Waste to Energy Integrated with Desalination

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Preamble

The two major challenges plaguing the modern coastal cities worldwide  are waste management and water scarcity. On one hand the ever increasing waste production driven by various factors such as the increased consumption, growing population and aspirations for better standard of living has choked current day waste management system. On the other hand the availability of  clean and affordable water has become a question across many cities. Catering to the twin problem aessoft India leveraging its experience has developed an integrative approach to empower smart cities to no only solve the issue rather make it a sustainable solution promoting the circular economy. 

Electricity has become the fundamental driving unit for any activity in the current day scenario.  While the world is hungry for power, the supply inadequacy and stability are still the most gnawing problem. Worse, the consumable water – another important resource that drives the whole living and ecosystem, is depreciating in its availability. The twin shortages cannot be overlooked for long.

Paradoxically, what is available in abundance in today’s world is consumption garbage or waste. Every country produces garbage in growing volume. Global annual waste generation is expected to have a whopping 70% increase from 2.01 billion tonnes in 2016 to 3.4 billion tonnes by 2050. (Source: What a Waste 2.0, Silpa Kaza, Perinaz Bhada-Tata, Frank Van Woerdern, World Bank Group).

 Since every material has a preset calorific value, the municipal solid waste too has a considerable degree of high carbon and organic content left in it.  Clearly, the waste has huge potential that hasn’t been harnessed for its large heat value. For instance, it is estimated that Chennai  – one of the top four metros of India and a population of over seven million people, produces municipal waste of 5000 metric tons per day (http://www.chennaicorporation.gov.in/departments/solid-waste-management/index.htm#solid). The storing capacity of two major waste deposition areas Perungudi, Kodungaiyur in Chennai have maxed out. Chennai has not much land left to store new waste dump yards.  This has raised a lot of questions and concerns on how to dispose of the waste. It is been projected that by 2047 around 1,400 sq.km of landfill area will be needed for dumping the municipal solid waste which is equivalent to a combined area of three of most populous cities in India in landmass: Hyderabad, Mumbai & Chennai (Sustainable Solid Waste Management in India 2012 , Ranjith Kharvel & Annepu).

Exhibit 1:  Municipal solid waste generation of various Indian cities in 2016. (Solid Waste Management in India, Utkarsh Patel, ICRIER, New Delhi)

Water scarcity or shortage, as mentioned before,  is the second most pressing hurdle for a developing country. As per a study conducted by Niti Aayog (formerly Planning Commission of India), the demand will exceed supply by a factor of two by 2030. The projections show, 6% of GDP will be lost by 2050 due to water crisis. (Composite Water Management Index, NITI Aayog, August 2019 ). Presently, about one-third of the world population of 6.8 billion lives in water-scarce areas. Analysts estimate that by 2025, about half of the world population will have to live  in water-scarce areas (Report, World Health Organization).  Solutions such as water transfer or dam construction are helpful but inadequate, making water shortage as critical as climate change. 

Exhibit 3: Supply and demand projections of water in BCM(2008,2030) in India. (Composite Water Management Index, NITI Aayog, August 2019 ).

Similar to municipal solid waste, seawater too is available in abundance. A possible solution, therefore, is to explore technology that transforms what is wasteful but available in abundance to produce into what is essential but in short supply. In our context, we need a technology that uses waste as a fuel to produce power and replace or reduce the use of conventional fossil fuels such as coal that anyways pollutes the environment.

The technology group that uses waste as fuel to generate steam and produce power electricity is known as waste to energy or WTE technologies. The technology hugely helps to empty the wasteland and produce power. Thus, WTE technologies provide a solution to our first order crisis- the energy inadequacy to satisfy the power demand. Recently, innovations are underway testing possibility that the hitherto only waste to energy (WTE) technologies also work to purify seawater and produce potable water at the same plant concurrently.

The remaining part of the research paper documents this technological breakthrough, key elements and analyses the financial and managerial considerations while implementing the augmented innovation.

An Augmented Innovation

Exhibit  4: Map Integrating Waste to Energy and water desalination 

Waste To Energy

Waste to energy has been a successful model in promoting circular economy of the country by providing value to waste. 

The process begins with the collection of waste all over a city and transporting it to specially created waste dumps. Once there, the waste of all types is collectively taken to an incineration chamber where they are completely burnt. This fires up the boiler where water is used as the fluid of the system. Exhibit 4 below maps the dynamic technological innovation that integrates energy production from waste to a simultaneous purification of seawater into potable water. In a conventional power plant, the heat energy so produced converts water into steam which is sent to a turbine. After the low-pressure steam is released from the turbine in the proposed twin technology contribution, the steam at the outlet is equally partitioned and diverted to a condenser and a de-aerator. At the condenser, the cooling seawater is brought around 303k. Due to the heat absorbed from the steam, the seawater outlets temperature raises to 313k. Now at the de-aerator, the exhaust steam is de-aerated and along with the condensed water is pumped back to the boiler. The flue gas obtained is sent to baghouse filters and electrostatic precipitators (ESP). This results in the conversions of a very large pile of waste into ash and dust particles that get accumulated in the baghouse filters. The waste is thus reduced to only 5% of the previous volume as a result of this process and hazardous solid wastes are converted into non-hazardous particles. Furthermore, this results in a cleaner flue gas too. Since the steam passes through the turbine, a fall in the temperature and pressure occurs. The residue of the bottom ash that remains after the combustion is processed through toxin destructive conveyor to make it non-hazardous and can now be safely put into landfills or recycled as construction aggregate. Meanwhile, the power generated from the turbine shaft is used up to generate electricity that is sent to power sub-stations. This is distributed to the locations nearby through power grids.

An ideal solution for coastal cities

There are several water stressed cities across the globe. Though there several standalone desalination technologies available the investment intensive nature of such projects have posed a  challenge for adoption. But  the Integration of MED or LTTD have the potential to navigate the same

The Indian Scenario

India is among the top two populous countries in the world with 1.35 billion people. It generates an enormous amount of garbage with a daily per capita generation of municipal solid waste in India ranging from about 100 grams in small towns to 500 grams in large towns (Source: India 2025- Environment, Shaheen Singhal, Planning Commission, Government of India), totaling close to 300 million tons of municipal solid waste annually. With the rapid transformation and fierce consumerism, the waste generation is feared to multiply several times and will severely test an already strained waste management system in India. Added to this, India faces water shortages in general and has experienced the biggest water crisis in the current year of 2019. The country is thus, urgently seeking solutions on how to enhance water availability. The policy research paper suggests an innovative technology solution to produce power from waste and integrate the process technology to desalinate seawater and make it potable water concurrently. The research paper describes the innovation, technology and mechanics of the integrated technology founded on detailed evaluation and feasibility study for Chennai. The city is one of the four top metro cities of India and faces the double whammy of growing garbage and declining potable water supply. It reports empirical data and the functioning of a full-scale implementation of WtE technology in Jabalpur(smart City), Madya Pradesh. The twin technology solution, however, faces a full-scale suite of managerial and policy challenges threatening to restrict the adoption and diffusion so necessary for urban and metro smart cities in India. The research paper, therefore, concludes with a ten-point policy reform agenda.

Feasibility Study For Chennai

Exhibit 5(a) : Physical composition of the waste substances. (Greater Chennai Corporation Report, 2019) 

Exhibit 5(b) : Chemical composition of the waste substances. (Greater Chennai Corporation Report, 2019)

Exhibit 5(c) : Sources and categories of the waste generation. (Greater Chennai Corporation Report, 2019)

The Implementation validated that the integrated
technology yields a host of managerial and organizational benefits some of them
are listed below.

· Circular economy- the complete utilization of waste promotes a circular economy in the country.

· Ease of Operation- This will increase the efficiency of the operation of this plant as waste availability won’t be an issue for power generation.

· Development of water and energy security in the nation – If more plants of this technology, are set up, it multiplies the twin benefits of reducing water sacristy and usage of coal.
· Increase the viability of the waste to energy power plants in India – Implementations of these policies will promote the waste to energy business in India.  

Furthermore, the payback period for the above estimation is 2.11 years with a plant life of 25 years. It is evident from the insights generated from the calculation that the twin technology could have a major contribution in terms of potable water generation and the waste elimination while generating a nominal amount of energy production. Hence the implementation of such integrated solution would be advantageous in a smart city as this would create a circular economy in which sustainability and self-sustenance is ensured. 

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