Interrelationship of population, environment and development:

Interrelationship of population, environment and development:

Population and Environment: Rapid increase in population disturbs the biotic environment. The rate, at which world population is increasing, is alarming. Human beings are forced to encroach upon forests, mountains, sea and rivers, for space and food. More habitable and cultivable land is required, as also more space is needed for grazing the cattle. Wild animals are being killed indiscriminately for food and money. Trees are being cut to satisfy the needs of fuel and timber. This has caused an ecological crisis. If it is not checked, it is bound to bring disaster. Explosion of population has also caused overcrowding. It has caused physical discomfort, which creates mental tension. Living with mental tension is bound to cause social and health disorders.

Environment and Sustainable Development: In earlier days, human beings were leading a harmonious life with nature. In the age of science and technology, they are capable of using more natural resources to create an environment of their own. As such, the natural environment is shaped, guided and directed by socio-economic considerations. This practice has led to degradation of natural environment. Old villages, hills, beaches, etc., have been converted into cities and big towns. In order to increase communication for trade purposes, a network of roads and transport has been established. Tourism has been given importance and big hotels have been constructed. Agricultural lands have been used in constructing big hotels, industries, etc. Big dams have been constructed in order to generate more electricity for the industries. Water bodies have shrunken.

To maintain a balance between environment and development, it is necessary to strive for sustainable development to meet the needs of present generation without foreclosing the options for future generation. To achieve this, one has to consider different aspects of development. Conservation, sustainability and biological diversity are interrelated. If human beings have to survive, they have to live in harmony with nature. More plants have to be planted. Green grassy patches have to be interspersed between concrete buildings. We will have to adopt such technologies which are environment friendly, sound, and based on maximizing recycling and efficient use of resources.

“Coal Dust Explosion” in Coal fired Cement plant – Its prevention

“Coal Dust Explosion” in Coal fired Cement plant – Its prevention is necessary for safety and enhancement of environment standards.

The numbers of coal fired industrial systems, particularly cement plants, is rapidly increasing, because of high cost and uncertainty in availability of fuel oil and natural gas. Many of the countries do not have access to sufficient quantity of petroleum products; there by, worldwide growth in coal-fired cement plant is tremendous. There is inherent risk associated with coal pulverizing, drying, blending, transportation and storing.

To understand fully the hazard potential of using pulverized coal as a fuel in a cement plant, one should be familiar with the factors responsible for development of coal dust explosion. A typical pulverized coal fuel system process bulk coal into a form that can be efficiently utilized as a fuel to heat the kiln for calcining the raw material of cement, i.e., clay, limestone, etc., into clinker. This is usually accomplished by grinding and drying the bulk feed in a pulverizer so that coal emerging from pulverizer consist 70 to 80% particulate that passes through 200 mesh screen. High temperature air from clinker cooler is often used to dry the coal and convey it from pulverizer to the burning pipe of the kiln. Coal pulverizing is one of the most hazardous jobs from fire and explosion point of view, as both fuel and oxygen are present at the pulverizer. A coal dust explosion is described as rapid burning of combustible particulate within a confined area; which generates a considerable heat and corresponding pressure rise. The factors responsible for coal dust getting exploded:

• presence of dust in suspension at a concentration above flammability limit,
  
• presence of sufficient oxygen to enable the combustion,
  
• source of ignition of the coal dust air mixture,
  
• a certain degree of confinement to the mixture.

Most coal used in firing system have tendency for spontaneous ignition (Spontaneous heating is an inherent property of coal to get heated on oxidation, when it is kept for prolonged time with air or oxygen. Oxidation of coal is an exothermic process, hence the self-ignition) in the pile. Therefore, care should be taken in storage, handling within firing system and prevention of accumulation of coal dust during system operation.

Special precautions are necessary to ensure safe operation:

• use oxygen-deficient air in the pulverizers under normal operating condition,
  
• use of rock dust, carbon dioxide, water systems in the pulverizers and dust collectors when shutdown occurs,
  

• inerting with water sprays or steam when over-temperature conditions are observed,

• care must be taken to prevent development of coal dust cloud,
  
• use of magnet or metal detection to remove foreign iron substance in the system to prevent occurrences of sparks,
  
• cutting & welding operation should be carried out as per the safety norms,
  
• electric components used in the system should be of non-inflammable type,
• hot coal, if any, should be avoided to charge into pulverizers,
  
• proper control measures should be adopted to prevent spontaneous ignition of coal,
  
• prevention of static electricity discharge into the system should be adopted by grounding dust collector bags,
  
• by properly designing of several coal handling equipments in order to prevent accumulation coal dust at various idle spots of locations.

As coal dust explosion in coal-fired industrial systems (whether in a cement plant or in a thermal power plant) is very much serious in nature and may cause damage to the property and personnel, utmost care should be taken to prevent such occurrences. Last but not least, proper training the personnel is most important to handle such situation most effectively.

Environment-friendly Blended cement – Eases pressure on Industrial waste disposal

Environment-friendly Blended cement – Eases pressure on Industrial waste disposal and reducing emissions per unit weight of cement manufactured

Portland Cement, an essential component of concrete, hardens and become strongly adhesive after application; used for various engineering and building construction activities. It is a mixture of Calcium silicate (CaO, SiO2), Calcium aluminate (CaO, Al2O3) in varying proportion, with small amount of magnesium, iron compounds etc. To slowdown the hardening process of cement, sometime Gypsum is also used.

Production of Portland cement is highly gas pollutant; emits considerable amount of Carbon dioxide (CO2) in the atmosphere, polluting air. CO2 is well known for its ill-effects towards Global warming as greenhouse gas. In cement manufacturing plant alone, CO2 produces (a) during de-carbonation of limestone, (b) during kiln fuel combustion, (c) during transportation by vehicles in the cement plant & for cement distribution.

Considering CO2 associated with electric energy consumed by a cement plant, we have observed, for production of 1 tonne of Portland cement 1 tonne of CO2 is produced and emitted to the atmosphere. This is a quite large quantity of CO2 which a Portland cement unit pollutes. To mitigate this extent of pollution menace, many of the steps have been taken by cement industries - production and use of environment-friendly blended cement, i.e., use of alternate or supplementary cementitious materials such as fly ash and slag, is among such steps taken to bring down emission per unit weight of cement manufactured. In addition to reduction of emission per unit weight of cement manufactured, it eases problem of Industrial waste disposal; as both fly-ash and slag are the waste from thermal power and steel making industry respectively, available abundantly almost at free of cost.

Fly-ash blended cement: Fly ash is the waste generated by thermal power units, resulting from combustion of powdered coal. Fly ash consists of mostly Silicon dioxide (SiO2), Aluminum oxide (Al2O3) and Iron compounds. It is pozzolanic, i.e., it reacts with calcium hydroxide and alkali to form cementitious materials.

Activated Fly ash can replace up to 50% by mass in blended cement. It is less expensive and it is advantageous in a host of applications. Fly ash can be used to improve workability and pumpability of concrete. Due to its generally slower rate of hydration, fly ash also lowers the heat of hydration and is important in mass concrete structures, such as large foundations, bridges, and piers. High fly ash concrete shows less bleeding and shrinkage than straight cement mixes. Fly ash is also used as a component in the production of flowable fill, which is used as self-leveling, self-compacting backfill material in lieu of compacted earth or granular fill.

Due above advantages of fly ash blended cement, more and more fly ash is being used beneficially as a recycled material.

Slag blended cement: Slag is the waste product of iron making industry. These are the impurities present in iron ore and obtained from blast furnace while processing for pig iron. It was found that ground granulated slag reacts with water to produce cementitious properties. Therefore it is used in concrete in combination with Portland cement as part of blended cement. Concrete containing ground granulated slag develops strength over a longer period, leading to reduced permeability and better durability properties. Slag cement concrete is less vulnerable to alkali-silica and sulfate attack.

As with fly ash, processing blast furnace slag into slag cement or slag aggregate eases the burden on environment. Apart from reducing the burden of waste disposal, it reduces the air emissions at the cement kiln as well as the material in landfills. Most significantly, slag decreases Portland cement usage by as much as 50 percent, thereby diminishing CO2 emissions, the amount of energy required to produce concrete, and the quantity of virgin land extraction through mining raw materials for Portland cement.

Concrete made with blended cement has generally higher density than concrete made with Ordinary Portland Cement. Hence it improves the impermeability and durability. All these make for better long-term strength, dense and impermeable concrete and improved corrosion resistance and longer service life with reduced cost for repairs and maintenance.

Thus, the Blending cement is not only environment-friendly, but also make improved concrete performance.

Cleaner Coal-fired ‘Supercritical Power plants’

High performance Coal-fired ‘Supercritical Power plants’ – Promotes cleaner environment

As name suggests, Coal-fired Supercritical power plants operate at very high temperature and pressure (580 degree centigrade temp. and at a pressure of 23 MPa) resulting much higher heat efficiencies (46%), as compare to sub-critical coal-fired plants which operates at 455 degree centigrade temp., and efficiency of within 40%. Some of the benefits of advanced supercritical power plants include:

• Reduced fuel costs due to improved plant efficiency;

• Significant improvement of environment by reduction in CO2 emissions;

• Plant costs comparable with sub-critical technology and less than other clean coal technologies;

• Much reduced NOx, SOx and particulate emissions;

• Can be fully integrated with appropriate CO2 capture technology.

In other words, supercritical power plants are highly efficient plants with best available pollution control technology, reduces existing pollution levels by burning less coal per megawatt-hour produced, capturing the vast majority of the pollutants. This increases the kWh produced per kg of coal burned, with fewer emissions.

Because of the above techno-economic benefits along with its environment-friendly cleaner technology; more and new power plants are coming-up with this state-of-the-art technology. As environment legislations are becoming more stringent, adopting this cleaner technology have benefited immensely in all respect. As LHV (lower heating value) is improved (from 40% to more than 45%); a one percent increase in efficiency reduces by two percent, specific emissions such as CO2, NOx, SOx and particulate matters.

"Supercritical" is a thermodynamic expression describing the state of a substance where there is no clear distinction between the liquid and the gaseous phase (i.e. they are a homogenous fluid). Water reaches this state at a pressure above 22.1 MPa. The efficiency of the thermodynamic process of a coal-fired power describes how much of the energy that is fed into the cycle is converted into electrical energy. The greater the output of electrical energy for a given amount of energy input, the higher the efficiency. If the energy input to the cycle is kept constant, the output can be increased by selecting elevated pressures and temperatures for the water-steam cycle.

There are various operational advantages in case of supercritical power plant:

• There are several turbine designs available for use in supercritical power plants. These designs need not fundamentally differ from designs used in sub-critical power plants. However, due to the fact that the steam pressure and temperature are more elevated in supercritical plants, the wall-thickness and the materials selected for the high-pressure turbine section need reconsideration. The supercritical plant needs once-through boiler, where as drum type boiler is required by sub-critical power plant. In fact, once-through boilers are better suited to frequent load variations than drum type boilers, since the drum is a component with a high wall thickness, requiring controlled heating.

• The performance of supercritical plant depends on steam condition. Steam conditions up to 30 MPa/600°C/620°C are achieved using steels with 12 % chromium content. Up to 31.5 MPa/620°C/620°C is achieved using Austenite, which is a proven, but expensive, material. Nickel-based alloys, would permit 35 MPa/700°C/720°C, yielding efficiencies up to 48%. Lot R&D inputs and allying with suppliers are required to achieve higher performance.

• Moreover, fuel Flexibility is not compromised in Once-Through Boilers. A wide variety of fuels have already been implemented for once-through boilers. All types of coal as well as oil and gas have been used.

• Current designs of supercritical plants have installation costs that are only 2% higher than those of sub-critical plants. Fuel costs are considerably lower due to the increased efficiency and operating costs are at the same level as sub-critical plants. Specific installation cost i.e. the cost per megawatt (MW) decreases with increased plant size.

Because of the high performance, efficiency and preservation of much cleaner environments than sub-critical coal-fired power plants, more than 400 supercritical coal-fired power plants are operating in the developed countries like US, Europe, Russia and in Japan. Most of the new power plants coming up now-a-days are of supercritical coal-fired technology.

Guidelines for making City Green

As cities are keep on growing because of urbanization, more and more cities are becoming congested. To make cities livable for the citizen and to make their life beautiful, it has been the constant endevour of the Government to encourage for green building, keep city pollution within the limit and to create sufficient green belt.

A. Green Building is a philosophy of design and construction that integrates natural resources more effectively, preserves and restores the natural and human resource base while creating healthier, more efficient “high-performance” structures, homes and communities. This philosophy incorporates the following guiding principles:

• Using natural and manmade resources efficiently;

• Considering the impact of buildings and development projects on the local, regional and global environment;

• Reducing building footprint and development size;
  

• Allowing ecosystems to function naturally;

• Conserving and reusing water; treating storm water on-site;

• Maximizing the use of local materials;

• Optimizing energy performance by installing energy efficient equipment and systems;
  

• Optimizing climatic conditions through site orientation and design;
  

• Integrating natural day-lighting and ventilation;

• Minimizing the use of mined rare metals and persistent synthetic compounds and volatile organic compounds;
  

• Minimizing construction waste by reducing, reusing and recycling materials during all phases of construction and deconstruction.

Sustainability is the practice of using resources to provide for the needs of today’s citizens while preserving the use of those same resources for the needs of future generations. Generally, objectives of green buildings are: (a) Improve work and learning environments, thus increasing worker productivity and student performance; (b) Mitigate health risks such as asthma and childhood lead poisoning; (c) Create local green building jobs within every existing industrial sector; (d) Reduce energy consumption and costs; (e) Affirm the City’s commitment to environmental conservation.

B. The creation of green-space in cities is often spoken of as if it were the result of orderly planning or regulation. Most of the cities have a plan to conserve green-space on the urban fringe. Generally, planning for creation of city green zones includes:

• Greening Commercial Corridors – This focus on landscape enhancements along strategic streets that can serve as a neighborhood's economic lifeline.

• City Parks Revitalization – This focus on maintaining and beautification of existing parks in a city.

• Setting-up of New Community Gardens;
  

• Street Beautification Projects- creation of "Garden Blocks".

· Education and Training Opportunities - Courses and workshops help city dwellers beautify their communities through horticulture.

C. Apart from setting up green buildings, green covers, strategy for implementing proper solid waste management, restricting generation of air / water pollutants and strict implementation of local emission control codes. Thus, guidelines should include:

• Utilize sites to capture environmental benefits and preserve or create new open space;
  

• Develop programs and policy to conserve potable water use, improve stormwater management and “green” the city sewage waste water system;
  

• Address city and regional transportation issues by encouraging transit-oriented development, improve public transit services and reduce dependency on individual automobile use;

• Implement citywide energy conservation programs and incentives, encourage use of renewable, non-fossil fuel energy sources and improve city performance on meeting regional clean air standards;
  

• Promote the development of local, green manufacturing industries and the use of recycled content materials or renewable materials for building, operations, and supplies for city work. Also establish more extensive recycling program to include construction and demolition waste recycling;
  

• Maintain city’s sustainable development by integrating programs, such as in workforce development, economic redevelopment, and the public school system.

D. Citywide ban on smoking in all enclosed public spaces and public vehicles, also to be imposed for long term benefit of its citizen.

Planned city development emphasizes value of environment and heritage:

Transformation of rapid urbanization in developing world due to industrialization has necessitated to the planned city development. In general, the planned city development include environmental sustainability, heritage conservation, appropriate technology, infrastructure efficiency, place making, "social access," transit oriented development, regional integration, human scale, and institutional integrity. Some of these points are discussed below:

Balance with nature: Balance with nature emphasizes the distinction between utilizing resources and exploiting them. It focuses on the thresholds beyond which deforestation, soil erosion, aquifer depletion, siltation and flooding. The principle promotes environmental assessments to identify fragile zones, threatened eco-systems and habitats that can be enhanced through conservation, density control, land use planning and open space design. Balance with nature do not support any act against nature, which include cutting of hillside trees, quarrying on slopes, dumping sewage and industrial waste into the natural drainage system, paving and plinthing excessively, and construction on steep slopes.

Balance with tradition: Balance with tradition integrate plan interventions with existing cultural assets, respecting traditional practices and precedents of style. It calls for respect for the cultural heritage of a place. It also promotes architectural styles and motifs designed to communicate cultural values. Aesthetic sense of the area should be maintained.

Appropriate Technology: Appropriate technology emphasizes the employment of building materials, construction techniques, infrastructural systems and project management which are consistent with local contexts.

Cordiality: It is well known that, vibrant societies are interactive, socially engaging and offer their members numerous opportunities for gathering and meeting one another. Therefore modern society calls for cordiality among everybody. Design should follow promotion of interactive behaviour of society. It leads to creation of places of solitude for individual; spaces for “beautiful, intimate friendship” where unfettered dialogue can happen; place where the individual socializes into a personality; creation of city level domains like plazas, parks, stadium, transport hubs, gallerias etc.

Efficiency: The principle of efficiency promotes a balance between the consumption of resources such as energy, time and fiscal resources, with planned achievements in comfort, safety, security, access, tenure, and hygiene. It encourages optimum sharing of public land, roads, facilities, services and infrastructural networks reducing per household costs, while increasing affordability, access and civic viability.

Planned urban developments – way to improve environment in cities

Rapid urbanization is transforming life throughout the developing world. Urbanization as a process is in itself is the biggest challenge for cities. It is also irreversible process. Urban planners claim that, urbanization is similar to an inevitable evil. The hub of civilization has been cities since the advent of industrial age. The economic process surrounding it is built on exploitation of nature and resources, killing rural outpost, creating inequalities and driving people to high density spaces – leaving rural spaces more exposed to un-controlled exploitation. Cities continue to grow in a haphazard manner. The city crises are many facets but it is only the clogged roads that are seen to be for what they are: impossible to live with. Issues like having enough water and power and getting rid of waste are considered serious.

The biggest challenges for these cities are increase in human density, which leads to problem of food, clothing & sheltering, sanitation, increasing number of slums and so the environmental degradation. Shortage of proper education, better health facilities, and most importantly a gap in demand and supply chain which contribute towards illegal operations getting started in those areas. In addition, low infrastructural and transport facilities in relation to the population growth make living condition problematic. Urban development is the key indicator for information of development indices. Some of the factors and problems to addressed are summerised as: (a) stable political situation, (b) economic strength, (c) corruption issue and public awareness, (d) skilled urban planners, (e) international relations for cultural sharing, (e) most important of all is willingness in the people and government to support for development.

Planned urban development is the key to overcome such problem of urbanization. Good land planning and infrastructure building in developing countries would help to create a perfect base which can be further nurtured with pollution free environment with sufficient greenery, better delivery of basic services like water and sanitation and finally a society with decent living. Research and demonstration are urgently needed if we are to realize our common dream of dynamic, environmentally and use-friendly cities. It is possible to revitalise depressed areas in ways that satisfy the wishes of residents and businesses. Resources such as land and materials can be reused and recycled. The scope for improving the way that buildings are designed, constructed and disposed of is tremendous. In managing the built environment, sustainability must be incorporated at various levels, from regional planning to individual construction sites. Planners, city councils, designers and urban residents all help to determine how cities develop and what construction methods are used.

Environmental issues play a central role in urban planning. However, in emerging megacities, infrastructure growth often takes precedence over the environment. Solving transportation issues has the highest priority in the cities surveyed, and air pollution is seen as the main environmental issue. The environment also plays a major role in the area of energy issues. Thus, alternative sources of energy will have a bright future in megacities. To meet growing demand for mobility, power, energy and water in the long term, megacities must not only build out their infrastructures and use them more efficiently; they must also proactively manage demand. However, city government experts are aware of the fact that efficiency must be improved significantly.

Control of Air pollution by controlling Particulate Matters

Airborne Particulate Matters (PM) - Pollution Prevention and Control:

Airborne particulate matters (PM) emissions can be minimized by pollution prevention and emission control measures. Prevention, which is frequently more cost-effective than control, should be emphasized. Special attention should be given to mitigate the effects, where toxics associated with particulate emissions may pose a significant environmental risk.

Measures such as improved process design, operation, maintenance, housekeeping, and other management practices can reduce emissions. By improving combustion efficiency in Diesel engines, generation of particulate matters can be significantly reduced. Proper fuel-firing practices and
combustion zone configuration, along with an adequate amount of excess air, can achieve lower PICs (products of incomplete combustion). Few following steps should be adhered to control PM:

1. Choosing cleaner fuels - Natural gas used as fuel emits negligible amounts of particulate matter.

2. Low-ash fossil fuels contain less noncombustible, ash-forming mineral matter and thus generate lower levels of particulate emissions.

3. Reduction of ash by coal cleaning reduces the generation of Particulate Matter (PM) emissions.

4. The use of more efficient technologies or process changes can reduce PIC emissions.

5. Advanced coal combustion technologies such as coal gasification and fluidized-bed combustion are examples of cleaner processes that may lower PICs by approximately 10%.

6. A variety of particulate removal technologies, are available – these are (a) Inertial or impingement separators, (b) Electrostatic precipitators (ESPs) , (c) Filters and dust collectors (baghouses), (d) Wet scrubbers that rely on a liquid spray to remove dust particles from a gas stream.

The principal methods for controlling the release of particulate matter are summarized here.

• Identify measures for improving operating and management practices.

• Consider alternative fuels such as gas instead of coal.

• Consider fuel-cleaning options such as coal washing, which can reduce ash content by up to 40%.

• Consider alternative production processes and technologies, such as fluidized bed combustion, that result in reduced PM emissions.

• Select optimal particulate removal devices such as ESPs and Baghouses.

Air pollution by Particulate matters (Fine and Coarse Dust particles):

Air pollution by Particulate matters (Fine and Coarse Dust particles):

‘Fine particles’ are less than 2.5 micron in size and require electron microscope for detection, however, they are much larger than the molecules of Ozone etc., and other gaseous pollutants, which are thousands times smaller and cannot be seen through even electron microscope.

Fine particles are formed by the condensation of molecules into solid or liquid droplets, whereas larger particles are mostly formed by mechanical breakdown of material or crushing of minerals. ‘Coarse particles’ are between 2.5 to 10 micron size, and cannot penetrate as readily as of Fine particle; however, it has been seen these are responsible for serious health hazards. The severity of the health hazards vary with the chemical nature of the particles.

The inhalation of particles has been linked with illness and deaths from heart and lung disease as a result of both short- and long-term exposures. People with heart and lung disease may experience chest pain, shortness of breath, fatigue etc., when exposed to particulate-matter pollutants. Inhalation of particulate matter can increase susceptibility to respiratory infections such as Asthma, Chronic Bronchitis. The general medical term given for such lung diseases is ‘Pneumoconiosis’.

Emissions from diesel-fuel combustion in vehicles / engines / equipments; Dusts from cement plants, power plants, chemical plants, mines are a special problem, specially for those individuals breathing in close proximity to such atmosphere. Cars, trucks and off-road engines emit more than half a million tones of diesel particulate matter per year.

WE SEEK YOUR HELP TO SAVE ENVIRONMENT

Your few following small steps and effective decisions in everyday life would be a big leap in helping us to improve global environment.

1. Make energy efficient and conservation wise decisions in every sphere of life.
2. While driving motor vehicle, turn off the engine if waiting is longer. More fuel is wasted when idling than restarting. Be alert in traffic. Try to take alternate routes which have few signals to eliminate idling.
3. Warm-up the motor vehicle for one minute before moving. Accelerate gently and evenly and use your cruise control to maintain a steady speed.
4. Use motor vehicle's flow through vents instead of air conditioning (which decreases fuel efficiency by 21%) or by opening window.
5. Keep car engine tuned. A poorly tuned car wastes 15% more fuel. More fuel, means more pollution and travel fewer miles.
6. Properly inflate & align tires to save fuel & to reduce wear on tires over time.
7. Reduce the amount of miles you drive. Fewer distance driven, fewer polluting emissions created. Walk or ride a bike!
8. Use fuel efficient automobiles. Follow state guidelines on emissions testing & maintain any pollution-control devices.
9. Use public transportation when available.
10. Conserve electricity, including turning off lights when not in use.
11. Participate in recycling programs. Recycling conserves energy and also conserves natural resources.