Polymer Electrolyte Fuel Cell (PEFC) System

Types of Fuel Cells

Fuel cells are divided into various types according to the electrolyte (which separates the anode from the cathode) and the operating temperature.

Of the residential fuel cell cogeneration systems available from Osaka Gas, Ene-Farm employs polymer electrolyte fuel cells (PEFCs) and Ene-Farm Type S employs solid oxide fuel cells (SOFCs).

Configuration of and Devices Used in Fuel Cell Cogeneration Systems

Components and Functions

① Fuel reformer
The fuel reformer extracts hydrogen from natural gas.

■ What is a fuel reformer?
The main component of our city gas is methane (CH₄). A fuel reformer produces hydrogen (H₂) for fuel cells through chemical reaction of methane in a reformer.

* When supplying city gas, an odorant containing sulfur compounds is added to the source gas, which is natural gas, for safety reasons.

② Cell stack
A cell stack generates direct current electricity, using hydrogen and oxygen in the air.

■ Power generated by a single cell
A single PEFC generates several hundred millivolts.

■ Power generated by a cell stack
Because the voltage generated by a single fuel cell is too low for household use, in a fuel cell product, dozens of single cells are stacked to generate a high voltage. (The configuration is called a cell stack.)

③ Inverter
An inverter converts generated direct current electricity to an alternating current for use in the home.

④ Heat exchangers
Heat exchangers recover heat from the cell stack and fuel reformer to produce hot water.

⑤ Hot water storage tank
A hot water storage tank stores recovered hot water and supplies it to meet water heating and room heating needs.

⑥ Backup heat source unit
In the event of a shortage of hot water in the hot water storage tank, gas is used to heat water.