Solid waste as renewable source of energy: current and future possibility in Algeria

Fortunately, Algeria has enormous potential of solar energy. More than 2,000,000 km² receives a yearly sunshine exposure equivalent to 2,500 KWh/m². The mean yearly sunshine duration varies from a low of 2,650 h on the coastal line to 3,500 h in the south.

In addition, as shown in Table 1, the potential of daily solar energy is important. It varies from a low average of 4.66 kWh/m² in the north to a mean value of 7.26 kWh/m² in the south.

Concentrating solar thermal energy: Pilot projects for the construction of two solar power plants with a storage total capacity of about 150 MW each will be launched during the 2011 to 2013 period. These will be in addition to the hybrid power plant (solar-gas) project of Hassi R’Mel which was built for 130 MW of gas and 25 MW of thermal solar energy with the parabola system of the giant mirrors on a surface of approximately 180,000 m².

Four solar thermal power plants with a total capacity of about 1,200 MW are to be constructed over the period of 2016 to 2020. The program of 2021to 2030 provides for the installation of an annual capacity of 500 MW until 2023, then 600 MW per year until 2030.

Wind is another renewable source that is very promising with a potential of 35 TWh/year. The wind map of Figure 2, established by the Centre of Renewable Energies Development (CDER) and the Ministry of Energy and Mines (MEM), shows that 50% of the country surface presents a considerable average speed of the wind. The map also shows that the south-western region experiences high wind speeds for a significant fraction of the year. The Algerian RES program plans at first, in the period of 2011 to 2013, the installation of the first wind farm with a power of 10 MW in Adrar. Between 2014 and 2015, two wind farms with a capacity of 20 MW each are to be developed. Studies will be led to detect suitable sites to realize the other projects during the period of 2016 to 2030 for a power of about 1,700 MW.

The Algerian potential of geothermal energy is estimated at 460 GWh/year [7]. More than 200 geothermal sources were counted by the CDER [7] and are recorded, of which one-third of the temperatures are superior to 45°C and where the highest temperatures registered are 98°C and 118°C in Hamam El Maskhoutin and Biskra, respectively, situated in the western part of the country. So far, the applications are limited to agricultural (heating of greenhouses, aquaculture), space heating, sanitary, and balneotherapy.

The overall flows falling over the Algerian territory are important and estimated to be 65 billion m³ but of little benefit to the country due to the following reasons: restrained rainfall days, concentration on limited areas, high evaporation, and quick evacuation to the sea.

Schematically, the surface resources decrease from the North to the South. Currently, the evaluated useful and renewable energies are about 25 billion cubic meters, of which approximately two-thirds is for the surface resources. Hydraulic electricity represented, with 265GWh in 2003, barely 1% of the total electricity production.

The biomass potentially offers great promises with a bearing of 3.7 millions of tons of oil equivalent (TEP) coming from forests and 1.33 million of TEP per year coming from agricultural and urban wastes; however, this potential is not enhanced and consumed yet [2, 6].

Regulations from the MEM which supports the use of biomass from energy crops rapidly caused an increase consumption of biomass, and in the interest in connecting the agriculture and energy sectors, this is seen as a first step in stimulating the use of biomass in Algeria much faster.

MSW is generally defined as waste collected by municipalities or other local authorities. It includes mainly household (domestic waste), commercial, and institutional wastes (generated from shops and institutions). These wastes are generally in solid or semi-solid form. It can be classified as biodegradable waste that includes food and kitchen waste, green waste, and paper (can also be recycled); recyclable materials such as paper, glass, bottles, cans, metals, certain plastics, etc.; inert waste such as construction and demolition wastes, dirt, rocks, and debris; composite waste which includes waste clothing, tetra packs, and waste plastics such as toys; domestic hazardous waste (also called ‘household hazardous waste’); and toxic waste like medication, e-waste, paints, chemicals, light bulbs, fluorescent tubes, spray cans, fertilizer and pesticide containers, batteries, and shoe polish.

According to the National Waste Agency (AND), Algeria produces 10.3 million tons of MSW each year or 28,219 tons per day, with a collection coverage of 85% in urban areas and 60% in rural areas, and a rate of 0.9 kg/inhabitant/day for urban zones and 0.6 kg/inhabitant/day for rural zones. In the capital (Algiers), the production is close to 1.2 kg/inhabitant/day [8].

The composition of MSW is closely related to the level of economic development and lifestyle of the residents. In different districts of the same city, the composition of MSW will be different. In general, the composition of MSW in Algeria with six major categories of waste was identified: organic matter, paper-cardboard, plastics, glass, metals, and others (Table 2).

Organic matter was the predominant category and represented 62% of waste collected. The other categories were represented as follows: paper-cardboard (9%), plastic (12%), glass (1%), metals (2%), and others (14%) (Figure 3). Demolition and construction wastes were not taken into account because they are disposed in uncontrolled open-air sites. The high consumption of fruits and vegetables by the city’s inhabitants could explain the preponderance of organic matter in Algeria’s waste.

According to the National Cadastre for Industrial and Special Wastes prepared in 2007, the overall generation of industrial waste, including non-hazardous and inert industrial waste, is 2,547,000 tons per year with a stock quantity of 4,483,500 tons. This type of waste is generated from the following:

The hazardous waste which includes waste oil, waste solvents, ash, cinder, and other wastes with hazardous nature (such as flammability, explosiveness, and causticity) generated amounts to 325,100 tons/year. The quantities of waste in stock and awaiting a disposal solution amount to 2,008,500 tons, which are generated by four principal sectors: hydrocarbons (34%), chemistry, rubber and plastic (23%), metallurgy (16%), and mines (13%). Compared to textile (4%) as well as paper and cellulose cement and drifts, food and mechanics produce less than 2%.

Table 3 shows that the eastern regions hold the palm for the production of ISW in Algeria, with the wilayas of Annaba and Skikda which are characterized by a high proportion of waste generated and in stock (the petrochemical, transportation, and hydrocarbons industries of these regions). The western region is in the second position, because the industrial area of Arzew is the largest generator of waste with 65,760 T/year only for its refinery, followed by the industrial area of Ghazaouet with 18,500 T/year. The central region is characterized by the high production of lead waste (manufacture of battery and refinery) [11].

These wastes include materials like plastic syringes, animal tissues, bandages, cloths, etc. This type of waste results from the treatment, diagnosis, or immunization of humans and/or animals at hospitals, veterinary and health-related research facilities, and medical laboratories. HW contains infectious waste, toxic chemicals, and heavy metals, and may contain substances that are genotoxic or radioactive. HW reach 125,000 tons/year, of which 53.6% is general waste, 17.6% is infectious waste, 23.2% is toxic waste, and 5.6% is special waste, with waste generation rate 0.7 to 1.22 kg/bed/day, in which 75% to 90% is non-clinical waste and 10% to 25% is clinical waste [13, 14].

Practice of waste management:

In general, elimination is the solution applied to 97% of waste produced in Algeria. Wastes are disposed in open dumps (57%), burned in the open air in public dumps or municipal uncontrolled ones (30%), and controlled dumps and landfill (10%) (Figure 4). On the other side, the quantities destined for recovery are too low: only 2% for recycling and 1% for composting [8].

Open dump mode: In Algeria, the elimination of household and similar wastes through the implementation of open and uncontrolled dumps is the most common mode used, with a rate of 87%. According to an investigation by the Office of Ministry of Land Planning and the Environment, over 3,130 open dumps have been identified in the country with an area of approximately 4,552.5 ha [8]. The majority of these dumps are characterized by almost similar geographical locations. They are located along rivers, roads or agriculture lands. The other common point is that most of these dumps are almost saturated and cannot practically receive waste.

We can use the open dump of Oued Smar (Figure 5) as an actual example; it is located 13 km from the center of Algiers and was established in 1978 on an initial area of 10 ha. It now covers 32 ha and receives more than 700 trucks arriving from 56 municipalities, or 2,200 tons/day of MSW and more than 450 tons/day of rubble and fill. Table 4 provides a summary of the amount of waste placed during the period from 1978 to 2007. It went 15,000 tons during the opening year of discharge to more than 350,000 tons at the end of 2007 [8, 16].

Landfill mode: Since 2001, the Algerian government has chosen to eliminate the municipal solid waste by landfill technique, which is a waste storage underground. One of the objectives of PROGDEM is to abandon the traditional mode of disposing waste by open dumps. Following the launching of PROGDEM, 65 landfills were recorded during the period from 2001 to 2005; 16 were completed, 28 under construction, and 21 during the study phase. In the end of 2007, this number has increased due to the results of pilot projects including that of Ouled Fayet in Algiers (Figure 6). It increased to 80 projects, 20 completed, 34 under construction, and 26 in study, or 15 new projects. First, the wilayas concerned are Skikda, El-Tarf, Annaba, Guelma, Souk Ahras, Batna, Tebessa, Media, Tizi-Ouzou, Setif, Biskra, Algiers, M’Sila, Ouargla, Blida, Djelfa, Jijel, Bejaia, and Chelf. In 2010, this number increased to 100 landfills, much of which was nearly completed, according to a communication of same source.

However, this technology also has several disadvantages such as landfills requiring a large surface area and pollution problems, including ground water pollution, air pollution, and soil contamination.

The landfill of Ouled Fayet is part of the new policy of integrated waste management which included the transformation of some dumps into landfills. It serves over 34 towns of the wilayas of Algiers and Tipaza. The amount of landfill waste is 864 tons/day in 2005 against 72 tons/day when it opened in 2001. Table 5 shows the evolution of the amount of landfill waste since October 22, 2002.

We can give the example of composting station in the city of Blida; this station was put into service in 1989 and rehabilitated during the period from 1992 to 1996 and returned to service in 1996. It spreads over an area of 3.7 ha for a nominal capacity of 100 tons per shift for 8 h and for a production of 40 tons of compost.

Recovery and recycling mode: Depending on the services of the MATE, Algeria has the ability to recover an amount of waste estimated at 760,000 tons/year (Table 6), in which paper is the essential part in the possibility of recovery and recycling with a quantity of 385,000 tons/year. There are over 2 million tons of plastic packaging products in Algeria by 192 units, but only 4,000 tons are recovered (0.0002%).

Knowledge of the physicochemical parameters of MSW allows the evaluation of the potentially harmful risks of pollution on the environment and human health. Also, it allows the determination of the best ways for the valorization of waste. The most important conditioning parameters for valorization are listed in the following sections [17, 18].

From previous studies which were carried out by Tabet [3], Guermoud [19], and Loudjani [9] show the values of physicochemical parameters as shown in Table 7.

Energy from waste is not a new concept, but it is a field which requires a serious attention. There are various energy conversion technologies available to get energy from solid waste, but the selection is based on the physicochemical properties of the waste, the type and quantity of waste feedstock, and the desired form of energy. Conversion of solid waste to energy is undertaken using three main process technologies: thermochemical, biochemical, and mechanical extraction [20].

Biochemical conversion: Biochemical conversion processes make use of the enzymes of bacteria and other microorganisms to breakdown biomass. Biochemical conversion is one of the few which provide environment friendly direction for obtaining energy fuel from MSW. In most of the cases, microorganisms are used to perform the conversion process: anaerobic digestion and fermentation.

Thermochemical conversion: Thermal conversion is the component of a number of the integrated waste management solutions proposed in the various strategies. Four main conversion technologies have emerged for treating dry and solid waste: combustion (to immediately release its thermal energy), gasification, pyrolysis, and liquefaction (to produce an intermediate liquid or gaseous energy carrier).

The kind of energy produced from the biogas depends directly on the needs of the buyer, and there are three different forms: electricity generation, heat and steam generation, and transportation fuel [21].

Electricity generation: This is the most common form of energy produced in facilities constructed today.

In Algeria, a little interest was given to this technology despite the important resources and the successful applications that have been made by the National Institute of Agronomy (El Harrach) and the CDER through the establishment of two experimental plants in Bechar and Ben Aknoun for the study of biogas production from cow dung. However, we must note the efforts of the Algerian government in these last years to develop this technology by upgrading the landfill of Ouled Fayet which has been put into operation in 2011. The project’s main objective is the capture of the landfill’s gas which contains 50% of methane (CH₄); the expected amount of emission reduction is 83,000 T equivalent CO₂/year [22].

In addition to biomass, power projects are at the feasibility study stage such as the Sonelgaz’s biomass power project in the Oued Smar site, which has an installed capacity of 2 MW that can reach a peak of 6 MW from the discharge of this site, and the energy recovery plant of biogas generated in the landfill of Batna [12].

Landfills require large amounts of land that could be used for other purposes; incineration of solid waste can generate energy while reducing the volume of waste by up to 90%.

With advanced technologies, waste can be used to generate fuel that does not require mining or drilling for increasingly scarce and expensive non-renewable fossil-fuel resources.

Using waste as a feedstock for energy production reduces the pollution caused by burning fossil fuels. While traditional incineration still produces CO₂ and pollutants, advanced methods such as gasification, pyrolysis, and liquefaction, have the potential to provide a double benefit: reduced CO₂ emissions compared with incineration or coal plants, and reduced methane emissions from landfills.

The WTE technology has significantly advanced with the implementation of the Clean Air Act, dramatically reducing all emissions.

Many waste-to-energy technologies are designed to handle only one or a few types of waste (biomass, solid waste or others). However, it is often impossible to fully separate different types of waste or to determine the exact composition of a waste source. For many, waste-to-energy technologies to be successful, they will also have to become more versatile or be supplemented by material handling and sorting systems.

The gas generated by processes like pyrolysis and thermal gasification must be cleaned of tars and particulates in order to produce clean and efficient fuel gas.

Some waste-to-energy pilot plants, particularly those using energy-intensive techniques like plasma, have functioned with low efficiency or actually consumed more energy than they were able to produce.

Toxic materials include trace metals such as lead, cadmium and mercury, and trace organics, such as dioxins and furans. Such toxins pose an environmental problem if they are released into the air with plant emissions or if they are dispersed in the soil, allowed to migrate into ground water supplies, and work their way into the food chain. The control of such toxins and air pollution is the key feature of environmental regulations governing MSW-fueled electric generation.

The regulatory climate for waste-to-energy technologies can be extremely complex. At one end, regulations may prohibit a particular method, typically incineration, due to air-quality concerns, or classify ash byproducts of waste-to-energy technologies as hazardous materials. At the other end, while changes in the power industry have allowed small producers to compete with established power utilities in many areas, the electrical grid is still protected by yet more regulations, presenting obstacles to would-be waste-energy producers.

Waste-to-energy systems are often quite expensive to install. Despite the financial benefits they promise due to reductions in waste and production of energy, assembling the financing packages for installations is a major hurdle, particularly for new technologies that are not widely established in the market.