Nowadays, power plants need to operate flexibly. Whereas a constant electrical output was the norm in the past, production at today's conventional plants needs to fluctuate because of the increasing use of energy from renewable sources. Erich Schmid had developed a whole range of operating processes that quickly increase electricity production in combined cycle power plants and maintain this higher production level for a specific period of time. The resulting rapid increase in electricity production is especially important in what is known as the frequency stability mode. Here, sudden differences between the required and the actual amount of electricity generated are balanced. Such differences can lead to changes in the line frequency. In the worst case, the discrepancies can cause the grid to break down completely. For this reason, network operators purchase reserve output from electricity producers. Any power plant that is required to provide reserve output must be able to deliver the contractually agreed-on output within just a few minutes — and sometimes even within seconds. Erich Schmid works in the Energy sector in Erlangen, Germany.