Power Plant Engineering

2.8.1 THE SUN
Sun is the source of many forms of energy available to us. The most abundant element in sun is
hydrogen. It is in a plasma state. This hydrogen at high temperature, high pressure and high density
undergoes nuclear fusion and hence releases an enormous amount of energy. This energy is emitted as
radiations of different forms in the electromagnetic spectrum. Out of these X-rays, gamma rays and most
of ultraviolet rays do not pass through the earth’s atmosphere. But heat energy and light energy are the
main radiations that reach the earth. This energy is the basis for the existence of life on earth.
Sun is a sphere of intensely hot gaseous matter with a diameter of 1.39e
9
m and 1.5e
11
m away
from earth. Sun has an effective black body temperature of 5762 K and has a temperature of 8e
6
K to
40e
6
K. The sun is a continuous fusion reactor in which hydrogen (4 protons) combines to form helium
(one He nucleus). The mass of the He nucleus is less than that of the four protons, mass having been lost
in the reaction and converted to energy. The energy received from the sun on a unit area perpendicular to
the direction of propagation of radiation outside atmosphere is called solar constant, and has a value
1353 Wm
– 2
. This radiation when received on the earth has a typical value of 1100 Wm
– 2
and is variable.

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NON-CONVENTIONAL ENERGY RESOURCES AND UTILISATION
39
The wavelength range is 0.29 to 2.5 micrometers. This energy is typically converted into usual energy
form through natural and man-made processes. Natural processes include wind and biomass. Man-made
processes include conversion into heat and electricity.
2.8.2 PETROLEUM
Petroleum products are by far the most versatile and useful energy resources available at present.
Their low costs until 1973, ease of transportation and infinite divisibility are the three attributes that
made petroleum products the most suitable and economical commercial energy resources. Petroleum
products constitute 50–95 percent of commercial energy supplies and almost all the needs of transporta-
tion sector and mobile equipment are currently met by petroleum products. There are only a few possi-
ble substitutes that too on a limited scale. They also constitute the basic fuel for electric power plants
while coal, natural gas and hydro resources are used in those locations where they are available. Kero-
sene and LPG are the favored cooking fuels and kerosene is the major lighting fuel in areas where there
is no electricity. Before going further, it is interesting to know a bit on the history of oil and its economic
and political implications in the past.
Petroleum was first found in Pennsylvania (USA). Petroleum is used to make gasoline, heating
oil, diesel fuel, and lubricating oils. Following is brief times on energy development:
1879: Standard oil controlled 90% of refining capacity.
1870–1880: Kerosene is the largest volume manufactured good.
1882: Standard Oil Trust was established, which was a shield of legality and flexibility. Edison
demonstrates electricity.
1885: 250,000 light bulbs in use.
1896: Henry Ford was the chief engineer at Edison, where he builds his first gasoline-powered
engine.
1900: 8,000 automobiles, Drilling began in Texas.
1905: Oil discoveries in Louisiana and Oklahoma.
1909: Standard Oil Trust was broken up in 38 companies.
1912: 902,000 automobiles in use
1913: Ford introduced the assembly line.
1928: Texas number one oil producer.
1938: Oil discovery in Kuwait and Saudi Arabia.
1940’s: United States shifts from petroleum exporting to petroleum importing.
1960: OPEC formed.
1986: Oil price collapse.
Petroleum is rock oil that exists down in the earths crust. They drill for petroleum to determine
the size of the reserve and to produce oil at a controlled rate. There are three steps in recovering petro-
leum. The first step is the primary recovery, which is when oil flows by natural pressure or simple
pumping. The maximum recovery is usually 30% of the oil available in the well. The next step is the
secondary recovery, which is when water or gas is pumped into the well to force oil out. This adds an
additional 10–20% to be recovered. The third step is the tertiary recovery, where hot gases and chemi-
cals are pumped into the well to make the oil less viscous for easier pumping. Petroleum is classified
according to its viscosity and sulfur contents. Pennsylvania’s crude oil is low in sulfur and viscosity,

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40
POWER PLANT ENGINEERING
Venezuela’s crude oil is high in sulfur and viscosity, and Middle East crude oil is usually low in sulfur.
Petroleum refining separates different components of petroleum. It changes the chemical composition
of petroleum component to produce desirable fuels and chemicals. Petroleum refining has 3 major proc-
esses. The first process is a physical process called distillation, which separates components according
to their boiling points. The second step is the cracking, which breaks down long chains to make more
gasoline, diesel, and jet fuel. This is a chemical process using a catalyst. The third process is the reform-
ing process, where it converts straight chains into branched chains for better performance in gasoline
engines. Petroleum is transported long distances by super tankers across oceans, and pipelines across
continents. For short distances, petroleum is transported by barges, trucks, and rail cars.
Petroleum products are used in internal combustion engines, where the fuel is put right into the
cylinder with the piston. A spark ignites the gasoline engines, and compression ignites diesel engines.