Power grids are the biggest machines on Earth. They are also the most complex ones, as they involve human beings and their complex correlated electricity consumption patterns. In this talk I will give some short overview on data-driven research dealing with frequency fluctuations in power grids. Whereas variations in the dynamics of renewable energy generation are reasonably well studied, a deeper understanding of the variations in
consumer consumption dynamics is still missing. I will talk about highly resolved residential electricity consumption data of Austrian, German and UK households and introduce a stochastic model to quantitatively capture the highly intermittent demand fluctuations.