Carbonate MCFC

Molten carbonate fuel cells (MCFCs) are currently being developed for natural gas and coal-based power plants for electrical utility, industrial, and military applications. MCFCs are high-temperature fuel cells that use an electrolyte composed of a molten carbonate salt mixture suspended in a porous, chemically inert ceramic lithium aluminium oxide (LiAI02) matrix. Since they operate at extremely high temperatures of 650°C and above, non-precious metals can be used as catalysts at the anode and cathode, reducing costs. 

Improved efficiency is another reason MCFCs offer significant cost reductions over phosphoric acid fuel cells. MCFCs can reach efficiencies approaching 60 percent, considerably higher than the 37-42 percent efficiencies of a phosphoric acid fuel cell plant. When the waste heat is captured and used, overall fuel efficiencies can be as high as 85 percent. 

Unlike alkaline, phosphoric acid, and polymer electrolyte membrane fuel cells, MCFCs don t reguire an external reformerto convert more energy-dense fuels to hydrogen. Due to the high temperatures at which they operate, these fuels are converted to hydrogen within the fuel cell itself by a process called internal reforming, which also reduces cost. 

Although they are more resistant to impurities than other fuel cell types, scientists are looking for ways to make MCFCs resistant enough to impurities from coal, such as sulphur and particulates. 

The primary disadvantage of current MCFC technology is durability. The high temperatures at which these cells operate and the corrosive electrolyte used accelerate component breakdown and corrosion, decreasing cell life. Scientists are currently exploring corrosion-resistant materials for components as well as fuel cell designs that increase cell life without decreasing performance. 

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Molten carbonate (MCFC) CHP, power plants Molten carbonate 875-925... 

Several types of fuel cell are currently under development, using different electrolyte systems phosphoric acid (PAFC), alkaline, molten carbonate (MCFC), regenerative, zinc-air, protonic ceramic, (PCFC), proton exchange membrane (PEM), direct methanol (DMFC), and solid oxide (SOFC). The last four contain solid electrolytes. 

Molten Carbonate (MCFC) These cells use a mixed alkali-carbonate molten salt electrolyte and operate at about 600 °C. They are being developed for continuously operating facilities, and can use coal-based or marine diesel fuels. 

Molten carbonate (MCFC). The cell operates at 650°C and uses hydrogen or carbon monoxide as anode fuel, which reacts with carbonate... 

There are other types of fuel cells of which proton exchange membranes (PEMFC), molten carbonate (MCFC), and solid oxide (SOFC) are the most promising. These fuel cells are at various stages of technology demonstration and are not commercially available. Each type of fuel cell has its own preferred range... 

Molten carbonate (MCFC) CO3- 650 °C Suitable for medium to large scale CHP systems, up to MW capacity. 

Systems studies to date indicate that fuel cell/turbine hybrids could realize a 25 percent increase in efficiency and 25 percent reduction in cost for a comparably sized fuel cell [14,15], The synergy realized by fuel cell/turbine hybrids derives primarily from using the rejected thermal energy and combustion of residual fuel from a fuel cell to drive the gas turbine. This leveraging of the thermal energy makes the high-temperature molten carbonate (MCFC) and solid oxide fuel cells (SOFC) ideal candidates for hybrid systems. Use of a recuperator contributes to thermal efficiency by transferring heat from the gas turbine exhaust to the fuel and air. 

Molten Carbonate (MCFC) Liquid solution of lithium, sodium, and/or potassium carbonates soaked in a matrix 600-1000 Electric utility Higher efficiency, fuel flexibiUty, inexpensive catalysts... 

Li et al. (2010) tested four different Australian raw coals as fuels in direct carbon MCFCs. They found that the cell performances are highly dependent on a coal s intrinsic properties, in particular its chemical composition and concentration of oxygen-containing surface groups. Impurities such as AI2O3 and Si02 lead to an inhibitive effect, whereas CaO, MgO, and Fc203 exhibit a catalytic effect on the electrochemical carbon oxidation reaction. 

There are some other fuel cells, such as phosphoric acid (PAFC) or molten carbonate (MCFC) [4], that are commercially available but will probably not find significant implementation due to high cost and durability issues. 

Polymer electrolyte PEFC Phosphoric acid PAFC Molten carbonate MCFC Solid oxide SOFC... 

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