ENVIRONMENTAL IMPACT OF ELECTRICITY GENERATION

ENVIRONMENTAL IMPACT OF ELECTRICITY GENERATION

All energy conversion methods used to produce electricity have some environmental impact. The impact may have an active effect like the emission of airborne pollutants, or may have a passive effect like aesthetics or habitat modification. Even methods considered environmentally friendly, like wind, solar, and hydro, have some impact on the environment. Not only does the final production of electricity have an environmental impact but the transmission of electricity with concerns over electromagnetic fields, aesthetics, and land use, also impacts the environment.

The whole cycle of electricity generation must be considered when looking at the environmental impact. This includes the production and transportation of fuel for the conversion process. This is especially true of fossil fuel and nuclear power plants, which use large quantities of fuel taken from the earth. Energy system environmental impact consists of fuel recovery and production, fuel transportation, electricity transmission, and spent fuel emissions.

Fossil fuel power plants generally have the most widespread effect on the environment, as the combustion process produces airborne pollutants that spread over a wide area. Nuclear power plants have the most potentially dangerous effect. An operating accident at a nuclear station could allow a large release of radioactive particles to occur. Solar, hydro, and wind power plants generally have smaller effects on the environment.

Nonetheless, these renewable sources of energy provide substantial benefits for our climate, our health and our economy. Each source of renewable energy has unique benefits and costs like little to no global warming emissions, improved public health and environmental quality and a vast and inexhaustible energy supply etc.

ENVIRONMENTAL IMPACTS OF HYDROELECTRIC POWER

Hydroelectric power includes both massive hydroelectric dams and small run-of-the-river plants. Large-scale hydroelectric dams continue to be built in many parts of the world leaving a lasting impact on the world. The amount of water usage is often of great concern for electricity generating systems as populations increase and droughts become a concern.

Still, hydroelectric power is the most energy efficient power generator. Currently, hydropower is capable of converting 90% of the available energy into electricity. This can be compared to the most efficient fossil fuel plants, which are only 60% efficient.

LAND USE

The size of the reservoir created by a hydroelectric project can vary widely, depending largely on the size of the hydroelectric generators and the topography of the land. Hydroelectric plants in flat areas tend to require much more land than those in hilly areas or canyons where deeper reservoirs can hold more volume of water in a smaller space. Flooding land for a hydroelectric reservoir has an extreme environmental impact: it destroys forest, wildlife habitat, agricultural land, and scenic lands. In many instances, such as the Three Gorges Dam in China, entire communities have also had to be relocated to make way for reservoirs.
Dammed reservoirs are used for multiple purposes, such as agricultural irrigation, flood control, and recreation, however  hydroelectric facilities can still have a major impact on aquatic ecosystems. For example, though there are a variety of methods to minimize the impact (including fish ladders and in-take screens), fish and other organisms can be injured and killed by turbine blades.

WILDLIFE IMPACTS

Yet, before a project can be developed, it must go through a rigorous process of screening that examines the impact the project would have on the environment and the local communities. Water flow, water quality, water shed management, fish passage, habitat protection as well as the welfare and lifestyle of the local communities are taken into consideration.

Although hydroelectric power can prove to be a challenge to the environment, it yet has a distinct advantage over fossil fueled generator plants: it is clean, green and renewable and has very low operating costs. It is renewable because it draws its essential energy from the sun that drives the hydrological cycle, which in turn provides a continuous renewable supply of water. Hydropower does not contribute to local air pollution.

DAYLIGHT SAVING TIME

Daylight saving time —also summer time in British English— is the practice of advancing clocks during the lighter months so that evenings have more daylight and mornings have less. Typically clocks are adjusted forward one hour near the start of spring and are adjusted backward in autumn.

The modern idea of daylight saving was first proposed in 1895 by George Vernon Hudson and it was first implemented by Germany and Austria-Hungary starting on 30 April 1916. Many countries have used it at various times since then. Much of the United States used DST in the 1950s and 1960s, and DST use expanded following the 1970s energy crisis. It has been widely used in North America and Europe since then.

The rationale behind the 1975 study of DST-related energy savings was that energy use and the demand for electricity for lighting homes is directly related to the times when people go to bed at night and rise in the morning. In the average home, 25 percent of electricity was used for lighting and small appliances, such as TVs and stereos. A good percentage of energy consumed by lighting and appliances occurred in the evening when families were home. By moving the clock ahead one hour, the amount of electricity consumed each day decreased.

In the summer, people who rose before the sun rises used more energy in the morning than if DST were not in effect. In the winter, the afternoon Daylight Saving Time advantage is offset for many people and businesses by the morning's need for more lighting. In spring and fall, the advantage is generally less than one hour. So, the rationale was that Daylight Saving Time saves energy for lighting in all seasons of the year, but it saves least during the four darkest months of winter (November, December, January, and February), when the afternoon advantage is offset by the need for lighting because of late sunrise.

In addition, less electricity was thought to be used because people are home fewer hours during the "longer" days of spring and summer. Most people plan outdoor activities in the extra daylight hours. When people are not at home, they don't turn on the appliances and lights. 

Inception and Evolution of Electricity in India.

HISTORY AND EVOLUTION OF ELECTRICITY

Electricity, as we know it, is largely a product of eighteenth and nineteenth century scientific and engineering developments. At the very inception in our country the consumption of electricity was started for lightening the palaces of the King of Coochbehar in West Bengal and the King of Bikaner in Rajasthan

In December, 1896 Indian Electric Company, which was registered in London in 1895, was favored with the license to distribute and sell electricity in 5.6 Square Mile area in the city of Calcutta, the then capital of India, under Calcutta Electricity Lighting Act for 21 years. Kilbern & Co. was engaged as agent of the said Indian Electricity Company with effect from the 7th January, 1897. The private entrepreneurships solely were engaged in generation, distribution, and sale and in development of electricity in our country up to the year 1948 prior to enactment of the Indian Electricity Act 1948. The number of electrified villages and pumps engaged in agriculture were 1500 and 6500 respectively. Per capita consumption of electricity in India was only 16 units at that time. 

CHANGE IN POWER SECTOR POST INDEPENDENCE:

The power sector in India has undergone significant progress after Independence. When India became independent in 1947, the country had a power generating capacity of 1,362 MW.
Hydro power and coal based thermal power have been the main sources of generating electricity. Generation and distribution of electrical power was carried out primarily by private utility companies.

Notable amongst them and still in existence is Calcutta Electric. Power was available only in a few urban centers; rural areas and villages did not have electricity.

After 1947, all new power generation, transmission and distribution in the rural sector and the urban centers (which were not served by private utilities) came under the purview of State and Central government agencies. State Electricity Boards (SEBs) were formed in all the states. Nuclear power development was introduced, in late sixties. The concept of operating power systems on a regional basis crossing the political boundaries of states was introduced in the early sixties. 

GENERATORS- AN OVERVIEW

The generator evolved from the work done by Michael Faraday along with Law Joseph Henry, who in the 1820s discovered the operating principal of electromagnetic generators. This principle is now called Faraday's. Once these two inventors discovered and documented the phenomena of electromagnetic induction, it lead to experimentation by others in both Europe and North America.

Diesel powered generators, or electrical generator sets, are used in countless industrial and commercial establishments. These generators can be used for small loads, such as in homes, as well as for larger loads like industrial plants, hospitals, and commercial buildings. They can either be prime power sources or standby/back-up power sources. They are available in various specifications and sizes. Diesel generator sets rating 5-30KW are typically used in simple home and personal applications like recreational vehicles. Industrial applications cover a wider spectrum of power ratings (from 30 kW to 6 Megawatts) and are used in numerous industries throughout the world. For home use, single-phase power generators are sufficient. Three-phase power generators are primarily used for industrial purposes.

There are two types of generators: permanent and standby. The permanent ones run on an existing fuel source – either liquid propane or natural gas and are capable of generating enough wattage. The portable generators are smaller and can be wheeled around. Their primary source of fuel is gasoline. Generators are reasonably safe as long as the safety precautions are met and no misuse takes place. Generators are best used outdoors where it is well ventilated as the carbon monoxide that a generator releases can prove fatal if inhaled over a period of time. Generators have a low voltage system along with economic benefits and low operating costs and maintenance costs. The systems are extremely compact with a simple design. 

Blow-by gases

Is your diesel generator leaking fumes? Not to worry, a small percentage of gas will escape during normal operations?
Learn about ‘Blow- by’ gases...

Blow-by gases are present with all internal combustion engines.

A healthy engine will normally have a Blow-by of 1% of its swept volume (flow in LPM – Litre per minute).

Blow-by is the gas that enters to engine’s crankcase during Power Stroke and  Compression Stroke. This gas is composed of unburnt fuel,  air and combustion by-products.

 

BLOW-BY FLOW PATHS

Blow-by happens because perfect sealing between the Cylinder wall (Cylinder Bore) and Piston is not possible. The tangential load pressing the Piston Rings into the bore wall create a good seal, but still there are gaps, and gases get through them and enters the Crankcase. Refer the figures to see the gaps.

The Blow-by gases enters the crankcase, if they are left unchecked it will eventually build up pressure and can cause the oil to be blown past the crankshaft and camshaft seals !!

Some engine design have a Open Breathing System where the Blow-by gases are breathed out to atmosphere and some design have a Closed Breathing System where the Blow-by gases re-enter into the air intake system.

If engine is put under full load during starting (when the piston temperature is yet to reach its operating temperature) it will cause accelerated wear and tear of the Cylinder Bore. Worn out cylinder leads to increased blow-by and loss of power. It is always advisable to give sufficient time to warm-up before the engine is put under load.