Explanation for the types of energy conversion

1. UNIT - I
Nanotechnology in Energy
conversion and storage
A. Periyanayaga Kristy
Ph.D. Research Scholar
SRM University
Chennai

2. Sustainable electricity storage
• sustainability is defined: as “meeting the needs of the present without
compromising the ability of future generations to meet their own needs.”
• sustainable energy: is energy that meets the needs of the present
generations without compromising the ability of future generations to meet
their own needs.
• Sustainable energy is about finding clean, renewable sources of energy—
sources that renew themselves, rather than sources that can be depleted.
• Two ways:
• Rechargeable batteries
• Supercapacitors

3. Rechargeable batteries
• Compared with the aqueous batteries, the Li-ion chemistry leads to an
increase of 100–150% on storage capability of energy per unit weight and
volume.
• Nevertheless, some disadvantages arise, related to low energy and power
density, large volume change on reaction, safety and costs.
• The aforesaid shortcomings can be reduced (or are being reduced) by the
application of nanotechnology to the field of rechargeable batteries.
• Actively research in nanobatteries points out the use of nanomaterials for
both the electrodes and the non-aqueous electrolyte.

4. Rechargeable batteries
• There is a general consensus on the key role that nanotechnology plays for
future battery applications and its market adoption. The main achievements
pointed out by the authors are listed below.
• Electrolyte conductivity increases up to six times by introducing nanoparticles
of alumina, silicon or zirconium to non-aqueous liquid electrolytes.
• Most efforts have been focused on solid state electrolytes, solid polymer
electrolytes (SPE).
• Poly(ethylene oxide)-based (PEO-based) SPE received most attention since
PEO is safe, green and lead to flexible films.
• Nevertheless, polymers usually have low conductivity at room temperature
and, depending on SPE compositions, their interfacial activity and mechanical
stability are not high enough.
• In this sense, nanocomposite polymer electrolytes could help in the fabrication
of highly efficient, safe and green batteries.

5. Supercapacitors
• Electrochemical capacitors (ECs), also named supercapacitors and
ultracapacitors, store electrical energy, like batteries, but using a different
mechanism.
• While batteries do it chemically, ultracapacitors store electricity physically,
by separating the positive and negative charges.
• There are three types of ECs:
• Pseudocapacitors, also named redox supercapacitors,
• Electrochemical double layer capacitors (EDLCs)
• Hybrid capacitors.
• The nanomaterials typically used are metal-based nanocomposites and
conductive polymers, carbon-based nanostructures and hybrid
inorganic/organic nanocomposites, respectively.

6. Nanotechnology for sustainable energy
Energy conversion process (law of energy conversion):
• Energy can neither be created nor destroyed ; rather, it transforms from one
form to another
• Many of the sustainable energy alternatives herein described produce (e.g.
PV solar cells) or require (e.g. water splitting) electricity.
• Therefore novel more efficient ways to store electricity are very much
needed in the way to a more sustainable production, transformation and use
of energy.
• Some of the most important energy storage systems are batteries and
capacitors.
• The contribution of nanotechnology to hydrogen storage has been explored
will be in the next section devoted to the new hydrogen storage

7. Evolution of energy state for home and car applications by 21st
century (right part) in comparison with current state (left part)
Nanotechnology for sustainable energy

8. Energy conversion
Types
Direct
Solar power Fuel cells
Thermoelectric Battery
Indirect
Fossil fuel Windmill
Hydropower Nuclear reactor

9. Fossil fuel
• Formed by natural processes such as anaerobic decomposition of buried
dead organisms, containing energy originating in ancient photosynthesis.
•
• Examples are Coal, petroleum and natural gas.
• Chemical energy in the coal converted to thermal energy in the exhaust
gases of combustion.
• Thermal energy of the exhaust gases converted into thermal energy of
steam through the heat exchanger.
• Thermal energy of steam converted to mechanical energy in the turbine.
• Mechanical energy of the turbine converted to electrical energy by the
generator, which is the ultimate output

10. Fossil fuel
Fossil fuel power plant

11. Advantages to Using Fossil Fuels
• Very large amounts of electricity can be generated
in one place using coal, fairly cheaply.
• Transporting oil and gas to the power stations is
easy.
• Gas-fired power stations are very efficient.
• A fossil-fuelled power
• station can be built
• almost anywhere

12. Disadvantages of Using Fossil Fuels
• Basically, the main drawback of fossil fuels is pollution.
• Burning any fossil fuel produces carbon dioxide, which
contributes to the "greenhouse effect", warming the
Earth.
• Burning coal produces sulphur dioxide, a gas that
contributes to acid rain.
• With the United States importing 55% of its oil, oil
spills are a serious problem.
• Mining coal can be difficult and dangerous. Strip
mining destroys large areas of the landscape.

13. Fossil fuel
• Some power stations are built on the coast, so they can use sea
water to cool the steam instead.
• However, this warms the sea and can affect the environment,
although the fish seem to like it.
• Fossil fuels are NOT a renewable energy resource
• Once we've burned them all, there isn't any more, and our
consumption of fossil fuels has nearly doubled every 20 years
since 1900.
This is a particular problem for Oil, because we also use it to
make plastics and many other products.

14. Windmill
• Use of air flow through wind turbines to mechanically power generators
for electric power
• Alternate for fossil fuel
• Renewable and plenty
• Produces no greenhouse gas emissions

15. Windmill
• We've used the wind as an energy
• source for a long time.
• The Babylonians and Chinese were using wind
power to pump water for irrigating crops 4,000
years ago, and sailing boats were around long
before that Wind power was used in the Middle
Ages, in Europe, to grind corn, which is
where the term "windmill" comes from.

16. How Wind Power Works
• The Sun heats our atmosphere unevenly, so
some patches become warmer than others.
• These warm patches of air rise, other air blows
in to replace them - and we feel a wind blowing.
• We can use the energy in the wind by building a
tall tower, with a large propellor on the

17. Advantages to Wind power
• Wind is free, wind farms need no fuel.
• Produces no waste or greenhouse gases.
• The land beneath can usually still be used for farming.
• Wind farms can be tourist attractions.
• A good method of supplying energy to remote areas.

18. Disadvantages of Wind Power
• The wind is not always predictable some days have no wind.
• Suitable areas for wind farms are often near the coast, where land
is expensive.
• Some people feel that covering the landscape with these towers is
unsightly.
• Can kill birds - migrating flocks tend to like strong winds.
• Splat! Can affect television reception if you live nearby.
• Noisy.
• A wind generator makes a constant, low, "swooshing" noise day
and night.

19. Hydropower
• From the energy of falling water or fast running water.
• Conventional hydroelectric, referring to hydroelectric dams.
• Run-of-the-river hydroelectricity, which captures the kinetic energy
in rivers or streams, without a large reservoir and sometimes without
the use of dams.
• Small hydro projects are 10 megawatts or less and often have no
artificial reservoirs.
• Micro hydro projects provide a few kilowatts to a few hundred
kilowatts to isolated homes, villages, or small industries.

20. Hydropower

21. Advantages of Hydroelectricity
• Once the dam is built, the energy is virtually free.
• No waste or pollution produced.
• Much more reliable than wind, solar or wave power.
• Water can be stored above the dam ready to cope with
peaks in demand.
• Hydro-electric power stations can increase to full power
very quickly, unlike other power stations.
• Electricity can be generated constantly.

22. Disadvantages to Hydro-electricity
• The dams are very expensive to build.
• Building a large dam will flood a very large area
upstream, causing problems for animals that used to
live there.
• Finding a suitable site can be difficult - the impact on
residents and the environment may be unacceptable.
• Water quality and quantity downstream can be
affected, which can have an impact on plant life.

23. Nuclear reactor
From the Nuclear energy to electricity

24. How Nuclear reactor works
• 235U fissions by absorbing a neutron and producing 2 to 3 neutrons, which
initiate on average one more fission to make a controlled chain reaction
• Normal water is used as a moderator to slow the neutrons since slow
neutrons take longer to pass by a U nucleus and have more time to be
absorbed
• The protons in the hydrogen in the water have the same mass as the neutron
and stop them by a billiard ball effect
• The extra neutrons are taken up by protons to form deuterons
• 235U is enriched from its 0.7% in nature to about 3% to produce the
reaction, and is contained in rods in the water
• Boron control rods are inserted to absorb neutrons when it is time to shut
down the reactor
• The hot water is boiled or sent through a heat exchanger to produce steam.
The steam then powers turbines.

25. Inside the Nuclear reactor
• Steam outlet 
• Fuel Rods 
• Control Rods 

26. Nuclear reactor Problems and solutions
Three Mile Island 1979
• 50% core meltdown, stuck valve with no indicator released water,
but containment vessel held
• More sensors added, better communication to experts in
Washington, don’t turn off emergency cooling
• 28 year US safety record since accident
Chernobyl 1986
• Human stupidity turned off cooling system
• Poor steam cooling reactor design allowed unstable steam pocket
to explode
• Graphite caught fire
• Design not used in other countries

27. Advantages to Using Nuclear Power
• Nuclear power costs about the same as coal, so it's not
expensive to make.
• Does not produce smoke or carbon dioxide, so it does
not contribute to the greenhouse effect.
• Produces huge amounts of energy from small amounts
of fuel.
• Produces small amounts of waste.
• Nuclear power is reliable.

28. Disadvantages of Nuclear Power
• Although not much waste is produced, it is very, very
dangerous.
It must be sealed up and buried for many years to allow
the radioactivity to die away.

29. Solar power
• Conversion of light into electricity.
• The absorption of light, generating either electron-hole pairs
or excitons.
• The separation of charge carriers of opposite types.
• The separate extraction of those carriers to an external circuit.
• Generations :
• First : Single crystal silicon wafer
• Second : Thin films
• Third : Nanotechnology

30. Solar power
• Solar cells are converters. They take energy from the sunlight and convert that
energy into electricity.
• Most solar cells are made from silicon, which is a “semi-conductor” or a “semi-
metal”
• Solar cells are made by joining two types of semi-conducting material: P-type and
N-type.
• At the atomic level, light consists of pure energy particles, called “photons”.
• Above: The photons from
the sun penetrate and
randomly strike the
• silicon atoms. The atom
becomes ionized, passing
energy to
• the outer electron, thereby
allowing the outer electron
to break
• free from the atom. An
electric current is created.
• [www.powerlight.com]

31. Solar power
• Active Solar systems and technology:
• Active solar systems use solar collectors and additional electricity to power
pumps or fans to distribute the sun's energy.
• The heart of a solar collector is a black absorber which converts the sun's
energy into heat.
• The heat is then transferred to another location for immediate heating or for
storage for use later.
• The heat is transferred by circulating water, antifreeze or sometimes air .
• Passive solar Technology:
• A passive system does not use a mechanical device to distribute solar heat
from a collector.
• An example of a passive system for space heating is a sunspace or solar
greenhouse on the south side of the house.
• Although passive systems are simpler, they may be impractical for a
variety of reasons .

32. Active Solar power
• Harnessing incoming solar
radiation through the use of
solar collectors to produce
energy.
• Uses include water heating for
use in the home and in
swimming pools.
• As well as space heating in the
home

33. Passive Solar power
• A passive system does not use a mechanical device to distribute solar heat
from a collector.
• An example of a passive system for space heating is a sunspace or solar
greenhouse on the south side of the house.
• Although passive systems are simpler, they may be impractical for a variety
of reasons .
• Solar home design- layout
•Direct Gain- sunlight directly enters the space it is intended to heat, and is
stored and released in that area.
•Indirect gain- Trombie Walls
•Isolated Gain- sun rooms
• Heating
• Lighting

34. Advantages to solar power
• Solar energy is free - it needs no fuel and produces no
waste or pollution.
• In sunny countries, solar power can be used where there
is no easy way to get electricity to a remote place.
• Handy for low-power uses such as solar powered garden
lights and battery chargers

35. Disadvantages to Solar Power
• Doesn't work at night.
• Very expensive to build solar power stations.
Solar cells cost a great deal compared to the amount of
electricity they'll produce in their lifetime.
• Can be unreliable unless you're in a very sunny climate.

36. Thermoelectric
• Conversion of thermal energy into electrical energy
• Seebeck effect and Peltier effect
• Environmental friendly
• Lowers production cost
• Long lifetime
• No moving parts

37. Fuel cells
• A fuel cell combines hydrogen and oxygen to produce electricity.
• Fuel cells are electrochemical cells consisting of two electrodes and an electrolyte
which convert the chemical energy of chemical reaction between fuel and oxidant
directly into electrical energy.

38. Fuel cells Principle
• The core of each fuel cell consists of an electrolyte and two electrodes.
• The negative anode a fuel such as hydrogen is being oxidized, while at the
positive cathode oxygen is reduced. Ions are transported through the
electrolyte from one side to the other.
• This window of operation in its turn determines the catalysts that can be
used and the purity of the fuel to be used.
• The theoretical open circuit voltage of a hydrogen-oxygen fuel cell is 1.23
V at 298 K in practice it is around 1 V at open circuit. Under load
conditions, the cell voltage is between 0.5 and 0.8 V.

39. Schematic Representation of Fuel cells

40. Types of Fuel cells
• Proton Exchange Membrane Fuel Cells
• Phosphoric Acid Fuel Cells
• Alkaline Fuel Cells
• Solid Oxide Fuel Cells
• Molten Carbonate Fuel Cells
• Direct Methanol Fuel Cells

41. Proton Exchange Membrane Fuel Cells
• Electrolyte: water-based acidic polymer
membrane
• Also called polymer electrolyte membrane
fuel cells
• Use a platinum-based catalyst on both
electrodes
• Generally hydrogen fuelled
• Operate at relatively low temperatures (below
100°C)
• High-temperature variants use a mineral acid-
based electrolyte and can operate up to 200°C.
• Electrical output can be varied ideal for
vehicles.

42. Phosphoric Acid Fuel Cells
• Electrolyte: liquid phosphoric acid
in a bonded silicon carbide matrix.
• Use a finely dispersed platinum
catalyst on carbon.
• Operate at around 180°C.
• Electrical efficiency is relatively
low but overall efficiency can be
over 80% if the heat is used.
• Used in stationary power
generators (100 kW to 400 kW).

43. Alkaline Fuel Cells
• Electrolyte: alkaline solution such as
potassium hydroxide in water.
• Commonly use a nickel catalyst.
• Generally fuelled with pure hydrogen
and oxygen as they are very sensitive
to poisoning.
• Typical operating temperatures are
around 70°C.
• Can offer high electrical efficiencies.
• Tend to have relatively large
footprints.
• Used on NASA shuttles throughout
the space programme.

44. Solid Oxide Fuel Cells
• Electrolyte: solid ceramic such as
stabilised zirconium oxide.
• A precious metal catalyst is not
necessary.
• Can run on hydrocarbon fuels such
as methane.
• Operate at very high temperatures
around 800°C to 1,000°C.
• Best run continuously due to the
high operating temperature.
• Popular in stationary power
generation.

45. Molten Carbonate Fuel Cells
• Electrolyte: a molten carbonate salt
suspended in a porous ceramic matrix.
• A precious metal catalyst is not
necessary.
• Can run on hydrocarbon fuels such as
methane.
• Operate at around 650°C.
• Best run continuously due to the high
operating temperature.
• Most fuel cell power plants of
megawatt capacity use MCFCs as do
large combined heat and power plants.

46. Direct Methanol Fuel Cells
• Electrolyte: polymer membrane (like PEMFC).
• Use a platinum–ruthenium catalyst on the anode and a platinum catalyst on the
cathode.
• This catalyst can draw hydrogen atoms from liquid methanol, which is used as fuel
instead of hydrogen giving the cell its name.
• Operate in the range from 60°C to 130°C.
• DMFC are convenient for portable
power applications with outputs
generally less than 250 W.

47. Fuel Cell Applications

48. Advantages of Fuel cells
• Less Greenhouse Gas Emissions Fossil fuels do emit a lot of greenhouse
gases. Same is not emitted by the fuel cells.
• Reduced oil dependence it provides a best alternative to the already over-
pressurized petroleum products.
• Quiet operation fuel cells, due to their nature of operation are extremely
quiet in operation. This allows fuel cells to be used in residential or builtup
areas where the noise pollution is undesirable.
• A high power density allows fuel cells to be relatively compact source of
electric power, beneficial in application with space constraints.

49. Battery
• A battery is another common conversion device that converts electricity to
stored chemical energy.
• However, unlike a generator a battery can also store energy.
• Because they are easy to transport, batteries are one of the most commonly
used energy storage devices.
• After the energy is stored in a battery, it is converted back to electricity
when used.
•
Batteries have two terminals: one is positive and one is negative. Electrons
collect on the negative terminal of the battery. If you connect the two
terminals with a wire, the electrons will flow from the negative to the
positive terminal, as electricity.

50. Electrochemical energy storage
• Batteries are a compact method of producing a voltaic cell.
• Other methods, fuel cell, photovoltaic cell, electrochemical capacitors etc.
• Primary: Non-rechargeable
• Secondary: rechargeable
• Voltage: Potential difference
between anode and cathode.
Related to energy of reactions
• Capacity: amount of charge stored (usually given per unit mass or volume)

51. Battery Types

52. Conclusion
• Sustainable energy production, transformation and use are very much
needed to maintain the readily and cheap access to energy to the growing
and increasingly demanding world population while minimizing the impact
on the environment.
• The novel multifunctional materials produced from the broad and
multidisciplinary field that is nowadays called nanotechnology are critical to
overcome some of the technological limitations of the various alternatives to
the non-renewable energies.
• Better nanomaterials, PV solar cells are increasing their efficiency while
reducing their manufacturing and electricity production costs at an
unprecedented rate.
• Hydrogen production, storage and transformation into electricity in fuel cells
are being benefited from more efficient catalysts for water splitting, better
nanostructured materials for higher hydrogen adsorption capacity and
cheaper simpler fuel cells.