Yet another one of my bathroom-induced ideas.
Yellow alert would be similar to e-burn in that it's an active, time-limited ability.
I'm not going to be too specific with numbers, but the idea is you'd activate it and it would inflate your fleet's combat readiness and add 10-20% burn speed. This would come at the cost of increased supply consumption and (doubled?) recovery costs, and multiplied repair/recovery time (scaling back to original CR) after a battle is fought in yellow alert. This would allow you to invest more in an individual battle, and allow you to catch up to a fleeing fleet outside of E-burn, but make you much more vulnerable than you otherwise would be once the battle is over.