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[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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16ME320 – RENEWABLE ENERGY UTILIZATION
Two mark Important questions & Answers
Unit 1
1. Discuss world energy use
world energy consumption for electricity generation by source was coal at 41%,
natural gas at 22%, nuclear at 11%, hydro at 16%, other sources (solar, wind, geothermal,
biomass, etc.) at 6% and oil at 4%. Coal and natural gas were the most used energy fuels
for generating electricity.
2.Define Reserves
"Reserves" represent that portion of demonstrated resources that can be recovered
economically with the application of extraction technology available currently or in the
foreseeable future. Reserves include only recoverable energy
3. Contrast the environmental aspects
All energy sources have some impact on our environment. Fossil fuels—coal, oil, and
natural gas—do substantially more harm than renewable energy sources by most measures,
including air and water pollution, damage to public health, wildlife and habitat loss, water
use, land use, and global warming emissions
4.what is the energy scenario of tamilnadu
Tamilnadu has highest installed renewable energy capacity (7,979 MW by Sep 12, TEDA)
in India. Renewable energy contributes 52% of the total installed capacity of the state. ...
Tamilnadu has the highest growth rate for the wind installation with CAGR of 15% over the
period of five years from FY 2007 to FY 2012
5.Infer the economics of renewable energy
The economics of renewables is about profitability, and profitability depends on three
drivers: (1) the market price or value of renewable electricity; (2) the costs of renewables
SNS COLLEGE OF TECHNOLOGY
COIMBATORE-35
DEPARTMENT OF MECHANICAL ENGINEERING
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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relative to those of other energy resources; and (3), importantly, policies to promote
renewables and environmental goals
6.List the energy conservation methods
Lighting. ...
Turn off and run equipment only when required. ...
Clean and maintain equipment. ...
Shade windows and walls. ...
Replace existing lights with LED. ...
Use natural airflow. ...
Check air conditioning lines. ...
Optimise appliances.
7. List three non – conventional energy sources of electric energy in India
Currently, some of the important and widely used non conventional sources of energy are
tides, wind, solar geothermal heat, and biomass comprising animal waste, agricultural waste,
and human body waste
8. Mention the present contribution of different types of plants in India
More than 65% of India's electricity generation capacity comes from thermal power plants,
with 85% of the country's thermal power generation being coal-based. The ten biggest
thermal power stations operating in India are all coal-fired, with five of them owned and
operated by state-run National Thermal Power Corporation (NTPC). Power-technology.com
profiles India's ten biggest thermal power plants by installed capacity.
9.What is the approximate amount of total power generation in India
The country's installed power generating capacity of 334.4 gigawatt (GW, or 1,000
megawatts) as of January 2018 is the world's fifth-largest. Over the last five years, India put
up 99.21 GW of additional capacity. Of this, 91.73 GW came from thermal sources, 5.48 GW
from hydro, and 2 GW from nuclear sources
10.Explain about renewable resources
These are capable of being regenerated by ecological processes within reasonable period.
Theyhave potential torenew themselves.Examples: solar, water,wildlife, natural
vegetation.These are furthersub classified into two types such as
i)Continuousresources:continuouslyrenewedresources.(Solarenergy,wind, tidal
energy)ii)Extrinsicresources:resourcesarepronetobreakdownordegradation,yet are
continuously if wellmanaged. (Human skills, institutions, management abilities)
11.What arefive basiccauses of environmental problems?
Unsustainable resource, Rapid population growth, Poverty, Neglecting environmental costs in
production, Lack ofawareness in ecosystems.
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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12.Define pollution?
Pollutionisdefinedasexcessivedischargeofundesirablesubstancestothe
environment,adverselyalteringthenaturalqualityoftheenvironmentandcausing damage to
biomass, plants and animals.
13. Describeair pollution and statethe classifications of airpollutants
Theairpollutionwhichoccursinthetropospherelevelismainlyduetothe
industriesandvehicles,suchapollutedairaffectsvegetation,promotescorrosion, blocks out
sunlightand
deteriorationofrubber,paints,etc.,.Therearetwotypesprimarypollutantsreleasedintotheairinitsori
ginalform (CO,NO,SO2,etc.,)andwhilesecondarypollutantsbecomesubsequenttoreactions
intheairtoformnewpollutants(Ozone,SO2,Aldehydes,Ketones,Peroxyacyl nitrate, etc.,).
14. What are the sources ofairpollution
?Thenaturalsources(volcaniceruptions,forestfires,biologicaldecay,sources
ofradioactivityinatmosphere)andmanmadesources(Anthropogenic)suchasfossil fuel burning,
vehicular emissions, power plants,agricultural activities, etc.
15. What are organic pollutants?
They are polychlorinatedbiphenylandDDT(DichloroDiphenylTrichloroethane, a pesticide).
16.What meant by carbon monoxide?
It is colorless, odorless flammable gas which is a product of incomplete combustion.6. What
are the sources of Sulphur dioxide?The sourcesofSO2are fromthe industries and manmade
activities.
Unit 2
1. Enumerate Reflection losses.
Some of the incident radiation is lost through the reflection from the surface of the cell and
the material used to protect them from weather. The loss due to reflection in an antireflective-
coated cell is between 5 and 10%
2. What is incomplete absorption?
Photons with less energy than the energy gap Eg will simply generate heat in the cell. The
higher the energy gap, the greater the wastage.
3. What i s Partial utilization of photon energy explain?.
Many of the photons which generate electron hole pairs have more energy than is needed for
this operation. The excess energy is dissipated as heat . Thus the higher the energy gap, the
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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smaller the wastage. Taking into account for second and third loss factors, it follows that a
semiconductor with an energy gap of 0.9 eV would be best adopted for the AMO spectrum
4. State Collection losses
Only those carriers reach the junction before recombining are collected and contribute to the
output current while others simply generate heat. This collection efficiency is the ratio of the
actual short circuit current density and the short circuit current density which would be
obtaining in the case of no recombination.
5. List Factors affecting collecting efficiency
1. The absorption characteristics of the semiconductor determines the geometrical
distribution of the generated electron-hole pairs in the crystal
2. The junction depth
3. The width of the depletion layer
4. The rate at which electron and holes combine at surface
5. The average distance an electron will travel in the p-region and the hole in the n-
region before recombining
6. The existence and strength of any inbuilt electric fields resulting from impurity
concentration gradients in the surface and base regions which help to accelerate
carriers towards the junction.
7. What are Voltage factors, explain?
The open-circuit voltage is always less than energy gap for the following reasons:
An open circuit voltage equal to the potential of the electric field at the junction can be
obtained only at extremely high inputs which can be attained by unconcentrated sunlight
Due to doping ,the barrier height is always less than the energy band gap
8. State Absorption length.
The average distance that travels into a material before about 63% of it is absorbed is called
the absorption length of that material
9. Define Diffusion.
The average distance that light generated minority carriers can move towards the built-in-
field before they drop back into fixed state is called the diffusion length
10. Write importance of Photovoltaic materials?
The choice between higher efficiency and lower fabrication cost often boils down to a choice
between crystalline and thin film materials. Crystalline devices are more efficient but thin
film devices cost less. Many materials are being investigated with emphasis on crystalline
Silicon, amorphous silicon, Polycrystalline thin films and III-V single crystal materials
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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11. Write few PV applications?
Photovoltaic devices have been around doing exotic things like generating electricity for
satellite in space. But the real value of PV lies in its potential to produce electricity on earth
and to do so cheaply enough to complete with conventional sources of electricity like nuclear,
coal, oil and natural gas.
12. How PV is Communicated
PV is also used for powering systems that provide communication in remote locations. Many
such applications are for transmitters on hill tops or mountains, where PV with battery
storage has clear advantages over systems that require fuelling or maintenance
13. Explain Warning signals
Systems to provide warning signals in isolated areas are another natural use of PV and one of
the largest existing PV markets
14. Remote monitoring means what?
Small PV systems, most under 200W are being used in remote locations for maintaining
various phenomena. In all the cases, there is battery backup and details of uses are as follows
Pollution data
Seismic record
Weather and climatic information
Highway conditions
15. State Physics of the sun
The sun has an effective black body temperature of 5762 K. The temperature in the central
interior regions is estimated at 8 x 106 to 40 x 106 K and the density at about 100 times that of
water.
16. Define Solar constant
The eccentricity of the earth’s orbit is such that the distance between the sun and the earth
varies by 1.7%. At a distance of one astronomical unit 1.495 x1011 m, the mean earth-sun
distance , the sun subtends an angle of 32’.
17. State Beam radiation
The solar radiation received from the sun without having been scattered by the atmosphere.
Beam radiation is often referred to as direct solar radiation.
18. Define Diffuse radiation
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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The solar radiation received from the sun after its direction has been changed by scattering by
atmosphere. Diffuse radiation is referred to some meteorological literature as sky radiation or
solar sky radiation.
19. Define Global radiation
The total solar radiation (sum of beam and diffuse radiation) on horizontal surface is often
referred to as global radiation
20. Irradiance means what ?
W/m2. The rate at which radiant energy is incident in per unit area of surface
Irradiation J/m2.
The incident energy per unit area on a surface found by integration of irradiance over a
specified time, usually an hour or day. H is used for isolation for a day and I is used for
isolation for an hour.
Solar time
It is the time based on the apparent angular motion of the sun across the sky, with solar noon
the time the sun crosses the meridian of the observer. Solar times does not coincide with the
local tome clock. It is necessary to convert standard time to solar time by applying the
following corrections
Solar time = standard time + 4(Lst – Lloc) + E
21. What do you mean byAir mass (m)
Air mass is the ratio of the optical thickness of the atmosphere through which the beam
radiation passes to the optical thickness if the sun were at zenith angle subtended by a vertical
line to the zenith.
22. Enumerate Measurements of solar radiation.
Short wave radiation
Radiation originating from the sun, in the wavelength range of 0.3 to 3.0 µm
Long wave radiation
Radiation originating from sources at temperature near ordinary ambient temperatures
and thus all at wavelengths greater than 3 µm
23. What is Pyrheliometer?
An instrument for measuring solar radiation from the sun and from a small portion of the sky
around the sun at normal incidence.
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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24. What is Pyranometer
An instrument for measuring total hemispherical solar radiation, usually on a horizontal
surface.
25. Sunshine recorder used for.
Sunshine recorder is used to measure hours of bright sunshine.
26. Solar radiation data used for.
1. Instantaneous measurements or values integrated over some period of time
2. The time or time period of measurements
3. The measurements of beam, diffuse or total radiation and the instruments used
4. The period over which they are averaged
5. The receiving surface orientation
6. 26.What is Solar drying
Solar drying is a traditional method for preserving food. The drying process removes the
moisture and helps in the preservation of the product.
27. Enumerate solar desalination
Solar energy can be used for providing drinking water. By using an equipment known as
“Solar Still” the saline or impure water can be desalinated using solar water.
28. How Solar cooker works
Solar cooker does not require any type of fuel like dung,wood, coal , kerosene etc., It works
only on solar energy.
29.Why Black coatings are needed?
In order to convert solar radiation falling on the absorber system into heat the absorber has to
be coated with black coloured paints or other similar materials
30.What is Collector glazing
A transparent cover over the absorber of the collector has the function of allowing the solar
radiation to pass through it and act as an opaque certain to the radiation emitted by the hot
absorber
31. Transmission through glass cover means
A clean sheet of ordinary window glass transmits about 84% of the energy incident on glass
surface.
32. Transmission through plastic covers mweans
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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Some of the plastics such as clear acrylic, PVC and GRP are capable of transmitting as much
or even more energy than glass.
33.Define Double glazing.
Two layers of glass are sometimes used in order to reduce the heat losses from the absorber.
34.Factors considered for Collector designs
a) Built in channels
b) Tubes bonded on the blackened surface of the absorber sheet
c) Tubes bonded on the exposed surface of the absorber sheet
d) Tubes fitted in grooves
e) Corrugated sheet fixed on flat sheet
f) Both sides corrugated sheets
g) Hexagonal channels etc.,
35.What are Collector energy losses
Solar radiation in the collector is uniform and steady
Collector performance is in steady state condition
Absorber plate and transparent covers are at uniform temperatures.
Energy loss upward through the transparent covers is one dimensional
Energy loss downward through the bottom insulation is two dimensional
Energy loss sideways through the edge insulation is one dimensional around the perimeter of
the collector
36..Explain Performance of Solar Cell
Reflection of some power at the cell surface
Absorption resulting in the generation of electron-hole pairs and parasitic absorption
resulting in production of heat. A part of sunlight is not absorbed and is transmitted
through the cell.
Separation and collection of photo generated carriers
Flow of carriers towards the external contacts.
Dissipation of the photo generated power in an external load
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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UNIT 3
1. Define Wind energy:
Wind energy is an indirect energy from of solar. About 1 percent of total solar
radiation that reaches the earth is converted in the atmosphere into the energy of the wind.
2. Write Wind energy technology Equation
The kinetic energy, u, of a sample volume, A(δx), and densityῤ, moving with
velosityὐ, where A is a unit area perpendicular to the wind stream and δx is parallel to the
wind stream, is:
3. State the influence of Aerodynamics
Modern wind turbines extract energy from the wind stream by transforming the winds
linear kinetic energy to the rotational motion needed to turn an electrical generator. This
change is accomplished by a rotor which has one , two or three blades or airfoils attached to a
hub, wind flowing over the surfaces of these airfoils generates the forces that cause the rotor
to run.
4. Principle of wind energy conversion:
When wind is blowing it exerts two types of forces , lift and drag on the object in its
path. Drag force acts in the same direction as the wind while lift force is perpendicular to the
direction of the wind.
5. Rotor design means
In order to understand the effect of difference in rotor design it is useful to describe
how the blades of a rotor react to the wind, and to define some of the standard design
parameters.
6. What is Pitch
The lift force created cause the rotor to rotate. In order to generate the max amount of
lift, the blades must be set at an appropriate angle to the wind.
7. Solidify means what
This is usually defined as the percentage of the circumference of the rotor which is
filled by the rotor blades.
8. What is Tip-speed ratio?
This is the ratio of the speed of the blades tips to the speed of the wind
9. State Performance coefficient:
The performance coefficient of a rotor is the friction of wind energy passing through
the rotor disc which is converted into shaft power. This is measure of the efficiency of
the rotor and it varies with the tip-speed ratio.
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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10. What is Torque:
Torque is the turning force produced by the rotor. It depends on thesolidify and tip-
speed ratio of the rotor.
11. What is various designs of rotors
Two or three –bladed horizontal axis wind mills are used for electricity generation
they are not suitable for water pumping because
1. They can not produce enough torque to start the piston pump working
2. They rotate too quickly to directly drive a reciprocating pump. This too
difficult manufacturing
3.
12. List the parameters to chose Site elevation:
The following parameter should be measured
1. Avg annual wind speed
2. Avg monthly wind speed for each month
3. Typical diurnal wind speed pattern for each month
4. Length and annual distribution of lull periods
13. How Wind measurement made
Various option available for taking wind measurement depending on the time
available, budget available and accuracy required.
14. How Quality of wind data is measured:
Until quite recently there was little standardisation of wind data collection except at
major airports where data has had to be collected in an internationally agreed manner.
15. State wind turbines in WE
there are two fundamentally different types of wind turbines. The first is the
horizontal axis wind turbine, which has the axis of rotation to the parallel to the wind
stream
16. What is wind stream system:
a modern HAWT is composed of several sub system
1. The rotor, which consist of one two three blades mounted on a hub and may
include aerodynamic braking system 2.The yaw system which potions the
rotor perpendicular to the wind stream ,3.the tower , 4.Balance of station
system including roads ground support equipment and interconnection
equipment.
17. What is rotor in WE?
The rotor, which converts the winds kinetic energy into the kinetic energy rotation.
18. Explain Drive trains:
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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The major component of drive train are the low and high speed shafts, the mechanical
braking system, bearing, coupling, gearbox or transmission, and nacelle.
19. State Yaw-control system:
Horizontal axis wind turbines fall into two categories: upwind machines or down
wind machines. Yaw systems are used to orient the plane of the rotor perpendicular to
the wind stream
20. Explain Wind energy utilization:
Small windmills with direct mechanical drive matched to a pump and storage tank,
are now in extensive use in many parts of the world including India. Wind energy is
high quality form of mechanical energy that can be converted into electrical energy
with minimum loss
21. Explain Origin of tides:
Tide are created by the gravitational attraction of the moon and sun acting on the
ocean of the rotating earth
22. State Tidal barrage design:
A modern tidal energy scheme consists of a barrage or a dam that is constructed
across an estuary and is equipped with a series of gated sluices to permit entry of
water to basin
23. In tide barrage what are the Modes of operation:
A tidal barrage can be operated one of three different modes:
Ebb generation Flood generation Two way generation
24. State Wave energy:
Ocean wave are created by the interaction of the winds with the surface of the sea
25. What are Terminators?
We get max energy when several devices are mounted on a linear spine oriented at 90
degree to the wave direction known as terminator mode.
26. What are Attenuators?
In attenuators mode, the device is parallel to the wave direction.
27. What tare the factors determine the o/p from a wind energy converter
1. The wind speed 2. The cross section of wind swept by rotor
3. The overall conversion efficiency of the rotor transmission system and generator or
pump.
28. Define isodynes
They are contours of constant wind popwer again it is important to know the averaging
period
29. Explain wind survey?
a.Instrumentation b.Data recording system c.Types of data d.Data reporting
30. What is aero turbine?
Aero turbines convert energy in moving air to rotary mechanical energy..In general they
require pitch control and yaw control.
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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UNIT 4
1.Explain The Process Of Photosynthesis?
In the process of Photosynthesis, sunlight is absorbed by chlorophyll in the
chloroplasts of green plant cells and utilized by the plant to produce carbohydrates from
water (H2O) and carbon dioxide(CO2) taken from the atmosphere.
6CO2+6H2O sunlight C6H12O6+6O2
2. What Is Bio Mass Production Efficiency?
It is the efficiency of converting incident solar energy in to the chemical energy
stored in carbohydrates in plants.
3. Write Any One Implication Of Rising CO2 Levels On Bio Mass Production.
The concentration of CO2 would increase relative to CO2 Photorespiration would be reduced
in favor of Photosynthesis.
4. Mention The Three Aspects Of Bio Mass Resources Development.
Detailed characterization of the soil properties. Growth
measurements and
Energy values of the test species
5. Write The Application Of Bio Mass Conversion.
Direct combustion ,Gasification, Cogeneration
6. Explain the types of Gasifier.
Fixed bed updraft gasifier.Fixed bed down draft
gasifier.Cross draft gasifier.Fluidized bed gasifier.
7. Advantage OfGasifier Design.
It is suitable for many biomass fuels. It can gasify wet fuel
and does not require any specific fuel size. Lower value of water decomposition
and thermal efficiency is higher.
8. Explain the Fixed Bed Down Draft Gasifier.
The fixed bed down draft gasifieris similar to the updraft design except that the
process air is introduced at or above the combustion zone, exiting near the bottom of the
chamber.
9. Explain the Cross Draft Gasifier.
It is very compact gasifier and is highly suitable for small power outputs. This Gasifier is also
good for changing loads.
10. Explain The Fluidised Bed Gasifier.
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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The Fluidised Bed Gasifier have been developed which promise greater capacity and gas
production rates than fixed bed type.
11. Benefits of bio gas technology.
It generates many social benefits such as reduction in the cutting in the cutting trees for
fuelwood, reduction in the drudgery of women and children, improvement in sanitation and
environment, reduction in the incidence of eye and lung diseases, and greater availability of
time for productive employment.
12. What is the family based plants.
There are two well tested and field-worthy designs of biogas plants. They are (i) floating gas
holder type)(KVIC type gobar gas plant). (ii) Fixed dome type (Janata biogas plant).
13. Technical Problems and constraints of biogas.
Problems caused due to modification brought in the design specification at the local level.
Seasonal variation in gas production due to lack of temperature control and poor
insulation of the plant.Inefficient designing of gas applications.
14. Socio-economic problems and constraints of biogas.
Socio-economic problems which can slow down the progress of the program are as under:
Installation of over-size plants simply due to a symbol of social prestige.Lack of
awareness due to illiteracy.Lack of financial resources or capacity to borrow loans
from financing institutions
15. What are the problems raised due to biogas for the different stages of lifecycle.
The following problems crop up from time to time:
i. Defective construction by untrained or improperly trained
masons
ii. Lack of strict supervision in training courses
iii. Delayed supply of raw materials and plant components
iv. Lack of coordination among various agencies
16. List the methods of converting biomass into useful forms of energy.
Bio chemical and, Thermochemical
17. Write the Advantages of gasifiers.
It is very easy to operate the gasifier.Its maintenance is easy.It is sturdy in construction and,
It is reliable in operation.
18. Write the direct thermal applications.
Cement manufacture, Glassmaking, Brickmaking, Ceramics and pottery, Rubbermanufacture,
Fertilizer production.
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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19. Write the classification of biogas plant.
Bio gas plants mainly classified as following types
Continuous and batch types.The dome and the drum types.Different variations in the drum
type.
20. Factors affecting the bio digestion or generation of gas.
The following factors that affect the generation of gas
PH or the hydrogen-ion concentration.Temperature.Total solid content of the feed material
loading rat
Unit V
1) What is fuel cell?
Fuel cell comprises two electrochemical conducting electrode separated by an electrolyte.
the fuel is fed outside of one electrode and air or oxygen is supplied from outside of other
terminal.
2) What is Chemical polarization?
It is a surface phenomena and the magnitude of which depends in part upon how ions
are discharged at the electrodes and in part upon the rate at which they are discharged.
3) What is Concentration polarization?
In a electrochemical cell, there is a loss of potential due to the inability of the surrounding
material to maintain the initial concentration of the bulb fluid after currents begins to flow.
4) What are the methods involved in Production of hydrogen?
The following methods are generally considered for the production of hydrogen
1. Electrolysis of water
2. Thermal decomposition of water
3. Thermo chemical methods
5) Enumerate Hydrogen as alternative fuels
Hydrogen is a secondary energy carrier just as electricity. Thus the primary energy
(nuclear, solar, hydro or even fossil) is needed for its production. The introduction of
Hydrogen as an energy source on a sizeable scale involves 5 basic issues.
1. Production
2. Storage and transport
3. Usage of Hydrogen as energy source
4. Safety
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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5. Economics and management.
6) Advantage in Hydrogen storage?
1. Its spectrum of applications must be of high importance for the energy market and its
usage must be as clean as possible;
2. Its transport or transmission should be feasible at low coats;
3. Its storage should be technically and economically feasible
7) Classifications of Hydrogen storage and systems?
1. Stationary large storage system
2. Stationary small storage system
3. Mobile storage systems for transport and distribution
4. Automobile fuel reservoirs
8) What is stationary large storage system?
These storage systems are typically located at the production sites, and at the terminals
of pipelines and other transportation paths. They typically include, besides the storage
capacity related components like the reservoir, also a power consuming system component i.e
machinery or plant such as compressors and liquefiers. Accordingly the corresponding costs
may include significant power dependent capital costs and energy cost components.
9) What is stationary small storage system?
They are most used for intermediate storage, for ex, at industrial sites. Here, normally
only capacity related costs are relevant.
10) What are mobile storage systems for transport and distribution?
These include bulk carriers like liquid hydrogen tankers, or similar smaller systems like
as LH2 and gas truck trailers. Cost components here include capacity dependent investment
costs and operational costs.
11) What is an Automobile fuel reservoir?
These are the tanks used for the onboard storage of hydrogen used as fuel for road
vehicles. For hydrogen powered vehicles the tank weight needed by some hydrogen storage
methods may give rise to the excessive fuel consumption. The operating costs also on the on
broad storage method and vehicle range.
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12) Explain about underground hydrogen storage?
Future hydrogen supply systems will have a structure similar to those of today’s natural
gas supply systems, where underground hydrogen storage has been shown to be feasible. Spl
technical problems for the case of pure hydrogen are manageable. So far a gas cavern has
been used since 1971 in kiel to store town gas with a content of upto 65% hydrogen at
pressure of about 180 bar. Underground hydrogen storage is of special importance for
stationary large scale storage systems
13) List Types of polarization?
1. Chemical polarization
2. Concentration polarization
3. Resistance polarization
15) List various types of fuel cells?
1. Hydrogen oxygen fuel cell
2. Bio chemical cells
3. Regenerative cells
16) What is Regenerative cell
1. Thermally regenerative cells are medium efficiency devices (5 to 20 %) with
proven cell life times of up to 12000 hours.
2. In air cooled systems, the regenerative size will depend primarily on the
condenser to air heat transfer co efficient.
17) What are Bio chemical cells?
In bio chemical cell one or both electrode reaction are promoted or catalyzed by
biological process. Biochemical cells can be divided into two types.
18) Types of bio chemical cells?
1. Indirect cell 2. Direct cell
19) List the Elements of fuel cell?
a) electrolyte
b) Load
c) Oxidizer
d) Fuel
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20) Write the Fundamentals of electrochemistry?
Fuel cells operate on the principles of electrochemistry and so we consider Daniel
cell which consists of load variation and container divided into two parts by a partition that
permits the diffusion of ions b/w them.in the left hand compartment which contains zinc
sulphate, we complete the circuit by connecting the two electrodes by a wire that can deliver
current to an external load.
21) What are the Type of fuel cells.
1) Hydrogen fuel cell
2) Hydrazine fuel cell
3) Hydrocarbon fuel cell
4) Alcohol fuel cell
22) What are the main components of the fuel cells.
A fuel electrode (anode)
An oxidant or air electrode(cathode)
An electrolyte.
23) Explain two types of hydrogen cells
Low temperature cells: The electrolyte temp is 90 c. it is sometimes pressurized but not
by great amount usually say up to 4 atmospheres. High pressure cells: pressure is up to about
45 atmosphere and temperature up to 300◦C
24) Classification of fuel cells according to the temperature range.
Fuel cells may be classified a according to the temperature range:
Low temperature : 25-100◦C
Medium temperature : 100 500◦C
High temperature : 500-1000◦C
Very High temperature : above 1000◦C
25) Classify the fuel cell according to to the physical state of the fuel.
Gas-hydrogen, lower hydro carbon
Liquid-alcohol, hydrazine, higher hydro carbon.
Solid-metal etc.
26) Desired properties of an ideal ion exchange membrane electrolyte are:
High ionic conductivity
Zero electronic conductivity
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Low degree of electro –osmosis.
Mechanical stability.
27) Advantage and Dis advantage of fuel cells.
The fuels take little time to go into operation.
As fuel cells do not make noise, they can be readily accepted in residential
areas.
28) Define conversion Efficiency of fuel cells.
The electrical energy generated by fuel cells depends on what is called the free energy
rather than on the heat energy of overall cell reaction.
29) What is polarization?
In a practical fuel cell the theoretical output voltage is not attained for several reason as
outline below and the difference b/w the theoretical voltage and the actual voltage.
30) what are the main type of polarization.
Active polarization
Resistance or ohmic polarization
Concentration polarization.
31) What are Types of electrode and explain.
Porous electrode & Non Porous electrode.
Porous electrode: the design of these electrodes has been based on the assumption
that is necessary to maintain a three phase boundary b/w gas, electrode and electrolyte.
Non Porous electrode: the concept of Non Porous electrode diffusion membrane
electrode and the problems of interface control and of direct chemical reaction with the
electrolyte.
32) List the Application of fuel cell.
Domestic use
Central power station
Automotive vehicle &
Special application.
33) Explain the hydrogen in the near future .
Direct use of hydrogen as an aircraft fuel in air transport.
Use of hydrogen in the processing of heavy oil.
[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT
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34) What is electrolysis?
The process of splitting water into hydrogen and oxygen by means of direct electric
current .
35) What is electrolyte?
An electrolysis cell consists of two electrodes commonly flat metal or carbon plate
immersed in an aqueous conducting solution.
36) Advantage and Dis advantage of electrolyze.
Advantage: two-fold relatively few parts are required and those needed are relatively
inexpensive and individual cell may be isolated for repair or re placement simply by short
circuiting the two abject cells with temporary bus bar connection.
Dis advantage: inability to handle high current densities because of cheaper component parts.
37) Principle of hydrogen storage.
Compressed gas storage
Liquid storage
Line pack system
Under ground storage
38) Types of transport.
Hydrogen transport
Liquid Hydrogen transport
Metal Hydride transport
39) Advantage of claimed hydrogen fuel engine
They are higher efficiencies.
The amount carbon monoxide and hydrocarbon in the exhaust should be very
small.
40) What is the future scope of hydrogen?
It is unlikely that hydrogen would serve as a major fuel for electric power generation
by utility. Hydrogen could also be used for storing and distributing electrical energy.