The second article, “Fracking, Renewables, and Mean Field Games,” by Patrick Chan and Ronnie Sircar, uses mean field game models to study the competition between traditional oil producers and producers of renewable energy. It gives an overview introduction to the application, from the OPEC price setting and view of fracking to the viewpoint of competitive oligopolies. Mean field games were first introduced in the early 2000s. The idea is that by a systematic application of a continuum approximation, it is possible to get analytical solutions and straightforward computational answers that would be much more difficult in the study of the $$N$$-player system. The paper includes the details of setting the energy market competition problem in this framework and illustrates how to use this method in a concrete numerical example. For those who study systems with large numbers of players or agents, this paper is a nice walk-through of the relatively new analytical technique of mean field games.