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Claim My Discount!So, one can think in terms of. How do this, when we think in terms of a unit which we are comparing for having hot beverage like tea or coffee? How does this compare? So, there is this paper, the two papers by hawking, the first paper is a comparison of the paper cup with a polystyrene foam cup. (Refer Slide Time: 12:53) And there is another, so there is paper versus polystyrene cup and you can look at and there are we can also so for each of this, for a given amount of liquid to be the given capacity of the cup. So, in this case, this is an A towns cup and the entire life cycle analysis has been done. In the case of paper, it starts with the wood which is the wooden waste and in the case of the polystyrene it is using, it starts from petroleum as a feedstock in each of this the papermaking process is energy-intensive also requires water and other resources, has environmental impacts. So, based on a certain amount of cup, a certain quantity. The entire chain has been drawn up and based on that the amount of energy and materials which are embodied or required in this is calculated. So, just to give you an idea of how we look at ceramic, plastic, glass, paper and foam. We can, the weight of the material per cup, is given here and you can see the difference in this. The polystyrene cup is about one fourth this mass of the paper cup. However, the specific energy per kg is much higher for the polystyrene cup and the so the, but still the total and bodied energy lower than that of the paper cup. So, the hawking in his first paper mixes an argument that one thinks that the paper cup is likely to be environmentally better but he says that the plastic, the polystyrene cup turns out to be better than the paper cup. Of course, this is dependent on the kind of assumptions and the, so this is, and this comes out to be so you get point 2. If you look at `this the functional unit is one cup and each of these cups are of the same capacity and you can see this is 0.20 this is 0.55. When we look at re-useable cups ceramic, plastic and glass, and you can see the difference in the, you can look at the original papers so that you can see more of the details I am just giving you the final results, which will give you an idea of how this can be used. So, look at the cup mass the material-specific energy and then based on this when you multiply this, this gives you embodied energy or the energy per cup. Now, in the case of reusable cups, what would happen is that the number of reuses as well as we want to you know we want to sure this is done hygienically. So, this will mean that we will need the energy to wash and this the calculation which has been done by hawking is for using the cups in a dishwasher. And the energy used in an in per wash is computed and that is added. (Refer Slide Time: 16:39) And based on this we get, a situation like this depending on the number of uses you can see that. There is a trade-off between the foam cup and the paper cup and the reusable. So, if you look at the glass beyond a certain number which comes out here this is the breakeven number of if we going to use it for, let say 40 or 50 times then you can see that it is going to have a smaller energy per use will be much lower. However, if you are using less than 10 you can see that this is, this is lower than this. So, the paper cup turns out to be and for the foam cup you can see that it is it seems to be quite the energy use is lower than the requirement for the reusable until you go to a very large number. So, this is interesting. Of course, if we change the assumptions and how we process the results may change. So, if you look at this paper by Hawking in science, there was a cretic and then where was the discussion so the assumptions depending on the assumptions one makes about the process the things can change. Also, both in terms of polystyrene and paper the process and glass and ceramics there have been processing efficiency improvements, so this is relative all this are in the 1990s if you did the numbers today you would get slightly different numbers little more efficient as compared to the earlier. So, I would suggest that you look at both these papers and this will give you an idea of one of the earliest ways in which one has done the life cycle analysis and in energy, energy and environment impact analysis for something that we always look at the different kind of choices of disposable versus reusable. (Refer Slide Time: 19:19) Now, when we think in terms of different energy sources. If you look at. Let us say extracting coal or extracting oil in a period what happens is that if we look at an oil well. We have an oil well, we need to input different kinds of material will come in into extraction process. There is a certain about energy which is used, there is the axillary Self. There is gross energy input which is coming from the oil and then there is a net energy output. This is going to your economy. So, we would like to see nowhere if look at it there will be some materials and then there will be energy which is a purchase. So, typically it might use electricity and we want to look at this boundary. So, see all that we are using, which we have all that we are putting in is E self plus E purchase. And the energy return on investment is defined EROI as E net, E self plus E purchase. Now, there are many different energy sources. We do not take the content of the oil or the coal which is there in the ground whatever we are using in the process. And this can be done either primary or it can be done up to the final use. In final use, if we are looking at it up to the final use. It means whatever energy is being used in all the processing finally when we are supplying that energy and over the lifetime of this process what is the energy return on investments. (Refer Slide Time: 21:32) So, this is called energy return on investment. Just like we did the return on investment for the financial terms this means how much energy am I investing and how much energy I am getting out of it. So, typically what happens is in the case of in the early years when we had the oil well this energy return of investment was high. This has now been coming down, and if you look at this we can see there is a paper by Cleveland in the journal of energy, in the energy journal in 2005. And it shows the energy return of investment starting from the early 1900s and then going down, and so you see there is energy return on investment for oil has gone down, for coal and so on. So, this is of the order of 100 and it has is come down recently. (Refer Slide Time: 22:55) If you look at a coal-based power plant. There would be the energy inputs are all provided in the initial year. When it starts operating there is a whole set of embodied energy because you have the steels, you have all the material which are coming into the construct the power plant. And then so this is all the energy which is invested during the operation there is an axillary use which is the self-use and then there are material and other embodied energy which is the O&M. So, the net which we are generating is this and when you subtract this, this will be net output we can see how many years it takes to pay back for the energy which is invested in the life of the power plant. (Refer Slide Time: 23:49) Levels of Net Energy analysis D:Rangannea3.jpgSource: www.oilanalytics.org/neteng/neteng.htm And in all this when we do the levels of analysis we can look at different sets of the level. So, at the first level is we can just see in making the power plant what is the amount of embodied energy. That means we see how much of steel, concrete, steam generators, piping systems, the assembly energy so this is the this is one level of calculation. Then we can go to the aspect where we look at what is the amount of how much, how much energy is going into the production of the steel and then the iron ore which is coming into making that steel. So, we can go to that level we can also then look at what is the energy which is taken in making the equipment which makes all of this. So, one can go to different levels now when we go to the next level, you have to stop someone. So, you have to see if I go to the next level how much additional amount what percentage does it add to my overall numbers. So, at some points, we make that closure and then go ahead. So, one of the calculation is in all this we calculate not just the energy but we also look at what are the number of emissions which is coming in. (Refer Slide Time: 25:30) So, local and global just to show you an idea of the CO2 emissions of coal-based power you can see that it start with the mining, the transportation, the construction and power plant operation. And then this for, this is the study done by Mann and Spath NREL and this showed that most of it, the largest chunk of it is been is in the actual operation of the plants. Some of it 3% is for mining, 2% transport and so on. But predominately it comes to about kg of CO2 equivalent per kilowatt-hour. (Refer Slide Time: 26:10) A similar comparison has been done for biomass and the net energy is biomass is considered to be almost carbon dioxide neutral. Because what happens is that the biomass during its entire growth cycle acts as a carbon sink. So, if the CO2 which is recycled in this case is of the order of 890 grams per kilowatt-hour and the net CO2 emissions again depending on how we do the numbers is just 46 gram per kilowatt-hour as compare to that 1 kg per kilowatt-hour. And this feedstock production, the transport, the construction and the CO2 emissions here which gets absorb at that. And so overall there is 98% CO2 closure in IPCC considers biomass if it is done sustainably to be carbon neutral options. So, it is taken at as zero CO2. We had done a study and you may want to look at this study, where we had calculated the lifecycle greenhouse gas impacts of the coal-based power plant and if we wanted to instead of coal, if we wanted to import natural gas through the LNG, basically liquefied natural gas import it from the US, look at the entire lifecycle of that and then see what happens in terms of the CO2 point of view. (Refer Slide Time: 0:48) So, if we look at this, you will find that in the Indian context, the most of them as we saw, most of it is in the power plant itself, very similar to the Mann and Spath study. Here we got it as 1082 kg CO2 equivalent per megawatt-hour. Mine to plant has something coming in with the mining, at mining the CH4 emissions, fugitive emissions at the mine. Diesel and electricity use at the mind and the transport. So, this accounts for just 59 grams of 59 grams per kilowatt-hour or 59 kg per megawatt-hour. And so, this gives you a sort of break up, just from the this is cradle to the gate kind of calculation. (Refer Slide Time: 1:50) And if we look at a similar kind of thing for the, if we wanted to use imported natural gas, we find that the power plant accounts for much lower, the total comes down from 1000 to about 585. Here the well to the power plant is significant of which it starts with the this is where they are looking at a hydraulic fracturing and so, pack the production of the oil and then processing, the transmission in the US, liquefaction, shipping, regasification, that adds much more than the mine to, mine to the well. As in the coal case, where we started from coal mining to the very small power plant, this is much higher, but then the actual operation is much lower. So, overall it turns out to be less. (Refer Slide Time: 2:46) We also saw, based on this we made a distribution of the actual CO2 emissions for the coal fleet of the Indian, of India and you can see very clearly that the mean is around this. There are some plants which are, which are more efficient, maybe there are the supercritical ones, and there are some which are operating with a much poorer emission record. And in the case of natural gas, if we had this kind of distribution, you can see that the mean will be much lower than this. So, this gives you an idea of what is the kind of GHG emissions for the power sector and how we can look at it from an energy point of view. (Refer Slide Time: 3:29) When we look at energy return on investment, there is a recent paper in nature energy which you may want to look at, which calculates the EROI and shows EROI for different kinds of different sources, including renewables. So, we can look at the energy EROI based on primary will be whatever energy is used in the extraction and the production, but we can also look at the energy embodied and used in transmission and distribution and the final energy. So, finally, if we look at this as the framework, the EROI values that we would get would be lower than that we have, we would get only if we looked at the primary. (Refer Slide Time: 4:23) So, if we see this, this paper shows the EROI primary and the EROI final. And you can see over a period that the EROI’s have been coming down. And finally, EROI is we are talking of are of the order of about 30 or so which is also pretty high number. (Refer Slide Time: 4:49) This is a summary of different studies, EROI estimates and you can see here that the EROI estimates show for electricity for photovoltaic, the EROI final which we are talking of are of the order of 6 to 20, again depending on the different kinds of studies and the different kinds of estimates and assumptions which are there. (Refer Slide Time: 5:25) In addition to the EROI, there is another EPBT, which is energy payback time. So, if we look at the total amount of embodied energy in let us say a solar PV module, and see how much time does it take for us to generate that much energy. So, in the 1970s and 1980s the energy payback periods of photovoltaic was high, which meant that it would take a large number, a large number of years for that energy to pay back and for any new source which we consider as renewable, we can calculate this and see whether or not it is viable. So, apart from the EROI, we have another index called the energy payback period. (Refer Slide Time: 6:32) So, this is from an NREL report, you can see this NREL if you look at this document, it shows you the kind of energy payback periods for the entire PV system, which is of the order of three years or less. (Refer Slide Time: 06:52) And we can look at this data it happens this way that we put in all the energy in the initial period, this is when we build the PV cells, the balance of systems and then you get the returns over the years and that is, that gives you the. (Refer Slide Time: 7:24) So, when we look at the earliest environmental impact, systematic environmental impact of photovoltaic was done by Alsema and you can look at this paper in 2000, start with the raw materials, go to the material processing, the manufacturing, the use, the decommissioning, as well as some of it is recycled and then the treatment and disposal. (Refer Slide Time: 07:39) And with this, the energy payback periods that were done for rooftop and ground-mounted systems. Of course, this will depend on these solar installations and the efficiencies. And based on this, you can see that these payback periods are of the order of two to three years again depending on the kind of assumptions. (Refer Slide Time: 8:00) You can look at this paper and this will give you based on this, we can also look at the GHG emissions and you can see, we had seen this in the initial phase where we talked about the chia identity and we said that renewables are an option for us to reduce the GHG emissions, we said, as compared to 1 kg of CO2 /kWh roughly for coal. When we talk of all the renewables, they are all in the range of 20, 30 grams per kilowatt-hour. And so, this is, these numbers are got from this life cycle analysis, and one may look at this in a little more detail. (Refer Slide Time: 8:38) And there is a recent report from the European Union, which talks about the energy payback period of the recent cells. Again, with different kinds of efficiencies, monocrystals, silicon, if you see, it turns out to be of the order of about two years. And then the similar things you can look at multi silicon, cadmium telluride and so on. (Refer Slide Time: 9:06) This also gives you an idea of the total carbon footprint. We have later I will show you some numbers that we have done for an Indian context on a similar basis. (Refer Slide Time: 9:20) When we look at the final lifecycle analysis, normally you can use your calculations, you can do this on with an Excel spreadsheet or you can use MATLAB many, many of the researchers do use software for LCA and there are various software Simapro, Gabi, some of them are public domain software like open LCA. The advantage of the software often is also that they have databases which are available for different kinds of materials and that will reduce the kind of time that you need to make the analysis. Please also remember that these databases which are there for the embodied energy will have assumptions, will be based on a certain kind of mix, will depend on the country for which it is there, so, if you are doing something for India please make sure you know how that when you use an embodied energy for some materials, find out for which country or context it is there and is in the Indian context is it going to be similar? You will find in all of this software you will find that there are multiple criteria which are calculated including the different kinds of. So, there are different environmental emission factors which are there and then the emissions are computed, both local, global, so, you can see that our criteria for CO2 global warming, N2O, methane, CFC and then this can be converted into a CO2 equivalent. And there are ozone depletion criteria’s like CFCs, HCFCs and then there are acidifications, SOX, NOX, hydrochloric, hydrofluoric acid, eutrophication, and local photochemical smog, all of this, the toxicity, all of these parameters are there and one gets in the one gets a whole set of multiple criteria. Now, depending on your application, we have to look at these criteria, see whether they are beyond the limits, compare the criteria across different options and then take, then look at the implication in terms of a decision. (Refer Slide Time: 11:59) So, in many of these cases. So, basically what happens is this is from the IEA’s, assessment LCS, assessment of different sources and you can see what all are the adverse impacts for different kinds of sources and then these can be quantified one can see what kind of tradeoffs one can have. (Refer Slide Time: 12:23) Similar this is the LCA assessment report in terms of this is from the World Energy Council and you can see that this has the different kinds of CO2 equivalent, tons of CO2 equivalent per Gigawatt hour. And you can compare the impacts which are there for nuclear, for wind and photovoltaics. There are LCA has been traditional, has been very useful in seeing for instance when we link think in terms of replacing oil, we have been thinking in terms of using biofuels. And there is several different sources of biofuels, one can use biofuels based on waste, one can also have dedicated plantations for biofuels. And several countries, including the US and Latin America, have been having large energy plantations. And sometimes what happens in these energy plantations is one puts in a significant amount of energy in the fertilizers, in the agriculture, in the irrigation, and when you look at the overall it may or may not be net energy positive. So, there have been situations where there is a subsidized and so it looks like it is a viable option, it is renewable, but when you do the numbers, you find that this is net energy negative. (Refer Slide Time: 14:16) So, this is an example from a report, which is from science, wherein the state of California, they assess that corn-based ethanol is a net energy negative and is worse than gasoline, gasoline is the fuel which is used for vehicles in the US. (Refer Slide Time: 14:16) And if you look at it, this is the greenhouse gas emissions from gasoline, in terms of equivalent CO2, equivalent per megajoule of the fuel. And when we look at corn ethanol, there is a direct emission and then there is an emission which is because of the land-use change. And when you add this up, you can see that this turns out to be worse. And so of course, these are interesting because as we will see, when we talk about policy analysis. Policymakers usually like to have a solution which is a large-scale solution. So, we want to have a large amount of Corn Ethanol or we want to have a large amount of Jatropha. And then, because it seems to be renewable, one subsidizes it, but then maybe in some cases, this does not result in the impact that you expect and you are putting in more energy, you are putting in more emissions than you would have done if you just continued with the gasoline case. (Refer Slide Time: 16:00) So, this is now a study for Germany. You can look this is a paper by Kaltschmitt, where a biofuel rapeseed methyl Ester for transport is calculated and the way it is calculated you can see the paper to get the numbers, but just to show you what it means is that the total energy that you are getting per hectare. And this we are looking at plant production including fertilizer, harvesting, transport, oil extraction, and some percentage is going to, is attributed to the rapeseed oil which is being used for our fuel. And then refining esterification, some percentage going to be, this is what I meant when we talked about the allocation. So, 96% going to this, 4% going to the other byproduct glycerin and then final transport. So, the total annual comes to about 16,200 MJ/ha and if we look at this, so, per hectare, this is the amount that we will get and this can be compared with the energy content which we are using for diesel and we can then compare these again in terms of the emissions. (Refer Slide Time: 17:20) So, this comparison which was done in terms of primary energies, this is 16.2, 47.1 is diesel, the CO2 equivalent is 1594, and diesel is 3752. And so overall you can see, they could be in this it is, it looks like this is a viable option in terms of at least primarily it passes the test of emissions and energy. So, let us look at now another example which is from an Indian context, we had carried out there was a period when the government was very keen on having large scale Jatropha plantations. And at that time, we thought that it would be worthwhile it would be interesting to see, so there was the entire map of India you would see that there was a plan to have a large amount of Jatropha plantations. And one of the things which we felt at that time was that one needs to analyze and see whether or not this is a viable option. (Refer Slide Time: 18:39) So, this is the work done by one of our students who was interning in summer and we compared both Jatropha and another one which is Karanja, Karanja is a seed which is used in often in south India. You can look at Jatropha or Karanja and we start with the first phase which is the agricultural cultivation phase. In the agricultural cultivation phase, there is some energy going into seedbed preparation sowing, there is some fossil energy going into diesel and electricity and there is the energy going into the irrigation and fertilizers and herbicides, so that is the agricultural cultivation state. We then take that and transport then transport we are using some fossil and diesel. Then we have the conversion stage, where you have the cracking, pressing, filtration, transesterification. And then we have the fossil which is used in vehicle operation stage. (Refer Slide Time: 19:54) And based on this we calculated using the net energy ratio and net energy ratio this is another energy output, energy input and in this, we do not take we are only taking for the energy input, we are not considering the energy that is put in with the biomass, we are only looking at only the fossil input. So, this net energy for it to be viable, the net energy ratio must be greater than 1. And we can also calculate what is the megajoules per kilometre of vehicle driven, we can look at also the costs on a per ton and a per-kilometre basis. (Refer Slide Time: 21:08) So, when we did this, if you see this we had primary energy which was going in here, primary energy going at this point and then we head the transportation and cracking stage and for Jatropha and Karanja. So, we did the life cycle approach and we looked at energy output by energy input, NER greater than 1, the replacement would be viable prima facie, then we have to look at the economics, of course, NER less than 1, replacement not viable. Then we did the lifecycle cost, then annualize lifecycle cost and calculated. So, we can calculate based on primary energy, on renewable energy and secondary so you would like to see. (Refer Slide Time: 21:47) And the interesting thing is please look at this graph, these are all 2007 values. You can see that there are different, there are different kinds of combination depending on the yield and depending on the nature of the land. So, if you are using fallow land which has relatively low yields, we need to put in much more of irrigation and fertilizers and there are situations wherein the case of Jatropha where this is less than 1. So, the other cases where the yields are higher and we can get this is without the co-product, of course, if we are using the co-product, which is and we can market that and that has a value then, of course, it becomes greater than 1 for all cases, but if we are not using the co-product which is glycerol, then you see that it depends on the kind of land. So, if your yield is high then, of course, we are getting a NER of the 3 and in this case what happens is that this island, which is typically fertile land and so there is an issue of food versus fuel. In the wastelands where we are looking at if you put Jatropha, you would find that it is not viable, we are putting in much more energy than it requires. And then so this is the kind of case, of course, this is the kind of price that we get and the prices were is similar, slightly higher than the price of the fuel that we are getting ex refinery at crude. In the case of Karanja, we find that the situation is slightly better that is going to be viable in all the cases. So, whatever we looked at, we have looked at life cycle analysis, and net energy analysis, and we have looked at how to apply these and we have looked at a couple of examples. In the next module, we will take a few more examples to illustrate the use of net energy analysis and lifecycle analysis.
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