A distributed network would require gas lines or tanks, or perhaps has many as 20 batteries, at each enclosure. The drawback to centralised, of course, is that it calls for much larger facilities that require a certain amount of real estate and a battery of local zoning and environmental approvals. Still, many operators are finding out that most local zoning boards are more amenable to one large power station rather than a multitude of smaller ones. Once the basic power architecture has been determined, the next question is what kind of power to use. Most experts agree that batteries will continue to be the industry mainstay for the next few years.
Batteries are cheap, reliable and relatively easy to maintain.
The dilemma, or course, is how much battery back-up to provide. Ensuring enough emergency power exists to see the network through a region-wide power outage or to get a technician out to fix a network problem means a minimum of eight hours for most systems. However, some operators are offering as much as 24 hours. But again, areas with less reliable power grids are going to find batteries difficult to use. If you are recharging off a grid that is only up for eight hours per day, the batteries won't fully recharge and your back-up over the course of a week will drop.