Courtesy: The Centre for Public Policy Alternatives (CPPA)
The amount of waste we make every single day in our homes, offices and other such places is increasing exponentially due to galloping global population. Generally, the higher the economic development, rate of population and urbanization, the greater the amount of solid waste produced. The probability of that waste ending up in landfill is quite high because, landfilling is still the predominant waste disposal method worldwide. In those landfills, probably none of the valuable material in the waste would be recovered, and most of the present day landfills even don’t have; biogas capture system, protective liner to stop leachate from contaminating fresh water. These practices negatively affect climate change and waste precious natural resources. Moreover, the thing, which is making the situation, even worse is the throwaway culture in our society. Once the waste is removed from our sight, we never bother to think about it. This mindset need to be changed because we can’t afford to let that waste sitting in some landfill and doing nothing for us but hurting our health and our environment. While we can make use of this exponentially increasing amount of waste in number of ways.
One of the promising way of handling waste is converting it into energy and significantly reducing the amount of waste ending up in landfills. There are number of thermal treatments, like combustion, pyrolysis or gasification for converting the waste into energy. But gasification has some fundamental advantages over other thermal treatments.
Gasification is the incomplete oxidation process which breaks carbon based organic fraction of the waste into a synthesis gas, syngas that is a mixture of CO and H2, by carefully controlling the amount of oxidizing agent present. Oxidizing agent plays very important role in creating the reaction environment suitable for performing the gasification reactions breaking complex compounds into simple molecules such as CO and H2 forming syngas. The major oxidizing agents gasification processes are air, oxygen, steam, and CO2 etc. Depending on the situation and project requirements appropriate oxidizing agents is selected. The aspect that mainly characterizes and distinguishes Gasification of waste in relation to combustion is the high flexibility both on fuel in input and on the type of products obtained.
Plasma Gasification is one of the emerging gasification processes, which earlier was just used for the destruction of the hazardous waste, but later the process was used for the recovery of energy out of all kinds of feedstocks. The fundamental advantage of plasma gasification over other thermal treatments is the extremely high temperatures, which breaks down any complex compounds into its most basic elemental forms in an incomplete oxidation environment, which later could be recombined in desired proportions to get the desired product. When waste is processed as a feedstock in a plasma gasification plants, the organic fraction of the waste is converted into high quality syngas that can be used for chemical production or as fuel for electricity generation. The inorganic fraction of the waste is vitrified into non-leachable slag that can be disposed of safely into landfills, recycled, or reused as construction material.
Plasma Gasification has the potential to be the next generation of waste-to-energy solutions because Plasma gasification can process all kind of wastes by adjusting the energy input with the plasma, independently of the oxidizing agent ratio, the LHV and the moisture of the waste. Higher temperatures involved in Plasma gasification produce good quality syngas by thermal cracking of impurities and creating highly active radicals, electrons, ions and excited molecules in the gas streams, significantly improving the net electrical efficiency of the system.
One of the main hurdles limiting the deployment of plasma gasification on large scales is high electric power requirement of the plasma torch. Designing an energy efficient plasma gasification system that provides optimal conversion and operating conditions will definitely accelerate deployment of Plasma Gasification technology as an effective waste-to-energy solution worldwide in future.
Full development of plasma gasification technology has the potential to significantly mitigate following main challenges of 21st century:
Global Waste generation
Power requirements
Climate change
We need more public and political awareness relating environmental issues in order to push governments/stakeholders to plan to implement strategies for waste management. Proper waste management is one of the most important environmental challenges of modern society.
References
Frédéric Fabry et al. Waste Gasification by Thermal Plasma: A Review. Waste and Biomass Valorization, Springer, VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS, 2013, 4 (3), pp.421-439.
Arnar S. Valmundsson, “Plasma Gasification Process Modelling and Energy Recovery From Solid Waste”, 5th International Conference on Energy Sustainability (U.S.A.), 2011.
EFW Technology Overview, The Regional Municipality of Halton, Submitted by Genivar, URS, Ramboll, Jacques Whitford & Deloitte, Ontario, Canada, May 30, 2007.
M. Rajasekhar, “Energy Generation from Municipal Solid Waste by InnovativeTechnologies – Plasma Gasification”, second International Conference on Nanomaterials and Technologies (CNT 2014).
Alter NRG Plasma Gasification is the next generation of waste-to-energy solutions. Retrieved from http://www.alternrg.com/waste_to_energy/.
Caroline Ducharme, Technical and economic analysis of Plasma-assisted Waste-to-Energy processes, Retrieved from Earth Engineering Center, Columbia University, September 2010.
Company Overview of Alter NRG Corp. Retrieved from https://www.bloomberg.com/research/stocks/private/snapshot.asp?privcapId=328802