water, the byproduct of which is an electrical current. Those cells need a constant supply of hydrogen to operate. Ideally, the same technicians that refill Sprint's current stock of backup diesel generators and replace drained batteries could be used to replenish hydrogen stores at sites, but many of those contractors aren't yet equipped to deal in hydrogen.