(66d) Techno-Economic (TEA) and Life Cycle Analysis (LCA) of the Pyrolysis-Bioenergy-Biochar Pathway for Carbon-Negative Energy

Wenqin Li.^b, Qi Dang ^ab, Wright M. M.^ab, Brown, R. C.^ab, Laird, D.

^aBioeconomy Institute

^bDepartment of Mechanical Engineering

^cDepartment of Agronomy

Iowa State University

The objective of this project is to evaluate the economic and environment impacts of the Pyrolysis-Bioenergy-Biochar Pathway for carbon-negative energy. Biochar, a carbon rich coproduct of pyrolysis, has the potential to improve soil quality by sequestering carbon thus helping to achieve a carbon negative energy goal. In addition to biochar, fast pyrolysis of biomass can also produce biofuels, bio-power and chemicals. Techno-economic Analysis (TEA) and Life Cycle Analysis (LCA) results will vary with the selection of pyrolysis products, feedstock materials, and facility locations.

Economic analysis was conducted on two pyrolysis product utilization scenarios: biochar & biofuel and biochar & bio-power. In the biochar & biofuel scenario, we estimate that the minimum fuel-selling price (MFSP) varies between $2.91 and $3.03 per gallon if biochar can be sold for $60 to $20 per tonne. On the other hand, if the biofuel can be sold at market prices of $2.00 to $5.00 per gallon, the biochar can be sold for $364 to -$637 per metric tonne. The biochar & bio-power scenario yields minimum electricity-selling prices of 9.85 to 10.07 ¢/kWh for biochar prices of $60 to $20 per tonne. Biochar can be sold for -$336 to $400 per tonne at electricity prices of 12 to 8 ¢/kWh. These prices do not include environmental credits or incentives. More pyrolysis product combinations scenarios will be assessed and compared.

Biochar properties and yields vary from different types of biomass. Regression models of relationship between biochar & biofuel yield and biomass carbon, ash & oxygen contents have been built based on series of fast pyrolysis experimental yields data. The regression model was validated for different types of feedstock and used to predict the yield for various feedstocks. Process models for fast pyrolysis of various feedstocks will be built in Aspen Plus^TM, with the products prediction data. Mass and energy balance and subsequent techno-economics analysis will be assessed and compared to elect the best economic performance feedstock.

The pyrolysis facility locations might affect various factors, such as feedstock cost, feedstock type, capital cost, and operating cost. Biochar type and the demand for biochar will also vary with the plant locations. Three specific land areas of US are investigated depending on the selection of pyrolysis facility locations: Upper Mississippi River Basin (UMRB), California, and U.S. Southeast. The capital cost, operating cost and minimum fuel selling price was estimated to indicate the economic benefits of employing integrated Pyrolysis-Bioenergy-Biochar pathway in various regions. Life cycle analysis will also be conducted using GREET to evaluate the GHG emissions of the integrated Pyrolysis-Bioenergy-Biochar production facility in different regions.