To our knowledge, the lowest voltage used to achieve economical rates and high acid concentrations for an SO 2 -depolarized cell is 0.66 V at 500 mA/cm 2 and 7 M acid concentration. These values are nearly at the benchmark of 0.6 V and 500 mA/cm 2 proposed for the economical implementation of the two-step Westinghouse cycle. However, it should be noted that the cycle proposed herein may have different considerations for what constitutes economic viability as the chemical conversion of low-cost feedstocks into char and H 2 may provide useful energy to the cycle. For comparison, the most efficient alkaline water electrolyzer to date has been demonstrated 1.586 V at 500 mA/cm 2 . Feedstock costs for biomass and MSW vary significantly based on location, but have been estimated to cost between +20 and -55 $/ton as a waste product. In this economic analysis, we will use 20 $/ton as our feedstock price instead of a negative value because further separation and purification of MSW to isolate organic material would be necessary before it may be used in this cycle. Figure plots the estimated cost of H 2 production using alkaline water electrolysis and this proposed process both with and without utilization of the biochar (e.g. equations 1a verses 1b). This analysis assumes that external potentials of 0.66 V (SO2-depolarized) and 1.586 V (conventional alkaline water electrolysis) are applied, 80% utilization of produced thermal energy, and MSW (represented by cellulose) feedstock prices of 20 $/ton (see SI for more details on calculations). These data suggest that the use of MSW to regenerate an SO 2 -depolarized cell for production of H 2 may be economically advantageous over a wide range of electricity prices. These data also suggest that utilizing the carbon or sequestering it as biochar may only have a small impact of the final production cost of H 2 .