Battery acid is not green. However its always a good idea and make sure a wet battery is naturalized with battery acid so you don't get corrosion. If it "fizzes" a lot, than if probably is battery acid, possibly from overcharging (often because the terminals need cleaning).
It's hard to smell small quantities off coolant, but I'd be suspect of it. That location indicates a probable failing heater hose. It usually fails right where it comes out of the manifold. When the leak first starts, its just a pinhole leak so it can spray away from the source, but not be enough to see it leaking while your looking. Eventually (sooner rather than later probably) the heater hose will rupture.
I went through this exercise with my van last spring. Since your van is one year newer.... sound like you're due
If you have rear factory HVAC, the dealer and the parts stores will want well north of $100 for the hose assembly. I got it from Rock Auto for $22. When you do the repair, use the factory style hose assembly and use the factory spring clamp. I tried using hose clamps the first time I fixed it, and that caused the plies of the hose to separate. So I actually did the repair 3 times. Twice with universal hose and hose clamps before spending springing for the OEM style assembly.