 Okay, good morning everyone. Okay, so today's topic is energy resources. Now, this again is a very big topic. I am only, I mean as much time as we have, we can probably only have an overview. But I am going to maybe discuss some of the conventional energies, the associated risk with them and the depletion that we are facing, the related global warming problem. And I am going to maybe share with you a few good ideas which are, we don't know really, it's hard to say at this point, you know, how the world's energy systems are going to, which direction they are going to take. We'll have to wait and see. But there are some very good ideas in which I thought I'd share with you. So hopefully you'll like at least some of them. Okay, so this is the outline. The first topic is units and terms because I understand that many of the environmental science teachers are not from an engineering background and then it's a little hard for them to navigate through the various units and the terms that are used. So I have tried to collect a bunch of the commonly used terms, the terminology as well as the units. And hopefully this will be a place you can go to whenever you are confused. But again on the open internet, you have all these various conversion tools and whatnot. So really that's not a big problem. Okay, so I have, and I'm not going to go through all these slides, but I'll just explain to you that there are these energy units, there are power units, there are heating values of fuels and then there is the higher heating value and the lower heating value that may not be very relevant to people who are not from the mechanical sciences. So people who are from computer science background or biotechnology and all that may find these terms and things not so relevant. But anyway, I still have it over there. Then there is the energy content, all these fossil fuels, they have a certain energy content. So we'd like to know per unit mass how much energy they can give. So I have listed by fuel, what is the heating values of these fuels. And then there is also a list of the carbon content of various fuels. So in other words, this also is kind of important because if you take coal for instance, which has, which is mostly carbon to generate the same amount of energy if you are using coal, then you would be emitting more CO2. Whereas if you were using methane to generate the same amount of energy, you would be emitting less carbon dioxide. So the choice even within the fossil fuels, in general, all fossil fuels are bad for global warming, but within them choosing between coal and natural gas, there is quite a significant difference because you see with natural gas methane, it is about 14 metric tons of carbon per terajoule whereas for coal it is 25. So that is quite a significant difference. Maybe people who are in the field of engineering, they can explain these things. You could read through these slides and then explain to your students some relevant aspects. The second topic which actually is beginning of this discussion is the energy resources that we currently depend upon. And what are the, how much of these resources exist? What are the risks associated with using them? And the fact that being mostly fossil fuels, they are going to get depleted. So what are the timelines when we can expect their depletion at a certain rate? So getting into this discussion, this is stuff that you probably learnt in school. There are renewable resources and non-renewable resources. Renewable resources are those which actually get exhausted but can be replenished by natural processes. Solar and wind are not renewable in that sense. They are perpetual. They are always there. They do not get exhausted and then replenished. Fresh water is an example of something that gets depleted but gets replenished or biomass wood for instance is renewable because wood grows. You can harvest some wood and then it gets exhausted temporarily and then it grows back. So that is renewable. So that is why I have three categories over here. I have perpetual or continuous in which you know solar, wind, geothermal, they come into that. And then the renewable which is something that gets depleted but over a time span that is short enough as compared to the human lifespan. Over a short enough period, they get renewed. And then there are the non-renewable resources which takes, which fossil fuels in that sense, you can say that they are also renewable but it takes millions of years to get renewed. So over a, compared to the human lifespan, they are non-renewable. So it turns out that we are having this discussion because we are in the middle of a global energy crisis which is worsening day by day. And how do we define the crisis? Crisis means we are trapped. There is no easy way out. So in order to explain this, I have put together a few points which in my opinion adequately summarize the situation we are in. The first point is that we have a near total dependence on fossil fuels which are unsustainable energy sources and then there are other unsustainable energy sources also. So humanity has a near total dependence on these unsustainable energy sources. Now the use of these resources, these non-renewable, unsustainable energy sources is leading to an irreversible damage towards life support system. So what is the earth's life support system? The sense in which I use this phrase over here is related to the very beginning when I spoke about sustainable development and the Gaia theory. So these various interacting systems which maintain the biosphere and enable us to provide all the environmental functions to us. So it is that earth's life support system that I am referring to. So use of these unsustainable energy sources is causing irreversible damage to that support system. And as manifestations of that, of those impacts on nature, we are seeing global warming, various kinds of pollution, the related health problems and what not. Now these unsustainable energy sources, it is not that they are going to last forever being non-renewable, they are going to get exhausted. So some of these reserves are severely depleted and many of them are going to get depleted over a matter of several decades. It is very obvious that we cannot rely on these forms for too long. Now to add to this the rate of consumption of energy is increasing at an alarming rate. The demand is increasing and in order to meet that demand if we have to extract more and more of these already depleting sources then we are in a very precarious situation. Again if you use those energy resources then we are risking not only faster depletion but we are also certainly going to face very serious environmental impacts. You may say that this by itself is not a problem because many renewable or environmentally friendly forms of energy do exist. Agreed they do exist but presently their share in the energy portfolio is very less. In other words we are using hardly maybe less than a percent or so of renewable energy forms and more of the non-renewable. This is basically a summary slide and in the following slides I will only add detail to this discussion. Let us get into it. The first point was that we have a near total dependence on environmentally unsustainable technologies. So this is the world energy consumption by source. This is 2012 data which is recent enough and you see that the fossil fuel dependence is something like 87 percent and you know there are relatively smaller shares of nuclear hydro and some other renewable sources. So coal, oil, natural gas form the major share. If you look at India the scene is not very different. We again have a major dependence on fossil fuels up to 91 percent and so over here is the primary energy consumption. Over here is India's power generation. So which source of energy we use to generate our electricity? So it is again very heavily dominated by the fossil fuels. You have coal having a 60 percent share and then a little bit of the others. Now I am showing this slide to emphasize the fact that the electrification rate in India is low. It means that there is the demand for electricity is very high and it is going to rise. The overall electrification rate being 65 odd percent maybe the data may be a few years out of date but I think it still conveys the message. It means that our demand is going to increase. So if we have to generate more electricity it means we have to going back one slide we have to depend more on these environmentally damaging technologies. Now for what do we use the electricity? Once the electricity is generated in India what do we use it for? It turns out that we are we are using it for mainly for industry domestic and agriculture. So these are the main end use sectors of electricity in India. The commercial sector is relatively small and then 7 percent is other. So it means that these are all very essential areas in which the electricity is being used. It is not like we are using it for something that is non-essential. So the electricity is being used for essential things and that demand is going to rise and we depend in a major way on fossil fuels. So meeting that demand directly means more and more consumption of these fossil fuels. This is just some detail but maybe of interest to some people and maybe to engineers. There is a I am going to introduce the term of the base load energy and peaking energy. The electricity grid is the electrical distribution system which supplies electricity to all of us. Now that is supplied by electricity through various sources. So you may have a hydroelectric station, a nuclear power plant, coal fired power plant, a gas fired power plant. All of them are connected to the same grid. All of them are supplying to the same grid and then we are consuming that electricity from the grid. So there needs to be a certain steady generation. Now coal and nuclear very ably provide that base load energy and in some parts of the day and I am going to show you with graphs little while later. At some points in the day there is an extra need for energy. So that extra need for energy for a short duration is provided by what are called as peaking plants. So these are these are plants which will be turned on only for a certain amount of time in order to meet that demand. So the base load energy deficit in India on an average is 5.1 percent but it varies in the southern grid it is about 12 percent. In the north eastern grid it is about 17 percent for the base load and for peaking the peaking shortage on an average is 2 percent. But again in the southern grid peaking shortage is very high and in the north east also it is pretty high. So it varies from region to region some places are well off and the others are not so well off. So this graph shows how the energy demand in India is increasing and this is also representative of many countries in the world. So world over the trend is similar. Coming back to that summary slide I told you that these if we are depending on fossil fuels then there are there is a risk of depletion. For fossil fuels see nuclear and hydropower are the conventional sources. Now fossil fuels are we know they are non-renewable and oil is depleting very rapidly. There is some concept called as peak oil which I will just show you in a moment and for coal mining coal mining comes with very serious impacts and then there is the fly ash and the bottom ash waste problem apart from global warming. So there are so many problems but coal again is also limited in quantity although it is much more compared to oil. Uranium also is limited, thorium will last somewhat longer. Reprocessing is a great idea it can create more nuclear fuel and make the available reserves fossil reserves last much longer. Fusion technology we know is quite distant yet. Hydropower the issues are that many large dams have already been constructed many of these river systems they already have many dams and more dams many more dams might not be possible maybe a few more dams would be possible but maybe not in a very big way because of the social impacts. The sad part is we cannot even consume the remaining fossil fuels. So you may say that if we if the reserves of fossil fuels are depleting at least let us enjoy while it lasts even that is not going to work out because if we try to consume the existing reserves of these fossil fuels it is going to harm the environment and lead to a lot of other social problems also. So what are what are those issues? So again for fossil fuels problems which are pretty well known are the greenhouse gas emissions and climate change. There is also pollution of air, land and water particularly with coal mining there is a lot of pollution problem. What are the issues with nuclear? You have major accidents which are very rare but when they when they happen they are extremely scary. There are minor accidental releases of radioactive materials then there is a nuclear waste problem and then there are the costs of decommissioning and cleanup. When things do happen it is major cleanup that is required and then old reactors have to be decommissioned. So that again is an issue. With hydropower the risks and the costs include land submergence. I yesterday I mentioned about disruption of riverine ecosystems and flood plain agriculture. The ousties the people who are ousted or basically asked to go from their land those people not all of them get compensated particularly if they are not land owners. If they are not land owners then the government does not compensate them adequately or has not historically has not compensated them adequately and this is not only in India but all over the world. As a result you will find these major public agitations and there are if you go to YouTube there are very very moving videos on the condition of these uncompensated ousties. There are people were people staged satyagrahas and they you know basically they were ready to drown themselves when the dam waters rose. So really really pathetic to watch. So we have to be a little sensitive about that development is important but development at somebody else's cost is not development really. So that was a summary I will quickly take a short run through fossil fuels and what are their issues specifically. So how do we use fossil fuels? We use it in mainly three ways. The first one is you burn the fossil fuel in an engine I mean you create rotary motion and you can use it either for transportation or for generating electricity on a small scale. The second use is that you burn the fuel for heat for heating applications. And the third one is you make you heat it makes steam in a boiler, rotate turbines, operate generators, generate electrical energy and distribute it via the grid. So these are the common ways that we use fossil fuels. Now very large amounts of electricity can be generated once the entire infrastructure has been set up. So the let us say from the coal mine the railway tracks are laid to the thermal power plant then you know the mining will continuously supply the fuel necessary for the plant and then it can be in operation you know 24 7. So once everything is set up it is quite reliable and transporting coal, oil and gas there are there are different modes of gas can be transported through pipelines as well as compressed tanks and what not. But once all the infrastructure is developed then it is a fairly reliable system fairly reliable and you get good quality power it is not unreliable. So how does it all begin in the case of petroleum you get crude oil and that is deep within the earth's crust and that is extracted some there may be it can either be on land or there may be offshore oil rigs and you extract the oil there are lots of refining steps that happen to finally yield the fuel that we use like petrol or diesel or what not. Now it turns out that the oil reserves are depleting. So I had mentioned the depletion risks there is something this concept called as the peak oil crisis. So what is that when so the the curve in the in the dark line that you see the bell shaped kind of curve also known as the Hubbard curve is is the total daily oil production for a and it is it is plotted against time. So number of years what you see in in the slightly fainter lines are the is the production from each individual well. So this curve can be plotted for a region or it can be plotted for the entire world and each individual well once once it is dug it starts producing and it gives a stable production for several years and then its production kind of declines but by then a new well is drilled and that produces and then its production declines. If you add up all of these all these the production from each individual well then what you get is is this curve this curve looks more or less symmetrical. So if you are at this peak it means that half the oil on the left hand side which existed half the oil reserve of that region has been already exhausted and then on the production is going to decline. So if the production is going to decline we know that world over energy demand is only increasing it is not there are no signs of it reducing. So if the if the global energy demand is increasing and your supply suddenly reduces then what is going to happen is high prices. So we might be at this peak some say we will probably reach it shortly some say some studies say that we have already passed it and some say that we are near about the peak. So whichever the case may be in the future the production is not going to be that high there may be arguments on how long it may last but I do not think there is fundamentally an argument of whether or not it is going to last forever. So this is actual data on the left hand side and it is classified by the fuel type. So this shows a similar curve what is on the right side of this dotted line and the year 2004 what is on the right side of that is projected. So on the left hand side is the actual data. Now these burning of these fossil fuels we know that is increasing the CO2 emissions leading to climate change and we will have a separate session on climate change by another faculty member. This is just a general graph showing which are the major oil producers and which are consumers. So you take Saudi Arabia for instance the maroon or brown bar indicates its consumption and the grey bar indicates its production. So Saudi Arabia produces a lot of oil and consumes relatively smaller part. On the contrary you take a country like India it produces a small quantity of oil but uses much larger quantity of oil. So which means that the rest of the oil has to be imported. This curve and the next even this one discusses about which countries have so far historically which are the countries which have been emitting the maximum quantity of greenhouse gases and it turns out that the cumulative emissions from 1751 to 2009 US has is probably the single largest share in the greenhouse gas emissions. Europe is also quite a significant quantity and then China is also big compared to that India historically over this time period has not emitted significantly but things are changing now. Now if you take only 2009 the annual emissions then you see that China's share is bigger than US and India's share is also much larger. So in future it is going to be assuming that the developed countries will not consume much more energy but the developing countries are going to consume a lot of energy and the demand is going to continue to rise. So far the way it is that India's per capita CO2 emission is very low. If you look at the per capita and then even projected to 2030 the per capita emission of CO2 is very low. Compared to the United States where the per capita CO2 emission is very very high. I mean it is several times of that of India but again we must remember that India's consumption is low but a large chunk of the population is below the poverty line. So if all of them have to have to come up above the poverty line and if even the middle class has aspirations to consume more and more then this might not hold you know it might increase and we have a very large population compared to compared to the United States. So if having such a large population the multiplying factor is very large. So the total emissions will be significant then. So if this oil we know about the peak oil crisis and oil being limited and it might run out. So why not turn to coal? There is plenty of coal. Yes there is plenty of coal. It has high energy content. It is an energy dense fuel. In other words in within a kilogram of coal there is a lot of energy. It is easy to transport and things like that. Now there are newer technologies like clean coal technology, gasification, reformation that are coming up which reduce the pollution to a large extent. But coal is associated with with many socio environmental problems. This is a photograph of a coal mine in Bihar and you see how it has completely destroyed the land. I mean it is a huge crater and ugly huge crater where once there was a forest. So these open pit mines are are a major environmental problem. There are the close pit mines where you have a you drill a shaft down and then you have these horizontal tunnels in which the mine workers go in and then they extract the coal. So they are they are somewhat better but then they are also prone to accidents because methane tends to accumulate in in those tunnels and then even even a pickaxe hit on on the mineral can ignite the methane and lead to a very serious accident. Okay coal obviously is associated with very high emissions of carbon dioxide and in the very early slides that I showed you the carbon content of coal is very high. So for the same amount of energy output coal will emit more carbon carbon dioxide as compared to diesel or petrol or natural gas. So according to some projections it may last about 50-60 years. If the current acceleration in its use continues it leads to lot of environmental damage and pollution from even heavy metals and some radioactive materials also. If the sulphur content of coal of a particular coal is high then it can lead to acid rain. There are instances where the groundwater and surface waters have also been polluted very significantly leading to lots of health problems for people around. The fly ash and the bottom ash again are a major concern. The coal fired power plants have been associated with lots of diseases and deaths of many people. So as I said you know flue gas desulfurization that is removal of the of the sulphur oxides from the exhaust. So all these are good technologies clean coal technologies they are they are good but again you cannot hide from the fact that invariably you are going to emit carbon dioxide. The carbon sequestration is definitely a good idea but again it has to work out and for some sequestration technologies what is the long term stability of that sequestration for if it is geological sequestration I mean what is the guarantee that it is not going to come out one fine day. What if there is an earthquake and earthquakes keep happening recently had earthquakes in Nepal. So I am a bit concerned about that. So if coal is bad then what about natural gas? Natural gas is supposed to be clean. Yes it is it is quite clean it once upon a time it was wasted during oil drilling because when you drill for oil and the natural gas which is accumulated in geologic formations that escapes out and then where you drill is that place may be far away from where energy is required. So there is no easy way to transport the natural gas to the place where it can be used and as a result it was just simply let out or flared. Flaring is just igniting that gas and simply burning it away. So the flaring is better than simply releasing methane because methane is a very potent greenhouse gas. So converting that methane into carbon dioxide is better but the best thing is to use it rather than simply waste that energy. Now there are public transportation vehicles that are required to run on compressed natural gas that is a good step it is a positive step. Some slight issues with natural gas are that its energy density is somewhat lower than definitely lower than coal, lower than petrol and diesel that is not such a significant problem with some minor modifications the vehicles can still run on it. Nitrogen oxide emissions continue to be a problem and the gas reserves again will probably last around 60 years according to some estimates. But as I said the global warming potential exists from two sources one is after combustion natural gas is carbon dioxide is obviously released to the atmosphere but even before combustion there are always leaks through pipelines and during handling some accidental leaks that happen. So if there is a if natural gas becomes the fuel of choice there is going to be some leak from those sources which affects the earth's climate ok. Now we have basically gone through most of the fossil fuels at least the major ones then there is a number of people who think that nuclear is the only option and for good reason there are some very strong points in favor of nuclear. What is generally thought is that these are nuclear can provide enormous quantities of very cheap energy with no emissions. It is true that it does not give any emissions of greenhouse gases there is there is some little bit of GHG emissions in the construction of nuclear power plants but I think that applies to every form of energy. So in generally the greenhouse the global warming potential of nuclear energy is very low. So we know how it works atoms are split the process of nuclear fission there are also concepts of nuclear fusion but we have not been able to make commercial reactors using fusion technology which we could but not there not there as yet. Common the most common source the nuclear fuel that is used is uranium and it is mined in various parts of the world and small quantities of uranium in a reactor can give very large quantities of energy. So there are some countries which which rely very heavily on nuclear for their electricity but in India the share of nuclear is much smaller and world over also it is not very large because there are relatively fewer countries in the world which have nuclear power. The costs of nuclear power generation are relatively cheap they are as roughly the same as coal and it does not produce carbon dioxide. So that is a very strong point. The other very strong point is that once the plant is in operation it is extremely reliable. So I talked about base load power nuclear probably is the best example of reliable round the clock base load power. But the disadvantage is that there are some very extreme risks associated with nuclear energy in general and and that they they come from the very closely related nuclear weapons weapons proliferation the handling of nuclear waste and possible accidents. So the nuclear industry probably in terms of safety is I think compared to the chemical industry it is by far better. But the problem is if something does go wrong and the nuclear waste is is going to last for an extremely long period of time. So I from the point of view of a human lifespan the there are many isotopes which are which have half lives of thousands of years. So they they remain in the environment and that is only the half life. So they remain in the environment for a very very long time. There are there are some isotopes which which decay much faster they have half lives of maybe days or a few years. So that that may be an acceptable kind of risk but with the long lived isotopes that is very different. So now you may think that the safety issue is quite exaggerated and that they have a very good track record. But it turns out that on the nuclear event scale there are the major accidents that have happened are the Fukushima disaster and the Chernobyl disaster where a lot of people have been exposed to to radiation and it is continuing Fukushima is still releasing radiation underground and to the ocean. So we do not know exactly what what the effects are going to be in the long run and in the long run as far as nuclear goes is you know many many half lives. So the some of the isotopes have already died down because they had very very short half lives. But then there are the long lived ones are a big problem. There have been nuclear plants which have which are quite notorious for several accidents and accidental releases of radioactive material that they had over the world and I have listed a few of them over here. So if you if you look at the worldwide accidents or some major accidents and some not so major accidents at power plants they are very small in number. So but they they have continued to happen even after we let us say that after Chernobyl in 1986 humanity probably learned its worst lesson but the accidents have continued even after that. So 57 percent of the accidents have happened in even the United States. It is not only like these accidents happen in Soviet China or something like that. So what I am trying to say is that the accidents are are unavoidable and they are they are bound to happen. The only issue is that the nuclear accident has unacceptable consequences whereas any other accident you know has may have implications for that generation but not for future generations. So there is a very strong issue of intergenerational ethics associated with the nuclear issue. Intergenerational meaning what gives us the moral right to destroy the environment or put the future generations the generations which are not even born today to put their lives in danger or to damage the environment for them. So these intergenerational ethical issues are are very common in the discussion of sustainability and sustainability involves the such issues. So I told you that many other accidents happen auto accidents happen in millions, chemical accidents happen quite frequently. The problem though is that the radioactivity related accidents can lay waste land for for thousands of years. I mean there is no possibility of people within within our human lifespan or within a matter of centuries which which is what we can normally imagine. There is no possibility of people colonizing that place again and the effects continue over generations. Now radioactive waste disposal has been planned very scientifically by the the nuclear industry and there are I will share some resources with you also on that but the the long lived isotopes will will remain a concern for a very long time and they they they normally vitrify the the radioactive waste and then they put it in these canisters the steel drums and then they they plan to geologically basically bury it very very deep but it turns out that they have no country has so far started doing that I mean the all this is planned and it is said to be operational in a matter of a couple of decades but so far this geological storage of long-term storage of nuclear waste has not been done. So while that has not been done there are there are other completely unethical things that that have happened and this is exactly with what the what the problem is that the planned and good ways are are yet to see fruition but the really unethical ways have have happened. This is an extreme case I mean it may not be the norm but this particular mafia clan was was paid by some countries state nuclear agencies to get rid of some drums filled with toxic and radioactive waste from advanced countries which we look up to and Somalia was the destination for dumping that waste and some of it has been dumped in the Mediterranean so they load up ships with these drums and simply sink the ship come back and claim insurance cover for that. So this is these unethical things are also there then more recently there are there is a threat of terrorist attacks and things like that. So there there is a clear intention to cause harm the what I am trying to get at is we need to probably look for systems that are inherently rugged and inherently more resilient to such issues. See there are natural disasters they are not in our control wrong intentions of human beings are also not in our control there are terrorists in the world we are living in a real world and terrorists are there and they are bound to attack. So having an energy system which is vulnerable to natural disasters vulnerable to human error vulnerable to deliberate intentional attacks is is not a secure system. So what is this physicist over here says that the future energy in a sustainable world for now let us leave some practical considerations aside let us think of a sustainable world maybe idealistic or whatever it is but let us imagine a sustainable world in that sustainable world is it better to design an energy infrastructure which is inherently resilient or is it better to design something that is vulnerable to attack vulnerable to natural disasters. So from that point of view it is better to have a decentralized system where it is very difficult for a terrorist to attack an entire country if they target a few nuclear installations they do not have to drop a nuclear bomb on you they just need to damage your nuclear reactors the radiation will spread. So this is and that is what happened with Fukushima due to a natural disaster now the tsunami was nobody had imagined that a tsunami would come or maybe they had imagined but they did not they did not think it would be that big. So tsunami hit India also so our fortunately our reactors did not have this problem but again you know accidents keep happening human error also happens Chernobyl there was a human error involved nobody did it deliberately but there was error so these things are unavoidable. So this is where I am actually getting to I am sure you are free to have your own opinion about the nuclear issue and some people do are staunch believers in nuclear energy and okay good for them but so I have some reading material and I will add some more about the pros and cons of nuclear energy you can it is a hyperlink you can you can click on it and then refer to it and then there are there is the world nuclear association also they have they have described it very well the way they plan to the long term storage of nuclear waste and things like that. There are some countries which want the storage to be retrievable so future generations if they want to use those waste for some purpose then they should have the ability to do that. So some countries want retrievable storage some countries do not want it retrievable because when it is not retrievable it is more secure okay. We looked at fossil fuels and we saw that there are problems then we looked at nuclear and we saw some of those problems. Hydroelectric is a renewable form of energy because you know water is renewed every year through the water cycle and you have the reservoirs that get filled up in the rainy season and then they get used up during the rest of the year. So hydroelectric is a renewable source of energy it is also a conventional form of energy we presently do use a lot of hydroelectric power. So why not simply scale that up there are issues the socio environmental issues which I have discussed with you but in general hydroelectric is a very good idea because it has once constructed it has low running costs there is no waste or pollution after the initial phase in the initial phase during submergence of land there may be methane emissions once functional it gives very high reliability the electricity is highly dispatchable. So dispatchable meaning it can be the production can be stepped up and stepped down at a very short notice to match the demand. So this is a very important advantage of that and in fact in a sustainable energy infrastructure hydroelectric can play a very important role and I am going to show you even a video and an animation on that. So this basically brings me to the to the end of this this session I know we have a little bit of time and I have something planned for that. Mepko Shlank Shivakashi yeah hi I would like to I would like to know what what you have written down in terms of some things that you you agree or plan to do related to the water issue. What is the difference between the perpetual resources and the energy resources? Okay renewable are things that get consumed but get replenished due to the various processes in the biosphere and perpetual is which is always there solar energy is always there. Mufakam Jha Hyderabad. Sir my question is generally we are using silicon plates to capture sunlight or solar energy what is the main reason behind using the silicon and one more question is what are the other alternatives apart from silicon? There are there are various technologies yes silicon solar cells are the the main technology for photovoltaics it has been around for a very long time but there are many other alternative technologies I will not get time to cover all that you can a simple search on the internet will pull up many things you have cadmium telluride you have dye sensitize solar cells you have copper indium gallium arsenide so many things are there many technologies are there. In our college we are having a permeable pavement for recharging the aquifers, groundwater aquifers and also in our home we are having percolation pit for recharging the aquifers with the rainwater we are planned to have in our college also this type of pit where the rainwater falls actually to the ground where it reaches to the ground these type of things actually recharges the aquifer so we will not have a scarcity during summer season right excellent. Do you remember that video I showed you about Bangalore the rooftop on Bangalore see how much that gentleman was able to do at least everybody each one of us can at least conserve the water usage right we can we can limit our water use we all get a water bill right so we know how many liters we are we are being charged for. With this activity this year we are not having any scarcity of water from our gore it is practical also this year we had a very good result with that percolation pit actually excellent that is very nice thank you thank you sir. Techno India Salt Lake Calcutta sir I would like to basically spread awareness among each and every individual in our area so that water is penned less if we belong to West Bengal where there is no dirt of water as such because we have the hoogle flowing by yes so we personally I also never have I mean the awareness is not enough when we enter the washroom we kind of accept that water is a free commodity like so if we can personally like spread this awareness I think it will be a great move in the long run. I think water quality issues are there everywhere I mean although there may be there may not be a water availability issue in West Bengal but water quality issues are definitely there I presume so maybe something could be done in that area. Yeah and in big condominiums where there is a urban population like we are all aware of these issues so therefore that sort of rain harvesting which is not quite common in our areas can easily be done this is also an awareness which we can start at our areas and neighbourhood this is what I feel. Okay excellent thank you so much knowledge institute How is the geothermal energy is used to produce the electricity sir can you more emphasis on that? Yeah geothermal energy the reason I did not see because we have many things to cover so I had to choose what to cover what not to cover geothermal energy is great where it is available but it is not available everywhere so in India there are there are relatively fewer sites where you get geothermal energy so the overall geothermal energy potential is somewhat lower there are other places in the world where it is high so basically you have heated rocks beneath the earth surface so that heat is used to generate steam so water is forced down into that strata and heated steam is recovered from another bore and that steam is used to at high pressure and that steam is used to rotate turbines so again there are no major operational costs there is no fuel as such the earth's heat is the fuel so in that sense geothermal is a great idea and it is a very good option where there is geothermal potential thank you sir we are producing the individual home to produce the rainwater harvesting tank right to improve the implementing in our house to improve the groundwater levels okay so so you are going to harvest rainwater from the roof and then recharge it to the aquifer okay that's nice so have you planned any anything to do with your students yes sir we can produce here we have many projects sir make a product project we i am from mosconology institute in the department so our students they did one project regarding that most of the ground areas covered only by road concrete surface road and bitumen road so in that the most of the rainwater is going accumulating into the drainage that water get wasted which is combined with drainage no so our student what they did one project below the bitumen surface or concrete surface we kept one filtration bed out of that there will be voids or pores inside that through the rainwater will get the Gaussian to the filtration and then it will directly go to the ground surface and that will be increased the groundwater level of that surrounding area that is one of the project we have did and it is implemented in some in our college campus it is in process right now sir wonderful that is for road surface thank you so much for sharing it tejpur university sir yesterday you were talking about this sanitation program and you were comparing india with china and bangladesh yes and you said that for sanitation india is lagging behind yes and at the same time you were talking about water conservation yes so for sanitation sir we need lot of water yes in my opinion this is contradiction so what you feel for this yes good point i i i am a little surprised that the message didn't go through because i had i had juxtaposed these two things only to bring out this this contradiction now the the issue is if you have at at one end we require sanitation and sanitation need more water so it worsens the water crisis so that is why i said that there are alternative ways of providing a effluent treatment as well as so with watershed management if you you can make more water available and that water which has been made available can be used in an efficient way so rather than flushing down good drinking quality water in most of our cities there is only one quality of water which is which is supposed to be drinking quality water and that is what we we fill in our overhead tanks and that is what we flush down the toilet also so that that is not a very intelligent way of using water so that is why i showed you examples of grey water recycling and of even to the extreme extent of dry composting toilets so dry composting toilets do not require any water if we are in the conventional mindset where sanitation or a toilet means the kind of flush toilets that we are used to then it it leads to a problem but there are alternatives and moreover even if you are using water but that water is recycled grey water recycled grey water is is okay to flush you do not require high quality water to to flush down the toilet so alternatives are there in fact in my talk itself i have given alternatives and there are people are very innovative we just have to look around there are so many excellent examples in this country and and outside of this country that people have have come up with so we should among the various options available which are the ones that we choose and adopt the choices is in our hand so i am so glad that you pointed out this thing that contradiction was deliberately there and in fact i thought that i had brought out the contradiction but it now now it appears to me that that contradiction was not brought out effectively so i take the blame for that that i was not able to successfully communicate that sir the one thing i am i would like to ask you in this presentation one thing when when we are when i will go and see this topic of energy what will be the future for the energy because each source of energy has some pros and cons nuclear energy has some positive and advantage disadvantage hydroelectric thermal but what what will be the future what is the solution that is something is missing in this presentation which i feel that what will our vehicle happens when all the fossil fuel exhausted yeah good question let's consult an astrologer what will the future be no my my this is only one session i have the next session in which i'm going to talk about solutions thank you thank you so much