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Waste is a resource. Generating energy from waste instead of sending it to landfill avoids methane gas which equals 25 times CO₂ in mass. In combination with the energy efficiency thresholds set in Waste Framework Directive, this could prevent up to a further 45 million tons of CO₂ eq. per year. The purpose of this paper is to present the waste-to-energy (WTE) plants installed in ten European cities which have been selected among the most sustainable cities or among the best cities to live in.

The work is based on literature review and a combination of several statistical data and reports that include the required data.

The European Directives, along with the general thinking that wastes are resources and the effort to reduce the environmental impact in urban environment from waste management, were the driving forces. The most sustainable cities in EU considered that their sustainability is based also in energy recovery from wastes. All of them are using WTE facilities to treat a significant part of their waste in order to produce energy in the form of heat and electricity. And they do it in a very successful and environmental friendly way, as they mainly utilize the waste fractions that cannot be recycled or reused, and they do not landfill these resources. This approach is proving that the sustainable waste management cannot be achieved without WTE facilities, since a fraction of wastes consists of non-recyclable and non-reusable materials, which present significant heating value that cannot be neglected as an energy source.

This paper presents the WTE plants installed in ten European cities which have been selected among the most sustainable cities or among the best cities to live in. This work aims to present the strong and successful relation between WTE and sustainability in the modern complex urban environment.

Cement production has advanced greatly in the last few decades. The traditional fuels used in traditional kilns include coal, oil, petroleum coke, and natural gas. Energy costs and environmental concerns have encouraged cement companies worldwide to evaluate to what extent conventional fuels can be replaced by waste materials, such as waste oils, mixtures of non-recycled plastics and paper, used tires, biomass wastes, and even wastewater sludge. The paper aims to discuss these issues.

The work is based on literature review.

The clinker firing process is well suited for various alternative fuels (AF); the goal is to optimize process control and alternative fuel consumption while maintaining clinker product quality. The potential is enormous since the global cement industry produces about 3.5 billion tons that consume nearly 350 million tons of coal-equivalent fossil and AF. This study has shown that several cement plants have replaced part of the fossil fuel used by AF, such waste recovered fuels. Many years of industrial experience have shown that the use of wastes as AF by cement plants is both ecologically and economically justified.

The substitution of fossil fuels by AF in the production of cement clinker is of great importance both for cement producers and for society because it conserves fossil fuel reserves and, in the case of biogenic wastes, reduces greenhouse gas emissions. In addition, the use of AF can help to reduce the costs of cement production.

The purpose of this paper is to evaluate the green energy generation potential of the organic fraction of municipal solid waste (OFMSW) through anaerobic digestion (AD) route in India and its benefits.

In this study, performances of some AD plants presently operating successfully in India have been studied in the field (Section 3.1). Primary data collected from this study has been used to evaluate the biogas generation potential of OFMSW in Indian condition (Section 4). To ensure the validity, this gas generation potential has been compared with the gas yield data observed by the other researchers and with the gas yields of AD plants of some technology providers at some parts of the world (Section 4.1). From the future population projection (year 2030) and the future per capita waste generation rate obtained from the literature survey, estimation has been made for future quantity of municipal solid waste (MSW) (year 2030) (Section 2.3). Based on these data, the green energy generation potential from the bio-degradable portion of MSW through AD route, in India, has been evaluated (Section 4.2), and its economic and environmental benefits have been analyzed (Section 5) .

This secondary research work reveals that from the bio-degradable portion of MSW, India can generate about 583 MW of green energy daily and produce about 5.1 mil MT of bio fertilizer per annum presently, and these may go up to 2,273 MW and 19.5 mil MT, respectively, in the year 2030. Generation of green energy from OFMSW, in India, may save coal consumption of about 3.04 mil MT and reduce 35.42 mil MT of CO₂ emissions per annum presently. Moreover, utilization of the bio-degradable portion of the MSW stream may save about 550 acres (2.23 sq. km) of landfill area per year presently and in total may save about 8,182 hectare (82.5 sq. km) of landfill area during the period of 15 years time.

The population growth and future per capita waste generation rate are based on census report of Govt of India and survey report of World Bank, respectively. Separate collection of bio-degradable portion of MSW has not yet been developed properly in India.

This study reveals that in India, the high-moisture-content, low-calorific-value bio-degradable waste in India can be used for the generation of substantial amount of green energy in India, which in addition to financial gains would reduce the waste quantity at landfill site, conserve natural resources, save land, reduce green house gas emission, generate employment and help to protect environment. Considering these benefits and advantages, evaluated in this study, policy makers and city managers may review their approaches toward solid waste management system of their cities to meet the challenges of huge increase of MSW in the years to come in India. More research works may be initiated to improve the AD system of organic waste, and more capital may be employed in waste management business in India.

Numbers of research works have been carried out by other researchers for estimation of energy generation potential through AD of OFMSW for different countries; but no such work could be found to identify such potential and its benefits in India. This research work demonstrates how MSW can be used as a wealth for green energy production in India. The originality of this paper is the analysis of green energy generation potential from the low calorific value MSW in India.