Pyrolysis/ Gasification

Introduction

Pyrolysis is a process of chemical decomposition of organic matter brought about by heat. In this process, the organic material is heated in absence of air unit the molecules thermally break down to become a gas comprising smaller molecules (known collectively as syngas). Gasification can also take place as a result of partial combustion of organic matter in presence of a restricted quantity of oxygen or air. The gas so produced is known as producer gas. The gases produced by pyrolysis mainly comprise carbon monoxide (25%), hydrogen and hydrocarbons (15%), and carbon dioxide and nitrogen (60%). The next step is to 'clean' the syngas or producer gas. Thereafter, the gas is burned in internal combustion (IC) engine generator sets or turbines to produce electricity.

Advantages

The major advantages of setting up of waste-to-energy projects are:

• The quantity of waste gets reduced by nearly 60% to 90%, depending upon the waste composition and the technology adopted
  
• Demand for land, which is already scarce in cities, for land filling is reduced;
  
• The cost of transportation of waste to far-away landfill sites gets reduced; and
  
• There is net reduction in environmental pollution
  
• Apart from generating power from the waste, the slurry produced from biomethanation technology acts as a good fertilizer
  

Limitations/ Constraints

The growth of this sector has been affected on account of the following limitations/ constraints:

• Waste-to-Energy is still a new concept in the country;
• Most of the proven and commercial technologies in respect of urban wastes are required to be imported;
• The costs of the projects especially based on biomethanation technology are high as critical equipment for a project is required to be imported.
• In view of low level of compliance of MSW Rules 2000 by the Municipal Corporations/ Urban Local Bodies, segregated municipal solid waste is generally not available at the plant site, which may lead to non-availability of waste-to-energy plants.
• Lack of financial resources with Municipal Corporations/Urban Local Bodies.
  
• Lack of conducive Policy Guidelines from State Govts. in respect of allotment of land, supply of garbage and power purchase / evacuation facilities.
  

Financial Support

The scheme for providing financial support for waste-to-energy projects is presently under review and accelerated programme on energy recovery from municipal and industrial wastes is being development for providing a major fillip to this sector.

Implementation

Waste-to-energy projects can be set up municipal corporations, other urban local bodies, government institutions, and private developers having technical and managerial capabilities for implementing such projects on the basis of Build, Own, and Operate (BOO); Build, Own, Operate, and Transfer (BOOT); Build, Operate, and Transfer (BOT); and Build, Operate, Lease, and Transfer (BOLT). The proposals are to be sent to the MNES after completing all tie-ups for waste procurement, sale and evacuation of power, pollution control, etc. In cases where debt financing is involved, IREDA, other financial institutions, and commercial banks are required to forward proposals alone with their Appraisal Note. An advance copy of the proposal may be sent to the MNES.

Cost: Gasification/pyrolysis 8-9

Potential

There exists a potential for generating an estimated 1700 MW of power from the urban and municipal waste, and about 1000 MW from industrial wastes in the country. The potential is likely to increase further with economic development.

Achievements

A total of 27 waste-to-energy projects have been completed as on 31 March 2005 in India, with an aggregated installed capacity of 45.50 MW. In table gives the state-wise cumulative achievements as on 31 March 2005.

Cumulative achievements as on 31 March 2005

Main Application: Energy Recovery from Wastes

Contact:

Ministry of Non-Conventonal Energy Sources,
Govt. of India
Block-14, CGO Complex, Lodi Road
New Delhi – 110 003
Tel: 91 11 2436 0707/ 2436 0404
Fax: 91 11 2436 1298