Dear students, you can visit the below web page to understand how PV-cells work
http://www.solarbotics.net/starting/200202_solar_cells/200202_solar_cell_physics.html

Solar energy:
It is otherwise known as radiant energy of sun, it is useful to us in both passive and active form.
Passive form:warms up earths atmosphere.
People in temperate regions are spending more money for room heating, because availability of radiant energy is not as much intensive as in tropics.Hence by designing their houses in a manner that suns rays are better trapped through wall made of glass (special type) and facing north.All the heated up air is circulated to rest of the rooms using exhaust fans. The Above technique conserve lots of money which otherwise spent for room heating.
Active form solar energy:
Solar energy can be collected, concentrated with the help of some devises. They are:
1. Collectors
2. Concentrators
3. Photovoltaic cell(s)

Collectors are used to collect the radiant energy of the sun and convert it into thermal energy and store the energy in energy storage system (water).
Example:
Solar water heaters
Solar cookers
Concentrators:
These are the devices, used for concentrating the radiant energy of the Sun at one point with the help of parabolic mirrors or concave lenses.They will have a sun tracking mechanism.Hence their energy out put does not get easily affected.
Photovoltaic system:
These devises are used for converting solar radiant energy to electrical energy using semiconductors.Semiconductors are materials which act both as conductor as well as insulators.Silica is normally used as semi conductor in PV-cell, since their availability is enormous in our Earth.It behaves as a semiconductor, if it is added with some impurities(other minerals rich/ poor in electrons).Such process is called doping.
Components of PVC:
N-type conductor:

1. -posses a negative charge (Rich in electrons)
2. -always kept as top layer
3. -also known as absorbing layer/absorber
   

Electron barrier:

1. Allows only the electrons of higher energy level

P type conductor:

1. -posses a positive charge
2. -number of electrons are less (called normally as holes)
3. -it is kept at the bottom of the membrane barrier(ion selective membrane)
   

Working mechanism:

When the absorber layer is exposed to the suns radiant energy, electrons absorbs photons and become excited and jump through membrane towards electron deficit p-type conductor and occupy the holes in it.after most of the holes are filled up the charge become negative and because of electron lose the n-type now quires positive charge and since both the conductors are connected through proper circuit, these fast moving electrons are channelized and go on moving from n-type to p-type and vise verse.Electricity is developed because of electron movement and voltage difference between the two conductors.The nature of electricity generated by the above process is DC.It can be stored in batteries or directly used and if needed, can be converted to A/C by using an inverter.

Energy

Module 1
Energy: Introduction,forms of energy, Types/ classification of energy resources-origin, availability, cost of production and technology. Fuel poverty . Growing need/energy crisis. Energy scenario in India.World scenario of commercial energy.Energy policy.

Energy:
We can say that it is an inherent ability of a substance to change.Here an important thing that u require to understand is the word ‘change’;which means any modifications, it may of minute in nature or large.
In school days we have been told that energy is the capacity of any system to do work.though it seems right, among learners who are new to thermodynamics, the word work would mislead them.
SI unit of energy is Jule,denoted by the letter J.(It is the amount of energy quire to raise the temperature of 1 gm of water to 1 °F)
Forms of Energy:
There are seven forms in which energy is exist, they are:
1. Light/Radiant Energy-vertical movement
2. Heat/Thermal Energy-due to induction/friction/vibration
3. Chemical Energy-stored between bonds
4. Nuclear/Atomic Energy-stored within nuclei of an atom
5. Mechanical energy-arrived through machine
6. Electrical Energy-movement of electrons
7. Sound energy-horizontal movement
Properties of Energy:

Always move from high to low level (example: if you keep a hot tea cup in a basinful of cool water, you can notice some change in temperature both in the basin as well as in tea cup; tea cup will loose its excess heat due to its close contact with the surrounding water. as a result, water will gain heat from the tea cup.The above process will take place continuously until the temperature of both the things attain equilibrium.

(It strictly obeys the law of thermodynamics)
Energy, neither be created nor destroyed (Law of conservation/the first law)

Energy can change its form from one to another. During the change, some amount of it is wasted.(Entropy)
Energy resource classification:
Strategy:
1. Availability of a resource:
a. Perpetual(solar)
b. Renewable(wind,water,geothermal,OTEC*,Tidal,Biomass)
c. Non-renewable(Coal, petrol,Natural gas,Radioactive minerals)
2. Cost of generation, distribution
a. Commercial-coal,petrol,natural gas,Nuclear)
b. Noncommercial-(Hydro power,Biogas,solar power)
3. Nature of Technology used
a. Conventional –(coal,petrol,natural gas)
b. Non conventional-(solar, wind,OTEC)
4. State of existence
a. Kinetic-exist when object is in moving state
b. Potential-exist when object in rest(stored form of Energy)
NB;if it is closed loop, it comes under renewable otherwise non renewable.

To days assignment:
Difference between perpetual and renewable energy resources
What energy a compressed spring possesses? When it it is released back, to what form it is converted?

Lecture 2 Bioremediation

Bacteria:
Cell structure
The size of Bacteria are ranged between 0.5 and 1.0 micron.cell wall is made up of peptido glycon(procaryotes).In gram negative bacteria a lipid layer is found over that.Which consists phospholipids,protein and lipo poly saccharides (LPS).

The Lps is also known as Endotoxins the outer membrane has some channels of protein called Porins which allows secretion of extracellular enzymes such as proteases, pectinases ans amylases.it also facilitate signal transduction.Beneath the cell wall is the cytoplasmic membrane and is composed primarily of protein and phospholipids.It act as a selective barrier for the penetration of water soluble molecules which allows entry and exit of nutrients and waste products. More importantly ATP is synthesized here. The enzymes present in the cytoplasmic membrane are involved in respiration and synthesis of cellular materials. Damage of membrane will cause death to an organism.
Eg. Bacillus, Pseudomonas
Viruses:
Acellular Microbes are called viruses.They are obligate,intracellular inhabitants means always need host for their replication.They do not possess any cytoplasm orcytoplasmic organells
Eg.TMV,PYV,Dengue virus

Bacterio phages:
Widely distributed in nature.Seen in water, soil, air,plants and animals which infect bacteria.It contains a head, neck, collar and tail with six spikes.These are extremely useful in bacteria identification and classification
Microbial metabolism:
Cell functions or undergo changes only due to metabolism or through chemical reactions.It includes all type of chemical reactions that take place within an organism
Anabolism:process by which chemicals coming from outside is utilized by the organism for their own biomass buildup after converting them into utilizable form .Which is otherwise known as biosynthesis
Catabolism: complex substances are broken down to simpler substances for their further utilization for energy generation.
Assignment:
What are Biomolecules: Carbohydrates, proteins and Lipids

Bioremediation

Lecture1.

Abstract of today's Lesson:

Concept introduction:

Bio means living things and remediate is bringing something back to its original state. Hence the word bioremediation express the usage of living things for the removal of pollutants from the contaminated sites.

Unique feature of bioremediation:

In chemical and physical method we use powerful chemicals and energy resources to execute the clean up process. Though such processes are rapid, production of toxic end products is inevitable.Management of such secondary wastes become a burden for the firms.whereas this nature friendly technique, differ from the rest of the waste treatment techniques in following aspects;

1. Nature friendly.
2. Suitable mostly for organic contaminants
3. No toxic intermediaries produced most of the time.
4. Pollutants are completely are partly converted into innocuous forms.
5. Gives permanent remedy

Types:

1. Microbial remediation
2. Phyto remediation
3. Zoo remediation
4. Myco remediation
5. Phyco remediations are various types which are mainly classified based on the type of living agents put under usage.
   Home assignment:
   Dear students before coming for the next class, do familiarize yourselves with the following terminologies:
   Difference between :
   
   • organic and inorganic substances
   • aerobic and anaerobic respiration
   • Micro organisms
   • adsorption,absorption and immobilization
   • how energy is produced from food we eat
     NB:I have asked the class to put a separate file for continuous internal assessment.absentees are asked to contact year rep for further information.
     syllabus for the course is given to the class rep, kindly get it xeroxed.