• Electrical India
  • Nov 5, 2015

Electricity
From Garbage

Shadnagar facility of 6MW in Andhra Pradesh is the first operational Waste-To-Energy (WTE) plant in India. Selco has a 20 year PPA with APTRANSCO at ` 3.48/kWh and connects to the grid through a 33/11kV substation...

- R P Deshpande


 All cities anywhere have garbage disposal as a major problem. It is produced in large quantities, and has nowhere to go, except mostly in landfills. This is attracting attention of city planners lately and measures are being considered towards making the garbage disposal fruitful and productive. One of the major areas of interest is the use of garbage for energy. Wastes produced in Indian cities is quite huge, as can be seen from the next table:

Waste generated in urban India every year

  • Solid waste : 300 Million Tons
  • Liquid waste: 4400 Cu. Metres.
  • Municipal solid waste: 0.30 – 0.66 Kg / person / day
  • Plus industrial waste.

  Urban Local Bodies spend around ` 500/- to ` 1500/- per ton on solid waste management, out of which 60 to 70% of the amount is on collection, 20 to 30% on transportation, while hardly any fund is spent on treatment and disposal of waste. Even after segregation of waste, about 45% goes to landfills.

  Most solid waste goes to landfills/water bodies, causing serious pollution with methane and CO². Finding new landfill sites is no solution. Permanent and eco-friendly solution lies in gainful utilisation of this garbage into energy, by processing and treating the waste before final disposal. This can reduce the waste by up to 90%, and at the same time, recover fuel gas for cooking and lighting and electricity.

  Waste-to-energy conversion is possible in a number of ways. Refuse-Derived Fuel (RDF) facilities process the MSW prior to direct combustion. The level of pre-combustion processing varies among facilities, but generally involves shredding of the MSW, and removal of metals and other bulky items. Energy from municipal waste takes care of two problems- garbage and energy needs, at the same time. There is no pollutant released or carbon emissions to speed up global warming, and waste to energy plants can be very cost efficient. Municipal solid waste pays not only in collection fees but also in the production of by-products which can be sold for a profit. It will not be out of place to mention here that landfill is banned in Germany, and entire garbage is usefully employed.

  Biomass is a clean source of energy in Brazil. Over 1 million people work in production of biomass, which represents 27% of the country’s energy generation. Nearly all of the biomass for power generation is based on the use of waste and residue fuels.

  India is second in rank in the world in biomass utilisation (MNRE). Biomass can be tapped right at the landfill. When garbage decomposes, it gives off methane gas. Natural gas is made up of methane. Pipelines are put into the landfills and the methane gas is collected. It is then used in power plants to make electricity. This is called landfill gas.

Waste to energy cycle...

  Landfill gas is gathered from landfills through extraction wells placed depending on the size of the landfill. Roughly one well per acre is typical. Gas is then used to produce electricity, heat, fuels and chemical compounds.

  Today, more than 900 thermal WTE plants operate around the globe. These plants treat an estimated 200 million tons of Municipal Solid Waste (MSW) with an estimated output of 130 terawatt hours (TWh) of electricity. Vancouver landfill is operative since 1966, and in 2003 received 450,000 tons of MSW. The landfill serves over 900,000 residents and businesses from city and surrounding area. The landfill is part of the district's disposal system consisting of two landfills and a WTE facility that collectively serve 2,000,000 people. The project results in the recovery of approximately 500,000 GJ/year of energy, the total energy requirements of 3,000 to 4,000 homes, and results in a reduction of more than 230,000 tons per year CO2 (the emissions of approximately 45,000 automobiles).

Landfill gas to energy systems...

  Shadnagar facility of 6MW in Andhra Pradesh is the first operational waste-to-energy (WTE) plant in India. Selco has a 20 year PPA with APTRANSCO at ` 3.48/kWh and connects to the grid through a 33/11kV substation. The plant went commercial in Nov 2003. There are some other plants working in India for WTE conversion.

  Municipal and industrial garbage incinerating plants near housing colonies in Europe are so clean that many times more dioxin is now released from home fireplaces and backyard barbecues than from such incinerators. Today's waste-to-energy plants have arrays of newly developed filters and scrubbers to capture the offending chemicals — hydrochloric acid, sulfur dioxide, nitrogen oxides, dioxins, furans and heavy metals — as well as small particulates. Timarpur Okhla Municipal Solid Waste (MSW) Management project in Delhi is the first commercial waste-to-energy facility in North India. This will convert one-third of the Delhi garbage into electricity, enough to serve 6 lakh homes. The project is registered with United Nations Framework Convention on Climate Change (UNFCCC) for earning carbon credits. This is the first and largest integrated waste management project set up in the country, aiming for Zero Waste Concept. This works on an environmentally friendly process to generate clean and renewable energy. The plant is aimed at generating 16MW of power from waste. The power plant will use about a third of the daily MSW of Delhi, which stands between 6000 and 8000 tons. NDMC and MCD will be providing the waste free of cost. Similar initiatives elsewhere target to bring electricity to more than 600,000 homes with each plant.

Waste to energy plant diagram...

  California produces more than 60 million bone dry tons of biomass each year. Of this, five million bone dry tons is burned to make electricity. Full 60 million tons of biomass in California could make about 2,000 MW for growing population – enough energy to make electricity for about two million homes. The potential for renewable energy generation from sludge on a national level is enormous. The researchers estimate that California alone generates approximately 700,000 metric tons of dried sludge every year, enough to yield 10 million kilowatt hours daily. Netherlands hosts the world's largest biomass power plant running solely on chicken waste. It converts roughly 440,000 tons of chicken manure into renewable electricity to power 90,000 homes annually. The plant has a capacity to generate more than 270 million kWh of electricity per year. The power plant also takes care of another massive problem – managing the excess of chicken waste, which if left untreated, releases methane – a very potent greenhouse gas.

  Planned, designed and executed on the patented technology developed by an Indian engineer, K.S. Sivaprasad from Tamil Nadu, a waste-to-energy plant of Malaysia won an international award given for top renewable energy plants in the world. The construction of power plant was taken up in Malaysia to handle 700 tons of municipal waste a day and generate 8 MW power. After meeting its consumption of 3 MW, the balance 5 MW was being supplied to the national grid. Malaysian Government then awarded him the next project to handle 1000 tons of waste per day.

Human waste to generate renewable electricity

  Thames Water, U.K. has announced plans to use human waste to generate electricity. Britain’s biggest water company will save £300,000 a year using a new type of fuel – dried human waste. It burns like wood-chip, looks just like instant coffee granules and is a highly combustible new renewable form of fuel, around 16% of electricity needs will be met by so-called poop power – enough to run around 40,000 average family homes. The facility produces approximately five tons of sewage sludge for conversion to fuel chips or flakes, produced after the sludge is heated to 180°C. The resulting flakes are burned to produce electricity.

Thiruneeramalai biogas lights up town at night...

  In Thiruneeramalai in Tamil Nadu, biogas from human waste produces 3,000 watts of electricity daily, enough to keep the town bright at night. The human waste from an area housing complex collects in a sump, where the methane gas produced by the 'sludge' is used to operate a generator. Apart from electricity, the biomass utilisation produces methane for cooking and other applications, and also manure useful for farming. Overall, MSW can be a rich useful material rather than liability. According to MNRE estimates, there exists a potential of about 1460 MW from MSW and 226 MW from MSW and sewage.

Conclusion

  Waste-to-energy (WTE) plants are among the most efficient ways to convert garbage to electricity. WTE plants reduce the waste volume drastically in most eco-friendly manner, at the same time reducing the necessity of landfills. Garbage is very efficiently utilised, and much needed electricity is generated, bridging the gap for electricity requirement. It is time all cities pay attention to this source for power as an economical way to tackle the city waste.


R P Deshpande is most experienced and respected specialists in Indian capacitor sector...

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