Reformed methanol fuel cell
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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),[1] a fuel cell, a fuel cartridge, and the BOP (the balance of plant).[2]
Storage
The fuel cartridge stores the methanol fuel, which is often diluted with up to 40% (by volume) water.
Fuel processing system (FPS) in
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.
Fuel cell
→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.
Fuel processing system (FPS) out
→Tail gas combustor (TGC) catalytic combustion afterburner or (catalytic combustion) with a platinum-alumina (Pt–Al2O3)[3] catalyst[4][5]→condenser
Balance of plant
The balance of plant (BOP) consists of any fuel pumps, air compressors, and fans required to circulate the gas and liquid in the system. A control system is also often needed to operate and monitor the RMFC.
State of development
RMFC systems have reached an advanced stage of development. For instance, a small system developed by Ultracell for the United States military, , has met environmental tolerance, safety, and performance goals set by the United States Army Communications-Electronics Research, Development and Engineering Center, and is commercially available.
Larger systems 350W to 8 MW are also available for multiple applications, such as power plant generation, backup power generation and battery range extension. One application in the field is improving performance of a heavy duty smaller electric vehicle Video of solution
See also
- Methane reformer
- Methanol (data page)
- Methanol economy
- Micropump
- Fuel cell
- Glossary of fuel cell terms
- Hydrogen technologies
- Portable fuel cell applications
References
- ↑ fuel processing system
- ↑ Balance of plant
- ↑ Pt-Al2O3
- ↑ Catalytic Processes for Clean Hydrogen Production from Hydrocarbons
- ↑ Brian J. Bowers; Jian L. Zhaoa; Michael Ruffoa; Rafey Khana; Druva Dattatrayaa; Nathan Dushmana; Jean-Christophe Beziatb (2007). "Onboard fuel processor for PEM fuel cell vehicles". International Journal of Hydrogen Energy. 32 (10–11): 1437–1442. doi:10.1016/j.ijhydene.2006.10.045.