Q.24. Explain why Thermal Power stations are the
main source of pollution? (AKTU. - 2015 - 16)
Ans. The Thermal Power stations are the main source of pollution we can describe it through the following points -
Ans. The Thermal Power stations are the main source of pollution we can describe it through the following points -
- Thermal power generation is the main source of thermal pollution because its wastes have large amount of thermal energy. Other sources of thermal pollution are thermal electric power plants, petroleum industry, nuclear power plants, steel industries, pulp and paper processing industries, distillery industries etc.
- Carbon dioxide produced during the combustion of fuel in power plant is the main source of pollution.
- The other sources of pollution are boiler blow downs, waste water from coal storage, run-off from coal handling and coal preparation yards.
Q.25. Describe “Renewable
energy resources” with two examples and diagram. (AKTU. - 2015 - 16) Ans. Renewable
energy is generally defined as energy that is collected from resources which
are naturally replenished on a human timescale, such as sunlight, wind, rain,
tides, waves, and geothermal heat. Renewable energy often provides energy in
four important areas: electricity generation, air and water heating/cooling,
transportation, and rural (off-grid) energy services.
Based on REN21's 2016 report,
renewables contributed 19.2% to humans' global energy consumption and 23.7% to
their generation of electricity in 2014 and 2015, respectively. This energy
consumption is divided as 8.9% coming from traditional biomass, 4.2% as heat
energy (modern biomass, geothermal and solar heat), 3.9% hydro electricity and
2.2% is electricity from wind, solar, geothermal, and biomass. Worldwide investments
in renewable technologies amounted to more than US$286 billion in 2015, with
countries like China and the United States heavily investing in wind, hydro,
solar and biofuels. Globally, there are an estimated 7.7 million jobs
associated with the renewable energy industries, with solar photovoltaics being
the largest renewable employer.
Renewable energy resources exist
over wide geographical areas, in contrast to other energy sources, which are
concentrated in a limited number of countries. Rapid deployment of renewable
energy and energy efficiency is resulting in significant energy security,
climate change mitigation, and economic benefits. The results of a recent
review of the literature concluded that as greenhouse gas (GHG) emitters begin
to be held liable for damages resulting from GHG emissions resulting in climate
change, a high value for liability mitigation would provide powerful incentives
for deployment of renewable energy technologies.
Wind
Power: -
Airflows can be used to run wind turbines. Modern utility-scale wind
turbines range from around 600 kW to 5 MW of rated power, although turbines
with rated output of 1.5–3 MW have become the most common for commercial use;
the power available from the wind is a function of the cube of the wind speed,
so as wind speed increases, power
output increases up to the maximum output for the particular turbine. Areas
where winds are stronger and more constant, such as offshore and high altitude
sites, are preferred locations for wind farms. Typically full load hours of
wind turbines vary between 16 and 57 percent annually, but might be higher in
particularly favorable offshore sites.
Globally, the long-term technical
potential of wind energy is believed to be five times total current global
energy production, or 40 times current electricity demand, assuming all
practical barriers needed were overcome. This would require wind turbines to be
installed over large areas, particularly in areas of higher wind resources,
such as offshore. As offshore wind speeds average ~90% greater than that of
land, so offshore resources can contribute substantially more energy than land
stationed turbines. In 2014 global wind generation was 706 terawatt-hours or 3%
of the worlds total electricity.
Hydro
power: -
In 2015 hydropower generated 16.6% of the worlds total electricity and
70% of all renewable electricity. Since water is about 800 times denser than
air, even a slow flowing stream of water, or moderate sea swell, can yield
considerable amounts of energy. There are many forms of water energy:
Historically hydroelectric power
came from constructing large hydroelectric dams and reservoirs, which are still
popular in third world countries. The largest of which is the Three Gorges
Dam(2003) in China and the Itaipu Dam(1984) built by Brazil and Paraguay.
Small
hydro systems are hydroelectric power installations that typically produce up
to 50 MW of power. They are often used on small rivers or as a low impact
development on larger rivers. China is the largest producer of hydroelectricity
in the world and has more than 45,000 small hydro installations.
Run-of-the-river
hydroelectricity plants derive kinetic energy from rivers without the creation
of a large reservoir. This style of generation may still produce a large amount
of electricity, such as the Chief Joseph Dam on the Columbia river in the
United States.
Hydropower is produced in 150
countries, with the Asia-Pacific region generating 32 percent of global
hydropower in 2010. For counties having the largest percentage of electricity
from renewables, the top 50 are primarily hydroelectric. China is the largest
hydroelectricity producer, with 721 terawatt-hours of production in 2010,
representing around 17 percent of domestic electricity use. There are now three
hydroelectricity stations larger than 10 GW: the Three Gorges Dam in China,
Itaipu Dam across the Brazil/Paraguay border, and Guri Dam in Venezuela.
Wave power, which captures the energy of ocean
surface waves, and tidal power, converting the energy of tides, are two forms
of hydropower with future potential; however, they are not yet widely employed
commercially. A demonstration project operated by the Ocean Renewable Power
Company on the coast of Maine, and connected to the grid, harnesses tidal power
from the Bay of Fundy, location of world's highest tidal flow. Ocean thermal
energy conversion, which uses the temperature difference between cooler deep
and warmer surface waters, has currently no economic feasibility.
