\cite{Runvik_2015} The economic optimization of af DH system with multiple production units and consumers is a Mixed Integer Non-Linear Problem (MINLP). This is very hard to solve. The authors circumvent this by splitting up the problem in a unit commitment problem (MILP) and an economic dispatch problem (NLP). They solve a fairly short horizon and have very basic modeling of the consumption pattern. Interesting conclusion: They find an economic value in decreasing production peaks. (last line of their conclusion)