Cahen, Erice 7-2014 (J. Gressel) The Challenges for Biofuels Maybe; likely a high %, for a while...

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


Outline•Zero Generation Biofuels

•First Generation BiofuelsThe problems – food vs. fuel

•Second Generation Biofuels- Lignocellulosics for ethanol- Oils for biodiesel

•Future


Plant photosynthesisis < (<<) 1% efficient

Gust, Kramer, Moore, Moore & Vermaas, MRS Bulletin, 2008

Photosynthetic MICRO-organismscan do better, ~ 4%

The source of all biomass


Traditional biofuels

India

Africa

InefficientPollutingEnvironmentally negativeCan we do better?


OATS was traditional biofuel in temperate climate areas

Cultivated on ca. 20% of land


Oats fueled all of farming:mules, horses and laborers



•First Generation Biofuelsand the problem – food vs. fuel

•Second Generation Biofuels- Lignocellulosics for ethanol- Oils for biodiesel

•Future


Ethanol: an increasing portion of the US maize crop


Monthly production and net imports of fuel ethanol in the U.S. 1993-2012. Data from EIA


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


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


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 ?


Is there energy gain for maize (corn) grain ethanol?

(LUC)


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

on http://wws.weizmann.ac.il/AERI/presentations


Teosinte-the progenitor

Corn ca. 1492

Hybridcorn

Domestication of corn

Cahen, Erice 7-2014 (J. Gressel)David McKay SEWTHA

Comparing Potential Biofuel Crops

Power Density [W / m2 ] (cf. to Si solar panel in Kalahari desert ~ 25 Wc / m2 )

Cahen, Erice 7-2014 (J. Gressel)The Economist 2009

Comparing Potential Biofuel Crops


Calculated from Chisti, Biotech. Adv. 25:294-306, 2007


J. Goldemberg, SP

Brazil: 50% of sugar cane crop > 40% of non-diesel fuel

13.6 million (2011)

Cahen, Erice 7-2014 (J. Gressel)J. Goldemberg, SP


First generationnot sustainable in medium term



•First Generation BiofuelsThe problems – food vs. fuel

•Second Generation Biofuels use agricultural wastes lignocellulosics

- Lignocellulosics for ethanol- Oils for biodiesel- Grasses

but… such crops were not domesticated for biofuels!•Future (3d generation)


How are plants built ?HOW ARE PLANTS BUILT?

HOW ARE PLANTS BUILT?

Cahen, Erice 7-2014 (J. Gressel)© Materials Research Society 2012

Fig25_05




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


Can grasses++ be turned into fuel?


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


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


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?


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 …


Cellulosic ethanol Acid, Heat

Is this environmentally sound?


Can less heat/less acid be used if grass is modified?


Lignin

Less lignin should higher grain yieldDespite common suggestions / myth:no direct correlation between lignin and strength


The higher the lignin contentthe lower the digestibility


Solution:Modify crop for:- less ligninor- modified ligninor - more cellulose

Should reduce the acid/heat requirement,add to yield


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?


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


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.


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)

Most now agree – OK, if 20% left in field


Outline•Zero Generation Biofuels•First Generation Biofuels

The problems – food vs. fuel•Second Generation Biofuels use agricultural wastes lignocellulosics

- Lignocellulosics for ethanol- Oils for biodiesel- Grasses

•Future (3d generation)Cultivate & use biofuel-dedicated crops- perennial lignocellulosics- perennial oilseeds- ALGAE

but ….. first learn from what we are doing now


Oilseed rape is favored for temperate climes

Is it nice to the environment?Worldwide, oilseed rape emits ca. 9000 Tonnes

Before the ban Europe consumed 18,000 T CH3Br

Is “natural” CH3Br OK, but synthetic bad?Is it OK to double the area for biofuel?

*Gan, J., et al. (1998) Production of methyl bromide by terrestrial higher plants. Geophysical Research Letters 25, 3595-3598


Palm oil poor biodiesel (by transesterification*)

congeals at low temperatures

Must catalytically crack it - or mix

Needs shorter chain length- antisense elongases

Needs more mono un-saturation- engineer desaturases

Such engineering in non-cholesterogenic “palmolive” oil

*


Only by bringing genes fromelsewhere can we breach theglass ceilings


LIPIDSfatty acid chains

Cutins - polymers of short fatty acids; these are unique to plants

Triglycerides - three fatty acid chains bound to a single molecule of glycerol

Waxes - polymers of long fatty acids

Triglycerides


Biodiesel from various sources


30% oil - seeds get US$140/ton (optimistic)- fruits hand-harvested- fruits dried in the shade- seeds removed by hand

Is Jatropha real or gimmick (keep the poor poor)?


Some more info on Jatropha curcascommon plant names: Black vomit nut, Purge nut, etc.common oil names: hell oil, oleum infernale, etc.

Toxins: Curcin (a toxalbumin) - similar to ricinPhorbol esters - diterpenoids (alkaloids)

skin tumor promotersNo antidote known

See: http://www.inchem.org/documents/pims/plant/jcurc.htmJatropha poisoning resembling organophosphate intoxication Clin. Tox. 44 337,2006

Imagine releasing a transgenic crop with such components….

So, what to do with toxic byproducts?


Websites: “curcin is heat-degradable”Reference:“degradable by prolonged autoclaving”

Curcin ~ Ricinpotent toxin

(slow death marked by vomiting &diarrhea)


Castor has similar problems as JatrophaSeeds contain 0.2 to 3% ricin

1 mg/kg toxicfill car with 50 liters (13 gallons diesel)enough ricin by-product to kill 3 peopleat lowest content, 45 at highest

Ricin protein “easy” to eliminate transgenically!


Oklahoma bill against castor production & transportation proposed. Why?

Castor beans contain 50% or more oil for producing biofuels.

They also contain high levels of ricin.

Edible crop producers became concerned about ricin residues in fields, equipment, storage bins, and transportion.

Jatropha banned in Western Australiaas “toxic to man and livestock”

Approach should be to ban the toxins – and stimulate DOMESTICATION


- Short term – biofuels from food crops

- Medium term – biofuels from cellulosic wastes & algae

-Long term - … algae ??

and, very likely, successful biofuel feedstocks will be transgenic


Seambiotic (Seambiotic (ω3), ), Transalgae (fishmeal) Transalgae (fishmeal)

Nature Beta Technol. (β-carotene)

Cahen, Erice 7-2014 (J. Gressel) The Challenges for Biofuels Maybe; likely a high %, for a while...

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