1. Bio-based electricity: How biomass resources can support renewable electricity policies Matt Kocoloski and Paulina Jaramillo Carnegie Mellon University Tepper School of Business RenewElec Workshop Presentation October 22, 2010

2. Overview Biomass may be used to generate low-carbon energy compared to fossil fuels Policies encourage use of biomass for both transportation fuel (RFS, LCFS) and electricity (RPS) Project will examine benefits of using different biomass feedstocks and conversion technologies to meet different types of electricity demands in order to inform renewable electricity policies 2

3. Feedstock Characterization 3 500 Mtons of biomass ~ X million kWh

4. Feedstock Characterization 4 Switchgrass: perennial, low-input grass; potential energy crop Photo courtesy sciencedaily.com

5. Feedstock Characterization 5 Photo from Glassner (1998) Corn Stover: portion of plant remaining once crop has been harvested

6. Feedstock Characterization 6 Forest residues: generated by logging operations, timberland clearing, or thinning measures Photo from nrcs.gov

7. Feedstock Characterization 7 Photo from EIA Primary mill residues and municipal solid waste: wood wastes generated by industrial or urban operations

8. Feedstock Characterization 8 Feedstock Type CostPotential Supply Currently Available Alkali Content Feedstock Impurities SwitchgrassHigh NoHighNo Corn StoverMedium YesHighNo Forest Residues HighMediumYesLowNo Urban/Mill Residues Low YesLowYes/No

9. Conversion Options Cofiring biomass with coal –Biomass blended at low- levels with coal and used in current boilers –Limited capital costs, but limited potential (5 – 10% in regions with coal-fired capacity) 9 Figure from Morrow (2008)

10. Conversion Options Dedicated biomass combustion –Requires boiler replacement, but may be option for older coal plants to meet emissions regulations 10 Diagram from EERE

11. Conversion Options Biomass gasification –Biomass converted into syngas, which powers a gas turbine –High capital costs, but may be better suited to load- leveling and CCS 11 Diagram from Rhodes (2005)

12. Conversion Options 12 Conversion Technology Capital Cost Generation Potential Regional Limitations Adds Capacity Ramping/Load- Leveling Ability Cofiring with coal Low YesNoLow Dedicated combustion Medium YesNoLow GasificationHigh NoYesHigh

13. Research Questions 1.What types of electricity demand should be met using biomass? Should biomass be used primarily to meet base load demands, peak demands, or coupled with intermittent renewable technologies (such as solar and wind generation) to act as a load-leveler? 13

14. Research Questions 2.What technologies should be used to convert biomass into electricity? Should conversion to electricity be accomplished through cofiring biomass with coal, dedicated biomass gasification or combustion, or in a combined heat and power system? 14

15. Research Questions 3.How does uncertainty in biomass feedstock availability impact electricity generation options? How does regional variability in electricity generation infrastructure impact conversion options? 15

16. Summary Biomass may make a positive contribution to meeting environmental goals for electricity generation Interesting decisions regarding: –Feedstock type –Conversion technology –Electricity demand type Project intends to explore these interconnected decisions with the goal of informing renewable electricity policies 16