Arquivo de etiquetas: CC&S

The Key Technological Challenges of Deep Decarbonization III

Carbon Capture & Sequestration

Here we’re going to discuss about carbon capture and sequestration. So what is it, what kind of a technology is that? It looks almost frightening. So carbon capture and sequestration or CCS, I’m going to use the acronym a lot because otherwise it’s too long, is the capture of CO2 at large stationary point sources such as coal or gas fired power plants, oil refineries, cement plants, or steel mills.

625What are the common characteristics between these different types of activities? It is that they emit exhaust gases with a relatively high concentration of CO2. And it’s an important aspect of where CCS could be feasible.

We need to have somehow a pretty high concentration of CO2 within the entire exhaust gases to be able to operate the CCS technology. That being said, there are broadly speaking, I mean of course there are many more than that, but broadly speaking there are two different types of CCS technologies. What is called pre-combustion CCS technology and post-combustion CCS technologies.

So very simply with post-combustion technologies the CO2 is captured after combustion through a chemical process that separates CO2 from the other gases. Whereas for the pre-combustion technologies the CO2 is removed from the fuels themselves through other chemical processes, but this time as the name obviously indicates, before combustion. So that’s for the capture part of carbon capture and sequestration, CCS. But what happens after that, what do we do with the CO2, because it cannot simply remain in the air once we have separated it through one of these two different techniques?632

Well after the CO2 would be captured at the point source, it would be transported by pipeline to an appropriate geological site for storage under the ground. So what does that mean? I mean what could be considered as an appropriate geological site? I mean what are the conditions that must be met by these sites to safely sequester the CO2 under the ground for a very long period of time? Well as you can see on the picture in front of you there are broadly speaking again, there are more than that, but broadly speaking, three main different options for the geological sequestration of CO2.

  • The first is that what is called mineable coal beds, so it’s a fancy term to speak about the coal veins that cannot be mined.
  • The second type is the depleted oil or gas reserves.

So very simply the empty oil and gas fields, ones that have been exploited where you could put the CO2 back in. And the third and in fact the most important because the scale of these third categories is potentially much higher than the other two, the third type is what we call the deep saline aquifers. So types of geological grounds that are found deep under the earth’s surface.

633So that was for a very general description of the different steps in the process of carbon, capture, we should add, transportation and sequestration of this CCS. So where are we in the process of developing this technology? Well CCS has not yet been proved as a whole system at a large scale. But all the individual components of CCS, so the capture, the transport, the sequestration, all of them are pretty well established technologies and they have been tested in demonstration projects. And to date there are approximately 12 CCS projects that operate under the globe at stationary point sources and most of them are projects on natural gas processing plants while some others are on fertilizer production plants.

So what is really the challenge going forward? I mean what are the obstacles that would need to be overcome if carbon capture and sequestration was to become a real option that could be deployed at scale in many countries? Well there are serious challenges, different types of challenges.  One is costs. The other is scale. And finally there is an issue, an unresolved issue so far regarding the verification that carbon is really sequestered under the ground.

  • So the first open question, what is the optimal power plant design to facilitate carbon capture at relatively low costs?
  • Second open question, what is the best choice of geological sites for the storage of CO2 potentially at a very large scale? I mean we might be talking about tens or hundreds of billions of tons of CO2 to be sequestered during the coming decades. So where is the geological potential for that? I mean which sites would we select to do that?
  • Third open question, what is the design of a reliable and economic hope infrastructure for the transport of CO2?
  • And if you want a fourth question, what are the mechanisms for insuring that the CO2 that is stored remains permanently out of the atmosphere, a very important question indeed, because it determines the success of CCS eventually.

So these are important questions. There are of course other questions. All of them need good answers. But given the importance of carbon and capture and sequestration in many of the deep decarbonization scenarios, including the ones

634I’m going to present when I discuss the results of the deep decarbonization pathway project, given the importance of this technology in so many of these scenarios there is really an urgent need to scale up the research, the development and the demonstration of CCS to test if it can be deployed at scale, if it can be deployed at, at scale safely.

And if it can be deployed at scale at acceptable costs, because the truth is that being able to rely on the large-scale deployment of CCS would greatly facilitate the deep Decarbonization efforts, given what we stressed many, many times now and it is the obvious very heavy dependence of the energy systems on fossil fuels today.

The Key Technological Challenges of Deep Decarbonization IV

Advanced Nuclear Power

Here we’re going to discuss about the new generation of nuclear power reactors.

Today there are approximately 40 countries with nuclear energy as part of their power mix. Countries in very different situations. Some of these countries are proposing to phase out their nuclear power fleet. This is the case for example in Germany. Germany will have no more nuclear power plants in 2023. Other countries are planning to scale back, such as France. France has decided to reduce their share of nuclear energy and its electricity consumption from 75% today to 50% by 2025. But other countries are planning to expand and sometimes dramatically their nuclear capacity. This is the case for example in China. China intends to build the equivalent of the entire existing French nuclear power fleet in the coming years.

641There are, to be frank, serious obstacles standing in the way of the larger scale deployment of nuclear energy worldwide. And the demand to be looked carefully and to be seriously taken into account. Issues of public resistance, in particular, especially following the Fukushima nuclear accident in Japan.

But also more generally speaking and unrelated to a particular event, concerns over the safety of the operation of nuclear reactors. Anxiety about the risk of proliferation. And worries about the issues of waste management. And also I should add, concerns over the costs of nuclear energy because grading the existing nuclear reactors or building new reactors to improve their safety following the recommendations that were made after the Fukushima accident will most likely increase their costs and probably quite significantly.

So it’s also important to recognize that the public support for a nuclear technology as important known technical dimensions that are therefore not easily addressed by engineering improvements.

Different societies have different attitudes towards nuclear energy because they have different histories; they have different cultures, different belief systems. But also because the management of the inherent risks of nuclear energy require the existence of an independent safety agency. And the truth is that the conditions of the independence of this safety agency are not really met in all countries.

That being said, the technical advances can play a critical role in the improvement of the nuclear reactors. And they will be needed in order for nuclear energy to remain a significant part of the power mix in some countries or even potentially to play a growing role and an important role given the need to produce low or zero carbon electricity to avoid dangerous climate change. What are these potential critical technical advances?

Well there are plenty of them, such as breakthrough in the safety systems, advances in fuel security, options for a fuel recyclingor techniques to reduce the costs. All of that will be needed if nuclear energy is to play an important and growing role in the future.

The development of a fourth generation of nuclear reactors offers the prospect of addressing some of these important issues. So what is it, a fourth generation of nuclear reactors? What were the three first generations anyway? We use the term, fourth generation nuclear power to bring together different kinds of advanced nuclear fission energy technology that share a number of key characteristics.

  • The first is the modularity of the production systems and the building of smaller scale units.
  • The second is the use of alternative systems for fuel repossessing or the use of alternative fuels to uranium such thorium.
  • And the third is the design of improved automatic and even passive safety systems.

And I’ll explain in a minute what that is because it’s one of the potentially most important breakthroughs of nuclear reactors in the future. What are the objectives of this fourth generation of nuclear reactors? I mean why do that, why build them differently from the previous generations? Well a number of reason.642

The first is that we’re trying to make the nuclear reactors more simple so that the reactors are less vulnerable to construction delays and cost overruns, which sometimes have been very significant in the past and still are today.

But also objective to address the proliferation concerns, a very serious concern. By making it much more difficult to divert materials for nuclear weapons at any point in the fuel cycle. And some of the fourth generation nuclear reactors address this point. But also and as I said, very importantly, almost the driving force of this fourth generation of nuclear reactors, the objective is to improve safety.

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And in particular, through the use of passive safety systems. So what is it? Well it means that the reactor core would be assured by physical principles to be safe from the meltdown, even in the absence of active cooling. So that’s why we call it passive safety systems. So as you can see, this fourth generation of nuclear reactors offers interesting prospects. The prospect of significant improvements to the existing nuclear reactors, but they still require a high level of research and development and also demonstration before they could be eventually deployed and play a role in the deep decarbonization strategies