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.

As 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.

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.

But 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.

2. 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.

These 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.

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