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So, this gives them an idea if the same material were heading down further and further down if this were sinking into the core then what would happen. If we were sinking below the earth’s crust if it fell through the earth’s crust and kept slowly sinking deeper and deeper inside what would happen, what in what condition will it exist. So, this is something that people need an idea for right. Then we also have information about earth’s gravity and the magnetic fields of the earth. So, again you had this. So, this is obviously, going to you know all this information has to be pulled together. So, you have a magnetic field. So, you can sort of figure out what kind of material should be there. So, we need something that will be able to generate and sustain magnetic fields being present inside the earth. So, that is how you figure out that now what kind of materials we narrowed down what kind of materials may be present. Another very important parameter or very important information that people use to figure out what is sitting where on the earth because if you can see here we have come up with nice layers right, we have so many different layers saying this layer is this material that layer is the other material etcetera how do we ever know this they mean it is impossible for you to I mean figure this out without even doing a sample. So, one major you know data point for this comes from earthquakes ok. So, that’s a very important data point in this analysis. So, what happens is every time there is an earthquake there are seismographs these are instruments that are recording the earthquake intensity they are recording the time that the earthquake took place etcetera. These are located all over the world ok. So, now, they have a presence all over the world. So, you can figure out you know based on the data picked up by all these seismographs you can sort of try to figure out what was the path that the earthquake wave took for it to reach that location. So, therefore, you can use this information collectively spread across all these places where this was recorded to figure out what sort of materials it must have gone through to have arrived here at this point with this kind of intensity or attenuation etcetera. So, that kind of analysis they do and on that basis, they figure out what might be they say you know kinds of materials that may exist in this path between here and where that earthquake took place. So, this is another very important piece of information. So, you see that all of these are sort of indirect pieces of information maybe except for the what comes from the volcanoes what is the heat present inside the earth and some experiments that we do on the surface minerals which is, so these two are direct what is on the surface, what analysis you do on the surface is direct. What analysis you do on the volcanoes is direct those two are perhaps only to direct pieces of information you have. Everything else is an experiment that you do and you make the conjecture that this is possibly what is going on etcetera. But these are all diverse experiments they are you know experiments from different, totally different starting points and so if you have a model that puts all of this together and shows you that if you had a certain composition for the earth and if that composition was distributed in a certain way in different locations on the planet different depths in the planet. Then the property that the planet would demonstrate would be consistent with all of the data that you are getting here ok. So, its density its gravitational field, everything a magnetic field, temperature, everything would become consistent if all of those parameters were right. So, this kind you know consolidated analysis is what enables you to come up with this kind of information. And even there, there is no it is not that it is without any controversy. So, for example, different models it is not I will not say controversy different models predict different values for what is the exact temperature of the core for example. So, there are models which predict about 7000 degrees C there are other models which predict about 5000 degrees C, 5500 degrees C. So, a range of temperatures are there, but at least, in general, they agree with this idea that you know you are starting at around 0 degree C and as you go deeper and deeper into the earth you are looking at several 1000 degrees centigrade increase in temperature. So, this comes into the planet from the time that the planet was formed. So, it is inherent and in internal to our planet and it exists. So, you can see here we are occupying only 30 kilometres we are not even occupying 30 kilos we are just occupying the surface of this 30 kilometres right. So, we are not occupying anything. So, we are you know the crust itself if you see is 30 by whatever 6400. So, if you remove that. So, you are looking at roughly 1 by 2, 1 by 200. So, it’s only 0.5 per cent of the thickness of the earth right. So, it just in terms of thickness 99.5 per cent is everything, but the crust ok. So, everything else is 99.5 per cent related to the crust. And we are as human beings we are using not even this 30 kilometres we forget 30 kilometres forget 20 forget 10 we are barely using the top you know I would say we are using the top 20 meters maybe top 20 meters top on average across the planet if you look at all our agricultural activity, all other activities we are probably using only the like the top 10 meters of this crust across the board. If you look at you know you know the foundation of our buildings and average it out because there will be people who will be using just the surface alone there will be people who will be digging a little deeper, if you average everything out we are probably using only about 10-20 meters of the crust. The rest of it we are not using at all. So, we are using much less than this. So, if you see even, even if you consider the crust as a whole I am saying that we are you the crust that is only 99 that’s only 0.5 per cent. So, and in reality, we are probably using. So, this is 30 kilometres. So, even if you say 30 meters. So, that would be another what is it another two or three orders of magnitude let’s say three orders of, magnitude. So, let’s just see that 30 yeah. So, you are looking at 3, 3 orders of magnitude less in terms of actual space that we use. So, we are looking at instead of 5 into 10 power minus 1 you are looking at 5 into 10 power minus 4 per cent. So, this is the actual volume that we use the actual thickness of the planet that we use 5 into 10 power minus 4 per cent is the thickness of the planet that we use. So, something like you know 99.9995 per cent is unused. So, 99.9995 per cent is unused by us of the planet. So, therefore, if there is energy in this planet that is distributed into this 99.9995 per cent of the material of the planet for all practical purposes it is infinite for us, its infinite energy that is available for us we are using such a mean we are not using it. In fact, at the moment we are not using it, it is all available there its almost infinite energy for us and we can potentially tap it indefinitely. And in foreseeable future I mean even if I mean extensively use this energy the chances that we are going to run out of this is just impossible I mean is nonexistent in any grand sense of the word. So, this is for some information that we should at least you know keep in mind as we sort of look at this activity. So, we are using a very small percentage of the crust this information this amount of material and therefore, any heat that it contains it’s a huge thermal mass right there is a massive thermal mass that is sitting under us which we can tap heat is energy and if we can tap this energy we are in excellent condition. So, the geothermal energy is essential that we are tapping the energy that is available under us and it is already there. So, you don’t have to burn anything, you don’t have to again burn coal or any such thing you simply have to reach that hot spot that is it you have to reach the hot spot and essentially ascend let’s say water get the water hot and bring it back up and then utilize it. So, this is essentially all we have to do. So, if you have some volcanic activity already something from inside is coming out ok. So, if you have some volcanic activity something from inside is coming out. So, if you get to regions that are closer to volcanic activity region so; obviously, you cannot work very close to a very unpredictable volcano and you have no idea what might happen, so a little bit away from it, closer to those fault lines where there is a chance of this volcanic activity being present you have more access. So, this crust even though I say 30 kilometres, is not uniformly 30 kilometres. So, based on where it is you may have a slightly thinner region slightly thicker regions based on non-uniformity etcetera. So, if you can access those regions you can get to higher temperatures sooner. So, that is the basic idea. So, as I said this temperature range is something that you know people have done a lot of theories on and they have got this value. So, if you see, the temperature gradient is off the order of about 25 degrees C to 30 degree C per kilometre ok, so 25 degrees C to 30 degree C per kilometre. (Refer Slide Time: 26:26) And it is a little less if you go to the northern latitudes 20 degree C per kilometre in the northern latitudes and 40 degrees C per kilometre in the closer to the equator. So, these are the kinds of temperature we are looking at we will get to this in an in just a moment. (Refer Slide Time: 26:51) I also wanted to add this information we discussed this when we spoke about even the OTEC ocean thermal energy conversion process, where I spoke about this location called the challenger deep or Mariana’s trench and that is about 11 kilometres deep. So, that is why I pointed to point out that in the crust is 30 kilometres thick, we are not even accessing most of the crust this is you know a rare occasion that somebody has even come to this depth. And deeper it is deeper than the height of Mount Everest which is about just around 9 kilometres. So, that point is deeper than the height of Mount Everest. And this itself like I said is quite difficult to get. So, interestingly if you go the other way around we spoke about an exotic situation of you know comparing this with going to space reaching the moon etcetera and discussed at how easy it is to reach the moon relative to going down 11 kilometre deep, but forget about something that exotic about going to the moon if you just go 11 kilometre about an equal to equal distance up into the air that is very accessible. So, if you took at all commercial airlines, commercial flights. So, commercial flights especially long-distance flights not short flights which are you know going from you know neighbouring cities etcetera like they will not go to that greater height because they need to again start descending. But if you take long-distance flights transatlantic flights, flights headed off from say India to Europe or something like that or India to Australia some longer distance flights they are all on average around 10 kilometres in height. So, they are all about 10 kilometres above the sea level travelling about you know 1000 kilometres an hour roughly those are the kinds of numbers we need to remember. So, at any given instant I mean there. So, there are 1000s of people who are routinely at this height right at 1000s of people are routinely travelling at this condition and any given day 10s of 1000s of people are travelling at this height any given day. So, even at any given instant right now there could easily be a few 1000 people who are 10 kilometres above the sea level at this instant. So, that is so commonly being accomplished by us human beings at this instant there are 0 people at 11 kilometres below this sea level. So, that’s the point that we just have to keep in mind about how difficult it is if you want to go down, this is in the sea ok. On the other hand in the land, we do have regions which are considerably deep not very often many times this is done for let’s say mining purposes many times they start drilling holes into the ground for mining purposes and various other purposes also they drill down. Mining could be for you know minerals they could also be you know drilling holes to reach oil-rich regions, so we will look at that, but the point is people are drilling holes. So, technology is there that’s my point right. So, it is difficult for you to do this in the sea this 11 kilometre going down in the sea which is a particular kind of you know small submarine kind of a structure which will not collapse under the 1000 atmospheres it is not so easy to do. Most military or naval submarines are not going to this depth they are much more shallow relative to this which is where they at least officially are expected to operate perhaps they can go deeper and it is not known. But generally, officially they don’t go anywhere close to this kind of depth. But in the land, you can dig kind of deep and people have done it for various reasons. So, 12 kilometres deep is known. So, we are looking at this kind of a gradient, 40 kilometres, 40 degrees centigrade per kilometre closer to the equator and 20 degrees centigrade per kilometre closer to the northern latitude. So, this is the extent to which the temperature climbs as you go deeper and deeper into the earth in the crust ok. So, we are only looking at the crust. So, if you see and that is the reason if you go back here you have a crust which is about 30 you know 30 kilometres deep and that gives you about 700-degree centigrade right. So, that’s the kind of temperature. So, you are looking at little over say around 23 degrees centigrade per kilometre. So, roughly around that will get you this 700-degree centigrade. (Refer Slide Time: 31:12) So, if you, therefore, start digging into the earth you can get these kinds of temperatures. So, common usage of the geothermal energy given that you have these 25 degrees to 30 degrees C per kilometre common usage of geothermal energy is in the 150 meters to 200 meters depth ok. So, lot of people have demonstrated at least 150 to the 200-meter depth I mean something some that you can go that deep and you can get this kind of temperature and then utilize it for some purpose, but at that point, the temperature increase is less than 10-degree centigrade ok. So, that is not that effective or that useful. So, 10-degree centigrade is not particularly great. On the other hand, if you look at say the oil industry ok. So, the oil industry again because there is a commercial activity here and there is a significant profit margin involved in this. So, if they managed to find you know an oil field at some depth and they can get do some non-destructive evaluation and they figure out that there is an oil field down there and they get an idea of the extent of the oil field let’s say they figure this out. Once they figure this out they know what is the profit margin? That is available in that oil field given that that huge oil field is there. So, they do not mind investing in a drilling process which will get them down there which may be difficult and even expensive, but overall in the grand scheme of things, it will be a small fraction of the cost. But for us more importantly what this has done the indirect benefit for I think the general environmental community is that the technology now exists to drill 5000 to 10000 meters ok. So, the technology exists people have that kind of capability to drill those kinds of holes we are going to see. A couple of examples of it where they can drill this kind of hole. So, you can see here if you are looking at 30 degrees centigrade per kilometre. So, even if you go, so if you go about 10 kilometres deep, so 30 degree C per kilometre. So, 10 kilometres deep implies about 300-degree centigrade ok. So, 300-degree centigrade is going to be the temperature 300-350 you can get some temperatures like this. So, what is the consequence of it? Typically at this kind of temperature electronics, any electronics that you put in will struggle. So, why would you put in electronics? You are sending some machinery down there which is digging you may need to control it in some way you may need to send instructions to it, it may have to make decisions based on what it is encountering there what I mean how much torque to put how to do it etcetera all those kinds of decisions might have to be made. So, there will be some electronics there which has to continue to function as the machine operates. So, many times if you are reaching about 350 degrees kind of temperature that might be an issue. So, that has to be addressed ok. So, that is an issue that we will keep in mind.
 
 
 
 
 
 
And generally, as I mentioned if you have faults that will enable access to higher temperatures, so if you have if there are you know geographical faults that are present that will enable access to higher temperatures. So, now, if you see 350 degrees C you know it is a very nice number so to speak in the sense that at that point you well past the boiling point of water right. So, you are actually, so even if you go to let’s say 4 kilometres deep at 4 kilometres deep you are already past the boiling point of water 4 kilometres depth. So, boy you would have crossed the boiling point of water. So, you can get steam at if you just cross 4 kilometres depth. And the nice thing is, this is there is no great I mean although like I said you know faults will enable you to access these higher temperatures the reality is I mean since you have this general thing that you know every 30 degrees every kilometre you will not have this 30 degrees C increase in temperature, you can do this there is no great restriction on the location there is no great restriction you can do it at other locations just the exact gradient may be different and at what depth you will get a particular temperature will be different. But in principle, you can do it and you can easily cross the temperature of the boiling point of water because water is a fluid that is easily available there is no environmental concern concerning it, it is part of our environment two-thirds of the world is the water we are you know significantly filled with water. So, water is not an issue. So, if you just send water in and you don’t even have to waste water you send the pump water in it will just go it will heat up past the boiling point and you will have steam pull the steam out, run a generator cool the steam send the condense it back to water and send it right back into the hole. So, you can keep this in some kind of a closed-loop. So, you don’t even have to wastewater. So, there is no wastage of water except some minuscule amount and you can keep this running and essentially this can run indefinitely I mean you as long as the heat is reaching that spot you can keep running it. So, this is a very environmentally extremely friendly kind of technology like some many of the other technologies we are looking at. Here there is no, I mean we are not even really looking at any kind of a polymer or any there is no chemicals involved nothing the only environmental issue perhaps is that when you drip when you dig, these deep drill holes there is a possibility that you will also release some gases which may be trapped in those areas ok. So, you may have other gases which are trapped well beneath the earth which otherwise would not have been able to come out, but because you have made a hole, you are punctured through some part of the crust and you have enabled some of those gases to escape. So, that may vary from location to location and you have to make a judgment on the relative benefit that you know you have dug some distance into the crust, you are going to get heat, you are going to get energy over such a long period, but are you know any other release that you are creating in that situation is that having any environmental impact that is over and beyond what is acceptable. So, that is the one environmental concern you have that. But beyond that this is a very nice straightforward technology you just dig a hole send water in convert it to steam, bring it out and then run the turbines. But more than that actually as we will see going ahead we may not even need to convert it to steam ok. So, as we saw that concerning you know OTEC system we are looking at temperature difference thereof only about 25-degree centigrade right. So, we have about surface temperatures in their 25-30 degrees centigrade and then you have water there at the floor of the ocean or 1 kilometre below the surface which is at about you know 3 degrees centigrade or something. So, even with a difference of about 20 degrees centigrade in the temperature you can run the plant and you can run the plant and you have a closed-loop version of running the plant, you have an open-loop version of running the plant, we can you know you can put low pressure run it in the closed-in an in an open-loop kind of a situation where the water is being released or you can have a different working fluid which would then be a lower boiling point material, in that case, it was ammonia and you could use that to run the turbine where you would take the warm water and create this evaporator you take the cold water and you do the condenser. So, you have those options available even at a temperature difference of 25-degree centigrade and we as we saw here that you can get 25-degree centigrade in the ground by just going 1, 1 kilometre deep right. So, therefore, what we have learned from OTEC is the fact that you don’t even need to go to you know 100 degrees C, 200 degrees C, 300 degrees C etcetera even without that you can actually run this and still run get some energy. But clearly, if it is the higher the temperature your efficiencies are going to be much better and with a single plant, you can do much more, therefore, if at all you are going to sink a hole in the ground to set up a geothermal plant it makes sense to see if your technology will permit you to go deep enough that you have a high enough temperature that you know the efficiencies are strong I mean very high and therefore, you can you know to serve a significantly higher energy demand. So, that is, therefore, of interest, we saw that even 10 kilometres deep would get you 300 degree C which is very significant. So, your efficiency would go up dramatically if you instead of 30 degrees C a difference you went to a 300 degree C difference right. So, this is something that we will keep in mind. (Refer Slide Time: 39:39) So, just for example, just to give you an idea of I mentioned that you know the oil industry already does this relatively successfully, just to give you some idea. These are two different oil platforms. So, these are actually in the sea deep-sea deepwater horizon was one of them and Sakhalin is another one this is the second one is somewhere is controlled by Russia the first one is in the US, and they have gone 10 and a half kilometres deep. So, this is out in the ocean then they hit the floor of the, so of the ocean and then they continue digging deeper ok. So, they continue digging deeper and therefore, they have gone that far deep into the ocean and in this case, for example, they have gone 12.3 kilometres deep into the ocean to reach into through the crust they have dug deep in through the crust and reach that point. So, therefore, that’s that that was the point I wish to make that the oil industry has this technology to get to this kind of depth. So, therefore, it is not dramatically different for us to do. It is actually in some ways easier for us because if you are talking of geothermal energy because when we set trying to set up a geothermal plant we are not actually, not prospecting for oil. So, we are not particularly concerned about you to know we have going to dig this deep are we going to find oil we are not interested. We are not interested in finding oil we just want you it’s absolutely fine to go to a location whether is no oil and dig a hole this deep. So, that’s acceptable to us and therefore, in fact, we would perhaps prefer not to have some pressurized liquid or water in there or any other thing in there because it might come gushing out and it may damage everything that we have. So in fact, I am if you go and look up in the in any online search you please search for deepwater horizon this was a huge environmental disaster in the united states where they had set up a big oil platform which went this far deep into the underground to reach an oil you know oil field. And then just as they got the whole process started and running it was fairly recent 2010 if you go and take a look at it, as the oil came out they lost control of that process and it just blew up many of their you know control systems that were there in the pipeline and then the oil rig itself caught fire. It caught fire several people died in that accident it was a very you know severe and you know devastating accident, they died the entire oil rig collapsed and it sank into the sea. There were several you know I think more than 100 people were there in the place when this accident happened most people were evacuated, but some people were they couldn’t evacuate and they died. And the accident itself was bad in terms of you know the fatalities and you know the damage it had done to all those families and so on, but more than that I mean or at least you know that being one part the other major part was that there was a huge oil leak. They had already drilled a hole to reach one oil field and they had lost control of that hole there is they have to keep proper control on it. So, that they get this out in a controlled manner they lost control of it and so this oil began spilling out. So, it cost one of the worst oil spill disasters in history it is you know the massive amount of oil that got spilt and it took several weeks, several weeks before they could. In fact, in the order of months before they could find a way to plug that hole they struggled. So, hard to plug that hole to stop that they tried various things they kept on if you read the history of this event incident you will find that they tried several things to try stopping that leak they couldn’t they struggled. So, and only then they could you know manage it after several months. So, it is a complicated thing. But the point is you know far from our perspective if you are looking for geothermal energy this is not an issue, we are not looking for something underground we want to make a hole to just access the temperature that is there and therefore, this is very clean energy. And so not only we avoid you know the burning of fuel which was taken up by that hole if it were an oil drill. We do not even have the problem of a leak from an oil drill because there is no oil there and therefore, this is not an issue for us. So, you can go look this up there is a lot of information on it, there is I think this is even a movie based on it called a deepwater horizon. So, you can take a look at. As I said that is not the end of it this is Exxon is a big company. So, they have also actually worked I think in Russia and they have got a hole that is 12.3 kilometres deep. So, this is routinely being done by the I may not be routine, but at least the capability is there to make these kinds of holes and the nice thing is there is it is not a finite quantity that is there you get there, you get that temperature and you can keep working on it. (Refer Slide Time: 44:27) Generally, the anticipated lifetime for geothermal energy usage is about 30 years. This is again you know some estimate that is there based on you know how much heat is arriving at that location and how much heat we are extracting. So, this is not that the place becomes unusable after 30 years it may temporarily not be as effectively usable. But it depends a lot on you know the thermal moment, so the moment of heat from well within the earth to that location. So, that is got a lot of thermal mass. So, you as we saw you know 99.99995 per cent of the land is below that. So, if you are 99.5 at least is below that of the planet. So, that much thermal mass is there at a much higher temperature. So, you are not going to run out of heat that easily. But this is the expectation is that if you use a spot for about 30 years it may be that locally it may cool a little bit if you give it some time it will recover and then you can continue using it. So, this is one thing. But even in even economically perhaps that gives you some idea of how long this unit can be used. So, this is the kind of you know an energy phenomenon and you know the kind of concept that is involved in geothermal energy and as I said here if you go back to what we looked at in terms of temperature you have this huge temperature range. So, all of this we are not going to be able to access, this is much much deeper we believe it is there, but we cannot access it. So, we are looking at this 0 to 700 degree C temperature and there also we may not go the whole 30 kilometres because we also do not want to you know to create a situation where we have punctured through and we are having you know leaking lava coming out of that location. So, it is more than adequate for us to do anything of the order of 5 kilometres to roughly 10 kilometres.