A system for converting a fuel, the system comprising: a first moving bed reactor comprising metal oxide particles having a primary component and a secondary component, wherein the first moving bed reactor is configured to provide fuel, CO 2 and steam in a co-current flow pattern relative to the metal oxide particles, wherein the first moving bed reactor is configured to reduce at least a portion of the metal oxide particles with the fuel to produce a first reduced metal oxide, and is further configured to produce a first syngas stream comprising H 2, CO, CO 2 and steam; a second moving bed reactor, configured to operate in parallel with the first moving bed reactor and comprising metal oxide particles having a primary component and a secondary component, wherein the second moving bed reactor is configured to provide fuel, CO 2 and steam in a co-current flow pattern relative to the metal oxide particles, wherein the second moving bed reactor is configured to reduce at least a portion of the metal oxide particles with the fuel to produce a second reduced metal oxide, and is further configured to produce a second syngas stream comprising H 2, CO, CO 2 and steam; a separation unit, in communication with the first moving bed reactor and the second moving bed reactor, and configured to remove the CO 2 from the first syngas stream and the second syngas stream and recycle substantially all of the CO 2 to the first moving bed reactor and the second moving bed reactor; and a third reactor, the third reactor being a co-current fluidized bed reactor in communication with the first moving bed reactor and the second moving bed reactor and configured to oxidize the first reduced metal oxide and the second reduced metal oxide with an oxidizing agent to produce oxidized metal oxide particles and recycle the oxidized composite metal oxide to the first reactor and the second reactor for subsequent reduction reactions, wherein the first and second moving bed reactors have an effective Fe 2 O 3 /CH 4 ratio of 0.5 to 1. a first moving bed reactor comprising metal oxide particles having a primary component and a secondary component, wherein the first moving bed reactor is configured to provide fuel, CO 2 and steam in a co-current flow pattern relative to the metal oxide particles, wherein the first moving bed reactor is configured to reduce at least a portion of the metal oxide particles with the fuel to produce a first reduced metal oxide, and is further configured to produce a first syngas stream comprising H 2, CO, CO 2 and steam; a second moving bed reactor, configured to operate in parallel with the first moving bed reactor and comprising metal oxide particles having a primary component and a secondary component, wherein the second moving bed reactor is configured to provide fuel, CO 2 and steam in a co-current flow pattern relative to the metal oxide particles, wherein the second moving bed reactor is configured to reduce at least a portion of the metal oxide particles with the fuel to produce a second reduced metal oxide, and is further configured to produce a second syngas stream comprising H 2, CO, CO 2 and steam; a separation unit, in communication with the first moving bed reactor and the second moving bed reactor, and configured to remove the CO 2 from the first syngas stream and the second syngas stream and recycle substantially all of the CO 2 to the first moving bed reactor and the second moving bed reactor; and a third reactor, the third reactor being a co-current fluidized bed reactor in communication with the first moving bed reactor and the second moving bed reactor and configured to oxidize the first reduced metal oxide and the second reduced metal oxide with an oxidizing agent to produce oxidized metal oxide particles and recycle the oxidized composite metal oxide to the first reactor and the second reactor for subsequent reduction reactions, wherein the first and second moving bed reactors have an effective Fe 2 O 3 /CH 4 ratio of 0.5 to 1.