Natural Laundry Detergent or Additive to cut grease?

We have been slowing moving over to more all -natural things at the house, including cleaning supplies.  However, I am having a problem finding something that really works well on my husband's laundry.  He does HVAC so he tends to have a lot of dirt, grime and grease on his clothing and I just can't find anything that gets rid of both the stains and the smell.  Does anyone have any experience or suggestions?

Thanks!