1.2.1 The Nature of Fossil Raw Materials

The current global economy is very much based on fossil resources to produce energy (electricity, fuel, heat) and organic chemicals. The initial source of these feedstock has been biomass transformed through geological processes into crude oil, natural gas, black coal as well as lignite and peat. What makes these materials valuable for use in energy and chemistry processes is their high energy as well as carbon content (Table 1.1). The most valuable fossil resources are the hydrocarbons that consist only of carbon and hydrogen. Subgroups are, for example, alkanes (saturated hydrocarbons; C_nH_2n+2), cycloalkanes (C_nH_2n), alkenes (unsaturated hydrocarbons; C_nH_2n), and aromatics (ring-shaped molecules) differing in the number of carbon and hydrogen and molecular structure.

Coal, especially black coal, is the oldest fossil resource. Formed from terrestrial plant biomass, it has been consolidated between other rock strata and altered to form coal seams by the combined impact of pressure and heat under low-oxygen conditions over about 300 million years. Black coal is extracted by open-cast mining as well as deep mining (up to a depth of 1500 m). It is composed primarily of carbon.

Fossil oil has been formed over a time period of about 100 million years by the exposure to similar conditions on sedimentation layers of marine organisms such as algae and plankton. Under such conditions, the long-chain organic molecules of the vegetable biomass are split into short-chain compounds forming liquid oil. It accumulates in specific geological formations called crude oil reservoirs.

Some fractions even split down to molecules with only one carbon and become gaseous methane (CH₄). Therefore, oil deposits (and coal mines) always contain methane of more or less similar age. Methane sources covered by nonpermeable geological layers lead to real methane deposits. From such geological formations, the gas can be extracted in the form of natural gas. Natural gas can also be the result of biological catabolic processes degrading biomass. These deposits are also found under nonpermeable geological formations but have been formed over a period of about 20 million years.

As oil and gas generation needs high-pressure conditions the corresponding deposits are highly pressurized. If such sites are drilled, oil and gas escape through the well – a process called primary recovery allowing to exploit 5–10% of the total oil and gas. By pumping (secondary recovery) and more sophisticated methods (tertiary recovery) more oil and gas can be extracted. Obviously exploiting an oil and gas deposit is easy in the beginning but becomes more and more technically complex and costly with time.

Lignite has a similar origin as black coal. It has been exposed to the harsh geological conditions for up to 65 million years and can be extracted by open-cast mining. The carbon content is lower than that in black coal, but extraction costs are in average more beneficial.

Peat is another fossil resource. It is as well formed from terrestrial plants under aplent moor conditions when the biomass decays for several 1000 years under low-oxygen conditions. Peat contains the lowest carbon and highest water share under fossil resources. It is recovered from ground.

All fossil resources have the following common characteristics: (i) they are rich in carbon and energy; (ii) their composition is not very complex and quite homogeneous; (iii) they can be produced at moderate, though growing cost; and (iv) fossil resources can be shipped easily by railway, tankers, and pipelines.

1.2.2 Industrial Use

1.2.2.2 Chemicals

The cheap and seemingly unlimited availability of fossil resources not only triggered an energy-hungry industrialization but also the innovation leap into today's chemical industry. High carbon content in combination with easy logistics through pipelines and tankers made especially oil and gas an ideal industrial feedstock. Seven percent of the global oil and about 2% of world natural gas consumption go into chemicals demonstrating that fossil oil still dominates the global chemical industry (70–80% of chemicals are derived from oil, 8–10% from gas, 10–13% from biomass, and only 1–2% from coal; compare Table 1.3)

Naphtha	Natural gas	Coal	Bio-based feedstock
71	14	2	13

Since ancient times chemicals and biochemicals had been produced from natural reservoirs or from biological resources, respectively. For example, sodium carbonate was imported by Europe from soda lakes in Egypt and Turkey or extracted from water plants. The alkaline solution of soda ash (sodium carbonate) is in fact named after Arabic “al kalja” for the ashes of water plants. In 1771, an alternative method changed the world when Nicolas Leblanc (1742–1806) in France invented the chemical synthesis of sodium carbonate by using coal as the carbon source. This real innovation is today acknowledged as the starting point of chemical industries.

Structural Materials

Since the mid-nineteenth century natural product chemistry tried to use biomaterials as a feedstock to organic chemicals. For example, cellulose, the most abundant plant polysaccharide, has been investigated intensively. The fact that in 1846 three German chemists simultaneously but independently invented a method to produce nitrocellulose from cellulose demonstrates how the time was right for such an innovation. It marked the change from biomaterials to bio-based materials. Though highly inflammable, nitrocellulose entered the market with great success because it was able to replace expensive materials such as whale baleens especially used in ladies costumes as well as silk. Later in 1910 viscose was developed from cellulose in Germany as a fiber material that is still in use. Another example of the efforts to gain independence from natural starting materials by developing synthetic materials is the invention of galalith plastic from casein in 1897 again by German chemists. Obviously, there was a market waiting for more materials from modified biological sources, and there were scientists exploring chemistry.

Dyes

Whereas the examples mentioned so far represent more structural materials for fibers and tissues, instruments, and housing, the next group demonstrates the boosting power of added-value chemicals. Color design mostly does not directly determine the utility of a product, but it adds value and makes a difference. Since ancient times dyestuffs were produced at considerable expense from plants, animals, and minerals. At the end of the nineteenth century, chemistry paved the way to cheap dyestuffs and a world full of colors for the first time, thus ending the industrial era of dye plants. The synthesis of the red dye Alizarin in 1869 by German chemists Carl Graebe (1841–1927) and Carl Liebermann (1842–1914) replaced the natural dye made from dyer's madder (Rubia tinctorum) within a short time period. Alizarin became one of the first products of BASF, founded in 1865 in Mannheim, Germany, by Friedrich Engelhorn (1821–1902). Another red dye, fuchsin, first synthesized in 1858 became the starting point for Hoechst AG, founded by Carl Friedrich Wilhelm Meister (1827–1895), Eugen Lucius (1834–1903), and Ludwig August Müller (1846–1895) in Hoechst close to Frankfurt and only 80 km (50 miles) from Mannheim. In 1878 followed Indigo, another synthetic dye, which was developed by Adolf von Baeyer (1835–1917). Indigo gained industrial relevance at BASF and Hoechst when Johannes Pfleger (1867–1957), chemist at Degussa AG in Frankfurt/Main, improved the process economics significantly. Until the early twentieth century, dye products were dominating commercial chemistry and even the whole industry was called dye chemistry.

Receptive markets and growing chemical science were now joined by entrepreneurs. It is important to understand the significance of these three factors working together. But in the end, industry is made by competent individuals who complement each other, build friendship, realize the business option, and take the chance. The men mentioned here – many friends since university studies – formed such a network that became the starting point of the German chemical industry.

Drugs

As of today successful companies use scientific and technical competence to broaden their product portfolio, develop new application fields, and enter profitable markets. In the early twentieth century, the potential of synthetic drugs had been realized and especially the German dye industry started to invest in research and development. Arsphenamine (Salvarsan®), a syphilis drug, developed by the German physician Paul Ehrlich (1854–1915) and the Japanese bacteriologist Sahachiro Hata (1873–1931) in 1910 became a cash cow to Hoechst AG. In 1935 followed Prontosil®, the first sulfonamide developed by Fritz Mietzsch (1896–1958) and Josef Klarer (1898–1953) at Bayer AG in Wuppertal. Noticeably, this chemical group is also used as azodyes demonstrating how competence in a specific field can lead to a spillover invention in a very different application. Gerhard Domagk (1895–1964) discovered the antibacterial effect and received the Nobel Prize in 1939. These examples not only demonstrate how gaining experience in synthetic chemistry in one field (materials, dyes) led to exploring very different markets (pharmaceuticals) but also how chemical industries early integrated microbiological competence.

The pharmaceutical business opened the door for biotechnology in chemical industries when the Scottish bacteriologist Alexander Fleming (1881–1955) explored antibiotics in 1928. He realized that the fungi Penicillium secretes the antibiotic penicillin, a discovery that was honored with the Nobel Prize in 1945. Since 1942 in England Glaxo (pharma company; founded in 1873 and originally in the baby food business) and ICI (chemical industry, founded in 1926) but especially in the US Merck & Co (1917; separated from Merck KGaA, a German pharma company founded in 1668) and Pfizer & Co (founded in 1849; biological pesticides) developed fermentative production processes based on the cultivation of Penicillium chrysogenum. Companies with very different backgrounds in chemistry, synthetic drugs, and food production got involved in developing early fermentation methods. It should be emphasized that those companies focused on fermentation because there was no technical alternative. Penicillin antibiotics were not available by chemical synthesis. The production of penicillin is therefore seen as the starting point of industrial biotechnology (in contrast to traditional food biotechnology using microbial processes such as yogurt, beer, and wine fermentation).

Drugs added a quite different quality to the chemical industry's product portfolio. This chemical product sector is characterized by extremely high functionality to fight diseases, thus adding real value and commercial profit. In addition, this sector is extremely knowledge based – documented by Nobel Prize–winning research.

Polymers

A combination of extensive science and the availability of carbon sources triggered in the 1930s another chemical success story: polymers. Increasing capacities in oil refineries not only provided gasoline and diesel but with naphtha (Table 1.4) also the fraction of long-chain hydrocarbons to be cracked down to methane, ethylene, and propylene. Platform intermediates like these are till today the biggest chemicals by production volume. Their carbon content is the share of carbon of the molecule's molecular mass (g mol⁻¹). Ethylene, for example, consists of two carbon (atomic mass 12 u) and four hydrogen atoms (atomic mass 1 u), which gives a molecular mass of 28 g mol⁻¹ and a share of carbon of 85.7% (Table 1.5).

25 °C	>	>	>	>	>	350 °C
Refinery gas	Gasoline	Naphtha	Kerosene	Diesel oil	Fuel oil	Residue
Bottled gas	Automotive fuel	Chemical feedstock	Aircraft fuel	Truck fuel, bus fuel	Ship fuel, power generation	Bitumen for road construction

Chemical category	Chemical		C (%)	Production (million tons)	C content (million tons)
Olefins	Ethylene	C2H4	85.7	123	105
	Propylene	C3H6	85.7	75	64
	Butadiene	C4H6	88.9	10	9
	Hexane	C6H14	83.7	5	4
Aromatics	Xylenes	C8H10	90.6	43	39
	Benzene	C6H6	92.3	40	37
	Toluene	C7H6	91.3	20	18

Not only the availability of a cheap and easy-to-handle feedstock pushed chemical industries but also the often highly advantageous stoichiometric product yield. For example, ethylene (MW 28.05 g mol⁻¹) and propylene (42.08 g mol⁻¹) are available from hexane (86.18 g mol⁻¹) with a yield of 98% kg kg⁻¹.

Already in 1912 the Chemische Fabrik Griesheim-Elektron (later a production site of Hoechst AG) close to Frankfurt (Germany) tried to find new applications for ethylene, which was produced by oil refineries in big amounts. Finally, the chemist Fritz Klatte (1880–1934) synthesized vinyl chloride from acetylene (C₂H₂; synthesized by dehydrating ethylene) and hydrogen chloride. From 1928 (several companies in the United States; 1930 BASF in Germany) started production and polymerization to polyvinylchloride (PVC) on large scale. PVC became the first synthetic material not starting from any natural building block and a real milestone in chemical innovation, which had been induced by the availability of a new feedstock. Nylon, patented in 1935 by the chemist Wallace Hume Carothers (1896–1937) at E. I. du Pont de Nemours in Wilmington (Delaware, USA), turned out to be the next big step in polymer innovation. The theoretical base of polymer chemistry had been laid at the University of Freiburg (Germany) by Hermann Staudinger (1881–1965) who received the Nobel Prize in Chemistry in 1953. Today, polymers represent the biggest chemical product group in a volume of 241 million tons in 2012 (Statista, [2013]). China leads with a market share of 23.9%, followed by Europe (20.4%) and the NAFTA region (19.9%).

With polymers the chemical industry finally left also in the field of bulk chemicals the level of craftsmanship, which had characterized this industry in the beginning. From then on science and fast advance in knowledge (documented in patents) became a primary competitive driver (Table 1.6).

	1900	1920	1940	1960	1980
Pharmaceuticals	Salvarsan® Aspirin®		Antibiotics	Birth-control pill	Anti-AIDS protease-inhibitor
Paints and coatings		Acryl lacquer			Water-based lacquer
Adhesives	Phenolic resin			UV-crosslinked adhesives	Solvent-free adhesives
Surfactants				Biologically degradable tensides	Phosphate-free tenside
Polymers	Synthetic rubber Viscose	Nylon	Teflon Styropore		Microfibers
Agrochemicals	Haber–Bosch process				Linking herbicide and plant breeding
Energy			Solar cell

1.2.3 Expectancy of Resources

Common sense suggests that fossil resources are limited and will be consumed eventually. From a physical point of view, such a statement sounds simple and is absolutely right. Economically, it is more complex because geological resources differ in cost of exploitation (Table 1.7).

Geological deposits too costly to be explored today may become competitive tomorrow. An example is today's shale gas boom especially in the United States and the earlier oil sand exploitation in Canada. Both deposits remained untouched and were not included in oil statistics for decades but reached competitiveness because the rising oil price allowed more expensive oil production methods. Therefore, we need to differentiate between reserves and resources. Resources define the total volume of fossil feedstock deposited underground, whereas reserves give an idea of what is exploitable today with the state-of-the-art profitable methods. Economists therefore calculate the “static lifetime,” which is the time range within which a given feedstock will be available under current economical conditions with current technical means under consideration or the current consumption.

The total resources in fossil oil are estimated to amount to 752 billion tons. Out of this volume, 383 billion tons is known as exploitable with today's technical means at feasible coast; 167 billion tons or 44% has already been delivered since the beginning of industrial oil production. About 4 billion tons is produced annually. Nonetheless, oil resources are of course limited but are not to be expected to run out within a short term. The very same is true for gas and coal (Table 1.8). Static lifetime expectancy is an important issue because as long as fossil feedstock is on the market it will be the competitive benchmark for bio-based raw materials.

1.2.4 Green House Gas (GHG) Emission

Nevertheless, in view of the climate change, we need to ask whether it is wise to use fossil resources completely. Undoubtedly, producing energy from oil, gas, and coal by burning leads to CO₂ (molecular mass 44 g mol⁻¹), which is emitted into the atmosphere; 27.3% of it is carbon (Table 1.9).

As atmospheric CO₂ reduces global infrared emission into space the consumption of fossil resources has a warming effect on the atmosphere, which is broadly agreed to contribute to man-made (anthropogenic) climate change. Due to the already occurred emission an increase in global temperature by 1.3 °C seems unavoidable in the long run of which 0.8 °C increase is already proven (because of the climate system's inertia it is a slow process). However, to limit global warming to 2 °C CO₂ emission should not exceed a cumulative volume of 750,000 million tons till 2050 (Wicke, Schellnhuber, and Klingefeld, 2012). This is equivalent to only 21 years of current emission activity of 34,500 million tons. Already the common people are affected by the climate change by sea-level rise in Bangladesh, desertification in Spain, and drought in the United States. Climate change is one of the most pressing current issues forcing governments and industries to reduce the consumption of fossil resources.

1.2.5 Regional Pillars of Competitiveness

When looking on the global map of fossil resources, it is interesting to note that the sites of deposits and production (Middle East, North America, Russia) are mostly not identical with the sites of processing (Figure 1.1). For example, Belgium, Germany, and Netherlands are among the five biggest global chemical regions. Because this region depends on importing oil, it is called after its harbors and rivers which, however, not only serve as the logistics backbone but also as production sites: ARRR (Antwerp, Rotterdam, Rhine, Ruhr).

Although it must be considered that the starting point of industrial activities in this region has been the availability of coal and a little fossil oil the ongoing success of its industries does not depend on feedstock directly on site. More relevant is an efficient regional logistics system for high-volume feedstock imports and processed goods exports through railroad, pipeline, and river and sea transport. Other equally relevant pillars of competitiveness are academic research and education facilities, skilled workforce, effective governmental and public administrative institutions, and last but not least public acceptance.

How the integration of these factors leads to the innovation leap of successful industries producing marketable goods, creating jobs, and inducing a real innovation cycle with a continuous product pipeline is demonstrated by the history of chemical industries. In the nineteenth century, Germany's universities trained excellent chemists who often kept lifelong friendship and formed an effective business network. They used the new raw material of mineral oil, which was easily available along the river Rhine to develop products for receptive markets like dyestuff and more. With academic excellence, entrepreneurs and investors started production facilities for a society honoring innovation. Nobel Prize and global players in chemical industries were the result. Similar chemical clusters evolved in the United States and Japan (ranking today number 1 and 2). China surpassed Germany a few years ago; its industry grew in the beginning due to beneficial cost but has increasingly gained relevance also because of top-ranking science. Germany's chemical industry still ranks number 4 (Table 1.10). When looking at global regions, the Asian chemical industry is today leading (Table 1.11) especially due to China.

1.2.6 Questions for Further Consideration

• What makes fossil feedstock a valuable industrial feedstock?
• What are the most important applications of fossil feedstock? What is their share in fossil feedstock use?
• What are key success factors of leading fossil-based chemical production sites?
• Should fossil feedstock be used till running out? Why not?

1.3.1 Oil Crops

Oil crops deliver vegetable oil consisting in principle of saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids. Oil crops deposit fatty acids in the seed from which it is extracted. The remaining meal is often rich in protein and used as feed additive.

Soybean (Glycine max) delivers oil and protein. The oil content of the seed varies between 14% and 24% and is used for food (cooking oil, salad oil, margarine) and industrial applications whereas protein goes into feed. Linoleic acid (C₁₈H₃₂O₂; 49–47% of fatty acids), oleic acid (C₁₈H₃₄O₂; 18–25%), and linolenic acid (C₁₈H₃₀O₂; 6–11%) are the most relevant fatty acids. The spectrum of fatty acids is the subject of breeding efforts, as especially linolenic acid causes problems concerning oxidation and undesired flavor. After extracting oil from the soybean the bean meal is left. It is rich in protein (42–47%) and therefore a valuable feed additive. Soybean is cultivated worldwide with highest acreage in the United States and Brazil.

Rapeseed (Brassica napus) delivers oil (40–50%) and protein (20–25%). Wild-type (meaning the wild variety) rapeseed contains erucic acid (C₂₂H₄₂O₂) with a share of 25–50% among the fatty acids and some glucosinolate (glucoside containing sulfur and nitrogen; a plant defense active against pests). Both compounds have a negative nutritional effect, thus preventing the use of wild-type rapeseed in food and feed applications. Plant breeding reduced the content of both compounds and today's cultivars produce 52–66% oleic acid, 17–25% linoleic acid, and 8–11% linolenic acid. Rapeseed meal contains 33% protein and is a valuable feed component. Rapeseed is cultivated especially in Europe.

Sunflower (Helianthus annuus) is an annual crop producing seeds with an oil content of 50%. The main fatty acid components are linoleic acid (55–73%) and oleic acid (14–34%). Extracted meal contains 40–45% and is used both in food and feed applications. Sunflower is especially grown in Russia and Ukraine.

Oil palm (Elaeis guineensis) is a palm tree cultivated in plantations. It produces up to 15 years (first time 3 years after planting). Fatty acids accumulate in the fruit pulp as well as in the seed kernel making up 45–50% of the fruit. The pulp fatty acids consist of palmitic acid (44%; C₁₆H₃₂O₂), oleic acid (39%) linoleic acid (11%), and some minor fatty acids. Palm kernel is especially rich in saturated fatty acids, mainly lauric acid (48%; C₁₂H₂₄O₂) and stearic acid (16%; C₁₈H₃₆O₂). Malaysia and Indonesia are leading producers of palm oil.

Jatropha (Jatropha) grows as plant, shrub, and tree. Trees that are cultivated for producing vegetable oil grow even on poor soil. Fatty acids are deposited in the seed to up to 30% consisting of 30–52% linoleic acid, 30–44% oleic acid, 15–17% palmitinic acid, and 6–8% stearic acid. Because seeds contain toxic compounds Jatropha has not been domesticated so far and yields are variable. The oil is highly suitable for fuel applications and therefore Jatropha gains increasing industrial interest. Currently, Jatropha oil is especially produced in India, Indonesia, and China. Table 1.13 lists the global consumption of major vegetable oils.

1.3.2 Sugar Crops

Sugarcane (Saccharum officinarum) is a multiannual grass, which deposits sucrose (70–88%), glucose (2–4%), and fructose (2–4%) in its stalks. Stalks contain 73–76% water and 24–27% solid materials of which 10–16% are soluble. This soluble fraction contains the sugar. It is extracted by repeated chopping, shredding, and washing the stalks. Processed stalks (bagasse) consist of 40–60% cellulose, 20–30% hemicellulose, and 20% lignin. Today bagasse is burned to produce heat and power for the sugar mill. Sugarcane can be harvested up to 10 times before replanting. Up to 10 tons sugar per hectare is produced. Sugarcane is especially grown in Brazil and India (Table 1.14).

Sugar beet (Beta vulgaris) is a biennial beet, which accumulates about 20% sucrose in its root. Water content of the beet is about 75–78%. Nine tons of sugar is produced per hectare of sugar beet. Beet leaves can be used as feed. It is cultivated in Europe and Russia.

1.3.3 Starch Crops

Corn (Zea mays) is an annual grass that forms male terminal tassels and female cobs. The cobs develop 8–18 rows with 25–50 maize grains in each row. Grains accumulate starch in up to 62% of fresh matter. The rest consists of 10% protein, 5% fat, and 5% fiber, vitamins, minerals, sugar, and water. Corn grains are at first used as starch source. Corn grain yield reaches 10 tons per hectare. If used as feed special varieties are harvested as whole plant biomass with a yield of up to 50 tons fresh biomass per hectare (15–20 tons per hectare dry mass). The biggest corn grower is the United States providing about 32% of global harvest (Table 1.15).

Potatoes (Solanum tuberosum) grow perennially and accumulate starch in tubers. The fresh matter content is about 15% starch (79% amylopectin, a highly branched polymer of glucose; 21% amylose, a helical polymer made of α-d-glucose). Top yields in Germany reach 6 tons of starch per hectare. Potato was at first grown for food, but later for industrial purposes as well. After starch processing, the remaining potato pulp contains hemicellulose, cellulose, protein, and pectin. It is used in enzyme production, fungi cultivation, and as fertilizer and feed additive. A special variety depositing only amylopectin for industrial markets has been bred recently by traditional breeding. A similar variety developed by genetic engineering did not enter the European market because of lack of public acceptance. Potato is grown in Europe, Russia, and China (Table 1.16).

Wheat, barley, and rye (Gramineae family) are grasses depositing starch (28% amylose, 72% amylopectin) in the grain. Starch makes 58% of the grain (fresh matter content) with 15% water plus cellulose, hemicellulose, and lignin of the seed hull. Up to 4 tons of starch per hectare is produced with wheat. Seed hull and straw are the most important by-products of cereal processing. Wheat is the most important crop and grown worldwide. Barley (Hordeum vulgare) and rye (Secale cereale) are especially grown in Europe and Russia, whereas sorghum (Sorghum) is cultivated in the United States, Africa, and Asia. Triticale (hybrid of wheat and rye) is grown similar to rye (Table 1.17).

Starch crops give an overview of the different characteristics of plants and the wide range of applications. Fresh potatoes come with about 85% of moisture but with more than 80% of starch, about 10% protein, and 5% fiber in dry matter. In contrast, corn kernels are relatively dry (15% moisture) come with a little less starch in dry matter (80%) but contain more protein and lipids. Lack of moisture and the high protein and lipid content make corn a more competitive industrial feedstock. About 80% of global starch production is corn based. The product portfolio available from corn is shown in Table 1.18.

HFCS, high-fructose corn syrup.

1.3.4 Lignocellulosic Plants

Miscanthus (Miscanthus) is a grass related to sugarcane and millet. It reaches up to 4 m in height and dry mass yield of 15–20 tons, even up to 30 tons per hectare. It is harvested like grass for the first time after 3 years and can be cultivated for at least 20 years. The biomass consists primarily of lignocellulose. Miscanthus is grown in Canada yielding up to 44 tons dry mass per hectare. Today, it is utilized thermally but the future potential is seen in second-generation energy carriers and chemicals. It can be cultivated on grassland (globally 3.55 billion hectare (Raschka and Carus, [2012]))

Woody biomass from short-rotation trees like poplar yields 10–15 tons per hectare annually within 4–6 years. The trees sprout after harvest again over a period of at least 20–30 years and are harvested every 2 years. Lignocellulosic biomass consists of 42–49% cellulose, 24–30% hemicellulose, and 25–30% lignin. It is today used for generating heat by burning. The material is quite identical with forestry waste (hardwood contains 42–51% cellulose, 27–40% hemicellulose, 24–28% lignin) or oil palm residues which is also basically lignocellulose. Its future potential is in second-generation energy carriers and chemicals. Under European conditions, forests add 12.1 m³ wood per hectare per year with an average density of 470 (pine) to 690 kg m⁻³ (oak). Global forest area is about 4 billion hectare with 264 million hectare planted (Adams, [2012]).

1.3.5 Lignocellulosic Biomass

Straw from cereals represent another lignocellulosic biomass. Today, it is used for livestock bedding and more low-value applications. As it is a by-product of cereal agriculture, thus part of an existing harvesting process, it draws special attention as a future second-generation carbon source. With an average cereal/corn relation of 1 to 1 100 million tons of cereal comes with about 100 million tons of straw. As 20–30% of the straw should be left on the ground for rotting and keeping the soil fertile about 70–80 million tons could be available from 100 million tons of cereal biomass for industrial use.

1.3.6 Algae

Microalgae consist of a single or only a few cells and produce fatty acids, carbohydrates, and some special ingredients by photosynthesis. Algae are cultivated commercially only for special compounds like astaxanthin, which is added to fish and poultry feed giving salmon and egg yolk its typical color. As biodiesel gets growing commercial attention, algae are evaluated as a source of lipids (up to 70% lipids of fresh algae biomass). Microalgae are seen superior to land plants due to high rate of growth, high yield per hectare, high energy content (Table 1.19), lack of lignin, and low cellulose content. They are cultivated in open ponds or specific photoreactors. In both the methods, algae are grown under light and supplied with atmospheric CO₂ or CO₂ emitted by an industrial plant. Therefore, such production systems neither occupy fertile land nor compete with food production. However, handling the large volume of water related with algae cultivation (pumping, product isolation) is costly and a significant hurdle in commercialization.

1.3.7 Plant Breeding

Plant performance characteristics and plant compounds are subject to optimization by plant breeding. If features like fruit and biomass yield (ton ha⁻¹ year⁻¹) or seed and biomass composition (e.g., starch, lipid, or lignin content) are targeted, genes in so-called output traits are addressed. These are the metabolic pathways controlling growth, biomass composition, and yield. Other breeding programs aim on cultivation parameters like germination rate and resistance against microbial pathogens and insects or draught. These approaches aim on genetic input traits. In any case, plant genes are modified either by combination breeding, smart breeding, or genetic engineering.

Combination breeding is the most commonly used breeding method today. Two parent plants are crossed, and by natural recombination the genomes of both parent plants are rearranged and redistributed according to the laws of heredity (first realized by Gregor Mendel (1822–1884); Austria). Subsequent filial generations are cultivated in green houses and analyzed for the quality of the targeted traits. After selecting improved varieties, the breeding process is repeated. As breeders need to cultivate each generation and analyze the targeted characteristic by checking the whole plant, this method is extremely time consuming. It may take 10 years plus 2–4 years for official registration and seed propagation before entering the market.

In addition to this traditional method, plant breeders increasingly use the tools of molecular genetics. The plant genome is sequenced, and molecular markers tagging the desired quality are introduced by smart breeding. The result of genetic recombination becomes much more predictable and by analyzing the genetic markers in the laboratory the desired genetic combination can be identified on cellular level within short time. Plant genome recombination and subsequent selection therefore can be performed much more efficiently.

Genetic engineering also uses selected genome sequences but is able to take advantage of nature's genetic diversity by introducing beneficial genes from other species (plants, bacteria) into the plant genome. In contrast to smart breeding, the resulting varieties are classified as genetically modified (GM). Critics point out that foreign genes in a plant may unfold unexpected effects or cross into wild species in an uncontrollable way. Therefore, release of GM plants is strictly regulated. GM corn, soybean, rapeseed, and cotton are cultivated in South and North America, China, and Southeast Asia but Europe acts more restrictive (Tables 1.20 and 1.21).

1.3.8 Basic Transformation Principles

Vegetable biomass and its compounds are subject to various industrial transformation as described here. Depending on the pretreatment of the raw materials, a distinction is drawn between first-, second-, and third-generation processes and product.

1.3.9 Industrial Use

Besides traditional applications in food, feed, fiber, paper, and construction materials (wood) biomass is increasingly going to deliver raw materials into the main sectors: energy and chemicals, which are discussed in the following section.

1.3.9.2 Chemicals

In many industries, bio-based feedstocks are already established, either because of (i) special feedstock suitability (pulp and paper), (ii) missing alternatives ( proteins, drugs), (iii) unique characteristics (special polymers, tensides, lubricants), or (iv) customer demand (cosmetics). All the following chapters demonstrates that modern bio-based feedstocks conquer chemical markets according to similar rules of the fossil-based chemicals that emerged 150 years ago: Starting from high-value adding pharmaceutical markets where bio-based materials provide the only alternative, the growing knowledge encourages first to enter fine and bulk chemistry markets and finally to compete directly with fossil-based processes. One of the striking differences to the early chemical industry times is the fact, that science and knowledge are key from the very beginning.

Bio-based raw materials like rubber, wood, starch, and vegetable oils are established in various industrial applications. Figure 1.2 presents an overview about the current material use of biomass.

Natural rubber goes into high-performance tires, for example, for heavy-duty vehicles and special applications like medical products. It is a long-chain polyterpene, which is more uniform than its fossil-based synthetic alternative. About 50% of the global rubber production of 25 million tons is provided by natural rubber (van Beilen and Poirier, [2008]).

Cellulose is used to produce fibers like rayon for the textile industry with a volume of 3.5 million tons (Morris, Welters, and Garthoff, [2011]). It is also the basis for paper and cardboard production. More than 500 million m³ of wood is used to make 160 million tons of pulp. As a side product, 50 million tons of lignin appears, only 2% of that material is used for further chemical products (Morris, Welters, and Garthoff, [2011]).

Starch is used to stiffen textiles and increase the mechanical strength of yarns. It goes as filler in very different applications like inks, detergents, and drug tablets. Around 30–40% of the global production of 2.5 billion tons goes into such non-food applications (Morris, Welters, and Garthoff, [2011]).

Soap, perfumes, cosmetics as well as paints, wood treatment products, and hydraulic fluids and lubricants are made from or contain vegetable oils.

1.3.9.6 Polymers

Biopolymers reached a share of 1.6 million tons (0.7% of total polymer market) but are expected to grow to more than 6 million tons in 2017 (European Bioplastics, [2014]; Statista, [2013]). There are two groups of bioplastics: (i) bio-based or partially bio-based nonbiodegradable plastics such as bio-based polyethylene (PE) and polyethylenterephthalate (PET) and (ii) bio-based and biodegradable plastics such as polylactide (PLA) (Table 1.26).

Nonbiodegradable bioplastics
Bio-PA	PTT	Bio-PEE	Bio-PET30
80	110	200	600
Biodegradable bioplastics
PLA	Starch blends	Polyesters	PHA	Cellulose (regenerated)
185	183	175	34	27

PA, polyamide; PTT, polytrimethylene terephthalate; PEE, polyethylethylene; PHA, polyhydroxyalkanoate.

As bio-PE and bio-PET are identical to their fossil-based counterparts, it is easy to use it in established processes without any modification. Therefore, such compounds are called drop-in chemicals. Though on the one hand a perfect drssop-in PE demonstrates on the other a typical obstacle of many bio-based chemicals. Ethylene (28.05 g mol⁻¹), the monomer to be polymerized to PE can easily be made from bio-ethanol (46.07 g mol⁻¹) by dehydration but the stoichiometric product yield is only 0.609 kg kg⁻¹.

In contrast, the fossil-based process reaches a carbon yield of 98 kg kg⁻¹. Obviously, the bio-based process is not cost-competitive as long as biomass feedstock does not offer a significant cost advantage.

PLA is based on the monomer lactic acid (C₃H₄O₂), a natural intermediate of lactic acid bacteria like Lactobacillus, the very same species used in yogurt fermentation. The monomer is produced by fermentation based on sugar (Groot et al., [2011]) but an alternative process using lignocellulosic feedstock is under development (Riesmeier, 2013). Subsequent to lactic acid fermentation all further steps to the polymer are performed synthetically. PLA belongs to the polyester plastics and finds applications in packaging, agriculture, automotive, electronics, and textiles industries. The production capacity is expected to grow to close to 2 million tons by 2020 (Grand View Research, 2014).

1,3-Propanediol (PDO) is another sugar-based monomer. Developed since the 1990s by DuPont (USA), it is commercialized in its polymerized form under the trade name Sorona® and finds application especially in replacing fossil-based polytrimethylene terephthalate (PTT), for example, in plastic bottles. What makes this monomer worth to be mentioned here is its biological production system because PDO is a molecule not known to nature. By combining metabolic reaction chains from S. saccharomyces and Klebsiella in an E. coli cell, this host cell was taught to produce a man-made molecule (Demain and Sanchez, [2012]). Today, the world capacity exceeds 100,000 tons per year (de Guzman, 2013), and from a financial perspective the market is expected to grow from $157 million (2012) to $560 million in 2019 (Rohan, [2014]).

Vegetable oils are also used as precursors in oleochemical synthesis. For example, castor oil is of special industrial value because of the presence of hydroxyl groups on the especially long fatty acid chains of 18 carbons. Long molecular structures give high-performance properties to the resulting polymers to be applied, for example, in sports, aircraft, and medical products. Castor oil is becoming increasingly important in the production of polyurethane plastic, which is an application generally known as natural oil polyols.

In 2004, the US National Renewable Energy Laboratory (NREL) published a study that analyzed bio-based chemicals for their potential in the chemical industry from a technical point of view. It resulted in 12 candidates: 1,4-dicarboxylic acids (succinic, fumaric, and malic), 2,5-furandicarboxylic acid (FDCA), 3-hydroxpropionic acid (3-HPA), aspartic acid, glucaric acid, glutamic acid, itaconic acid, levulinic acid, 3-hydroxybutyrolactone, glycerol, sorbitol, and xylitol/arabinitol. Especially succinic acid draws industrial attention. DSM (Netherlands) and Roquette (France) formed the joint venture Reverdia (France) and Succinity (Germany) has been founded by BASF (Germany) and Corbion Purac (Netherlands).

All these molecules are provided by nature. However, it should be emphasized that the chemical industry to a large extent works with non-natural compounds. Therefore, PDO presents a special future-oriented example because it demonstrates that bio-based processes can provide man-made chemical entities for innovative materials and applications as well. Synthetic biology, emerging since early 2000s, is the principle behind such processes. It provides another example of how basic science is translated into industry.

1.3.10 Expectancy of Resources

As it is the case with fossil feedstock, bio-based raw materials are also not available without any limitation. However, the kind of limitation is different. In contrast to fossil materials, biomass is renewable and regrows continuously. The only limiting factor is the annual growth rate of the biomass source. In principle, vegetable as well as animal biomass is renewable but only plants build biomass through photosynthesis and transform atmospheric CO₂ into carbohydrates according the following chemical equation:

Only vegetable biomass is therefore directly involved in the photosynthetic carbon cycle and should be considered as a major industrial feedstock.

Nature is estimated to produce annually 210 billion tons of vegetable biomass. Most of it is lignocellulose (40–55% cellulose, 10–35% hemicellulose, and 18–41% lignin) with an estimated carbon content of about 50%. Therefore, it can be reasonably assumed that photosynthesis fixes globally about 105 billion tons of carbon.

However, because of economical, ecological, and societal reasons not all biomass is available for human purposes. Sustainably available is biomass from agriculture, forestry, and marine sources. The use of agricultural biomass for industrial purposes has already been established. Today, global agriculture produces 14 billion tons of biomass (containing about 7 billion tons of carbon) annually for providing food, feed, fiber, and a little heat, fuel, and chemistry. A significant share is considered waste and utilized not at all, of only little value or under valued: (i) agricultural side streams like straw, rice husks, corn cobs; (ii) silvicultural materials like branches and saw-cut, and (iii) processing residues like milling or food-processing residues (Table 1.31). These resources are going to be realized for industrial purposes by second- and third-generation processing.

In addition to plant breeding, soil management, fertilization, and plant protection, more efficient harvesting and storage methods will still be improved. Plant breeding alone sets since decades the still unbroken trend of annual crop yield improvement of about 2%. On the contrary, a growing world population (9 billion by 2050) will ask for more food, feed, and fiber. Considering currently neglected resources, yield improvement, and food demand a range of 0.5–1.4 billion tons of biomass has been estimated to be sustainably available for industrial purposes by 2030 (Kircher, [2012]; Bang, Follér, and Buttazzoni, [2009]).

1.3.11 Green House Gas Emission

In the photosynthetic carbon cycle, CO₂ is fixed in biomass and released into the atmosphere again when biomass degrades (or is burned). Theoretically producing and using vegetable biomass should not emit any CO₂. However, plants not only consist of photosynthetic leaves but have roots interacting with the microbial soil flora. Soil management (e.g., tilling) aerates soil thus activating microbial metabolism and the related CO₂ emission further. It is estimated that a CO₂ amount equivalent to about 4% of the harvested biomass is emitted by the microbial soil flora from agricultural areas. Therefore, non-tilling land-management methods have been developed in order to at least reduce this emission. In contrast, if land is not disturbed over longer periods like grassland or forest soil, the microbial soil biomass grows, thus binding carbon up to a volume of about 30% of the grass or wood biomass above ground.

Modern agriculture is based on intensive land management. Farmers use extensive machineries in preparing the soil, seeding, harvesting, processing, storing, and shipping. Today, these machines run mostly on fossil fuel emitting CO₂ equivalent to about 11% of the crop biomass harvest.

Last but not least, the high yields of modern agriculture heavily depend on adding fertilizer to the soil, especially nitrogen. About 2–3% of the nitrogen applied escapes in the form of N₂O into the atmosphere. This small amount appears to be negligible; however, its climate warming impact is 310 times higher than that of CO₂ (Tables 1.27 and 1.28) (Haberl et al., [2012]).

Negative numbers mean that more CO₂ is fixed than emitted.

Methane (CH₄) emitted from paddy fields and released by livestock husbandry (especially ruminants) gives another biomass-related emission with a GHG (green house gas) effect 21-fold more than that of CO₂ (Table 1.28). In Table 1.29, CO₂ equivalents are given, which consider the specific climate impact of different GHGs.

Biomass production does not come without any GHG emission. It is estimated that about 20–50% of global GHGs originate from agriculture, livestock breeding, and forestry (Table 1.28).

1.3.12 Regional Pillars of Competitiveness

Using renewable raw materials implies a significant impact on global feedstock regions and industrial centers. As discussed before, fossil carbon sources are produced in selected and manageable areas and are easy to ship globally through pipelines, tankers, and railroad to industrial centers. In contrast, biomass and processing residues are distributed over very large areas, in fact, over all global agri- and silvicultural areas. Harvesting from the field or forest is costly, and as biomass is degradable it needs special efforts for storage. In addition, these materials are relatively bulky and not suitable for pipelines. They need to be shipped by truck, railways, and ship. For example, 1 m³ straw contains 30–50 kg carbon, whereas the same volume of fossil oil gives 800–900 kg carbon. In other words, to get the same amount of carbon from straw requires the transportation of 23-fold volume compared with fossil oil (Table 1.30).

Because harvesting, storage, and shipping are costly and transportation over large distances is difficult, at least preprocessing will be done close to the raw material production site. Preprocessing may include sugar extraction from sugar and starch crops, release of lignocellulosic second-generation sugar, or gasification to syngas (third-generation feedstock). Most of such carbon sources may be shipped directly to industrial centers. Figure 1.3 shows biomass trade routes to be expected by 2020.

Preprocessing of biomass might trigger the integration of more processing steps, thus adding value to more advanced intermediates. At this stage, the very same pillars of competitiveness, which made early fossil-based industrial regions successful become effective. More sophisticated processes need a skilled workforce, ask for accompanying academic research, require an efficient public infrastructure and administration, and last but not least attract investors. Rural areas concerned will turn into industrial feedstock regions. However, these regions will most probably not see bio-refineries of the scale of oil refineries. Because feedstock transport distances are economically limited, biomass refineries will reach much smaller capacities than big oil refineries. Consequently, the bio-economy is a special opportunity for SMEs.

1.3.13 Questions for Further Consideration

Does bio-feedstock provide an alternative to fossil feedstock? What are the differences?

What are limiting economical, ecological, and societal factors in using bio-feedstock?

What makes a bio-based production site attractive?

1.4.1 Economical Challenges

Energy carriers and chemicals represent an extremely wide range of value. The more specific the function of a molecule is, the more the added value is. For example, a pharmaceutical active addressing a very specific physiological response such as a monoclonal antibody might be valued millions of dollars per kilogram. Astaxanthin, a feed additive giving salmon its typical red color, earns more than $1000 kg⁻¹. However, such molecules reach market volumes of only gram (special pharma actives) or up to 10,000 tons per year and belong to the fine chemicals sector, which makes about 10% of all chemical sales. Specialties are produced in the 100,000 tons range (30% of chemical sales) and bulk products (60% of chemical sales) like monomers for plastics are produced in more than 100,000 and even million tons per year range. In this segment, market prices are in the $1–2 kg⁻¹ range or even lower, and therefore only extremely low production costs are tolerated. Besides capital and running cost, especially cost of feedstock are decisive and can make up to 40–50% of total production cost (Table 1.30). Compared to fossil feedstock renewable carbon sources still struggle on a pure cost basis because of expensive (i) harvesting from large areas, (ii) shipping of bulky materials, (iii) storing of degradable biomass, and (iv) preprocessing. Reducing feedstock cost will be key in realizing the bio-economy (Table 1.31).

1.4.2 Feedstock Demand Challenges

Not only cost but also the required volume is a topic to discuss. The global consumption of coal, oil, and gas is about 13 billion tons. When assuming an average carbon content of about 85% in fossil resources, this means that approximately 11 million tons of fossil carbon is consumed annually.

To replace fossil carbon by agriculture alone, this sector would need to expand by a factor of 2.5 from today – 14–36 billion tons of biomass (equivalent to 18 billion tons of carbon). Even when considering future yield increase by plant breeding, cultivation methods, and bringing more areas on top yield level, it seems risky to seek the solution only in more agriculture, as soil erosion, climate change, and fertilizer shortage (e.g., geological phosphate resources are running out) raise more uncertainties.

Obviously relying on agriculture alone is not enough. Industries need to exploit new sustainable carbon sources such as second-generation lignocellulosic raw materials. They present so-called non-food biomass from agriculture as well as forestry. Such options as well as processing side streams and third-generation carbon sources like CO have been discussed earlier. About 0.5–1.4 billion tons of biomass have been estimated to be sustainably available; a volume obviously not sufficient to replace fossil carbon in total.

Such a conflict asks for setting priorities: The modern bio-economy should be focused on products without an alternative to the use of carbon. These are at first organic chemicals and according to the state-of-the-art heavy-duty fuels such as aeration fuel. Today, organic chemicals consume about 7% (280 million tons containing 238 million tons of carbon) of the total fossil oil production. This gives the theoretical minimum volume range to be satisfied by biomass. In fact, the biomass demand will be significantly bigger as the stoichiometric productivity of bio-based processes is generally lower than that of chemical synthesis, but this number gives an orientation. Compared to the biomass volume, which is currently sustainably available (0.5–1.4 billion tons containing 250–750 billion tons of carbon), it appears appropriate to replace fossil carbon in chemical synthesis and in addition produce some bio-fuel. Power generation and short-distance mobility are not really dependent on carbon sources. These markets may run on solar, wind, geo, thermal, hydro, and more alternative power sources and the storage media required.

In summary, the pressing feedstock challenge asks for comprehensive use of carbon-containing materials and prioritization on products depending on carbon.

1.4.3 Ecological Considerations

It is widely accepted that the climate change is caused by anthropogenic GHG emissions. However, the public debate often focuses only on CO₂ from fossil-based activities though agriculture contributes to the whole set of GHG significantly. Therefore, biomass should be produced and used carefully and as energy- and carbon-efficient as possible. Efficiency means in this context to transform biomass into energy or materials with energy and carbon losses as low as possible. This concept analyzes single production steps and complete utilization chains.

For example, sugar might be extracted from sugarcane. The residual biomass (bagasse) might first be used to produce second-generation sugar and subsequently be burned for generating power (what is today the only use). The last step of sugarcane-based ethanol fermentation is an aqueous solution still containing some organic residues plus minerals (vinasse), which is considered today a waste and spread on the field as fertilizer. Before that last utilization step, vinasse could generate biogas, thus yielding energy from the organic fraction but still retaining the minerals. This concept is called cascade-use because biomass energy and carbon are utilized in consecutive steps as completely as possible. The consistent implementation of that concept addresses not only agricultural biomass but also forestry and marine resources, industrial processing residues, and even municipal solid and liquid wastes.

Besides reducing agro-related emissions cascade-use also helps to optimize the use of biomass cultivation areas. This topic is too broad to be discussed here but nevertheless, in view of the growing world population, it is obvious that land use is critical. This topic is not only about food production but also about keeping soils fertile, avoid salinization and erosion, water management, and maintaining biodiversity.

In summary, the modern bio-economy is on the one hand the only alternative to fossil-based processing with all its implications but on the other does not come without any environmental burden. To find the most beneficial biomass, its way of production and later processing in a cascade mode needs careful analysis through life cycle assessment.

1.4.4 Societal Considerations

1.5.1 First-Generation Processes and Products

December 12, 2014 – Algenol Biofuels (USA, founded 2006) was named the recipient of the 2014 Global Energy Award for Industry Leadership in Biofuels, presented by PLATTS Global Energy Awards. Algenol's algae technology platform for production of the four most important fuels (ethanol, gasoline, jet, and diesel fuel) uses algae, sunlight, CO₂, and saltwater for high-yield, low-cost fuel production. The technology recycles CO₂ from industrial sources.

September 19, 2014 – Lufthansa made commercial flight with bio-based jet fuel. It contained 10% farnesane produced by yeast from sugar. The process was developed by Total (France) in cooperation with the spin-off Amyris of UC Berkeley (USA). In addition, Lufthansa intends to test Jatropha oil-based jet fuel.

September 18, 2014 – BASF (Germany), Cargill (USA), and Novozymes (Denmark) announced a process to produce acrylic acid from renewable raw material. Acrylic acid is a bulk chemical and building block for plastics, fiber, coatings, and superabsorbers (absorbing aqueous liquid, e.g., in diapers). The process produces 3-hydroxypropionic acid by fermentation, which is subsequently transformed into acrylic acid. Suitable carbon sources are, for example, sugar and glycerol.

June 26, 2013 – Sugarcane-based low-density polyethylene (LDPE) will be used in all Tetra Pak packages produced in Brazil. Tetra Pak (Sveden) stated that about 13 billion bio-based packages will be produced in Brazil. Bio-ethylene will be produced from sugar-based ethanol by Braskem (Brazil).

June 19, 2013 – Multilayer tube systems with bio-based polyamides from Evonik Industries were tested in a racing car for the first time. The car boasted a number of novel features including a multilayer line for charge-air cooling. The outer layer was made of a polyamide, which is based on castor oil (extracted from the oil crop Ricinus communis).

1.5.2 Second-Generation Processes and Products

September 29, 2014 – POET-DSM Advanced Biofuels LLC, a 50:50 joint venture of the bio-ethanol producer POET (USA) and DSM (chemistry; The Netherlands), published the first commercial-scale cellulosic ethanol facility in Iowa (USA). It will daily convert 770 tons of biomass into 75 million liters of ethanol.

November 18, 2013 – M&G Chemicals (Italy) announced to construct a second-generation bio-refinery in China for the conversion of 1 million tons of straw biomass into bio-ethanol and bio-glycols. The lignin resulting as a by-product from the bio-refinery will feed a 45 MW cogeneration plant, which will be constructed at the same time as the bio-refinery in the same site.

October 6, 2014 – Energochimica SE (Slovakia) signed an agreement with Biochemtex and Beta Renewables for the construction of a second-generation bio-ethanol plant and an annexed energy block to deliver 55,000 metric tons per year of cost-competitive cellulosic ethanol using non-food biomass as its feedstock.

1.5.3 Third-Generation Processes and Products

November 11, 2014 – The bio-news agency Biofuel Digest voted LanzaTech (USA) the hottest company in bio-energy. This company developed a gas fermentation process to bio-ethanol. Carbon source is gaseous CO directly fed into the fermentation broth to cultivate the bacteria Clostridium. CO might come with industrial flue gas or with synthesis gas from gasified biomass. The process has been successfully tested on pilot scale in a Chinese steel mill. The academic basis has been laid especially at British and German universities.

December 9, 2013 – Evonik Industries (Germany) and LanzaTech (USA) have signed a 3-year research cooperation agreement, which will see Evonik combining its existing biotechnology platforms with LanzaTech's synthetic biology and gas fermentation expertise for the development of a route to bio-processed precursors for specialty plastics from waste-derived synthesis gas. In this route, microorganisms placed in fermenters are used to turn synthesis gas into chemical products. Synthesis gases comprise mainly of either CO or CO₂ and H₂ and can come from a variety of gasified biomass waste streams including forestry and agricultural residues and gasified municipal solid waste.