623Phosphoric Acid

Phosphoric acid fuel cells (PAFCs) are the most mature fuel cell technology. PAFCs use a concentrated 100% phosphoric acid (H3PO4) electrolyte retained on a silicon carbide matrix and operate at temperatures between 150 and 220°C. Concentrated H3PO4 is a relatively stable acid that allows operation at these temperatures. At lower temperatures, problems with CO poisoning of the anode electrocatalyst (usually platinum) and poor ionic conduction in the electrolyte become problems (Hirschenhofer et al., 1998). The electrodes typically consist of TeflonTM-bonded platinum and carbon (PTFE-bonded Pt/C).

PAFC fuel cells produced by the ONSI Corporation are the world's first commercially available fuel cell product (King and Ishikawa, 1996). Turnkey 200 kW plants are now available and have been installed at more than 180 sites in the United States, Europe, and Japan. Operating at 200°C, the PAFC plant also produces heat for domestic hot water and space heating with an electrical efficiency of 36 to 40%.

Solar Stirling Engine Basics Explained

Solar Stirling Engine Basics Explained

The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

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