We are wanting to use the Alder for firewood and wondered if it was a hardwood or not.
It is a hardwood; you can make furniture out of it besides firewood.
https://www.gardeningknowhow.com/ornamental/trees/alder/alder-tree-information.htm
https://owic.oregonstate.edu/red-alder-alnus-rubra
https://forestry.usu.edu/forest-products/wood-heating