When we say "humane" we really should mean "humane" to the team that has to do the work.  We need to be focused on their humanity, serenity.  

I am against the death penalty in the US under all circumstances, but if we have it, we have to be concerned with the souls of the people tasked with executing our government's decisions. 

It should be "rare, painless, and safe" (to leverage some nice words from the abortion sub-class).  Affordable too. 

The person being executed has made themselves low priority in the bigger scheme of things.   Their remaining job is a great and full confession to their Father God.  

Most of our role is to pray earnestly for them...maybe fast for them...that they face their God in their hearts and fully reconcile with Him.