Strategies for the use of biochar for climate change mitigation

1. Strategies for the use of biochar for climate change mitigation Kevin Steinberger Internship with Princeton Environmental Institute – Working with Dr. Eric Larson and the Energy Group

2. What is Biochar? • Biochar (or agri-char) def: “Stable, carbon-rich charcoal that results from pyrolysis of biomass”1 • Slow pyrolysis: thermal decompositionthat is performed at a low heating rate, and with a low final temperature • Recent interest in biochar was inspired by study of Terra Preta soils in the tropics2 • Recent studies have focused on the application of biochar to soil: • Soil improvement, carbon sequestration, and energy by-products Image taken from McGill University: http://www.mcgill.ca/macdonald/alumni/newsletter/ebulletin/2009-12/research

3. Internship Goals and Progress • A group of researchers (Roberts et al) have performed a life cycle analysis of the energy, Greenhouse Gas (GHG) emissions, and economics of biochar production1 • “Life Cycle Assessment of Biochar Systems: Estimating the Energetic, Economic, and Climate Change Potential” (2010) • First goal: create Excel model to examine these findings, and to be able to study the sensitivity of their results to certain variables and assumptions • Thorough literature review was performed to determine the range of cost estimates for various aspects of the entire biochar production process • Using Excel model, completed a separate analysis of the economics of biochar production using data found in the literature • Determined the impact of conflicting assumptions on the economic viability of a project

4. Internship Goals and Progress (cont’d) • Second goal: write a scientific report to analyze the impact of producing biochar at a slow pyrolysis facility and then applying the biochar to agricultural soils • “Review and Assessment of Biochar Strategies for Climate Change Mitigation” (still in progress) • Summarizes the current literature on biochar and identifies needs for future research • Report focuses on understanding the conditions under which favorable economic and environmental results can be achieved, by discussing all of the economic factors involved and examining the assumptions behind these factors

5. Economic Analysis: Outline • Capital – Pretreatment and Pyrolysis Costs • Sensitivity to Capital Recovery Factor (CRF) • Comparison of estimates found in literature • Operations and Maintenance • CO2 Offset: Varying emissions trading prices • Stable C in soil • Reduced N2O and CH4 emissions • Energy Value • Best and worst case estimates • Sensitivity to fuel prices • Fertilizer • Nutrient content of biochar • Increased soil efficiency • Cost of biomass • Land Rent and Field Operations • Agrochemicals and lost nutrients • Total Cost • Future Analysis Figure 1: Biochar production/application process outline

6. Results • Many of the assumptions made by Roberts et al in their analysis conflicted with other estimates found in the literature: • Cost of biomass collection and transportation • Capital costs for pyrolysis plants • Large uncertainties that need more research: • Energy value of by-products of pyrolysis process • Effects of biochar implementation on crop yields, and the monetary value this would have for the farmer • In reality, especially without an emissions trading scheme, the production of biochar is not currently economically favorable

7. Results (cont’d) Table 1: Baseline, best case, and worst case economic scenarios for biochar production/application

8. Conclusion • Under current conditions and assumptions, the production of biochar is not economically viable • However, with more research and improved technology, and an emissions trading scheme, the economics could change dramatically and biochar production may emerge as a profitable strategy for climate change mitigation • Senior thesis: Design a gasification process, using Aspen software, to improve the economics by optimizing energy and char yields • This internship also confirmed my enthusiasm for the field of renewable energy, and I plan on continuing my studies in graduate school next year • Thanks so much to PEI and Dr. Larson for a great summer internship!

9. References 1. Roberts, Kelli G., Gloy, Brent A., Joseph, Stephen, Scott, Norman B., and Johannes Lehmann. “Life Cycle Assessment of Biochar Systems: Estimating the Energetic, Economic, and Climate Change Potential.” Environmental Science and Technology.44.(2010): 827-833. 2. Woolf, D. et al. “Sustainable biochar to mitigate global climate change.” Nat Commun. (2010). 3. "Practitioner's Profile: Using Chicken Litter for Biochar | International Biochar Initiative." International Biochar Initiative | International Biochar Initiative. Web. 14 July 2011. <http://www.biochar-international.org/Frye/Poultry>. 4. Hooper, Troy. "Hope Mine Cleanup Banking on Biochar." Real Aspen 6 Oct. 2010. Web. 5. Pers. Communication