Biomass pyrolysis with biochar returned to soil is a promising strategy for climate change mitigation and reducing fossil fuel consumption. Biochar is the stable, carbon-rich charcoal that results from pyrolysis of biomass materials. Used as a soil amendment, biochar improves soil health and fertility, soil structure, nutrient availability, and soil water retention capacity, and is also a mechanism for long-term carbon storage in soils. Slow pyrolysis of biomass in an industrial-scale facility results in four co-products: long-term carbon sequestration in the form of stable carbon in the biochar, renewable energy generation, biochar as a soil amendment, and biomass waste management. Life cycle assessment (LCA) was used to estimate the net energy, climate change impacts, and economics of biochar production. The feedstocks analyzed represent agricultural residues (early and late harvested corn stover), an organic waste source (yard waste), and energy crops (switchgrass cultivated on both marginal and annual croplands). For all feedstock scenarios, the net energy of the system is positive, i.e. more energy is generated than consumed. The excess syngas energy ranges from +2000 to +4000 MJ per tonne of feedstock. The net greenhouse gas (GHG) emissions for both stover and yard waste are negative, indicating that for each tonne of feedstock, more than one-half tonne of CO₂ equivalent reductions are made. Meanwhile, the switchgrass results highlight the critical role that indirect land-use change plays on the life-cycle climate change impact of energy crops. Switchgrass developed on marginal land has the potential to sequester carbon, however, switchgrass produced on land diverted from annual crops results in net GHG emissions. The economic viability of the pyrolysis-biochar system is largely dependent on the costs of feedstock production and pyrolysis, and the value of carbon offsets. Biomass sources that have a need for waste management such as yard waste have the highest potential for economic profitability and environmental sustainability.