Waste-to-energy nexus: An overview of technologies and implementation for sustainable development

Energy acts as a driver for the globe. It is a factor of production. Thus, it acts as a nexus for sustainable development. The energy requirements are fulfilled through various energy sources like coal, natural gas, etc. 

Keywords: energy, MSW, Waste-to-Energy, Thermochemical, Biochemical, Incineration,  Pyrolysis, Gasification, Anaerobic digestion, Landfilling                    
 

Over the past years, the population has experienced rapid growth. This also increased energy demands. But, these fossil fuels have limited reserves and in the coming years, they will not be able to fulfill the energy needs.

As the population is increasing, Municipal solid waste(MSW) has also experienced steady growth. It is referred to as non-hazardous garbage which is produced from domestic, commercial, and industrial activities. It consists of various biodegradable and recyclable materials. According to the report published by World Bank, the global MSW generation in 2018 was approximately 2.01 billion tonnes.

The energy in the MSW can be extracted through Waste-to-Energy(WtE) technologies. There are significant steps have been taken to incorporate WtE technologies as a part of Waste Management. There are two main processes of WtE technologies:

1. Thermochemical

2. Biochemical

1. Thermochemical conversion:

In this process, carbonaceous organic matter is decomposed under high temperatures to produce heat energy, fuel oil, or gas. The technological options under this process include:

1). Incineration:

In this method, MSW is directly burnt in an excess oxygen supply in a furnace, temperature range of 800⁰ C - 1000⁰ C. It leads to the production of heat and ash. This method helps in reducing the land space needed for landfilling by reducing the mass of waste by 70-80% and reducing the volume by 80-90%.

2). Pyrolysis:

Pyrolysis involves the decomposition of MSW in a space that is deficient in oxygen. The temperature range is high i.e. 300 - 900⁰ C. It leads to the production of different forms of energy carriers such as char, pyrolysis oil, and combustible gases.

3). Gasification:

Gasification is an advanced thermal treatment process. It involves the decomposition of MSW at a high-temperature range of 550-1600⁰ C in a controlled supply of oxidant.

 2.  Biochemical conversion:

            It involves the decomposition of the biodegradable organic compound under the influence of bacteria. The microbial action can either take place in the presence of oxygen or in the absence of oxygen. The main technological pathways are:

1). Anaerobic digestion

2). Landfilling                    

Selection of WtE technology w.r.t an area depends on various factors such as technical, economic, environmental, and social. The criteria for consideration include waste composition and characteristics, land area requirement, capital, technological complexity coupled with labor skills requirements, and geographical locations.

Sustainable development means satisfying the present needs without damaging that of future generations. Production of energy from WtE will create more job opportunities and stimulate economic growth. According to a previous study, a WtE plant can employ over 100 people. WtE technologies have been recognized as clean energy technologies. They have the capability of ensuring a clean society and fostering energy security. They ensure adequate treatment of the effluent for a cleaner environment. It ensures the production of renewable and sustainable energy along with achieving a circular economy. It has also proved to be positive in terms of reduction in Global warming.