At how many watts, though. Chemical galvanic cells can endure for many decades if they are only called upon to furnish a maintenance charge. I remember a Leclanche standard cell owned by a university electrical engineering department that was still putting out full voltage after 79 years.
The battery uses a process called betavoltaics, which is a non-thermal converter.The device gathers energy from the beta-particles that pass through a silicon diode, in a manner analogous to photovoltaic cells.The author wrote a another piece which I will include. It does not mention it the watt power outage