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FEMS Microbiology Reviews 103 (1992) 355-364 © 1992 Federation of European Microbiological Societies 0168-6445/92/$15.00 Published by Elsevier

355

FEMSRE 00259

M. E g g e r s d o r f e r , J. M e y e r a n d P. E c k e s BASF Aktiengesellschaft, Ludwigshafen, FRG

Key words: Renewable resources; Non-food materials

1. I N T R O D U C T I O N The use of renewable resources for non-food materials is a topic under heated discussion in various fields (Fig. 1). The reasons for the public discussion are concerns about pollution of the environment, CO 2 emissions, limited petrochemical reserves, and agricultural production surpluses. Renewable resources are a source of energy, and a feedstock for fuel or chemical reactions. They seem to be intrinsically safe and clean, and are regarded as unlimitedly available. The expectations of the public are high and opinions are formed in an emotionally charged atmosphere. As a matter of fact fossil raw materials are used as the main source for energy supply in the range of about 7 - 8 billion tons oil e q u i v a l e n t / year. The world consumption of energy is about 3250 million tons of oil, 3430 million tons of coal and 1900 billion m 3 of natural gas (Fig. 2). On the other hand, biomass production is about 170000 million tons a year. Theoretically this biomass amount would be enough to replace fossil fuels completely. However, realistically only

Correspondence to: M. Eggersdorfer, sellschaft, W-7600 Ludwigshafen, FRG.

BASF

Aktienge-

3% or about 6000 million tons of plant material can in fact be cultivated, harvested and processed. This amount includes about 2000 million tons of wood, 1800 million tons of grain and about 2000 million tons of oil seeds, sugar cane, sugltr beet, fruits, beets and so on. This figure comprises the food and non-food sectors. As shown by the total-use figures, there would not be enough renewable resources even if they were all used exclusively to replace fossil f~els. Replacement of fossil fuels by plants will not be an objective at all in the near future. Let us have a more detailed look at what our resources are used for today. The energy sector consumes large volumes of fossil resources. Most renewable resources go into nutrition. To put this in perspective it is essential to look at the total figures for the consumption of fossil and renewable resources. Figures are available for Germany. Figure 3 shows that about 93% of West German consumption of fossil resources goes on energy generation and only 7% is used in the chemistry sector. Energy is consumed for heating and by power stations and traffic. The distribution of uses of renewable resources is similar. About 97% of agricultural production goes into the nutrition sector and only

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Use of renewable resources for non-food materials

356

Neue Chance ffir die Landwirtsehaft?

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D e s V e r k e h r s m i n i s t e r s Raps-Idee: H i i b s c h , a b e t u n b e z a h l b a r

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Papieraus Heu, Schnapsglaseraus Ro;;:n~$/$

,,Hoffnungen aid Rohstoff Flachs wie Seffenblasegeplatzt" Fig. I. Selectionof newspaper headlines.

about 3% is processed into non-food materials, including chemicals. Worldwide this is equivalent to about 45 million tons of renewable resources. A simple calculation demonstrates the influence Renewable Resources

Fossil R e s o u r c e s

Total use. 6000 mill. tons / a

Total use. 7300 mill. tons OE* / a

on agricultural surplus reduction. Let us imagine a doubling in the use of renewable resources in the chemistry field. This would increase the cultiPercentage consumption of fossil resources and agricultural products by the chemical i n d u s t r y -

~

energy93%

fossilresources

wo¢

WaStGermann~m~alod con,~mm~o,)

Oilseeds Sugar-cane and Beets

Natural gas

agriculture

~""""..... ~

~

j~

chemcalindustry7%

nutritionsector97%

Fruits, Roots,Beets

Totalavailable: 170,000mill.tons/a

Totalavailable: 853.000mill.tonscoal 120.000mill.magus 135.000mill.tonsoil * Oil equivalents Fig. 2. Figures for renewable and fossil resources.

~ase~,O~w~Gend~mN~,~pl e. x c l u d ~

no. . . . ,ritionsector 3°/. (incl.chemicalindustry)

Fig. 3. Figures for the consumption of fossil and renewable

resources.

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Auf der Suche nach wirtscllaftlicn unu 6kologisch akzeptablen Technolgien

357

vation of farmland in Germany for chemical purposes to about 400000 hectares. However, in Germany alone there is an excess of 2-3 million hectares of farmland no longer needed for nutrition but which is usable for non-food materials. This simple calculation indicates that the chemi-

cal industry cannot alone contribute to any significant reduction in German or European agricultural production surpluses. However, this could be possible in the energy field, as will be discussed later. With these arguments in mind the main appli-

Million tons oil equivalent (OE) 8750

/_..

7500 6250. 5000 3750

O|1

o

1975

80

85

1990

b

Consumption of oil in OECD countries

in non - OECD countries Million tons

Million tons

750

ica

Australia 5OO Lsla

OECD Europe

250

North A m e r i c a

. . . . .

~97s

laso

lm

laeo

0

lo7s

leao

leas

laeo

Fig. 4. a. Development of global energy demand, b. Comparison of oil consumption in O E C D and non-OECD countries.

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Development of global energy demand

358

-

2. R E N E W A B L E R E S O U R C E S IN T H E ENERGY FIELD

a Miscanthus as a source of energy

Growing o f Miseanthus

Drying

Harvesting

30 t/ha biomass

D u n n g winter

Special machines 1o i ' be developed

in the fields

Transportation and storage

Buming Special local

.

_

_~wer~t~tjo,~

b MISCANTHUS: ENERGY SOURCE FOR TOMORROW?

P R O D U C T IO N SCENARIO (Germany)

PRICE SCENARIO (Germany)

• Miscanthus (envisioned for 2000)

• Miscanthus I I 0 - 210DM/I 140 - 266 DM/t OE*

• Available area 2 mill. ha • Yield 60 mill. t • Energy 25 mill. t OE*

• Heating oil 200 - 400 DM/t OE*

• Fossil energy sources • Total energy used 245 mill. t OE*

As already mentioned, the use of renewable resources in the energy field would be the only way to significantly save on fossil resources while simultaneously reducing agricultural production surpluses as a synergistic effect• World energy demand has increased by more than 40% over the past two decades (Fig. 4). Symptomatically, global oil demand reached a constant level after the first and second oil crises in 1973 and 1979. However, beginning in the early 1980s a significant and constant growth in fossil fuel use is detectable• As a matter of fact this is not the case for renewable resources• Renewable resources made no measurable contribution to world energy supply even in 1990. The analzsis of oil consumption in O E C D a~d n o n - O E C D countries will show in more detail the development in energy demand• Energy consumption in O E C D countries is regarded as being virtually constant, whereas in n o n - O E C D countries fossil resources consumption is rapidly increasing. For example, oil consumption in oil-producing countries and Southeast Asia is doubling. While figures show that industrial countries have reached a level of constant oil consumption, programs for the development of alternative energy sources, for example the use of renewable resources in the energy field, have been started. In the energy sector different possibilities for renewable resources are being discussed and examined; for example whole-plant combustion,

• Possible contribution of Mi~..anthus to German energy supplies 10%

* oa~ . ~

Fig. 5. a. Production of miscanthus, b• Figures for the use of Miseanthus as energy source. bioalcohol production and its use, especially as gasoline for cars, or rape-seed oil and its methyl ester as fuel for diesel cars. The two projects that are most discussed, widely published and funded with huge amounts of money are the 'Alternative Energy Projects'; the use of Miscanthus or elephant grass as energy sources in whole-plant combustion and the 'Biofuel Project' based on rape-seed oil or its methyl ester• The first is the subject of several different evaluations by public institutions or industry in different parts of G e r m a n y (Fig. 5). The basic ideas are: to use Miscanthus as a prototype of a perennial C4 plant with a very effective CO2 fixation mechanism; to grow this plant with a high biomass yield under optimal agricultural conditions. The yield of biomass is in the range of 30 t o n s / h a , compared to 6 t o n s / h a for wheat, for example• The biomass dries during winter in the fields and is harvested with special machines. The biomass is collected and used for combustion in local power stations• To obtain an idea of the profitability of Miscanthus a production and price scenario will be discussed. Given an acreage of about 11 million

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cations of renewable resources in the non-food sector which are broadly being discussed at the m o m e n t are: - in the energy field, for example as feedstock for power stations or alternative fuels; as a base for new materials in technical applications and polymers; - and last but not least as a second feedstock for chemical synthesis. In the following sections, developments and perspectives of renewable resources in these three areas will be discussed.

359

made by the German Federal Ministry of Energy, Agriculture and Forestry (BMELF). With a reimbursement of DM 2000 per hectare the costs for Miscanthus would be in the range of DM 110-210 per ton. This corresponds to DM 140-270 per ton of oil equivalent. These figures compare to DM 200-400 per ton of oil equivalent based on a price of $15 per barrel. According to these figures Miscanthus is competitive today. Provided that all technological barriers are surmounted, Miscanthus could make a contribution to future energy supplies.

a Production of rape-seed oil methyl ester

1.Pressing I

Rape

1Harcesti,i Rape-seed ~

I 0.92 ha

FTransRape-seed oil ~

2.75 t

1.1t

Rape-seed oil methyl ester t

[

It

+

13 Rape-seed oil methyl ester: Biofuel of the future?

PRODUCTION SCENARIO (Germany)

PRICE SCENARIO (Germany)

• Rape-seed oil methyl ester

(envisioned for 2000)

• Rape seed oil methyl ester 2.00 DM/1 • Fuel 0.44 DM/I

• Available area 2.0 mill. ha • Rape-seed oil methyl ester 2.2 mill. t

• Subsidization need for rape-seed oil methyl ester per 1:

• Fuel (1990) • Total amount • Farming

1.56 DM

22.0 mill. t 1.5 mill. t

• Possible contribution of rape-seed oil methyl ester to fuel supplies 10% Fig. 6. a. Production of rape-seed oil methyl ester, b. Figures for the use of rape-seed oil methyl ester as energy source.

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hectares in Germany, and taking the 5-year crop rotation system into account, about 2 million hectares would be available for Miscanthus in Germany. Assuming a yield of 30 t o n s / h a , a total amount of 60 million tons of biomass would be generated every year. This corresponds to about 25 million tons of oil equivalent. This rough estimation clearly shows, firstly, that Miscanthus will not replace oil as a source of energy, and secondly, that the contribution made by Miscanthus could be as significant as 10%. The price scenario is based on first estimations

360 subsidized by about DM 0.80-0.90/1 to make it competitive with soybean oil. Taking these subsidies into account, the price of the methyl ester is about DM 1.15/1. This is the price range for diesel fuel today. The scenario demonstrates that, although it might not be realistic to produce and subsidize large oil ester volumes, it could make sense for a few applications, for example in city centers or water-protection areas as well as forests, to use rape-seed oil esters to reduce environmental pollution.

3. R E N E W A B L E R E S O U R C E S CHEMICAL INDUSTRY

FOR

THE

The chemical industry's raw materials base has changed over the decades. At the beginning the sole raw materials employed were renewable resources and coal. At the end of last century the use of coal increased. In the 1930s oil was beginning to substitute coal as a feedstock. And it replaced to an even. greater extent coal and renewable resources. This process was stopped by the oil crises in the 1970s. At the beginning of the 1970s the German chemical industry used only 1 million tons of renewable resources. According to

b

Renewableresources a

Feedstock consumption by the chemical Industry in the Federal Republic of G e r m a n y (1985)

Change in the structure of the chemical industry's feedstock base

Volume in tons 13 mi,.

Feedstock base

•N•a•ie•&

o,

mill.

2.7 mill. / ~'~"

,,

,..:

I

/ I

1850

_~

"%.

"v'v'~'r~ .~.44 ~

/

coal

renewable resources

%#

Z'...... .... . . . J I ....

1950

_,,q

"T

I

1980

2000

Year

Value in % 65

1.8 mill. 10%

5

approx

,

petroleum



natural gas



renewable resources

coan

Fig. 7. a. Structural changes in the chemical industry's feedstock, b. Feedstock consumption by the German industry.

22

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The second project, 'Rape-seed oil methyl ester' (Fig. 6), aims at the use of plant oil as a fuel substitute. Rape - in addition to sunflowers - is today the only oil plant suitable for growth and good yields in north-west Europe. The process for the use of rape-seed oil comprises the following steps: harvesting, pressing, and extraction. After extraction rape-seed oil is converted to the corresponding methyl ester by methanolysis. The esters are useful diesel substitutes. As the flow diagram (Fig. 6a) indicates, the methyl ester yield is, at about 1 t o n / h a , relatively low compared with the 30 tons of biomass yielded by Miscanthus. Furthermore, by-products such as 1.6 tons of rape-seed meal and 100 kg of glycerol should be taken into account. The production and price scenario shows the potential of these methyl esters. About 2 million hectares of rape yield 2.2 million tons of ester. This volume could replace about 10% of the total amount of diesel fuel consumed in Germany. The price of rape-seed oil ester is estimated at about DM 2.-/I. This means that subsidies of about DM 1.56/1 are needed to make rape-seed oil methyl ester competitive to diesel fuel at DM 0.44/1. The bare figures do not give a fair description. Generally, rape-seed oil in Europe is

361

Uses of renewable resources

Oils and fats

Detergent base materials and detergents Raw materials for surface coatings Textile, paper and leather auxiliaries

Starch

Auxiliary in paper manufacture

Market prices of selected raw materials and chemicals

._



~=

• citric acid • ethylene oxide

• propytene

• acetic acid • ammonia

lactic a c i d

oxide

• acrylic acid

• ethylene

• ptopylene *methanol • benzene

• ethanol

• starch • melasses ~cmde * oil ! i i 0

• sugar

• tallow • sunflower oil i 500

* c a s t o r oil i

i

1000

1500

2000

i

I 2500

> Dlvl~on

Fig. 9. M a r k e t prices of s e l e c t e d raw m a t e r i a l s a n d c h e m i c a l s b a s e d on p e t r o c h e m i c a l s or r e n e w a b l e resources.

Two important prerequisites for the increasing use of renewable resources are a competitive price and the availability of conversion technologies. Figure 9 shows raw materials and chemical products based both on petrochemicals and on renewable resources of different upgrading levels as a function of the price. If we compare world market prices for raw materials, it is amazing that renewable resources and their derivatives are in a similar range to base products derived from petrochemicals. Therefore, based on world market prices, renewable resources are a force to be reckoned with. This is especially true and important in fields where we can make use of nature's synthetic potential. For example sugars with their high oxygen content might be interesting building blocks for alcohols, polyols and other oxygen-containing compounds. The linear structure of oils and fats may give opportunities in surfactants and polymers. However, in all these calculations we should not forget the amount of integration involved - from raw materials to the use of all by-products.

Carbon source for biotechnological processes

Packaging materials

4. Cellulose

Sugar

Fibers FiLlers

Carbon source for biotechnological processes Building block for vitamins Polyurethanes

Fig. 8. R e n e w a b l e r e s o u r c e s and t h e i r fields of application.

RENEWABLE

RESOURCES

IN

THE

MATERIALS SECTOR Use of renewable resources in the materials sector: - Fibers - Packaging materials - Polyurethanes

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new figures this amount has doubled within the last few years (Fig. 7). In G e r m a n y about 20 million tons of feedstocks are used in the chemical industry, made up as follows: about 13 million tons of oil, about 1.5 million tons of natural gas, about 3 million tons of coal and nearly 2 million tons of renewable resources. Renewable resources thus account for about 10% of total feedstocks, but represent about 20% of their value. Renewable resources used in the chemical industry are oil and fats, starch, pulp and sugar (Fig. 8). Oils and fats are used for the production of detergents, as raw materials for surface coatings, and textile, p a p e r and leather auxiliaries. For the use of oil and fats standard reactions such as saponification, hydrogenation and esterification have been established. Starch is an auxiliary in p a p e r manufacture, a carbon source for biotechnological processes, and is used in packaging materials. Cellulose is employed in the textile industry and other applications such as filters, explosives, celluloid, etc. The use of cellulose has decreased over the last few years. Sugar is used as a feedstock for biotechnological processes, as a building block for vitamins and for polyurethanes. The use of renewable resources will increase in the next few years because numerous research programs have been started at universities and in R & D in industry.

362 re-

This area is rather heterogeneous as it consists of natural fibers such as cotton for textile use. Cellulose and derivatives are traditional raw materials for p a p e r and packaging or starch as builder in p a p e r and detergents. Polyurethanes as plastics are used for numerous technical applications. In the last few years several new products exhibiting biodegradability have been developed. Examples are combinations of starch with other polymers, cellulose diacetate, polyhydroxybutyrate, and polylactides. Some of these developments are on the threshold of commercialization.

Because this symposium deals with this topic 1 would like in this review to concentrate on one special field that is closely related to chemistry: the use of renewable resources in the production of polyurethane. All the processes for the production of polyurethane follow basically the same route (Fig. 10). A polyol is reacted in a polymerization step with a diisoeyanate c o m p o n e n t to yield a polyurethane. On this principle 4.6 million tons a year of polyurethane are produced worldwide for different purposes. As one can imagine, the favorite polyols are glycerol, sucrose, sorbitol or starch. They are cheap starting materials with the right set of functional groups. Polyurethanes partly made from renewable resources are used for bumpers for cars. The amount of renewable resources consumed is estimated at 100000 tons per year.

5. R E N E W A B L E DUCTION

Use of renewable resources in the materials sector Polvurethanes as an e x a m o l e

HO . . . .

OH

+

O=C=N . . . .

polyol

.....

N=C=O

diisocyanate

o-

C-N

......

a

N-C-ta_J n

polyurethane

Polyol:

glycerol saccharose sorbitol starch

Fig. I0. Production of polyurethanes based on renewable resources.

RESOURCES

IN THE

PRO-

OF C H E M I C A L S

Two strategies can be differentiated for the use of renewable resources for the production of chemicals. The first strategy is the use of renewable resources for established product lines (Fig. lla). New technologies have to be developed by which renewable resources can be converted for example into chemical intermediates. The advantage of this strategy is that it would follow established product lines in the chemical industry. This might also enable high-volume products to be synthesized from renewable resources. The second strategy is to use nature's synthetic potential for the development of new products with new properties. Both strategies have already been used successfully. Some selected examples of both strategies will be discussed below. Propanediol is a chemical intermediate for numerous applications such as polymers. It is produced worldwide in the range of about 2 million tons per year. The established industrial synthesis starts from propene. In a series of conversions propene is oxidized to propanediol. A new route to propanediol is the selective hydrogenation of

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Packaging materials based on renewable sources: - Starch/polyethylene - Thermoplastically processable starch - Starch/additives - Starch graft polymers - Cellulose diacetate - Polyhydroxybutyrate - Polylactides

363 b

Intermediates based on renewable resources

a

Strategies for the utilization of renewable resources in the chemical industry

PrgpanedioI as an example •

Petrochemical-based production OH

Development of technologies for the manufacture of established intermediates

OH

on the basis of renewable resources



Alternative route from renewable resources CHzOH rio _ ' ~,~~ ° \ HO "~""'~ V ' ' ~ - OH oH

Development of new products having new properties

OH pressure,temperature catalyst,H,

IOH

Fig. 11. a. Strategies for the use of renewable resources in the chemical industry, b. Propanediol based on renewable resources.

sugars in the presence of a catalyst under high pressure and at elevated temperature (Fig. l lb). This process yields propanediol in a single step, but ethylene glycol, hexanetetrol and water are

produced as by-products. The yield of the different products is influenced by the reaction conditions, especially temperature. The selling price for propanediol is in the range of DM 2300/ton.

a Fine chemicals based on renewable resources Vitamin B 2

Vegetable oil

Fermentation i

b Surfactants based on renewable resources

Separation

L Drying

Examole •

o HN

Alkylpolyglucosides by reaction of glucosides and alcohols

.o

CH2-(CHOH)3-CH2OH Vitamin B 2

o

o-~

o

a

~

"

N



Objective Fully degradable nonionic surfactants

Fig. 12. a. Microbial synthesis of Vitamin B 2 based on renewable resources, b. APGs, surfactants based on renewable resources.

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j..

Naphtha

364

solvents. Here, linseed oil - due to its linoleic acid content - is much in favor. Worldwide a few hundred thousand tons of linseed oil are used in non-food materials. Other products made from renewable resources are for example crop protection agents, emulsifiers, cosmetics, aromas and natural dyes. To increase the use of renewable resources there will have to be intensive cooperation between basic research, plant breeders, producers, processors, industry and polities. For example, we need to know more about chemical reactions with renewable materials. The range of methods for utilization as materials will have to be improved. Plant breeding is essential to improve the crop yield and the amount of desired constituents. In this field the progress of biotechnology and genetic engineering is important. Worldwide production is necessary to ensure reliable supplies with constant quality. Last but not least one of the most important factors is competitive prices for these renewable resources. The potential of renewable resources for nonfood materials can be summed up as follows. Renewable resources are a second feedstock; they improve flexibility in feedstock selection and they provide additional potential for innovation for new products and processes. However, it should not be forgotten that in the foreseeable future fossil resources cannot be completely replaced by renewable resources.

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Depending on the sugar price and the reaction selectivity there may be a chance for this process to be competitive in the future. Industrial applications for the hydrogenation of sugars already exist, for example the hydrogenation of glucose to sorbitol. Sorbitol is an intermediate for the production of vitamins and numerous other applications. Another possibility for renewable resources is as a carbon source for fermentation processes. Biotechnological processes are increasing in importance for the synthesis of chemicals. One example is vitamin B 2 (Fig. 12a). Vitamin B 2 is used in the feed, food and pharmaceuticals sectors. It can be produced - despite its complicated structure - in a single step starting from vegetable oils by a biotechnological process. The classical production sequence is a 5-step synthesis. An example of the second strategy is the synthesis of detergents of the alkyl polyglucoside type (Fig. 12b). These products are synthesized from sugar and a fatty alcohol. Alkyl polyglucosides are fully degradable nonionic surfactants. Worldwide capacity is at present in the range of 30000 tons per year. It is expected that alkyl polyglucoside will replace petrochemical-based surfactants. There are numerous other applications for renewable resources which can only be mentioned here. Paints and surface coatings use plant oils as

365

on

LACTIC ACID BACTERIA Genetics, Metabolism and Applications To be held in Noordwijkerhout, The Netherlands, on 5-9 Sept. 1993

Sponsors: Netherlands Society for Microbiology and the Federation of European Microbiological Societies (FEMS).

Information and Pre-registration: Please contact: International Agricultural Centre, P.O. Box 88, 6700 AB Wageningen, The Netherlands. Tel: +31-8370-90111 / Fax: +31-8370-18552

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Fourth Symposium

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FEMS Microbiology Reviews 103 (1992) 355-364 © 1992 Federation of European Microbiological Societies 0168-6445/92/$15.00 Published by Elsevier 355 F...

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