Its possible to buy explosives to remove the stumps. Here you must obtain a
license from the county before you can purchase explosives. Its not cheaper
then grinding. When you are done removing them with explosives you have a
large hole in the ground that will need to be filled and a large stump that
will need to be disposed of in some manner ( you said no fire). Grinding
makes a lot of sense. A lot of stumps can be done in a day. I like to burn
my stumps. I simply build a small fire on top of the stump and add some
more fire wood every few hours. Usually takes about a week.