Vital to survival. Everything runs on batteries these days.
It is possible that the batteries have a much longer life and/or are more powerful then modern batteries. There are at least two plausible theories to how they became the main energy source for the area immediately controlled by Better Living Industries. Since they are never seen to be recharged and are simply dispensed from vending machines such as the one shown, it is safe to assume that such commodities are disposable.
It is possible that the batteries are of the dry cell variety and rely on an extremely concentrated galvanic reaction. This would allow for a much smaller galvanic cell, allowing more to be stacked together and ultimately, increasing both voltage and current. These could easily be created by the vending machines on site with only simple chemicals that are replenished by employees. The ultra-concentrated solution would be extremely dangerous if disposed of incorrectly and thus, would force BL/ind to recycle the spent casing and simply top it off with fresh chemicals.
Another possible explanation is a replacement of chemicals with super-capacitator plates made of carbon nano-tubes. As carbon-nano tubes can currently be grown with only some degree of dificulty, it would only be too easy for a quasi-government corporation to be able to farm these with relative ease, especially in the future. Drastic improvements would allow the super-capacitator plates to be grown cheaply and also allow for massive charges of voltage and current to be stored. These would be manufactured at a BL/ind facility and then shipped off to be used and disposed of with little relative impact on an ecosystem.