Arquivo de etiquetas: Economia do Carbono

Lectures / Readings

The Deep Decarbonization of Energy Systems III

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The 3 Pillars of the Deep Decarbonization of Energy Systems

Welcome to chapter three of lecture five. I kept you waiting and I’m really sorry for that, but now is the time to start to looking at the solutions to the challenge of the deep decarbonization of our energy systems. How can we do it, that is the question? And in particular, how can we do it while making sure that we satisfy the conditions for continued economic growth and development and making sure that there is growing prosperity over the globe. This is precisely what we’re going to discuss in this chapter.

But first let me recap what is the scale of the challenge. As we discussed previously, CO2 energy related emissions are of approximately 32 gigaton today, gigaton or billion tons. To have a likely chance which let me remind you, we defined as a probability higher than two-thirds, higher than 66%, to have a likely chance then of staying within the 2-degree limit, the need to get down to approximately 11 gigaton by 2050.531

By comparison, to have a 50% chance only, so only one of out two of keeping below the 2-degree limit, the need to reach approximately 15 gigaton by 2050. So we’re roughly talking of a division by a factor two or even three of CO2 energy emissions in the next 40 years.

When in the meantime the world population is expected to grow and it is expected to grow by approximately one-third by 2050 compared to today.532

And the world GDP is also expected to grow and much faster in fact than the world population. It is expected to be multiplied by something like three by 2050 compared to today. So if we combine these different numbers together it means that we’re talking of dividing emissions per capita by something in between two-thirds and three-fourths by mid-century. And dividing emissions per GDP by a factor of six or nine by 2050, which is huge.

And so how can we achieve this decoupling between population and GDP growth on the one hand and energy consumption and CO2 emissions on the other hand?

If you’ve looked at the number, this is by any standard a major challenge, but this is certainly feasible. And I want to show you how.

The easiest way to understand how that can be done is to decompose the drivers of CO2 emissions. CO2 emissions can be expressed as the product of four inputs. CO2 emissions equal population, that is the first term multiplied by GDP per capita, that is the second term, multiplied by energy use per unit of GDP, that is the third term, multiplied by the CO2 emissions per unit of energy, that is the fourth term. If you multiply these four terms, you get simply the CO2 emissions.

I’m just decomposing CO2 emissions into these four terms to explain you where the emissions come from and in turn, to explain you how the emissions can be reduced, through which mechanisms in particular.533

If we take as a given the population trajectory and if we assume a rising trajectory of GDP per capita, in line with successful economic growth and, and development, then the CO2 emissions are driven mainly by the two last factors out of the four.

The first is the energy divided by GDP. And the second are the CO2 emissions divided by energy.

The first term is what we call the energy intensity, meaning very simply the amount of energy per unit of final output. The amount of energy we consume per unit of GDP we produce. The second term is the carbon intensity of energy, meaning the, the amount of carbon emissions per unit of energy we consume.

So let’s look at the ways in which we can reduce these two different ratios?534

So first, the energy intensity of GDP or as I said very simply, the energy consumption divided by GDP. It can be reduced through what we call energy efficiency and energy conservation measures in all the energy end use sectors. And we’re going to look in detail at each of them. First, passenger transportation and freight transport. Second, residential and commercial buildings. And third, industry.

So what’s the difference in between energy efficiency and energy conservation?

Because I just used both. Well usually we call

  • energy efficiency the technical improvements of products and processes. And we use the term,
  • energy conservation to describe a broader set of measures, including not only technical improvements, but more profoundly structural and behavioral changes that lead to lower levels of energy consumed per unit of GDP.

So let’s simply look at some examples to be very concrete and very precise. Examples of energy efficiency and energy conservation measures in the passenger transport and freight transport, for example to start with.535

  • Well first, improved vehicle technologies. That is more efficient vehicles. Vehicles using less gasoline for example per kilometer traveled.
  • Second, what we can call smart urban design. You can think at least of two things. One, building public transportation systems to reduce the need for the use of private cars, but you can think even more profoundly about building cities in a way that minimizes the distance to travel from where we live to where we work. Again, reducing the need for private transportation cars.
  • Third example. Optimized value change. Again, to minimize the distance, but this time the distance we need to ship the products from where they are produced to where they are consumed.

If we look at the residential and the commercial building sector, we can also think of a number of different options.

  • First, improved end use equipment. So more energy efficient equipment in our buildings.
  • But also what we could call smart architectural design. So building our houses in a way that reduces the need for cooling or heating for example.
  • More generally, improved building practices to improve the energy efficiency of the building envelope and also the use of different, less energy intensive construction materials.

If we look at the industry sector, again, many different options for an energy efficiency such

  • as improved equipment and production processes,
  • material efficiency, but also very importantly because the industry is a huge consumer of heat to produce its products.
  • So reuse of waste heat is an important part of the energy efficiency measures in industry.

536So that’s it for all the different ways in he different sectors in which we can improve the energy efficiency of GDP.

So the ratio of energy consumption divided by GDP. But as I said, it’s not the only driver of possible emission reductions.

We now need to looked at the other term, the improvement in the carbon intensity of energy or the ratio of CO2 emissions per unit of energy consumed. And here too the carbon intensity of energy can be reduced in two different ways.

The first is and very importantly, because it’s really at the core of any successful deep decarbonization strategy, it is the decarbonization of electricity generation. So as I said, your objective is the replacement of the uncontrolled fossil fuels, the phase out of the uncontrolled fossil fuels to produce electricity by a mix of different options, because there are different options to produce electricity with no or very little CO2 emissions.

The first is a mix of all different sorts of renewable energy such as hydropower, wind power, solar power, or geothermal energy. But you can also think of using nuclear power or using the fossil fuels, so the coal and the gas used to produce electricity, but with carbon capture and sequestration. So that’s a first important way in which we can decrease the carbon intensity of energy, by decarbonizing the way we produce electricity.

There is another way which we call fuel switching. It means switching end use energy supplies from highly carbon intensive fossil fuels in transportation or in buildings and in the industry to lower carbon fuels. Electricity is of course one of these possible lower carbon fuels, provided it is decarbonized. But there are other possible forms of lower carbon fuels and in particular, the use of biofuels. So again, this is another way of reducing the carbon intensity of energy which we call fuel switching, switching fuel from high carbon to low carbon sources of energy. So let me summarize.

The deep Decarbonization of energy systems rests on three pillars.

  • The first is energy efficiency and conservation measures.
  • The second is the production of low carbon electricity.
  • And the third is the switching of fuels from high to low carbon energy carriers.

I want to stress here that electricity plays a pivotal role in the deep Decarbonization scenarios because you see electricity in two out of the three pillars.

  • First you see that electricity needs to be almost completely decarbonized and we’re going to come back to that in a moment.
  • But also because electricity overall plays a more important role in energy consumption as fuel consumption switches from high carbon to low carbon options.

It is very important that you remember these three pillars because they really represent the basic framework to think about the deep decarbonization of energy systems in any circumstance. As we’re going to see in the next lectures, the precise options within each of these three pillars, but also their relative importance is going to vary of course from one country to the next. But these three pillars really represent the basic foundation to think about deep decarbonization.

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Lectures / Readings

The Deep Decarbonization of Energy Systems I

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What is an Energy System?

Today’s lecture is an important milestone in this course, an important turning point, because so far we’ve been mostly looking at the problems of human-induced climate change. But today, good news, we’re going to start looking at some of the solutions.

Up until now you might think that the picture looked quite grim, and you would have a point because indeed the potential consequences of uncontrolled climate change are very severe, very threatening. And the challenge of avoiding dangerous climate change is also very significant. It requires very deep reductions in greenhouse gases emissions to 511eventually as we discussed in the previous lectures, net zero emissions by the second half of the century. We also mentioned that it, in turn, requires a profound transformation of the way we grow our economies and in particular, a fundamental transformation of our energy systems. But the good news is that this is feasible. This is certainly not easy, but this is feasible.

And today we’re going to start looking at some of the possible solutions to the deep decarbonization of our energy systems. We’re going to do so first at a pretty high level, looking at the solutions at the global level first, but for each of the key sectors of the economy, the energy supply, the industry, the buildings, the transport sector. But in the next lectures we will take a closer look at these solutions by looking in detail at country-specific case studies and also by looking in detail at some of the most important technological challenges such as carbon capture and sequestration, or new generation of nuclear power, or the challenge of having smart grids and energy storage to be able to operate our power system with a high share of intimate and renewable energies, or the challenge of having long-range electric vehicles.

But before we do that, we need to have a good understanding of how our energy systems function. And this is what this first chapter is about. I want you to understand how energy is produced. I want you to understand how it is transformed and how it is consumed because we need that to understand how we can decarbonize our energy systems. The truth is that energy is everywhere in our daily lives. We use for example energy to transport ourselves.512

We use energy to light, to heat, to cool our homes. We use energy also to power our TVs or our computers or our washing machines and fridges. But energy is also absolutely central to the process of economic growth and development because we need energy to produce all the goods we consume. We need even more energy to be frank, to produce the kind of construction materials such as cement or steel that we use to build the infrastructures that support our economic growth and our development. And we also need a lot of energy to ship all these products from where they’re produced to where they are consumed. There are many different sources of energy.

Let me make a short list. We have coal. We have oil. We have gas. We have hydro energy, nuclear energy. And also all different sorts of renewable energies such as solar, wind, or biofuels. We call these different sources of energy the primary energy. And the table you can see is what we call an energy balance. And the different sources of primary energy can be read in the columns to this table. The primary sources of energy can either be used for direct, final energy consumption or they can be transformed into another form of energy, because before their final energy use in energy end use sectors such as transport, buildings, or industry.

Let me take an example to illustrate that point. Coal can either directly be used to produce heat for buildings or different types of industrial processes or it can be used to produce electricity which in turn is used for lighting or to power any electrical equipment. There are also many different types of energy transformation processes which you can read in the lines in the middle of the table. Again, let me pick just three examples. Power plants, very important type of energy transformation process.

The power plants use all different sorts of primary sources of energy such a coal, gas, hydro, uranium, all different sorts of renewable energies to produce electricity. Second example, the oil refineries that transform crude oil into oil products that can be used by ars or by planes. Heat plants that use coal, gas or biofuels to produce heat for buildings or industrial processes.

There are energy losses happening during these transformation processes. And these losses represent the difference between primary energy, and final energy. And, and you can see the final energy end use sectors at the bottom of the table. You see the names of the different sectors, industry, transport and on the graph, other, which in particular includes buildings. The transformation and the consumption of some forms of energy, not all of them, leads to CO2 emissions and therefore contributes to global warming. Some types of energy have no direct emissions such as nuclear power, hydropower, or renewable energy such as solar or wind.

Even if it’s…. And it’s important to mention in, they might induce some emissions through their life cycle, but they have no direct emissions. To the contrary, the burning of fossil fuels, the coal, the oil, the gas emits CO2 through the burning process. And of the three fossil fuels, coal has the highest CO2 emissions content per unit of energy. Its carbon content is on average across the different forms of coal, 22% highest than oil and 68% higher than gas.

So to summarize this chapter, the ultimate objective of the deep transformation of our energy system really is the phasing out of freely emitting fossil fuels. I underline “freely emitting” here because fossil fuels could continue to be used with some technologies and in particular with carbon capture and sequestration. But the uncapped fossil fuels must go, they must be phased out.

511511And we’re going to see in the next chapter that this is a major challenge because fossil fuels still represent the lion’s share of our energy consumption. And in fact an ever-growing share.

Lectures / Readings

Growth within Planetary Boundaries III

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The Case of Energy

Of all of the problems of reconciling growth with planetary boundaries probably none is more urgent and none is more complicated than the challenge of energy. Remember that the whole world economy grew up, starting with the steam engine, then the internal combustion engine, the gas turbine as a fossil fuel built world economy. Fossil fuels, coal, oil, gas, have been our friend. They have been the basis on which the modern world has been built. And indeed until James Watt in 1776 came along with his steam engine, there was no way to even think about sustained economic progress. Where would the energy for industry come from? Every time industry would start to develop in the pre-steam engine age, so many trees would be chopped down to feed the boilers that the limits of industrialization were very quickly reached. It was fossil fuels that allowed the breakthrough to the era of modern economic growth. I emphasize this because that history reminds us of how deep the challenge is. Right now fossil fuels are not our friend because when coal, oil, or gas is burned the carbon that is the basis of those fossil fuels combines with oxygen and produces CO2, carbon dioxide, which is emitted into the air, which is the main greenhouse gas warming the planet, changing the climate, and endangering humanity and other species. And so what has been the key at the very core of the world economic growth is now at the core of our major problem. Well, you might say use less energy, but it’s not so simple.

Because as a physicist will remind us, what is energy? Quality energy is the ability to, to work. Any useful work in, in economy depends on energy. Sure, we waste a lot of energy in the form of release of heat or friction or driving cars much larger than they need to be or poorly insulated buildings. So energy efficiency is clearly part of any solution for sustainable development. But the world needs energy resources, will use energy resources, and the use of energy, even with a substantial gain of efficiency, is likely to increase in the aggregate as the world economy expands by factor three or by factor four as we have just seen. And so we have a problem. More energy is needed. The traditional forms of energy, the fossil fuels of coal, oil, and gas, can’t do it for us because that would create a massive intensification of the climate change problem. How big of an intensification?

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That’s what I’d like to discuss, so that we get some parameters of where we are and where we’re going. This graph shows again on a logarithmic scale on the horizontal axis and on the vertical axis the income of different countries and the primary energy use of those countries, the energy consumption. Total energy use by country would include the fossil fuels, it might include wood burning, hydroelectric power, geothermal energy, wind and solar power, nuclear power or some other forms for instance biofuels. And what is done in this graph is for every country in the world to measure first the total output measured as the gross domestic product, and then to compare that with the total primary energy use. Which can be expressed in a number of ways, in units of kilowatts, or kilowatt hours, it can be expressed in tons of oil equivalent energy where, you take the amount of energy in one ton of oil, and then for all the other kinds of energy, whether it’s coal or gas or hydro and so forth, you look at the amounts of, of energy available from that resource and convert it as if it were tons of oil that had that much energy potential. And then express all the different energy sources with these conversion factors as a tons of energy equivalent amount of primary energy use. What you see when you graph the total output of an economy versus its energy consumption is essentially a straight line, though of course the countries don’t fall exactly on this upward sloping line. What this line signifies is that a doubling of the size of an economy tends to be associated with a doubling of primary energy use. Energy use scales alongside in proportion and in relatively constant ratio with total size of the economy. So, as the economy grows the energy use will tend to grow along side it. Save for break those in technology that allow for greater energy efficiency.

Lets look quantitatively at how much energy we use and what that implies for how much carbon dioxide we therefore emit into the atmosphere and what that implies for how much climate change we’re causing.

If you look at the amount of energy use by country you find that, roughly speaking, this is on average because countries differ, but they don’t differ all that widely. For every $1,000 of total production in the economy, the total energy use expressed in tons of oil equivalent tends to rise by about 0.19 tons of oil. What is 0.19 tons of oil? These are metric tons. So, a metric ton is 1,000 kilograms. So, 0.19 of a metric ton is 190 kilograms. So let me put it again this way. $1,000 of production, on average, expressed in, $2,005, let me add one more, parentheses, is associated with about 190 kilograms of oil use, or an equivalent amount of energy contained in coal or natural gas or one of the other non fossil fuel forms of energy. That gives us the scale of how much energy we use for each $1,000 of production. Now, if you look at the mix of, the energy sources in the world, mostly fossil fuels, but also some nuclear power, some wind, some solar, some some charcoal from trees some biofuel say from sugar cane converted to ethanol for automobile use as in Brazil. On average, every ton of oil equivalent energy is equivalent to about 2.4 tons of carbon dioxide emissions. In other words burn a ton equivalent of energy, and you put up more than two tons of CO2 into the atmosphere.

How much CO2? That depends on exactly which energy source you’re using. If it’s nuclear power, zero, because nuclear power is not a fossil fuel, and therefore nuclear power does not by itself create carbon dioxide emissions. If it’s coal, it’s higher than that average because coal, being almost all carbon with some impurities, when it burns, creates CO2 with little other energy created by the coal. And so coal creates the most carbon dioxide emissions per unit of energy of any fuel. Gas, and natural gas and oil emit less. So coal for a ton of coal burned, you get about four tons of carbon dioxide emitted into the air. For a ton of I should say not for a ton coal but for a, an amount of coal equal in energy to one ton of oil. That’s the right way to say it. You get about four tons of CO2 emission. For one ton of oil, you get about 3.1 tons of CO2 emission. For the amount of natural gas equivalent to a ton of oil in it’s energy content, you get about 2.4 tons of CO2. And for hydroelectric power, for solar power, for wind, zero.

632So, you can see why those energy sources are highly desirable from the point of heading off climate change. Let’s summarize again.Each $1000 of production requires a 190 kilograms, or 0.19 tons of oil equivalent of energy. And each one ton of oil equivalent on average is associated with 2.4 tons of CO2 emissions. So let’s do the arithmetic. Expressed in $2,005 used for this illustration, the world economy at 2010 was at about $68 trillion. $68 times 0.19 tons of oil equivalent per $1,000 times 2.4 tons of carbon dioxide per ton of oil equivalent energy turns out to be 31 billion tons of CO2 emission, and viola, that’s what the world released into the atmosphere in 2010 by virtue of its fossil fuel use.

So you see we can measure the size of the economy times the energy use per unit of economy, per $1,000, times the amount of CO2 released per unit of energy. And the result is a very big number, 31 billion tons of carbon dioxide released. We also put CO2 into the atmosphere as humans in other ways. We chop down trees. And when we chop down trees, the carbon that was stored in those trees is released into the atmosphere if the trees are burned or, or decay. And so carbon that was sequestered biologically is released into the atmosphere as well. That adds a few billion tons of carbon dioxide emissions in addition to those caused by fossils fuel use. Little more arithmetic. For every ton of CO2 put into the air, just a bit less than half of that stays in the air, because some of the CO2 dissolves in the ocean, some of it gets sequestered in plants and trees back on Earth. And so, of the one ton that’s put into the air, approximately 0.46 of that or 46% of what’s admitted into the air, stays in the air. And the other 54% typically is stored in what are called natural sinks, the oceans or the land.

Now, that means that if we put 31 billion tons into the air, a little over 14 billion of those tons stayed in the air. Is that a lot, 14 billion tons, for our big atmosphere? Well we can make that calculation.

We can look at the total volume of the atmosphere, how many molecules are there. How many molecules of CO2 have been put up in those tons? You have to get out your chemistry text to do that. And what you find when you do that is that for every 7.8 billion tons of carbon dioxide put into the atmosphere, the concentration of carbon dioxide in the atmosphere rises by one part per million. So that’s the translation factor. To raise the CO2 concentration in the atmosphere, which is filled with nitrogen and oxygen, and many other mole-, types of molecules. To raise the CO2 by one molecule per each million molecules of all kinds in the atmosphere, you have to put into the atmosphere 7.8 billion tons.

So this gives us now a quantitative sense of what we’re doing. If we have put 14.2 billion tons staying in the air, and 7.8 billion tons raises the carbon dioxide concentration by one part per million. Then the amount that we emitted into the atmosphere in 2010 from fossil fuel use, raised the, carbon dioxide concentration by about 1.8 parts per million or, nearly two molecules for every million in the atmosphere were now CO2 it raised in CO2 concentrations.

Is that a lot? Yes.

Is it frightening? Yes.

Let me show you why. We look again, at a graph of the concentration of CO2 in the atmosphere on the planet Earth, over hundreds of thousands of years. And the concentration of CO2 fluctuates for normal process, even putting humanity out of the story, over geologic time these levels of CO2 rise and then fall and then rise and fall as part of the long run carbon dioxide cycle. And that cycle is driven in important part by systematic changes of the earth’s orbit. And if you look at this reconstruction of the carbon dioxide concentration of the atmosphere over the last 800,000 years starting all the way to the left-hand side of the graph, the first peak you see is the carbon dioxide rose to a little bit over 250 parts per million. Then it fell to under 200 parts per million. Then around 700,000 years ago it rose again to nearly 250 parts per million and then it fell again, then it had another peak at 600,000 years ago, and so forth. So you go up and down, up and down, driven by natural changes of the Earth’s orbital cycle, but then as you move to the right that means coming closer and closer to the present on this graph. Suddenly, something really weird happens. Instead of going up down up down up down, it suddenly goes up, up, up, up, up, up, up. Shoot straight up. Just in the last 100 years of this 800,000 year graph. That’s humanity burning fossil fuel. Thank you, James Watt. Great invention. Great idea.

You made possible the world economy, but now look at the situation. CO2 soaring. How high does it go? Far higher than anything we’ve seen on this planet for 800,000 years, indeed for 3 million years. In 2013 it reached 400 parts per million. A CO2 concentration the likes of which we have not seen on the planet Earth for millions and millions of years. What the climate scientists tell us is, that this kind of change is consistent with a significant rise of temperatures on the planet. Indeed if we reach, say 450 parts per million of CO2, we are very likely to be living on a planet that on average is two degrees centigrade warmer than before the industrial revolution. Now two degrees centigrade might not sound like much, but it implies even larger increases of temperature in the higher latitudes and it implies massive changes of the Earth’s climate, of rainfall, of droughts, of floods, of sea level increase. So we’re talking about changes in CO2 concentrations that when translated into global warming, and into climate change more generally, are extremely large and extremely dangerous and happening now.

How fast are they happening? If we’re at 400 parts per million today, and that’s rising by about two parts per million each year, you can see that to reach 450 is just 25 years from now. My word. We can’t even change it at world energy system at, at that rate. So we’re on a trajectory that is very fast, and very troubling. And, add in to the fact that that’s assuming we stay where we are. Now think about tripling the world economy and tripling the amount of energy used, and if we do it using the same energy mix that we have right now, we’d be increasing CO2 not two parts per million, but five or six parts per million within a few decades. In other words, if we don’t change course we are on a path of extraordinary peril.

Where because of our fossil fuel reliance, we would be seeing mega-droughts, we would be seeing mega-floods, more extreme storms, more species extinction, more crop failures. A massive sea level rise over time, and a massive acidification of the ocean as that CO2 dissolves into the ocean, produces carbonic acid, and reduces the pH of the ocean. We have to change course, and we have to change course quickly. More quickly than the politicians are telling us, by far.

But there’s good news, let me not leave us in despair. We have powerful technologies at sharply falling prices for solar power, for wind power, for energy efficiency, for smarter systems that can economize tremendously on energy and shift us to low carbon means. We’re going to revisit some of those methods very shortly.