 Hello everyone welcome back. So, we are going to continue from the previous session in the previous session again this is the outline before you we looked at the units and the terms then the conventional energy resources that we use today and then the depletion and the risks that are associated with that. Now we are going to change gears and we are going into looking at environmentally benign, benign means not harmful. So, the environmentally friendly forms of energy so to speak and then we look at some of the efficiency measures that we need to take in our existing ways of using energy and then towards the end I have a list of some things that people in different fields can do in order to help alleviate this issue and there are like what chemical engineers can do, what materials engineers can do and so on and so forth as well as what a regular consumer can do. So, now let us continue with the environmentally benign forms of energy. Somebody had asked about solar energy and I am definitely going to talk about that. So, if you look at the alternative energy forms the environmentally friendly forms there is good news the continuous or renewable energy sources they are they far exceed human needs at present at present whatever is the human energy consumption compared to that there is far more available. So, and in general we also have technology to harness it in general, but there are some gaps. So, that is where there is tremendous scope for R and D as well as commercialization efforts. So, there is there are huge potential markets in this area. Let us start off by looking at the global energy flows mainly everything is driven by solar energy the entire biosphere on the earth is powered by solar energy. So, you have large quantities of solar energy coming in into the atmosphere some of it is intercepted by the atmosphere part of it is reflected some of it is absorbed by the atmosphere some of it reaches down and is absorbed by the earth part of it gets reflected from the earth surface. So, the fraction that gets reflected from the earth surface as observed from space is called as the earth's albedo albedo that is the whiteness or the reflectivity of the earth. Some of the light as I said gets reflected then the part that gets absorbed by the earth surface leads to heating of the earth. So, when any black body you must have studied in physics when any object gets heated up it will start emitting some radiation depending on its temperature. So, it gets heated up and it starts radiating energy and so, there is some radiation that goes out from the earth and part of that radiation because the earth's temperature is average temperature of the globe is very low the emission is in the infrared. So, that long wave infrared radiation part of it is absorbed by the earth atmosphere due to gas molecules which we know as greenhouse gases. So, the most dominant among them is water vapor followed by carbon dioxide. This is kind of surprising and shocking to many people carbon dioxide is not the most important greenhouse gas it is water vapor which is the most important greenhouse gas, but water vapor the level of water vapor is regulated by the water cycle and the temperature. So, the anthropogenic contribution is not in terms of increasing water vapor the anthropogenic contribution to global warming is due to increasing of the other greenhouse gases such as carbon dioxide and methane. So, anyway so, this greenhouse gas molecules they absorb the emission part of the emission of the earth and as the infrared radiation couples to the molecular vibrations of the those gases and they as they vibrate they they reemit the same frequency part of it goes into outer space, but part of it is shot back to the earth which leads to a slight additional heating of the earth and that is what is global warming. Whatever the reason I am showing you this is because this will help you understand the global warming problem it will help you connect many things and it will also help you to understand that the entire biosphere is actually powered by the sun. So, it is the energy from the sun that is the basis of the entire biosphere even wind energy for that matter is solar energy indirectly because it is solar radiation that heats up the atmosphere leads to the thermal currents which is what is wind and of course, there is contribution from the rotation of the earth also, but the main driver is solar energy. So, if we look at the global energy potential of various forms we see that solar energy is huge this is the world energy consumption see how small it is and see how large this is and then we have the fossil fuels you have coal, coal is also pretty large the amount of coal that is present is is quite large this is the annual consumption and then you have uranium you have oil natural gas all these fossil fuels are basically solar energy that was converted into chemical energy many many years ago. So, this also is indirectly solar energy, but except that it happens over a much larger time frame and again you have wind over here biomass hydro and so the potentials of these are are relatively small, but solar energy is plentiful. So, another graphic which kind of emphasizes how plentiful solar energy is. So, over here what you can see the various colors that you can see are indicative of how much solar energy falls on that region. So, the redder it is the more solar energy you have and the bluer it is or green or blue you have less and less solar energy. So, on this world map you see these black spots on each of the continents those black spots are something like 100 kilometers or something whatever they are in dimension it is if those areas are covered with solar panels operating at a very low efficiency of 8 percent commercial photovoltaics panels systems operate upwards from 14 percent polycrystalline silicon. But let us assume that the solar panels we have over here are operating at a very low efficiency of 8 percent then these black spots will capture enough energy to serve the world's energy needs. Now this data again may be a little out of date, but it again it communicates the message that there is plenty of solar energy. Now this is only this diagram only indicates how much solar energy is available it does not specifically address the issues that exist with solar energy and we are going to talk about those issues right away. Just for curiosity sake I have shown this solar spectrum the light that comes from the sun it comes in various wavelengths or packets of energy and the orange curve over here is the solar spectrum as it is outside of our atmosphere as it enters the atmosphere some of it gets absorbed some of it gets reflected and so on and so forth. So, you see the what is known as the extraterrestrial spectrum which is the spectrum seen outside of the earth's atmosphere is this whereas the inner curve corresponds to the terrestrial spectrum maybe at sea level. So, you see that there is some drop in the flux that reaches here that is due to the absorption process and you see that at certain wavelengths there is almost total absorption. So, this is due to the various greenhouse gas molecule. So, you have over here you have absorption due to oxygen ozone the photochemical reactions that lead to the formation and degradation of ozone in the atmosphere on this side you have absorption by water vapor carbon dioxide and the other greenhouse gases ok. So, solar energy is actually wonderful and versatile there are two distinct types of applications of solar energy one is the heating kind of applications heating cooling kind of applications and then the second is electricity generation electricity generation can be made through heat. So, by heating you can generate steam and through the steam you can run turbines to generate electricity. So, that is one way and the other way is photovoltaics. So, all these technologies have been implemented and there are practical examples of each of them and I am going to show you some very interesting. I think we are familiar with some of the usual examples, but I will give you some which are not so common which many of you might not have seen or even thought of. So, they were surprising to me. So, I assumed that many people would enjoy watching those ok. If we just take a look at PV. So, what is PV? PV means photovoltaics photovoltaics means harnessing of solar energy they usually have a semiconductor material and it directly gives you electric current. So, it is the solar cell technology. Solar cells are photovoltaic there is the other one which I mentioned is called as solar thermal where you heat up a fluid and you rotate turbines in a thermodynamic cycle and then you generate electricity that is the other kind. So, if you look at just the PV market you see that it is rising very steeply from year 2000 to 2013 you see how steeply it is rising and in various parts of the world. This technology is very promising and it has it is going to go a long way now I think it has hit the imagination of the common man and I think there is only growth that I can see further. So, this technology may look good, but there are definitely some issues one of the major issues is intermittent. What do you understand by intermittent? Intermission we are all familiar with the word intermission in a movie. So, intermission is a break. So, solar energy is not available continuously it is available in breaks. Now, the good thing is that solar energy can be very solar radiation can be very easily predicted. In fact, in another course that I teach all the students actually make very good calculations of what the direct solar intensity is going to be at so and so time of the year and so and so time of the day. So, it those calculations are very easy, but the only unpredictable thing that comes is due to cloud cover. So, cloud cover can bring in lot of unpredictability because the weather models are not that sophisticated that it is going to exactly predict when in a particular region there is going to be cloud cover and when it is not maybe general predictions are more accurate as compared to like very specific predictions. There was another point over here is that in many places large amounts of energy is required during the day time particularly in industrial regions large amounts of energy are required during day time. So, solar energy is also available during the day time. So, in this changes from city to city or place to place, but in certain places when the demand is high during the day under such circumstances solar energy can become a very good form of energy because it is also available during the day otherwise you have a storage problem. So, in places where the evening time normally lights and in urban places everybody turns on the lights and all your televisions and gadgets and things like that. So, at that time there is no sunlight. So, then there is a mismatch. So, how to meet that demand becomes a problem and that can only be met with the known conventional energy forms. Nevertheless as long as the sun shines if it is connected to the if the solar installations are connected to the grid then they can at least take part of the burden. So, that some conventional fuels can be saved. So, connecting to the grid connecting renewable energy forms or these continuous energy forms to the grid is a great idea and it should be done, but there are some practical problems that grid infrastructure that we have today and in many places it is not very reliable. So, it cannot take on too many of these renewables because of their intermittence they are not very predictable. So, it becomes a it is a real nightmare to ensure that the demand is met through unpredictable sources. So, a significant amount of conventional energy forms need to be still connected to the grid until we develop some alternatives and which I will also discuss. So, how does the grid connected system work? Let us say that you have solar panels on your rooftop and the electricity company or the electricity grid they allow what is known as net metering or bi-directional metering. So, there is a meter which will run both ways it can run forward or it can run backward or there may be two meters and one measures how much energy you are taking from the grid and the other measures how much energy you are supplying to the grid. So, each consumer can be a potential supplier. Now, the green curve or the green area is the energy that you require. So, this starts at 12 midnight and goes to 12 midnight the next day. So, this is the time axis and over here is the kilowatts of power used. So, at midnight obviously your use is very less and then in the morning it kind of builds up and it peaks sometime around evening in your home when you turn on all the lights and everything and then towards night it goes on decreasing. So, this is the load curve and if you have solar panels on your roof then it they would be generating in a in this certain time span whenever the sun rises the production would gradually increase and be maximum around midday and then go on decreasing. So, while you are connected to the grid you are supplying to the grid. So, the energy bill that comes to you would not be equivalent to the entire green area, but it is it is the green curve minus the gray curve. So, you would be paying only for that much and if you if you oversize your panels in other words you have instead of putting a 1 kilowatt panel if you put a 3-4 kilowatt panel then this curve would be this big and you would even end up getting a check at the end of the month instead of a bill. So, that is that is the whole concept. So, in concept it is a great idea except you can see the problem right away that you need to depend on the grid the solar installation is not going to give you power all 24 hours. There is another issue with solar cells are quite expensive, but there has been a steady decline and I am afraid I do not have data on that, but the cost of solar cells is reducing very rapidly I think due in part to China, but the costs have decreased very significantly and they are now very cheap and there are other technologies of solar cells apart from the polycrystalline silicon or the single crystal silicon which are which are even cheaper for example, disensitized solar cells these are very cheap they are they also appear they have even been applied on flexible substrates. So, you can essentially have a flexible substrate which can work as a solar cell. So, cost is coming down and I think it is only a matter of time before it becomes very very affordable. There is while many developments are happening in various parts and in various areas one interesting development is building integrated photovoltaics. So, the concept is something like this you have to pay for building material you need a roof over your head and the roof is made out of some material and it has some cost. So, if the solar cell can work as a roof tile even if the solar roof tile is a little bit more expensive than the regular roof tile you are you are not duplicating things. So, in that sense there is some cost saving also if these panels are integrated then they look very nice it looks very beautiful these entire facades that you see over here. So, this is another concept that is coming particularly in in these green buildings. Another thing if your roof in general it is exposed to the sun whether you like it or not and it is gaining heat. So, the building your house becomes so unbearably hot in summer because the walls and the roof is exposed to sunlight and that sunlight whatever of it gets absorbed is only heating the home and that heat you have to somehow you drive out in order for the home to be livable therefore, you have to install an air conditioner. But if part of it is absorbed by is converted to solar energy then you have some little bit of respite from the heat. So, you can reduce building heat gain by putting such structures. So, it could include solar water heaters or it could be solar PV panels. I am going to now show you another concept there is a maybe non-engineers are not familiar with this there is something called as cogeneration. So, cogeneration is generation of electricity as well as heat. If you remember from maybe high school or first year of engineering you have these your steam rank in cycle or your power plants normally operate at relatively low efficiencies which are they are low because of some laws in thermodynamics. We must have studied the Carnot cycle efficiency which depends on the two temperatures. So, there is a thermodynamic limit to how much how efficient heat engine can get and that cannot be easily violated. As a result if you have any even if it is a fossil fuel based generation the entire heat of the fuel never gets converted into electricity only part of it gets gets converted. So, let us assume that if no special design is made let us assume that that efficiency is roughly 30 percent. So, only 30 percent of the fuels energy is converted to electricity whereas, 70 percent gets wasted. So, the waste heat goes through the chimney and really that is that is not of any benefit to anyone. Now, cogeneration will actually capture that heat and use it for some other purpose. So, if you take the electrical generation as well as the heat output if you club the two then overall you will be utilizing a greater fraction of the of the fuels energy without violating second law of thermodynamics. So, that is that is the whole idea of cogeneration. Now, that cogeneration can be further extended into multi generation. So, multi generation means you are not only generating electricity and heat electricity plus heat generation of two forms of energy is called as cogeneration, but you can even generate cooling. Now, how do you generate cooling out of heat? It is a it is a very old technology people at least some people probably have heard of absorption chillers. I think the technology must be more than 100 years old that is how they used to make ice before our vapor compression cycles. So, the absorption chiller works on it takes heat from at one end and it provides cooling at the other end. So, there is a thermodynamic cycle that enables that to happen. Cogeneration or multi generation is some something that can be applied to even fossil fuels and it should be applied there are many places where it has already been done towards the end I have a couple of slides on that. This video is about solar cogeneration. So, you have solar thermal energy and that thermal energy is going to be converted partly into electricity and partly into heat. There are two approaches to do that one is one is you can have high temperature photovoltaic. So, you concentrate using a reflector you concentrate solar light on a very small sized solar cell which operates at a very high temperature and on the back side of that solar cell you have a heat exchanger. So, it heats up a fluid and that heat can be used for some other purpose and the small solar cell is generating electricity. So, this is one approach the other approach is you simply make steam and you operate maybe a steam rank in cycle or you may be an organic rank in cycle and then you have for the waste heat you have another another way to take care of that through heat exchanger or a bottoming cycle whichever. So, there are couple of ways in which it is done and there are in fact I am pleasantly surprised that there are even companies which are started based on these ideas. There is another issue related to solar energy and that is that it is very diffuse. Diffuseness means low energy density. So, per unit area there is little solar energy available. It is not like you can have a small size solar panel and it is going to power your entire home. If you want to power your entire home you would need a very large size of solar panel. So, how do you how do you address this diffuse diffuseness problem? You can concentrate the solar energy and then it can you can in a small area you get greater energy density. So, that is one of the ways and these parabolic reflectors or there are lenses, Fresnel lenses can focus the light on a relatively small area. This is this has been used for even industrial steam production. So, in the multi generation that I said you can make steam for industrial processes also not only supply heat for domestic purposes. Some of the very large solar thermal plants look somewhat like this. So, what you have over here is a is a whole huge farm of the solar reflectors which are all they are they have microcontrollers and they are tracking the sun. So, as the sun moves through the sky these panels also follow it. So, they are tracking the sun and they are reflecting the light all to this central tower. So, this is called a heliostat. These reflectors are all focusing their light on to the central tower and that tower gets extremely hot this this point gets extremely hot and then there is a there is a heat exchange fluid sometimes it is a molten metal or molten salt or something like that which is the fluid and that carries the heat to these stored tanks over here which contain that molten salt. So, you have a lot of energy that is stored in the form of heat in the molten salt. Now, this is a this is something really beautiful which is not available with photovoltaics is that there is stored energy. So, you have energy that is stored at a very high temperature being at a high temperature you can efficiently use it you can efficiently convert it into electricity the higher the temperature the more the efficiency in conversion. So, it is high grade heat that you are storing over here and you can essentially run this plant 24 hours. So, even when the sun goes down you still have accumulated adequate amount of heat to run it for the night until the sun comes back up in the morning. But this such a such a system would work better if it is in a in a dry dry region like a desert or somewhere where it does not get too cloudy because if you have several cloudy days in a line then you would have problems. I am going to show an animation about that stored solar thermal also. Now, similarly just as you have solar energy which is at least in the PV market is rising very fast. Similarly, generation of electricity from wind also has been rising very steeply and the prices are also very good. There are many issues related to wind energy the its integration with the grid its unpredictability and the even even the government electricity boards not being able to pay up to the wind producers. So, there are many issues but I think we need to systematically solve all those issues. Now, yes there is geothermal energy there is tidal energy but I showed you that resource map the availability of resources it is relatively small and again it is localized in some places. Wave energy is is not a mainstream yet solar and wind are are really in many places they have achieved grid parity meaning the cost is cost is comparable to the grid prices in many places under many conditions. So, that is why I am paying a little more attention to them as if the other technologies mature up then we would be discussing that also. Wave energy again there are issues that diffuseness is a common issue with all of them. So, if we just have to summarize what are the main barriers for these renewable and continuous energy forms then they would be intermittence it is an issue that is common with wind solar wave tidal not with geothermal. Geothermal does not have that problem there is another issue of unpredictability or poor predictability. So, with solar energy there is good predictability except for weather conditions. So, if there is cloud cover then that is a problem otherwise solar energy is highly predictable with wind energy again the predictability for integrating on a large scale with the grid they would ideally want to have an hourly prediction for those regions and in many places at least in India that data is not available or it is not so reliable. This diffuseness or low energy density is a problem, but there are ways of overcoming that and in spite of the diffuseness and all that the efficiencies that we are getting are pretty good. Now, just to put things in perspective we know that the biosphere is so diverse although we have not had this session on biodiversity, but it is really awesome and so exciting to see even these programs that come up on National Geographic. So, much of biodiversity and so much of beauty around nature manages to do all that through photosynthesis what is the what is the engine that drives this entire biosphere it is solar conversion of solar energy through photosynthesis and photosynthesis efficiencies are very low. So, with just a couple of percent of efficiency nature has been able to do these wonders and it is truly a miracle if you really sometimes we just see a tree or a plant and we think it is just a tree or just a plant, but we do not see the miracle that it actually is it is really amazing if you actually try to study it it is so amazing. So, if nature is able to do such great miracles with photosynthetic conversion efficiencies of hardly a couple of percent and if you you know basically distribute it over the 24 hour cycle then it would be less than 1 percent. So, with such poor efficiencies nature is able to do all this and it is also able to store solar energy in the form of chemical energy. So, it has actually achieved breakthroughs and we are living examples of those breakthroughs plants and animals and we too we are products of that biosphere which again indirectly everything is driven or powered by the by solar energy. So, if we have in fact done better we have done much better our solar cell efficiencies are very high. So, really speaking there should not be a problem we just need to develop technology that is adequate for our purpose. So, what I am trying to say is the present setbacks are not show stoppers there are there are bound to be ways we can learn from nature we can learn from our experience and we can bank on innovation. Now, the intermittent and poor predictability means that if we have to large penetration of these continuous or renewable energy forms into our energy mix by a large penetration I mean they should have large larger shares in the in the energy mix then we must integrate it with some storage and there is no easy way of storing electricity on a very large scale. The batteries and all that might be okay for your home, but even for your home they are pretty expensive. So, they are definitely not practical at a utility scale utility is the grid of the city or the state or whatever. There are more barriers. So, what we are looking at is we are looking at barriers for these alternative energy forms and they are intermittent the predictability diffuseness lack of available and efficient storage. Then there are commercial and governmental factors government subsidies and support for conventional energy forms is very high whereas for the alternate energy is not comparable. There is a in 2013 the world energy outlook of 2014 says that up until 2013 the fossil fuel subsidies were four times that of the subsidies given to renewable energy. So, if you subsidize the conventional energy forms and you do not adequately subsidize this then it is not a level playing field then the renewable energy will never be able to compete as it is they have their share of problems and the fossil fuels are not internalizing the environmental and the social costs. Yesterday I made a mention of internalizing and externalizing of costs. So, if the social and the environmental costs are included in the price of electricity then the price of fossil based energy would actually increase. So, if the fossil based energy becomes more expensive then comparatively solar energy would be at par or cheaper. So, all energy forms in my opinion should internalize their costs the social and environmental costs and then let us find out which is really cheap. There is no reason to artificially reduce the cost by subsidizing it or externalizing the costs. There is another barrier which I had mentioned that the grid presently is not capable of handling the high variability that is associated with the renewable energy forms and many major breakthroughs have to happen over there. Lot of government spending will be required I think from what I hear the present government knows about this problem and they are at it we have to still see whether it works out or not. So, demand response is whenever there is a demand for electricity generation should be stepped up or maybe some adjustments need to be made in order to supply that demand. So, this shows how there are various power plants over here and there are various load centers over here and the power plants are some of them are stepped down in their production, some run at low capacity factor, some run at high capacity factor and that is dynamically changed in order to meet the needs. This is an example of the daily load curve and this seems to be an urban kind of curve where you see that there is this is early morning when you probably turn on your water heaters and some lights. So, you have some peak over here during the midday there is a relatively steady load maybe partly industrial partly commercial and some minimum household and in the evening there is a huge lighting load. So, this may be due to light lighting. So, the grid is supposed to take care of that. Now, in order to do that I said we need utility scale storage. So, we have two videos over here and which demonstrate two ways of storing electricity which comes from the variable renewable energy sources. So, can we have this video please. But what we saw over here is that whenever the wind is blowing the electricity that is generated if it is not required right there and then if there is no demand for it then it can be used to pump water from a low level reservoir to a high level reservoir. So, that is so the extra energy generated by the wind gets stored and when the wind is not blowing and you require energy the same water is let out from the high level reservoir through turbines to generate electricity and serve the demand. So, this is one concept and it is being used in it is being planned for Europe and they already have it in a big way. The second way is to store it as thermal energy and again as I said the thermal energy will be converted back into electricity on demand so that a solar thermal plant can be operated 24 hours whereas with if you have PV then storing the electricity becomes a major issue. So, on a small scale you can use batteries or some people are even working on super capacitors but that is all for small scale not for utility scale. For utility scale this is one pump storage is one good idea and thermal storage is another good idea. So, let us watch this video on solar thermal storage. So, this is the issue related to the problem I said that the base load power has to be provided by some reliable energy source which presently I think only nuclear and coal are maybe they are up to that point. Geothermal in some places again is also reliable for that. So, that base load power needs to be provided and then there are peaking plants which operate only sometime. So, if this technology actually makes it big then it can even provide base load power through solar that is something very exciting. So, this is what so if you have the same load profile that I showed you this is for several days. So, this is one day and then the night and then the second day and then the night and so on and so forth. So, this is for the month of August. So, if this is the load profile then you have to have over here you have the different sources of energy that are listed. So, for hydroelectric also you need some amount of water that must continuously flow through. So, that is provided and then there is coal and then there is nuclear and all these various things which are all building up to serve that demand. So, this load profile is served by the various generating plants and the gas fired and the oil fired plants are very effective in providing that peaking power. Now, we are talking about turning off or reducing the production of one energy source and increasing the production of another all at the drop of a hat is not so easy. So, that requires major reforms in the grid and there are some technical components also that have to be improved. For example, communications have to be integrated with the power grid that is what is called as a smart grid. The in general you should be in a position to shuttle large quantities of power from one state to another. In Tamil Nadu there are some places where there is lot of wind power generation, but again that is not all year round it is not constant all year round. So, when the wind is blowing that is when that power is available and it needs to be shuttled to some other state and then borrow use electricity from that state when there is no production. So, all these features require a smart grid and unless we have that accommodating these highly variable alternate energy forms like solar and wind is not possible and even if there is a smart grid accommodating very large quantities of variable solar and wind power may be a very big challenge to do. So, for now some quantity of the conventional forms is required, but since these technologies are they have a far smaller environmental footprint they can be encouraged to come up to and develop. So, investments and research in these areas should definitely be done so that these forms are not killed in the race. Now there are many people who are very excited about bioenergy. Bioenergy is renewable biomass is renewable. See biomass is a classic example when you harvest it gets exhausted, but it grows again. So, that is an example of renewable source. So, it is renewable, but the entire biomass that is available cannot be used because if you it is part of the biosphere. The biosphere has to I think yesterday I gave an example. If there is a mango tree you can harvest only the mangoes. If you harvest the leaves and the wood also then you do not have a tree anymore. So, we can only use parts of it some agricultural residue. So, people say that there is no harm in using agricultural residue because you have the grain, the food grains that you take that is for food and then what do you do with the straw? The straw is not useful anyway. No, it is not so. It is useful. It is useful for fodder. It is useful to make manure. What comes out from the soil must go back into the soil. If it does not go back into the soil, the soil's fertility will decline over a period. So, there is a limit of how much even if it is agricultural residue, even if it is forestry waste, there is a limit to how much you can use. And it is not that biomass does not have any alternative applications. There are alternative applications. I just give you examples of fodder, manure, composting. These are alternative uses are there. So, there is only a smaller potential than we normally think. There have been good estimates of how much is the renewable or the how much of this biomass can be used. There have been good estimates of how much is the surplus biomass that can be used. In any case, these energy crops being planted on agricultural land is in my opinion not acceptable for a country like India where we have so many people who are below the poverty line and who are facing starvation. Particularly, if they are irrigated lands, on irrigated lands energy crop should definitely not be used because food takes priority over energy. Feeding a person is more important than feeding your motor car. So, in the selected places where there is excess biomass, particularly from your urban solid waste, that can be converted into fuels. In fact, in many places including our department in Amruta, we are working on these biofuels. There are interesting technologies. There are the biodiesel is something most people are familiar with but that requires an oil yielding plant and then you convert that oil into diesel. But there are other technologies where you do not require an oil yielding plant. You can just take in about any biomass or even waste plastic for that matter and using pyrolysis technologies or reformation, you can convert them into synthesis gas which is carbon monoxide and hydrogen. And synthesis gas allows you to do some very interesting chemistry. There is something called as the fissure tropes synthesis which allows you to synthesize fuels of your choice. So, with you know you can make diesel like fuels, you can make methane, you can make any others also. So, this allows you to synthesize any liquid or gaseous fuel of your choice from starting from synthesis gas. Synthesis gas by itself can also be burned in engines with maybe some minor modifications. But synthesis gas because it has carbon monoxide, there may be a toxicity risk. So, that is one of the big issues with that. Biomass can also be used for hydrogen production. So, some people are talking about the hydrogen economy. I am a bit skeptical about the hydrogen economy. I do not know. So, I think we will have to either consult the astrologer or wait for time to reveal. But the hydrogen in order to one of the good ways of making hydrogen is through synthesis gas and followed by a water gas shift to make hydrogen. So, there are nice technologies extremely interesting for chemical engineers, even mechanical engineers many nice things to do. And in fact, research should go on in this area because solar and wind is fine. But again, there is somebody I think in one of the I think in on Moodle or somewhere somebody posed a question about the transportation energy requirements. And transportation energy requirements are very high. In fact, in the among the end use sectors I think it is almost one-third of the energy. If I may be wrong, but something like one-third of the energy or total energy consumption is actually for transportation. And transportation using hydrocarbon fuels is a great idea in terms of energy density. Any of the hydrogen storage technologies or even your battery storage technologies, the energy density that you get is much lower than chemical storage. Chemical storage is the energy stored in chemical bonds of carbon and hydrogen and possibly oxygen also. There are some oxygenated fuels also. So, the chemical storage is actually a good way. And if we want to migrate away from fossil fuels, then bioenergy or biofuels are a nice idea. But again, maybe we do not have as much of biomass energy to meet the entire demand. So, some caution is required. If we can develop electric vehicles, then that would be great. But if you have to develop electric vehicles, then there has to be a storage technology and electrical storage technology. So, the battery technology or a supercapacitor technology has to come up to speed or you again store it in chemical energy and convert it through a fuel cell, something like that. Many of these approaches are being investigated all over the world and there have been maybe not major breakthroughs, but small breakthroughs in many many places and people who are doing research in this area, it is really very interesting. So, if you are interested, please go headlong into that research. The country needs such research and the world also needs this research. So, plenty of stuff to do in this area. I have just summarized the some of the bioenergy technologies. I think the easiest is direct combustion in the sugarcane industry. For instance, the bagasse surplus biomass is used to partly supplement the boiler fuel. So, you can use it for direct combustion. In pyrolysis related technologies, there are three types of fuels that you can potentially produce. One is solid char. You can make these fuel briquettes out of the char also. You can make liquid fuel. It is called as pyrolysis oil, but pyrolysis oil may be an adequate substitute for furnace oil, but it may not be engine grade. So, you could pyrolysis oil or wood oil as they call it is not suitable to directly put into your engine, you will damage it. So, may some other processes may be required to bring it up to that. The third is biomass gasification. You can convert it into synthesis gas and this with this sin gas, it is possible to synthesize liquid fuels through a fissure tropes process. There is also steam reformation biomass can be reformed by the application of high temperature steam that is one thing that will give high hydrogen yields, but then it becomes endothermic. There is biodiesel. So, that is you start with some oil which is derived from plants or some plant product, some seeds, oil seeds and it is transesterified to become biodiesel. There is another very common old technology, but it is not to be neglected in any way that is biogas, biomethanation. There are many other technologies. There are lots of innovations in this area which will improve the yields. For instance, because I am in a although I am a material science engineer actually by training, but I work in a chemical engineering department. So, some of my colleagues, they are discussing about different designs of biogas reactors. The reactors, the conventional kind that we see in rural places that is not the only way or the best way. There are better designs, chemical engineers specialize in reactor designs. So, if those some of those concepts like fluidized bed or similar technologies are used for biogas within a much smaller space, you can get higher yields in a smaller residence time also. Then there is not only methane which is biogas, but you can also get bio ethanol through similar fermentation techniques. Now, I want to show you this video and there is a reason why I want to show you this video other than there are so many videos and so many so much of reading material on pyrolysis and these technologies, but I particularly like this one and the reason I like this one is with this one technology they are doing so many interesting things. I want you to make a note of what all they are achieving and right after the video I will probably ask people what are all the things that they are using, that they are doing in this technology. I will just give you a hint this the video is shot next to a smoke stack of a power generation plant. So, they are doing something related to the smoke stack, smoke stack is nothing but the chimney. So, they are doing something with the exhaust coming from a conventional energy generation. So, I want you to pay attention, pay keen attention to that and tell me what are all the various innovative things that they are doing in this. So, what do you think of it? Jabalpur Engineering College. The video which we have was fabulous and more we excited that last energy drink. Yeah. So, we would like to go for that kind of test this is very means enhancement of the information and this is quite interesting. It is going in a nice manner moving ahead, very nice. Sure. So, can you tell maybe two or three things that you find are very innovative about that project? Yes, one thing that the carbon is actually going into the atmosphere, it is polluting, they are capturing once again. So, like a filtration and this is at the moment like a magic that one thing which is a wasteful material and we are converting it into back and we are reusing it. So, it is a byproduct by the production through this power plant, the byproduct as well we are getting. We are using the flue gases which are going as a waste into the atmosphere, they are doing some useful work for us and this way we this is the enhanced use of the energy. Awesome. Thank you very much. I suppose. That is very well said. So, you know that that technology is doing many things. It is capturing the carbon from the smoke stack. So, it is a way of carbon capture and it is producing these algae which can be dried and stored indefinitely and that is a value added product you could select the algae to be edible also. The same algae if required can be used for hydrogen production. Then it is also a way of removing the nitrogen oxide. So, they actually act as nutrient to the algae. So, the as nitrates you know they fertilize the algae. The growth of the algae also can be sped up a little bit by increasing the concentration. So, they are not actually using all the smoke stack carbon CO2. They are I think they are they are enriching the to about 1 percent or so in in air. So, it is only a small quantity of CO2 that they are putting in, but that that enhances the photosynthesis it increases the biomass output. So, so many nice things that are that are done in one system. So, I think we if we get creative and I am sure that you can if these people were able to find this nice innovative technology with 4000 great minds at work I think we can achieve much more than this. Okay now I am I just want to quickly recap what we have learned so far. What we have learned so far is that all the major conventional sources of energy have unacceptable environmental and social costs and there is a there is an urgent need for benign alternatives. Now the benign alternatives exist solar, wind, geothermal, bioenergy these are all present they are abundant we generally have the technology to harness them, but there are important barriers and because there are barriers we engineers are in business. So, it is I do not think we should look at it negatively I think it is positive it means that we are required. There are some technological barriers there are some other kinds of barriers. Now a sudden transition is impossible, sudden transition is not possible and it is it nobody is recommending that sudden transition, but we must have a goal we must have a vision and we must gradually work towards it if we if we even if we go into denial and do not even do not even acknowledge the possibility of a of an alternate energy system then there is no hope. So, I do not think we should take that path I think it is it is important to to to even dream it is important to have a vision and we will gradually we have to approach that. So, some amount of conventional sources will be required to meet the demand, but we must be very keen and we must be very sincere about pacing them out in the interest of the environment. So, I told you that sustainability is is not merely taking a set of available technologies to serve the market demand as if the market demand is something really sacred. The the market demand is placed by consumers and we are consumers too. So, it is it is important for us to learn to live within our means and learn to live within the means of the planet. So, if we are able to control our need or modify not necessarily control modify it a little bit. So, as to accommodate others other other forms of life and other human beings if we are able to accommodate that then we are on the path of sustainable development otherwise we are we are just dreaming. I mean we are we are we are saying something and we are doing something else. So, sustainability has all these various dimensions. Now, till then until until those that development that R and D in renewable energy form forms happen we need to save energy and energy saved is is as good as energy generated and saving energy it does not does not take any fantastic technology all you need to do is as a consumer you have to be conscious about it. At an industrial level many more things have to be done and I will just point out a few things, but what we have to do is we have to look identify the most energy intensive end uses and the efficiency measures if we initially we should implement the efficiency measures in the most energy intensive end uses and later on we can spread them elsewhere. I will give you an example making spending 1 million dollars to do research to make battery charges more efficient. Battery charges do not consume such a whole huge lot of energy to spend 1 million dollars to make them slightly more efficient is not going to positively impact the energy seen so much. On the contrary in making a combustion process more efficient would probably yield more benefits. So, that is what I mean by targeting the energy intensive. So, we have the industrial sector which consumes roughly 30 percent residential about 22 and transportation 28 I told you that was very important. Now if we take them sector by sector and see what all efficiency measures we can do the industry which is the largest energy consuming sector within the industry why do they need energy? They need energy to manufacture products that we purchase. So, if we purchase products only based upon our need and not merely to satisfy any whim or fancy of ours then the consumption if the consumption becomes reasonable then unnecessary production will also not happen and the energy demand may come down a little bit. There is embodied energy I gave you examples of embodied water I could have a table with embodied energy also, but I do not have it in the slide. But I think you have a fertile imagination so use it buying less and buying and wasting less is extremely important one of the most important measures that we can have. Now in many industrial processes where heating and cooling is required particularly in the process industry solar thermal energy is already quite mature and cost competitive. So, that can simply be used I told you that with an absorption chilling kind of arrangement solar heat can be easily converted into cooling. So, where in processes that require chilled water for example, milk pasteurization and things like that you can use solar heat to produce cooling. Solar absorption based solar air conditioners are also commercial there are not too many companies doing that, but there are companies which are having products for that. There is another important area which is called as heat integration. If there is one waste heat source which is giving out waste heat at let us say 100 degree Celsius it can be used to preheat a feed stream in a process where there are many output streams and there are many input streams a waste any output stream which is hot and which needs to be cooled can merely be connected through a heat exchanger to a cold stream and the cold stream will get warmed up. So, this is heat integration this can be done on an industrial scale in a refinery you may have so many hot streams and so many cold streams. So, in exactly in which is the most efficient combination depending on the temperatures and the flow rate and the heat flux you can design it and this technology is extremely important for the chemical and the process industry. It is being done all the petrochemical giants and the chemical giants they know about this and they are working at it this is something very useful the benefit is that it can give you energy savings which can be very high and with relatively less infrastructure cost the payback periods can be as little as few weeks and sometimes maybe a couple of years but not considerably more than that. So, you can actually reap lots of benefits this is combined heat and power this is cogeneration this tells you in order to get the same amount of electricity and heating you can run a power plant and get the electricity and run a separate boiler to generate the heat, but you would be using 147 units of fuel. But if you have a combined heat and power or cogeneration system you would need only 100 units of fuel to serve the same demand and in many industrial processes including our homes also you require not only electricity, but you also require heating cooling. So, in that sense cogeneration, tri generation, multi generation is extremely important and it can give you major benefits this is again another diagram of CHP this is a little bit of the internal functioning how you can apply that. Out of the box thinking I had mentioned about that. So, this is one example of out of the box thinking you can have these green buildings which require very less energy to begin with I have you saw the Auroville video and in that you saw the house by one gentleman I actually visited his house and it was the month of April in Pondicherry. Now, Pondicherry has weather almost identical to Chennai it is extremely hot in the month of April it is really I mean the heat is oppressive and we walked all the way and we were like sweating and all that and we entered his house and in his house I distinctly remember there was not even a fan and it was very comfortable I was so surprised. So, it was because he had designed the house so beautifully. So, he had some layers of some insulating tiles made from some porous tiles. So, he had that and then he used he had a high thermal mass. So, during the night time you know he would open the doors and windows allow that to his entire house to cool and during the day time when it heats up he would close the doors and windows so that the coolness kind of remains inside. So, very nice but this is another way by which you can make green buildings and not require so much energy. I said that there is we should not treat the increasing energy demand as something sacred it is driven by consumers and the consumers can change their ways. If you do not require energy then the energy need not be made or less energy needs to be produced. So, green roofs are one way by which you can reduce building heat gain you can you can produce some output out of that there are people who have terrace gardens green roofs are different from terrace gardens, but they are quite similar you can produce some fruits vegetables you using wastewater. So, you reduce the building heat gain you do not require as much of air conditioning or fans to be continuously on you can have a better more comfortable lifestyle. These two videos are really excellent, but unfortunately we have run out of time this talks about completely self-contained eco houses. So, they are independent in water they are self-sufficient in water they are self-sufficient in energy they use only recycled materials for constructing the house you know what they are made up of I mean who would guess they are made out of used tires used tires are basically you fill mud in into these used tires and then there is only a surface plaster. So, you have these thick walls made out of plaster and they many other recycled materials are used for the construction and there are again there are plants growing inside inside the house the water is recycled the gray water recycling similar to what we saw that is all have part of it happens indoors part of it happens outdoors there is rain water harvesting there is a wind turbine there is a an energy module which takes from the solar panels and a small wind turbine it integrates all of that into one kind energy module and supplies that electricity inside and the interiors are so beautiful you will really love that. So, finally it comes down to us you know what can we do and we are we are all qualified people and in our own field there are many things we can do if you are a chemical engineer I have a list of things that you can do in order to address this problem industrial symbiosis process integration pinch technology cogeneration these are all things which will save enormous quantities of energy enormous quantities of waste avoidance waste will be avoided and pyrolysis gasification we can make a lot of fuel available things like that. If you are a mechanical engineer there are again many things that you can do if you are a material scientist there are there is photovoltaics leds nanostructured catalysts we had kind of a site discussion yesterday about nanotechnology based water purification yes that is required I did not say that it is not required I said that that is we should not stop at that. So, you can definitely contribute to that there are ultra capacitors there are batteries and so many other technologies that are there in the overall field of energy as a consumer we are all consumers and there are so many things that we can do simply minimizing unnecessary purchases is actually the the easiest and the best thing you can do then of course you know avoiding air conditioners and preferring fans or desert coolers people from places like Bombay will say that no we cannot avoid air conditioners because desert coolers will not work in Bombay true they will not work in Bombay but in combination with a desiccant they will work just fine there are there are desiccant based air conditioning technologies where if the air is too humid then it it will not evaporate I mean water will not evaporate so much so it will not provide cooling but if you can reduce the relative humidity of the water by absorbing it in a desiccant and then the air can actually get cooler by a few degrees and it is only few degrees that we require most most of us Indians we are climatized to a hot tropical climate we are born in that and it's it's fun to be in a tropical climate it's not really very interesting to be in a cold climate where you have to think 10 times before stepping out of of your home and a few minutes out in the cold and you could die so it's actually good to be in a tropical climate it's okay to sweat once in a while so many many technologies are there that will that will assist us in living in a comfortable manner by with small energy inputs CFLs, LEDs you are you are aware of that keeping your computer in shutdown hibernate modes if you are building a house consider building an eco house there is so much information out there and you can go and visit places where they have it and I can tell you there is a 90 plus percent chance that you will fall in love with these eco houses more than a conventional house you will like them much better for short distances using bicycles and public transportation rather than four wheelers instead of air travel and private cars you know try to use trains or other public transportation and I have a long list you can add to that list so that's all from me for now so have a nice break