Okay, so if you really wanna be green, I guess you wouldn't have a microwave. But, I do. It's very rare (I've only known one couple - ever!) to not own a microwave and more than that, rely pretty heavily upon it.
So, since you use it so often, it gets dirty. And, dear hubby and kiddos do not make it any easier with their lack of covering messy dishes, etc.
I have found the best FREE (well relatively depending on what you pay for water!) and GREEN way to clean it!
Simply fill a bowl with water and heat in your microwave for 4 minutes. Let stand inside ONE minute, and voila! Wipe away the yuckies.
It's the simple magic of CONDENSATION! And, it works better than powerful chemical cleaners AND elbow grease put together!!!
I just did this. I wish I had taken before and afters, because it is amazing. And simple. If it doesn't come completely clean the first time, try again, the whole concept of what is behind the cleaning power is a lot like a sauna. Get it nice & steamy in there & then wipe clean! ENJOY!