Multi-Use Crops and Botanochemical Production - ACS Symposium

6 Multi-Use Crops and Botanochemical Production M. O. BAGBY, R. A. BUCHANAN, and F. H . OTEY

Downloaded by AUBURN UNIV on November 19, 2016 | http://pubs.acs.org Publication Date: January 29, 1981 | doi: 10.1021/bk-1981-0144.ch006

Northern Regional Research Center, S E A / A R , USDA, 1815 North University Avenue, Peoria, IL 61604

Scripture tells that early man recognized and used petroleum in the form of asphalts, tars, and oils. Coal gained acceptance in the 16th century, and its use continued to expand into the 20th century. However, before the petroleum industry began to take shape in the mid-19th century and virtually exploded onto the industrial scene with invention of the internal combustion engine, man relied principally on renewable materials for his energy, oil, and hydrocarbon resources. Today, with the decline in readily removable petroleum and rising costs of liquid fuels and chemical feedstocks, man is developing a renewed awareness of the potential value of underutilized and diverse plant species. Numerous investigators have advanced ideas for development of energy and chemical resources from plants. The energy plantation has been analyzed in detail by Szego and Kemp (1) and Goldstein (2). Concepts of "petrol plantations" have been described by Calvin (3,4), and companies such as Diamond Shamrock (5) and Goodyear (6) are investigating their potential. "Integrated adaptive agricultural systems" have been discussed by Lipinsky (7), and Buchanan and Otey have advanced their "multi-use botanochemical systems" (8). In all of these proposals, entire above-ground material is to be harvested and used. And, in the most advanced schemes, fuel and chemical feedstock production is integrated with production of food and feed.

This chapter not subject to U.S. copyright. Published 1981 American Chemical Society

Klass; Biomass as a Nonfossil Fuel Source ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

126

BIOMASS AS A N O N F O S S I L F U E L

SOURCE

If f u e l is t o b e c o m e a m a j o r f a r m p r o d u c t n e w a g r i c u l t u r a l practices a n d s y s t e m s s h o u l d m a x i m i z e e n e r g y p r o d u c t per u n i t e n e r g y input. L o w - e n e r g y c r o p p r o d u c t i o n a n d e n e r g y - e f f i c i e n t processing m e t h o d s a n d h a n d l i n g t e c h n i q u e s m u s t be c o m p o n e n t s for f u t u r e a g r i c u l t u r a l scenarios. S u c h a s c h e m e has been p r o p o s e d b y B u c h a n a n a n d O t e y (8).


B O T A N O C H E M I C A L SCREENING T h e p l a n t k i n g d o m provides a reservoir of 2 5 0 , 0 0 0 t o 3 0 0 , 0 0 0 k n o w n plant species. Fewer t h a n 0 . 1 % have e n j o y e d a n y s i g n i f i c a n t c o m m e r c i a l r e c o g n i t i o n in t h e w o r l d . From t h i s w e a l t h of p l a n t resources, w e a n t i c i p a t e t h a t n e w sources of e n e r g y - p r o d u c i n g p l a n t s c o u l d be i d e n t i f i e d a n d e x p l o i t e d . O i l - a n d h y d r o c a r b o n - p r o d u c i n g p l a n t s are especially a t t r a c t i v e as f u t u r e e n e r g y a n d c h e m i c a l resources. Plants already s u p p l y several p r o d u c t s c o m p e t i t i v e w i t h s y n t h e t i c p e t r o c h e m i c a l s . These p r o d u c t s i n c l u d e tall o i l , naval stores, seed oils, a n d p l a n t oils. For t h i s d i s c u s s i o n , w e refer t o s u c h p r o d u c t s c o l l e c t i v e l y as oils a n d h y d r o c a r b o n s . For m a n y years, t h e U.S. D e p a r t m e n t of A g r i c u l t u r e has a c t i v e l y p u r s u e d a m u l t i - d i s c i p l i n e d a p p r o a c h t o i d e n t i f y a n d establish n e w crops as r e n e w a b l e resources (9). Patterned after t h e D e p a r t m e n t ' s p r o g r a m t o i d e n t i f y a n n u a l l y r e n e w a b l e f i b r o u s plants t h a t c o u l d be c u l t i v a t e d f o r p a p e r m a k i n g 0 0 ) , an a n a l y t i c a l s c r e e n i n g p r o g r a m w a s i n s t i t u t e d in 1 9 7 4 t o i d e n t i f y a n d evaluate species as sources of m u l t i - u s e o i l - a n d h y d r o c a r b o n - p r o d u c i n g crops for f o o d material a n d e n e r g y p r o d u c t i o n ( V L 1 2 ) . T h e m u l t i - u s e c o n c e p t requires p l a n t breeders a n d a g r o n o m i s t s t o deal w i t h a v a r i e t y of n e w c r o p s , each y i e l d i n g several different p r o d u c t s of v a r y i n g e c o n o m i c value. In s c r e e n i n g p l a n t species as p o t e n t i a l c o r p s , a r a t i n g s y s t e m w a s e m p l o y e d t h a t e m p h a s i z e d p o t e n t i a l e c o n o m y of p l a n t p r o d u c t i o n , t o t a l biomass y i e l d , a n d oil a n d h y d r o c a r b o n c o n t e n t (8). S u b s e q u e n t l y , all c a n d i d a t e s w e r e ranked by t h i s r a t i n g s y s t e m . It s h o u l d be e m p h a s i z e d t h a t v i g o r o u s perennials w e r e g i v e n preference over a n n u a l s , w i t h t h e c o n c e p t t h a t seed-bed p r e p a r a t i o n w o u l d be i n f r e q u e n t for perennials. Data f o r over 3 0 0 species have been a c c u m u l a t e d , a n d a b o u t 4 0 species have been i d e n t i f i e d t h a t have s u f f i c i e n t p o t e n t i a l t o m e r i t f u r t h e r c o n s i d e r a t i o n . Nearly all of these species are b e i n g f u r t h e r i n v e s t i g a t e d by U S D A plant scientists; meanwhile, the screening program continues. In t h e o r i g i n a l scenario, p o t e n t i a l r u b b e r c r o p s w e r e c o n s i d e r e d . Since t h e n , it w a s d e c i d e d t o d e v e l o p g u a y u l e (Parthenium argentatum) as a d o m e s t i c source for natural r u b b e r (K3). T h e U.S. r u b b e r m a r k e t can p o t e n t i a l l y be s u p plied by g u a y u l e g r o w n in t h e s o u t h w e s t . T h u s , barring d i s c o v e r y of an


6.

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127

Botanochemical Production


exceptional candidate, that decision preempts development of other rubber crops. H o w e v e r , several p o t e n t i a l b o t a n o c h e m i c a l c r o p species p r o d u c e l o w m o l e c u l a r - w e i g h t soluble rubbers 0 4 ) t h a t w o u l d be v a l u a b l e as a h y d r o c a r bon c o m p o n e n t o f w h o l e - p l a n t oils. Our a n a l y t i c a l p r o c e d u r e consists o f s t e p w i s e a c e t o n e e x t r a c t i o n f o l l o w e d b y c y c l o h e x a n e . S u b s e q u e n t l y , t h e a c e t o n e - s o l u b l e f r a c t i o n is p a r t i o n e d b e t w e e n h e x a n e / a q u e o u s e t h a n o l (12.15), a n d t h e soluble c o m p o n e n t s are freed o f solvents a n d d e t e r m i n e d g r a v i m e t r i c a l l y . For lack of specific n o m e n c l a t u r e , t h e b o t a n o c h e m i c a l s isolated b y t h i s t e c h n i q u e have been referred t o as " w h o l e plant o i l , " " p o l y p h e n o l , " a n d " p o l y m e r i c h y d r o c a r b o n . " A c t u a l l y , c o m p o n e n t s f r o m t h e s e e x t r a c t s need t o be f u r t h e r characterized. H o w e v e r , p e t r o l e u m refinery processes m a y be s u f f i c i e n t l y insensitive t o a l l o w use of c a r b o n - h y d r o g e n rich c o m p o u n d s represented b y a broad s p e c t r u m o f s t r u c t u r e s . For e x a m p l e , c o n s i d e r t h e diverse c h e m i c a l s r a n g i n g f r o m m e t h a n o l t o natural r u b b e r w h i c h have been c o n v e r t e d t o gasoline (16). T h u s , c h e m i c a l species m a y be i m p o r t a n t if c h e m i c a l i n t e r m e d i a t e s are b e i n g g e n e r a t e d b u t m a y be n o n c o n s e q u e n t i a l f o r p r o d u c t i o n of fuels, solvents, carbon black, a n d o t h e r basic c h e m i c a l s . P R O M I S I N G S P E C I E S FOR W H O L E P L A N T U S E Plant f a m i l i e s f r o m w h i c h m o r e t h a n o n e p r o m i s i n g species has been i d e n tified t h u s far are A n a c a r d i a c e a e , A s c l e p i a d a c e a e , Coprifoliaceae. C o m positae. Euphorbiaceae. a n d Labiatae. H o w e v e r , representative species f r o m t e n o t h e r f a m i l i e s have been i d e n t i f i e d as h a v i n g s u f f i c i e n t p o t e n t i a l t o m e r i t f u r t h e r c o n s i d e r a t i o n . U n d o u b t e d l y , t h e s a m p l e base is t o o i n c o m p l e t e t o establish a n y t r e n d s . Crop ratings a n d p r o x i m a t e c o m p o s i t i o n of p r o m i s i n g species are s u m marized in Table I. Species c o n t a i n i n g t h e greater a m o u n t o f o i l , all e x c e e d i n g 6%, w e r e Ambrosia trifida. Campanula americana, Asclepias hirtella. a n d t h e t h r e e Euphorbiaceae. Those w i t h t h e m o s t a b u n d a n t p o l y m e r i c h y d r o c a r b o n , e x c e e d i n g 2%, w e r e Asclepias subulata. A. tuberosa Crystostegia grandiflora, Cacalia atriplicifolia. Parthenium argentatum. Elaegnus multiflora, and Agropyron repens. Seven species h a d m o r e t h a n 15% o f t h e polar fract i o n labelled p o l y p h e n o l , i.e., Acer saccharinum. Rhus glabra, Lonicera tatarica. Elaeagnus multiflora, Xylococcus bicolor, Teucrium canadensis. a n d Prunus americanus. A n d o n e species, Vernonia altissima, had m o r e t h a n 2 0 % o f apparent p r o t e i n . f

Protein c o n t e n t s are c a l c u l a t e d f r o m Kjeldahl n i t r o g e n values b y a p p l y i n g t h e f a c t o r 6.25 as t h e n i t r o g e n e q u i v a l e n t f o r p r o t e i n . H o w e v e r , t h e nature of t h e n i t r o g e n o u s c o m p o n e n t s m u s t b e elaborated b y f u r t h e r research. In a d i s c u s -


128


SOURCE

sion of leafy p l a n t s as p r o t e i n resources, Kohler et al. r e m i n d us t h a t in a d d i t i o n t o desirable n u t r i e n t s , m o s t p l a n t s c o n t a i n c o m p o u n d s w h i c h , if not a p p r o p r i a t e l y d e a l t w i t h , m a y be d e l e t e r i o u s t o a n i m a l s (17). T h e y also d i s cuss several p r o c e s s i n g s c h e m e s w h i c h m a y p r o v i d e i n s i g h t s i n t o p r o c e s s i n g plants identified during the screening program.


P L A N T OIL A N D H Y D R O C A R B O N - P R O D U C I N G SPECIES D u r i n g W o r l d W a r II, Parthenium argentatum, Cryptostegia grand/flora. Crysothamnus nauseosus, a n d Solidago leavenworthii were given considerable a t t e n t i o n as possible d o m e s t i c r u b b e r sources (18). P. argentatum is u n d e r g o i n g v i g o r o u s r e i n v e s t i g a t i o n (19). Taraxacum kok-sagbyz (Russian d a n d e l i o n ) , a l t h o u g h n o t listed in Table I p r i n c i p a l l y because of b o t a n i c a l c h a r a c t e r i s t i c s , w a s also a s t r o n g c a n d i d a t e as a p o t e n t i a l r u b b e r c r o p d u r i n g t h e 1940's (20). See Table II f o r c o m p a r i s o n s of Hevea brasiliensis rubber m o l e c u l a r w e i g h t s w i t h t h o s e of species i d e n t i f i e d b y S w a n s o n , B u c h a n a n , a n d O t e y (14). Relatively f e w p l a n t species have been p r o p o s e d as p o t e n t i a l U.S. oil a n d h y d r o c a r b o n crops. A s p r e v i o u s l y s t a t e d , t h e r e is c o n s i d e r a b l e c u r r e n t interest in g u a y u l e for p r o d u c t i o n of n a t u r a l rubber. Rubber is a pure h y d r o c a r b o n easily d e p o l y m e r i z e d i n t o isoprene or r e f o r m e d i n t o gasoline (16). For t h i s use, l o w m o l e c u l a r w e i g h t m a y be an a d v a n t a g e ; t h e p o l y i s o p r e n e p r o b a b l y is best e x t r a c t e d as a h y d r o c a r b o n c o m p o n e n t of a w h o l e - p l a n t oil. A m i l k w e e d . Asclepias speciosa. is b e i n g g r o w n e x p e r i m e n t a l l y in U t a h . U S D A a g r o n o m i s t s are s t u d y i n g t h e c o m m o n m i l k w e e d . Asclepias syriaca. a n d a f e w r u b b e r - a n d o i l - p r o d u c i n g species in o t h e r plant families. G u t t a has been f o u n d in several Gramineae species (2J[). A l t h o u g h these species are l o w in c o m b i n e d oil a n d h y d r o c a r b o n c o n t e n t . Elymus canadensis is b e i n g g r o w n in small p l o t s t o t e s t its response t o p l a n t g r o w t h s t i m u lants, a n d t h e g e n e t i c v a r i a b i l i t y of Agropyron repens is b e i n g e v a l u a t e d . A f e w Euphorbiaceae have been s u g g e s t e d as crops for p r o d u c t i o n of a w h o l e - p l a n t oil l o w in p o l y i s o p r e n e c o n t e n t . Calvin has d r a w n particular a t t e n t i o n t o Euphorbia lathyrus a n d Euphorbia tirucalli. species t h a t are a c c u s t o m e d t o arid lands, a n d has s u g g e s t e d t h a t A s c l e p i a d a c e a e a n d Euphorbiaceae deserve increased a t t e n t i o n because t h e y generally c o n t a i n o i l - a n d h y d r o c a r b o n - r i c h latexes. H e x a n e - e x t r a c t a b l e material f r o m £ lathyrus. r e p r e s e n t i n g 4 - 5 % of p l a n t d r y w e i g h t , has been r e p o r t e d t o have a h e a t i n g value of ~~ 1 8 . 0 0 0 B t u / l b (22). This material consists a l m o s t entirely



Campanula

americana

Campanulaceae

Lonicera tatarica Sambucus canadensis Symphoricarpos orbiculatus Trios teum perfoliatum

Caprifoliaceae

Asclepias hirtella Asclepias incarnate Asclepias subulata Asclepias syriaca Asclepias tuberose Cryptostegia grandiflora

Asclepiadaceae

Apocynum androsaemitolium

Apocynaceae

Tall bellflower

9.7

5.9 7.1

Coral berry Tinker's weed

6.2

11.1 14.2

15.8 6.6

—

— 10.2 6.5

12.3

— 8.0

4.4 11.5

7.8

20.2 10.5

19.8

Polyphenol Fraction,

12.3 8.1

—

14.2 11.0

Red tatarion honeysuckle Common elder

Green milkweed Swamp milkweed Desert milkweed Common milkweed Butterfly-weed Madagascar rubber vine

17.0

Smooth sumac Laurel sumac

Spreading dogbane

7.1 8.1

Silver maple

Aceraceae Acer saccharinum Anacardiaceae

Rhus glabra Rhus laurina

16.3

Common Name

Family-Genus-Species

Crude Protein,

6.5

2.3 2.6

3.4 2.2

6 7

cd

7.7 3.0 11.4 4.8 3.1 cd

3.0

5.9 5.5

2.4

Oil Fraction, % b

c

0.99

0.81 1.43

1.77 0.52

c

0.49 1.87 2.95 1.54 2.84 2.19

0.50

0.21 1.44

0.39

R.W

R R

R R

R R R R R R

R.W

W W

—

10

10 10

9 10

10 10 8 9 9 10

10

10 8

9

Polymeric Hydrocarbons Crop Type Ratin %

Table I. COMPOSITION AND CROP RATING OF REPRESENTATIVE BOTANOCHEMICAL-PRODUCING SPECIES"


VO

to

£

H

>< m

ON


Compositae Ambrosia trifida Cacalia atriplicifolia Chrysothamnus nauseosus Cirsium discolor Eupatorium aitissimum Helianthus grosseserratus Parthanium agentatum Rudbeckia subtomentosa Silphium integhfolium Silphium laciniatum Silphium tarbinthinacaum Solidago graminifolia Solidago laavenworthii Solidago ohioensis Solidago rig/da Sonchus arvensis Varonia altissima Veronica fasciculate aeagnaceae Elaagnus multiflora icaceae Xylococus bicolor E/ymus canadensis 18.6 5.5

7.2 7.0

Canada wild rye

—

18.9

11.9

Cherry elaeagnus

e

e

6.3 13.4 8.9 8.6 6.8 11.0 6.9 8.4

4.5 5.6 12.9 5.8 4.9 9.3 21.6 11.4

Prairie dock Grass-leaved goldenrod Edison's goldenrod Ohio goldenrod Stiff goldenrod Sow thistle Tall iron weed Ironweed

e

e

2.03 1.08 1.35

5.4 1.7

e

e

e

e

0.94 1.51 1.52 0.54 1.48 0.72 0.38 0.39 2.3

2.8 2.6 5.0 2.5 2.4 5.3 3.1 5.4

e

0.76 4.98 1.22 0.79 0.75

2.3 4.4 2.4 2.8 3.3

8.8 18.1 5.9 6.2 9.8

Cut-leaf sunflower Guayule Sweet coneflower Rosin weed Compass plant

9.2 7.7 7.8 7.0 8.1

5.9 8.6

3.9 10.8

—

—

0.60 3.46 1.67 0.40 0.56

4.4 9.4

11.4 11.7

Giant ragweed Pale Indian-plantain Rabbitbrush Field thistle Tall boneset

8.3 3.4 11.5 * 5.8 5.9 e



dentata lathyris pulcherrima

albidum e

17.3

12.4

15.5

8.9

13.3 14.3

12.2

19.4 12.7 16.4

V.

e

18.5

12.8

5.9

14.4

8.0 16.7

4.6

4.1 7.6 6.4

·/.

Polyphenol Fraction,

e

4.6

3.4

3.4

5.7

2.2 2.7

2.4

11.2 9.9 6.3

%

Oil Fraction,

Literature values.

Also contains Polyphenol fraction.

Values are moisture free but are not corrected for ash.

d

β

Identified by infrared G — gutta, R — rubber. W — wax.

Values are moisture and ash free; crude protein is calculated from Kjeldahl nitrogen with the factor 6.25.

Wild plum

New Jersey tea

Pokeweed

Sassafras

Mountain mint American germander

Quackgrass

Cut-leaf spurge Mole plant Poinsettia

Common Name

c

8

americanus

americana

Prunus americanus

Rosaceae

Ceanothus

Rhamnaceae

Phytolacca

Phytolaccaceae

Sassafras

Lauraceae

Pycnanthamum incanum Taucrium canadensis

Labiatae

Agropyron rapens

Gramineae

Euphorbia Euphorbia Euphorbia

Euphorbiaceae

Family-Genus-Species

Crude Protein,

e

0.20

0.67

0.17

0.23

1.36 1.44

1.95

0.20 0.40 0.66

%

Polymeric Hydrocarbons b

-

W

—

W

R R

G

— — w

10

10

10

10

10 10

10

— 9 10

Crop Type Ratin

Table I. COMPOSITION AND CROP RATING OF REPRESENTATIVE BOTANOCHEMICAL-PRODUCING SPECIES" (Continued)


132

BIOMASS AS A NONFOSSIL

FUEL

SOURCE


Table II. MOLECULAR WEIGHT OF NATURAL RUBBERS RELATIVE TO HEVEA BRASIUENSIS RUBBER Species

Common Name

Ratio

Hevea brasiliensis Mull. arg. Parthenium argentatum A. Gray Pycnanthemum incanum (L.) Michx. Lamiastrum galaobdolon (L) Ehrend. and Polatsch. Monarda fistulosa L. Varonia fasciculate Michx. Symphoricarpos orbicu/atus Moench Sonchus arvensis L. Xylcoccus bicolor Nutt. Melissa officinalis L Silphium integhfolium Michx. Helianthus hirsutus Raf. Cirsium vu/gare (Savy) Ten. Cacalia atriplicifoliaJL. Euphorbia glyptosparma Engelm. Monarda didyma L Lonicera tatarica Triostaum perfoliatum L. Solidago altissima L Cirsium discolor (Muhl.) Sprang. Solidago graminifolia (L) Salisb. Apocynum cannabinum L. Polymnia canadensis L. Gnalphalium obtusifo/ium L. Silphium terebinthinaceum Jacq Euphorbia pulcherrima Asclepias incarnate L Grindelia squarrosa (Pursh.) Duval. Veronia altissima Nutt. Solidago rigida L. Euphorbia comitate L. Helianthus grossesserratus Martens Elaegnus multiflora Thunb. Rudbeckia laciniata L. Pycnathemum virginianum (L.) Durand & Jackson Campsis radicans (L.) Seem, ex Bur. Chanopodium album L. Monarda punctata L. Apocynum androsaamifolium L Asclepias tuberose L Nepeta catena L Teuchum canadense L. Solidago ohioensis Riddel 1 Artemisia vulgaris L 4 s f e r /aev/s L. Asclepias syriaca L Artemisia abrotanum L Campanula americana L Centauœa vochinesis Bernh.

Rubber tree Guayule Mountain mint Yellow archangel Wild bergamont Iron weed Coral berry Sow thistle Two-color wood berry Balm Rosinweed Hirsute sunflower Bull thistle Pale Indian plantain Ridgeseed Euphorbia Oswega tea Tartarian honeysuckle Tinker's weed Tall goldenrod Field thistle Grass-leafed goldenrod Indian hemp Leafy cup Fragrant cudweed Prairie dock Poinsettia Swamp milkweed Tarweed Iron weed Stiff goldenrod Flowering spurge Sawtooth sunflower Cherry Elaegnus Sweet coneflower Mountain mint Trumpet creeper Lambsquarter Horsemint Spreading dogbane Butterfly weed Catnip American germander Ohio goldenrod Common mugwort Smooth aster Common milkweed Southernwood Tall bellflower Knapweed

1.00 0.98 0.38 0.32 0.32 0.32 0.28 0.25 0.25 0.24 0.22 0.21 0.20 0.20 0.20 0.20 0.19 0.18 0.18 0.18 0.18 0.16 0.16 0.16 0.15 0.15 0.14 0.13 0.13 0.12 0.12 0.12 0.12 0.12 0.11 0.11 0.11 0.11 0.11 0.10 0.10 0.10 0.10 0.10 0.10 0.09 0.09 0.09 0.08



6.

BAGBY ET A L .


133

Table II. MOLECULAR WEIGHT OF NATURAL RUBBERS RELATIVE TO HEVEA BRASIUENSIS RUBBER (Continued)

Physostegia virginiana (L.) Benth. Verbena urticifolia L. Euphorbia cyparissias L. Ocimum basilicum L. Asclepias hirtella (Pennell Woodson) Achillea millefolium L. Phyla lanceolate (Michx) Greene Gaura biennis L.

Obedient plant White vervain Cypress spurge Purple basil Milkweed Yarrow Frog fruit Gaura


0.08 0.08 0.08 0.08 0.08 0.07 0.07 0.07

134


SOURCE

of p o l y c y c l i c t r i t e r p e n o i d s . £ lathyris is b e i n g f u r t h e r e v a l u a t e d at t h e University of A r i z o n a (5). a n d U S D A is e v a l u a t i n g £ pulcherrima a n d several o t h e r Euphorbiaceae. D u r i n g t h e s u m m e r of 1 9 7 9 . U S D A m a d e a special effort t o c o l l e c t L e g u m i n o s a e species. A n d in S e p t e m b e r 1 9 7 9 . Calvin d r e w a t t e n t i o n t o t h e L e g u m i n o s a e Copaifera langsdorfii w h i c h , he o b s e r v e d , p r o d u c e s v i r t u a l l y p u r e diesel fuel (23).


POLYPHENOLS A N D T A N N I N S T h e rather s i m p l e s o l v e n t c l a s s i f i c a t i o n s c h e m e s y i e l d c o m p l e x f r a c t i o n s of b o t a n o c h e m i c a l s . Their d e t a i l e d c o m p o s i t i o n d e p e n d s not o n l y o n t h e species b u t also o n m a t u r i t y of t h e p l a n t a n d t h e m e t h o d of e x t r a c t i o n (15.22). T h e polar f r a c t i o n isolated by a c e t o n e e x t r a c t i o n a n d readily soluble in 8 7 . 5 % a q u e o u s e t h a n o l . t e r m e d " p o l y p h e n o l " by B u c h a n a n a n d c o w o r k e r s (11.12). no d o u b t c o n s i s t s of p h e n o l i c s a n d a w i d e v a r i e t y of o t h e r s u b s t a n c e s . For p l a n t s of h i g h t a n n i n c o n t e n t , (e.g.. Rhus giaubra) t h e p o l y p h e n o l f r a c t i o n m i g h t w e l l be called t a n n i n (24) HARVESTING A N D PROCESSING S C H E M E S H a r v e s t i n g a n d p r o c e s s i n g t e c h n o l o g i e s w i l l need t o be d e v e l o p e d a n d i n d i v i d u a l l y t a i l o r e d t o each species. A m u l t i - d i s c i p l i n e d a p p r o a c h is essential t o c a p t u r e t h e f u l l p o t e n t i a l offered by t h e v a r i o u s species. W h i l e it is b e y o n d t h e s c o p e of t h i s r e v i e w t o e l a b o r a t e o n t h e m a n y facets, m a j o r areas of c o n cern are: h a r v e s t i n g m e t h o d a n d t i m i n g , h a n d l i n g , storage, a n d separation a n d recovery of materials. For e x a m p l e , see s o m e U S D A experiences w i t h t h e d e v e l o p m e n t of p r o m i s i n g n e w c r o p s c r a m b e a n d kenaf (25.26). Processing of w h o l e plant materials for oil a n d h y d r o c a r b o n has been d i s cussed by B u c h a n a n a n d O t e y (8) a n d Nivert a n d c o w o r k e r s (27). In t h e p r o cess e n v i s i o n e d , baled plant m a t e r i a l is flaked in e q u i p m e n t c o m m o n t o t h e s o y b e a n p r o c e s s i n g i n d u s t r y . T h e flakes are s u b s e q u e n t l y e x t r a c t e d b y t h e a p p r o p r i a t e s o l v e n t , perhaps b y a s e q u e n t i a l e x t r a c t i o n u s i n g several s o l vents. LIGNOCELLULOSIC RESIDUE In all p l a n t materials, t h e m a j o r c o m p o n e n t w i l l be t h e cellular l i g n o c e l l u l o s i c m a t e r i a l . Several possible uses for t h i s material exist. S o m e of t h e m o r e a t t r a c t i v e are c a t t l e f e e d ; f i b e r for p u l p , paper, a n d b o a r d ; c h e m i c a l f e e d s t o c k ; or e n e r g y (8.1JL_12). Detailed e v a l u a t i o n of t h e cellular p o r t i o n s h o u l d p r o v i d e bases for s u g g e s t i n g t h e i r m o s t a p p r o p r i a t e uses.


6.

BAGBY E T A L .


135

CONCLUSIONS Green p l a n t s are s o l a r - p o w e r e d c h e m i c a l factories t h a t c o n v e r t c a r b o n d i o x ide a n d w a t e r i n t o a v a r i e t y of e n e r g y - r i c h c o m p o u n d s . Crops c a n be d e v e l o p e d t o help p r o v i d e r e n e w a b l e sources of fuels a n d c h e m i c a l s a n d at t h e s a m e t i m e t o p r o v i d e a c o n t i n u i n g source of feed a n d f o o d . Several c a n d i dates have been i d e n t i f i e d , w h i c h c a n b e c o m e f u t u r e crops for A m e r i c a n Agriculture.


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BIOMASS AS A NONFOSSIL FUEL SOURCE


15. Buchanan, R. Α.; Otey, F. H.; Russell, C. R.; Cull, I. M. J. Am. Oil Chem. Soc. 1978, 55, 657. 16.

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Multi-Use Crops and Botanochemical Production - ACS Symposium

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