Power plants for district heat should really be must-run plants in winter and participate in merit order in summer

[AlexanderWirtz]

Currently, power plants for district heat are dispatchable in the merit order calculation. They are also penalized for their loss of electrical efficiency. Instead, they should probably be normal power plants in summer and must-run CHPs in winter. As such their output powers would be described by a step function, depending on whether hour X occurs in winter or in summer. The same is true for electric / heat efficiencies. Input power is constant, of course

• The exact months for delivering heat to the heating grid need to be researched, as should the profile
• The efficiencies under both circumstances need to be researched and validated
• Impact on the merit calculation of such an approach needs to be assessed

@ChaelKruip and @dennisschoenmakers do you think this is feasible?

[ChaelKruip]

Closing this because https://github.com/quintel/etengine/issues/706 will take care of this (although slightly simplified).