how to stop 2050 emissions go negative

[UKTM User]

> what's the main differences between this version and v4.5.6?

I attach a summary of the changes, so you can see what you will be missing.
Among the improvements, the most important new feature is probably the extension for Ancillary Balancing Services (ABS): 
See the ABS Documentation

I have myself been mostly using   barcrossalg 0
I know that some users want to save solution time and therefore disable crossover. While that may work reasonably well if the model is numerically stable, it usually produces solutions that are somewhat non-optimal, and the deviation from the true optimality tends to get bigger when there is some numerical instability. And, as shown by your scenario, at worst it may even produce an infeasible solution even though falsely reported feasible.

Thank you very much for the ABS document, it's very useful for us to decide whether to update to v4.5.6 before migrating to VEDA 2.0. 

I see what you mean for the barcrossalg options, it makes sense and I've changed mine to 0.

Thank you for all your help on this!