12 May 2011

Explain about various forms of energy sources.

The energy sources available can be divided into three types.
1. Primary Energy Sources
2. Secondary Energy Sources
3. Supplementary Sources

I. Primary Energy Sources:

          It can be defined as sources which provide a net supply of energy. Coal, natural gas, oil and nuclear energy using breeder reactor are examples of this type. The energy required to obtain these fuels is much less than what they can produce by combustion or nuclear reaction. Their energy yield ratio is very high. The yield ratio is defined as the energy fed back by the material to the energy received from the environment. The primary fuels only can accelerate growth but their supply is limited. It becomes very essential to use these fuels sparingly. Primary fuels contributes considerably to the energy supply.

II. Secondary Fuels:

          Secondary fuels produce no net energy. Though it may be necessary for the economy, these may not yield net energy. Intensive agricultural is an example wherein terms of energy the yield is less than the input. Secondary sources are like solar energy, wind energy, water energy etc.

III. Supplementary Sources:

          It is defined as those whose net energy yield is zero and those requiring highest investment in terms of energy insulation (thermal) is an example for this source.

2. Discuss about obstackles to the implementation of renewable energy.

          Experience with renewable energy projects in the developing countries indicates that there are a number of barriers to the effective development and widespread diffusion of these systems. Among these are: 

1. Inadequate documentation and evaluation of past experience, a paucity of validated field performance data and a lack of clear priorities for future work.

2. Weak or non-existent institutions and policies to finance and commercialize renewable energy systems. With regard to energy planning, separate and completely uncoordinated organizations are often responsible for petroleum, electricity, coal, forestry, fuelwood, renewable resources and conservation.

3. Technical and economic uncertainties in many renewable energy systems, high economic and financial costs for some systems in comparison with conventional supply options and energy efficiency measures.

4. Skeptical attitudes towards renewable energy systems on the part of the energy planners and a lack of qualified personnel to design, manufacture, market, operate and maintain such systems.

5. Inadequate donor coordination in renewable energy assistance activities, with little or no information exchange on successful and unsuccessful projects.

3. Write short note on conventional energy systems.

          Non-renewable energy sources are those which are used much faster than they can be produced and which are finite in their extent. For example, coal takes millions of years to form. The examples of non-renewable energy sources include coal, oil and natural gas.

i. Coal:

          Most of the coal in use today was formed about 300 million years ago when fresh water swamps covered substantial portions of the earth. The rapid growth of vegetation and its slow decay under water resulted in the formation of peat. The peat was compressed by the weight of overlying sediments and rock resulting in the formation of increasingly valuable and lower moisture content fuels such as lignite, bituminous (soft) coal, and anthracite (hard coal). Lignite has about 40% water whereas bituminous coal has about 3% water. Anthracite is an even more concentrated energy source, but is a scarce resource.

          Coal is the most abundant fossil fuel and supplies about 27% of world energy. Bituminous coal is the most commonly used coal, supplying about 75% of the total coal used. Coal deposits generally lie underground.

ii. Oil and Natural Gas:

          Oil and natural gas originated from microscopic marine organism (plankton). These organisms accumulated in large deposits which again were buried by sediments. Since they did not have the large quantities of cellulose like the marsh plants, they broke down into a liquid substance known as petroleum. The muddy sediment became shale and in the process the petroleum was extruded into the surrounding area. If that area was made up of porous sandstone and it had an impermeable cap rock over it, then the petroleum is accumulated in the sandstone layer. Some of the petroleum was broken down into methane and accumulated above the oil as natural gas. Thus, rather special conditions were necessary for petroleum formation and these conditions were unevenly distributed throughout the world with a large share occurring in the Middle East. 

India is not particularly rich in petroleum reserves. The potential oil bearing areas are located in Assam, Tripura, Manipur, West Bengal, Ganga valley, Punjab, Hiamachal Pradesh, Kutch, eastern and western coastal area (in Tamil Nadu, Andra Pradesh and Kerala). Andaman and Nicobar Islands, Lakshadweep, and in the continental shelves adjoining these areas.

          Diesel power plants in India are installed in isolated places and the total installed capacity is estimated as 0.35 million kW i.e. less than 2% of the total installed capacity in the country. 

iii. Natural gas:

          Gas is incompletely utilized at present and huge quantities are burnt off in the oil production process because of the non-availability of ready market. The reason may be the high transportation cost of the gas. To transport gas is costlier than transporting oil. 

          Natural gas supplies about 23% of the world’s energy. Transport of natural gas presents a problem in more remote areas. Pipelines are only effective across land areas and less than global distances. Ocean shipping of natural gas is only just beginning as methods are found to concentrate it such as liquefied natural gas or methanol. Natural gas is currently used mostly for heating and cooking, but it is also used in manufacture of petrochemicals and fertilizers. More than 2/3 of natural gas reserves are located in Russia and Middle East. 

Gaseous fuels can be classified as:

1. Gases of fixed composition such as ethylene, methane etc.
2. Composite industrial gases such as producer gas, coke oven gas, water gas, blast furnace gas etc.

4. Discuss about the environmental and health impacts of conventional energy systems.

Environmental and Health Impacts:

Health, Safety and Environmental Concerns of coal

          * Physical damage to the landscape is generally extensive through deforestation

          * loss of biodiversity

          * Burning of coal releases CO2, which causes green house effect and global warning

Health, Safety and Environmental Concerns of oil

          * Physical damage to the landscape is generally not overwhelming for oil extraction

          * The obvious exception is in remote areas where major roads must be constructed across habitat which may be sensitive even road construction may be very destructive

          * Oil transport is a major source of potential contamination.  Catastrophic oil spills have made the headlines over the years, which have been very destructive within a localized area

          * Incomplete burning of oil fuels contributes to smog and other forms of air pollution

          * Combustion of oil is another source of Co2 and consequently global climate change

Health, Safety and Environmental Concerns of Natural Gas

          * The biggest health and safety concern is the explosive nature of natural gas

          * Pipeline explosions occur from time to time and liquefied natural gas is susceptible to explosion.

          * Natural gas burns completely and does not release conventional air pollutants and CO2 contributing to global climate change.

5. Explain renewable energy, mention various forms of the same and elaborate on its potential in Indian Scenario.

Renewable energy sources are sources that are continuously replenished by natural processes. For example, solar energy, wind energy, bio-energy - bio-fuels grown sustainably, hydropower etc., are some of the examples of renewable energy sources.

A renewable energy system converts the energy found in sunlight, wind, falling-water, sea-waves, geothermal heat, or biomass into a form, we can use such as heat or electricity. Most of the renewable energy comes either directly or indirectly from sun and wind and can never be exhausted, and therefore they are called renewable. 

Solar: India receives solar energy in the region of 5 to 7 kWh/m2 for 300 to 330 days in a year. This energy is sufficient to set up 20 MW solar power plant per square kilometre land area. 

Wind Energy : India has been rated as one of the most promising countries for wind power development, with an estimated potential of 20,000 MW. 

Biomass fuels account for about one-third of the total fuel used in the country. It is the most important fuel used in over 90% of the rural households and about 15% of the urban households. Using only local resources, namely cattle waste and other organic wastes, energy and manure are derived. Thus the biogas plants are the cheap sources of energy in rural areas.
 Cogeneration : Cogeneration improves viability and profitability of sugar industries. Indian sugar mills are rapidly turning to bagasse, the leftover of cane after it is crushed and its juice extracted, to generate electricity. This is mainly being done to clean up the environment, cut down power costs and earn additional revenue. According to current estimates, about 3500 MW of power can be generated from bagasse in the existing 430 sugar mills in the country. Around 270 MW of power has already been commissioned and more is under construction.