There are four types of sorghum grain, sweet, forage and fiber. Compared to other crops potentially used for energy sweet sorghum shows a much wider adaptability to different environments and soil conditions, is resistant to drought and has a higher water and nutrient use efficiency. A mayor disadvantage, however, is the short harvesting window and the poor storability of the stalks that could critically affect the ethanol production costs. Several studies sawed that managing the plant density and row distance could be an important option for improving productivity and adaptability of sweet sorghum especially in short season areas. Since sorghum can be grown in diversity of ecological zones it is difficult to outline a common cultural method but in general, requires a daily temperature above 10 ^oC. Although that it is possible to cultivate sweet sorghum even under no-tillage farming systems it has been demonstrated that the adequate depth is about 2.5 and 3.5 cm. Moreover, the implementation of good agricultural practices, adequate management of soil fertility and water, crop rotations and the use of high quality seeds contribute to an increased resistance to pests. Sweet sorghum can be considered susceptible to Lepidoptera attacks which damage the stalk level. This has as result up to 30% sugar losses.

Although that N increase biomass yields, is reducing the sugar content in the stalk juice. An interesting way of reducing N needs is to rotate the sorghum with legume crops. It was demonstrated that the fixed N by a preceding soybean crop accounted for 35-40% of the improved yields of sorghum. Sweet sorghum maximizes its productivity under well water conditions nonetheless it is very impressive to see its ability to grow under suboptimal conditions. Irrigations trials indicated that the sugar concentration in sweet sorghum stalks did not change significantly by the stress level or the irrigation frequency but from the irrigation methods.

Generally the sweet sorghum produce a poorer quality juice when harvested too mature, mainly because the starch in the juice increases as the plant become senescent. The maximum sugar extraction, for several varieties, must be done between 20 to 40 days. The limited time constitutes a management problem that have to be sold as the current available harvesting equipment is not appropriate. However, some prototypes that harvest, press and collect the juice in a single pass have been tested with promising results. Moreover, the high moisture content influencing heavily the transportation cost but the main problem is to reduce sugar losses on storage. Some studies indicate that sulfur dioxide could preserve sweet sorghum stalks.

To conclude, according to the paper, sweet sorghum is a very interesting energy crop for bioethanol production. It could be used as a multipurpose crop thanks to its stems rich in structural and non-structural sugars, which can be processed into first and second generation bioethanol. Although, without proven successfully crop-management technologies and established markets, it is unlikely that farmers may be attracted to grow it.

Source: Walter Zegada-Lizarazu, Andrea Monti*

Department of Agroenvironmental Science and Technology, University of Bologna, Viale G. Fanin 44, 40127 Bologna, Italy,

b i o m a s s and b i o e n e r g y xx x ( 2 0 1 2 ) 1 e1 2

The quantitative and qualitative production of sweet sorghum strongly depends on the use of appropriate and improved agronomic management techniques which is, in some aspects, still largely unknown, since it is, in many aspects, still a wild species. The challenges faced by the producers could be summarizes in the following points:

• Research on the agronomic management of sweet sorghum for bioethanol purposes, however, has faced alternating periods of increasing and decreasing interest according to the fluctuations on international fossil fuels prices and availability.
• Short harvesting window (limited to about 20-40 days) and the poor storability of the stalks that could critically affect the ethanol production costs.
• Even though sweet sorghum benefits from a wide planting density (narrow rows result in higher stalk and sugar yields and improved control of weeds), ranging from 12 to 20 plants m², finding the appropriate density and seeds of improved cultivars for that density could be problematic. Information on seed production and supply chains is not readily available and seems that seed production at commercial level is in its early stages of development.
• In the environments exposed to high evaporation rates and low fertility conditions, low plant densities may reduce the stand water use efficiency as large quantities of water may be lost as direct evaporation.
• However, at closer planting spacing, plants produce thinner stems with slightly more tillers and if the growing areas are dominated by strong winds and thunderstorms, the risk of lodging increases. Proper availability of potassium may be an effective management practice to add strength to the stems and reduce the lodging problems.
• In the temperate regions of the northern hemisphere sweet sorghum is usually sown in springtime and harvested in late summer or early autumn. At these latitudes early spring or late winter sowing is not feasible as sweet sorghum does not tolerate cold stress. Moreover, seedlings sowed too early develop very slowly making weed control more difficult and costly. Delayed harvests leads to reduced oBrix and stem sucrose contents.
• Even though Sorghum is a resilient species and pests do not cause serious damages to the crop, especially in temperate climates, it can be considered susceptible to Lepidoptera attacks. The main damages by Lepidoptera are at the stalk level where the cavities created by the larvae result in a significant yield loss and sometimes cause lodging or even the death of the plant. Juice quality may be also affected by the level of infestation. Different infestation levels can result in as high as 30% sugar losses.
• Another damaging insects for sorghum are the Aphids that feed on the underside of the leaves and inject toxins that destroy leaf tissues, and can be also vectors for diseases. Chemical treatment may be needed, but most varieties are sensitive to organophosphorus pesticides, so appropriate aphid control should be sought.
• Sweet sorghum seeds should be treated with insecticides and fungicides before sowing to prevent seed rots, seedling blights and sucking sap insects. At the leaf level this crop is susceptible to a number of diseases including anthracnose (red stalk rot), fusarium, maize dwarf mosaic and other viral diseases. Since no fungicides are labeled for sweet sorghum, these diseases could be controlled, to a limited degree, by using resistant varieties, planting disease-free seeds, and by crop rotations with sunflower, cowpea, maize or soybean. Anthracnose can be avoided by growing sorghum in dry environments that are unfavorable for the disease.
• Sweet sorghum’s productivity can be seriously affected, if drought stress occurs at a specific growth stage. For example, the yield reduction was only 1% in post-anthesis drought stress, but up to 36% when drought stress occurred during vegetative growth.
• The juice quality, expressed as total dissolved solids, decreases with the highest fertilization level. High levels of N fertilization may enhance the vegetative growth thus reducing the sugar concentration in the storage organs as it generally occurs in other sugar crops.
• The limited storability and fast decaying of the harvested material, and therefore the limited time for its transportation and processing, are factors that severely affect the sweet sorghum production system. Moreover, the high moisture content (approx. 70%) limits the amount of biomass that can be carried out in a truck load, influencing heavily on the transportation cost, especially over long distances.
• Although studies indicated that sulfur dioxide could preserve sweet sorghum chopped stalks for about three to four months without sugar deterioration, a disadvantage of using large amounts of SO2 would be the management and application difficulties due to the toxicity of SO2 which is classified as hazardous material for human health and highly contaminant to the environment.

References

1. Zegada-Lizarazu W, Monti A, Are we ready to cultivate sweet sorghum as a bioenergy feedstock? A review on field management practices, Biomass and Bioenergy (2012), doi:10.1016/j.biombioe.2012.01.048
2. P.S. Nigam, A. Singh / Progress in Energy and Combustion Science 37 (2011) 52e68 doi:10.1016/j.pecs.2010.01.003

As an energy crop, sweet sorghum has the unusual advantage of being a source of sugar, starch and cellulose. Naturally, the major driver of interest in the plant, both for food and fermentation, has been the large amounts of sugar in its juice, generally comprising anywhere from 20 to 50% of the whole plant’s dry weight. The fermentable sugars are primarily sucrose, glucose and fructose.

The potential fermentation products of sweet sorghum are wide ranging; ethanol, acetone, butanol, various lipids (lipids are most commonly intended for biodiesel production), lactic acid, hydrogen, and methane. Several potential native products of the plant, in addition to cellulose for paper production, are also identified: waxes, proteins, and allelopathic compounds, such as sorgoleone.

The grain of sweet sorghum can be processed according to typical grain fermentation procedures, which generate spent grain and solubles. It was demonstrated that the solubles could be concentrated using ultrafiltration and reverse osmosis to generate, along with the spent grain, a high protein feed. Waxes from sorghum grain may be used for food coatings and have been used in the production of biodegradable and edible films.

It is possible to ferment sweet sorghum sugars, by ubiquitous microbes, to hydrogen, followed by anaerobic digestion of the remaining biomass to biogas. In a study, 90% volatile solids conversion efficiencies were achieved over a 75-day solids retention time. Pretreatment techniques have been also used to increase the saccharides available for hydrogen production. Additionally, some hydrogen-producing microorganisms have been shown to convert both pentose and hexose saccharides, allowing for the conversion of hemicellulose to hydrogen.

Some products may be available for extraction prior to fermentation, or may be generated from the bagasse. The bagasse itself, although not a good soil amendment in its raw state, can be converted into useful compost. The pith from sorghum bagasse has been converted into activated carbon for the manufacture of electrodes in supercapacitors. Sorghum bagasse can also be used to produce syngas and bio-oil, via pyrolysis.

Solvent extracts of sorghum have been shown to inhibit the activity of α-glucosidase and human salivary α-amylase, and so there may be sorghum compounds of use in diabetes treatments.

Lastly, the allelopathic nature of the sorghum plant has been observed and recently, purple nutsedge weed growth suppression has been demonstrated using solvent extracts of sorghum. Some studies have identified potential allelopathic compounds, such as the root exudate sorgoleone and the induced defense compound dhurrin (p-hydroxy-(S)-mandelonitrile-β-D-glucoside). Sorgoleone levels vary widely among varieties, but it is hydrophobic, selective in action, effective at extremely low concentrations and so could have commercial applications.

In the following table, various products and the micro-organisms used, during the fermentation of sweet sorghum, are presented.

References

• M.B. Whitfield et al. / Industrial Crops and Products 37 (2012) 362– 375 doi:10.1016/j.indcrop.2011.12.011

The speakers and topics cover a variety of topics covering sorghum use for renewable energy.  Ed Wolfrum, National Renewable Energy Laboratory, will speak on compositional analysis and Randy Powell, BioDimensions Delta BioRenewables LLC, on first generation processing.

Agronomics and development will be covered with Jeff Dahlberg, University of California Kearney Agriculture Center speaking on agronomics and Bill Rooney, Texas A&M, addressing sorghum breeding for renewables. The logistics of harvesting, hauling and delivering will be covered by Bob Avant, Texas A&M. The state of sorghum technology will be covered by Larry Richardson, Richardson Seeds Ltd.

source: http://www.ethanolproducer.com/articles/8691/

The Gaia Association, a non-governamental and no profit organisation, has receiving financing from the World Bank to demonstrate the feasibility of producing bioethanol on small-scale to be used as fuel locally.

The project will install an efficient ethanol microdistillery (EMD) in the outskirts of Addis Ababa, Ethiopia. Gaia Association intends to apply part of the grant towards the procurement of one Ethanol Microdistillery to be installed in the outskirts of Addis Ababa, Ethiopia.

The goods to be supplied include one ethanol microdistillery able to produce 1,000 litres per day of hydrous and/or industrial grade ethanol at 92 – 95 per cent v/v based on molasses feedstock.
The microdistillery should also be able to handle other feedstocks as deemed feasible, including sugarcane juice and fruit waste from local markets.
The final bioethanol produced will be used in the local community as fuel for stoves, small engines, and other utility purposes.

The EMD will ultimately be owned by a women’s association, whose members are among the poorest in the city, with an average income of below $12 USD per month.

This is very important for bioethanol production in decentralised way, using also wastes of local production.

SOURCE : http://www.thebioenergysite.com/news

Alternative uses of sorghum encompass utilization of grain and sweet stalk in food and non-food sectors forth production of commercially valued products, such as alcohol (potable and industrial grade), syrups (natural and high fructose), glucose (liquid and powder), modified starches, maltodextrins, jaggery, sorbitol and citricacid (downstream products from starch).

In India

In India, sorghum is traditionally consumed in the form of unleavened flat bread (roti). In southern India, it is consumed in the form of sankati, annam and ganji (thin porridge). Popped sorghum and sorghum noodles are eaten as breakfast or snack foods. The possible promising alternative food products from sorghum are bakery products, maltodextrins as fat replacers in cookies, liquid or powder glucose, high fructose syrup and sorbitol. Malted sorghum can be a good alternative for baby weaning foods.

The industrial products made from sorghum grain include alcohol (potable grade) and lager beer. Commercialization of alcohol production from grain is already in practice. Other technologies such as production of glucose, maltodextrins, high fructose syrup and cakes from sorghum are yet to be scaled up. The sweet sorghum with its juicy sweet stalk is used as a bio-energy crop. Sweet sorghum products like syrup and jaggery have received good attention from dry land farmers. Attempts for scaling up the technology for alcohol production from sweet sorghum were successful, but more work is needed to integrate the current production with potential market.

In China

Since ancient times sorghum grain has been used in China as food and as raw material for Chinese liquor, starch, vinegar and caramel. There are many traditional sorghum foods in China, with various processing methods. According to Zhao Shukun (1987), it was found that there were a round 40 traditional sorghum foods, which could be sorted in to three groups based on raw materials and processing methods: polished grain foods, flour foods and popped foods. Chinese sorghum beer was first made with sorghum as main raw material in the Institute of Sorghum, Shanxi Academy of Agricultural Sciences in early 1980s based on traditional technology for barley beer. Popped sorghum is a newly developed food in recent years. Crisp and popped sorghum made with special popping machine is popular. Sorghum pigment (red) is chemically a derivative of flavones – like compound, which is a natural pigment with no toxicity or flavour. Usually it is a red powder or lumpy solid, and can also be processed in to liquid o r paste as needed. It can bed is solved in water. Sorghum pigment can be widely used for colouring processed me at and fish, soy bean products, cake, drinks, candy, medical capsules, etc.

Because sorghum is not as popular as rice and wheat, and seed companies are reluctant to manage sorghum seed, it is not easy for farmers to get new sorghum varieties or relevant technologies that are desired. Sometimes research results cannot meet requirements of winery. So it is necessary to establish a coalition of research institutes, producers and processing companies.

In Pakistan

Sorghum is mainly consumed as a food grain (87%) while only 5% of it goes into feed. Sorghum is the most important summer fodder crop with increasing importance in the irrigated areas near towns. Like many developing countries, the available data on production and utilization of sorghum in Pakistan are less accurate because these are primarily grown in outlying areas as subsistence crops. Also, in the hot and dry agro-eco regions, they are grown as dual-purpose crops, where both grain and stover are highly valued outputs. Currently sorghum and millet, each contribute about 3% of the cereal area and slightly less than 1% of cereal production. Before the development of commercial poultry feed industry, the grains of these crops were basically used to feed livestock and rural poultry.

In Thailand

Methods and feasibility on alternative uses of sorghum in Thailand are discussed. The use of sweet sorghum for ethanol production is proposed. Sorghum (Sorghum bicolor) is an important cereal crop grown in Thailand and ranks third following rice (Oryza sativa) and maize (Zea mays). It is cultivated for its grain and primarily used for animal feeding. There are four classes of sorghum commonly grown in Thailand: grain sorghum, fodder sorghum, sweet sorghum and broomcorn. Major emphasis is on grain sorghum production. In Thailand, sorghum grain is primarily utilized for the livestock feed industry. However, high tannin sorghum grains are not efficiently utilized by monogastric animals. Recently, the Thai government promoted the use of gasohol (gasoline +10% of 99.5% ethanol) and also tried to promote the use of diesohol (diesel+10% ethanol) in the future.

Of the raw materials, ie, rice, cassava (Manihot esculenta), sugarcane, molasses and sweet sorghum for producing ethanol in Thailand, only cassava and molasses were cost effective Use of cassava and molasses as raw materials for producing ethanol can generate more income than selling as cassava chips, cassava pellet s and raw molasses. Production of ethanol from rice and sugarcane will decrease the value of the crops. Many experiments on sweet sorghum production have been done at Khon Kaen University, Thailand. It is already proved that sweet sorghum is one of the suitable crops for use as an energy resource.

Source: Alternative Uses of Sorghum and Pearl Millet in Asia, Proceedings of the Expert Meeting, ICRISAT, Patancheru, Andhra Pradesh, India, 1-4 July 2003

The additional mechanism available to these plants helps them survive in warm, with plenty of sunshine habitats, where water availability is limited. That is why the sweet sorghum plant stands in soils with limited irrigation.

Although the cultivation of sweet sorghum represents multiple advantages, for a farmer, disadvantages of the particular crop must seriously be considered. Specifically:
• Soil humidity: Depletes soil humidity and soil nutrients leading to degrading its structure.
• Crop residues: The crop residues from cultivation encourage the soil microorganism’s growth that competes with future cultivations for nitrogen (N). Therefore as a culture can follow any other cultivation, does not apply with those who follow the cultivation of sweet sorghum in a crop rotation.
• Allelopathy: Crop residues of certain varieties effect the development of some cultivated crops.

These mean that a proper crop rotation must be design in order to avoid problems to crops following by the sweet sorghum cultivation. The cultivation of sweet sorghum is recommended not to exceed two continuously years.
The choice of leguminous crops as soil improvers such as alfalfa, clover, vetch etc, where they will alternated with linear cultivation of sweet sorghum, so that benefits the last and enhance the fertility and health status of the soil, is an excellent option for the crop rotation.

Source: PhD Thesis: Photosynthetic characteristics of representative plant species of the Mediterranean ecosystem – Sally Alloh Sumbele.
Dimas Kitsios, Associate Professor, School of Agricultural Technology, A.E.T.I, Thessaloniki

As stated in its official presentation, the objective of Master TAPAS is to develop knowledgeable specialists in technology management and development for the sustainable production of farming systems, fostering their technical education and research abilities. Teaching and training program is organized into five modules: I, Methodology for analysis of agro-systems, II, Quality and degradation of agro-systems, III, Agricultural technology for sustainable production, IV, Advanced seminars and V, Final Thesis for the Master’s degree.

Bioenergy and plant species for a sustainable development of bioenergy (in short, ‘Bioenergy’) are the subjects of one out of the four courses offered in Module III of Master TAPAS, and the research group GA-UPM is the responsible for this course. It is worth mentioning that the overall objective of GA-UPM is the promotion of sustainable bioenergy and the development of alternative energy crops and their applications. Members of GA-UPM have a wide background in biomass teaching and training and their facilities are well-suited to experimental activities pertaining to energy crops, biomass production and biomass conversion technologies.

The course in Bioenergy aims at teaching of technical knowledge and at training in all issues related to biomass as a renewable energy source. In the current academic year (2011-12) the course was scheduled for the period comprised between January 16 and March 1. Fundamentals of bioenergy, state-of-the-art regarding energy crops, agro-energy industries, liquid and solid biofuels, bio-electricity, sustainability and rural development are the main subjects of the course in Bioenergy and according to the structure of the course, the section on liquid biofuels is given in week 5. Lectures on liquid biofuels deal with the current state and prospects of first and second generation biofuels, production of feedstocks, conversion technologies, applications of biofuels and by-products and R+D+i issues.  

Special attention is paid within the course in Bioenergy to alternative feedstocks of liquid biofuels, like sweet sorghum. On this subject, a number of topics have been addressed in the lectures given during the current academic year. Main topics have been the state-of-the-art on sweet sorghum, crop requirements, varieties, crop cycle, cultivation techniques, yields in biomass and sugars, interactions, conversion technologies, R+D+i activities and web resources. In this respect, information generated by EU-funded projects on sorghum has been discussed and also the Sweethanol-online community web site has been presented.

The number of issues dealt with and the active participation of the students have contributed to the dissemination of the knowledge of sweet sorghum as well as to the success of the course in Bioenergy of Master TAPAS.

“They will use sweet sorghum as a complementary crop when they start operating by May,” said Dr. William D. Dar, International Crops Research Institute for the Semi Arid tropics (Icrisat) said during the Philippine International Bioenergy Conference over the weekend.

GFII is a joint venture between Itochu Corp of Japan, JGC Corp.-Japan, Philippine Bioethanol and Energy Investment Corp. and Taiwanese holding firm GCO. The Isabela plant has a production capapcity of 200,000 liters of bioethanol per day or 54 million liters per year. This is close to the combined capacity of the two bioethanol operating plants San Carlos Bioenergy and Roxol Bioenergy with a total of 68 million liters per year.

The new ethanol plants have sustained their interest in sweet sorghum as cost-effective complementary feedstock to sugarcane or molasses as economic feasibility showed a profitable growing of the feedstock.

Sweet sorghum can generate a net income of P83,962 for two croppings in a year at a cane yield of 50 metric tons (MT) per hectare and seed (grain) yield of three MT per hectare, a University of the Philippines-Los Banos-Bureau of Agricultural Research (BAR) study showed. The Philippines has to keep with developments in sweet sorghum growing worldwide as ethanol leader Brazil is already embracing it.

“Private companies in Brazil are partnering with us in doing research on sweet sorghum. (They’re a leader in sugarcane ethanol), that’s why they’re tapping sweet sorghum as a visibility advantage,” Dar said. The potential is “the big sugarcane” area in Brazil.

US multinational Du Pont’s seed company Pioneer and Advanta, an Indian global seed company, have started working with Icrisat on sweet sorghum. Philippines had the lead in getting the support of ICRISAT over the last five years. Icrisat is an international organizations funded by a network of private-public groups supporting the Consultative Group for International Agricultural Research (CGIAR). It has been extending its technical assistance to the Philippines through its superior varieties and support for field trials initiated by BAR since 2006. “It costs us $500,000 dollars to develop a line. If we gave 1,000 varieties to the Philippines, it means we’ve given half a billion dollar. Of course, Icrisat is investing not only for the Philippines but for other developing countries in the world,” Dar said.

SOURCE: http://mb.com.ph/articles/348211/ethanol-plant-uses-sweet-sorghum