SOLAR ENERGY-1

[Music] [Music] [Applause] [Music] [Applause] [Music] hi friends now we will discuss on the second part of the course that is renewable energy production in the first part we have covered how the fossil fuels can be processed to produce clean energy and in this part we will discuss on the renewable energy production and in the introduction class we have discussed that different types of renewable energy resources are solar energy hydro hydro energy and biomass energy wave and tides geothermal energy etcetera so we will discuss on this topic in this part along with energy conservation and now we will discuss on solar energy and the contents our Sun as a source of energy then solar radiation and spectrum then solar insulation then application of solar energy advantage and disadvantage of solar energy then techniques for solar energy production or conversion to usable form that is solar thermal and solar photovoltaic so in the first part we will be discussing up to advantage and disadvantage and the second next class we will discuss this part so as you know that Sun is the source of all type of energy in the ecosystem and we cannot consider any life without the energy and if we see the components of ecosystem obviously the multi component our most important one and then a biotic components which are required for the survival of that and another is your sunlight that is the energy so this energy is very very important component for the ecosystem and this energy comes from the sunlight as you know the solar radiation that is accepted by the plants the plants use it for the conversion of organic compound through photosynthesis and that is the source of energy to the others that is the producers then consumers so if we see the primary secondary and tertiary consumers all living organisms are dependent on this energy stored in a food produced by the primary producers now we will see how much energy it's coming from solar system to the art and how much is being consumed by different living organisms and what is the scope for the utilization of solar energy to convert it into some other usable forms so here this figure shows us that incoming solar radiation is around say four point nine eight into ten to the power six you need if this is the total radiation then out of it non utilized is four point nine 7 into 10 to the power 6 unit so only 0.2% solar energy is used by the water trough for the production of organic compound and it is around say four six six zero you need so out of this 466 zero unit which is taken up by the producers or the plants and grasses etcetera so they say in around six thirty units to Harvey Burris and rest is lost either respiration new compositions and not utilized that is the sediment so this is the distribution of the total 4660 units of energy and sixty T is coming six thirty it's coming to Harvey for us then out of six thirty one twenty five is going to carnivorous so these are the distribution of solar energy which is coming to the art and taken up by the plants through its photosynthesis for organic carbon organic compound productions and the forward flow so it is very clear that most of the solar energy is remained used and if we can develop technology to harness this one to convert the solar energy to usable form then it can be a good option and that can be renewable energy for our use then you see what is the source of this solar energy we know that there are different types of fusion reactions are going on in the sod in in the Sun and the energy is released due to these fusion reactions so here say deuterium tritium they are fusing and producing helium and then Neutron and energy is released so this energy huge amount of energy produced in the Sun it's taking some time to come at the surface of the Sun and then when I said it may takes thousands of years and then when it is coming to surface of the Sun then it is radiated and it is coming towards the art and if we see from the Sun the energy is coming to the art so out of the total radiations which is coming towards the art around 46% is absorbed by the art and 6% is deflected by the earth's surface so remaining part of the energy is not able to come to the Earth's surface because of clouds and ionosphere etcetera so we see her energy dispersed in the atmosphere is around say this 8% and energy absorbed by the vapors and low zone and dust is around 19% and for cloud we see her four percent energy is absorbed by clouds and 17 percent is reflected by the cloud so this is the total energy distributions from the Sun which is coming to the different sources to the different parts and ultimately we are getting 46 percent of energy absorbed by the earth now this energy comes to the art in terms of radiations and with a very high speed and that say it takes eight minutes to reach outer atmosphere of the art that is 93 million miles away from the Sun so this is the this is the way the radiation reaches to the Earth's surface now if I want to use this energy if we are interested to use these energy we have to know more about the characteristics of these and then we have to think how they technology can be developed so we will see now now what is the maximum available solar energy per unit area per unit time on that way solar constant has been defined and that solar constant is the maximum intensity of solar radiation which is defined as the total energy received from the Sun per unit time one a surface of unit area kept perpendicular to the radiation in space just outside the Earth's atmosphere so in the art atmosphere it's end at that time if we place a surface which is perpendicular to the radiation so per unit area per unit time how much radiation is coming that is called the solar constant and this value is 1 3 6 6 watt per meter square and this figure shows us that UV visible and infrared all are available in the solar radiations and and we see spectral irradiance is highest in case of visible light so this is within say 400 to 700 nanometer of wavelength now we will see the different wavelength of solar radiations we have that is visible light here to here other way we have say gamma ray x-ray we have infrared so more the wavelength as you know the energy is less and so that is why this part is having high energy this part is having less energy so these are the different types of rays which are available in the inner solar radiations coming to the art so we have to trap these the energy associated with this radiation and convert it into usable form so that is the basic concept of the energy conversion from solar to electricity now we will see the solar insolation so we have discussed about the solar constant that is the maximum possible energy intensity which is coming to the ark at the atmosphere of Earth's end and now at any location on the Earth's surface the radiation is also coming and in that radiation intensity will be defining a solar insolation so the solar radiation received on a flat horizontal surface at a particular location on earth at a particular instant of time is called the solar insolation and usually expressed as what per meter square so that solar constant was also what per meter square then insulation is also watt per meter square now there are many factors which influence the solar insolation what are those angle of incidence daily variation then seasonal variations and geographical location of the particular surface then atmospheric clarity then shadows of trees tall structures adjacent solar panels and then degree of latitude for the location and area of surface what is the surface we are considering for the collecting of the solar radiations that will also influence and then solar insulation is not available equally everywhere in the world because all those factors are not equal it is variable that is why the solar insolation is also different from place to place now we will see what are those factors so we have seen that angle of incidence is the important factor for the insulation so what that angle of incidence each say if we have one flat plate then that plate is fixed on a particular area then sun rays are incident on it so that incident beam and the normal to the plate will make some angle here the theta that is called your angle of incidence so the angle between the incident beam and normal to the surface is this is this this theta is your angle of incidence now so if it is our ibn this is the intensity of light here so in this case normal to this will be getting I n so I n is equal to IV n into cos theta I be n into cos theta so this is the relationship between this iron and I BL now the angle of incidence this will also depend upon many factors like say angle of declination angle of tilt and then our angle latitude associated with a place so these are the different factors which influence the angle of incidence now the fixed type of collector surface s should be so worried indeed that it collects maximum energy from the Sun so that is the main objective that maximum energy will be collected on the collector then say what is the tilt angle so if we keep one plate then from the horizontal side horizontal line it will make an angle so this is a horizontal plane then this surface is making angle so this is called beta or tilt angle so this this tilt angle will be zero when the surface is horizontal at that place or it will be 90 degree and the surface is 90-degree vertical to the surface so beta is always positive and this beta for a fixed collector it is fixed but for Sun tracking collectors this beta value can change with time to track the Sun to get the maximum radiation from it now our angle is also one important term which is related to the energy production or the capturing of the radiation from the Sun by the collector so here we see these our angle is defined as the angle traced by Sun in one hour with reference to 12 noon so at 12 o'clock and noon the W is equal to zero then what will be the the value of our angle we can calculate by using this formula w is equal to 15 into st minus 12 that is st is the is the local solar time so so at at 9:00 a.m.

If we want to find out the W value so W at 9:00 a.m. will be 15 into St that is 9 minus 12 so minus 45 degree so this side we are getting minus 45 degree here we are getting now at 6:00 p.m. that will be 15 into 6 plus 12 18 minus 12 so 90 degree so we'll be getting 90 degree at 6:00 p.m. so here we're having this angle so this is our hour angle so our angle will also will also influence the intensity of intensity of solar radiations on a on a plate or collector and then angle of declination that is another parameter which is defined as the angle between the line connecting the center of Earth and Sun with the equator plane so equator plane we have here and this is our Sun and art so this angle is our angle of declination so angle of declination will vary from time to time seasonally throughout the year this value will change if we as we know that the maximum value is plus twenty three point four five degree on 21st June and minimum is minus twenty three point four three four five degree on December 21 and on equator I mean the angle del that is the decline Asian angle is at two equinoxes that is mass 21 and September 21 the del value 0 so what we will see this is 21st December and here it is we are getting 21st June so this is 2 and this is our 0 so these are zero value two equinoxes we are getting here so we can calculate what will be the del value on any time by this formula del is equal to twenty three point four five sine 360 by 365 into 284 plus n where n is the day of of the year counted from the first January say first generally second generally like this how many days from the first January that is if we put here then we will get the value of dill and this value will also influence the solar radiation on the incident on a particular area of a collector and then latitude will also influence the insulation value so here what is this as you know that this is the angle between the the radial line joining the center of the art and and the point where the where the collector is situated with the equatorial plane so this is our equatorial plane and this is our point where we have put a we have put a plate collector say say this is our collector this is our point on the Earth's surface so this point and this is connected by this radius Earth's radius and this is our equatorial plane so this angle is called latitude so latitude will influence the solar insolation on the surface of this collector along with this beta also this is our horizontal into the surface and this is also the beta is our tilt angle so tilt angle and latitude both will influence the the insulation value at this point or at any point so these are the factors which influence the availability of installations on on Sun now what we will do with this solar energy initially that the solar technology for the conversion of this energy of the radiation to the electricity was not matured and and at that time also the solar energy was used and important applications of this energy are water heating and then they are heating for agriculture and industrial applications like say drying up any any feed crow in any crafts or any feedstock for processing or even say wish'd sludge slash drying everything are some example these are some example of the application of solar energy directly in industry and in agriculture and then heating and cooling of buildings to heat and cool building that solar energy can also be used so we have to design the buildings in such a way that we can capture energy when needed from the Sun and we can avoid energy from Sun when needed so that it's passive design of buildings we will discuss that and then cold storage for preservation of food that is also an application of solar energy people have used it cooking of food and then greenhouses just I have told that or you know we have to building the we have to design the building in such a way that it will be consuming less amount of energy and these to be distillation of water and water pumping solar furnaces and then power generation and solar photovoltaic these are the two latest development on the solar technology that is for power generation and then solar photovoltaic we will discuss those part in the next class and now we see the heating and cooling of buildings how this can be done so if we see that during summer the Sun will be literally at more elevation and then it will be coming to the top part of the roof and if if it is extended some part is extended at the roof so that summer Sun can be can be arrested it will not be allowed to come into the into the house to some extent we can manage but in winter here the Sun can come sunlight can come through the windows so these windows which is the light which is coming in in the house then we can store it we can make some stone floor so that will be capturing the heat which is coming to the solar radiation inside the room and then you can put some insulation so more higher the insulation will be able to keep the heat in the room for a longer period so one is your we have two collection then another is your storage by using this material so you can store the heat and then reduction by insulation these are the principles to design the buildings that is called passive building design so passive solar design that is nothing but a set of practices that occur that accommodate the local climate by letting the Sun into the house into the building in the winter and keeping the Sun out in the summer so this is the principle it is designed in such a way some example is here homes in Montana and California with a passive solar design hits the house in the winter and cools the home in the summer and here we see here this is our summer Sun at higher elevation so it is coming here and that winter Sun at lower elevations the Sun is coming to inside the room see if we have that we are talking about that absorbers we have to use some materials which can absorb heat and we will also use some thermal mass though thermal mass can capture more heat than them so we have we can select some thermal mass which can which can store the heat and apply to the room and we should have some ventilation arrangement also so these are the these are the these are the technique or processes or the practices we can say through which we can make the make the building a green building and reduce the energy requirement for the building and this can be done basically by using windows in the South face so efficient heating starts with proper collection of solar energy that can be achieved by keeping south-facing windows and appropriate landscaping and then that is the collection part and storage we can do that using thermal mass some examples are here what are our on would break concrete loose stone the different amount of energy they can store per cubic feet per degree Fahrenheit so that is it is given some data are given and insulation that also to to reduce the loss from the room and on external walls roofs and the floors we can do some insulating materials so that the building can be of of green building in nature and by this design it has been reported that it passively heated homes uses about 60 to 75 percent of solar energy that heat is all sand windows and the Center for renewable resources USA estimates that in almost any climate a well-designed passive solar home can reduce energy bills by 75 percent with an added construction cost of about five to ten percent about twenty percent of energy used for water and space heating and the major factor for which the solar energy is not being used widely is its cost previously it was very costly but now the cost has reduced and application of solar energy is becoming a reality and people are getting more interest day by day to use solar energy in different F Asians no advantage and disadvantages of this solar energy if we think they know me asleep now whatever the reaction is taking place for the production of this energy solar energy that is taken place in Sun so art is not getting any pollutants from this so all polluting byproducts that through chemical radioactive and thermonuclear sources those are inside the art only pure form of energy reaching to the art that is one major advantage of this solar energy that it is pollution free and the energy reaching the art is incredible the huge amount of energy a calculation says that 30 days of sunshine striking the art have the energy equivalent of the total of all the planets fossil fuels both used and unused so these are the advantages of this process it can be very good to renewable source it will never end and it also has some disadvantages because sunshine is not a continuous process it is not continuously that is not consistent there is a cloud there may be rainy season or at the night time will not get sunshine so what we have to do solar energy is a diffused source so to harness it we must concentrate it into an amount and from that we can use such as heat and electricity etc so we have to store the we have to convert the solar energy into some form of electricity then you have to store it then only this technology will be very very interesting and great successful so after this in this class thank you very much for your patience [Music] [Applause] [Music] [Applause] [Music] [Music]

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