The idea of biogas is anything but new. People have been experimenting with making biogas for many generations. Biogas is made by converting organic waste into energy. It’s a huge win for the environment because it utilizes what is otherwise considered waste, but it’s a big win for pocketbooks too.
Organic waste includes the byproducts of human food production (think potato peels, carrot peels, the tops of turnips, etc) but it also includes manure. Any manure is fair game, think about cows, pigs, chickens, rabbits, goats — virtually any farm animal produces mounds of this each day.
This manure produces very high levels of methane gas which is horrible for the environment. By using this manure to create biogas, we remove the danger of creating heat-trapping gases in our atmosphere that raises the temperature of the entire planet. Using it for biogas production can also help to reduce global warming.
How Do We Produce Biogas?
Biogas is produced from the breakdown of organic waste in an environment that is void of oxygen. We call this environment anaerobic and the process is process is called anaerobic digestion. Two products are created from this process. One is digestate. Digestate can be used for fertilizer and even as livestock bedding. The other product is biogas. Biogas can be used for heating, electricity production and as a clean vehicle fuel.
It’s essentially like composting all of the materials, but in an environment without oxygen and in the temperature range of around 35 to 40 degrees Celsius and pH of around 7. This is optimal to produce biogas. Biogas can be converted into an upgraded form of gas by removal of carbon dioxide that can be used like natural gas. It can be used as-is as an engine fuel. It can be used as fuel in a vehicle, sometimes without modification.
How Can You Produce Your Own Biogas?
Just imagine being on your own off-grid property, running a hundred head of cattle, growing your own food and canning it. You’ve got meat covered, your food is stocked and you are prepared for just about anything. But what about fuel? Imagine what a game-changer it could be if you were able to produce your own fuel from the waste from your cattle and your garden scraps or food residuals! You can!
The Biogas Digester makes it possible, and fairly easy, for you to start producing your own biogas. Buy a ready-made biodigester for around $700-$1000 dollars and start producing your own biogas to meet your fuel requirements. They are containers designed to do the work for you and help you collect the fruits of your composted and digested waste.
Build your own! China has approximately 30 million Biodigesters in use in its rural areas. Rural Chinese areas are far removed from cities that have gas stations. It simply isn’t accessible as it is in the US. Many rural people have learned to make their own biodigesters to fill their fuel needs.
You need a tank that is sealed with an access hole on one side for adding organic waste. You have another access to an outlet. That is where you collect the liquid run-off that can be used for fuel.
The bottom of the main unit is the digestion chamber. From that is an outlet where the digestate can be collected and used as fertilizer. The main chamber typically has a domed top to allow for the room that will be necessary for the expansion of the gases formed inside. By being sealed, the unit creates that all-important anaerobic environment.
Useful Links
A tank that demonstrates the size and simplicity of a tank that can be purchased and used in the backyard.
Sweden is considered as a global leader in sustainable waste management and in the reduction of per capita carbon footprint. The country consistently works to lower its greenhouse gas emissions, improve energy efficiency and increase public awareness. Over the past 10 years, Sweden developed methods of repurposing waste, so less than one percent of the total waste generated in the country makes it to landfills. To accomplish this, the country changed their perspective of garbage.
Increase Recycling
Recycling is a part of Swedish culture. Residents regularly sort recyclable materials and food scraps from other waste in their homes before disposal. This streamlines the recycling process and reduces the effort required to sort large volumes of waste at larger recycling centers. As another way to promote recycling, the Swedish government created legislation stating recycling centers must be within 1,000 feet of residential areas. Conveniently located facilities encourage citizens to properly dispose of their waste.
Repurpose Materials
Citizens are also encouraged to reuse or repurpose materials before recycling or disposing of them. Repurposing and reusing products requires less energy when compared to the recycling or waste disposal process. As Swedes use more repurposed products, they reduce the volume of new products they consume which are created from fresh materials. In turn, the country preserves more of its resources.
Invest in Waste to Energy
Over 50 percent of the waste generated in Sweden is burned in waste-to-energy facilities. The energy produced by these facilities heats homes across the country during the long winter months. Localized heating — known as district heating — has improved air quality throughout the nation. It’s easier and more economical to control the emissions from several locations as opposed to multiple, smaller non-point sources.
Another benefit of waste-to-energy facilities is that ash and other byproducts of the burning process can be used for road construction materials. As a whole, Sweden doesn’t create enough waste to fuel its waste to energy plants — the country imports waste from its neighbors to keep its facilities going.
In the early 1990’s, the Swedish government shifted the responsibility for waste management from cities to the industries producing materials which would eventually turn to waste. To promote burning waste for energy, the government provides tax incentives to companies which make more economically attractive.
Impact of Waste-to-Energy
Although Sweden has eliminated the volume of trash entering landfills, they have increased their environmental impacts in other ways. Waste-to-energy facilities are relatively clean in that most harmful byproducts are filtered out before entering the environment, though they still release carbon-dioxide and water as their primary outputs. On average, waste-to-energy plants generate nearly 20 percent more carbon-dioxide when compared to coal plants.
Coal plants burn and release carbon which is otherwise sequestered in the ground and unable to react with the earth’s atmosphere. Waste-to-energy facilities consume and release carbon from products made of organic materials, which naturally release their carbon over time. The downside to this process is that it frees the carbon from these materials at a much faster rate than it would be naturally.
The reliance on the waste-to-energy process to generate heat and the tax incentives may lower Swedish motivation to recycle and reuse materials. The country already needs to import trash to keep their waste-to-energy plants running regularly. Another disadvantage of this process is the removal and destruction of finite materials from the environment.
Even though Sweden continues to make strides in lowering their environmental impact as a whole, they should reevaluate their reliance on waste to energy facilities.
Biomethane, also known as the green gas, is a well-known and well-proven source of clean energy, and is witnessing increasing demand worldwide, especially in European countries, as it is one of the most cost-effective and eco-friendly replacement for natural gas and diesel.
Advantages of Biomethane
The key advantage of biomethane is that it is less corrosive than biogas which makes it more flexible in its application than raw biogas. It can be injected directly into the existing natural gas grid leading to energy-efficient and cost-effective transport, besides allowing natural gas grid operators to persuade consumers to make a smooth transition to a renewable source of natural gas.
Biogas can be upgraded to biomethane and injected into the natural gas grid to substitute natural gas or can be compressed and fuelled via a pumping station at the place of production. Biomethane can be injected and distributed through the natural gas grid, after it has been compressed to the pipeline pressure.
The injected biomethane can be used at any ratio with natural gas as vehicle fuel. In many EU countries, the access to the gas grid is guaranteed for all biogas suppliers.
A major advantage of using natural gas grid for biomethane distribution is that the grid connects the production site of biomethane, which is usually in rural areas, with more densely populated areas. This enables biogas to reach new customers.
Storage of Biomethane
Biomethane can be converted either into liquefied biomethane (LBM) or compressed biomethane (CBM) in order to facilitate its long-term storage and transportation. LBM can be transported relatively easily and can be dispensed through LNG vehicles or CNG vehicles. Liquid biomethane is transported in the same manner as LNG, that is, via insulated tanker trucks designed for transportation of cryogenic liquids.
Biomethane can be stored as CBM to save space. The gas is stored in steel cylinders such as those typically used for storage of other commercial gases.
Applications of Biomethane
Biomethane can be used to generate electricity and heating from within smaller decentralized, or large centrally-located combined heat and power plants. It can be used by heating systems with a highly efficient fuel value, and employed as a regenerative power source in gas-powered vehicles.
Biomethane, as a transportation fuel, is most suitable for vehicles having engines that are based on natural gas (CNG or LNG). Once biogas is cleaned and upgraded to biomethane, it is virtually the same as natural gas.
Because biomethane has a lower energy density than NG, due to the high CO2 content, in some circumstances, changes to natural gas-based vehicle’s fuel injection system are required to use the biomethane effectively.
The disposal of municipal solid waste is the second most major concern for public health in developing countries because of population explosion, rampant poverty and high urbanization rates combined with poor government funding to curb waste management. Factors such as waste composition, technologies and lack of infrastructure have been found to set apart the good management of solid wastes in developing nations. Municipal waste is mainly comprised of paper, vegetable matter, plastics, metals, textiles, rubber and glass. In some countries (developing as well as developed), municipal solid waste is mixed with medical wastes and this may pose health risk to waste handlers and general public.
Historically, burying the wastes is the most preferred method for waste management in many countries. This method is still used in many more countries. Tackling environmental issues has become more important and more preferred than pollution and consumption of unsustainable utilization of resources. Most importantly, the primary objective of waste management is to put emphasis on protecting the people and environment from potentially harmful effects of waste.
Methods of Solid Waste Management
Depending on the types of wastes generated, four methods of solid waste management has been used throughout the history, i.e. dumping, incineration, recycling and waste prevention. Waste generated from household is much different from industrial waste, agricultural waste, medical waste or mining wastes.
When wastes contain any hazardous component, or it has capability to become hazardous with time, poses very serious threat to environment and health. Hazardous wastes generated needs to be handled very carefully, with special techniques. This is one of the major reasons of open landfills are getting replaced with sanitary landfills.
At a landfill, wastes are covered with thick layer of soil. By the late 1950, this practice was very common for waste management across the world. Earlier landfills had considerable sludge and methane emissions, which were harmful to the environment as well as animal and human health. But these issues have been resolved largely by modern disposal methods, which were developed around 20 years ago. Modern landfills are equipped with thick layer of clay followed by plastic sheets. This method was practiced by some nations and still going on.
In 1930-1940, many cities in USA adopted new technology to curb waste issues by burning at high temperature, this method is known as incineration. During initial years, this method was not very efficient and emit very large amount of poisonous gasses, this is the major reason of incinerators shut down during that period. During mid-1970s, scientists modified incinerators to generate energy, which are known as waste to energy plants. But after around a decade, it has become major issue to build these plants, again because of emission issues.
With development of technology, waste burning in advanced form of incinerators became common in 1970s, researchers across the world bet on incinerators or waste to energy plants for solution to energy crisis in 1973. However, with realisation of impact on environment and air quality, it become very difficult to find location to build any waste to energy plants, mainly because of public opposition. Another issue with incinerator is production of ashes, which contain huge amount of heavy metals, toxic and inorganic compounds.
Incineration is the most common waste-to-energy method used worldwide.
Future of Solid Waste Management
The overall concept of wastes needs to be considered economically, it will be more considered as economically viable product if waste is considered as an inefficiency of the production process not as rejected residue of waste product. A permanent rejection or heavy restriction into products which produces waste that cannot be accumulated back into the environment safely.
The major challenge in waste management is to persuade people/community to consider waste as a resource, rather than a liability on society, which can be created with more innovation and technological development of manufacturing industry, waste processing industry and new business model and plans.
This planning system will create circular economy where product value created by inputs (e.g. energy, materials, labour etc.) is extended by enabling a material that goes into circular economy, beyond product life. We go from mineral to metals to product then back to minerals/metals. By understanding economic cycle of waste, people will understand the creation of opportunities to more sustainable product in future with limited resources.
The biggest challenge in the implementation of Waste-to-Energy projects lies not in the technology itself but in the acceptance of citizens. Citizens who are environmentally minded but lack awareness of the current status of MSW-to-energy bring up concerns of environmental justice and organize around this. They view waste-to-energy as ‘dumping’ of pollutants on lower strata of society and their emotional critique rooted in the hope for environmental justice tends to move democracy.
An advocate of public understanding of science, Shawn Lawrence Otto regrets that the facts are not able to hold the same sway. Some US liberal groups such as the Center for American Progress are beginning to realize that the times and science have changed. It will take more consensus on the science and the go ahead from environmental groups before the conversation moves forward, seemingly improbable but not without precedent.
Spittelau Waste-to-Energy Plant
The Spittelau waste-to-energy plant is an example of opposition coming together in consensus over WTE. It was built in Vienna in 1971 with the purpose of addressing district heating and waste management issues. Much later awareness of the risks of dioxins emitted by such plants grew and the people’s faith in the technology was called into question.
It also became a political issue whereby opposition parties challenged the mayor on the suitability of the plant. The economic interests of landfill owners also lay in the shutting down of the WTE facility. The alternative was to retrofit the same plant with advanced technology that would remove the dioxins through Selective Catalytic Reduction (SCR).
Through public discussions it appeared that the majority of the people were against the plant altogether though thorough studies by informed researchers showed that the science backs WTE. The mayor, Helmut Zilk eventually consulted Green Party members on how to make this technology better perceived in the eyes of the people, and asked the famous Austrian artist Freidensreich Hundertwasser, who was a green party member to design the look of the plant.
Freidensreich Hundertwasser after carefully studying the subject wrote a letter of support, stating his belief as to why WTE was needed and accepted Mayor Helmut Zilk’s request. Later public opinion polls showed that there were a majority of people who were either in favor of or not opinionated about the plant, with only 3% in outright opposition of the plant.
Polarized Discussion
Waste-to-Energy or recycling has kept public discourse from questioning whether there may not be intermediate or case specific solutions. This polarization serves to move the conversation nowhere. For now it can be agreed that landfills are devastating in their contribution to Climate Change and must be done away with.
The choice then, of treatment processes for municipal solid waste are plentiful. If after recovery of recyclable materials there remains a sizeable waste stream the option of waste-to-energy can be explored.
Primary Considerations in WTE Projects
Environmental implications (i.e. CO2 emissions vis-à-vis the next best fuel source) given the composition of the local waste stream. If the waste stream consists of a high percentage of recyclables the more sustainable waste strategy would be to ramp up recycling efforts rather than to adopt WTE,
Likely composition and variation of the waste stream and the feasibility of the technology to handle such a waste stream,
Financial considerations with regards to the revenue stream from the WTE facility and its long term viability,
Efforts at making citizens aware of the high standards achieved by this technology in order to secure their approval.
Note: This excerpt is being published with the permission of our collaborative partner Be Waste Wise. The original excerpt and its video recording can be found at this link
Urban waste management has emerged as a big challenge for the government and local bodies in Saudi Arabia. The country generates more than 15 million tons of municipal solid waste each year with per capita waste production estimated to be 2 kg per day, among the highest worldwide. Municipal waste production in three largest cities – Riyadh, Jeddah and Dammam – exceeds 6 million tons per annum which gives an indication of the enormity of the problem faced by civic bodies.
The Problem of Waste
Municipal waste generation in Saudi Arabia is increasing at an unprecedented rate. Due to high population growth rate, rapid urbanization and fast-paced economic development, MSW generation is expected to cross 30 million tons per year by 2033. More than 75 percent of Kingdom’s population is concentrated in urban areas, and collected garbage is thrown in landfills or dumpsites without any processing or treatment.
Most of the landfills in Saudi Arabia are non-sanitary and prone to problems like leachate, vermin, flies and spontaneous fires, apart from greenhouse gas emissions. It has become necessary for the Saudi government to devise an integrated waste management strategy, using international best practices and modern technologies, to tackle heaps of garbage accumulating across the country.
Promise of Waste-to-Energy
Waste-to-energy provides a cost-effective and eco-friendly solution to both energy demand and MSW disposal problems in Saudi Arabia. Increasing waste generation, inability of existing solutions to tackle waste and expansion of cities into ex-dump sites are strong drivers for large-scale deployment of WTE systems in the Kingdom.
Saudi Arabia has tremendous waste-to-energy potential due to plentiful availability of good quality municipal waste. Modern waste-to-energy technologies, such as RDF-based incineration, gasification, pyrolysis and anaerobic digestion have the ability to transform power demand and waste management scenario in the country.
A typical 250 – 300 tons per day garbage-to-energy plant can produce around 3 – 4 MW of electricity and a network of such plants in cities around the country can make a real difference in waste management as well as energy sectors. In fact, such plants also produce tremendous about of heat energy which can be utilized in process industries and district cooling systems, further maximizing their usefulness.
Key Challenges
Around the world, waste-to-energy finds wide acceptance as a tool to manage urban wastes, with more than 1,000 waste-to-energy plants in operation globally, especially in Europe, China and the Asia-Pacific. However, waste-to-energy is struggling to get off-the-ground in Saudi Arabia due to several issues, the main reason being the cheap and plentiful availability of oil which prevents decision-makers to set effective regulations for waste-to-energy development in the country.
Waste-to-Energy is widely accepted as a part of sustainable waste management strategy worldwide.
Policy-makers in KSA should consider waste-to-energy as a sustainable waste management solution, rather than as a power-producing industry. Unlike Western countries, waste management services are practically free-of-cost for the waste generators which act as a deterrent for governmental investment in new waste management solutions and technologies, such as waste-to-energy. Infact, waste collection, transport and disposal methods in Saudi Arabia do not match the standards of a developed country.
Future Outlook
Vision 2030, touted as most comprehensive economic reform package in Saudi history, puts forward a strong regulatory and investment framework to develop Saudi waste-to-energy sector. An ambitious target of 3GW of energy from waste is to be achieved by 2025. A methodical introduction of modern waste management techniques like material recovery facilities, waste-to-energy systems and recycling infrastructure can significantly improve waste management scenario and can also generate good business opportunities.
To sum up, environmental issues associated with non-sanitary landfills, ineffectiveness of prevalent waste management model and rising energy demand are key drivers for development of waste-to-energy sector in Saudi Arabia.
Biomass is a key renewable energy resource that includes plant and animal material, such as wood from forests, material left over from agricultural and forestry processes, and organic industrial, human and animal wastes. The energy contained in biomass originally came from the sun. Through photosynthesis carbon dioxide in the air is transformed into other carbon containing molecules (e.g. sugars, starches and cellulose) in plants. The chemical energy that is stored in plants and animals (animals eat plants or other animals) or in their waste is called biomass energy or bioenergy.
A quick glance at popular biomass resources
What is Biomass
Biomass comes from a variety of sources which include:
Wood from natural forests and woodlands
Forestry plantations
Forestry residues
Agricultural residues such as straw, stover, cane trash and green agricultural wastes
Crop residues encompasses all agricultural wastes such as bagasse, straw, stem, stalk, leaves, husk, shell, peel, pulp, stubble, etc. Large quantities of crop residues are produced annually worldwide, and are vastly underutilised. Rice produces both straw and rice husks at the processing plant which can be conveniently and easily converted into energy.
McLeod Harvester fractionates the harvested crop into straw and graff
Significant quantities of biomass remain in the fields in the form of cob when maize is harvested which can be converted into energy. Sugar cane harvesting leads to harvest residues in the fields while processing produces fibrous bagasse, both of which are good sources of energy. Harvesting and processing of coconuts produces quantities of shell and fibre that can be utilized.
Current farming practice 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 or thermochemically processed to produce electricity and heat. Agricultural residues are characterized by seasonal availability and have characteristics that differ from other solid fuels such as wood, charcoal, char briquette. The main differences are the high content of volatile matter and lower density and burning time.
2. Animal Waste
There are a wide range of animal wastes that can be used as sources of biomass energy. The most common sources are animal and poultry manure. In the past this waste was recovered and sold as a fertilizer or simply spread onto agricultural land, but the introduction of tighter environmental controls on odour and water pollution means that some form of waste management is now required, which provides further incentives for waste-to-energy conversion.
The most attractive method of converting these organic waste materials to useful form is anaerobic digestion which gives biogas that can be used as a fuel for internal combustion engines, to generate electricity from small gas turbines, burnt directly for cooking, or for space and water heating.
3. Forestry Residues
Forestry residues are generated by operations such as thinning of plantations, clearing for logging roads, extracting stem-wood for pulp and timber, and natural attrition. Harvesting may occur as thinning in young stands, or cutting in older stands for timber or pulp that also yields tops and branches usable for biomass energy. Harvesting operations usually remove only 25 to 50 percent of the volume, leaving the residues available as biomass for energy.
Stands damaged by insects, disease or fire are additional sources of biomass. Forest residues normally have low density and fuel values that keep transport costs high, and so it is economical to reduce the biomass density in the forest itself.
4. Wood Wastes
Wood processing industries primarily include sawmilling, plywood, wood panel, furniture, building component, flooring, particle board, moulding, jointing and craft industries. Wood wastes generally are concentrated at the processing factories, e.g. plywood mills and sawmills. The amount of waste generated from wood processing industries varies from one type industry to another depending on the form of raw material and finished product.
Generally, the waste from wood industries such as saw millings and plywood, veneer and others are sawdust, off-cuts, trims and shavings. Sawdust arise from cutting, sizing, re-sawing, edging, while trims and shaving are the consequence of trimming and smoothing of wood. In general, processing of 1,000 kg of wood in the furniture industries will lead to waste generation of almost half (45 %), i.e. 450 kg of wood. Similarly, when processing 1,000 kg of wood in sawmill, the waste will amount to more than half (52 %), i.e. 520 kg wood.
5. Industrial Wastes
The food industry produces a large number of residues and by-products that can be used as biomass energy sources. These waste materials are generated from all sectors of the food industry with everything from meat production to confectionery producing waste that can be utilised as an energy source.
Solid wastes include peelings and scraps from fruit and vegetables, food that does not meet quality control standards, pulp and fibre from sugar and starch extraction, filter sludges and coffee grounds. These wastes are usually disposed of in landfill dumps.
Liquid wastes are generated by washing meat, fruit and vegetables, blanching fruit and vegetables, pre-cooking meats, poultry and fish, cleaning and processing operations as well as wine making.
These waste waters contain sugars, starches and other dissolved and solid organic matter. The potential exists for these industrial wastes to be anaerobically digested to produce biogas, or fermented to produce ethanol, and several commercial examples of waste-to-energy conversion already exist.
Pulp and paper industry is considered to be one of the highly polluting industries and consumes large amount of energy and water in various unit operations. The wastewater discharged by this industry is highly heterogeneous as it contains compounds from wood or other raw materials, processed chemicals as well as compound formed during processing. Black liquor can be judiciously utilized for production of biogas using anaerobic UASB technology.
6. Municipal Solid Wastes and Sewage
Millions of tonnes of household waste are collected each year with the vast majority disposed of in open fields. The biomass resource in MSW comprises the putrescibles, paper and plastic and averages 80% of the total MSW collected. Municipal solid waste can be converted into energy by direct combustion, or by natural anaerobic digestion in the engineered landfill.
At the landfill sites, the gas produced, known as landfill gas or LFG, by the natural decomposition of MSW (approximately 50% methane and 50% carbon dioxide) is collected from the stored material and scrubbed and cleaned before feeding into internal combustion engines or gas turbines to generate heat and power. The organic fraction of MSW can be anaerobically stabilized in a high-rate digester to obtain biogas for electricity or steam generation.
Sewage is a source of biomass energy that is very similar to the other animal wastes. Energy can be extracted from sewage using anaerobic digestion to produce biogas. The sewage sludge that remains can be incinerated or undergo pyrolysis to produce more biogas.
India’s waste-to-energy sector, which kicked off in 1987, is still searching for a successful role model, even after tens of millions of dollars of investment. In recent years, many ambitious waste-to-energy projects have been established or are being planned in different parts of the country, and it is hoped that things will brighten up in the coming years. Salman Zafar, CEO of BioEnergy Consult, talks to Power Today magazine on India’s tryst with waste-to-energy and highlights major challenges and obstacles in making waste-to-energy a success story in India.
Power Today: What are the challenges that the Waste to Energy sector faces in the current scenario where there is a rejuvenated interest in clean energy? Do you think the buzz around solar and wind power has relegated the Waste to Energy sector to the back benches?
Salman Zafar: India’s experience with waste-to-energy has been lackluster until now. The progress of waste-to-energy sector in India is hampered by multiples issues including
poor quality of municipal waste,
high capital and O&M costs of waste-to-energy systems,
lack of indigenous technology,
lack of successful projects and failure of several ambitious projects,
lack of coordination between municipalities, state and central governments,
heavy reliance on government subsidies,
difficulties in obtaining long-term Power Purchase Agreements (PPAs) with state electricity boards (SEBs)
lukewarm response of banks and financial institutions and (9) weak supply chain.
Waste-to-energy is different from solar (or wind) as it essentially aims to reduce the colossal amount of solid wastes accumulating in cities and towns all over India. In addition to managing wastes, waste-to-energy has the added advantage of producing power which can be used to meet rapidly increasing energy requirements of urban India.
In my opinion, waste-to-energy sector has attracted renewed interest in the last couple of years due to Swachch Bharat Mission, though government’s heavy focus on solar power has impacted the development of waste-to-energy as well as biomass energy sectors.
Power Today: India has a Waste to Energy potential of 17,000 MW, of which only around 1,365 MW has been realised so far. How much growth do you expect in the sector?
Salman Zafar: As per Energy Statistics 2015 (refer to http://mospi.nic.in/Mospi_New/upload/Energy_stats_2015_26mar15.pdf), waste-to-energy potential in India is estimated to be 2,556 MW, of which approximately 150 MW (around 6%) has been harnessed till March 2016.
The progress of waste-to-energy sector in India is dependent on resolution of MSW supply chain issues, better understanding of waste management practices, lowering of technology costs and flexible financial model. For the next two years, I am anticipating an increase of around 75-100 MW of installed capacity across India.
Power Today: On the technological front, what kinds of advancements are happening in the sector?
Salman Zafar: Nowadays, advanced thermal technologies like MBT, thermal depolymerisation, gasification, pyrolysis and plasma gasification are hogging limelight, mainly due to better energy efficiency, high conversion rates and less emissions. Incineration is still the most popular waste-to-energy technology, though there are serious emission concerns in developing countries as many project developers try to cut down costs by going for less efficient air pollution control system.
Power Today: What according to you, is the general sentiment towards setting up of Waste to Energy plants? Do you get enough cooperation from municipal bodies, since setting up of plants involves land acquisition and capital expenditure?
Salman Zafar: Waste-to-energy projects, be it in India or any other developing country, is plagued by NIMBY (not-in-my-backyard) effect. The general attitude towards waste-to-energy is that of indifference resulting in lukewarm public participation and community engagement in such projects.
Government should setup dedicated waste-to-energy research centres to develop lost-cost and low-tech waste to energy solutions
Lack of cooperation from municipalities is a major factor in sluggish growth of waste-to-energy sector in India. It has been observed that sometimes municipal officials connive with local politicians and ‘garbage mafia’ to create hurdles in waste collection and waste transport.
Supply of poor quality feedstock to waste-to-energy plants by municipal bodies has led to failure of several high-profile projects, such as 6 MW MSW-to-biogas project in Lucknow, which was shut down within a year of commissioning due to waste quality issues.
Power Today: Do you think that government policies are in tandem when it comes to enabling this segment? What policies need to be changed, evolved or adopted to boost this sector?
Salman Zafar: A successful waste management strategy demands an integrated approach where recycling and waste-to-energy are given due importance in government policies. Government should strive to setup a dedicated waste-to-energy research centre to develop a lost-cost and low-tech solution to harness clean energy from millions of tons of waste generated in India.
The government is planning many waste-to-energy projects in different cities in the coming years which may help in easing the waste situation to a certain extent. However, government policies should be inclined towards inclusive waste management, whereby the informal recycling community is not robbed of its livelihood due to waste-to-energy projects.
Government should also try to create favourable policies for establishment of decentralized waste-to-energy plants as big projects are a logistical nightmare and more prone to failure than small-to-medium scale venture.
Incineration is the most popular waste treatment method that transforms waste materials into useful energy. The incineration process converts waste into ash, flue gas, and heat. The type of thermal WTE technology most commonly used worldwide for municipal solid waste is the moving grate incineration. These moving grate incinerators are even sometimes referred to as as the Municipal Solid Waste Incinerators.
There are more than 1500 Waste-to-Energy plants (among 40 different countries) there is no pre-treatment of the MSW before it is combusted using a moving grate. The hot combustion gases are commonly used in boilers to create steam that can be utilized for electricity production. The excess energy that can’t be used for electricity can possibly be used for industrial purposes, such as desalination or district heating/cooling.
Benefits of Moving Grate Incineration
The moving grate incineration technology is lenient in that it doesn’t need prior MSW sorting or shredding and can accommodate large quantities and variations of MSW composition and calorific value. With over 100 years of operation experience, the moving grate incineration system has a long track record of operation for mixed MSW treatment. Between 2003 and 2020, it was reported that at least 200 moving grate incineration plants were built worldwide for MSW treatment. Currently, it is the main thermal treatment used for mixed MSW.
Compared to other thermal treatment technologies, the unit capacity and plant capacity of the moving grate incineration system is the highest, ranging from 10 to 920 tpd and 20 to 4,300 tpd. This system is able to operate 8,000 hours per year with one scheduled stop for inspection and maintenance of a duration of roughly one month.
Today, the moving grate incineration system is the only treatment type which has been proven to be capable of treating over 3,000 tpd of mixed MSW without requiring any pretreatment steps. Being composed of six lines of furnace, one of the world’s largest moving grate incineration plants has a capacity of 4,300 tpd and was installed in Singapore by Mitsubishi in 2000
Working Principle
Moving grate incineration requires that the grate be able to move the waste from the combustion chamber to allow for an effective and complete combustion. A single incineration plant is able to process thirty-five metric tons of waste per hour of treatment.
The MSW for a moving grate incinerator does not require pretreatment. For this reason, it is easier to process large variations and quantities. Most of these incineration plants have hydraulic feeders to feed as-received MSW to the combustion chamber (a moving grate that burns the material), a boiler to recover heat, an air pollution control system to clean toxins in the flus gas, and discharge units for the fly ash. The air or water-cooled moving grate is the central piece of the process and is made of special alloys that resist the high temperature and avoid erosion and corrosion.
Working principle of a grate incinerator
The waste is first dried on the grate and then burnt at a high temperature (850 to 950 degrees C) accompanied with a supply of air. With a crane, the waste itself is emptied into an opening in the grate. The waste then moves towards the ash pit and it is then treated with water, cleaning the ash out. Air then flows through the waste, cooling the grate. Sometimes grates can also be cooled with water instead. Air gets blown through the boiler once more (but faster this time) to complete the burning of the flue gases to improve the mixing and excess of oxygen.
Suitability for Developing Nations
For lower income and developing countries with overflowing landfills, the moving grate incinerator seems suitable and efficient. Moving grate incineration is the most efficient technology for a large-scale mixed MSW treatment because it is the only thermal technology that has been able to treat over 3,000 tons of mixed MSW per day. It also seems to be considerably cheaper than conventional technologies.
Compared to other types of Waste-to-Energy technologies, this type of system also shows the highest ability to handle variation of MSW characteristics. As for the other incineration technologies like gasification and pyrolysis technologies, these are either limited in small-scale, limited in material for industrial/hazardous waste treatment, requiring preprocessing of mixed MSW before feeding, which make them not suitable for large-scale mixed MSW treatment.
Conclusion
For the reduction of significant waste volume, treatment using a moving grate incinerator with energy recovery is the most common waste-to-energy technology. The moving grate’s ability to treat significant volumes of waste efficiently, while not requiring pre-treatment or sorting is a major advantage that makes this suitable for developing countries.
This technology could provide many other benefits to such nations. Implementing moving grate incinerators is most suitable for developing nations because not only will it reduce waste volume, but it would also reduce the demand for landfills, and could recover energy for electricity.
References
“A Rapidly Emerging WTE Technology: Circulating Fluid Bed Combustion”. Huang, Qunxing, Yong Chi1, and Nickolas J. Themelis. Proceedings of International Thermal Treatment Technologies (IT3), San Antonio, TX, October 2013. Columbia University. Available: http://www.seas.columbia.edu/earth/wtert/sofos/Rapid_Emerging_Tech_CFB.pdf accessed on 29 March 2016.
Kamuk, Bettina, and Jørgen Haukohl. ISWA Guidelines: Waste to Energy in Low and Middle Income Countries. Rep. International Solid Waste Association, 2013. Print.
“Municipal Solid Waste Management and Waste-to-Energy in the United States, China and Japan.” Themelis, Nickolas J., and Charles Mussche. 2nd International Academic Symposium on Enhanced Landfill Mining, Houthalen and Helchteren, Belgium, 4-16 October 2013. Enhanced Landfill Mining. Columbia University.
“Review of MSW Thermal Treatment Tecnologies.” Lai, K.C.K., I.M.C. Lo, and T.T.Z. Liu. Proceedings of the International Conference on Solid Waste 2011- Moving Towards Sustainable Resource Management, Hong Kong SAR, P.R. China, 2 – 6 May 2011. Hong Kong SAR, P.R. China. 2011. 317-321. Available: http://www.iswa.org/uploads/tx_iswaknowledgebase/10_Thermal_Technology.pdf. accessed on 14 April 2016.
UN-HABITAT, 2010. Collection of Municipal Solid Waste in Developing Countries. United Nations Human Settlements Programme (UN-HABITAT), Nairobi. Available:
The increasing clamor for energy and satisfying it with a combination of conventional and renewable resources is a big challenge. Accompanying energy problems in almost all parts of the world, another problem that is assuming critical proportions is that of urban waste accumulation. The quantity of waste produced all over the world amounted to more than 12 billion tonnes in 2006, with estimates of up to 13 billion tonnes in 2011. The rapid increase in population coupled with changing lifestyle and consumption patterns is expected to result in an exponential increase in waste generation of up to 18 billion tonnes by year 2020. Ironically, most of the wastes are disposed of in open fields, along highways or burnt wantonly.
Size of the Industry
Around 130 million tonnes of municipal solid waste (MSW) are combusted annually in over 600 waste-to-energy (WTE) facilities globally that produce electricity and steam for district heating and recovered metals for recycling. The global market for biological and thermochemical waste-to-energy technologies is expected to grow to USD 29.2 billion by 2022. Incineration, with energy recovery, is the most common waste-to-energy method employed worldwide.
Since 1995, the global WTE industry increased by more than 16 million tonnes of MSW. Over the last five years, waste incineration in Europe has generated between an average of 4% to 8% of their countries’ electricity and between an average of 10% to 15% of the continent’s domestic heat.
Advanced thermal technologies, like gasification and pyrolysis, and anaerobic digestion systems are beginning to make deep inroads in the waste-to-energy sector and are expected to increase their respective market shares on account of global interest in integrated waste management framework in urban areas. Scarcity of waste disposal sites coupled with growing waste volumes and solid waste management challenges are generating high degree of interest in energy-from-waste systems among policy-makers, urban planners, entrepreneurs, utility companies etc.
Regional Trends
Currently, the European nations are recognized as global leaders of waste-to-energy movement. They are followed behind by the Asia Pacific region and North America respectively. In 2007 there are more than 600 WTE plants in 35 different countries, including large countries such as China and small ones such as Bermuda. Some of the newest plants are located in Asia. China is witnessing a surge in waste-to-energy installations and has plans to establish 125 new waste-to-energy plants during the twelfth five-year plan ending 2015.
Incineration is the most common waste-to-energy method used worldwide.
The United States processes 14 percent of its trash in WTE plants. Denmark, on the other hand, processes more than any other country – 54 percent of its waste materials. As at the end of 2008, Europe had more than 475 WTE plants across its regions – more than any other continent in the world – that processes an average of 59 million tonnes of waste per annum. In the same year, the European WTE industry as a whole had generated revenues of approximately US$4.5bn.
Legislative shifts by European governments have seen considerable progress made in the region’s WTE industry as well as in the implementation of advanced technology and innovative recycling solutions. The most important piece of WTE legislation pertaining to the region has been the European Union’s Landfill Directive, which was officially implemented in 2001 which has resulted in the planning and commissioning of an increasing number of WTE plants over the past five years.
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