An Economy Based on Carbon Dioxide and Water

This chapter makes the analysis of the possible routes for large scale CO₂ utilization (CCU). Processes that convert CO₂ into chemicals, materials and fuels are discussed, as they are part of the strategy for reducing the CO₂ emission into the atmosphere. Technical uses of CO₂, which do not imply its chemical conversion, are discussed in Chap. 3, while mineralization and carbonation reactions for the production of inorganic materials are treated in Chap. 4. Here, the catalytic synthesis of organic products with a market close to, or higher than, 1 Mt/year is discussed, presenting the state of the art and barriers to full exploitation. Minor applications are summarized, without a detailed analysis as their contribution to CO₂ reduction is low, even if they can favour the development of a sustainable chemical industry with reduction of the environmental impact. Energy products (C1 and Cn molecules) are discussed for some peculiar aspects in this chapter, as their catalytic production will be extensively presented in following chapters where the potential of using CO₂ and water as source of fuels is analysed for its many possible applications setting actual limits and future perspectives. A comparison of Carbon Capture and Storage-CCS and CCU is made, highlighting the pros and cons of each technology.

As the rapid rise of the atmospheric CO₂ concentration has aroused increasing concern worldwide on the global climate change, the research activities in CO₂ capture both from the concentrated CO₂ sources and the atmosphere have grown significantly. The amine based solid sorbents exhibited great promise in the near-future application for CO₂ capture owing to their advantages including high CO₂ capacity even at extremely low CO₂ concentration (e.g., 400 ppm), excellent CO₂ sorption selectivity, no need for moisture pre-removal (moisture even shows promotion effect), lower energy consumption, less corrosion and easy handling compared to liquid amine. Among them, PEI-based sorbents have been considered as one of most promising candidates and have been extensively studied. Great progress has been made in the past two decades. Hence, in this review, we summarize the recent advances with supported PEI sorbents for CO₂ capture, with an emphasis on (1) sorbent material development including the effects of support and polymer structure; (2) CO₂ sorption mechanism; (3) CO₂ sorption kinetics, (4) sorbent deactivation, and (5) practical implementation of PEI-based sorbent materials. At last, the remaining problems and challenges that need to be addressed to improve the competitiveness of sorbent-based capture technologies are discussed. Through the current review, we expect it will not only offer a summary on the recent progress on the supported PEI sorbents, but also provide possible links between fundamental studies and practical applications.

These last decades, carbon dioxide emissions have drawn a lot of attention because of the greenhouse effect. According to the Kyoto protocol, the 15 European countries committed themselves to reduce their carbon dioxide emissions by an average of 8% with respect to the 1990 level within the period 2008–2012. The more recent Paris Agreement [1] urges all parties to ratify and implement the second commitment period of this Kyoto Protocol up to 2020. In this context, the goal of this chapter is to analyze the technical and industrial applications of carbon dioxide as a possible contribution to CO₂ mitigation by supplanting less environmentally friendly technologies based on chemicals having a higher impact on soil, water and atmosphere. In this Chapter we make a distinction between different approaches on how and where carbon dioxide is being captured and used. The present text is an update of the previously published Chapter “Vansant J, Carbon Dioxide Emission and Merchant Market in the European Union.” In: Aresta M. (eds) Carbon Dioxide Recovery and Utilization, 2003, 3–50, Springer, Dordrecht.

The appeal of mineral carbonation (MC) as a process technology for scalable and long-term CO₂ reduction, is that it is a solution that has the sequestration capacity to match the amount of CO₂ emitted from energy generation and industrial activities [1‐3]. Many inorganic materials such as minerals [4, 5], incineration ash [6, 7], concrete [8, 9] and industrial residues [10, 11] are potentially huge sinks for anthropogenic CO₂ emissions. These materials are typically abundant sources of alkaline and alkaline-earth metal oxides, which can react naturally with CO₂ to form inorganic carbonates and bicarbonates. In addition, their products are thermodynamically stable and relatively inert at ambient conditions. On paper, MC should be able to fully sequester all anthropogenic CO₂ emissions, since the abundance of magnesium and calcium atoms on Earth far exceeds the total amount of carbon atoms [12, 13]. However, despite the apparently favorable pre-conditions, we still observe a net accumulation of CO₂ in the atmosphere because the rates of reaction to form (bi)carbonates in nature are too slow compared to the current rate at which CO₂ is being emitted [14, 15]. If left to their own devices, thousands of years are needed to achieve any substantial sequestration of CO₂ [16]. This is clearly not rapid enough to solve the pressing problem of climate change that is already affecting us now. Therefore there is a need to employ mineral carbonation as an artificial method to accelerate the rates of CO₂ sequestration. In this chapter, we will take a look into the chemistry and thermodynamics of mineral carbonation and discuss some of the main obstacles to large scale MC implementation. Additionally, we highlight the types of starting materials from which basic alkaline-earth metal oxides can be obtained and discuss how their abundance and properties affect MC performance. We will also give a short review of current research in the area to develop MC into viable and economic processes, with some focus on the main categories of process designs and their working principles. We will then look at MC from a techno-economic standpoint and assess the opportunities to integrate MC into the existing industrial and environmental landscape. Lastly, we conclude the chapter with a hypothetical scenario of MC deployment in Singapore, an economically developed but land-scarce country under threat by rising sea levels.

Carbon-dioxide emission from various sources is the primary cause of rapid climate change. Its utilization and storage are becoming a pivotal issue to reduce the risk of future devastating effect. The conversion of carbon-dioxide as an abundant and inexpensive feedstock to valuable chemicals is a challenging contemporary issue having multi-facets. There is a need to elucidate the process of utilizing CO₂ to gain a fundamental understanding to overcome the challenges. This chapter focuses on converting CO₂ to C₁ valuable chemicals via hydrogenation (methane, methanol, syngas, formic acid) and reforming reactions (syngas). The first four parts of this chapter cover the production of methane, methanol and formic acid via hydrogenation reaction and syngas via reverse water gas shift reaction. Moreover, the last part of the chapters consists of reforming whereby CO₂ acts as a mild oxidant for the production of syngas (CO + H₂). The chapter covers different aspects, including the current challenges in the process, the state of the art and design of catalysts, and mechanistic consideration, all of which are critically evaluated to give the insight into each reaction.

Catalytic CO₂ conversion to clean fuels and chemicals is crucial for mitigating the climate change and reducing the dependence on nonrenewable energy resources. Converting CO₂ by hydrogenation using heterogeneous catalysts has been extensively studied in the past decades, and the products distribution can be manipulated by selecting catalysts and reaction conditions. Generally, CO₂ conversion to hydrocarbons and to alcohols are the two routes that have been explored the most, and significant advances have been made in developing efficient catalysts and understanding the thermodynamics and kinetics of the two paths. However, effective catalysts and processes are required to selectively maximize CO₂ conversion to either C₂–C₄ olefins, C₅+ hydrocarbons, or aromatics and to minimize CH₄ and CO. Catalysis for higher alcohols synthesis from CO₂ is still in the very early stage and requires more fundamental research due to the lack of understanding the possible reaction pathways and of controlling the key intermediates. This review summarizes the progresses in CO₂ conversion via heterogeneous catalysis for the two pathways in the past five years and discusses the origin of the activity and plausible reaction mechanism through a combination of computational, experimental, and analytical studies, along with suggestions for designing improved catalysts in the future.

This chapter covers the electrochemical and photoelectrochemical conversion of CO₂ in aqueous media. It is divided into sections that consider heterogeneous electrocatalysts on metal electrodes, homogeneous catalysts interacting with metal surfaces, light-driven semiconductor electrodes, and hybrid systems that combine heterogeneous interfaces with surface-confined molecular components.

In this chapter, we will explain why plasma is promising for CO₂ conversion. First, we will give a brief introduction on plasma technology (Sect. 8.1), and highlight its unique feature for CO₂ conversion (Sect. 8.2). Next, we will briefly illustrate the most common types of plasma reactors, explaining why some plasma types exhibit better energy efficiency than others (Sect. 8.3). In Sect. 8.4, we will present the state-of-the-art on plasma-based CO₂ conversion, for pure CO₂ splitting and the combined conversion of CO₂ with either CH₄, H₂O or H₂, for different types of plasma reactors. To put plasma technology in a broader perspective of emerging technologies for CO₂ conversion, we will discuss in Sect. 8.5 its inherent promising characteristics for this application. Finally, in Sect. 8.6 we will summarize the state-of-the-art and the current limitations, and elaborate on future research directions needed to bring plasma-based CO₂ conversion into real application.

Bioelectrosynthesis from CO₂ offers the prospect to reuse CO₂ emissions as a feedstock and generate fuels and value-added chemicals from CO₂ and its derivatives working in water. The technology has environmental advantages due to its sustainability, renewability and environmentally friendly qualities. The future potential of these systems can be associated to the framework of CO₂ biorefineries, the power-to-gas concept, or biogas upgrading, thus helping to step-up in the desired global transition from fossil fuel-based to electricity-based economy.

Microbial fixation of carbon dioxide (CO₂), represented by photosynthesis, is an important link of the global carbon cycle. It provides the majority of organic chemicals and energy for human consumption. With the great development and application of fossil resources in recent years, more and more CO₂ has been released into the atmosphere, and the greenhouse effect is looming. Therefore, more efficient carbon fixation processes are urgently needed. In view of this, the microbial conversion of exhaust CO₂ into valuable fuels and chemicals based on an efficient CO₂ fixation pathway is very promising. With the rapid development of systems biology, more and more insights into the natural carbon fixation processes have become available. Many attempts have been made to enhance the biological fixation of CO₂, by engineering the key carbon fixation enzymes, introducing natural carbon fixation pathways into heterotrophs, redesigning novel carbon fixation pathways, and even developing novel energy supply patterns. In this review, we summarize the great achievements made in recent years, and discuss the main challenges as well as future perspectives on the biological fixation of CO₂.

Biomass, either terrestrial or aquatic, can efficiently fix CO₂ from a variety of sources, such as the atmosphere, power plant and industrial exhaust gases, and soluble (hydrogen)carbonate salts thanks to the enzyme Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). In addition to the carboxylation of ribulose that fixes CO₂ into glucose (ca. 60%), used by the biomass as a source of energy and for building cellulose, RuBisCO also oxidizes the substrate (ca. 40%). Attempts have been made to engineer the enzyme for an enhanced carboxylation. Besides, efficient light-using organisms are under deep investigation. In particular, enhanced bio-fixation using microalgae has recently become an attractive approach to CO₂ capture and C-recycling with a benefit derived from downstream utilization and application of the resulting microalgal biomass. This is a paradigmatic example of use of water and CO₂ for stepping from the linear- to the circular-C-economy. It is of importance to select appropriate microalgal species that have a high growth rate, high CO₂ fixation ability into valuable components, resistance to contaminants, low operation cost, and are easy to harvest and process. Strategies for the enhanced production of bioproducts and biofuels from microalgae, based on the manipulation of the strain physiology by controlling light, nutrient and other environmental conditions, which determine an efficient carbon conversion, are underway since long time. They are discussed in this Chapter together with an assessment of the value of the algal strain P. Tricornutum.

Mere improvements in energy efficiency and development of alternative energy sources may not be sufficient and timely to reverse the continuing rise of the CO₂ emissions before it crosses dangerous levels. Given the mixed feelings on the geological sequestration of captured CO₂ and the scale of worldwide CO₂ emissions, the idea of utilizing CO₂ to produce fuels and chemicals is receiving increasing attention as a potential long-term solution to this problem. The source of hydrogen is vital for producing fuels and chemicals from CO₂. We consider both renewable (i.e., solar) and nonrenewable (i.e., fossil fuels) sources of hydrogen and identify several fuels and chemicals that can be produced from CO₂ while meeting the hard constraint of net zero CO₂ emission. Taking a small, geologically disadvantaged, and developed city-state of Singapore as an example, we analyze and compare thermodynamically feasible production of fuels/chemicals, whose global demands can make a significant dent in CO₂ emissions. We also identify the hydrogen source and the cost at which it will make economic sense under various carbon tax regimes.

CCU is a step towards a Cyclic Carbon Economy, with different effects over diverse time-scale. In this chapter, the potential benefits of CCU are summarized with a perspective look on the amount of used/avoided CO₂ in the short, medium, long term and on the conditions that must be fulfilled for an extensive utilization of such abundant source of carbon.