Past exam of the MPhil in micro- and nanotechnology enterprise course of the University of Cambridge / 2020 / Paper 1 / Section A(iii) / 6 / ii / Solution

The stored energy is $0.75(7)=5.25\mathrm{Wh}$, and the load draws $P=IV=(20\times 10^{-6})(2.5)=50\mu \mathrm{W}$. HenceThis is an ideal energy-budget estimate using 365.25 days per year. It assumes the stated energy is usable at this load, constant current and voltage, and negligible self-discharge, ageing and reserve capacity. No biological operating model is required.