 Hello, welcome, welcome everyone. So we will be going through our last module, the module number 4 for this particular topic of hydrogen energy from biomass and the coal. In the past 3 modules we have looked into the biomass, different technologies like pyrolysis and the gasification process, how to get the maximize the hydrogen yield through that using hydrogen in the biomass as well as in the through the steam as a reactant which reacts with carbon. So using carbon in the biomass as well as the hydrogen present in the biomass to give you hydrogen. Now we will discuss about the coal. So when we look into the coal first we have to identify or understand the fact that the coal is coming from your biomass. So biomass is what has given us the coal. So if you look into the time as we all know that there was a era called carboniferous period which is actually attributed to bulk of the coal that we have now. And the reason being there is a very interesting story about that. Is that coal that has come through all the era or whatever plants are today what we have, will it give us the coal after millions of years to the future generation. So this is a very interesting story and I have given these two links. I would request all of you to go through these two links. It is a very interesting story, a very interesting story that it was the lignin, it is the lignin which has given us the majority of the coal that we have. So in the early era of the evolution most of the plants, well it is not most of the plant but all the life evolved initially into the under the sea. Then from the sea it came to the ground. But in the sea there was a unique thing that even if the plant grows tall like this tree, if it grows tall there will be a buoyancy force of the water that will keep it floated. It will not fall under its own weight. But when the plants start growing on the land then the issue of how the tall trees can support itself. So there was a million of years, millions of years the plant did not have this compound called lignin. So and this is what you see the shrubs, the grasses and all which are very light in weight which will grow if they grow tall they will just bend down and will reach to a particular height on it. But to compete especially in the thick forest to compete with the sunlight you have to grow tall and that is how the evolution happened. But after millions of years the evolution gave this magic chemical that is a lignin. So this organic compound that is giving the strength, strength and the structural stability. Structural stability to the plants and the trees. So even it will grow it will not bend under tree and even for the smaller plants or the shrubs it gives the structural stability to withstand the heavy wind or the animals or any impact as such. So this lignin become a very universal for most of the big plants and trees and all. But there was a problem that still no microbes to decompose and that issue is still there but not 100% just to give you a perspective. All of you would have noticed just imagine a coconut shell or a big tree trunk somewhere lying in the open. If you have dry leaves, dry leaves or fruit and all if you see it in the open it will be just few days, a week or a month and it will completely get decomposed or some insect will come and eat it or microbes will decompose it completely to the sort of powder. But a coconut shell if you keep throw it in the open you come back next year the coconut shell still it will be there. You come after 2 years you may still see it there. You will not see any animal which will eat it because they do not digest you cannot digest the coconut shell it is very high in lignin. Very high in lignin we do not have enzymes which can digest the lignin thing. Same thing is with the microbes majority of the microbes do not have any enzyme which can digest or decompose this lignin thing. So it went again millions of years because evolution process is slow. It took again a million of years until fungus which was found or which was evolved which could digest which could attack lignin and can digest it and decompose it. But this fungus came millions of years later and now right now also you can imagine if you are in dry presses this fungus which needs high humidity to grow you will not see this but if you are in a very wet area or during the monsoon then only you will see the fungus grows and it grows every anywhere even on your wooden table in a wooden shelf it will grow because it can eat lignin it can digest it it can survive on that and most of the mushroom it grows on the tree trunk. So these are some of the evolution process which took some millions of years and that millions of years is called the carboniferous period and in this carboniferous period when the trees after their life they were dying out every tree will have its own life every plant will have its own life. Most of the other body parts accept the lignin part accept the trunk the branches everything will get decomposed by microbes animals insects they will eat it up but this lignin based trunk the branches they still remained unconverted and they just piled up over the in the jungle and it was not few years but millions of years it was million of years where it has covered the jungles in the forest in the with the pile of lignin and then through earthquake or through flood or through something it undergoes the under the ground and then under the ground within the thousand years it will decompose slowly but this is thermal decomposition now. So in the lignin lignin if you give heat it can undergo pyrolysis a decomposition will happen but there also lignin is much more stable compared to cellulose, hemisolose which also makes a bulk of your plant. So this peat and then further heat and pressure high amount of pressure so it has heat plus pressure that is moves more under the ground more under the ground high amount of pressure high amount of heat it converted it to lignite and the coal finally. So these are typically many people they identify in some literature you will still find this lignite and peat classified a different category of coal but we do not need to go under that thing but the thing is quality of the coal varies and how is the quality of the coal is varying is if we look into the fresh biomass fresh biomass which will have around 55 to 65 grams of hydrogen per gauge of biomass it has around 50% of oxygen in its molecular form all organic molecules will have 50% of oxygen by weight by weight and roughly around 40% of carbon by weight and little bit amount of hydrogen and some other inorganics like iron sodium chlorine and all it will be there potassium and all it has a calorific value of around 14 to 17 mega joule per kg. Now when we look into the peat which has come after that it stayed inside the earth crust for around 10 to 15,000 years it is a long period but still you have some 60% of organic matter still left so that is the you can see how slow the process was and how the slow the process is of the coal formation from the biomass. So still after 10 to 15,000 years 60% organic mass is there there is a very small increment in the calorific value then after 6 crores years or 60 million years after 60 million years what you get is a lignite which now has high amount of carbon and lot of oxygen has gone out as a moisture because it will be oxygen will be embedded in that the dry carbon and the coal will have or the dry coal will have less amount of oxygen in it the calorific value also almost doubles if you look into 14 to 17 mega joule in biomass and you have almost double the calorific value now then again few more crore of years or more than 100 to 300 million years now what you have got the carbon content has now increased to 60 to 80%. The decomposition is happening hydrogen and oxygen is leaving the system hydrogen and oxygen is leaving the system now you have no organic molecules left but just see the timescale 10 to 30 crore years 100 to 300 million years that has been the timescale when the trace of the organic compound has left still and the calorific value also improves in that and the anthracite which is like one of the best quality of the coal that you will get around 35 crore or 350 million years old which has 80 to 95% of coal negligible amount of moisture very high calorific value of this thing but hydrogen content is very very low only around 20 grams hydrogen per kg of per kg of coal. Yeah so hydrogen content is very low around 20 gram per kg of coal only so that is the overall evolution of your coal from the biomass so that is why I kept these two together now we understand what the biomass and how much is the biomass having hydrogen and then through the this long duration of period and under the intense temperature and pressure inside the earth crust then your biomass has converted to your coal of different categories under the different timeline of the period and every type of coal will have different content of your hydrogen but anthracite or butuminous will have very less amount of hydrogen in it. Now this is some of the figures that is the first heat decay of the vegetative material second stage is the lignite third stage the butuminous coal this you can see like a blackish which looks like coal and anthracite coal considered by some type of metamorphic rock. So in the literature we will see the different definition of this coal but this is more having high amount of carbon in it hydrogen is very very low in it most of the hydrogen has been lost during the coal formation. So now looking into the coal gasification so this gasification overall chemistry is similar to what we have seen in the biomass gasification process. It is the early 19th century technology coal gas was used to light up the streets in many European cities so that is coal gas and this is nothing but your carbon monoxide plus hydrogen so this was used to light up streets that was a street light system in the 19th century so you can just imagine how old and what could have been the gas which is carrying carbon monoxide in it is used for the street lighting interesting isn't it. Now looking into the quality of the product gas depends on the quality of the coal used if the coal has high amount of hydrogen it will have a little higher amount of hydrogen even though coal gasification it is the inherently the steam gasification steam gasification but if the coal also is of poor quality it will have high hydrogen it will have high amount of hydrogen compared to high quality high grade coal will have less amount of hydrogen in your gas or the synthetic gas. So steam gasification and two stage gasification plus shift reaction is used to enhance the hydrogen yield. So this is the hydrogen yield again the shift reactor that we have seen the reaction of carbon monoxide plus H2O that gives you H2 plus CO2 so to enhance the and this is the second stage or the what we say the catalytic conversion state never which is used for the coal gasification process for hydrogen yield. Now hydrogen production through coal gasification so coal is gasified first followed by the products gas passed through catalytic shift reactor with steam supply partial oxygen supply helps in exothermic oxidation and hence sustaining the overall process. So this is similar in the biomass gasification we have seen it is the volatile which was the gas reacting with oxygen and the exothermic reactions of volatile combustion was sustaining the endothermic reduction as well as endothermic paralysis and the drying process. But here the solid fuel that is the carbon itself is undergoing oxidation yeah the reaction will rates will be slow but if the temperature is maintained high if you design a reactor in such a way reduce the size of the coal particles to very small you can get a very high reaction rates here as well and that is what is done typically the pulverized coal is what is used in the coal gasification systems. Very small micron size of coal particles are used which enhances the surface area and that is how it enhances the oxidation process of the coal for this exothermic reaction which has sustained the overall process. So again the same Boardward process which is endothermic C plus CO2 and the water gas shift reaction CO plus H2 which gives which is also mildly exothermic process which is prominently sort of present here. We are not looking into hydrogen based reaction because hydrogen is not much into the system as such. So this system and then this carbon monoxide can be used through shift reaction to enhance the oxidation hydrogen content and this is the carbon monoxide which can be used for further second stage with the separate shift reactor where we can have the hydrogen plus CO2 giving you high amount of hydrogen plus CO2 and then to get the more amount of hydrogen through it. So this is the simple chemistry unlike biomass gasification reactor here the shift reaction is preferred to be in the separate second stage as such. Now looking into the coal gasification process. So coal gasification process is one of the higher amount of hydrogen around 25 to 30 percent 30 percent of hydrogen global hydrogen is coming through coal gasification and you can imagine there is a huge demand and then there is a huge requirement of big plants and all. This is one of the very simple means not very simple complex but very economical design. You use the underground or the earth itself as a side for the supporting the reactor. So here you can see this is your earth inside it they have dig up the reactor part and they had made the reactor inside the coal is supplied from here you have a oxygen separation plant oxygen is separated from the air and is supplied here and then you get the gas from it and you sustain the overall process overall the very big reactor you can make it inside the earth itself. So this is the very popular coal gasification system and is pulverized. So the typically the coal particle size is of the 5200 micron and typically the reactor type is pulverized coal in entrained flow or fluidized bed reactor. So these are not referred much into the fixed bed reactor like the earlier gasification that example that we have seen the figure that was the fixed bed packed bed reactor where bigger size of the biomass was used but here the smaller very fine size of particles are used because you have to enhance the solid gas reaction and that can be enhanced by increasing the surface area of the coal particles and that is done by pulverizing it pulverized coal and the entrained flow or the fluidized bed reactors are preferred here. So in the hydrogen production system what you have is you have a crushed coal that is pulverization happens here you put in the micron level size and the ash comes out the solid whatever the gas comes out you remove the particulate matter that is still some dust some ash will be flowing with it the solid particles you remove here then you have a special requirement of sulphur removal. And typically in biomass most of the biomass you will not have much of a sulphur that is problematic enough to remove it but in the coal the sulphur content is significantly high and this needs to be removed before you push it into the hydrogen separator because those reactor and also this water gas shift reactor the catalyst use gets poisoned because of the sulphur present. So that is how you need to remove the sulphur so there is a sulphur removal unit and after that you remove the CO2 and H2O H2O easily gets removed by reducing the temperature below 100 degrees by condensation CO2 is removed typically by I mean solution or by high pressure water spray and then this particular carbon monoxide or hydrogen you can use for different chemical or the fuels like we have talked about for example the F T synthesis F T synthesis which will give you petrol or diesel. But if you are looking for hydrogen then you have to go through a second stage reactor that is a water gas shift reactor because it is the catalytic reactor for high sort of amount of hydrogen to be produced it cannot be clubbed here where there will be lot of sulphur present in this particular reactor it would not be there we need to remove the sulphur first and then feed it into the shift reactor and then by enhancing the hydrogen we get more hydrogen. So this figure is talking about the fuel cell but we can use the hydrogen for any purpose after separating it from the system. So this is how the thing is there one of the very interesting sort of philosophy or the new thing that is getting prominence in research in India as well as the underground coal gasification. So let me just spend few minutes here quite an interesting thing this not again new technology Russians have mastered almost 50 60 years back. So what exactly it is you like we have seen here in this particular reactor you design a reactor you design a reactor underground but in the underground coal gasification what you are doing you are using the mine itself as a reactor here what we have done is we have mined the coal and supplied here this is coming from the mines we supply it here we pulverize it we do the processing transport everything we do and then we push it into the reactor we are just saving on the cost of the construction of the reactor but here what philosophy is once you start getting this coal out of the cavities you still have empty cavities in it empty cavities why not use this cavity itself as a reactor. So these cavities are itself of the coal which has high surface area because these are huge mines all the surface exposed will be will be able to give you a reaction site. So all these things are here and in this cavity what you are doing is you have an injection well you through injection well you push high temperature steam and then high temperature steam as well as some amount of oxygen and then you push into this cavity here it will react and it will give you in the production well you extract it up where you get carbon monoxide and hydrogen from the system and then after that you do the gas cleaning because of the reactor everything you have got the gas cleaning then pass it through sulfur removal then water gas shift reactor enhance the hydrogen content through it whatever you want to do it but the overall reactor is underground. So this whole huge cavities it will not be just bit like a building it will be kilometers long so these are the sort of a huge reaction sites that you can enhance once you can have a control over it but yeah it is not as easy as it looks because with the reaction and all this some of the was it start collapsing start collapsing and you need to have a control over that Russians master it long back but it is not a open technology from that still I think 1 or 2 underground coal gasification mines are still operational in old part of Russia I think before the USSR it was it is in I think Kazakhstan or Uzbekistan but right now China is also investing a lot in this particular technology and here this carbon monoxide and hydrogen you can put it through and put up a methanol plant put up a methanol plant from it methanol the major feedstock is carbon monoxide and hydrogen and then you can get methanol through catalytic conversion process so they are doing the carbon coal to methanol projects China is doing that and then India is also looking for that the reason being reserve of coal and the energy independence so you do not know you never know like even in the current time or maybe couple of months back you have seen the Russian Ukraine conflict you never know when the energy supply through natural gas or the petroleum will get interrupted every country every sovereign country looks into energy independence so that we have enough of all type of energy requirement we can fulfill at our own so here in India we have a huge coal reserve but our coal one of the problem is our coal is not a very good quality for the use in steel industry or the thermal power plant because of this the thermal power plant it is used but the quality is bad it has a very high amount of ash it cannot be used for steel production and all which requires a high quality high percentage of carbon in it so but these are very good for your gasification process and gasification process once you master underground coal gasification a huge big plant running continuously for the years at a very low operational cost can give you a upper hand upper hand over getting the synthesis synthetic gas or the sin gas then you can convert it to liquid fuels methanol liquid fuels get hydrogen out of it and use that hydrogen so energy independence in one of the things and underground coal gasification a cost effective cost effective gasification process can be one of the key for it so with this I just like to conclude this overall module and I hope all of you have understood and appreciated the role of biomass and coal for the hydrogen production the different process and the chemistry behind it and yeah just with the thought there is no better way to sequester carbon than preserving nature even if we are using biomass let us use the agriculture waste or the municipal waste whatever the carbon is coming through the waste let us react with steam and produce hydrogen from it with that note I would like to thank thank for taking up this course and going through this set of lectures thank you