What should PJM do with non-firm transactions not willing to pay congestion?

Re-dispatching generation is the appropriate response when dealing with non-firm transactions that are unwilling to pay congestion charges. This process involves adjusting the output levels of power plants to alleviate congestion on the transmission system. When non-firm transactions are involved, it indicates that these transactions do not have a guaranteed right to transmission service, and thus, when congestion occurs, the transmission system must react to ensure reliability and stability.

Re-dispatching works by either increasing the generation at some power plants while reducing it at others, effectively managing the flow of electricity through the congested areas. This not only helps in maintaining system reliability but also facilitates the continued operation of the grid in an efficient manner. It is essential to have a responsive and flexible system, especially when non-firm transactions are present, as they can impact the overall operation and reliability of the grid if congestion issues arise.

Other options such as loosely managing, monitoring, or suspending do not provide the proactive and concrete steps needed to address the immediacy of congestion. These strategies lack the necessary intervention required in the context of managing non-firm transactions effectively.