 In the last few classes, we have seen the detailed process of steam methane reforming, the various steps involved and we have seen that steam methane reforming it is highly endothermic reaction, wherein the heat which is required for the reaction is supplied by means of burning the combustion of the methane natural gas which is also acting as a fuel in the various burners. And combustion of that natural gas results into the temperature, high temperature which is required for the steam methane reforming reaction. Now, this burning up of natural gas results into emissions and that emissions are released into the environment. Now, if that particular part of the emissions can be taken care of by providing the required heat of the reaction by means of a renewable source, then we can reduce the associated emissions in the process. So, if the energy which is required for the reforming that can be provided by means of any alternate source like nuclear energy or solar energy or by means of electrical energy, in that case the emissions at the point of supplying the energy could be reduced in the process. Now, let us begin with looking at the nuclear assisted methane reforming, where the endothermic energy for the reforming it is coming from nuclear energy. Now, if we compare these with the conventional SMR, then there are problems associated with the integration, the reason being the operational conditions of a nuclear reactor are not that flexible to integrate with the steam methane reforming. And there are many conditions that we need to consider, there are many criteria for selecting which particular nuclear reactor is going to provide the required energy that depends upon the safety considerations, what are the operational issues in integration, capital cost involved, the compatibility with the reformer, so these are the parameters that needs to be considered. However, conceptually it is identified that all the hydrogen production methods whether it is reforming or partial oxidation or ATR, autothermal reforming or dry reforming they or the other methane decomposition process, they can be integrated with the various nuclear reactors to provide the required heat for the process. It can also be coupled with electrolyzers providing the electrical energy input. Now, what it depends upon is in the reforming specifically, what is the temperature of the reactor coolant, in the maximum temperature of the coolant that determines which nuclear concept we can use for the production of hydrogen. Like if it is a light water reactor, high temperature cannot be achieved. In that case, the required energy could be either electricity could be provided and that could be used for the energy input in the electrolysis producing hydrogen. When it is an alkali matter cooled reactor, this is in fact appropriate for low temperature usage. As such there are risk associated when we are using at high temperature chemical reactions. For heavy metal cooled or molten metal cooled, it could be promising but at present significant development is required for integration. Gas cooled reactors these are best suited where helium is coolant and that helium cooled reactors could be easily integrated with the hydrogen production method. It could be liquid core reactor there or the gas core reactor but then there are certain challenges associated and they are not recommended for use for this particular application. If we use the nuclear energy for the methane reforming, all the energy input in fact the input energy for the reforming reaction including the purification steam generation can all be met using a high temperature gas cooled reactor. And high temperature gas cooled reactor helium which is used as a coolant that can be used for indirectly providing the heat of the reaction for the reforming. And the other processes in the hydrogen production. And this can be provided the required heat can be provided using a counter current type of heat exchangers helical coil type of heat exchanger passing through the catalyst bed having feed gas. And the temperature of the helium coolant that lies between 700 to 950 degree centigrade and a pressure of 4 megapascal and that can provide the heat of the reaction for the steam methane reforming. And in this process since SMR is an endothermic process the temperature after the reforming it drops from 950 to 600 degree centigrade. Then such reactors they are integrated with SMR process then the efficiency which in a conventional SMR reformer it is 74% max it can increase to 85%. And besides reforming they are also preferred for electrolysis for integration for electrolysis or with the thermochemical cycles for hydrogen production. And not only the required energy can be fed by means of nuclear energy input but the solar assisted methane reforming can also be carried out. Here in since the reaction is highly endothermic so concentrated solar thermal energy would be required for performing the methane reforming. Now there are we know that there are 4 different technologies which could be used either a parabolic trough collector or a linear terminal reflector or a parabolic dish type concentrator or a tower with central receiver. Out of these 4 the first 2 parabolic trough and linear terminal reflectors they provide a sort of moderate solar concentration ratio and very high temperatures which were favorable for steam methane reforming could not be achieved. So as such the last 2 technologies mentioned the parabolic dish tower and the tower with central receiver these are in fact preferred for reforming integration with the reformer. Now when such systems are to be integrated with a reformer there can be either a open loop system or it could be a closed loop type of system. What do we mean by an open loop system? In an open loop system when a concentrated solar radiation it falls onto a steam methane reformer, sin gas is being produced, the temperature required temperature is supplied by the thermal energy and the sin gas which is being produced can be used for in the gas turbine, it can be stored, it can be used for various industrial processes, it can be used in a combined cycle gas turbine plant and in this whole process not only upgradation of the hydrocarbon occurs but at the same time sin gas storage can also provide a means for storing the thermal energy and then it can be utilized in a more effective and efficient manner. In a closed loop type of system through SMR the sin gas which is being produced can be stored, it can be transported over certain distances and then when it is required then it can again be converted into methane. So initially the methane is converted into sin gas and that sin gas can again undergo methaneation process to convert it into methane and then it can be used for various processes whether it is process heat generation or power generation in a gas turbine or it can be even stored for longer duration. So thermal energy when it is converted into chemical energy and in this form and then it can be stored over a longer duration of time. That thermal energy which is being produced, the thermal energy which is being converted into chemical energy can also be transported in this mode and then later on whenever it is required can be either used to convert again back into methane and in a gas turbine either in a gas turbine or it can be integrated with a steam power plant or it can be used for high grade process heat. So this is a closed loop wherein we started with methane converted into sin gas again converted into methane and used for various applications. Now how the solar heat integration with the reformer will take place that can be by means of solar receivers which can be either directly or indirectly heating the reformer to get the required heat. Now this depends upon whether the solar heat transfer to the working fluid or the heat transfer fluid occurs directly or indirectly in the process. The indirectly heated receivers here in the heat transfer to the working fluid that does not take place exactly on the surface which is exposed to the incoming solar radiation. That means it falls on another surface, the solar radiation after being concentrated they falls on to another surface. This is a opaque wall across this the heat is being conducted from the outer wall to the inner wall and from there it is being taken away by the working fluid or the heat transfer fluid such that the feed gas in this case reforming the methane and steam when they react under these reaction condition high temperature condition they produce the product gas which is sin gas. Another method of indirectly heating is wherein again after concentration the heat is it is not being the heat transfer fluid is being carried to a different place through a and they will through a heat exchanger that amount of heat is being transferred into a catalytic bed wherein or a reformer wherein the reaction takes place. So, the point where the heat is being absorbed and the utilization for the reaction chemical reaction is not the same. So, this method can also be called as LO term. A third method wherein again there is a catalytic bed but it is not directly being heated it is again indirect heating and opaque wall from where the heat transfer takes place to the catalytic bed and the feed gas being fed finally forms the product gas. Now, these mediums can be which are heating the which are providing the working fluid can be either in the form of air it could be a molten metal it could be a molten salt. So, these working fluids can be used for heat exchange it is also possible to directly heat the reformer. So, directly irradiated receivers are there wherein there are stationary absorbers which absorb the radiations directly and this category of receivers are known as volumetric type of receivers. So, the there is an absorber matrix which absorbs the heat solar radiations and then they transfer to the working gas. So, this is a direct means of heating but the these absorbers needs to sustain the thermal stresses of repeated cycling of heating and cooling and they should be thermally stable and structurally stable under those operating conditions. When the radiation is being absorbed by the materials it is these absorber materials and these are transferred to the gaseous heat transfer medium then it is a direct type of transfer heat transfer. And in using this particular method since it is a direct type of heat in heat flow. So, high heat flux can be achieved in the process even higher temperatures and better efficiencies can be achieved as compared to the indirectly heating. Now these absorbers various configurations various materials can be used for absorber and these are being directly getting solar radiations. These can be either steel or ceramic wire meshes these could be ceramic foams or multi-channel honeycomb type of structures. A significant amount of work has been carried out on solar based reforming like the some of the examples quoted here like the indirectly heated reactors where in air if it is used as a medium then the projects like Spanish-German project wherein they have used this allotherm heating concept and have derived a solar tower that they produced. So, solar driven tower that produced hot air which was at 1000 degree centigrade and 9 bar and that supplied the required heat to the packed bed reformer. Now the reformer in various instances it could be either a fluidized bed or it can be a packed bed type of reformer. So, in this case like it is a packed bed reformer wherein they observed that a conversion of 68% to 93% could be achieved. Now this is a wide range and that depends upon what is the temperature which is achieved at the reformer and this was demonstrated as early as 1990. Weisman Institute of Science there they had a central receiver and they converted that into sin gas in a reformer they stored it they transported that converting the energy solar energy into sin gas and then they stored it they transported it over a distance. And this was again demonstration in between 93 to 98 so there were several such projects being undertaken at Weisman Institute. Australia it is well placed in terms of renewables so CSIRO Australia they developed a 25 kilowatts single coil reformer S score and 500 kilowatts single tower heliostat based reforming they have undertaken and could get a temperature of 700 to 800 degrees centigrade and 5 to 10 bar pressure. Thereafter they have undertaken several such projects another project was a hexagonal dual core reformer that was of 200 kilowatt and that was being executed in 2009. Among the indirectly heated reactors the various molten metals and molten salts have also been considered for heating or as a working fluid the Sandia National Lab along with Weisman Institute of Science they considered like a sodium reflux reformer where sodium vapors were considered so its evaporation and condensation by that they have taken that amount of heat. So this was a 20 kilowatt sodium reflux reformer and this was used for performing dry reforming of methane and this was done as early as 1983 to 84. Potassium carbonate and sodium carbonate for dry reforming of methane at 710 degrees centigrade was used in a furnace that was an IR furnace at Japan and they named that system as direct contact bubble reactor. Among the other indirectly heated reactors was wherein the solid particles were used so at NREL concentrated solar radiation on a graphite tube was used and that raised the temperature to very high temperature. So the operational temperatures was about 1700 K here and for methane decomposition and they could also carry out the non-catalytic dry reforming under those conditions. With the directly heated reactors various catalysts like rhodium on alumina with honeycomb type of these structures and having a sapphire window for allowing the direct radiations falling on to the catalyst and later on they upgraded it to a silica belgium type of reactor they used it for dry reforming of methane and could achieve 67% of conversion in this process. In another reactor demonstration at DLR Germany and along with Sandia National Vab US reactors which were based on ceramic foams were demonstrated in a volumetric receiver type of reactor they had a quartz window and used catalyst rhodium on alumina. At Weisman Institute of Science Israel they used silicon carbide foam with domed type of cavity configuration and could achieve very high conversions of methane 84 to 88%. Similarly like Solace's project which was jointly being carried out by DLR Germany Weisman Institute and Ormatt Limited they performed solar reforming of LPG and then they used that syn gas which was produced in a gas turbine. And same at the Weisman Institute they came up with a new concept porcupine type of concept. So this was the different design that they came up with and they performed the reforming with rhodium alumina catalyst and a conical quartz type of window was used. So there were several demonstrations which were carried out and these demonstrations they have shown that the method of solar assisted reforming can be deployed at a larger scale it is cost effective and we can get high efficiencies. So the directly heated type of volumetric receivers they have the advantage of having getting higher temperatures, better performance and better heat transfer. While the indirect heated type of reactors they have they are comparatively less efficient heat in terms of heat transfer and the maximum operating temperature that could be achieved is also lower. So a commercial scale development is required for the sustainable use of the solar assisted reforming and to reduce the emissions. Now another way of providing the required energy for the steam reforming is using plasma. So plasma we know that it is the fourth state of matter and it consists of various ionized species, radicals, neutral atoms, neutral molecules, atoms and electrons. And this is created by applying electric field. Once we apply a potential difference a high electric field then the gas which was non-conductive in the beginning that electrons are either taken up or these are freed providing the energy which is higher than the binding energy of these electrons producing ions and electrons. Now these electrons they gain energy and they while they undergo several collisions elastic and inelastic collisions producing more ions, radicals and electrons in the entire process. In this way our discharge is created and that discharge effect it will depend on several things like what is the gas characteristic, what is the electrode arrangement and on the applied voltage. So the plasma which is produced that produces not only the required temperature for the reforming in our case but it also provides several free radicals and ions that can also be used for the reforming process. Now not only reforming various other hydrogen production methods can used the method of plasma reforming like partial oxidation or autothermal reforming. This plasma which is generated depending upon whether the temperature of the electrons and heavy particles other than electrons, ions, radicals, neutral molecules these are called heavy particles because they are higher in mass compared to the electrons. Whether all of them they are having the same temperature then it is an equilibrium plasma or a hot plasma or a thermal plasma. If they are at a different temperature electrons are at a higher temperature compared to the other species then it is known as non-equilibrium plasma also called cold or non-thermal plasma. Now thermal plasma these are actually created at very high pressures and by applying a higher potential by applying a higher power and that power could be provided by means of either a DC source or a AC source or an RF source and temperatures that could be achieved in a thermal plasma are high about 2000 to 2000 Kelvin. We could achieve very high energy density and these could be created by means of either an arc or a plasma torch or an inductively coupled RF discharge. While the non-thermal plasma these are comparatively created at a lower pressure temperatures which are achieved are lower. The temperature since it is a non-thermal plasma non-equilibrium plasma the temperature of electrons and heavy particles is different. So the temperature of electrons is higher than that of the heavy particles. The power required for creating non-thermal plasma is lower. They have a lower energy density where there are various examples depending upon what is the electrode geometry configuration. These can be either glow discharge type gliding arc type. So if the electrodes they are separated oppositely and then they have a varying gap. So the arc starts from the shortest distance and then it moves towards the largest distance and it dies down and then again another starts. So this is a sort of gliding arc type of plasma or it could be dielectric barrier where in between the two electrodes there is a layer of dielectric. This can be on one of the electrodes. So dielectric barrier type of discharge or it could be a corona discharge wherein one of the electrode is a sharp electrode and another one is a either it could be a cylindrical surface and a pointed tip or it could be a pointed a sharp electrode and another electrode could be a planar electrode. So it is it could be a corona discharge. So the discharge moves like a corona as such the name came or it could be a pulse discharge wherein short pulses of high power are injected and all these type of plasma could be used for reducing hydrogen. But the with the non-thermal plasma since the temperature which could be achieved are lower the energy densities are lower the high heavy particles have a low temperature which is close to ambient on the electrons they are at a higher energy and higher temperature and they undergo the they they perform the reaction. So as such the conditions are such that a catalyst is required so as to induce the reaction so as to excite or to so as to provide the required activation energy to the inert reactants of the reforming for hydrogen production and the temperature in case of non-thermal plasma it lies in the range of 600 to 1000 Kelvin. So if you look at the non-thermal plasma these are like the low pressure low temperature and a catalyst for is always required with non-thermal plasma so that the temperature of the reaction could be achieved which can be reduced with the help of catalyst. But the presence of catalyst can also cause a change in the pathway of the reaction because the active species which will be created they all get absorbed onto the catalyst surface and with the catalyst presence of catalyst it can change even the discharge characteristics like the ionization and dissociation characteristics can get improved and the actual chemical reactions that will take place will be by means of the energetic electrons. Since as we have seen in the gliding arc plasma there is a non-uniform discharge which is created and that is also in a restricted region of the plasmatron. So that in fact limits the conversion process in the plasmary forming non-thermal based plasmary forming. As such the complete conversion or breaking up of CH bond is difficult and that also depends upon what is the electron energy involved. Like in spite of complete breaking up of the CH bond it can even lead to formation of lower hydrocarbons and that depends upon electron energy. For example if the electron energy as comparatively higher then hydrogen could be removed such that it can lead to even formation of acetylene. However if there are lower energy involved then even that hydrogen could not be removed and then it can even result into formation of ethane. Certain amount of energy also goes in heating up the catalyst bed in the non-thermal plasma. While in case of thermal plasma since the temperature involved in the process are high the energy densities are high that can provide the sufficient energy for breaking up of CH bond. As such in the thermal plasma reforming we can get solid carbon and hydrogen as the product. So the method of thermal plasma reforming that offers higher capacity, higher energy conversion efficiencies they have we can get high energy densities and the chemical active species can result into better conversions of methane to produce the desired product which is hydrogen. So it has been observed that the conversions of methane could be which could be achieved are as high as 98% using DC arc plasma. So the plasmatron on thermal plasma since they operate at very high power densities they can result into the required reactions forming intermediates like active species and free radicals. With the use of thermal plasma we can achieve fuel flexibility any kind of fuel from gaseous fuel to liquid fuels can be used and we can have a better control over the process getting the desired gas composition. There have been various demonstrations with different plasmatron and it has been observed that a composition that the 40 to 50% of hydrogen in the product gas composition could be achieved with a specific energy consumption of about 40 mega joule per kg. Since this is reforming is a highly endothermic process so better conversion we can get with thermal plasma method compared to the non-thermal plasma and that also with RF or microwave powers. To summarize this part there are various plasmatrons which have been demonstrated for plasma reforming of methane and other hydrocarbons and there are certain parameters that needs to be varied to optimize and achieve higher conversions and get better efficiencies. With the plasma reforming there are several advantages compared to the conventional reforming like we can achieve faster reaction so the start time is less the re-actors reformers are smaller and compact because we can achieve higher energy density and even short residence time. Wide range of fuels can be used for reforming using plasma reforming. We can have a good control over the process because this is in requiring an electrical energy input at the same time we can get a good control over the output gas composition or the product gas composition because the density of species generated can be controlled it can be controlled by gas flow rate, feed gas composition by the power of discharge. At the same time the poisoning of catalyst is less the tolerance to poisoning in the plasma reforming is higher and that carbon deposition tolerance is also higher. However there are certain associated disadvantages like we have to depend on electrical energy and the hydrogen which is produced is at a lower pressure. We can increase the pressure but then there are challenges associated with the erosion of the electrodes and its life reduces because of the less reduced arc mobility. So we have seen that how we can do steam reforming with the use of alternate energy sources like nuclear or solar or by means of electrical energy input using plasma reforming. Thank you.