Biomass & Biofuels

1. Biomass & Biofuels San Jose State University FX Rongère March 2009

2. Biomass 2nd Renewable in California • California Gross System Power for 2006 (GWh) Source: CEC http://www.energy.ca.gov/electricity/gross_system_power.html

3. Bio-fuels: Clean and Renewable Energy? • Biomass stores energy and carbon Source: Boyle, Renewable Energy, 2nd edition, 2004

4. Conversion rate • Typical solar energy in the Central Valley : 6 kWh/m2/day Biomass conversion and storage rate: 0.5%

5. Effective radiation on photosynthesis Solar Spectral Irradiance (103 W.m-2.μm) λ (m) Conversion No conversion

6. Carbon Balance • Theoretically: • Biomass is carbon neutral • Actually: • Additional CO2 emissions for: • Planting, Maintaining and Harvesting • Water management • Fertilizer • Biofuel manufacturing • Avoided decomposition GHG emissions for residues • Life cycle analysis depending on the bio-fuel and technologies

7. Global Warming Potential • GWP: Normalized index provided by the Intergovernmental Panel on Climate Change (IPCC) • IPCC was established in 1988 by two United Nations organizations: • the World Meteorological Organization (WMO), • the United Nations Environment Program (UNEP), to evaluate the risk of climate change caused by human activity. • IPCC shared the 2007 Nobel Peace Prize with former Vice President Al Gore.

8. GWP • By definition: • Time Horizon is very important because of the complex decay of the chemical components in the atmosphere

9. GWP • Values provided by IPCC in 2001 Source: IPCC Climate Change 2001 The Scientific Basis http://www.grida.no/climate/ipcc_tar/wg1/index.htm

10. Net life cycle emissions from Electricity Generation Source: Boyle, Renewable Energy, 2nd edition, 2004

11. Net Life Cycle Greenhouse Gas Emissions • Taking the avoided decomposition methane emission into account forest residue direct combustion may have a negative GWP Source: Margaret K. Mann and Pamela L. Spath LIFE CYCLE ASSESSMENT COMPARISONS OF ELECTRICITY FROM BIOMASS, COAL, AND NATURAL GAS, 2002 Annual Meeting of the American Institute of Chemical Engineers November 2002

12. Resource in the USA

13. Biochemical Conversion Thermochemical Conversion Extraction Anaerobic Digestion Fermentation Direct Combustion Gasification Pyrolysis Liquefaction Steam Gas Oil Charcoal Biogas Ethanol Bio-diesel Heat Electricity Transportation Biofuels • Biofuels cover a broad range of technologies and applications: Source: From Boyle, Renewable Energy, 2nd edition, 2004

14. Direct Combustion • Wood and straw residues are dominant • About 600 MWe in California Location of wood power plants in California

15. Wood combustion • Wood has an energy content of 6 to 18 MJ/kg depending on its moisture • Wood macro-molecules (cellulose polymers) break-down starts at about 300oC (575oF) • It generates inflammable gas (CnHm) which burn with the air oxygen (Gaseous combustion releases about 85% of the energy content of dry wood) • The combustion requires about 5.5 kg of air per kg of dry wood • Remaining charcoal is directly oxidized at high temperature (600oC)

16. Straw-fired power plant Source: Boyle, Renewable Energy, 2nd edition, 2004

17. Typical Wood Power Plant • Example of a 10 MWe industrial power plant in Denmark

18. Steam Cycle    

19. Steam Cycle     Cycle conversion rate: η=35%

20. Humboldt Blue Lake Plant • Restarted in November 2008: 11MWe • Wood consumption: 95,000 BDT of wood (BDT = Bone Dry Ton) • PPA with SDGE

21. Tracy Power Plant • Wood Power Plant in Tracy: 23 MWe • 1,000 ton per day of wood • Built in 1990 • PPA with PG&E

22. Honey Lake Power Plant • Wood Honey Lake Power Plant: 36MW • Wood processing: 1,300 tpd • Built in 1989 • Condensate water pre-heating with geothermal source

23. Gasification • To obtain a better efficiency and a better control of the combustion and pollution, pyrolysis, charcoal gasification and combustion are controlled separately.

24. Gasifier Types

25. Examples of technologies Fluid bed Gasifier (JFE) Counter current Gasifier (Babcock&Wilcox)

27. Integrated Gas Combined Cycle • IGCC is the association of a gasifier, a gas turbine and a steam cycle Biomass Gas turbine generates electricity by direct combustion of syngas Heat of the exhaust gas is recovered to run a steam cycle

28.   Combustion Compressor Turbine   Gas Turbine     Conversion rate: 36% Brayton Cycle

29. IGCC • Steam Cycle Conversion rate: 29%

30. IGCC • Conversion rate • Example: ηIGCC= 55% Fluidized Bed Gasifier in Gussing Burgenland Austria operated on wood chips

31. Wood bio-mass potential in California • Forest biomass represents about 50% of the wood residue resource • The potential for the forestry residue is 27 MM BDT/year (BDT = Bone Dry Ton) Source: CEC An Assessment of Biomass Resources in California, 2006

32. Calculation of the Electricity Generation potential • Energy content: Ec=18 MJ/kg • Conversion rate: η=25% • Capacity factor: CF=85% This potential represents about 10% of the electricity consumption in California and about 15 times what is currently in operation

33. Municipal Solid Waste Source: Boyle, Renewable Energy, 2nd edition, 2004