Cahen, Erice 7-2014 (J. Gressel) The Challenges for Biofuels Maybe; likely a high %, for a while Maybe by using algae, waste or marginal land ? Lower than just fossil fuel;more sustainable 1- Food vs.Fuel dilemma 2- Can we produce the amounts needed? 3- Environmental impact 4- EROI Try to be honest Jonathan Gressel Avi Levy & Biofuel consortium Dept. of Plant Sciences
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Cahen, Erice 7-2014 (J. Gressel) The Challenges for Biofuels Maybe; likely a high %, for a while Maybe by using algae, waste or marginal land ? Lower than.
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Cahen, Erice 7-2014 (J. Gressel)
The Challenges for Biofuels
Maybe; likely a high %, for a while
Maybe by using algae, waste or marginal land ?
Lower than just fossil fuel;more sustainable
1- Food vs.Fuel dilemma
2- Can we produce the amounts needed?
3- Environmental impact
4- EROI
Try to be honest
Jonathan GresselAvi Levy & Biofuel consortiumDept. of Plant Sciences
Cahen, Erice 7-2014 (J. Gressel)
Outline•Zero Generation Biofuels
•First Generation BiofuelsThe problems – food vs. fuel
•Second Generation Biofuels- Lignocellulosics for ethanol- Oils for biodiesel
•Future
Cahen, Erice 7-2014 (J. Gressel)
Plant photosynthesisis < (<<) 1% efficient
Gust, Kramer, Moore, Moore & Vermaas, MRS Bulletin, 2008
Photosynthetic MICRO-organismscan do better, ~ 4%
The source of all biomass
Cahen, Erice 7-2014 (J. Gressel)
Traditional biofuels
India
Africa
InefficientPollutingEnvironmentally negativeCan we do better?
Cahen, Erice 7-2014 (J. Gressel)
OATS was traditional biofuel in temperate climate areas
Cultivated on ca. 20% of land
Cahen, Erice 7-2014 (J. Gressel)
Oats fueled all of farming:mules, horses and laborers
Cahen, Erice 7-2014 (J. Gressel)
Outline•Zero Generation Biofuels
•First Generation Biofuelsand the problem – food vs. fuel
•Second Generation Biofuels- Lignocellulosics for ethanol- Oils for biodiesel
•Future
Cahen, Erice 7-2014 (J. Gressel)
Ethanol: an increasing portion of the US maize crop
Cahen, Erice 7-2014 (J. Gressel)
Monthly production and net imports of fuel ethanol in the U.S. 1993-2012. Data from EIA
Cahen, Erice 7-2014 (J. Gressel)
What are world implications?
Biofuels: Good News/Bad News to developing world
Bad news: no more cheap/free grain for food security in time of famine
Good news: No more “dumping” subsidized grain, sold below production costs
Developing world farmers can now competeand easily triple yields
Cahen, Erice 7-2014 (J. Gressel)
Biofuels: Good News/Bad News to developed world farmers
Good news to grain farmers - prices stable
Bad news to dairy/beef/chicken/hog farmers
- grain prices high…
Bad news to consumers – do not lower fuel prices, higher food costs
Cahen, Erice 7-2014 (J. Gressel)
Ethical question Europe (Japan) must ask:Is it right to support eliminating rainforests and jungles elsewhere, for Europe (Japan) to import soy/palm oil for biodiesel so that Europe (Japan) can preserve “Landscapes”?
Ethical question all must ask:Is it ethical to drive a big car on biofuel, considering effect on agriculture ?
Cahen, Erice 7-2014 (J. Gressel)
Is there energy gain for maize (corn) grain ethanol?
(LUC)
Cahen, Erice 7-2014 (J. Gressel)
All depends on how we do the calculationsMost calculations do not include: - accounting of byproducts - recent advances - appropriate “systems boundaries”
Dale does calculations, based on ability to replace petroleum or on greenhouse gases produced per km driven;Pimentel & Patzek strongly disagree(you can do the math yourself, using the student ppt* on it)* See Total Energy Analysis of ethanol production from corn
The plant cell wall is built ofCellulose, hemicellulose and lignin—the most abundant polymers on the planet—sources of
sugars for fermentation
The plant cell wall is built ofCellulose, hemicellulose and lignin—the most abundant polymers on the planet—sources of
sugars for fermentation
Cahen, Erice 7-2014 (J. Gressel)
Can grasses++ be turned into fuel?
Cahen, Erice 7-2014 (J. Gressel)
Switchgrass does not defy the law of conservation of matter; it grows best with …
water nitrogen fertilizer
Data of Lee et al. and Muir et al, collated in Gressel,“Genetic Glass Ceilings, Hopkins, 2007
Cahen, Erice 7-2014 (J. Gressel)
The non-degraded switchgrass residue is burnt energy for process
Contains 5-10% ash, > 60% of ash (=silica)On burning releases 50% more non-precipitable silica than coal*
Same with sugarcane bagasse/other grasses
Rice has highest silica content of grassesHow dangerous is burning rice straw?
*Blevins, L.G., and Cauley, T.H. (2005) Fine particulate formation during switchgrass/coal co-firing. Journal of Engineering for Gas Turbines and Power-Transactions of the ASME 127, 457-463
Cahen, Erice 7-2014 (J. Gressel)
Silicon not a required element for plantssmall amounts may be usefulbut not the high amounts in many
grasses,including sugarcane
Silicon transporters being discovered in plants use antisense RNA or RNA-interference to lower their levels?
Cahen, Erice 7-2014 (J. Gressel)
Process:Heat + acid pre-treatment (delignification)Enzymatically digest cellulose to sugarsFerment sugars to ethanol
But half of cellulose is unavailable 208 kg ethanol/tonne
straw
Claim: with present technology - Canadian wheat straw could provide ethanol for almost all Canadian automobiles; maybe, but …
Cahen, Erice 7-2014 (J. Gressel)
Cellulosic ethanol Acid, Heat
Is this environmentally sound?
Cahen, Erice 7-2014 (J. Gressel)
Can less heat/less acid be used if grass is modified?
Cahen, Erice 7-2014 (J. Gressel)
Lignin
Less lignin should higher grain yieldDespite common suggestions / myth:no direct correlation between lignin and strength
Cahen, Erice 7-2014 (J. Gressel)
The higher the lignin contentthe lower the digestibility
Cahen, Erice 7-2014 (J. Gressel)
Solution:Modify crop for:- less ligninor- modified ligninor - more cellulose
Should reduce the acid/heat requirement,add to yield
Cahen, Erice 7-2014 (J. Gressel)
Wheat straw as feedstock for biofuelWheat straw as feedstock for biofuel
• Abundant ~ 0.7 GTonne/year• Cheap• Does not compete with food• 1 GT could provide 10s % USA fuel/yr?
Cahen, Erice 7-2014 (J. Gressel)
Why not use 2 GTonne of free waste biomass ?
With switchgrass and miscanthus, land must be bought, dedicated to cultivation, watered, fertilized and harvested.Straw is available “free” - a by-product of grain production
Cahen, Erice 7-2014 (J. Gressel)
Straw has –ve economic/environmental value
- harbors pathogens if not burnt- requires fungicides on next crop - releases CO2 when burnt - binds nutrients while biodegrading
requires more fertilizer - pollution
-Despite being ~ 70% carbohydrate, straw has relatively low value - as animal feed (less than half
digested) or - as bioethanol source.
Cahen, Erice 7-2014 (J. Gressel)
Is using straw waste sustainable?
Soil scientists used to say “no!” because need organic matter in soil(but straw used to be burnt in Europe)