The Deep Decarbonization of Energy Systems IV

Global Mitigation Scenario

In the previous chapter, I introduced the three pillars of the deep decarbonization of our energy system. So let me just very quickly recap what they are.

  • First, the energy efficiency and conservation measures.
  • Second, the production of low carbon electricity.
  • And third the fuel switching from high carbon to low carbon energy carriers.

537As I said, these three pillars represent the overarching framework for these deep decarbonization strategies of our energy system. But before we conclude this lecture, there are still two questions that we need to answer.

  • The first is how do these pillars apply to the different sectors of the economy and how can the coordinated implementation of these three strategies result in the overall deep Decarbonization of the economy?
  • The second question is very importantly, the quantification of their effect by how much do each sector emissions need to be reduced to reach level of deep decarbonization consistent with the objective of limiting the increase in mean surface temperature below 2-degree Celsius?

To answer these two questions we’re going to use the results of a global modeling scenario. The graph in the top left corner represents the business-as-usual scenario, or the continuation of the current trends. This is if you will, the scenario if we don’t implement climate change mitigation policies which by the way, means that this is a scenario in which we don’t avoid dangerous climate change and we would face the catastrophic consequences from an uncontrolled climate change. As you can see on this graph, on the top left corner, CO2 energy emissions are increasing sharply. They go from approximately 35 gigaton of CO2 energy emissions by 2015 to more than 50 gigaton of CO2 energy by 2050. And in this scenario, in this business-as-usual scenario, emissions from all sectors are rising, but in particular, the emissions from power generation.541

To the country the graph in the top right-hand corner represents a 2-degree Celsius scenario. So in, in this scenario the CO2 emissions are reduced over time to a level that is consistent with the objective of staying within 2-degree of global warming. And as you can see on this graph, on the top right-hand corner emissions peak by approximately 2020 and then they’re reduced, they’re in fact reduced dramatically to approximately 11 gigaton of CO2 energy by 2050. So what do we really learn from the results of this global mitigation scenario? Well it shows a few important things.

  1. First it shows that staying within the 2-degree limit requires deep emission reductions in all sectors of the economy. Profound emission reductions in power generation, industry, transport and buildings. But what is interesting is that it shows also that these sectoral emissions, the emissions from the different sectors are reduced in different proportions. And that is due mainly to two factors.
    1. I mean first, the fact that the different sectors do not have the same technical mitigation potential. So technically not the same options to reduce their emissions,
    2. but also that the cost of these different options in the different sectors is different.

And on the two graphs at the bottom, you can see the amount of the emissions reductions by sector in the 2-degree scenario compared to the reference scenario. And I’m just showing you one example here.

542But I want to stress what is really a general result of all global mitigation scenarios that limit the rise in temperature below 2-degree Celsius and it is that emissions from the power generation are reduced frankly to almost zero in these scenarios. And electricity production by 2050 is almost completely decarbonized and because power generation is done by using zero or very low sources of energy such as renewable energy, hydro, solar, wind, geothermal, that’s renewable energies. Or on the other hand, nuclear power or fossil fuel plus carbon capture and sequestration. This is a very important result, because the power generation in 2-degree Celsius scenarios goes from being the major source of CO2 energy emissions today to being almost completely decarbonized. So producing virtually zero CO2 energy emissions by 2050.

  1. Another result going beyond power generation is of course that the emission reductions in the other sectors, so in building, industry and transport are also very substantial. So I don’t want to pretend like this is only an agenda for the power sector. This is certainly not the case. The power sector needs to be at the front and center of the deep Decarbonization of energy system, that is for sure, but the energy end use sectors also need to see their emissions decreasing very significantly and very quickly. For example, in the order of 40% for the transport sector in 2050 and 70% for the industry and building sectors in this scenario.

There are two things I would like to say to conclude this lecture.

The first is that this global mitigation scenario as all the others, again, I picked one example, but all the conclusions can be applied to all the scenarios. This global mitigation scenario consistent with the 2-degree limit rests on the deployment of technologies that are not yet technologically mature, or that are still far too costly to achieve deep decarbonization. Examples of these technologies include carbon capture and sequestration, or nuclear force generation, or smart grids and energy storage to be able to operate the power system with high shares of intermittent. That is, intrinsically time variable renewable energy such as wind power or solar power. It is clear that these technologies will need further research, development and demonstration before they can be deployed at scale and at reasonable costs.

The second thing I want to mention is that I presented you the results of a global mitigation scenario. But as we’re going to see, country specific deep decarbonization strategies show a very wide variety of different approaches based on different national circumstances.

543These different circumstances includes things like different socioeconomic conditions or different natural resources endowments such as, well different availability of renewable energy potential, or different potential for carbon sequestration sites, or also, and it’s very important to take that into account, different national preferences regarding the different technologies, nuclear or CCS or other technologies. But in the next lectures we will look in further detail at these two questions.

  • First, the key technological challenges that must be met to achieve deep Decarbonization and we will discuss each of them in detail,
  • and second, we will be looking at country-specific case studies to see really concretely how deep decarbonization can be achieved within very different national contexts.

The Deep Decarbonization of Energy Systems III

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.


The Deep Decarbonization of Energy Systems II

Energy-Related CO2 Emissions Trends

In this chapter I want us to take a closer look at the current energy trends. I want us to take a closer look at the current dynamics in the energy markets because to see eventually how we can decarbonize the energy systems, we first need to really well understand what is going on today and how we can reverse the current trends.

So where are we? As you can see on these pie charts, in 2010, primary energy was approximately 13 billion tons of oil.521

And final energy consumption, 9 billion tons of oil equivalent. I am using the unit of billion tons of oil equivalent to be able to measure within a single unit all the different sources of primary energy I mentioned in the previous chapter. By the way, exactly in the same way, we used the unit of CO2 equivalent to measure with a single unit all sources of greenhouse gases.

As you can see on the pie charts, oil is the biggest source of primary energy, 32%. Even before coal, which represents 27% of the primary energy and gas with 21% of the total. So fossil fuels really are and by far, the major sources of primary energy today. And this is precisely where the problem lies.

Final energy is primarily consumed through oil, again. This time for a 41% of the total.

Then electricity for 18%, then gas, 15%, and coal for 10%. But let’s look in further detail in which sectors and for which purposes the different sources of energy are used, because there are some important differences across the different sectors.522

As you can see on these other pie charts, coal as a primary source of energy is mainly used in the industry sector, 80%. Some of the most energy intensive industries include cement, steel, or the mining sector for example.

Oil for its part is mainly used in the transport sector, 60% of the total energy consumption of the transport sector. Oil is used in particular in different forms, but in the internal combustion engine of private vehicles and trucks, but is also used for air transport and ocean shipping. Gas a fuel is mainly used in the residential and commercial building sector, most importantly for heating purposes.

That’s 46% of the total. But also gas is used in industry, for 35% of the total. And finally, electricity is used primarily in the residential and commercial building sector for 57%, to provide lighting for example, or electric heating or to power all different sorts of electrical equipment. But it is also used, electricity is also used in industry.

An example of industry that is very electricity-intensive, that consumes a lot of electricity per unit of output is the aluminum industry. In the recent past and in spite of the repeated commitments to reduce greenhouse gases emissions that we discussed in the previous lectures, the energy consumption and the CO2 energy emissions have continued to rise. And in fact, they have continued to rise very sharply. The CO2 energy emissions increased by 10% during the 1990 to 2000 period.523

And they even increased by 30% during the last ten years from the year 2000 to 2010. And as you can see on the graph, the rise in CO2 energy emissions was especially strong in China. Also in India. Although the Indians’ emissions are of course still much lower than the Chinese emissions. In the U.S. the emissions increased from 1990 to 2000, but they decreased from 2000 to 2010, in part due to a shift from coal to gas in the power supply. In the European Union the emissions fell steadily from 1990 to 2010 due in part to the implementation of climate change mitigation policies but also and a bit more unfortunately, more recently as a result of the economic crisis.

And the emissions as you can see on the graph fell very sharply in Russia from 1990 to 2000, mostly as a result of the collapse uh, of the Soviet Union, that the emissions are more or less flat in Russia since the year 2000. If the growth in CO2 energy emissions during the 2000-2010 period was so fast, it’s because energy demand rose very quickly in this period, mainly due to the rapid economic catch-up growth in some of the world emerging countries. But it’s not the entire story.

The CO2 energy emissions rose very quickly, also because the carbon content of energy consumption increased which is a very bad news from a climate change mitigation perspective. In fact, almost half of the incremental energy consumption in the last ten years during the 2000 to 2010 period came from coal as you can see on the graph. This is absolutely gigantic and even more than during the previous decades.524

So instead of decarbonizing our energy systems, we are currently carbonizing them. The current energy trends are therefore completely out of line with the objective of avoiding dangerous climate change.

In fact, they lead straight to catastrophic climate change because they would induce a rise in the mean surface temperature by 4-degrees Celsius or perhaps even 6-degree Celsius. So the current trend is a trend of very rapidly rising energy consumption and increasing CO2 content of energy when we should instead be further de-coupling energy consumption growth from GDP growth and decreasing the carbon content of energy by relying much more heavily on the low or even zero carbon sources of energy. In the next chapter we’re going to see how this can be achieved.

The Deep Decarbonization of Energy Systems I

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.