Recent Advances on CO2 Mitigation Technologies: On the Role of Hydrogenation Route via Green H2

Abstract

The increasing trend in global energy demand has led to an extensive use of fossil fuels and subsequently in a marked increase in atmospheric CO2 content, which is the main culprit for the greenhouse effect. In order to successfully reverse this trend, many schemes for CO2 mitigation have been proposed, taking into consideration that large-scale decarbonization is still infeasible. At the same time, the projected increase in the share of variable renewables in the future energy mix will necessitate large-scale curtailment of excess energy. Collectively, the above crucial problems can be addressed by the general scheme of CO2 hydrogenation. This refers to the conversion of both captured CO2 and green H2 produced by RES-powered water electrolysis for the production of added-value chemicals and fuels, which are a great alternative to CO2 sequestration and the use of green H2 as a standalone fuel. Indeed, direct utilization of both CO2 and H2 via CO2 hydrogenation offers, on the one hand, the advantage of CO2 valorization instead of its permanent storage, and the direct transformation of otherwise curtailed excess electricity to stable and reliable carriers such as methane and methanol on the other, thereby bypassing the inherent complexities associated with the transformation towards a H2-based economy. In light of the above, herein an overview of the two main CO2 abatement schemes, Carbon Capture and Storage (CCS) and Carbon Capture and Utilization (CCU), is firstly presented, focusing on the route of CO2 hydrogenation by green electrolytic hydrogen. Next, the integration of large-scale RES-based H2 production with CO2 capture units on-site industrial point sources for the production of added-value chemicals and energy carriers is contextualized and highlighted. In this regard, a specific reference is made to the so-called Power-to-X schemes, exemplified by the production of synthetic natural gas via the Power-to-Gas route. Lastly, several outlooks towards the future of CO2 hydrogenation are presented.

The Potential of Algae in the Nutricosmetic Sector

“…During dark respiration, they manage biomass decrease, using lower organic substrate amounts than heterotrophic growth and enhancing the synthesis of the PUFA (polyunsaturated fatty acids) [ 44 , 45 , 46 ]. Algae can improve air quality by fixing CO 2 [ 47 ] (they are responsible for 50% of the photosynthesis on earth) [ 48 ] and are an alternative source of bioenergy production since they produce biofuels [ 49 ]. Finally, they can reduce pollution [ 50 ] by converting water and CO 2 into organic matter [ 51 ].…”

Recent Advances on Fine-Tuning Engineering Strategies of CeO2-Based Nanostructured Catalysts Exemplified by CO2 Hydrogenation Processes

“…The methanation of CO 2 via H 2 , also called the Sabatier reaction (Equation ( 11)), was discovered by the French chemists Paul Sabatier and Jean-Baptiste Senderens at the start of the 20th century and was applied industrially mainly to remove traces of CO x from the H 2 -rich stream in ammonia plants. Later, the reaction was further investigated for the production of synthetic natural gas (SNG) in the 1970s oil crisis [215][216][217]. In the last decades, however, CO 2 methanation has again been in the spotlight, this time being the core reaction in the so-called power-to-gas scheme (alternatively termed as power-to-methane), which involves the mass production of hydrogen via RES-powered water electrolysis and the large-scale capture of CO 2 from the flue gases of hard-to-abate sectors such as cement industries or power plants (Figure 26).…”

Prospects of Solar Driven -Water Electrolysis for Hydrogen Production in South Africa: A Mini-Review

“…The production of hydrogen presents a widely available energy source to replace fossil fuels in transportation, industrial, residential, and commercial sectors. Thus, an economy based on hydrogen has a prospective solution to environmental issues, natural resource depletion, and socioeconomic demands of population growth [2,12]. Also, the production, transportation, storage, conversion, and usage of hydrogen for all fundamental aspects of the economy has a formidable advantage over the fossil fuel economy.…”

“…On the path to a sustainable future, energy security and climate change mitigation represent two of the most pressing challenges [1]. Notwithstanding, the high demand for carbonbased fuels (fossil, coal, natural gas, and oil) pose an unfavourable risk to human health and the environment with greenhouse (GHG) gas emission [2,3]. Of interest, carbonbased fuels provide 85% of global energy needs and emit about 36 billion tons of CO 2 annually [4].…”