Agenda 1.Quiz on Chapter 4 (5% added to Test 1) 2.Discuss anaerobic digestion and gasification 3.Watch video(s) on “Future of Bioenergy” 4.Example on gaseous biofuel calcs Announcement: No Class on Wed., Sept. 22

Question 1 List the two categories of bioenergy sources, as described by the author. Question 2 According to the Author, “producer gas” from thermochemical gasification results primarily in _________ and ________ with smaller amounts of __________, _________ and _________.

Question 3 List the four ways that liquid fuels can be produced from biomass, as described by the author. Question 4 The most commonly used process to transform syngas into liquid fuels using catalysts is called. __________-_________

Question 5 Plot the concentration of the following gases coming from a landfill vs. time. Use these symbols: O2 = Solid Line N2 = Dotted line H2 = Dashed Line CO2 = X’s CH4 = O’s

✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔✔

Gaseous Fuels Gasification of Biomass/Waste (Thermophysical) Fixed Bed Fluidized Bed Entrained Flow Plasma Arc Anaerobic Digestion (Biochemical) Landfill Gas Manure Digesters Accelerated Digestion of other Wastes

Anaerobic Digestion Microorganisms break down organic matter in absence of oxygen - Breaks carbohydrates into sugars - Then sugars into CO 2, ammonia, hydrogen, and eventually methane Figure courtesy of Alex Marshall, Clarke Energy.

Anaerobic Digestion Overall Reaction Something Like… C 6 H 12 O 6  3 CO CH 4 Wide range of input feedstocks (manure, MSW, etc) Batch or continuous process Single or multi-stage Residence times 2-6 weeks Product gas composition varies drastically CH 4, CO 2, N 2, H 2, etc.

A Dairy Digester

Landfill Gas (Yolo County)

Gasification Typically a partial oxidation process (ϕ>3, 1000 K) - Heat from reaction breaks molecular bonds - Insufficient oxygen to complete reaction - Often, steam is used as well - Major products = CO, H 2, solid residue Gas mixture produced is called “syngas” Syngas can be burned for heat, power an engine Higher temperatures and cleaner burning solid fuel

Zones of a Gasifier Drying – Biomass is dryed Pyrolysis or Distillation Biomass heated by gases and radiation Chemical reactions due to temp, no oxygen Biomass turns to gas, char Reduction – Reactions (CO2, H2O, H2, CO) Hearth (Combustion) – Char burned to produce heat, CO2 and H20 for reduction zone

Counter Current (Up-Draft) Gasifier

Co-Current (Down-Draft) Gasifier

Fluidized Bed Gasifier

Other Processes Carbonization – Like pyrolysis (no oxygen), creates carbon residue from biomass, gas given off Aerobic Decomposition – Composting. Could be used for heat, low temperatures Solid Biomass Combustion – Not hard, not clean

✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔✔ ✔✔ ✔ ✔ ✔✔ ✔ ✔✔

✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔✔ ✔✔ ✔ ✔ ✔✔ ✔ ✔✔ ✔

The Future of Biofuels Potentially new pathways… Any source  Gasification  Reforming  Fuels

The Future of Biofuels