Biomass combustion with CO2 capture by chemical looping
| Autor: | Abad Secades, Alberto, García Labiano, Francisco, Mendiara, Teresa, Diego Poza, Luis F. de, Pérez-Astray, Antón, Izquierdo Pantoja, María Teresa, Gayán Sanz, Pilar, Adánez Elorza, Juan |
|---|---|
| Přispěvatelé: | Abad Secades, Alberto [0000-0002-4995-3473], García Labiano, Francisco [0000-0002-5857-0976], Mendiara, Teresa [0000-0002-0042-4036], Diego Poza, Luis F. de [0000-0002-4106-3441], Izquierdo Pantoja, María Teresa [0000-0002-2408-2528], Gayán Sanz, Pilar [0000-0002-6584-5878], Adánez Elorza, Juan [0000-0002-6287-098X], Abad Secades, Alberto, García Labiano, Francisco, Mendiara, Teresa, Diego Poza, Luis F. de, Izquierdo Pantoja, María Teresa, Gayán Sanz, Pilar, Adánez Elorza, Juan |
| Rok vydání: | 2017 |
| Předmět: | |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| Popis: | 2 figures.-- Work presented at the 7th International Congress on Biofuels and Bioenergy, October 02-04, 2017 Toronto, Canada Bioenergy and Carbon Capture and Storage (BECCS), is an interesting option to remove CO2 from the atmosphere, thus mitigating the CO2 emissions from the use of non-renewable sources, i.e., fossil fuels. BECCS has been identified as a relevant measure to achieve the target enforced by the United Nations Framework Convention on Climate Change (UNFCCC) in the Paris Agreement: To limit the increase in the average world temperature to 2ºC above pre-industrial levels. However, implementing CO2 capture in bioenergy through common technologies has the drawback of high economic and energetic costs. In this sense, the Chemical Looping Combustion (CLC) technology allows inherent CO2 capture at low cost during combustion. The benefits of CLC are based on avoiding the costly separation steps required in commercial CO2 capture processes, e.g., CO2 separation in flue gases or O2 production for oxy-fuel combustion, by the use of an oxygen carrier. The purpose of the oxygen carrier, usually a particulate metal oxide, is to transfer oxygen from air to fuel in order to avoid the direct contact between them. Thus, the oxygen carrier provides the oxygen required for combustion in the so-called fuel reactor. The oxygen carrier is later regenerated by air in the air reactor. The most common design of a CLC unit includes two fluidized bed reactors, being those mentioned fuel and air reactors with the oxygen carrier continuously circulating among them. CLC has been widely investigated for the use of gaseous fuels and coal but the interest of using biomass has recently increased considering that negative CO2 emissions would be possible. The objective of this work is to contribute to the development of biomass combustion by CLC evaluating the use of new and highly reactive Mn-based materials as oxygen carriers. Experiments were performed in a continuous 500 Wth CLC unit at Instituto de Carboquimica (ICB-CSIC), consisting of two interconnected fluidized-bed reactors. After determination of both gas streams composition, the performance of the CLC process was assessed by calculating the CO2 capture rate and the combustion efficiency as a function of the operating conditions. During the experimental campaign, the temperature in fuel reactor and the circulation rate of the oxygen carrier were varied. In general, CO2 capture rates close to 100% were obtained, which increased with temperature. In addition, high values of combustion efficiency were obtained. When the combustion was incomplete, the major unburnt compounds from the fuel reactor were H2, CO and CH4. Likely, these unburnt gases could proceed from the volatile matter as a high conversion of char would be expected. Interestingly, the amount of tar detected was low and they do not contribute significantly to the combustion efficiency. This work presents an overview of the recent advances in bio-CLC technology within the key strategies arising nowadays to mitigate climate change. The Paris Agreement, the new treaty of the United Nations Framework Convention on Climate Change (UNFCCC), urges to decarbonize the world energy systems in the near future in order to limit the increase in the average world temperature to 2ºC above pre-industrial levels. To reach this goal, CO2 emissions should start to decrease by 2020 and become negative by the end of the century. Among the different options, most of the low-carbon scenarios rely on the use of BECCS (Bioenergy and Carbon Capture and Storage) as mandatory technologies to reach negative emissions. In this sense, Chemical Looping Combustion (CLC) is considered one of the most promising CCS technologies for power plants and industries because its inherent CO2 capture avoids the energetic penalty present in other competing technologies. CLC process is based on the use of a solid oxygen carrier to transfer the oxygen from air to the fuel avoiding direct contact between them. The technology has undergone a great development during last 15 years including operational experience in continuous units and oxygen carrier’s manufacture. In addition, the new Chemical Looping with Oxygen Uncoupling (CLOU) process represents a qualitative step forward in solid fuel combustion due to the use of materials with capability to release oxygen. There are several renewable energy sources that can be used in chemical looping processes, including both solid and liquid fuels. The use of biomass in CLC represents important advantages compared to conventional biomass combustion. Besides CO2 negative balance, higher thermal efficiency, NOx formation reduction and lower corrosion in heat exchangers have been reported. In addition, several renewable liquid fuels, such as bioethanol can be also used both in combustion (CLC) and reforming (CLR) processes for heat/electricity and syngas/H2 production, respectively. In summary, the use of renewable fuels in chemical looping processes represents at this moment a very promising opportunity for future green energy development. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|