On average, a hamster achieves 40 to 60 revolutions per minute when running in its wheel. If the wheel were connected to a generator, this kinetic energy could produce up to 0.5 watts of electricity – enough to light an LED lamp. However, these 0.5 watts is the absolute maximum a hamster could produce. Given that the average hamster only spends around five percent of its life in the wheel, it would really only generate some 0.15 watts. According to a survey conducted by the Energy Agency in North Rhine-Westphalia, a four-person household consumes 5,009 kilowatt-hours of electricity per year. Theoretically, therefore, 3,812 hamsters would need to run all year round in order to power a household. This would require quite a large basement and a fair few hamster cages.
Saskia Blank of the Ideas 2020 team answered this question, with the help of an article from P.M. magazine (in German).