Yeah. Keep it in big bins and pour old urine over it. Let it work, and stir it every so often. When it's well fermenting, let it dry and then wash it. Carefully pour off the wash water, discarding the sludge. Evaporate and save the white crystals -- that's potassium nitrate and is used in making your own gunpowder! Yes! You can make your own fireworks!

All you have to do is put up with all those complaints from the neighbors and your spouse and the Health Department and the EPA and all those sorts of nay-sayers and partypoopers. Of course, there is also a teeny-weeny bit more to it than I just described. I do suggest that you keep your house UPWIND from the tanks, though. (You can also toss in night soil, the stuff from old barns and corrals and cattle yards, just all kinds of shit!)