Can someone please recommend an ad network that we can use for a green site. We would like to display all green and ethically responsible ads.

There is no such thing like green ads.

I remember that I was in a similar dilemma some time ago when I was working for a beauty product pitch and my team thought going green was one advertising strategy. I found this link back then and it is old but I thought its good insights on the green advertising networks.

Thank you. This is a very helpful link.