The phrase "to grow the biomass" means to increase the amount of living matter (such as plants or bacteria) that can be used for various purposes, like producing fuel, food, or materials. Full definition
At a slightly higher price farmers would start specifically growing biomass for sequestration purposes. (johnquiggin.com)
For example, growing biomass takes CO2 out of the atmosphere, while burning it releases the gas again. (bbc.com)
You are also competing with the food chain because land that could have been used to grow food to eat is instead used to grow biomass for a power plant. (cleanbreak.ca)