RENEWABLE ENERGY SOURCES

1. Supercapacitors (SCs) are energy storage devices that bridge the gap
between batteries and conventional capacitors. They can store more
energy than capacitors and supply it at higher power outputs than batteries
1. Explain in short flywheels and super capacitors as energy storage technologies.
Supercapacitors
Flywheel energy storage systems (FESS) employ kinetic energy stored in a rotating mass with very
low frictional losses. Electric energy input accelerates the mass to speed via an integrated motor-
generator. The energy is discharged by drawing down the kinetic energy using the same motor-generator.
Flywheel energy storage systems
Flywheel energy storage (FES) works by accelerating a rotor
(flywheel) to a very high speed and maintaining the energy in the
system as rotational energy. When energy is extracted from the
system, the flywheel's rotational speed is reduced as a
consequence of the principle of conservation of energy; adding
energy to the system correspondingly results in an increase in the
speed of the flywheel.
Prof.S.A.SHIMPLE Department of Mechanical Engineering, Shreeyash college of Engineering and Technology,Aurangabad.
95183645581

2. 3.What is fuel cell? Explain with simple sketch. Explain in short basic fuel cell operations.
Fuel cells work like batteries, but they do not run down or need recharging. They produce
electricity and heat as long as fuel is supplied. A fuel cell consists of two electrodes—a negative
electrode (or anode) and a positive electrode (or cathode)—sandwiched around an electrolyte
A fuel cell is used to produce the electrical current required to power various gadgets by converting
chemical energy into electrical energy. This is done when the fuel and the oxidizing agent undergo a series of
redox reactions, resulting in the production of electrons, water, carbon-di-oxide, and heat as by-products
fuel cell, any of a class of devices that convert the chemical energy of a fuel directly
into electricity by electrochemical reactions. A fuel cell resembles a battery in many
respects, but it can supply electrical energy over a much longer period of time. This is
because a fuel cell is continuously supplied with fuel and air (or oxygen) from an
external source, whereas a battery contains only a limited amount of fuel material
and oxidant that are depleted with use. For this reason fuel cells have been used for
decades in space probes, satellites, and manned spacecraft. Around the world
thousands of stationary fuel cell systems have been installed in utility power plants,
hospitals, schools, hotels, and office buildings for both primary and backup power;
many waste-treatment plants use fuel cell technology to generate power from the
methane gas produced by decomposing garbage
Prof.S.A.SHIMPLE Department of Mechanical Engineering, Shreeyash college of Engineering and Technology,Aurangabad.
95183645581

3. 4. Explain in short: Phosphoric acid fuel cell (PAFC),
Phosphoric acid fuel cells (PAFC) are a type of fuel cell that uses liquid phosphoric acid as an
electrolyte. They were the first fuel cells to be commercialized. Developed in the mid-1960s and field-
tested since the 1970s, they have improved significantly in stability, performance, and cost.
Phosphoric acid has many attractive properties as a fuel cell electrolyte such as (1)
stability, even at 200 °C; (2) low vapor pressure, although not negligible; (3) ability to use
air as the cathode reactant gas; and (4) tolerance to carbon monoxide (200 °C
operation).
The main disadvantages of this type of fuel cell are:
the low current density, low power generation, and long
startup time [19]. ... ... Main advantages of PAFC are:
achievable heating and power generation and low
sensitivity to fuel impurity
Prof.S.A.SHIMPLE Department of Mechanical Engineering, Shreeyash college of Engineering and Technology,Aurangabad.
95183645581

4. 5. Explain Polymer electrolyte membrane fuel cell (PEMFC),
In polymer electrolyte membrane (PEM) fuel cells, protons move through the electrolyte to the cathode
to combine with oxygen and electrons, producing water and heat. Polymer electrolyte membrane (PEM)
fuel cell uses a polymeric membrane as the electrolyte, with platinum electrodes
These cells operate at relatively low temperatures
These cells are the best candidates for cars, for buildings and smaller applications.
Polymer electrolyte membrane (PEM) fuel cells—also called proton exchange membrane
fuel cells—deliver high power density and offer the advantages of low weight and
volume, compared to other fuel cells. PEM fuel cells use a solid polymer as an electrolyte
and porous carbon electrodes containing a platinum catalyst.
They only hydrogen, oxygen from the air, and water to operate
and do not require corrosive fluids like some fuel cells. They are
typically fueled with pure hydrogen supplied from storage
tanks or onboard reformers
Prof.S.A.SHIMPLE Department of Mechanical Engineering, Shreeyash college of Engineering and Technology,Aurangabad.
95183645581

5. 5. Discuss in short various components of the fuel cell
A fuel cell consists of two electrodes—a negative electrode (or anode) and a positive electrode (or
cathode)—sandwiched around an electrolyte. A fuel, such as hydrogen, is fed to the anode, and air is fed to the
cathode.
Prof.S.A.SHIMPLE Department of Mechanical Engineering, Shreeyash college of Engineering and Technology,Aurangabad.
95183645581

6. There are three main components of a battery: two terminals made of different chemicals (typically metals), the
anode and the cathode; and the electrolyte, which separates these terminals. The electrolyte is a chemical
medium that allows the flow of electrical charge between the cathode and anode
The Anode is the negative or reducing electrode that releases
electrons to the external circuit and oxidizes during and
electrochemical reaction. The Cathode is the positive or
oxidizing electrode that acquires electrons from the external
circuit and is reduced during the electrochemical reaction
The anode is the component in which the x-radiation is produced. It is a relatively large piece of metal that connects
to the positive side of the electrical circuit. The anode has two primary functions: (1) to convert electronic energy
into x-radiation, and (2) to dissipate the heat created in the process.
6. Discuss in short various parts of the battery and their functions
•5 Key Functions Of An Automotive Battery. ...
•Engine starter. ...
•Helper to the ignition system. ...
•Sustainer. ...
•Alternator. ...
•Voltage regulator.
Prof.S.A.SHIMPLE Department of Mechanical Engineering, Shreeyash college of Engineering and Technology,Aurangabad.

7. The second type is rechargeable and
is called a secondary battery.
Examples of secondary batteries
include nickel-cadmium (NiCd), lead
acid, and lithium ion batteries.
Primary batteries are “single use” and
cannot be recharged. Dry cells and
(most) alkaline batteries are
examples of primary batteries.
7. Distinguish between primary and secondary batteries
primary batteries secondary batteries
Prof.S.A.SHIMPLE Department of Mechanical Engineering, Shreeyash college of Engineering and Technology,Aurangabad.
95183645581

8. Test methods range from taking a voltage reading, to measuring the internal resistance by a pulse or AC
impedance method, to coulomb counting, and to taking a snapshot of the chemical battery with Electrochemical
Impedance Spectroscopy (EIS)
8. With a schematic diagram explain the typical battery test process.
Battery Testing Procedure
1.Check the Container, Cover and Terminals. If physical
damage is present, replace the battery.
2.Check the Indicator (If the battery has the Indicator).
Always look right down when viewing the Indicator and
lightly tap the Indicator on the battery to dislodge any air
bubbles.
Prof.S.A.SHIMPLE Department of Mechanical Engineering, Shreeyash college of Engineering and Technology,Aurangabad.
95183645581

9. 9. What is the principle of fuel cell? Discuss problems associated with operation of fuel cell.
How Fuel Cells Work.
Fuel cells work like batteries, but they do not run down or need recharging. They produce electricity and heat
as long as fuel is supplied. A fuel cell consists of two electrodes—a negative electrode (or anode) and a positive
electrode (or cathode)—sandwiched around an electrolyte
A fuel cell is used to produce the electrical current required to
power various gadgets by converting chemical energy into
electrical energy. This is done when the fuel and the oxidizing
agent undergo a series of redox reactions, resulting in the
production of electrons, water, carbon-di-oxide, and heat as by-
products.
What is the problem with fuel cells?
The two prime dangers from fuel cell and hydrogen-powered vehicles are the danger of electrical shock
and the flammability of the fuel. Fuel cells power vehicles by electro-chemically combining hydrogen gas
(H2) and oxygen (O2) from the surrounding air into water (H20) and electrical energy
Prof.S.A.SHIMPLE Department of Mechanical Engineering, Shreeyash college of Engineering and Technology,Aurangabad.
95183645581

10. 10, What is geothermal energy? Give detailed classification of geothermal sources of energy
Geothermal energy is heat within the earth. The word geothermal comes from the Greek words geo (earth)
and therme (heat). Geothermal energy is a renewable energy source because heat is continuously produced
inside the earth. People use geothermal heat for bathing, to heat buildings, and to generate electricity.
Geothermal energy is a type of renewable energy taken
from the Earth's core. It comes from heat generated
during the original formation of the planet and the
radioactive decay of materials. This thermal energy is
stored in rocks and fluids in the centre of the earth.
Geothermal resources are reservoirs of hot water that
exist at varying temperatures and depths below the
Earth's surface.
Prof.S.A.SHIMPLE Department of Mechanical Engineering, Shreeyash college of Engineering and Technology,Aurangabad.
95183645581

11. 11. What are the advantages and disadvantages of geothermal energy over other forms of energy?
•Environmental issues. There is an abundance of
greenhouse gases below the surface of the earth. ...
•Surface instability (earthquakes) Construction of
geothermal power plants can affect the stability of land.
...
•Expensive. ...
•Location-specific. ...
•Sustainability issues.
Advantages disadvantages
Pros of geothermal energy Cons of geothermal energy
Reliable source of power Location dependent
Small land footprint High initial costs
Usable for large and small-scale
installations
Can lead to surface instability
The geothermal energy industry is
expanding
Prof.S.A.SHIMPLE Department of Mechanical Engineering, Shreeyash college of Engineering and Technology,Aurangabad.
95183645581

12. 12. What is biogas? Explain how it is renewable source of energy? What are the main problems
associated with biomass energy?
Biogas is an energy-rich gas produced by anaerobic decomposition or
thermochemical conversion of biomass. Biogas is composed mostly of
methane (CH4), the same compound in natural gas, and carbon dioxide (CO2).
Biomass energy is the use of biomass as an energy source. With biomass
energy, biomass is burned or converted to make heat, electricity, or liquid fuel.
Biogas is a renewable energy; it is created as a direct result of transforming food
waste to energy and it is an environmentally friendly way of doing it
Biogas is Eco-Friendly
Biogas is a renewable, as well as a clean, source of
energy. Gas generated through biodigestion is Biogas is a
renewable, as well as a clean, source of energy. Gas
generated through biodigestion is non-polluting; it actually
reduces greenhouse emissions (i.e. reduces the
greenhouse effect).
Prof.S.A.SHIMPLE Department of Mechanical Engineering, Shreeyash college of Engineering and Technology,Aurangabad.
95183645581