ORNL/TM-1999/264 Environmental Sciences Division

Bamboo: an overlooked biomass resource?
J. M. O. Scurlock Environmental Sciences Division Oak Ridge National Laboratory P.O. Box 2008 Oak Ridge, TN 37831-6407 U.S.A.

D. C. Dayton and B. Hames National Renewable Energy Laboratory 1617 Cole Boulevard, MS 3311 Golden, CO 80401 U.S.A. Environmental Sciences Division Publication No. 4963 Date Published: January 2000

Prepared for the U.S. DEPARTMENT OF ENERGY Office of Transportation Technologies EB 52 03 00 0 and Office of Utility Technologies EB 24 04 00 0 Prepared by the OAK RIDGE NATIONAL LABORATORY Oak Ridge, Tennessee 37831-6422 managed by LOCKHEED MARTIN ENERGY RESEARCH CORP. for the U.S. DEPARTMENT OF ENERGY under contract DE-AC05-96OR22464

Contents
Page Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2. What Is Bamboo? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3. Commercial Applications of Various Bamboo Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Physiological Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5. Fuel Characteristics . . . . . . . . . . 5.1 Description of Samples 5.2 Sample Preparation . . . 5.3 Fuel Analyses . . . . . . . 5.4 Wet Chemical Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 .5 .6 .7 10

6. Stand Establishment and Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 7. Productivity of Bamboo in Asia and South America . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 8. Limited Experience with Bamboo in the USA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 9. Potential for New Applications in the Americas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 10. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 11. Contacts for Further Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 13. Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

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Figures
Page Figure 1. Experimental stand (clonal repository) of Phyllostachys bambusoides, cultivar White Crookstem, at the USDA-ARS/ University of Georgia Plant Genetic Resources Conservation Unit in Griffin, Georgia, USA. Culm diameter is about 5 cm. Photograph taken August 1999 by G.R. Lovell, Bamboo Curator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Figure 2. Stand (clonal repository) of Phyllostachys nigra, cultivar Henon, at the USDA-ARS/ University of Georgia Plant Genetic Resources Conservation Unit in Griffin, Georgia, USA. Maximum culm diameter is about 11 cm, although this size has not been achieved in the stand pictured. Photograph taken August 1999 by G.R. Lovell, Bamboo Curator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Figure 3. Stand (clonal repository) of Phyllostachys bissetii at the USDA-ARS/ University of Georgia Plant Genetic Resources Conservation Unit in Griffin, Georgia, USA. Culm diameter is about 2.5 cm. Photograph taken August 1999 by G.R. Lovell, Bamboo Curator. . . . . . . . . . . . . . . . . . . . . . . . 7

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Tables
Page Table 1. Fuel analyses for selected bamboo samples . . . . . . . . . . . . . . . . . . . . . . . . . Table 2. Comparison of selected fuel properties of bamboo with other bioenergy crops Table 3. Wet chemical analysis of selected bamboo samples . . . . . . . . . . . . . . . . . . . Table 4. Previous chemical analysis of bamboo . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5. Reported maximum above-ground productivity of bamboo stands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 10 12 13 15

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Abstract
Scurlock, J. M. O., D. C. Dayton and B. Hames (2000) Bamboo: an overlooked biomass resource? ORNL/TM-1999/264. Oak Ridge National Laboratory, Oak Ridge, Tennessee. 34 pp. Bamboo is the common term applied to a broad group (1250 species) of large woody grasses, ranging from 10 cm to 40 m in height. Already in everyday use by about 2.5 billion people, mostly for fiber and food within Asia, bamboo may have potential as a bioenergy or fiber crop for niche markets, although some reports of its high productivity seem to be exaggerated. Literature on bamboo productivity is scarce, with most reports coming from various parts of Asia. There is little evidence overall that bamboo is significantly more productive than many other candidate bioenergy crops, but it shares a number of desirable fuel characteristics with certain other bioenergy feedstocks, such as low ash content and alkali index. Its heating value is lower than many woody biomass feedstocks but higher than most agricultural residues, grasses and straws. Although non-fuel applications of bamboo biomass may be actually more profitable than energy recovery, there may also be potential for co-production of bioenergy together with other bamboo processing. A significant drawback is the difficulty of selective breeding, given the lack of knowledge of flowering physiology. Further research is also required on propagation techniques, establishment and stand management, and mechanized harvesting needs to be developed.

1. Introduction
It may be observed cynically that every 5-10 years a new “magic feedstock” appears on the bioenergy scene, a new Philosopher’s Stone about which great claims are made concerning its productivity, its ease of integration into existing markets for growing and fuel supply, its life-cycle analysis, and so on. Some of these novel candidate feedstocks may not be so new – they may have been considered and dismissed 20 years ago, or they may be already in widespread use outside the industrialized world. Bamboo is such a candidate, carrying with it a degree of Eastern mysticism: yet remarkably little is known about this entire sub-family of tall graminaceous plants, despite its everyday utilization, mostly for fiber and food, by about 2.5 billion people – over 40% of the world’s population. This review evaluates bamboo as a potential bioenergy feedstock, and tackles some of the myths and facts surrounding it – its “prodigious” productivity, its “disastrous” flowering, its multiple uses, etc. A limited range of bamboo species are characterized with respect to fuel quality, and a number of research recommendations are concluded.

2. What Is Bamboo?
Bamboo is the vernacular or common term for members of a particular taxonomic group of large woody grasses (subfamily Bambusoideae, family Andropogoneae/Poaceae). Bamboos encompass 1250 species within 75 genera, most of which are relatively fast-growing, attaining stand maturity within five years, but flowering infrequently. Dwarf bamboos may be as little as 10 cm in height, but stands of tall species may attain 15-20 m, and the largest known (e.g. Dendrocalamus giganteus) grow up to 40 m in height and 30 cm in culm (stem) diameter. Bamboos are distributed mostly in the tropics, but occur naturally in subtropical and temperate zones of all continents except Europe, at latitudes from 46° N to 47° S and from sea level to 4000 m elevation (IFAR/INBAR, 1991, Tewari, 1992). Asia accounts for about 1000 species, covering an area of over 180,000 km2 (the size of Missouri, half the size of Germany, or about 2% of U.S. total land area). Most of this comprises natural stands of native species rather than plantations or introductions. China alone has about 300 species in 44 genera, occupying 33,000 km2 or 3% of the country’s total forest area (Qiu et al., 1992). Another major bamboo-producing country is India, with 130 species covering 96,000 km2 or about 13% of the total forested area (Shanmughavel and Francis, 1996). Other nations with significant bamboo production and utilization include Bangladesh, Indonesia and Thailand. The taxonomy of bamboos is still poorly understood, at least in part because of the infrequent flowering of many species (at intervals of 30-60 years). Major economic species include the following: Dendrocalamus strictus – native to India. Solid culms, of greatest economic importance in India, where only about 10 out of more than 100 bamboo species are commercially exploited. Used mostly for papermaking and construction. Dendrocalamus asper – thought to be native to Thailand. Thailand intends to propagate plantlets of this species since much of the present edible bamboo shoot production is from natural forests and not sustainable (IFAR/INBAR, 1991). Thyrsostachys siamensis – native to Thailand. Used for construction in both rural and urban areas of Thailand; also cultivated for edible shoots. Phyllostachys pubescens – sometimes described as Phyllostachys edulis. Originally from China, where it occurs extensively (20,000 km2 or 60% of total bamboo cover); introduced to Japan about 1750. The

largest of the Phyllostachys genus, this species is harvested for both poles and edible shoots throughout South-East Asia. This species requires a climate with precipitation of 1200-1800 mm, mean annual temperature of 13-20° C and monthly mean minimum temperatures no lower than freezing (Qiu et al., 1992). Phyllostachys bambusoides – native to China, but extensively cultivated in Japan since 1866. The largest and most commercially valuable of this genus after Phyllostachys pubescens, producing good-quality wood. Hardier and more cold-tolerant than the latter (Chao, 1989). See Figure 1. Bamboo has been neglected or ignored in the past by tropical foresters, who tend to concentrate on timber trees at the expense of traditional multi-purpose woody species such as bamboo and rattan (IFAR/INBAR, 1991). Literature on the dynamics and productivity of natural bamboo stands is meagre, and reports from plantation stands are almost non-existent (Shanmughavel and Francis, 1996). Bamboo has been used for handicrafts and building material in India and China for thousands of years, yet its potential contribution to

Figure 1. Experimental stand (clonal repository) of Phyllostachys bambusoides, cultivar White Crookstem, at the USDA-ARS/ University of Georgia Plant Genetic Resources Conservation Unit in Griffin, Georgia, USA. Culm diameter is about 5 cm. Photograph taken August 1999 by G.R. Lovell, Bamboo Curator. sustainable natural resource management has only recently been recognized. Unfortunately, most bamboo is harvested from forest stands at a rate which exceeds natural growth, so current utilization is anything but sustainable (IFAR/INBAR, 1991; Tewari, 1992).

3. Commercial Applications of Various Bamboo Species
Many Asian species of bamboo have strong, light and flexible woody stems, which lend themselves to applications as a construction material - one of the most notable modern uses being temporary scaffolding poles which are often seen surrounding the most modern of high-rise buildings in Asian countries. Bamboo 2

utilization in South America is modest by comparison, except in certain local areas where indigenous species have been used for centuries, and where some Asian bamboos have been introduced (notably an international project for bamboo housing in Costa Rica). African use of bamboo is more limited and recent, since there are few native species except in Madagascar, although indigenous and introduced bamboo has been used in Kenya for soil stabilization, construction and fuel (IFAR/INBAR, 1991) and in Tanzania for water pipes (Lipangile, 1987). Worldwide commercial bamboo utilization is reported to be 20 million tonnes per annum. It is unclear whether this figure represents dry weight or (more likely) harvested weight at about 15% moisture content – but this number is considered unreliable since about 80% of bamboo is used locally and statistics are hard to obtain. More than half of this amount is harvested and utilized by poor people in rural areas. Total revenues from bamboo and its products were estimated in the 1980s at $4.5 billion (IFAR/INBAR, 1991). Approximately 1500 commercial applications of bamboo have been identified – mostly in Asia, except where noted below. They may be divided up into the following broad categories: Construction and reinforcing fibers – these include agricultural and fishing tools, handicrafts, musical instruments, furniture, civil engineering (bridges, scaffolding poles), domestic building (house frames, walls, window frames, roofs, interior dividers). Paper, textiles and board - (including rayon, plywood, oriented strand board, laminated flooring). Bamboo fibers are relatively long (1.5-3.2 mm) and thus ideal for paper production (El Bassam, 1998). Paper production in China dates back 2000 years, whilst in India, 2.2 million tonnes of bamboo per year are processed into pulp, making up about two-thirds of total pulp production (Adamson et al., 1978; IFAR/INBAR, 1991). At least eight North American suppliers are importing and marketing tongue-andgroove flooring made from laminated bamboo, which is said to be as hard, durable and dimensionally stable as oak or other hardwood flooring (e.g. Plyboo America Inc., Kirkville, NY). Bamboo culms are sliced into strips, which are boiled to remove starch, dried, and laminated into solid boards using urea-formaldehyde adhesives. The boards may be treated with preservatives such as boric acid, before or after laminating, or both, and a darker amber color may be produced by pressure-steaming the bamboo to carbonize it. Although the adhesive tends to emit formaldehyde for a long time after production, the amount of ureaformaldehyde resin in a laminated product is much less than in a panel board product (Environmental Building News, 1999). Food – bamboo shoots of a number of species are a well-known feature of Chinese and other Asian cuisine, generally imported into the USA in canned form (one estimate suggests 30,000 t/year in the early 1990s). Exports from Taiwan are worth $50 million annually, and those from Thailand $30 million, with much of this going to meet Japanese demand. Combustion and other bioenergy applications - a preliminary literature search found no references to the use of bamboo as an energy feedstock, although anecdotal descriptions of bamboo as a fuel are commonplace. Molini and Irizarry (1983) proposed the use of bamboo as a fuel for power generation in Puerto Rico in preference to sugar cane, since its lower moisture content at harvest obviates the need for drying, but they provide few data in support of their case. Limited experience has been gained using de-lignified bamboo pulp as a substrate for ethanolic fermentation (Ram and Seenayya, 1991). Early work on preparing a diesel-like fuel from bamboo culms (Piatti, 1947) is cited by Tewari (1992); the process appears to have been the pyrolysis of “black liquor” from bamboo pulping, but does not seem to have progressed beyond the laboratory scale (Piatti, 1947).

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4. Physiological Characteristics
Bamboos vary across a wide range of physiological characteristics, so the following information is merely illustrative, and mostly concerns the tall bamboos of likely interest as biomass resources. In general, bamboos can be classified as sympodial (clumped) or monopodial (spreading): tropical bamboos are sympodial, whereas temperate species can be of either category (El Bassam, 1998). Although some bamboos can adapt to varying environments, most require relatively warm and humid conditions (e.g. mean annual temperature of at least 15-20° C and annual precipitation of at least 1000-1500 mm). Shoot buds appear as swellings on the side of the underground rhizomes, which generally occupy the top 30-50 cm of soil and may spread for tens of metres. With the onset of warm spring weather, the bud lengthens and develops into a compact upright shoot which forms a sharp point and penetrates the ground surface. After emergence there is little radial growth of the shoot, with “growth” taking the form of massive elongation of internodes, as much as 0.5 m/week in the case of tall bamboos, until the shoot is the approximately the same height as the rest of the stand. At this point, sheaths are shed and leafy branches emerge from the internodes near the top of the shoot. Further growth over the next few years comprises thickening of the walls of the stem and increases in wood density (Sturkie et al., 1968). Compared with other tall flowering plants, this pattern of growth may give a misleading impression of high productivity – in fact, all that may be observed is an (albeit rapid) re-distribution of previously stored reserves. The reported leaf area index of mature stands is generally high, e.g. 8.02 for P. pubescens (Qiu et al., 1992) and 11.6 for P. bambusoides (Isagi et al., 1993). Such a dense canopy may absorb up to 95% of incident solar radiation (Qiu et al., 1992). The reported pattern of leaf fall for most bamboos is semi-deciduous, with leaves shed at the end of the growing season (e.g. Bambusa sp. growing at Auburn, Alabama; Sturkie et al., 1968) or during the following growing season. P. pubescens renews its leaves on a 2-year cycle, with most leaf fall taking place in the spring, beginning with the second growing season after shoot emergence. This biennial pattern of leaf renewal may be reflected in a biennial pattern of shoot emergence, with alternating “good” and “poor” years of new shoot production (Qiu et al., 1992). The pattern of flowering in bamboos varies with species. A few (e.g. Bambusa atra, native to the Andaman Islands of the eastern Indian Ocean) are known to flower frequently, even annually. Others, such as Bambusa vulgaris, flower a few culms at a time. However, the majority – for example, Dendrocalamus strictus – display gregarious flowering, whereby an entire clump at one location produces flowers and then dies back over the course of 2-3 years. This happens typically every 30-40 years (more than 60 years in some cases), and is therefore observed quite rarely, so the physiology of flowering is still little understood. Clear-cutting does not appear to halt stand mortality, although some species can be induced to develop new shoots for a year or two before finally dying altogether. As a consequence of the rarity of flowering, the taxonomy of bamboos is still confused and based largely on vegetative features such as leaf anatomy, arrangement of vascular bundles in leaf sheaths and culms, etc. (Tewari, 1992). A few genera, e.g. Phyllostachys and Arundinaria, have been reported to recover after flowering (Tewari, 1992). For example, P. bambusoides collected from China in 1926 and grown at Byron, Georgia, USA, began to flower in 1989, but recovered with vigorous vegetative growth by 1993 (G.R. Lovell, pers. comm.). The threat of catastrophic flowering need not pose an economic problem for bamboo growers, as long as uneven-aged propagation material is maintained, and entire stands are replaced before they approach flowering age. 4

Unlike other highly-productive members of the Andropogoneae/Poaceae family (e.g. sugar cane, switchgrass, miscanthus), the entire bamboo sub-family (Bambusoideae) lacks the C4 photosynthetic pathway and anatomy (Jones, 1985). In the absence of this feature (which may lead to higher water-use and nutrient-use efficiencies under high light conditions), the maximum possible productivity of bamboos such as P. pubescens is unlikely to greatly exceed that of other bioenergy crops with C3 photosynthesis such as short-rotation willow coppice.

5. Fuel Characteristics
5.1 Description of Samples
Nine bamboo samples were obtained from G.R. Lovell, Bamboo Curator for the U.S. Department of Agriculture Agricultural Research Service (USDA-ARS) at the University of Georgia Plant Genetic Resources Conservation Unit in Griffin, Georgia. Three different ages of three different bamboo species were sampled for analysis to determine the fuel characteristics of the bamboo samples in relation to other biomass feedstocks with potential for electricity and fuel production, and to determine how the fuel properties change as the plant grows under carefully controlled conditions. What follows is a description of each of the bamboos analyzed. All bamboo stands were established on Norfolk Loamy fine sand soils with slight slope (< 5°), following their transfer from Savannah, Georgia, around 1978. Phyllostachys nigra, cultivar Henon (Figure 2): These rhizomes originated in Nagasaki, Japan and were obtained in 1909 from a Japanese bamboo grower by W.D. Hills, an agricultural explorer. This monopodial bamboo grows to a maximum height of 20 m with an 11 cm culm diameter, and is a much larger cultivar of the common black bamboo species whose culms do not turn black. It is cold hardy down to -20º C, has dense dark green foliage and a gray waxy film on many culms that makes this species a striking ornamental plant. It also has straight, strong culms that make it useful for construction purposes. 1, 2, and 4.5-year-old samples of this bamboo species were obtained.

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Figure 2. Stand (clonal repository) of Phyllostachys nigra, cultivar Henon, at the USDA-ARS/ University of Georgia Plant Genetic Resources Conservation Unit in Griffin, Georgia, USA. Maximum culm diameter is about 11 cm, although this size has not been achieved in the stand pictured. Photograph taken August 1999 by G.R. Lovell, Bamboo Curator. Phyllostachys bambusoides, cultivar White Crookstem (Figure 1): Rhizomes were collected near Yeunguk in the Lungtau Mountains of the Peoples Republic of China in 1926 by F.A. McClure, an agricultural explorer with the U.S. Bureau of Plant Industry. This monopodial bamboo grows to a maximum height of 11 m with a 5 cm culm diameter, and is cold hardy to -18o C. This cultivar differs from the common form in having culms that are curved in a serpentine manner at the base. It also has deposits of white powder on the culms which persists and often completely obscures the green color in older culms. 1, 2, and 4.5-year-old samples of this bamboo species were obtained. Phyllostachys bissetii (Figure 3): Rhizomes were collected from Szechuan Province, Peoples Republic of China, in 1941 by John Tee-Van of the New York Zoological Society. This bamboo grows to a maximum height of 7 m with a 2.5 cm culm diameter. With a cold hardiness of -23o C, it is one of the most cold hardy samples cultivated by the USDA-ARS, and is the first to send up shoots in the spring - it is also the fastest growing and the most invasive. This bamboo is named after D. Bisset, the Superintendent of the USDA Plant Introduction Station at Savannah, Georgia, from 1924 to 1957. 1, 2, and 4-year-old samples of this bamboo species were obtained.

5.2 Sample Preparation
The following preparation was performed to obtain samples which were representative of each bamboo stand. Each of the nine bamboo samples comprised 6-9 representative culms with 2-3 nodes. Culms were split into pieces 1.3 cm wide using a knife or wood chisel, and cut into blocks about 7.5 cm long to facilitate milling. Approximately one half of each sample was processed whole, meaning that the nodes and internodes were milled together. The other half of the sample was separated into node samples and

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Figure 3. Stand (clonal repository) of Phyllostachys bissetii at the USDA-ARS/ University of Georgia Plant Genetic Resources Conservation Unit in Griffin, Georgia, USA. Culm diameter is about 2.5 cm. Photograph taken August 1999 by G.R. Lovell, Bamboo Curator. internode samples prior to milling. The node samples included the complete node plus less than one inch of culm on either side of the node. Each internode sample contained all of the pieces of culm not used in the node sample. Overall, 27 analyses were performed, representing whole bamboo, nodes and internodes for each of the 9 samples listed earlier. Milling and homogenization was performed to assure that the chemical analysis was performed on material which represented that average of each sample. Samples were milled using a Standard Whiley knife mill with a 2 mm screen. Material 20 mesh was milled until it passed the 20 mesh screen. The