another concept i've been thinking of is doing more with power. i think some elements should require power to function, which would be deducted from the total that you can bank/sell. also, it seems that excess power that you generate but can't store or get rid of should be returned to the reactor as additional heat.
would be fun if fuel cells distribute heat differently. instead of heat going only to reactor or occupied sides, set them to radiate a percent to each side; for any unoccupied side, that portion of heat goes to the reactor. would give more flexibility to combine direct/indirect cooling. VARIANTS: 1) occupied sides get 25%, reactor gets what's left. 2) occupied sides get 20%, reactor gets 20% + what's left (reactor always gets some heat, requires some indirect cooling in all builds). 3) occupied sides get 20%, reactor gets 20% + what's left; reactor never gets more than 80%. if all sides unoccupied, fuel cell stores the remaining 20% (have to add heat storage to fuel cells). 4) add an exception for heat exchangers/inlets allowing them to override percentages and move as much heat from fuel cells as the exchangers/inlets would otherwise be capable of (so, high-powered exchanger next to a fuel cell could actively take 100% of the cell's heat, rather than passively accepting 20 or 25%).
 "Reactor Incremental"){kind=icon}