Based on the perspective of global environment issues and the
availability of energy, biomass is considered as the ideal energy
for gradually replacing the depleting fossil fuels [1–2]. Among
the biomass utilization technologies, biomass gasification is an
effective and attractive method for converting biomass into syngas
[3–5]. The syngas, a mixture of carbon monoxide and hydrogen,
can serve as an indispensable raw material in chemical industries,
such as the ammonia and methanol manufacturing industries.
Therefore, biomass gasification for converting biomass into syngas
has increasingly aroused general concern. Traditional biomass
gasifiers have been designed in various configurations, such as
fixed bed, fluidized bed and entrained bed [6–9]. However, a large
amount of pure oxygen is required as gasifying agent for traditional
biomass gasification technologies. The introduction of air
separation unit (ASU) would increase the cost and make the facilities
complicated. In addition, biomass gasification and combustion
take place in a reactor, resulting in the low syngas content with
high CO2 emission during the gasification process.
Chemical Looping Combustion (CLC), emerging as a promising
technology with CO2 inherent separation at low cost, has arisen
during last years [10,11]. Generally, a CLC system involves two
interconnected fluidized bed reactors, i.e. air reactor and fuel reactor.
Sharing the same basic principles with CLC, biomass gasification
using chemical looping (BGCL) is an innovative biomass
gasification technique. In the fuel reactor, biomass is converted
into syngas using lattice oxygen from oxygen carrier, while the
reduced oxygen carrier is transported into air reactor for regeneration.
A high quality syngas can be produced in the dual reactor
system. The schematic illustration of BGCL process is shown in