Startup cost calculation
In the start-up phase Backbone generates for free except for the constant costs due to 'StartCost' and 'StartFuelCons'. If these costs are smaller than the value of fuel that would be needed to generate the start-up phase electricity, then it's cheaper to produce electricity in start-up than in normal operation. The longer the start-up takes, the more electricity the unit generates. In principle correct values for 'StartCost' and 'StartFuelCons' would make this go away, but it's easy to make a mistake. Also if the unit starts right away, then there is no 'free' electricity generation (now we assume start-up takes one time step, even when it takes only 1/10th of the time step).