How do open journals keep the lights on?
Scholarly societies may publish open access journals. In this case, the costs of maintaining the journal are covered by membership fees.
This model is commonly associated with open publishing in general. In fact, the majority of open access journals do not charge author processing fees, but many journals do use this strategy. This money may come from the grant under which the research was done, so if you are working in a subject area in which this is common practice, you should consider writing these fees into your grant. Alternatively, authors' institutions sometimes pay the fees.
Books and journals published by university presses may be subsidized by their host institutions.
There are a variety of models here, but they involve support from a group of institutions.
Journals are still experimenting, so there are many other models available. Please read more about them below.