ELECTRONIC WASTE TO ENERGY Peter U. Ndukwe*, Onyinyechi C. Nwadiuko, Lebe A. Nnanna, Francis O. Nwosu Physics/Electronics Department, Abia State Polytechnic, P. M. B. 7166, Aba, Abia State *Corresponding Author’s email: ndukwepeter28u@yahoo.com Tel: 08033776084 ABSTRACT Among the several waste products, and considering the rate of growth in modern-day inventions, there is a surging increase in waste of electrical and electronics gadget; electronic waste (e-waste). E-waste comprises of a multitude of electronic components, some containing high enough levels of toxic substances that can have an adverse effect on human health and the environment if not properly handled. But this e-waste keeps on increasing as the world continues to modernize and our dependence on the use of energy keeps growing exponentially, so the need for the conversion of this growing e-waste to energy comes in to play and the conversion is done by the process of plasma gasification. This paper provides a concise overview on e-waste, causes, e-waste as an alternative source of energy and its benefits. Key words: e-waste, plasma gasification, waste management, alternative energy. INTRODUCTION Electrical and electronic gadgets have become the fastest growing equipments in the world today. The rate at which urbanization and demand for consumer goods are increasing has led to the increase in the production of Electrical and electronic equipment (EEE) (Ramesh et al, 2007). New electronic gadgets and appliances have infiltrated every aspect of our daily lives, providing our society with more comfort, health and security and with easy information acquisition and exchange (Sinha, 2007). These new electronic gadgets are after some time (years) becomes electronic waste. These wastes are known as Electronic waste, e-waste, e-scrap, or waste electrical and electronic equipment (WEEE). They include; old, end-of-life electronic appliances such as computers, laptops, TVs, DVD players, mobile phones, mp3 players, LCDs, refrigerators etc., which have been disposed by their original users (eWaste Guide, 2008 and Sinha, 2007). The increasing electronic equipment demanded by the developing countries like Nigeria, make electronic waste the fastest waste streams in the country (Messerle and Ustimenko, 2007) and is posing a serious challenge in disposal and recycling. Most developed countries now use most undeveloped countries as a dumping ground for electronic waste. They 1 find it convenient and economical to export waste into these countries as a form of trade or business transaction (Ramesh et al, 2007). On the other hand, individuals, groups, co-operate bodies or companies from undeveloped countries like Nigeria import these electronic equipment as second hand goods into the country thereby creating further work on waste management. An estimated 50 million tons of Electronic waste are produced in each year around the globe and 40 million out of it are sent to the developing countries (Sthiannopkao and Wong, 2012) and in which about 1000000 tons are sent to Nigeria each year. According to a report by UNEP titled, "Recycling - from Electronic waste to Resources," the amount of electronic waste being produced - including mobile phones and computers - could rise by as much as 500 percent over the next decade in some countries, such as India, China and Nigeria(United Nations News Service , 2010). In a report(Ghana electronic waste Country Assessment, 2011) found that out of 215,000 tons of electronics imported to Ghana, 30% were brand new and 70% were used. Of the used product, the study concluded that 15% was not reused and was scrapped or discarded. All these have made electronic waste management an issue of great concern. CAUSES OF ELECTRONIC WASTE The following are the major causes of electronic waste: DEVELOPMENT: It is estimated that there are over a billion personal computers and mobile phones in the world today(Sthiannopkao and Wong, 2012). In developing countries these have an average life span of only two years. In the United States alone there are over 300 million obsolete computers. Not only in the developed countries, but the developing countries too have faced a step rise in sales or moreover wastage in this industry. It is believed that sales of computers, mobile phones and other electronic devices have gone up by 400% in developing countries as well (Sthiannopkao and Wong, 2012). So the question of disposal of large numbers of "end of life" computers and other IT equipment must be harnessed and in a good way to improve energy. All of this is because of development caused by globalization. TECHNOLOGY: In this modern era, technology is growing as the speed of light. This growing technology results in the coming of newer products and appliances. The major reason for this can be none other than MNC’s (Multinational corporations). MNC's now a days are so powerful that they can influence the whole market system of a country in no time. It is these MNC's that provide better technology in the world. Moreover, they have the power to decide price and 2 quality, and recently have increased quality of products at a reduced price. The keep on providing high sophisticated technology that causes increase in modern technology and electronic waste as well. HUMAN MENTALITY: The quest to be seen, power, money and for newer materials has made technology and development to be on the increase. Computer and Phone companies like the other companies for instance, in course to satisfy human quest has produced different models of mobile phone and people tends to substitute their older phones with the newer ones and these older phones that are not in use is termed electronic waste. This increase in human quest causes an increase in electronic waste that can be addressed through plasma gasification in the area of energy. POPULATION: Nigeria like the other countries of the world has witnessed increase in population in the past years and is even more in the resent years; this increase has triggered the demand for electronic gadgets. It’s simple to understand by one of the simplest theories of unitary method, that “if one person buys one electronic gadget, two will buy two”, so with increasing population the number of electronic gadgets would also increase with this method. So we can conclude that with increasing population the amount of e waste would also increase because these electronic devices we bought after sometime would be thrown with the introduction of better technological devices which we would equally buy. Moreover all these are interlinked with each other and together contribute to a major environmental concern caused by electronic waste which is on the high side in the country but if properly handled will boast the source of energy in the country. Since the amount of electronic waste generated is in increasing order, proper management should be adopted in our society. ELECTRONIC WASTE MANAGEMENT RECYCLING Today the electronic waste recycling business is in all areas of both the developed and developing world at large and is a rapidly consolidating business. Part of this evolution has involved greater diversion of electronic waste from energy-intensive downcycling processes (e.g., conventional recycling), where equipment is reverted to a raw material form. This 3 recycling is done by sorting, dismantling, and recovery of valuable materials (20) and this diversion is achieved through reuse and refurbishing. The environmental and social benefits of reuse include diminished demand for new products and virgin raw materials (with their own environmental issues); larger quantities of pure water and electricity for associated manufacturing; less packaging per unit; availability of technology to wider swaths of society due to greater affordability of products; and diminished use of landfills. Audiovisual components, televisions, VCRs, stereo equipment, mobile phones, other handheld devices, and computer components contain valuable elements and substances suitable for reclamation, including lead, copper, and gold. One of the major challenges is recycling the printed circuit boards from the electronic wastes. But cryogenic decomposition which is a potential alternative recycling method for printed circuit board scraps (Sthiannopkao and Wong, 2012 and Yuan, 2012) that involve low temperature and the use of liquid nitrogen has been studied and other methods are still under investigation. GASIFICATION Gasification is the conversion of a solid or liquid into a gas at high temperature in a controlled amount of oxygen (Solange, 2011). Potential exists for the gasification of the waste material mined from electronics components. This material exists in either a solid or semisolid state. The resulting gas mixture from the gasification process is referred to as synthesis gas or syngas is a fuel. Syngas is a mixture of carbon monoxide and hydrogen that combusts cleanly into water vapor and carbon dioxide or may be converted to methane via the Sabatier process or gasoline/ diesel-like synthetic fuels via the Fischer–Tropsch process (Speight, 2008). The Sabatier process is an exothermic reaction of hydrogen and carbon dioxide at high temperatures and pressures in the presence of a nickel- or ruthenium-containing catalyst to produce methane and water: CO2 + 4H2 2H2O + CH4 In the Fischer–Tropsch process a catalyzed chemical reaction in which synthesis gas is converted into liquid hydrocarbons of various forms occurs. Chemically, the process is represented as follows: 4 nCO + (2n+1)H2 CnH(2n+2) + nH2O The resulting hydrocarbon products are refined to produce the desired synthetic fuel. These liquid fuels formed by the Fischer–Tropsch process burn much cleaner and are environmentally more acceptable (Speight, 2008). CONVENTIONAL GASIFICATION PROCESS Gasification offers a wide scope for recovering products from electronic waste in that the gases, oils and solid char from gasification can not only be used as a fuel but also purified and used as a feedstock for petrochemicals and other applications (Speight, 2008). The principle behind waste gasification and the production of gaseous fuels is that waste contains carbon and it is this carbon that is converted to gaseous products via gasification chemistry. Thus, when waste is fed to a gasifier, water, and volatile matter are released and a char residue is left to react further. The product gas generally contains large amounts of hydrogen and carbon monoxide and a small amount of methane, as well as carbon dioxide and steam. In addition, a significant amount of other organic components known as tar are formed. Gasification also produces a stable granulate instead of an ash that can be more easily and safely utilized. Gasification can be used in conjunction with gas engines to obtain higher conversion efficiencies than conventional fossil-fuel energy generation. By displacing fossil fuels, gasification can help meet renewable energy target and address the issue of global warming. In gasification, combustion of the waste is prevented by the limited oxygen supply. Gasiffiers are usually of a fixed-bed type (updraft or downdraft). This design is plagued by transport problems within the reactor bed and in the shaft to the ash outlet, such as ash sintering. The temperature within the reactor reaches 27001C, at which point molecular dissociation takes place. The pollutants that were contained in the waste such as dioxins, furans as well as pathogens are completely cracked into harmless compounds. Metal components in the waste are converted into an iron alloy. The mineral fraction is reduced to a non- leaching vitrified glass, used for road construction and/or further processed into a mineral wool for insulation. All of the 5 organic material is fully converted to a fuel quality synthesis gas which can be used to produce electrical energy, heat, methanol, or used in the production of various other chemical compounds. Under certain conditions heat from the reactor could be used for industrial steam production or in water-desalination plants. ELECTRONIC WASTE TO ENERGY PLASMA GASIFICATION One of the increasingly popular types of gasification is plasma gasification. Plasma gasification is a process which converts organic matter into synthetic gas(Moustakasa et al,. 2013) electricity(Bratsev et al,. 2006) and slag(Moustakasa et al,. 2013) using plasma. A plasma torch powered by an electric arc is used to ionize gas and catalyze organic matter into synthetic gas and solid waste (slag)(Moustakasa et al, 2013, Kalinenkoet al, 1993 and Messerle & Ustimenko, 2007).Plasma gasification is used commercially as a form of waste treatment and has been tested for the gasification of biomass, solid hydrocarbons and electronic waste such as coal, oil sands,oil shale and mobile phones(Kalinenko, et al, 1993). Plasma gasification technology has been shown to be an effective and environmentally friendly method for solid-waste treatment and energy utilization. It is a no incineration thermal process that uses extremely high temperatures in a partial oxygen environment to decompose completely the input waste material into very simple molecules. The products of the process are a fuel or gas known as synthesis gas and an inert vitreous material known as slag.This gas then enters the synthesis-gas-cleaning system. Gas cleaning refers to the process of removing acid gases, suspended particulates, heavy metals and moisture from the synthesis gas prior to entering the energy-recovery system where power, steam and synthetic fuels can be obtained (Moustakasa et al, 2013). Plasma gasification uses an external heat source to gasify the waste, resulting in very little combustion. Almost all of the carbon is converted to fuel synthesis gas. The high operating temperatures (above 18001C) allow for the breaking down of all tars, char and dioxins. The exit gas from the reactor is cleaner and there is no ash at the bottom of the reactor (Moustakasa et al, 2013). The waste feed subsystem is used for the treatment of each type of waste in order to meet the inlet requirements of the plasma furnace. For example, for a waste material with high 6 moisture content, a drier will be required. However, a typical feed system consists of a shredder for solid-waste size reduction prior to entering the plasma furnace. The plasma furnace is the central component of the system where gasification and vitrification takes place. Plasma torches are mounted at the bottom of the reactor; they provide high-temperature air (almost three times higher than traditional combustion temperatures) that allows for the gasification of the waste materials. Below are the diagram of a basic structure of plasma gasifier and the Schematic diagram of a waste-to energy process using plasma gasification. Fig 1. Structure of plasma gasifier Combustion Chamber Plasma Gasifier Synthesis gas Power Air Compressor Waste Cleaner Crusher Drier Air Electricity Exhaust Gases Slag Fig 2. Schematic diagram of a waste-to energy process using plasma gasification. 7 HOW PLASMA GASIFICATION WORKS Two torches are used in the plasma reactor together with a gas (oxygen, helium or air) to generate the plasma. The torches that extend into the plasma furnace are fitted with graphite electrodes. An electric current is passed through the electrodes and an electric arc is generated between the tip of the electrodes and the conducting receiver which is the slag at the bottom of the furnace (Solange, 2011). Because of the electrical resistivity across the system, significant heat is required to strip away electrons from the molecules of the gas introduced, resulting in an ionized superheated gas stream or plasma. This gas exits the torch at temperatures up to 10 0001C (Mountouris, 2006). At these temperatures, garbage melts. Molecules break down in a process called molecular dissociation. When molecules are exposed to intense energy (like the heat generated by a plasma torch), the molecular bonds holding them together becomes excited and break apart. Only elemental components of the molecules are left (Solange, 2011). Organic molecules (those that are carbon-based) become volatilized, or turn into gases. This synthetic gas (syngas) can be used as a fuel source. Inorganic compounds melt down and become vitrified, or converted into a hard, glassy substance similar in appearance and weight to obsidian. Metals melt down as well, combining with the rest of the inorganic matter (called slag). Plasma waste converters can treat almost any kind of waste, including some traditionally difficult waste materials. It can treat medical waste or chemically-contaminated waste and leave nothing but gases and slag (Solange, 2011). Because it breaks down these dangerous wastes into their basic elements, they can be disposed of safely. Plasma processing of waste is ecologically clean. The lack of oxygen prevents toxic formations. The high temperatures in a reactor prevent the main elements of gas from forming toxic compounds such as furans, dioxins, NO2, or sulfur dioxide. Water filtration removes ash and gaseous pollutants. Gasification reactors operate at negative pressure (Moustakasa et al, 2013) and recovers both (Tendler et al, 2005) gaseous and solid resources. Advantages of plasma gasification The main advantages of plasma technologies for waste treatment are: Clean destruction of hazardous waste(Tendler et al, 2005) 8 preventing hazardous waste from reaching landfills(Lemmens et al., 2007,Mountouris et al, 2008) no harmful emissions of toxic waste(Lemmens et al., 2007) production of clean alloyed slag which could be used as construction material(Mountouris et al., 2008) processing of organic waste into combustible syngas for electric power and thermal energy(Leal-Quirós, 2004) and production of value-added products (metals) from slag(Jimbo, 2013) Disadvantages of plasma gasification Main disadvantages of plasma technologies for waste treatment are: Large initial investment costs relative to landfill(Pourali, 2010) The plasma flame reduces the diameter of its sampler orifice over time, necessitating occasional maintenance.(Leal-Quirós, 2013) BENEFITS AND ADVANTAGES OF RECYCLE ELECTRONIC WASTE Recycling raw materials from end-of-life electronics is the most effective solution to the growing electronic waste problem. Recycling recovers most electronic materials that can be use for future purpose from the electronic waste devices. By recycling electronic waste devices, natural resources are conserved (energy is saved) and air and water pollution caused by hazardous disposal of electronic waste is avoided. Furthermore, recycling reduces the amount of greenhouse gas emissions caused by manufacturing of new products (Wath et al, 2011). Safe recycling of outdated electronics promotes sound management of toxic chemicals such as lead and mercury. Recycling creates jobs for professional recyclers and refurbishers and creates new markets for the valuable components that are dismantled. Saves landfill space. Electronic waste is a growing waste stream. By recycling these items, landfill space is conserved. 9 Recycling equally reduces the dangers to human health and the environment that disposed and dismantled electronics can create. 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