Rice Straw As Bioenergy Resource

The cultivation of rice results in two types of biomass residues – straw and husk – having attractive potential in terms of energy. Rice husk, the main by-product from rice milling, accounts for roughly 22% of paddy weight, while rice straw to paddy ratio ranges from 1.0 to 4.3. Although the technology for rice husk utilization is well-established worldwide, rice straw is sparingly used as a source of renewable energy. One of the main reasons for the preferred use of husk is its easy procurement. In case of rice straw, however, its collection is difficult and its availability is limited to harvest time.

Rice_straw

Rice straw can either be used alone or mixed with other biomass materials in direct combustion, whereby combustion boilers are used in combination with steam turbines to produce electricity and heat. The energy content of rice straw is around 14 MJ per kg at 10 percent moisture content.  The by-products are fly ash and bottom ash, which have an economic value and could be used in cement and/or brick manufacturing, construction of roads and embankments, etc.

Straw fuels have proved to be extremely difficult to burn in most combustion furnaces, especially those designed for power generation. The primary issue concerning the use of rice straw and other herbaceous biomass for power generation is fouling, slagging, and corrosion of the boiler due to alkaline and chlorine components in the ash. Europe, and in particular, Denmark, currently has the greatest experience with straw-fired power and CHP plants.

Because of the large amount of cereal grains (wheat and oats) grown in Denmark, the surplus straw plays a large role in the country’s renewable energy strategy. Technology developed includes combustion furnaces, boilers, and superheat concepts purportedly capable of operating with high alkali fuels and having handling systems which minimize fuel preparation.

A variety of methods are employed by the European plants to prepare straw for combustion. Most use automated truck unloading bridge cranes that clamp up to 12 bales at a time and stack them 4-5 bales high in covered storage. Some systems feed whole bales into the boiler. Probably the best known whole bale feeder is the “Vølund cigar feeding” concept, originally applied by Vølund (now Babcock and Wilcox-Vølund). Whole bales are pushed into the combustion chamber and the straw burned off the face of the bale.

However, the newer Danish plants have moved away from whole-bale systems to shredded straw feed for higher efficiency. For pulverized coal co-firing, the straw usually needs to be ground or cut to small sizes in order to burn completely within relatively short residence times (suspension fired systems) or to feed and mix upon injection with bed media in fluidized bed systems.

The chemical composition of feedstock has a major influence on the efficiency of biomass cogeneration. The low feedstock quality of rice straw is primarily determined by high ash content (10–17%) as compared with wheat straw (around 3%) and also high silica content in ash. On the other hand, rice straw as feedstock has the advantage of having a relatively low total alkali content, whereas wheat straw can typically have more than 25% alkali content in ash.

However, straw quality varies substantially within seasons as well as within regions. If straw is exposed to precipitation in the field, alkali and alkaline compounds are leached, improving the feedstock quality. In turn, moisture content should be less than 10% for combustion technology.

In straw combustion at high temperatures, potassium is transformed and combines with other alkali earth materials such as calcium. This in turn reacts with silicates, leading to the formation of tightly sintered structures on the grates and at the furnace wall. Alkali earths are also important in the formation of slag and deposits. This means that fuels with lower alkali content are less problematic when fired in a boiler.

Rationale for Biomass Supply Chain

Biomass resources have been in use for a variety of purposes since ages. The multiple uses of biomass includes usage as a livestock or for meeting domestic and industrial thermal requirements or for the generation of power to fulfill any electrical or mechanical needs. One of the major issues, however, associated with the use of any biomass resources is its supply chain management.

The resource being bulky, voluminous and only seasonally available creates serious hurdles in the reliable supply of the feedstock, regardless of its application. The idea is thus to have something which plugs in this gap between the biomass resource availability and its demand.

The Problem

The supply chain management in any biomass-based project is nothing less than a big management conundrum. The complexity deepens owing to the large number of stages which encompass the entire biomass value chain. It starts right from the resource harvesting and goes on to include the resource collection, processing, storage and eventually its transportation to the point of ultimate utilization.

Owing to the voluminous nature of the resource, its handling becomes a major issue since it requires bigger modes of logistics, employment of a larger number of work-force and a better storage infrastructure, as compared to any other fuel or feedstock. Not only this their lower energy density characteristic, makes it inevitable for the resource to be first processed and then utilized for power generation to make for better economics.

All these hassles associated with such resources, magnify the issue of their utilization when it comes to their supply chain. The seasonal availability of most of the biomass resources, alternative application options, weather considerations, geographical conditions and numerous other parameters make it difficult for the resource to be made consistently available throughout the year. This results in poor feedstock inputs at the utilization point which ends up generating energy in a highly erratic and unreliable manner.

The Solution

Although most of the problems discussed above, are issues inherently associated with the usage of biomass resources, they can be curtailed to a larger extent by strengthening the most important loophole in such projects – The Biomass Resource Supply Chain.

World over, major emphasis has been laid in researching upon the means to improve the efficiencies of such technologies. However, no significant due diligence has been carried out in fortifying the entire resource chain to assure such plants for a continuous resource supply.

The usual solution to encounter such a problem is to have long term contracts with the resource providers to not only have an assured supply but also guard the project against unrealistic escalations in the fuel costs. Although, this solution has been found to be viable, it becomes difficult to sustain such contracts for longer duration since these resources are also susceptible to numerous externalities which could be in the form of any natural disaster, infection from pests or any other socio-political or geographical disturbances, which eventually lead to an increased burden on the producers.

PKS From Africa Can Fuel Biomass Power Plants in Japan

Japan’s biomass fuel requirement is estimated to be tens of millions of tons each year on account of its projected biomass energy capacity of 6,000MW by the year 2030. To achieve this capacity, more than 20 million tons of biomass fuel will be needed every year which will be mainly met by wood pellets and palm kernel shell (PKS). The similarity of the properties of wood pellets with PKS makes PKS the main competitor of wood pellets in the international biomass fuel market.

PKS-biomass

PKS has emerged as an attractive biomass commodity in Japan

Canada and USA are the biggest suppliers of wood pellets to the Japanese biomass market while PKS mainly comes from Indonesia and Malaysia. With the size of the material almost the same as wood pellets, but at a cheaper price (almost half the wood pellets) and also available in abundance, PKS is the preferred biomass fuel for the Japanese market. PKS can be used 100% in power plants that use fluidized bed combustion technology, while wood pellets are used in pulverized combustion.

Although there is abundant PKS in CPO (crude palm oil) producing countries, but fluctuations in CPO production and increase in domestic demand has led to reduction in PKS exports in Southeast Asia. In palm oil plantations, it is known as the low crop season and peak crop season. When the low crop season usually occurs in the summer or dry season, the supply of fruit to the palm oil mills decreases so that the CPO production decreases and also the supply of PKS automatically reduces, and vice versa in the peak crop season. When demand is high or even stable but supply decreases, the price of PKS tends to rise.

In addition, a wide range of industries in Indonesia and Malaysia have also began to use PKS as an alternative fuel triggering increased domestic demand. In recent years, PKS is also being processed into solid biomass commodities such as torrified PKS, PKS charcoal and PKS activated carbon. Thus, there is very limited scope of increasing PKS supply from Southeast Asia to large-scale biomass consumers like Japan and South Korea.

Palm oil mills process palm oil fruit from palm oil plantations, so the more fruit is processed the greater the PKS produced and also more processors or mills are needed. At present it is estimated that there are more than 1500 palm oil mills in Indonesia and Malaysia. Palm kernel shells from Indonesia and Malaysia is either being exported or used domestically by various industries. On the other hand, in other parts of the world PKS is still considered a waste which tends to pollute the environment and has no economic value.

Palm Oil Producers

Top palm oil producers around the world

West African countries, such Nigeria, Ghana and Togo, are still struggling to find a sustainable business model for utilization of PKS. Keeping in view the tremendous PKS requirements in the Asia-Pacific region, major PKS producers in Africa have an attractive business opportunity to export this much-sought after biomass commodity to the Japan, South Korea and even Europe.

Simply speaking, PKS collected from palm oil mills is dried, cleaned and shipped to the destination country. PKS users have special specifications related to the quality of the biomass fuel used, so PKS needs to be processed before exporting.

PKS-export

PKS exports from Indonesia and Malaysia to Japan are usually  with volume 10 thousand tons / shipment by bulk ship. The greater the volume of the ship or the more cargo the PKS are exported, the transportation costs will generally be cheaper. African countries are located quite far from the Asia-Pacific region may use larger vessels such as the Panamax vessel to export their PKS.

Agricultural Wastes in the Middle East

Agriculture plays an important role in the economies of most of the countries in the Middle East.  The contribution of the agricultural sector to the overall economy varies significantly among countries in the region, ranging, for example, from about 3.2 percent in Saudi Arabia to 13.4 percent in Egypt.  Large scale irrigation is expanding, enabling intensive production of high value cash and export crops, including fruits, vegetables, cereals, and sugar.

The term ‘crop residues’ covers the whole range of biomass produced as by-products from growing and processing crops. Crop residues encompasses all agricultural wastes such as bagasse, straw, stem, stalk, leaves, husk, shell, peel, pulp, stubble, etc. Wheat and barley are the major staple crops grown in the Middle East region. In addition, significant quantities of rice, maize, lentils, chickpeas, vegetables and fruits are produced throughout the region, mainly in Egypt, Syria, Saudi Arabia and Jordan.

Agricultural Wastes in the Middle East

Large quantities of agricultural wastes are produced annually in the Middle East, and are vastly underutilised. Current farming practice in the Middle East is usually to plough these residues back into the soil, or they are burnt, left to decompose, or grazed by cattle. These residues could be processed into liquid fuels, solid fuels or thermochemically processed to produce electricity and domestic heat in rural areas.

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Date palm biomass is an excellent resource for charcoal production in Middle East

Date palm is one of the principal agricultural products in the arid and semi-arid region of the world, especially Middle East and North Africa (MENA) region. The Arab world has more than 84 million date palm trees with the majority in Egypt, Iraq, Saudi Arabia, Iran, Algeria, Morocco, Tunisia and United Arab Emirates.

Date palm trees produce huge amount of agricultural wastes in the form of dry leaves, stems, pits, seeds etc. A typical date tree can generate as much as 20 kilograms of dry leaves per annum while date pits account for almost 10 percent of date fruits. Some studies have reported that Saudi Arabia alone generates more than 200,000 tons of date palm biomass each year.

In Egypt, crop residues are considered to be the most important and traditional source of domestic fuel in rural areas. These crop residues are by-products of common crops such as cotton, wheat, maize and rice. The total amount of residues reaches about 16 million tons of dry matter per year.

Cotton residues represent about 9% of the total amount of residues. These are materials comprising mainly cotton stalks, which present a disposal problem. The area of cotton crop cultivation accounts for about 5% of the cultivated area in Egypt.

A cotton field in Egypt

Energy crops, such as Jatropha, can be successfully grown in arid regions for biodiesel production. Infact, Jatropha is already grown at limited scale in some Middle East countries and tremendous potential exists for its commercial exploitation.

Date Palm as Biomass Resource

Date palm is one of the principal agricultural products in the arid and semi-arid region of the world, especially Middle East and North Africa (MENA) region. There are more than 120 million date palm trees worldwide yielding several million tons of dates per year, apart from secondary products including palm midribs, leaves, stems, fronds and coir. The Arab world has more than 84 million date palm trees with the majority in Egypt, Iraq, Saudi Arabia, Iran, Algeria, Morocco, Tunisia and United Arab Emirates.

date-wastes

Date palm biomass is found in large quantities across the Middle East

Egypt is the world’s largest date producer with annual production of 1.47 million tons of dates in 2012 which accounted for almost one-fifth of global production. Saudi Arabia has more than 23 millions date palm trees, which produce about 1 million tons of dates per year.

Biomass Potential of Date Palm

Date palm trees produce huge amount of agricultural wastes in the form of dry leaves, stems, pits, seeds etc. A typical date tree can generate as much as 20 kilograms of dry leaves per annum while date pits account for almost 10 percent of date fruits. Some studies have reported that Saudi Arabia alone generates more than 200,000 tons of date palm biomass each year.

Date palm is considered a renewable natural resource because it can be replaced in a relatively short period of time. It takes 4 to 8 years for date palms to bear fruit after planting, and 7 to 10 years to produce viable yields for commercial harvest. Usually date palm wastes are burned in farms or disposed in landfills which cause environmental pollution in dates-producing nations. In countries like Iraq and Egypt, a small portion of palm biomass in used in making animal feed.

The major constituents of date palm biomass are cellulose, hemicelluloses and lignin. In addition, date palm has high volatile solids content and low moisture content. These factors make date biomass an excellent waste-to-energy resource in the MENA region.

Technology Options for Date Palm Biomass Utilization

A wide range of thermal and biochemical technologies exists to tap the energy stored in date palm biomass to useful forms of energy. The low moisture content in date palm wastes makes it well-suited to thermochemical conversion technologies like combustion, gasification and pyrolysis which may yield steam, syngas, bio oil etc.

On the other hand, the high volatile solids content in date palm biomass indicates its potential towards biogas production in anaerobic digestion plants, possibly by codigestion with sewage sludge, animal wastes and/and food wastes. The cellulosic content in date palm wastes can be transformed into biofuel (bioethanol) by making use of the fermentation process.

The highly organic nature of date palm waste makes it highly suitable for compost production which can be used to replace chemical fertilizers in date palm plantations. Thus, abundance of date palm trees in the MENA and the Mediterranean region, can catalyze the development of biomass and biofuels sector in the region.

An Introduction to Biomass Harvesting

Biomass harvesting and collection is an important step involving gathering and removal of the biomass from field which is dependent on the state of biomass, i.e. grass, woody, or crop residue. The moisture content and the end use of biomass also affect the way biomass is collected. For crop residues, the operations should be organized in sync with the grain harvest as it occupies the centrestage in farming process.

biomass-harvesting

All of other operations such as residue management and collection take place after so-called grain is in the bin. On the other hand, the harvest and collection dedicated crops (grass and woody) can be staged for recovery of the biomass only. In agricultural processing, straw is the stems and leaves of small cereals while chaff is husks and glumes of seed removed during threshing.

Modern combine-harvesters generally deliver straw and chaff together; other threshing equipment separates them. Stover is the field residues of large cereals, such as maize and sorghum. Stubble is the stumps of the reaped crop, left in the field after harvest. Agro-industrial wastes are by-products of the primary processing of crops, including bran, milling offal, press-cakes and molasses. Bran from on-farm husking of cereals and pulses are fed to livestock or foraged directly by backyard fowls.

The proportion of straw, or stover, to grain varies from crop to crop and according to yield level (very low grain yields have a higher proportion of straw) but is usually slightly over half the harvestable biomass. The height of cutting will also affect how much stubble is left in the field: many combine-harvested crops are cut high; crops on small-scale farms where straw is scarce may be cut at ground level by sickle or uprooted by hand.

Modern combine-harvesters generally deliver straw and chaff together

Collection involves operations pertaining to gathering, packaging, and transporting biomass to a nearby site for temporary storage. The amount of a biomass resource that can be collected at a given time depends on a variety of factors. In case of agricultural residues, these considerations include the type and sequence of collection operations, the efficiency of collection equipment, tillage and crop management practices, and environmental restrictions, such as the need to control erosion, maintain soil productivity, and maintain soil carbon levels.

Biogas Sector in India: Perspectives

Biogas is an often overlooked and neglected aspect of renewable energy in India. While solar, wind and hydropower dominate the discussion in the cuntry, they are not the only options available. Biogas is a lesser known but highly important option to foster sustainable development in agriculture-based economies, such as India.

What is Biogas

Briefly speaking, biogas is the production of gaseous fuel, usually methane, by fermentation of organic material. It is an anaerobic process or one that takes place in the absence of oxygen. Technically, the yeast that causes your bread to rise or the alcohol in beer to ferment is a form of biogas. We don’t use it in the same way that we would use other renewable sources, but the idea is similar. Biogas can be used for cooking, lighting, heating, power generation and much more. Infact, biogas is an excellent and effective to promote development of rural and marginalized communities in all developing countries.

This presents a problem, however. The organic matter is putting off a gas, and to use it, we have to turn it into a liquid. This requires work, machinery and manpower. Research is still being done to figure out the most efficient methods to make it work, but there is a great deal of progress that has been made, and the technology is no longer new.

Fossil Fuel Importation

India has a rapidly expanding economy and the population to fit. This has created problems with electricity supplies to expanding areas. Like most countries, India mainly uses fossil fuels. However, as oil prices fluctuate and the country’s demand for oil grows, the supply doesn’t always keep up with the demand. In the past, India has primarily imported oil from the Middle East, specifically Saudi Arabia and Iraq.

Without a steady and sustainable fossil fuels supply, India has looking more seriously into renewable sources they can produce within the country. Biogas is an excellent candidate to meet those requirements and has been used for this goal before.

Biogas in India

There are significant differences between biogas and fossil fuels, but for India, one of the biggest is that you can create biogas at home. It’s pretty tricky to find, dig up and transform crude oil into gas, but biogas doesn’t have the same barriers. In fact, many farmers who those who have gardens or greenhouses could benefit with proper water management and temperature control so that plants can be grown year round, It still takes some learning and investment, but for many people, especially those who live in rural places, it’s doable.

This would be the most beneficial to people in India because it would help ease the strain of delivering reliable energy sources based on fossil fuels, and would allow the country to become more energy independent. Plus, the rural areas are places where the raw materials for biogas will be more available, such animal manure, crop residues and poultry litter. But this isn’t the first time most people there are hearing about it.

Biogas in India has been around for a long time. In the 1970’s the country began a program called the National Biogas and Manure Management Program (NBMMP) to deal with the same problem — a gas shortage. The country did a great deal of research and implemented a wide variety of ideas to help their people become more self-sufficient, regardless of the availability of traditional gasoline and other fossil fuel based products.

The original program was pioneering for its time, but the Chinese quickly followed suit and have been able to top the market in biogas production in relatively little time. Comparatively, India’s production of biogas is quite small. It only produces about 2.07 billion m3/year of biogas, while it’s estimated that it could produce as much as 48 billion m3/year. This means that there are various issues with the current method’s India is using in its biogas production.

Biogas_Animal

Biogas has the potential to rejuvenate India’s agricultural sector

The original planning in the NBMMP involved scientists who tried to create the most efficient biogas generators. This was good, but it slowed people’s abilities to adopt the techniques individually. China, on the other hand, explicitly worked to help their most rural areas create biogas. This allowed the country to spread the development of biogas to the most people with the lowest barriers to its proliferation.

If India can learn from the strategy that China has employed, they may be able to give their biogas production a significant boost which will also help in the rejuvenation of biomass sector in the country. Doing so will require the help and willingness of both the people and the government. Either way, this is an industry with a lot of room for growth.

Thermal Conversion of Biomass

A wide range of thermal technologies exists to harness the energy stored in biomass. These technologies can be classified according to the principal energy carrier produced in the conversion process. Carriers are in the form of heat, gas, liquid and/or solid products, depending on the extent to which oxygen is admitted to the conversion process (usually as air). The major methods for thermal conversion of biomass are combustion, gasification and pyrolysis.

biomass-gasification

Combustion

Conventional combustion technologies raise steam through the combustion of biomass. This steam may then be expanded through a conventional turbo-alternator to produce electricity. A number of combustion technology variants have been developed. Underfeed stokers are suitable for small scale boilers up to 6 MWth.

Grate type boilers are widely deployed. They have relatively low investment costs, low operating costs and good operation at partial loads. However, they can have higher NOx emissions and decreased efficiencies due to the requirement of excess air, and they have lower efficiencies.

Fluidized bed combustors (FBC), which use a bed of hot inert material such as sand, are a more recent development. Bubbling FBCs are generally used at 10-30 MWth capacity, while Circulating FBCs are more applicable at larger scales. Advantages of FBCs are that they can tolerate a wider range of poor quality fuel, while emitting lower NOx levels.

Co-Firing

Co-firing or co-combustion of biomass wastes with coal and other fossil fuels can provide a short-term, low-risk, low-cost option for producing renewable energy while simultaneously reducing the use of fossil fuels. Co-firing involves utilizing existing power generating plants that are fired with fossil fuel (generally coal), and displacing a small proportion of the fossil fuel with renewable biomass fuels.

types-of-biomass-cofiring

Co-firing has the major advantage of avoiding the construction of new, dedicated, waste-to-energy power plant. Co-firing may be implemented using different types and percentages of wastes in a range of combustion and gasification technologies. Most forms of biomass wastes are suitable for co-firing. These include dedicated municipal solid wastes, wood waste and agricultural residues such as straw and husk.

Gasification

Gasification of biomass takes place in a restricted supply of oxygen and occurs through initial devolatilization of the biomass, combustion of the volatile material and char, and further reduction to produce a fuel gas rich in carbon monoxide and hydrogen. This combustible gas has a lower calorific value than natural gas but can still be used as fuel for boilers, for engines, and potentially for combustion turbines after cleaning the gas stream of tars and particulates.

Biomass_Gasification_Process

Layout of a Typical Biomass Gasification Plant

If gasifiers are ‘air blown’, atmospheric nitrogen dilutes the fuel gas to a level of 10-14 percent that of the calorific value of natural gas. Oxygen and steam blown gasifiers produce a gas with a somewhat higher calorific value. Pressurized gasifiers are under development to reduce the physical size of major equipment items.

A variety of gasification reactors have been developed over several decades. These include the smaller scale fixed bed updraft, downdraft and cross flow gasifiers, as well as fluidized bed gasifiers for larger applications. At the small scale, downdraft gasifiers are noted for their relatively low tar production, but are not suitable for fuels with low ash melting point (such as straw). They also require fuel moisture levels to be controlled within narrow levels.

Pyrolysis

Pyrolysis is the term given to the thermal degradation of wood in the absence of oxygen. It enables biomass to be converted to a combination of solid char, gas and a liquid bio-oil. Pyrolysis technologies are generally categorized as “fast” or “slow” according to the time taken for processing the feed into pyrolysis products. These products are generated in roughly equal proportions with slow pyrolysis. Using fast pyrolysis, bio-oil yield can be as high as 80 percent of the product on a dry fuel basis.

Biomass-Pyrolysis

Bio-oil can act as a liquid fuel or as a feedstock for chemical production. A range of bio-oil production processes are under development, including fluid bed reactors, ablative pyrolysis, entrained flow reactors, rotating cone reactors, and vacuum pyrolysis.

Energy from Biomass Wastes in MENA

The high volatility in oil prices in the recent past and the resulting turbulence in energy markets has compelled many MENA countries, especially the non-oil producers, to look for alternate sources of energy, for both economic and environmental reasons. The significance of renewable energy has been increasing rapidly worldwide due to its potential to mitigate climate change, to foster sustainable development in poor communities, and augment energy security and supply.

The MENA region is well-poised for biomass waste-to-energy development, with its rich feedstock base in the form of municipal solid wastes, crop residues and agro-industrial wastes. The high rate of population growth, urbanization and economic expansion in the Middle East is not only accelerating consumption rates but also accelerating the generation of a wide variety of waste.

Bahrain, Saudi Arabia, UAE, Qatar and Kuwait rank in the top-ten worldwide in terms of per capita waste generation. The gross urban waste generation quantity from Arab countries is estimated at more than 80 million tons annually. Open dumping is the most prevalent mode of municipal solid waste disposal in most countries.

rubbish-salmiya-kuwait

Many Middle East nations lack legislative framework and regulations to deal with urban wastes.

Biomass wastes-to-energy technologies hold the potential to create renewable energy from biomass waste in the MENA region. Besides recovery of substantial energy, these technologies can lead to a substantial reduction in the overall waste quantities requiring final disposal, which can be better managed for safe disposal in a controlled manner. Energy from biomass wastes can contribute substantially to GHG mitigation in the Middle East through both reductions of fossil carbon emissions and long-term storage of carbon in biomass wastes.

Biomass waste-to-energy systems options offer significant, cost-effective and perpetual opportunities for greenhouse gas emission reductions. Additional benefits offered are employment creation in rural areas, reduction of a country’s dependency on imported energy carriers (and the related improvement of the balance of trade), better waste control, and potentially benign effects with regard to biodiversity, desertification, recreational value, etc.

In summary, waste-to-energy can significantly contribute to sustainable development both in developed and less developed countries. Waste-to-energy is not only a solution to reduce the volume of waste that is and provide a supplemental energy source, but also yields a number of social benefits that cannot easily be quantified.

Biomass wastes in MENA can be efficiently converted into energy and fuels by biochemical and thermal conversion technologies, such as anaerobic digestion, gasification and pyrolysis. Waste-to-energy technologies hold the potential to create renewable energy from waste matter.

The implementation of waste-to-energy technologies as a method for safe disposal of solid and liquid biomass wastes, and as an attractive option to generate heat, power and fuels, can significantly reduce environmental impacts of wastes in the MENA region. In fact, energy recovery from MSW is rapidly gaining worldwide recognition as the fourth ‘R’ in sustainable waste management system – Reuse, Reduce, Recycle and Recover.

A transition from conventional waste management system to one based on sustainable practices is necessary to address environmental concerns and to foster sustainable development in the region.

Sugarcane Trash – A Wonderful Resource that Indian Sugar Industry is Wasting

In Indian sugar mills, the frequent cycles of ups and downs in the core business of selling sugar has led to the concentration towards the trend of ancillary businesses, like cogeneration power plant and ethanol production, becoming the profit centres. These units, which were introduced as a means to manage sugar mills’ own byproduct, like bagasse, are now keeping several sugar mills financially afloat. Thus, the concept of ‘Integrated Sugar Mill Complex’ has now become a new normal.

Limitations of Bagasse

Bagasse is a ubiquitous primary fuel in cogeneration plants in sugar mills, which adds more than 2,000 MW of renewable power to the Indian energy mix. The inclination of cogeneration plant managers towards bagasse is primarily because of its virtue of being easily available on-site, and no requirement to purchase it from the external market.

This remains true despite its several significant shortcomings as a boiler fuel, prime among which are very high moisture content and low calorific value. As a result, the fuel-to-energy ratio remains abysmally low and the consequent lesser power generation is depriving these sugar mills from achieving true revenue potential from their ancillary power business vertical, which is pegged at ~10,000 MW.

Sugarcane Trash – A Wonder Waste

Though, there is a much neglected high calorific value biomass which is available in proximity of every sugar mill and is also a residue of the sugarcane crop itself, which could enable the cogeneration units to achieve their maximum output potential. This wonder waste is sugarcane trash the dry leaves of sugarcane crop – which is left in the farms itself after sugarcane harvesting as it has no utility as fodder and generally burnt by farmers, which harms the surrounding air quality substantially.

Given its favourable properties of having very low moisture content with moderate-to-high calorific value, sugarcane trash could be used in most of the high pressure boiler designs in a considerable proportion along with bagasse.

cane-trash

Undeniably, sugar mills should not discontinue using bagasse as the primary fuel, but surely complement it with sugarcane trash as it would lead to an increase in their revenue generation and would also allow them to expand operations of their cogeneration plant to off-season, as using sugarcane trash with bagasse in season would leave more bagasse for off season usage.

Hurdles to Overcome

Despite these evident benefits, the major obstacle in development of sugarcane trash as an industrial boiler fuel has been its difficult collection from thousands of small and fragmented farms. Moreover, the trash becomes available and needs to be collected simultaneously during the operating season of the sugar mills, which makes deployment of resources, human or otherwise, for managing the procurement of trash very difficult for any sugar mill.

As a matter of fact, the sugar mills which initiated the pilots, or even scaled commercially, to utilise sugarcane trash along with bagasse, had to sooner or later discontinue its use, owing to the mammoth challenges discussed above.

The Way Forward

Thus, in order to utilise this wonder waste, there is a dire need to outsource its procurement to professional and organised players, like RY Energies and others, which establish the biomass supply chain infrastructure in the vicinity of the cogeneration units to make on-site availability of sugarcane trash as convenient as bagasse and enable them to procure the rich quality biomass at sustainable prices which leads to an increase in their profits.

sugarcane-trash-burning

Burning of cane trash creates pollution in sugar-producing countries

These biomass supply chain companies offer value to the farmers by processing their crop residues in timely manner, thus prevent open burning of the crop residue and contribute to a greener and cleaner environment.

Indeed, owing to its favourable fuel properties, positive environmental impact and now, with ease in its procurement, sugarcane trash biomass is the fuel of today and future for the Indian sugar mills.