I'm responsible for being sure four 2000 kW Cat gensets will start and run at any time. One of the bosses decided we should have air starters to back up the TWO per engine 50MT starters. I made up a list of pros and cons. Basically, I told them the same thing. Without air and in a blackout, where would I get compressed air from?? With my current arrangement, I have two pairs of 1300 amp 8D batteries in parallel per engine. I have a cart with two 8D's, a charger and cables. Then I keep two starters and a battery charger in stock. PLUS my best friend owns a battery store. I have 24 hour access to batteries. That was the end of the air starter discussion.