The companies will form a joint business as early as spring, combining their expertise in power supply control and information technology to offer the service for building reconstruction or redevelopment projects.
The service will tap storage batteries that NTT uses to maintain its communications network hardware when the power supply is cut off. The telecom company operates network hardware at roughly 1,200 sites within Tepco's service area in greater Tokyo.
These lead-acid batteries will be updated to lithium-ion versions over the next decade. The more compact batteries will come with about triple the capacity of lead-acid counterparts in similar sizes. NTT's aggregate capacity would rise to an equivalent of eight fossil-fuel power plants -- enough to supply 100 buildings of 20 stories each for a day.
Large buildings and commercial facilities in Japan often have an emergency power source. NTT and Tepco say their service would eliminate the need for these emergency sources and cut costs by about 20%.
The service also could support power generation derived from renewable energy, which fluctuates based on the weather. Surplus power from solar, wind and other natural sources could be stored for use when the power generation is insufficient.
Tepco urgently needs to cultivate new earnings sources, with the company hampered by cleanup costs tied to the Fukushima Daiichi nuclear power plant meltdowns in March 2011. The joint business lets Tepco share the investment burden.