Waste to Electrcity: Some Technical Solutions

The Indian economy faces significant challenges in terms of meeting its energy needs in coming decade. There is an increase in energy requirement but there is slower than expected increase in domestic fuel production. Thus, there has been increased importance of energy mix.

Coal continues to remain the dominant fuel in total production (65%). There is 75% electrification in India. This means, one-fourth of Indian population still lacks access to electricity.

Renewable Energy

[] India is the first country to have a Ministry of non-conventional energy resources in early 1980s

[] India’s cumulative grid interactive has reached 33.8GW. 66% is from wind energy and solar PV contributed nearly 4.59% along with biomass and small hydro projects.

Waste to Energy (WtE)

[] Every year, 55mt of municipal solid waste and 38 billion litres of sewage are generated in urban areas.

[] Waste generation is expected to increase rapidly in future at per capita rate of approx. 1-1.33% annually

[] India has long involvement with anaerobic digestion and biogas technologies

[] Waste water treatment plants have been established which produce renewable energy from sewage gas.

Types of waste

[] Urban waste

[] Industrial waste

[] Biomass waste

[] Biomedical waste

Importance of WtE

[] Problems caused by solid and liquid waste can be mitigated by adoption of environment friendly waste to energy technologies that will allow treatment and processing of waste before their disposal.

[] Environmental benefits will be less land, air and water pollution.

[] It generates clean, reliable and renewable fuel source thus, reducing dependence on fossil fuels

[] Monetary benefits- government incentives, right technology will enhance acceptability, more research in getting energy from sewage waste, industrial waste and hazardous waste. Expansion possibilities if they become successful

Energy from Waste-Technologies

Thermal conversion

> Involves thermal degradation of waste under high temperature

> Complete oxidation of waste occurs at high temperature

> Technology: Incineration

> But, it is losing attention because of emission characteristics

Thermo-chemical conversion

> Involves high temperature driven decomposition of organic matter to produce heat/energy/fuel/gas

> Useful for wastes that contain high percentage of organic non-biodegradable matter and low moisture content

> Technology: Pyrolysis and gasification

> The products of these processes can be used purely as heat energy or further processed chemically, to produce a range of end products

Bio-chemical conversion

> Involves enzymatic decomposition of organic matter by microbial action to produce methane gas and alcohol etc.

> Used for wastes having high percentage of organic biodegradable matter high level moisture/water content

> Technology: Anaerobic digestion (biomethanation) and fermentation

Electrochemical conversion

> Refers to microbial fuel cells

> System is developed to trap energy from wastes where reduction-oxidation machinery of immobilised microbial cells is catalytically exploited for accelerated transfer of electrons from organic wastes to generate electricity and bio-hydrogen gas

Constraints

[] WtE still a new concept

[] Most proven and commercial technologies are imported

[] Cost of projects are high, especially projects like biomethanation which is exclusively imported

[] Low level of compliance to MSW rules, thus, segregated solid waste is generally not available at plant sites.

[] Lack of financial resources with urban bodies/municipal corporations

[] Lack of conducive policy guidelines from central and state governments

Support of Indian government

[] Recognised waste to energy as renewable technology and supports through varioussubsidies and incentives

[] The Ministry of New and Renewable Energy actively promoting all technology options available for energy recovery from urban and industrial wastes

[] Promoting research, providing financial support for R&D projects on cost-sharing basis. Key stats such as value of recyclables, amount of environmental pollution from waste resources and quantity of industrial waste generated need to be computed to gain better understanding.

[] Solid waste management is as crucial component of Swachh Bharat Mission