Evaluation of Biomass Potential of some Australian Native Grasses
RIRDC Publication No. 11/101
RIRDCInnovation for rural Australia
Evaluation of Biomass Potential of some Australian Native Grasses
by Dr. Ian Chivers and Prof. Robert Henry
September 2011
RIRDC Publication No. 11/101 RIRDC Project No. PRJ-004679
© 2011 Rural Industries Research and Development Corporation. All rights reserved.
ISBN 978-1-74254-281-2 ISSN 1440-6845
Evaluation of Biomass Potential of some Australian Native Grasses Publication No. 11/101 Project No. PRJ-004679
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Researcher Contact Details
Prof Robert Henry Dr Ian Chivers Queensland Alliance for Agriculture & Food Innovation (QAAFI) Native Seeds Pty Ltd The University of Queensland 34/148 Chesterville Road St Lucia QLD 4072 Cheltenham Vic 3192 PO Box 133 Sandringham Vic 3191
+61 7 3346 0551 +61 3 9555 1722 +61 7 3346 0555 +61 3 9555 1799 [email protected] [email protected] In submitting this report, the researcher has agreed to RIRDC publishing this material in its edited form.
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Electronically published by RIRDC in September 2011 Print-on-demand by Union Offset Printing, Canberra at www.rirdc.gov.au or phone 1300 634 313
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Foreword
The use of biofuels as alternative fuel sources for combustion engines has attracted considerable attention in recent times. Along with other cellulose-based sources such as timber and algae, grasses are being investigated as a feedstock for biofuel production. Grasses represent major options as energy crops because of their highly developed production technologies. The cultivation of grasses is highly developed as they include the cereals, pasture and turf species. Machinery for planting and harvesting of grain, forage and lawns is very advanced compared to that available for other types of plants. Much of the international work in this area has been based on the use of perennial grasses that are native to the country undertaking the investigation. With the successful overseas development of biofuel production systems based entirely on native grasses, it was decided to investigate the potential of a small group of Australian native grass species for biofuel production. Despite occupying only 5 per cent of the world’s total land surface area, Australia has around 10 per cent of the world’s grass species representing a major source for potential domestication as energy crops.
Perennial grasses offer advantages over annual grasses of being more ecologically sound through reduced soil erosion potential, higher soil carbon retention and sequestration and reduced cost and risk to the producer. Australia has many native perennial grass species that are very long lived, hardy and produce significant quantities of biomass. Australian species are far less likely to become weedy in comparison to introduced species. All of these factors suggested it was worthwhile evaluating a small range of Australian native grass species to determine whether their total dry matter production would be sufficient to make them attractive alternative feedstocks for biofuel generation.
Candidate native grass species were screened, by comparison, at a site in northern New South Wales, with wide variation in performance observed. Four species have been identified with growth rates that make them candidates for further evaluation as biofuel crop species. Many more native species remain to be screened to find candidates for biofuel production throughout Australia. The identified candidates need evaluation at additional sites, and selection to identify superior genotypes within each of those more successful species.
Preliminary conclusions were positive although further research is required before these species can be produced commercially as energy crops. The species identified require testing at multiple sites, and selection to identify superior germplasm for use as energy crops in suitable environments. The suitability for long term use as a perennial biofuel crop needs to be evaluated for each species in longer term experiments. In conjunction with future field testing, laboratory and pilot scale conversion to fuels using new biochemical conversion technologies will identify species with superior value as biomass sources.
This report is an addition to RIRDC’s diverse range of over 2000 research publications and it forms part of our Bioenergy, Bioproducts and Energy R&D program, which aims to meet Australia’s research and development needs for the development of sustainable and profitable bioenergy and bioproducts industries.
Most of RIRDC’s publications are available for viewing, free downloading or purchasing online at www.rirdc.gov.au. Purchases can also be made by phoning 1300 634 313.
Craig Burns Managing Director Rural Industries Research and Development Corporation
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Contents
Foreword ...... iii Contents ...... iv Acknowledgments ...... v Executive Summary...... vi Introduction ...... 1 Objectives ...... 2 Methodology ...... 3 Results ...... 5 Implications ...... 8 Recommendations...... 8 References ...... 8 Appendices ...... 9
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Tables
Table 1: Replicated Plots ...... 5 Table 2: Unreplicated Plots ...... 5 Table 3: Four target species ...... 7
Figures
Figure 1: Oryza ...... 9 Figure 2: Arundinella ...... 9 Figure 3: Themeda ...... 10
Acknowledgments
We thank Allison Wiseman for assistance with field experiments.
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Executive Summary
What the report is about Grasses represent major options as energy crops, because of their highly developed production technologies. The cultivation of grasses is highly developed as they include the cereals, pasture and turf species. Machinery for planting and harvesting of grain, forage and lawns is very advanced compared to that available for other types of plants. Other countries have developed biofuel production systems based entirely upon selections made from their native grass flora, and it was thought worthwhile to investigate a small group of Australian native grass species for their potential to do the same in Australia. Despite occupying only 5% of the total world land surface area, Australia has around 10% of the grass species in the world, and may be a major source of new species for domestication as energy crops. Perennial grasses offer advantages over annual grasses of being more ecologically sound through reduced soil erosion potential, higher soil carbon retention and sequestration and reduced cost and risk to the producer. Australia has many native perennial grass species that are very long-lived, hardy and yet produce significant biomass quantities. Australian species are far less likely to become weedy in comparison to the introduced species. All of these factors suggested that it was worthwhile evaluating a small range of Australian native grass species to determine whether their total dry matter production would be sufficient to make them attractive alternative feedstocks for biofuel generation.
Who is the report targeted at? Biofuel manufacturers, biomass producers and researchers need information on the potential of native grasses as options for bioenergy production. Species are available with potential for production in most parts of Australia.
Background The development of a bioenergy industry based upon grasses requires the identification of species with potential for high biomass production in Australian environments. This project aims to begin the process of selecting from around 1000 Australian grass species, some options for commercial evaluation.
Methods used Species were collected for initial evaluation. Candidate native grass species were screened by comparison at a site in northern NSW.
Results/key findings Wide variation in performance was observed. Four species have been identified with growth rates that make them candidates for further evaluation as biofuel crop species. Many more native species remain to be screened to find candidates for production throughout Australia. The candidates identified need evaluation at additional sites and selection to identify superior genotypes within each of those more successful species.
Recommendations Although preliminary conclusions are positive, further research is required before these species can be produced commercially as energy crops. The species identified require testing at multiple sites and selection to identify superior germplasm for use as energy crops in suitable environments. The suitability for long term use as a perennial biofuel crop needs to be evaluated for each species in longer term experiments. In conjunction with future field testing, laboratory and pilot scale conversion to fuels using emerging second generation biochemical conversion technologies will identify species with superior value as biomass sources.
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Introduction
An investigation of the potential use of Australian native grasses as biomass sources was raised as one of the recommendations of RIRDC report 08/117 ‘Future Biofuels for Australia - Issues and opportunities for conversion of second generation lignocellulosics’. This evaluation was recommended in order to address the R&D area of lignocellulosic biomass availability and sustainability of harvesting, and the associated area of life cycle assessments for techno-economic modelling for conversion technologies in Australia. Furthermore, native grasses have been identified by numerous other countries across the world as offering potential for the production of biomass for energy generation in a manner that is both economical and environmentally sustainable. Significant resources have been spent already, and more are planned, for biomass evaluation of the North American native grass, Switchgrass (Panicum virgatum). Brazil is committed to spending substantial funds on the evaluation of one of its native grasses – Gamba grass (Andropogon gayanus). Additional works are being contemplated in other countries as all see potential applications for their native grasses in the production of biomass for energy generation.
Grasses have numerous advantages as a source of biomass for conversion to liquid fuel, or for combustion direct into electricity, compared to other proposed sources. They are able to produce biomass cheaply, are annual providers of biomass, easily managed, can be harvested using commonly available equipment, can provide biomass in their first year and can serve more than one purpose such as grain or grazing. Also, in conversion terms, they are much easier to process into other fuel compounds than are lignified products such as timber. Research in the United States focus has moved to the study of several of their native grasses and considerable areas are already sown to crops of Switchgrass (Panicum virgatum), as well as areas of Big Bluestem (Andropogon gerardii). In the United States there is also interest in using Chinese Silver grass (Miscanthus sinensis) as a biomass source. The rationale for using a native grass is that it is well adapted to the environment so is less likely to be weedy. In addition, a native grass will tolerate the vagaries of local climates better than an introduced grass, will be adapted to local pests and diseases, will grow on the local soils and will be more accommodating of local fauna.
RIRDC proposed that an evaluation of a range of Australian native grasses be undertaken to determine whether there are species that are capable of producing sufficient biomass at a price that will be competitive with other renewable sources, such as timber and algae. Native Seeds Pty Ltd has contributed to an evaluation at the Lismore Campus of Southern Cross University, with sponsorship from RIRDC. Lismore was chosen, as it presented an opportunity to determine the maximum dry matter production of the various species under conditions that would not be environmentally limiting, especially for warm season species. Whilst this does not provide an evaluation of the potential performance of these species under more limiting environments where they are proposed to be most suited, it does provide a baseline evaluation of the maximum biomass potential of these species.
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Objectives
The project aimed to evaluate the potential for the production of cellulosic biomass from a range of Australian native grasses. It aimed to provide reliable data on the total biomass that can be produced annually from a selected range of native grasses.
The production of biomass as a source of energy (Henry, 2010) has been discussed for many years. One of the potential sources of biomass is grasses. They have been used to produce biomass in Australia, principally sugar cane (Henry and Kole, 2010), and also in other countries where a range of grasses including corn, sorghum and the north American native grass Switchgrass have been used. Life cycle analyses have been undertaken for many of these feedstocks and net energy relationships developed. These analyses need to incorporate total costs of production including the cost of the land required to grow the feedstocks and recent studies in the United States indicate that native perennial grasses growing on less than optimal land can generate strongly positive net energy yields that exceed those from crops such as corn and sorghum . Whilst the native perennial grasses may not yield the same weight of biomass per unit area as do the introduced or annual crops, they produce their biomass at a lower cost and with lower production risks than other crops. Considerable effort is being placed into the development of North American native perennial grass Switchgrass (Panicum virgatum) as a biomass crop, with this grass expected to form a substantial part of the likely expansion of biomass-related production through to 21.3 million hectares of existing agricultural land in the United States.
Evaluation of the similar potential of Australian native grasses for biomass production had not been done and was recommended as part of the RIRDC sponsored report 08/117 “Future Biofuels for Australia – Issues and Opportunities for Conversion of Second Generation Lignocellulosics”. It was also recommended as one of the outcomes of a 2008 RIRDC sponsored workshop which looked at the opportunities and limitations in the use of Australian native flora as biofuel sources. As Australian native grasses are generally adapted to growth on poor, leached soils and are able to survive harsh climatic conditions the potential exists for the growth of these grasses under less than optimal conditions. For this reason they are considered as potentially useful candidates as biomass accumulators for numerous environments including marginal cropping land. If this was an economically and environmentally viable activity for marginal cropping conditions it could offer an alternative land use for landowners that are under pressure to adapt to adverse and changing climatic conditions.
In order to assess the use of these grasses under adverse conditions it is advisable to initially assess them under optimal conditions. This allows for their agronomic potential to be determined without conjecture as to which factor would be limiting production under more limited environments. Later evaluations under site-constrained environments can then be undertaken in the light of what the potential production can be when no constraints are experienced.
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Methodology
The project had two major components. Firstly, a fully replicated comparison of the amount of biomass produced by species for which there was a substantial current level of technology and where existing seed stocks permit a large number of plants to be produced. Secondly, there was a collection and preliminary evaluation of a wide range of novel species which are less well known and for which current seed stocks are very limited. Most resources were allocated to the fully replicated work. The selection of species to include in the evaluation was based on published peer-reviewed research, industry publications and reliable anecdotal views.
The site of the evaluation was at the Southern Cross University site at Lismore, New South Wales. This site was chosen as both cool season and warm season grasses grow well there, excellent soils are available, rainfall is high, irrigation is available if necessary, and technical skills for site establishment and maintenance were present. A non-resource limited site was chosen in order to answer the question “What are the biological potentials of these grasses under conditions where no constraints to growth are experienced?” Without this data it is impossible to determine if Australian native grasses will be able to provide biomass for use in these programs under more limiting conditions. Whilst it would have been ideal to simultaneously evaluate these grasses under various other conditions where environmental conditions are limiting such as previously-irrigated conditions, saline land or marginally productive cropping land, budget limitations permitted evaluation under only one set of conditions. In these circumstances it was most appropriate to evaluate under conditions where the maximum potential biomass can be produced.
The first and major component of the work was the establishment and evaluation of plots of pure stands of each of the various grasses that are available en-masse. Species to be included in this evaluation included Kangaroo grass (Themeda triandra), Tall Oat grass (Themeda avenacea), Wild sorghum (Sorghum leiocladum), Large Tussock grass (Poa labillardieri) and Black Spear grass (Heteropogon contortus). Replicated plots of 3 m by 4 m of each grass were established from tubestock that was grown elsewhere from seed of known origin. Evaluation involved an assessment of survival in the first place as many plants died following transplanting. This is thought to be due to excessive moisture caused by very heavy and constant rainfall causing waterlogging of the site. Once the established biomass was harvested by cutting the plants down to 100 mm above ground level, harvested leaves and stems were then bagged and dried.
The second part of the project was to collect material of a range of species for which there was considered to be some biomass potential but where little knowledge and where few seeds or plants were available. Species included in this group were several other native Sorghum species, some Paspalidium species, Common reed (Phragmites australis) and Cockatoo grass (Alloteropsis semialata). Evaluations in this component were not replicated but provided a guide as to whether the species warranted some further work in subsequent evaluations. Total biomass was determined for each of these candidate species. Information was gathered from a variety of sources about what would constitute the largest of the Australian native grasses. Plant materials of as many of those species as could be obtained were collected and propagated into small tubes. For around half of the species there was sufficient material to provide for three replicated plots, while for the remaining half there was sufficient material for only a single replicate.
A 2000 square metre site was prepared at the Lismore campus of Southern Cross University and covered in weedmat. The first of the tubestock were planted into allocated plots from March to April of 2010 and subsequently maintained. Some species died following transplanting and were clearly not suited to the environment at Southern Cross University.
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Plant spacings within each of the 12 square metre plots varied depending upon both an estimate of the mature size of the plants and the number of live plants available. Plant numbers were monitored, deaths noted and replacements provided, or in some cases entire species had died off and been replaced with alternative species.
Biomass harvests of the most successful species were carried out in early 2011.
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Results
The following tables (Table 1and Table 2) provide the fate of plants and their condition at the end of October 2010.
Table 1: Replicated Plots Species Variety C3/C4 Planting time Fate Current condition
Elymus scaber Oakey C3 Autumn 2010 Dead Replaced
Poa labillardieri C3 Autumn 2010 Dead Replaced
Phragmites australis C3 Autumn 2010 Alive Growing well
Sorghum macrospermum C4 Autumn 2010 Dead Replaced
Sorghum intrans C4 Autumn 2010 Dead Replaced
Bambusa arnhemica C4 Autumn 2010 Alive Growing
Schizostachyum sp Murray Is. C4 Autumn 2010 Alive Growing well
Themeda triandra Local C4 Autumn 2010 Alive Growing well
Themeda triandra Burrill C4 Autumn 2010 Alive Growing well
Paspalidium globoideum C4 Spring 2010 Alive Growing well
Sorghum brachypodium C4 Spring 2010 Alive Growing well
Table 2: Unreplicated Plots Species Variety C3/C4 Planting time Fate Current condition
Sorghum leiocladum C4 Spring 2010 Alive Growing well
Cymbopogon obtectus C4 Autumn 2010 Alive Growing
Sorghum bulbosum C4 Spring 2010 Alive Growing well
Themeda avenacea C4 Spring 2010 Alive Growing well
Arundinella nepalensis C3 Autumn 2010 Alive Growing well
Oryza australiensis C4 Spring 2010 Alive Growing well
Sorghum stipoideum C4 Spring 2010 Alive Growing well
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Biomass Results from Evaluation in April 2011
The four species (Table 3) that proved to be successful at the Lismore site were Common reed (Phragmites australis), Reed grass (Arundinella nepalensis), Native rice (Oryza australiensis) and Tall Oat grass (Themeda avenacea). These species tolerated persistent waterlogging, heavy rainfall and an unusual lack of sunlight. While other species, such as Kangaroo grass (Themeda triandra syn Themeda australis) survived, they did not produce comparable biomass quantities and were not harvested.
Biomass was harvested for plots of those species by removing all of the plant material higher than 100ml above ground level.
Dry matter production per plant was calculated.
Based on the mature plant basal diameter an estimate was made of the likely plant density at maturity of large areas with no supplementary irrigation. This number was then multiplied by the biomass per plant to determine the potential dry matter yield per hectare of that crop.
At the time of harvest the plants were photographed (see appendix), their number noted and all the material above 100 mm height was bagged, dried and weighed. As plant numbers in the end were not the same for each plot the number of plants per plot was recorded. The amount of dry matter produced per plant was calculated.
A potential dry matter yield per square metre was derived by a multiplication of the dry matter per plant by an estimated number of plants per square metre that a mature crop would contain. This number varied widely owing to the different form of each of the plants.
In the case of Phragmites australis, this grass is a rhizome producing type that grows many stems per square metre at maturity which grow vertically from the rhizomes. Mature stands have been observed to grow in a manner similar to bamboo species with very high density once established. An estimate of 100 separate shoots has been applied for this grass which is the mean of several measures made on mature stands in northern Victoria (Chivers pers. comm).
For Oryza australiensis, the basal area of the plants at Lismore was measured and a maximum of two plants per square metre was as much as could be reliably grown on a square metre of reasonably fertile soil.
The other two grasses, Themeda avenacea and Arundinella nepalensis, were of smaller basal area than Oryza australiensis and five plants per square metre was adopted for their ultimate spacing.
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Table 3: Four target species Number Total Estimated of plants biomass Kg DM plants per Date Patch at weight per sq.m. when DM per DM per Species Planted location harvest (kg) plant mature sq.m. ha (T/ha)
Phragmites australis Feb-10 C1 12 0.35 0.029 100 2.92 29.17
Arundinella Unreplicated- nepalensis Mar-10 S 43 10.5 0.244 5 1.22 12.21
Oryza Unreplicated- australiensis Oct-10 T 5 6.15 1.230 2 2.46 24.60
Themeda Unreplicated- avenacea Feb-10 T 21 7.85 0.375 5 1.87 18.69
Yields of these crops indicate they are able to produce significant volumes of material and warrant further investigation. None of the other species included in this experiment produced dry matter in sufficient volume to offer a commercially attractive yield.
What remains unknown from this study and which needs to be evaluated are the following:
1. Are there differences between ecotypes that can be used for selection purposes? For all native grass species studied elsewhere for purposes other than biomass, there has been very significant ecotypic variability. Numerous studies show large variances in dry matter production between ecotypes. This study has not investigated more than one ecotype of a species, other than for Themeda triandra, where two forms were studied. Therefore it could be expected that a thorough and broad collection of the four nominated species would find very significant variance in dry matter production between ecotypes which gives rise to an opportunity to make selections with higher dry matter than those already investigated.
2. How much more yield can be expected in the following year, given that these yields were achieved whilst the plants were still reaching mature size? It is likely that yields will reach their maximum in the second year and remain at that level, as long as normal management is undertaken. This is the normal pattern of growth of perennial grasses and in this case the long- term sustainable yields were not determined. This latter yield will be relied upon in determination of the economics of biofuel production and the use of yield data obtained in this trial needs to be viewed with some caution. More useful and robust data would be obtained by continuing this trial on a broader scale in a wider range of environments and for a longer period.
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Implications
These results show wide variation in biomass potential of the species screened. Some species have biomass accumulation rates that are in the range that would make them candidates as bioenergy crops.
Some Australian native grasses seem to offer potential as biofuel crops and deserve to be evaluated thoroughly.
Recommendations
Further research is required before these species can be produced commercially as energy crops. The species identified require testing at multiple sites and selection to identify superior germplasm for use as energy crops in suitable environments. The suitability for long term cropping as a perennial crop needs to be evaluated for each species in longer term experiments. Laboratory and pilot scale conversion to fuels using emerging second generation biochemical conversion technologies will identify species with superior value as biomass sources.
References
Henry, R.J. 2010 Plant Resources for Food, Fuel and Conservation. Earthscan, London, United Kingdom.
Henry, R. J 2010, ‘Evaluation of Plant Biomass Resources Available for Replacement of Fossil Oil’. Plant Biotechnology Journal, vol. 8, no. 3 pp. 288-293.
Henry R. J & Kole C, (eds) 2010 Genetics, Genomics and Breeding of Sugarcane, CRC Press.
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Appendices
Figure 1: Oryza
Figure 2: Arundinella
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Figure 3: Themeda
10 Evaluation of Biomass Potential of some Australian Native Grasses
by Dr. Ian Chivers and Prof. Robert Henry
Publication No. 11/101
This report outlines how a small range of Australian native grass RIRDC is a partnership between government and industry species were evaluated to determine whether their total dry to invest in R&D for more productive and sustainable rural matter production would be sufficient to make them attractive industries. We invest in new and emerging rural industries, a alternative feedstocks for biofuel generation. suite of established rural industries and national rural issues.
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