Increasing concentrations of greenhouse gases (GHGs) such as CO2 in the atmosphere is a global warming. Human activities are a major cause of increased CO2 concentration in atmosphere, as in recent decade, two-third of greenhouse effect was caused by human activities. Carbon capture and storage (CCS) is a major strategy that can be used to reduce GHGs emission. There are three methods for CCS: pre-combustion capture, oxy-fuel process, and post-combustion capture. Among them, post-combustion capture is the most important one because it offers flexibility and it can be easily added to the operational units. Various technologies are used for CO2 capture, some of them include: absorption, adsorption, cryogenic distillation, and membrane separation. In this paper, various technologies for post-combustion are compared and the best condition for using each technology is identified.

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Carbon Dioxide Separation from Flue Gases: A Technological Review Emphasizing Reduction in Greenhouse Gas Emissions

Progress in carbon capture technologies.

High temperature CO2 sorbents and their application for hydrogen production by sorption enhanced steam reforming process

A viable way to manage the inherently intermittent availability of solar energy in concentrated solar power plants is to store solar energy during on-sun hours to be able to use it later during off-sun hours, enabling on-demand electricity delivery. Thermochemical heat storage systems present some noteworthy advantages when compared with latent and sensible heat storage, namely (i) high energy storage density because the storage capacity by unit of mass or volume corresponding to the reaction enthalpy is generally high, (ii) heat storage at room temperature and long term energy storage because the products can be cooled and stored at room temperature without energy losses as heat can be stored indefinitely in chemical bonds, (iii) facility of transport because solid materials can be transferred over long distances, (iv) constant restitution temperature providing constant heat source because exothermic reactions are carried out at sufficiently high temperatures to generate electricity in constant conditions and therefore to produce a constant power. This paper presents an overview of the different potential thermochemical systems based on reversible solid-gas reactions operating at high temperatures and a screening of suitable materials that are interesting candidates in the 400–1200 °C range for thermochemical heat storage in concentrated solar power systems. The most promising materials belonging to the metal oxides, hydroxides, and carbonates solid-gas systems are selected for experimental validation and further investigations.

Screening of thermochemical systems based on solid-gas reversible reactions for high temperature solar thermal energy storage

Hydrogen production from thermochemical conversion has been considered the most promising technology for the use of biomass, and some novel methods are also being developed for low cost and high efficiency. This review presents the recent progress in the studies on hydrogen production from different kinds of biomass by pyrolysis, gasification and steam reforming without and/or with chemical-looping technologies. Considering potential applications, the Ni-based catalysts made of cheap and earth-abundant elements are especially important for the economically viable hydrogen production from biomass by thermochemical conversion, and can also effectively be compensated for and modified, to some extent, by using extremely low noble metal loading for retaining high catalytic activity, high coke resistance and long-term stability. The catalyst modification strategies of adding other metals, minimizing Ni particle sizes and improving the supports are highlighted. The sorption-enhanced steam reforming (SESR) and chemical looping steam reforming (SE-CLSR) processes with in situ CO2 removal using different reactors have been considered to change the normal equilibrium limits of the water–gas shift (WGS) reaction, and thus increase feedstock conversion and process performances. The auto-thermal operating conditions and CO2 capture during hydrogen production can be achieved by chemical looping processes with cyclic oxidation–reduction of oxygen carriers (OCs). This paper discusses the related issues, challenges and prospects, along with the possible solutions in order to help in the development of efficient hydrogen production from the thermochemical conversion of biomass.

Hydrogen production from the thermochemical conversion of biomass: issues and challenges

High temperature CO2 capture using calcium oxide sorbent in a fixed-bed reactor.

The invention belongs to the technical field of biomass energy chemical industry and relates to a process for producing hydrogen by continuously catalyzing, absorbing, strengthening and reforming biological glycerine through a moving bed. The process is characterized in that: the biological glycerine is firstly evaporated in an evaporator, is mixed with water vapor and nitrogen to be fed into a reformer, and is in countercurrent contact with a catalyst and adsorbent particles to react; the catalyst and the adsorbent after the reaction drop into a regenerator to be regenerated; the catalyst and the adsorbent are continuously moved, reacted and regenerated between the reformer and the regenerator through a lifting tube; and the fresh catalyst and the adsorbent needing to be supplemented can be fed into the reformer through a supplement inlet. The process can prepare a high-purity hydrogen product from the biological glycerine raw material at the temperature of between 450 and 600 DEG C, and realizes continuous movement, reaction and regenerative circulation of the catalyst and the adsorbent so that the catalyst and the adsorbent always run in a nearly fresh state. The process greatly improves the purity of the hydrogen product, reduces the separating cost of the hydrogen producing product and has certain significance to hydrogen production and control of CO2 discharge.

Yingguang Liu

Papers

High temperature CO2 capture using calcium oxide sorbent in a fixed-bed reactor.

Process for producing hydrogen by continuously catalyzing, absorbing, strengthening and reforming biological glycerine through moving bed