Indirect methanol fuel cell
Reformed Methanol Fuel Cell (RMFC) or Indirect Methanol Fuel Cell (IMFC) systems are a subcategory of proton-exchange fuel cells where, the fuel, methanol (CH3OH), is reformed, before being fed into the fuel cell. RMFC systems offer advantages over direct methanol fuel cell (DMFC) systems including higher efficiency, smaller cell stacks, no water management, better operation at low temperatures, and storage at sub-zero temperatures because methanol is a liquid from -97.0 °C to 64.7 °C (-142.6 °F to 148.5 °F). The tradeoff is that RMFC systems operate at hotter temperatures and therefore need more advanced heat management and insulation. The waste products with these types of fuel cells are carbon dioxide and water.
Methanol is used as a fuel because it is naturally hydrogen dense (a hydrogen carrier) and can be steam reformed into hydrogen at low temperatures compared to other hydrocarbon fuels. Additionally, methanol is naturally occurring, biodegradable, and energy dense.
RMFC systems consist of a fuel processing system (FPS), a fuel cell, a fuel cartridge, and the BOP (the balance of plant).
The fuel cartridge stores the methanol fuel, which is often diluted with up to 40% (by volume) water.
Methanol→Partial oxidation(POX)/Autothermal reforming (ATR)→Water gas shift reaction (WGS)→preferential oxidation (PROX) The reformer converts methanol to H2 and CO2, a reaction that occurs at temperatures of 250 °C to 300 °C.
→The membrane electrode assembly (MEA) fuel cell stack produces electricity in a reaction that combines H2 (reformed from methanol in the fuel processor) and O2 and produces water (H2O) as a byproduct.
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