The Complete Guide: Waste to Energy and How it is Helping Cities Become More Sustainable

As cities and towns continue to grow and industrialize, the amount of trash generated continues to increase. It’s no secret that this is one of the greatest threats to our environment. Fortunately, we have found ways to utilize waste and generate energy from unlikely sources with minimal impact on the world around us. 

In this article, I discussed Waste-to-Energy (WTE) as a solution for all types of waste, including household and municipal solid waste, organic waste, and industrial waste, and it covers the following subtopics:

• What is Waste to Energy?
• Types of Waste
• Process of Generating Energy
• Technologies Available
• Benefits of Waste to Energy
• Potential to Generate Energy

Waste to Energy is a process that converts waste to produce energy.

The Waste-to-Energy process is a thermochemical conversion of organic wastes, such as municipal solid waste or biodegradable agricultural wastes, into renewable energy and other useful products. The process generates electricity, heat, and/or steam for use in cogeneration or to power other electrical devices.

According to NASA scientists, landfills are major sources of methane, a greenhouse gas that is 84 times more dangerous than carbon dioxide. Waste-to-Energy incineration is an environmentally friendly alternative to landfills for waste disposal, and it has numerous other advantages. This is the primary driver of the expected growth of the global waste-to-energy market in the coming years.

There are different types of waste that are generated from our daily or industrial activities such as organic waste, e-waste, hazardous waste, inert waste, etc.

All organic wastes are essentially carbon-based compounds, even if they vary in nature and degrade at different rates. The organic fraction of waste is further subdivided into non-biodegradable organic waste and biodegradable organic waste. 

1. Biodegradable waste is made up of organics that can be used as food by naturally occurring microorganisms in a reasonable amount of time. It comprises agro residue, food processing rejections, municipal solid waste (food waste, leaves from garden waste, paper, cloths/ rags, etc.). waste from poultry farms, cattle farm slaughterhouses, dairy, sugar, distillery, paper, oil extraction plant, starch processing, and leather industries.
2. Non-biodegradable waste is organic materials that are resistant to biological degradation or degrade at a very slow rate. This primarily consists of woody plants, cardboard, cartons, containers, wrappings, pouches, discarded clothing, wooden furniture, agricultural dry waste, bagasse, rice husk, and other similar materials.

The use of “municipal solid waste” (MSW) as a fuel source can be used to generate electricity. MSW power plants, also known as waste to energy (WTE) plants, are intended to dispose of MSW while also producing electricity as a byproduct of incinerator operation.

Mass Burn is the most widely used waste-to-energy technology, in which MSW has directly combusted in the same way that fossil fuels are in other direct combustion technologies. When MSW is burned, it converts water to steam, which drives a turbine connected to an electricity generator.

In a mass-burn waste-to-energy plant, electricity is generated in the following seven stages:

Waste to Energy (WTE) refers to a range of technologies that convert municipal solid waste (MSW) into electricity, heat, and fuel. The technologies used in this process include thermal treatment, gasification, pyrolysis, and anaerobic digestion. These processes may also be used to generate energy from other waste products such as industrial waste. Let us understand these processes:

1. Biomethanation: It is a process in which organic material is converted directly into biogas. The process takes place within an anaerobic microbial environment and results in biogas containing mostly methane (~60%), carbon dioxide (~40%), and other gases. Biomethanation has dual benefits: it gives biogas as well as manure-enriched wastewater called Digestate.
2. Incineration: It is the complete combustion of trash (Municipal solid waste or Refuse produced fuel) with heat recovery to produce steam, which is then used to generate electricity via steam turbines. A sophisticated air pollution control system is required to handle the flue gases produced by these boilers. After proper processing, the ash from solid waste incineration can be used as construction material, while the rest can be safely disposed of in a landfill.
3. Gasification: It is a decomposition process that uses high temperatures (500-1800o C) and a small amount of oxygen to produce synthetic gas (a combination of carbon monoxide) and hydrogen. This gas can also be used for heating and power generation. The goal of waste gasification is to generate power more effectively at a lower power level (less than 2MW) while also reducing emissions, making it a viable option for solid waste thermal treatment.
4. Pyrolysis: It is a process that employs heat to break down combustible materials in the absence of oxygen, resulting in a mixture of flammable gases (mainly methane, complex hydrocarbons, hydrogen, and carbon monoxide) as well as liquids and leftovers. The gas produced by either of these processes can either be utilized to heat boilers or cleaned up and used in combustion turbine generators. The goal of this procedure is to reduce emissions while increasing gain.

1. Reduces Landfill Waste

Converting waste to energy helps to reduce the amount of waste that ends up in landfills. Reduced waste means fewer landfills and lower greenhouse gas emissions.

2. A Significant Amount of Energy is Produced

One tonne of waste can produce 550 to 700-kilowatt hours, which is enough to meet the electricity needs of one home for a month.

3. Aids in the Reprocessing of Excess Waste

Another advantage of waste-to-energy technology is that it reprocesses any excess metals or remains, such as aluminum and steel, reducing the amount of waste material even further.

4. Green and Sustainable Method

The technology’s process is green and eco-friendly in and of itself. It uses cutting-edge pollution control equipment to brush and filter carbon emissions, limiting their release into the environment.

The following is a summary of the sector-by-sector analysis of India’s energy potential, focusing on the urban and industrial sectors:

In India, the overall energy-generating potential from urban and industrial organic waste is estimated to be around 5690 MW. This is a lot of power! However, it is not being utilized.

And this needs to change. WTE plants drastically reduce the waste volume in the most environmentally friendly way possible, reducing the need for landfills.

Garbage is used very efficiently, and much-needed electricity is generated, bridging the electricity gap. It is the right time for all cities to pay attention to this source of power as a cost-effective way to address city waste.

The government has also set up a National Solid Waste Management Programme (NSWMP) with the aim that total waste generated in the country will be recycled or processed for renewable energy.

With over 22 years of experience in water and wastewater treatment systems, Aquamech has strived to be at the forefront of new technology adaptation.

Contact our design head Navdeep Singh Sethi to learn more about our Advanced Integrated Process for Energy Recovery through Integration of Waste Water and Organic Solid Waste.