Waste-to-Energy in Saudi Arabia

waste-jeddahUrban 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.

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.

Waste-to-Energy in India: An Interview with Salman Zafar

waste-mountainIndia’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

  1. poor quality of municipal waste,
  2. high capital and O&M costs of waste-to-energy systems,
  3. lack of indigenous technology,
  4. lack of successful projects and failure of several ambitious projects,
  5. lack of coordination between municipalities, state and central governments,
  6. heavy reliance on government subsidies,
  7. difficulties in obtaining long-term Power Purchase Agreements (PPAs) with state electricity boards (SEBs)
  8. 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

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.

Note: This interview was originally published in June 2016 edition of Power Today magazine. The unabridged version is available at this link

Waste-to-Energy in China: Perspectives

garbage-chinaChina is the world’s largest MSW generator, producing as much as 175 million tons of waste every year. With a current population surpassing 1.37 billion and exponential trends in waste output expected to continue, it is estimated that China’s cities will need to develop an additional hundreds of landfills and waste-to-energy plants to tackle the growing waste management crisis. China’s three primary methods for municipal waste management are landfills, incineration, and composting. Nevertheless, the poor standards and conditions they operate in have made waste management facilities generally inefficient and unsustainable. For example, discharge of leachate into the soil and water bodies is a common feature of landfills in China. Although incineration is considered to be better than landfills and have grown in popularity over the years, high levels of toxic emissions have made MSW incineration plants a cause of concern for public health and environment protection.

Prevalent Issues

Salman Zafar, a renowned waste management, waste-to-energy and bioenergy expert was interviewed to discuss waste opportunities in China. As Mr. Zafar commented on the current problems with these three primary methods of waste management used by most developing countries, he said, “Landfills in developing countries, like China, are synonymous with huge waste dumps which are characterized by rotting waste, spontaneous fires, toxic emissions and presence of rag-pickers, birds, animals and insects etc.” Similarly, he commented that as cities are expanding rapidly worldwide, it is becoming increasingly difficult to find land for siting new landfills. On incineration, Zafar asserted that this type of waste management method has also become a controversial issue due to emission concerns and high technology costs, especially in developing countries. Many developers try to cut down costs by going for less efficient air pollution control systems”. Mr. Zafar’s words are evident in the concerns reflected in much of the data ­that waste management practices in China are often poorly monitored and fraudulent, for which data on emission controls and environmental protection is often elusive.

Similarly, given that management of MSW involves the collection, transportation, treatment and disposal of waste, Zafar explains why composting has also such a small number relative to landfills for countries like China. He says, “Composting is a difficult proposition for developing countries due to absence of source-segregation. Organic fraction of MSW is usually mixed with all sorts of waste including plastics, metals, healthcare wastes and industrial waste which results in poor quality of compost and a real risk of introduction of heavy metals into agricultural soils.” Given that China’s recycling sector has not yet developed to match market opportunities, even current treatment of MSW calls for the need of professionalization and institutionalization of the secondary materials industry.

While MSW availability is not an issue associated with the potential of the resource given its dispersion throughout the country and its exponential increase throughout, around 50 percent of the studies analyzed stated concerns for the high moisture content and low caloric value of waste in China, making it unattractive for WTE processes. Talking about how this issue can be dealt with, Mr. Zafar commented that a plausible option to increase the calorific value of MSW is to mix it with agricultural residues or wood wastes. Thus, the biomass resources identified in most of the studies as having the greatest potential are not only valuable individually but can also be processed together for further benefits.

Top Challenges

Among the major challenges on the other hand, were insufficient or elusive data, poor infrastructure, informal waste collection systems and the lack of laws and regulations in China for the industry. Other challenges included market risk, the lack of economic incentives and the high costs associated with biomass technologies. Nevertheless, given that the most recurring challenges cited across the data were related to infrastructure and laws and regulations, it is evident that China’s biomass policy is in extreme need of reform.

China’s unsustainable management of waste and its underutilized potential of MSW feedstock for energy and fuel production need urgent policy reform for the industry to develop. Like Mr. Zafar says, “Sustainable waste management demands an integration of waste reduction, waste reuse, waste recycling, and energy recovery from waste and landfilling. It is essential that China implements an integrated solid waste management strategy to tackle the growing waste crisis”.

Future Perspectives

China’s government will play a key role in this integrated solid waste management strategy. Besides increased cooperation efforts between the national government and local governments to encourage investments in solid waste management from the private sector and foster domestic recycling practices, first, there is a clear need to establish specialized regulatory agencies (beyond the responsibilities of the State Environmental Protection Administration and the Ministry of Commerce) that can provide clearer operating standards for current WTE facilities (like sanitary landfills and incinerators) as well as improve the supervision of them.

It is essential that China implements an integrated solid waste management strategy to tackle the growing waste crisis

It is essential that China implements an integrated solid waste management strategy to tackle the growing waste crisis

Without clear legal responsibility assigned to specialized agencies, pollutant emissions and regulations related to waste volumes and operating conditions may continue to be disregarded. Similarly, better regulation in MSW management for efficient waste collection and separation is needed to incentivize recycling at the individual level by local residents in every city. Recycling after all is complementary to waste-to-energy, and like Salman Zafar explains, countries with the highest recycling rates also have the best MSW to energy systems (like Germany and Sweden). Nevertheless, without a market for reused materials, recycling will take longer to become a common practice in China. As Chinese authorities will not be able to stop the waste stream from growing but can reduce the rate of growth, the government’s role in promoting waste management for energy production and recovery is of extreme importance.

Moving Grate Incineration: Preferred WTE Technology

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 (MSWIs). As of August 2013, of more than 1000 of 1200 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

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 2011, it was reported that at least 106 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 commonly used form of waste-to-energy (WTE) 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.
“Incineration.” Waste Management Resources. Waste Management Resources. Available: http://www.wrfound.org.uk/articles/incineration.html 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. Available: http://elfm.eu/Uploads/ELFM/FILE_73D907E9-8225-4B93-91F8-10F71F59B793.PDF accessed on 29 March 2016.
“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:
http://www.eawag.ch/fileadmin/Domain1/Abteilungen/sandec/E-Learning/Moocs/Solid_Waste/W1/Collection_MSW_2010.pdf.
World Bank, 2012. What a Waste: A Global Review of Solid Waste Management. Urban Development Series Knowledge Papers. Available: http://documents.worldbank.org/curated/en/2012/03/16537275/waste-global-review-solid-wastemanagement. accessed on 14 April 2016.

Solid Waste Management in Nigeria

waste-nigeriaSolid waste management is the most pressing environmental challenge faced by urban and rural areas of Nigeria. Nigeria, with population exceeding 170 million, is one of the largest producers of solid waste in Africa. Despite a host of policies and regulations, solid waste management in the country is assuming alarming proportions with each passing day.

Nigeria generates more than 32 million tons of solid waste annually, out of which only 20-30% is collected. Reckless disposal of MSW has led to blockage of sewers and drainage networks, and choking of water bodies. Most of the wastes is generated by households and in some cases, by local industries, artisans and traders which litters the immediate surroundings. Improper collection and disposal of municipal wastes is leading to an environmental catastrophe as the country currently lack adequate budgetary provisions for the implementation of integrated waste management programmes across the States.

According to the United Nations Habitat Watch, African city populations will more than triple over the next 40 years. African cities are already inundated with slums; a phenomenon that could triple urban populations and spell disaster, unless urgent actions are initiated. Out of the 36 states and a federal capital in the country, only a few have shown a considerable level of resolve to take proactive steps in fighting this scourge, while the rest have merely paid lip services to issues of waste management indicating a huge lack of interest to develop the waste sector.

Scenario in Lagos

Lagos State, the commercial hub of Nigeria, is the second fastest growing city in Africa and seventh in the world.  The latest reports estimate its population to be more than 21million making it the largest city in entire Africa.  With per capita waste generation of 0.5 kg per day, the city generates more than 10,000 tons of urban waste every day.

Despite being a model for other states in the country, municipal waste management is a big challenge for the Lagos State Waste Management Agency (LAWMA) to manage alone, hence the need to engage the services of private waste firms and other franchisee to reduce the burden of waste collection and disposal. One fundamental issue is the delayed collection of household solid waste.  In some cases, the wastes are not collected until after a week or two, consequently, the waste bin overflows and litters the surroundings.

Improper waste disposal and lack of reliable transport infrastructure means that collected wastes are soon dispersed to other localities. Another unwelcome practice is to overload collection trucks with 5-6 tons of waste to reduce the number of trips; this has necessitated calls by environmental activist to prevail on the relevant legislature to conform to the modern waste transportation standard.

Situation in Oyo

Away from Lagos State, Oyo is another ancient town in Nigeria with an estimated population of six million people. Here, solid waste is regulated by the Oyo State Solid Waste Management Authority (OYOWMA). Unlike Lagos State, Oyo State does not have a proper waste management scheme that cuts across the nooks and crannies of the state, apart from Ibadan, the capital city, people from other towns like Ogbomoso and Iseyin resort to waste burning. In case the waste generators feels that the amount being charged by the waste franchisee is beyond their means, they dump the waste along flood paths thus compounding the waste predicament.

Burning of municipal wastes is a common practice in Nigeria

Burning of municipal wastes is a common practice in Nigeria

Kano and Rivers State with its fair share of population also suffers similar fate in controlling and managing solid waste. Generally speaking, population increase in Nigeria has led to an unprecedented growth in its economy but with a devastating effect on the environment as more wastes are generated due to the need for housing, manufacturing industries and a boost in trade volume.

Future Perspectives

The government at the federal level as a matter of urgency needs to revive its regulatory framework that will be attractive for private sectors to invest in waste collection, recycling and reusing.  The environmental health officer’s registration council of Nigeria would do well to intensify more effort to monitor and enforce sanitation laws as well as regulate the activities of the franchisees on good sustainable practices.

Taking the advocacy further on waste management, to avoid littering the environment, some manufacturing companies (e.g. chemical and paint industry) have introduced a recall process that will reward individuals who returns empty/used plastic containers. This cash incentive has been proven over time to validate the waste to wealth program embarked upon by the manufacturing companies. It is also expected that the government will build more composting and recycling plants in addition to the ones in Ekiti and Kano State to ensure good sustainable waste management.

Waste management situation in Nigeria currently requires concerted effort to sensitize the general public on the need for proper disposal of solid waste. Also, the officials should be well trained on professionalism, service delivery and ensure that other states within the country have access to quality waste managers who are within reach and can assist on the best approach to managing their waste before collection.

Trends in Waste-to-Energy Industry

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 reach USD 7.4 billion in 2013 and 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 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.

Municipal Solid Wastes in Bahrain

The Kingdom of Bahrain is an archipelago of around 33 islands, the largest being the Bahrain Island. The population of Bahrain is around 1.2 million marked by population density of 900 persons per km2, which is the highest in the entire GCC region. The country has the distinction of being one of the highest per capita municipal solid waste generators worldwide estimated to be 1.67 – 1.80 kg per person per day. Infact, Bahrain produces largest amount of waste per person among GCC countries despite being the smallest nation in the region. Rising population, high waste generation growth rate, limited land availability and scarcity of waste disposal sites has made solid waste management a highly challenging task for Bahrain’s policy-makers, urban planners and municipalities.

Municipal Solid Wastes in Bahrain

Bahrain generates more than 1.2 million tons of solid wastes every year. Daily garbage production across the tiny Gulf nation exceeds 4,500 tons. Municipal solid waste is characterized by high percentage of organic material (around 60 percent) which is mainly composed of food wastes. Presence of high percent of recyclables in the form of paper (13 percent), plastics (7 percent) and glass (4 percent) makes Bahrain’s MSW a good recycling feedstock, though informal sectors are currently responsible for collection of collection of recyclables and recycling activities

The Kingdom of Bahrain is divided into five governorates namely Manama, Muharraq, Middle, Southern and Northern. Waste collection and disposal operation in Bahrain is managed by a couple of private contractors. Gulf City Cleaning Company is active in Muharraq and Manama while Sphinx Services is responsible for Southern, Middle, and Northern Areas. The prevalent solid waste management scenario is to collect solid waste and dump it at the municipal landfill site at Askar.

Askar, the only existing landfill/dumpsite in Bahrain, caters to municipal wastes, agricultural wastes and non-hazardous industrial wastes. Spread over an area of more than 700 acres, the landfill is expected to reach its capacity within the next few years. The proximity of Askar landfill to urban habitats has been a cause of major environmental concern. Waste accumulation is increasing at a rapid pace which is bound to have serious impacts on air, soil and groundwater quality in the surrounding areas.

Conclusions

The Kingdom of Bahrain is grappling with waste management problems arising out of high population growth rate, rapid industrialization, high per capita waste generation, unorganized SWM sector, limited land resources and poor public awareness. The government is trying hard to improve waste management scenario by launching recycling initiatives, waste-to-energy project and public awareness campaign. However more efforts, in the form of effective legislation, large-scale investments, modern SWM technology deployment and environmental awareness, are required from all stake holders to implement a sustainable waste management system in Bahrain.

Solid Wastes in the Middle East

The high rate of population growth, urbanization and economic expansion in the Middle East is not only accelerating consumption rates but also increasing the generation rate of all  sorts of waste. Bahrain, Saudi Arabia, UAE, Qatar and Kuwait rank in the top-ten worldwide in terms of per capita solid waste generation. The gross urban waste generation quantity from Middle East countries is estimated at more than 150 million tons annually.

Saudi Arabia produced 13 million tons of garbage in 2009. With an approximate population of about 28 million, the kingdom produces approximately 1.3 kilograms of waste per person every day.  According to a recent study conducted by Abu Dhabi Center for Waste Management, the amount of waste in UAE totaled 4.892 million tons, with a daily average of 6935 tons in the city of Abu Dhabi, 4118 tons in Al Ain and 2349 tons in the western region. Countries like Kuwait, Bahrain and Qatar have astonishingly high per capita waste generation rate, primarily because of high standard of living and lack of awareness about sustainable waste management practices.

In Middle East countries, huge quantity of sewage sludge is produced on daily basis which presents a serious problem due to its high treatment costs and risk to environment and human health. On an average, the rate of wastewater generation is 80-200 litres per person each day and sewage output is rising by 25 percent every year. According to estimates from the Drainage and Irrigation Department of Dubai Municipality, sewage generation in the Dubai increased from 50,000 m3 per day in 1981 to 400,000 m3 per day in 2006.

Waste-to-Energy Prospects

Municipal solid waste in the Middle East is mainly comprised of organics, paper, glass, plastics, metals, wood etc. Municipal solid waste can be converted into energy by conventional technologies (such as incineration, mass-burn and landfill gas capture) or by modern conversion systems (such as anaerobic digestion, gasification and pyrolysis).

At the landfill sites, the gas produced by the natural decomposition of MSW is collected from the stored material and scrubbed and cleaned before feeding into internal combustion engines or gas turbines to generate heat and power. In addition, the organic fraction of MSW can be anaerobically stabilized in a high-rate digester to obtain biogas for electricity or steam generation.

Anaerobic digestion is the most preferred option to extract energy from sewage, which leads to production of biogas and organic fertilizer. The sewage sludge that remains can be incinerated or gasified/pyrolyzed to produce more energy. In addition, sewage-to-energy processes also facilitate water recycling.

Thus, municipal solid waste can also be efficiently converted into energy and fuels by advanced thermal technologies. Infact, energy recovery from MSW is rapidly gaining worldwide recognition as the 4th R in sustainable waste management system – Reuse, Reduce, Recycle and Recover.

Gasification of Municipal Wastes

utishinai-gasification-plantGasification of municipal wastes involves the reaction of carbonaceous feedstock with an oxygen-containing reagent, usually oxygen, air, steam or carbon dioxide, generally at temperatures above 800°C. The process is largely exothermic but some heat may be required to initialise and sustain the gasification process. The main product of the gasification process is syngas, which contains carbon monoxide, hydrogen and methane. Typically, the gas generated from gasification has a low heating value (LHV) of 3 – 6 MJ/Nm3.The other main product produced by gasification is a solid residue of non-combustible materials (ash) which contains a relatively low level of carbon. Syngas can be used in a number of ways, including:

  • Syngas can be burned in a boiler to generate steam for power generation or industrial heating.
  • Syngas can be used as a fuel in a dedicated gas engine.
  • Syngas, after reforming, can be used in a gas turbine
  • Syngas can also be used as a chemical feedstock.

Gasification has been used worldwide on a commercial scale for several decades by the chemical, refining, fertilizer and electric power industries. MSW gasification plants are relatively small-scale, flexible to different inputs and modular development. The quantity of power produced per tonne of waste by gasification process is larger than when applying the incineration method. The most important reason for the growing popularity of gasification of municipal wastes has been the increasing technical, environmental and public dissatisfaction with the performance of conventional incinerators.

Plasma Gasification

Plasma gasification uses extremely high temperatures in an oxygen-starved environment to completely decompose input waste material into very simple molecules in a process similar to pyrolysis. The heat source is a plasma discharge torch, a device that produces a very high temperature plasma gas. It is carried out under oxygen-starved conditions and the main products are vitrified slag, syngas and molten metal.

plasma-gasification

Vitrified slag may be used as an aggregate in construction; the syngas may be used in energy recovery systems or as a chemical feedstock; and the molten metal may have a commercial value depending on quality and market availability. The technology has been in use for steel-making and is used to melt ash to meet limits on dioxin/furan content. There are several commercial-scale plants already in operation in Japan for treating MSW and auto shredder residue.

Advantages of Gasification

There are numerous solid waste gasification facilities operating or under construction around the world. Gasification of solid wastes has several advantages over traditional combustion processes for MSW treatment. It takes place in a low oxygen environment that limits the formation of dioxins and of large quantities of SOx and NOx. Furthermore, it requires just a fraction of the stoichiometric amount of oxygen necessary for combustion. As a result, the volume of process gas is low, requiring smaller and less expensive gas cleaning equipment.

The lower gas volume also means a higher partial pressure of contaminants in the off-gas, which favours more complete adsorption and particulate capture. Finally, gasification generates a fuel gas that can be integrated with combined cycle turbines, reciprocating engines and, potentially, with fuel cells that convert fuel energy to electricity more efficiently than conventional steam boilers.

Disadvantages of Gasification

The gas resulting from gasification of municipal wastes contains various tars, particulates, halogens, heavy metals and alkaline compounds depending on the fuel composition and the particular gasification process. This can result in agglomeration in the gasification vessel, which can lead to clogging of fluidised beds and increased tar formation. In general, no slagging occurs with fuels having ash content below 5%. MSW has a relatively high ash content of 10-12%.

Resource Base for Biogas Plants

Anaerobic digestion is the natural biological process which stabilizes organic waste in the absence of air and transforms it into biofertilizer and biogas. Almost any organic material can be processed with anaerobic digestion.

Anaerobic digestion is particularly suited to wet organic material and is commonly used for effluent and sewage treatment.  This includes biodegradable waste materials such as waste paper, grass clippings, leftover food, sewage and animal waste. Large quantity of waste, in both solid and liquid forms, is generated by the industrial sector like breweries, sugar mills, distilleries, food-processing industries, tanneries, and paper and pulp industries. Poultry waste has the highest per ton energy potential of electricity per ton but livestock have the greatest potential for energy generation in the agricultural sector.

Agricultural Feedstock

  • Animal manure
  • Energy crops
  • Algal biomass
  • Crop residues

Community-Based Feedstock

  • Organic fraction of MSW (OFMSW)
  • MSW
  • Sewage sludge
  • Grass clippings/garden waste
  • Food remains
  • Institutional wastes etc.

 Industrial Feedstock

  • Food/beverage processing
  • Dairy
  • Starch industry
  • Sugar industry
  • Pharmaceutical industry
  • Cosmetic industry
  • Biochemical industry
  • Pulp and paper
  • Slaughterhouse/rendering plant etc.

Anaerobic digestion is particularly suited to wet organic material and is commonly used for effluent and sewage treatment. Almost any organic material can be processed with anaerobic digestion process. This includes biodegradable waste materials such as waste paper, grass clippings, leftover food, sewage and animal waste. The exception to this is woody wastes that are largely unaffected by digestion as most anaerobic microorganisms are unable to degrade lignin.

Anaerobic digesters can also be fed with specially grown energy crops such as silage for dedicated biogas production. A wide range of crops, especially C-4 plants, demonstrate good biogas potentials. Corn is one of the most popular co-substrate in Germany while Sudan grass is grown as an energy crop for co-digestion in Austria. Crops like maize, sunflower, grass, beets etc., are finding increasing use in agricultural digesters as co-substrates as well as single substrate.

A wide range of organic substances are anaerobically easily degradable without major pretreatment. Among these are leachates, slops, sludges, oils, fats or whey. Some wastes can form inhibiting metabolites (e.g.NH3) during anaerobic digestion which require higher dilutions with substrates like manure or sewage sludge. A number of other waste materials often require pre-treatment steps (e.g. source separated municipal organic waste, food residuals, expired food, market wastes and crop residues).