Large-scale Bioenergy Production Research Articles

Bioenergy in Europe is unlikely to make a timely contribution to climate change targets

Increasing bioenergy production is a significant component of European efforts to mitigate climate change, but has contested potential for reducing emissions. We use an integrated land system model to explore the effects of large-scale bioenergy production within the European Union on carbon balances. We find that increased bioenergy crop production is likely to cause substantial deforestation and a commensurate loss of associated carbon stocks largely due to displacement of food production from other areas. Deforestation would occur either within the EU if European forests were not protected, or in other parts of the world arising from indirect land use change if European forests were protected. The net carbon benefit of bioenergy production is largely negative, or uncertain, even under the most optimistic levels of fossil fuel replacement, and will not offset initial carbon losses over the coming 50 yr. The growth of intensive agriculture required to satisfy the demand for bioenergy and food will have negative impacts on crucial ecosystem services. Overall, we identify substantial disadvantages to increasing bioenergy production relative to freeing land for natural succession. At best, large-scale bioenergy production is likely to be irrelevant to time-sensitive climate targets.

Linking bioenergy production by agricultural residues to sustainable development goals: Prospects by 2030 in China

Large-scale bioenergy production utilizing agricultural residues (ARs) in multi-paths has potential energy, environmental, economic and social (EEES) impacts. If, how and to what extent these impacts integratively bring sustainability contributions at regional scale remains to be explored. Herein, the EEES impacts quantified based upon a multi-resource-technology-output life cycle framework are reflected as 17 indicators, and linked to the sustainable development goals (SDGs) and their sub-goals to explore the sustainability contributions and trade-offs in 31 Chinese provincial regions by 2030 in three scenarios of ARs availability. Results indicate that the ARs can contribute to 1.86 billion GJ net energy output and 32.1 billion yuan net profit by 2030 in the complete scenario with the highest ARs availability. Attributed to open burning avoidance and fossil energy offset, there are mitigation effects on 11 out of 13 life cycle environmental impact categories, however intensification effects on Freshwater eutrophication and Marine eutrophication. Regional sustainability score closely depends on ARs availability, while does not strictly parallel it. The ARs-abundant regions, such as Heilongjiang, Henan and Jilin, benefit outstandingly from bioenergy production to enhance regional sustainability (especially on SDG1, SDG7 and SDG13). The findings can provide decision-makers with references to soundly boosting agricultural bioenergy development to consolidate regional sustainability.

Mineral carbonation of thermally treated and weathered biomass ashes with respect to their CO2 capture and storage

Five long-term stored biomass ashes (BAs) from beech wood chips, corn cobs, sunflower shells, plum pits, and walnut shells produced at 500 °C were thermally treated at 900 °C and subsequently weathered to evaluate their CO2 capture and storage (CCS) potential by mineral carbonation. A combination of different mineralogical, chemical and thermal analyses was used for that purpose. The BAs studied are highly enriched in alkaline-earth and alkaline oxides (52–91%) and they belong to diverse chemical ash types. The minerals responsible for CCS of these BAs include Ca, K, K-Ca and Ca-Mg carbonates and bicarbonates such as calcite, fairchildite, kalicinite, dolomite, and butschliite. The formation of these minerals is a result of interactions between alkaline-earth and alkaline oxyhydroxides in BA and flue CO2 gas during residual char combustion and especially atmospheric CO2 during BA storage and weathering. It was found that the BAs studied show significant CCS capacity, namely about 19–33% (mean 27%). It was emphasized that the renewable and carbon-neutral biomass also has some extra CCS potential due to the sequestration of atmospheric CO2 during BA storage and weathering. Therefore, the future large-scale bioenergy production in a sustainable way can contribute greatly for decreasing CO2 emissions in the atmosphere and can reduce the use of costly CCS technologies.

Assessment of Natural and Post-Extraction Biomass from Acrocomia totai leaves: a Renewable Source of Energy

The search for cleaner production technologies and sustainable development tools has prompted increasing interest in the use of new, renewable raw materials for biorefineries and energy production. Thus, biodiesel production from the pulp oil (fruit oil) of Acrocomia totai Mart., a species of palm tree, is currently being investigated. However, the bioenergy potential of biomass from different parts of this species is still unknown, and may not be limited to oil from the pulp. Therefore, the aim of this work was to evaluate the leaves of A. totai as a secondary source of lipids and energy. Deciduous and fresh leaves were submitted to the Soxhlet and Bligh & Dyer extractions, and the presence of 1.0 to 5.8% of unsaturated fatty acids was observed by GC-FID analyses. The crude extract (CE) of the leaves was obtained by exhaustive extraction with methanol and then partitioned with different solvents. CE and its fractions were characterized by 1H nuclear magnetic resonance (NMR) spectroscopy, and the thermal properties were determined. The average specific heat of the grease fractions was 2.0 J g−1 K−1 and the calorific value of the polar and non-polar fractions varied from 15.7 to 34.1 MJ kg−1. For the whole leaves, the calorific value of the deciduous leaves was higher than that of the fresh leaves due to their lower water content, as determined by thermogravimetric-differential thermal analyses (TG-DTA) and infrared (IR) spectroscopy. The residual pies from the Soxhlet extractions of the deciduous and fresh leaves were characterized by TGA-DTA and scanning electron microscopy (SEM), revealing a lignocellulosic fibrous material with calorific values of 14.2 MJ kg−1 and 9.3 MJ kg−1, respectively, and an average specific heat of 1.6 J g−1 K−1. These thermal properties are comparable to those of sugarcane bagasse, a widely used type of biomass for industrial large-scale bioenergy production in Brazil. Therefore, these results indicated that it may be possible to harvest the deciduous leaves, a residue from the “macauba” cultivation, for energy cogeneration in biodiesel refineries.

Different pretreatment technologies of lignocellulosic biomass for bioethanol production: An overview

Regarding the supply of fossil fuels, greenhouse gasses emission, global warming, and increasing fuel price; there is a need to find alternative energy resources, which are renewable, environmentally sustainable, and economically viable. Agro-industrial biomass such as sugarcane bagasse, rice and wheat straw, corn stover, and switchgrass, named as lignocellulosic biomass (LCB) which is inexpensive, abundant, renewable, and provides a unique natural resource for large-scale and cost-effective bio-energy production. During the production of biofuels, pretreatment is a necessary step due to the recalcitrant structure of LCB. Various pretreatment methods were employed with a different mechanism of action, feasibility, and practicability to produce high yield biofuels. Since many years ago, the development of an effective pretreatment method has been challenging due to the existence of barriers and obstacles. Besides, each pretreatment method has its advantage and disadvantage, which should be investigated to obtain a higher yield of bioethanol. In this paper, the recent findings regarding the application of various pretreatment techniques such as chemical, physical and biological methods for bioethanol production from LCBs have been reviewed. The limitations of the mentioned methods based on the existing barriers were explained, and the future recommendations were discussed.

Extra CO2 capture and storage by carbonation of biomass ashes

Eight biomass ashes (BAs) produced at 500 and 900 °C were studied to definite their composition, phase transformations, carbonation-decarbonation behavior, and CO2 capture and storage (CCS) potential. Light microscopy, powder X-ray diffraction, scanning electron microscopy, as well as differential-thermal, thermo-gravimetric and chemical analyses were used for that purpose. It was found that most of the BAs studied have high contents of alkaline-earth and alkaline elements represented by carbonates, bicarbonates, oxyhydroxides, chlorides, sulphates, phosphates, and inorganic amorphous material, and such minerals and phases have a key role for CCS by BA. There is an intensive formation of newly formed carbonates as a result of solid–gas reactions between alkaline-earth and alkaline oxyhydroxides and volatile CO2 formed during biomass combustion. Subsequently, additional post-combustion carbonates and bicarbonates are formed by both solid–gas and solid-liquid reactions between the unreacted oxyhydroxides and carbonates in BA and CO2 occurring in air and water during BA storage. The decomposition temperature of carbonates is mostly at 600–900 °C and the mass loss measured in this temperature range approximately determines the CO2 volatilization from the carbonates in BAs. The measured CO2 volatilization (or CCS) for the BAs studied is between 1 and 27% (mean 11%). It was emphasized that the biomass energy can be not only carbon-neutral, but also with some extra CCS potential due to fixation and immobilization of atmospheric CO2 in BA. Therefore, the future large-scale bioenergy production can contribute enormously for reducing CO2 emissions and can decrease or eliminate the application of expensive technologies for CCS.

Life cycle water use of a biomass-based pyrolysis polygeneration system in China

Water is essential for bioenergy production. Characterized as low carbon technology, crop-based bioenergy technology witnesses rapid development, inevitably putting pressure on global water resources. Therefore, it is crucial to carefully assess bioenergy technology’s overall impact on scarce water source for a sustainable bioenergy future. In this regard, this study aims to evaluate the life cycle water use of bioenergy from agricultural residues via the first pilot moving-bed pyrolysis polygeneration system in China. By using a tiered hybrid life cycle assessment, both direct and indirect water use are calculated. Results show life cycle water use is 3.89 L H2O/MJ and agricultural process dominates the total water use. Scenarios analysis shows different feedstock allocation ratios during agricultural production have striking influence on water use intensity. In addition, the choice of feedstock is another important influential factor. Under the 2020 Scenario in China’s 13th Five Year Plan, if all the bioenergy target could be met by polygeneration the estimated annual water use will be 6.6 billion m3, in magnitude up to around ten times the total water consumption in Denmark in 2013. In global scenario of potential feedstock available in 2060, the estimated water use for bioenergy produced by polygeneration will be 179–369 billion m3. Although the water use intensity of bioenergy production from agricultural residues by polygeneration is lower than that for other biomass conversion pathways, it is still higher than water intensity of conventional fossil energy products. Large-scale bioenergy production will have macroscopic effects on water demand. Finally, suggestions such as selecting high water-efficient biomass feedstock and reinforcing water-saving irrigation management to minimize water use in agriculture stage are proposed.

Large-scale bioenergy production: how to resolve sustainability trade-offs?

Large-scale 2nd generation bioenergy deployment is a key element of 1.5 °C and 2 °C transformation pathways. However, large-scale bioenergy production might have negative sustainability implications and thus may conflict with the Sustainable Development Goal (SDG) agenda. Here, we carry out a multi-criteria sustainability assessment of large-scale bioenergy crop production throughout the 21st century (300 EJ in 2100) using a global land-use model. Our analysis indicates that large-scale bioenergy production without complementary measures results in negative effects on the following sustainability indicators: deforestation, CO2 emissions from land-use change, nitrogen losses, unsustainable water withdrawals and food prices. One of our main findings is that single-sector environmental protection measures next to large-scale bioenergy production are prone to involve trade-offs among these sustainability indicators—at least in the absence of more efficient land or water resource use. For instance, if bioenergy production is accompanied by forest protection, deforestation and associated emissions (SDGs 13 and 15) decline substantially whereas food prices (SDG 2) increase. However, our study also shows that this trade-off strongly depends on the development of future food demand. In contrast to environmental protection measures, we find that agricultural intensification lowers some side-effects of bioenergy production substantially (SDGs 13 and 15) without generating new trade-offs—at least among the sustainability indicators considered here. Moreover, our results indicate that a combination of forest and water protection schemes, improved fertilization efficiency, and agricultural intensification would reduce the side-effects of bioenergy production most comprehensively. However, although our study includes more sustainability indicators than previous studies on bioenergy side-effects, our study represents only a small subset of all indicators relevant for the SDG agenda. Based on this, we argue that the development of policies for regulating externalities of large-scale bioenergy production should rely on broad sustainability assessments to discover potential trade-offs with the SDG agenda before implementation.

VOC off-gassing from pelletized steam exploded softwood bark: Emissions at different industrial process steps

Formation of hazardous gases during transport and storage of biomass for large-scale bioenergy production is an important safety concern. While off-gassing has been addressed in numerous studies for raw woody biomass, very few describe it in the context of biomass for bioenergy production pre-treated by thermal technologies such as steam explosion. Volatile Organic Components (VOCs) are expected to be altered by the treatment, but until now there is no research published on VOC profiles of steam exploded materials in industrial scale. In the present study, VOCs emitted from the products were evaluated by sampling from different production steps from steam explosion of softwood bark, and following the production chain including also pelletization. Off-gasses were actively sampled using Tenax TA absorbent and analyzed by GC–MS. The VOC formation dependency of operation and storage conditions at different process steps was evaluated by multivariate statistical analysis. We showed that the different process steps along the production line was the main influencing factor for VOC off-gassing amounts, with highest VOC levels directly after the steam explosion process. Treatment severity mainly altered the relative composition of VOC profiles with more terpenes emitted from milder treatment, whereas more severe treatment shifted VOCs composition to contain more furans, e.g. furfural. In summary, treatment by steam explosion leads to potentially problematic VOC off-gassing profiles from the material, and levels vary considerable along the production line. The findings are important from a fuel handling and working environment perspective.

Book Review: Socio-Economic Impacts of Bioenergy Production

Book Review: Socio-Economic Impacts of Bioenergy Production

Opportunities and Challenges in the Design and Analysis of Biomass Supply Chains.

The biomass supply chain is one of the most critical elements of large-scale bioenergy production and in many cases a key barrier for procuring initial funding for new developments on specific energy crops. Most productions rely on complex transforming chains linked to feed and food markets. The term 'supply chain' covers various aspects from cultivation and harvesting of the biomass, to treatment, transportation, and storage. After energy conversion, the product must be delivered to final consumption, whether it is in the form of electricity, heat, or more tangible products, such as pellets and biofuels. Effective supply chains are of utmost importance for bioenergy production, as biomass tends to possess challenging seasonal production cycles and low mass, energy and bulk densities. Additionally, the demand for final products is often also dispersed, further complicating the supply chain. The goal of this paper is to introduce key components of biomass supply chains, examples of related modeling applications, and if/how they address aspects related to environmental metrics and management. The paper will introduce a concept of integrated supply systems for sustainable biomass trade and the factors influencing the bioenergy supply chain landscape, including models that can be used to investigate the factors. The paper will also cover various aspects of transportation logistics, ranging from alternative modal and multi-modal alternatives to introduction of support tools for transportation analysis. Finally gaps and challenges in supply chain research are identified and used to outline research recommendations for the future direction in this area of study.

Bioenergy and Biodiversity: Key Lessons from the Pan American Region.

Understanding how large-scale bioenergy production can affect biodiversity and ecosystems is important if society is to meet current and future sustainable development goals. A variety of bioenergy production systems have been established within different contexts throughout the Pan American region, with wide-ranging results in terms of documented and projected effects on biodiversity and ecosystems. The Pan American region is home to the majority of commercial bioenergy production and therefore the region offers a broad set of experiences and insights on both conflicts and opportunities for biodiversity and bioenergy. This paper synthesizes lessons learned focusing on experiences in Canada, the United States, and Brazil regarding the conflicts that can arise between bioenergy production and ecological conservation, and benefits that can be derived when bioenergy policies promote planning and more sustainable land-management systems. We propose a research agenda to address priority information gaps that are relevant to biodiversity concerns and related policy challenges in the Pan American region.

Bioenergy Development Policy and Practice Must Recognize Potential Hydrologic Impacts: Lessons from the Americas.

Large-scale bioenergy production will affect the hydrologic cycle in multiple ways, including changes in canopy interception, evapotranspiration, infiltration, and the quantity and quality of surface runoff and groundwater recharge. As such, the water footprints of bioenergy sources vary significantly by type of feedstock, soil characteristics, cultivation practices, and hydro-climatic regime. Furthermore, water management implications of bioenergy production depend on existing land use, relative water availability, and competing water uses at a watershed scale. This paper reviews previous research on the water resource impacts of bioenergy production-from plot-scale hydrologic and nutrient cycling impacts to watershed and regional scale hydro-economic systems relationships. Primary gaps in knowledge that hinder policy development for integrated management of water-bioenergy systems are highlighted. Four case studies in the Americas are analyzed to illustrate relevant spatial and temporal scales for impact assessment, along with unique aspects of biofuel production compared to other agroforestry systems, such as energy-related conflicts and tradeoffs. Based on the case studies, the potential benefits of integrated resource management are assessed, as is the need for further case-specific research.

Forest biotechnology advances to support global bioeconomy

The world is shifting to an innovation economy and forest biotechnology can play a major role in the bio-economy by providing farmers, producers, and consumers with tools that can better advance this transition. First-generation or conventional biofuels are primarily produced from food crops and are therefore limited in their ability to meet challenges for petroleum-product substitution and climate change mitigation, and to overcome the food-versus-fuel dilemma. In the longer term, forest lignocellulosic biomass will provide a unique renewable resource for large-scale production of bioenergy, biofuels and bio-products. These second-generation or advanced biofuels and bio-products have also the potential to avoid many of the issues facing the first-generation biofuels, particularly the competition concerning land and water used for food production. To expand the range of natural biological resources the rapidly evolving tools of biotechnology can ameliorate the conversion process, lower the conversion costs and also enhance target yield of forest biomass feedstock and the product of interest. Therefore, linking forest biotechnology with industrial biotechnology presents a promising approach to convert woody lignocellulosic biomass into biofuels and bio-products. Major advances and applications of forest biotechnology that are being achieved to competitively position forest biomass feedstocks with corn and other food crops are outlined. Finally, recommendations for future work are discussed.

Infrastructure Support for Bioenergy Development in Cities

Worldwide, bioenergy production is increasing. However, there is still a lack of understanding of the types of infrastructural modifications necessary to support further bioenergy development in ways that are both cost effective and environmentally sustainable. This paper provides an overview of the infrastructure support crucial for enabling large-scale bioenergy production in cities. Three waste-to-bioenergy pathways to produce biodiesel from waste oils, syngas from plasma gasification of municipal solid waste (MSW), and bioenergy from algae are reviewed. (i) To produce biodiesel from waste oils, a cost-effective feedstock collection system is key as feedstock cost, including transportation cost, is the single largest contributor to total cost. (ii) To promote the production of syngas from MSW by plasma gasification, a decentralized approach is recommended in the near to medium term. This is because at present, there is still little experience operating large MSW plasma gasification plants. A decentralized approach creates opportunities for public-private partnerships, leading to investments to gain operational experience. Soft infrastructure in the form of a well-developed recycling program or legislation is also necessary to ensure the gasification does not compete with recycling for recyclables. (iii) To produce bioenergy from algae, two infrastructures are vital. The first is infrastructure to integrate wastewater treatment and algae cultivation with nutrients and carbon dioxide recycling. The second is infrastructure to create large surface areas from sides of buildings and/or rooftops that are well exposed to sunlight for algae growth. Provided these infrastructures are in place, the three pathways, combined, have the potential to supply up to 12–16 % of Hong Kong’s electricity demand if converting the energy products from the pathways to electricity. Further, the pathways create new interdependencies between the waste and energy sectors. The interdependencies, while synergistic, could lead to new vulnerabilities such that a failure of one sector will cause a failure in the other as well. Care must be taken when designing systems to minimize this.

Bioenergy production and food security in Africa

Food and energy insecurities are the two greatest problems in Africa. Per capita energy consumption in Africa is less than 10% of that of United States of America while 18 out of 23 countries where starvation and malnutrition are most severe in the world are in Africa. Although various African governments have been making efforts to boast agricultural productivity, crop yields remain very low. Most governments do not even have accurate statistics on the number, location and types of crops produced by smallholder farmers that produce more than 80% of foods in Africa. This makes it very difficult to plan and implement any government support to the farmers. Sub-Saharan African countries have very high potential for production of different forms of bioenergy because the climatic conditions favour production of many energy crops. The big question has always been whether to produce bioenergy from food crops, especially in Africa with high acute food shortages. Large scale production of bioenergy may lead to competition with food crops for land, labour and other agricultural inputs. However, data from various sources indicate that Africa has abundant and underutilized arable land which can be effectively used for mass production of energy crops. Furthermore, shortage of labour cannot be a problem given the present very high rate of unemployment in most African countries. The benefits of bioenergy production in Africa outweigh the possible adverse effects on food security. Bioenergy production will create demand for, and stabilize the prices for crops, thereby increasing the earning of the farmers. This will in turn, facilitate industrialization in other sectors of economy through provision of affordable, renewable and clean energy. In order to minimize possible negative effects of bioenergy production on food security, land allocation for energy crop production can be regulated. Energy security cannot be separated from food security and the two should be seen as complimentary rather than as competitors.

Why large-scale bioenergy production on marginal land is unfeasible: A conceptual partial equilibrium analysis

A transparent and conceptual partial equilibrium model of global land use is used to explore long-term effects of large-scale introduction of bioenergy, under different policy cases. The transparency of the model, and the consideration of clear-cut policies, provides a clear picture of how main mechanisms of land-use competition work, and how they influence the food and bioenergy systems. The model is subjected to a detailed characterization, in which parameters critical to the results and conclusions are detected and their impacts depicted. A large-scale introduction of bioenergy would raise food prices in all cases/scenarios investigated, and relative price increases of extensively produced crops would be at least twice as high as compared to intensively produced crops. Banning production of bioenergy from the most productive land (limiting production to “marginal land”) would reduce this price impact. However, we show that bioenergy is unlikely to ever be produced on any commercial scale only on land of low productivity. The economic incentives would be strong for owners of more productive land to grow bioenergy anyway and out-compete the more costly production on low yielding land. Large-scale deforestation would become attractive in response to increased bioenergy demand, especially for extensive production systems such as grazing.

Assessment of the availability of agricultural residues on a zonal basis for medium- to large-scale bioenergy production in Nigeria

The major agricultural crops grown in Nigeria are millet, yam, cassava, sorghum, rice, groundnut and maize. In terms of area grown (2001–06) the cereals were dominant with sorghum being the major crop grown followed by millet, maize and rice. Agriculture residue availability was based on the 6 zones in Nigeria and included both field residues and processing residues. A number of different scenarios were evaluated whereby Scenario 1 looked at the total potential availability of field residues, Scenario 2 took account of existing uses while Scenario 3 looked at a collection efficiency of 50% of the residues available from Scenario 2.The total amount of agricultural residue available each year was 55.9 Tg per year which equates to a potential energy value of 657.01 PJ. Field residues were the most abundant feedstock available i.e. 38.4 Tg annually compared with 17.4 Tg from processing residues which equated to 452.33 and 204.68 PJ of potential energy respectively. A large proportion of field residue availability (85%) was in the 3 northern zones which represented in excess of 80% of the land area and cereal crops accounted for 88% of field residues available. When competing uses for field residues were included in the analysis under Scenario 2 then the total amount of field residue available was 21.2 Tg which equates to an energy potential of 248.78 PJ. Under Scenario 3 where a collection efficiency of 50% was used residue availability for medium- to large-scale bioenergy production was 10.6 Tg equating to an energy potential of 124.39 PJ.

Coping with complexity: Designing low-impact forest bioenergy systems using an adaptive forest management framework and other sustainable forest management tools

Forest fuel production is a growing industry in Canada and elsewhere, as governments strive to increase energy security and find alternatives to the use of fossil fuels. While forest bioenergy can provide environmental benefits such as renewability and carbon emissions reductions, the industry can also pose environmental risks through increasing pressure on forest resources. Because large-scale forest bioenergy production is relatively new to Canada, much is still unknown about how such an industry might evolve and impact forest ecosystems. These unknowns, along with the cross-sectoral, multistakeholder nature of the industry, make planning for sustainable forest bioenergy systems quite challenging. In this paper, we introduce some of the challenges to creating sustainable systems, and we discuss how sustainable forest management frameworks like Adaptive Forest Management and Sustainable Forest Management Certification can help to meet these challenges. We also discuss the importance of technology transfer to ensuring that the best available knowledge forms the basis for effective standards and management plans. Sustainable forest management frameworks can help to organize, distil and communicate the growing body of research on forest bioenergy production, link policy to practice through the creation of standards, and incorporate provisions for continual learning and system adaptation, all of which are key to the long-term sustainability of the rapidly evolving forest bioenergy sector. Key words: bioenergy, sustainable forest management frameworks, adaptive forest management, certification, standards, technology transfer

Genetic diversity and population structure analysis of accessions in the US historic sweet sorghum collection

Sweet sorghum has the potential to become a versatile feedstock for large-scale bioenergy production given its sugar from stem juice, cellulose/hemicellulose from stalks, and starch from grain. However, for researchers to maximize its feedstock potential a first step includes additional evaluations of the 2,180 accessions with varied origins in the US historic sweet sorghum collection. To assess genetic diversity of this collection for bioenergy breeding and population structure for association mapping, we selected 96 accessions and genotyped them with 95 simple sequence repeat markers. Subsequent genetic diversity and population structure analysis methods identified four subpopulations in this panel, which correlated well with the geographic locations where these accessions originated or were collected. Model comparisons for three quantitative traits revealed different levels of population structure effects on flowering time, plant height, and brix. Our results suggest that diverse germplasm accessions curated from different geographical regions should be considered for plant breeding programs to develop sweet sorghum cultivars or hybrids, and that this sweet sorghum panel can be further explored for association mapping.