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Module 1: Basics of Energy Use and Environmental Impact

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Energy and Environment Impact

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Welcome to the second lecture in the course on energy resources, economics and environment. In this class we will be focusing on energy and environment and the environmental impacts of energy systems. (Refer Slide Time: 0:30) In the last lecture we looked at the energy flow diagram and we saw how, whenever we want to use energy the final energy that we use in terms of the energy service or the end use activity, in order to get that we have the primary energy, the energy that is available in nature which goes through a sequence of conversion steps before we get the final energy service. So at each of these steps, some amount of energy is used and in using that energy there is also some adverse impact and there is an environmental impact. (Refer Slide Time: 1:16) So we are going to try and look at this We also saw in the last lecture we looked at the whole phenomena of growth and we looked at the world having a tendency to grow, we have everything in terms of the population grows exponentially and all other parameters follow that exponential pattern. So when we look in terms of the water use or the energy use we said that there would be exponential or unbounded growth.When we look at unbounded growth, the area under the curve when we take it to infinity is infinite. So when we think in terms of a finite resource situation or the finite ability of the world to maintain and to look at the ways that becomes a problem. So the whole issue is when we design energy systems and these energy systems grow, what are the kind of impacts that happen to the environment and are these impact going to be sustainable into the future. (Refer Slide Time: 2:18) So the issues that we are going to discuss in section related to the environment, the first one is why is the environment important? How do the energy systems impact the environment? Is there a trade-off between environment and economic development? What are the major impacts and causes? How do we quantify these impacts and how do we ensure a sustainable future? So, we will take a quick snapshot of why the environment is important to us? What isthe impact of the energy systems on the environment? And how do we do this quantification? (Refer Slide Time: 2:53) So if you look at this figure, is from the book by Tester on sustainable energy. When we look at an energy system, we are talking of either exploration or production or conversion or utilization and in doing that we are using some natural resources, we are using some human resources and in the process we are then generating, we have the useful effect that we want which is for instance cooling or heating or the transport. So, there are useful goods and services, but in producing that there are unintended impacts that we cannot avoid and these impacts, some of these are listed here, so you have solids, liquid and gases, effluents or pollutants which go out into the atmosphere into the air, into the land, into the water and each of these depending on the concentration, depending on how you treat it, how you send it out will have different kinds of impacts either on humans or on theecosystem. Then there is ionizing radiation, the electromagnetic radiation, aesthetics in manty cases for instances when you have large wind turbines and you look at these wind turbines in thelandscape it affects the patterns of birds and its effects the aesthetics some several local communities are not necessarily in favour of this and so this also can create problems. Many of this situation when we use a certain amount of energy we also reject some heat which is a waste heat and this causes for instance when you have cities and you have a concentration, you have an urban heat island effect where some portions of the cities would have a much hotter temperatures and then there are ways in which we try to mitigate this. Sound for instance if you look at a large compressor or you look at a power plant these would be a sound and that also has an impact on humans staying in the vicinity, electromagnetic radiations. So these are all these unintended impact and these are the impacts that we need to quantify. Typically, the way this happens is that we start with using the energy system and we start using more and more energy to make our life’s more comfortable. Many of these problems then get into a, they accelerate and it gets to a level where the problem is seen as a problem that needs solution and then we try to modify the energy system, so this is the way in which it happens. (Refer Slide Time: 5:51) So for instance if we look at typically when we look at all the energy that is being consumed, if you are looking at fossil fuels which is today the present mode of energy consumption, whether it is coal, oil, natural gas the bulk of our energy use today is still from fossil fuels and if you look at the use of these fossil fuels, we have the pollutants or the we let out these gases into the atmosphere and for instance there are sulphur dioxide this happens through industrial processes. This sulphur dioxide also comes in the power plants, nitric oxide again from power plants in industry, carbon monoxide from vehicles as well as from industrial processes, solidparticulate matter and in this particulate matter it is also important to see what is the size range, so we talk of PM 2.5, PM 5 the smaller the particle size the larger the impact in terms of health and so we monitor some of these and this is one of the things which is contributing to air pollution and urban air quality and respiratory health impacts. Carbon dioxide in chlorofluorocarbons and we will talk about these, these are global pollutants. So all of these have different kinds of impact, so one is its modifying the atmospheric properties or processes in the case of sulphur dioxide and SOx, it combines and then it can cause precipitation, acidity which is called acid rain and that can corrode variety of equipment, there can be smog photochemical smog, it can affect visibilities. So for instance on days when you have a navy day and you are trying to see out into the ocean often there are restrictions in terms of vehicle movements so that the visibility can get improved and corrosion potential, radiation balance alteration, this is will talk about this little more in detail in CO2 and ultraviolet energy absorption. So the impacts can be at the local regional or the global scale and these are just some examples of air pollutants which have an impact on the environment.(Refer Slide Time: 8:22) So the adverse health impacts can be going from mainly based on local and we can go from local perturbations to global disruptions as the human energy use increase. In the early 80’s Professor John Holdren of Harvard University proposed an index called “The human disruption index” and this was to look at what is the disruption at a global scale of a particular pollutant. This is defined very simply as the ratio of the human generated flow of a given pollutant to the natural or the baseline flow. So the idea is that, in case the human generated flow of a pollutant is orders of magnitude less than the natural of baseline flow then nature has the ability to manage it and nature will have the system it will not show up as a problem, but the moment it becomes of the same order ofmagnitude as natural or baseline flow, then there are problems because in the human impact is something which nature is not able to regenerate or absorb. (Refer Slide Time: 9:42) And so if you look at these ratios, these were the human disruption index which weretabulated by John Holdren and you will see the disruption index lead emission, oil to oceans, cadmium emission, sulphur emissions all are greater than 1 and you will also see on this side that a large percentage of this is because of the energy sector and energy use. (Refer Slide Time: 10:29) So energy and its impact the current way in which we are using energy has an adverse impact on the environment and this is why we need to change the way look at efficiency, look at ways to mitigate, nitrogen fixation again if you see Di mercury emissions, nitric oxides, particulate emission, carbon dioxide and you can see all of these are showing up as problemsbecause the human disruption index is greater than 1. (Refer Slide Time: 10:38) So we go forward in this in that if you look at the energy flow diagram that we discussed, at each element of that energy flow wherever there is a conversion they will be associated with it some emissions. So if you look at some electricity which is being used in the household, in order to get that electricity we start with the mind, if it is coming from coal, it is the coal that we are mining. So at the mine itself there are some emissions which are going into the land and the water there are emissions which are there in the air pollution, then that mine goes to a cold bay there is a transport and that has some emissions, then it goes to a facility where you arebeneficiating the coal again at that point there are some emissions, the transportation has associated with some emissions, then you have the power plant which has the bulk of the major emissions and then we take it to the transmission to the household. So you can see that we have to calculate the emissions over the entire cycle of use, entire fuel cycle. So just like we looked at the total energy used, we can look at the total emission. (Refer Slide Time: 11:56) So now the question which arises is – what is safe for humanity? What kind of regime is safe for humanity? And a group of researchers lead by Professor Rockstrom worked on this and there is a paper in nature which I would urge you to read which is published in 2009 it iscalled the safe operating space for humanity. So what the  researchers did is they looked at a large number of different parameters and they looked at what were the natural equilibrium for these parameters before we started industrial activity and then based on that they also identified through some models that how much, what is the limit for that criteria. So with that they identified a set of 9 different criteria which were critical for humanity to operate within a certain safe regime and in those 9 criteria they identified 3 where we had already exceeded the limits. (Refer Slide Time: 13:16) So, I will suggest that you look at this the papers starts off by saying that the history of human development has had a number of different eras and if you look at the history of theworld on large time, large time scale means we are looking at thousand, hundred thousand years so that axis which is there on this graph is starting from here 0 to 20,000 40,000, 60,000, 80,000, 100,000 years before and in this year trying to see what is stable environment for the earth as far as we know the earth is the only planet where there is life and this isbecause we have the atmosphere which maintains the temperature constant at a particular value. Seen here is an isotope of oxygen which is a proxy for the average temperature and if you look at this you will see that in nature we have had different kinds of eras and in all of these eras there has been a significant fluctuation in the temperature and the climate. It is only in the last 3, 4 thousand years where we had we have enjoyed the relatively stable environmentand this is the period where actually life evolves and the civilizations evolve. This is called the Holocene and this is the period where we had significant growth and we have had significant development and improvement in human kind. This is now threatened by human activity and the geologist have coined a term where this is called now we are now going into the Anthropocene. Anthropocene mean this is an era where it is human activity that is dictating the changes which are happening on the earth and on the earth’s climate and this Anthropocene it has been shown that is not something that it is going to be sustainable into the future unless we make some changes in the way we develop and operate our energy systems. (Refer Slide Time: 15:49) So in this paper they looked at a number of processes at a planetary scale and three of these processes are climate change, ocean acidification, the stratospheric ozone and there are also aggregated processes from the local and regional scale that means chemical pollution, biodiversity loss, land use change, freshwater use, atmospheric aerosol loading, globalphosphorus and nitrogen cycles. (Refer Slide Time: 16:14) And in all the cycles, you can look at the paper for details there is a proposed boundary, there is a current status and then there is a pre-industrial value. So for instance for climate change the pre-industrial value is 280 parts per million by volume of CO2 and the proposed 350 partsper million by volume and current status has gone up. (Refer Slide Time: 16:41) And in this if we look at it this shows you where we are exceeding the limits and you can see that we have exceeded the limit on the rate of biodiversity loss, the nitrogen cycle and the climate change cycle and we will discuss the climate change cycle in a little more detail. (Refer Slide Time: 16:57) So in the case of CO2 as I mentioned to you earlier as we know the only planet where there islife is the earth and the reason for that is a thin layer which is the atmosphere and in the atmosphere we have the main constituents are nitrogen and oxygen, carbon dioxide is actually at a relatively lower concentration but carbon dioxide has an important parameterwhich is radiative forcing. So carbon dioxide actually permits the incoming radiation to come in but traps the outgoing with the result that it increases the overall temperature and the radiative balance created by this CO2 concentration results in an average temperature of land and water of 15.5 degrees. If you look at a greenhouse, you will find that in a greenhouse the, because the greenhouse trapsthe outgoing radiation and does not permit it to go out, the temperatures are higher and this improves the growth of the plants.So in a similar fashion if this CO2 concentration is increased, we will have a temperature rise on the surface of the earth and this will affect the climate patterns. You can look the evidence, of course there is a natural variability as we saw when we looked at the thousands of year time horizon, you can look at the evidence that this there on the IPCC. There is a inter government panel on climate change, www.ipcc.ch, you can look at that site there are reports on the science and technology option and on climate change and that will give you all the evidence. Now, if you look at this graph, you can see that CO2 is a critical gas in terms of radiative forcing the others are CH4, nitric oxide and then there are other effects of aerosol in moisture. (Refer Slide Time: 19:27) So we are basically going to focus on CO2 this graph shows you the time series evolution of carbon dioxide in the atmosphere. Now this is for a thousand year time horizon, the first question that should may come to your mind is that was this a problem over the last thousand years and how we have been tracking it. So the earliest initial mention of this problem ofcarbon dioxide and climate change problem happened in 1950’s and only since the 70’s there has been serious efforts in the IPCC. So when we look at a thousand year time horizon, this record is something that is actually available to us in nature. So, if you see on this graphs on this side you have this image we have these expeditions to the arctic and the Antarctic where scientist actually go to the ice cores so typically when you look at in the ice which has been formed at depth that ice has been formed at a different periods of time and based on the isotope of carbon one can actually identify what is the age of the ice based on the depth. Once you look at the age of the ice and you have the ice core, the air which is trap at aparticular is the air which was there when that ice was formed, so we have the year and we have the air, we can look at the composition of the air and that will give us a frozen record of what was the CO2 at the time when that ice was formed. So you will find if you just Google you will find many different expeditions and all of them have a similar kind of plot. So if you look at this plot on the X-axis it is the age of the air, so we start from, let us say 2000 and going back a thousand when thousand AD when the ice was formed. So, at different depth this will be at a higher depth and on the Y-axis is the carbon dioxide mixing ratio what is the percentage of carbon parts per million by volume of CO2, so that gives you the CO2 concentration in the air. And if you look at the first from 1000 to about 1800, around 800 years you will see if we get, got this kind of data in a laboratory experiment you would say that this is more or less constant it is process under control, there is some variation but it is within plus minus 5 ppm. So you see this level the straight line that we draw here is at 280 parts per million by volume and this is the pre-industrial equilibrium of CO2 and this is what the earth can take.Then what happens? You will see that it is almost like the second curve which I have shown here, this curve is has a different trend completely, this curve represents the trend that we had seen in all these other cases where we have population growing exponentially anything that humans are consuming growing exponentially.So this has an exponential growth rate, so clearly there is a diversion from the equilibrium and what happens here, so this is the point where we had the industrial revolution we had James Watt in the steam engine and we had the use of coal to use to develop industry, to create mines, to have power and this is where we started using more and more coal and more and more oil and natural gas.And so we have two things we have the fact that CO2 has a radiative forcing component and that all life on the earth depends on the equilibrium temperature, radiative component with an increase in the CO2 concentration would imply and increases in the global temperature and this is what is called global warming and this is would result in climate change. There are large scale models operating where you can try and figure out what will be the impact there are uncertainty of course in the model but what is reasonably certain is that in any case this is a disruptive effect which we need to mitigate, which we need to we cannot continue with this kind of exponential growth of the CO2. (Refer Slide Time: 24:32) Now, to look at this in more detail there is been, from the 70’s there has been a trend of actual measurements an observatory Mauna Loa in Hawaii in the U.S and you can see this on this graph and you can see and you will see when you look at this graph you can see very clearlythat it goes to ups and downs. Now when you observe this carefully, you will see that one crest that is the peak and one turf happens every year and this is how but overall there is a sort of exponential growth but it goes through a turf and then a crest and so this is this peak. Now the question is why do we have this seasonal kind of variation we have a number of reason which you can think about is it because the CO2 concentrations show an increase over several years but fluctuate randomly within the year or the seasonal fluctuation in the CO2 constructions is due to seasonal fluctuation in the energy pattern. Seasonal fluctuation is due to local fluctuations in Hawaii, seasonal fluctuations are due to ice melting in summer or none of the above. So if you think about it you will find that well this fluctuation is not random, there is clearly an increase in trend and clearly there is an annual pattern, so it is not the first one which istrue. The second one which you think of seasonal fluctuation in the CO2 concentration is due to seasonal fluctuations in the energy pattern. If you want to check whether this is true look at annual energy used over the globe and see whether that changes over the seasons and you will see that there is a trend of increase of the years but there is no clear cut seasonal pattern, so this also is not true, this is a CO2 is a global pollutant this is not due to local fluctuations in Hawaii, if you did this in some other place also you would get the same effect. And ice melting is summer does not create enough of an impact to be able to show this, so the answer actually is none of the above. The reason for this is because of the trend in the growthof vegetation and there are deciduous trees which will grow and grow in a particular season so that the CO2 sync increases in a particular season and decreases when there is a fall and because of that growth and CO2 absorption capacity vary we see this kind of trend. (Refer Slide Time: 27:30) So, let us move on, there is a website you can look at that and I looked at this number in recently in the month of June 2019, but you go to CO2 now and you can see the CO2 concentration, so we said to 280 parts per million by volume was the pre-industrial we are already on this particular day the average is about 415 parts per million much above the norm that we have set in terms of 350 parts per million. And so this is the problem that we need to mitigate. We have a situation where we have an energy system which is having these kind of CO2 emissions. (Refer Slide Time: 28:05) Now, when we look at we talked about the 280 parts per million by volume as a natural process and something which is coming through an equilibrium. So we can look at the carbon balance. There is this paper in the annual review of annual research of earth planetary earth and in these annual reviews can see that there is the carbon balance, there is already carbon in the fossil fuels, there is carbon in the ocean and there are flows. And in the flows that we are talking of there is an equilibrium in the atmosphere and then there is a flow which is coming in true, because of decomposition there is respiration and then there is human generated activity. So, in this carbon dioxide can carbon balance, it is the human activity which is causing the imbalance which is then related to the change in the concentration and this is something that we need to try to mitigate. (Refer Slide Time: 29:18) So the indicators of the human influence of the atmosphere again this is from the IPCC report you can see we talked about CO2 but we can see that similar kinds of things are visible when you look at methane, nitrous oxides, look at sulphate aerosols, so these are all human generated impacts and these are things where as we design energy systems we have the option of redesigning the energy system or we have the option of mitigating, trapping it, capturing it. So these are some of the things that we. (Refer Slide Time: 29:59) And we talked about the radiative this is another from the IPCC another figure which showsyou the kind of radiative forcing components. (Refer Slide Time: 30:01) Different pollutants that we talked of have different lifetime in the atmosphere, so it is not just about today’s pollution if you are looking at CO2, it lasts in the atmosphere for about a 100 years, so it is a cumulative effect that we need to calculate and that is this is captured in the form of a global warming potential. CO2 is considered to be one and the equivalent value for all the other gases is converted and these are the numbers. So what happens is that some of these like SF6 and the chlorofluorocarbons have significantglobal warming potential, so even though they may be at much smaller or trace levels they may have a greater impact. So everything which is calculated in the case of global warming is usually done with the CO2 as a baseline. So when we talk about CO2 we also talk about CO2 equivalent and we take all the other gases and convert them into CO2 equivalent. So whenever we talk in the course, we will be mainly talking about CO2 but please remember this means CO2 plus the equivalent of CO2 from other gases which are also creating global warming. (Refer Slide Time: 31:33)