Abstract: A method for use of biomass waste to seal a well, includes the steps of: locating a well to be sealed, the well having a lower plug and casing; providing biomass waste; introducing the biomass waste into the casing of the well to fill the casing with the biomass waste to a level above the lower plug; and setting an upper plug immediately above the level of biomass waste.

Abstract: A method for disposing of biomass waste. The method includes locating an abandoned mine having a first well drilled into or through the abandoned mine. Water is removed from a mine cavity through a second well drilled into or through the abandoned mine. The water from the mine is combined with a biomass waste that is at least 70 wt. % carbon to provide biomass waste entrained in the water. The biomass waste entrained in the water is pumped through the first well into the mine cavity to fill the mine cavity. As the biomass waste settles in the mine cavity, the water used to entrain the biomass waste is recirculated to combine with additional biomass waste.