NSF STC Sustainable Futures Research Overview

							Biomass, Biogas, and Biofuels

             Jerry Schnoor
 Dept of Civil & Environmental Engineering
 Center Global & Regional Environ Research




      Sustainable Systems Class
             April 20, 2009
Image courtesy of NASA/GSFC
              Biomass, Biogas, and Biofuels

•   Biomass can be turned into all
    sorts of products
     – Combustion to form heat
        and power
     – Anaerobic digestion to form
        methane and CO2 (biogas)
     – Fermentation to form
        ethanol and CO2 (biofuels)
     – Thermochemical conversion
        to form mixed alcohols
        (biofuels)
     – Synfuels to form H2 and
        carbon monoxide
        (hydrogen as an energy
        carrier)
Some sources of Biomass
Biomass like corn can be used for food, feed, and
 fuel -- it can make a rich array of products with
                 much value added
•   One bushel of corn equals:
     – 31.5 lbs starch/food
     – Or 33 lbs of sweetener
     – Or 2.8 gallons ethanol
           • + 13.5 lbs gluten feed
           • + 2.6 lbs gluten meal
           • + 1.5 lbs corn oil
           • And 40 permanent jobs
             for a 50 million gal/day
             production facility
•   Fine chemicals, enzymes
•   Calls for end of subsidy
    ($0.51/gal) in U.S.
Renewable Energy from Biomass (burning wood
and bioethanol) is already equal to Hydroelectric
Power among renewables, but it’s only about 4%
    of U.S. total primary energy production
Midwest has good Biomass Energy Potential
Probably the simplest idea is to burn the biomass
   to make power (oat hulls, switchgrass) for
 $4/MMBTU but this may not be the best use of
    the feedstock (e.g., specialty chemicals)

                                       Net zero GHG
                                       emissions
Total Flowchart for Biomass and Processes
     Chemistry of Biomass, Biogas, & Biofuels


• Photosynthesis from the sun to form sugars (biomass) --
  Primary Production is forward rxn and Respiration is back rxn
   – 6 CO2 + 6 H2O = C6H12O6 + 6 O2
• Anaerobic digestion has at least two steps overall
   – C6H12O6  3 CH3COOH
   – 3 CH3COOH  3 CH4 + 3 CO2
• Fermentation to alcohols
   – C6H12O6  2 C2H5OH + 2 CO2
• Hydrogen synfuels
   – C6H12O6  6 CO + 6 H2
• Biochar
   – C6H12O6  6 C + 6 H2O
    Some Heats of Combustion in MJ/kg (106 J/kg)


•    Hydrogen       141.8 MJ/kg   •   GHG emissions per MJ of
•    Methane        55.5              complete combustion in
•    Propane        50.35             (kg CO2/MJ)
•    Gasoline       47.3               – Methane 0.0495
•    Ethanol        29.7               – Ethanol 0.0644
•    Coal anthra.   27.0               – Gasoline 0.0672
•    Ammonia        22.5               – Coal      0.0919
•    Coal lignite   15.0
•    Wood           15.0
An Integrated Biomass Production System
Biogas from cows in India is called Gower Gas
Biogas Anaerobic Digester
An Integrated Biogas System from Horse Stables
HAASE Community Biogas Digesters in Germany
HAASE System of Biogas Digestion for Combined
  Heat and Power in Germany (very efficient)

 Combined heat and power generates
 neighborhood steam and electricity
              BIOFUELS in US -- Ethanol Facilities and Major Aquifers


100 mgy
ethanol
production
requires
irrigation
water
equivalent
for city of
2 million




                                            J. Ward, USGS, written commun.
Lincolnway Energy Plant, 50 mgpy ethanol
  18 million bushels of corn per year
  200 million gallons water per year
  (4 gallons H2O per gallon ethanol)
        Conversion of corn kernels to ethanol


• Starch from the corn is hydrolyzed in the presence of enzymes
  to make sugars

• Sugars are fermented by yeasts and fermentation bacteria
  (enzymes) to make ethanol and CO2

• Ethanol is distilled to get to azeotropic purity (95.5% ethanol)
  and then dried to get to pure (neat) ethanol

• Bottoms product of the fermentation/distillation is used to
  make an important co-product, Dry Distillers’ Grains, which is
  sold as animal feed, especially for ruminant animals. DDG is
  rich in protein and oil content.
                                                VOCs
                                              generated?




                                                       High-BOD wastewater ( 100 g/L COD)


High-quality water to make ethanol results in discharges (Parkin, et al 2007)
  - Reverse Osmosis or Ion Exchange results in TDS permitted discharges
Biodiesel refineries from soy beans result in high organic discharges
          Environmentalist’s Energy Balance
           (Iowa Biofuels Task Force, 2007)

                        Motor Fuel Energy
       Energy Ratio                            Greenhouse Gas Metric
                         Fossil Energy In
                                                                            Motor
                                                                             Fuel
                                          Crop
                                                                            Energy
                                         Energy




Diesel fuel for production    Energy to             Thermal   Electricity
    & transportation         make fertilizer        Energy
 Comparison of Ethanol to Gasoline (Biofuels Task Force, 2007)


Stakeholder                        Energy Ratio                   Grain   Gas-
                                                                  EtOH    oline


Plant Engineer                                                    0.38    0.84
                                Motor Fuel Energy
                        Feedstock Energy  Pr ocess Energy

Environmentalist              Motor Fuel Energy                   1.3*    0.81

                               Fossil Energy In
National                                                           14     0.81
Security Advisor               Motor Fuel Energy
                           Petroleum Derived Fuels In

* Average of 14 different study groups. Range is 0.44 to 2.1. This energy ratio
  becomes very large (>10) as we replace fossil energy with renewable energy in
  the production of ethanol (or other renewable motor fuels).
 GHG emissions from nitrogen fertilizers on corn
  and from clearing land can cause the LCA for
  GHG of corn ethanol to become unfavorable

• Recent Research Results
  on GHG life cycle
  assessments:
- Schultz & Isenhart, Iowa
  State University
- Searchinger et al., Science
  319, 2008.
- Fargione et al., Science
  319, 2008.
- Crutzen et al., Atmos.
  Chem. Phys, 8, 2008.
Greenhouse Gases Reduced by Carbon Storage in Agricultural Soils
– Cellulosic ethanol from switchgrass is considered more
sustainable than producing ethanol from corn
   (pounds/acre/year)
                1400


                1200


                1000
Carbon Stored




                 800


                 600


                 400


                 200


                   0
                       No-Till Switchgrass   No-Till Corn   Plow-Tilled Corn
       Cellulosic Ethanol (the next generation) will provide
  21 billion gal per yr (2007 EISA) beginning in 2016, but how?


• Biological – Homogeneous feedstock




• Thermochemical – Mixed feedstock




                              Slide courtesy of R. Cruse, ISU, 2007
Cellulosic ethanol using corn fodder? Handling, storage,
transportation and soil erosion issues…
Mixed prairie grasses for cellulose give higher yields w/ lower
inputs than monocultures like switch grass (Tilman, 2006)
Woody Biomass like poplars could be utilized, too
                         Conclusions


• Biomass is likely to grow in its use as a feedstock for
  production of renewable energy
   – Direct burning of biomass and municipal waste  energy
   – Biogas from landfills and manure
   – Biofuels will go from corn to cellulose in 5-10 years
   – Synthetic fuels may increase after that and production of
     hydrogen from biomass as a storable renewable fuel

• Places like Iowa will benefit from biomass fuels