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Hydrogen Story

HYDROGEN STORY

Fuel cell

● Fuel cell is?
 A fuel cell is an energy conversion device that allows hydrogen to run almost everything in a versatile way. The existing power generation method caused energy loss due to heat and kinetic energy in the process of generating electricity. The power generation efficiency of the fuel cell is more than 30 to 60 percent, even considering all of these losses. In addition, when using cogeneration, the overall system efficiency reaches 80%. Unlike conventional internal combustion engines, fuel cells do not generate electricity through combustion. Electricity is obtained through electrochemical reactions of hydrogen and oxygen, while producing only water and heat at the same time. It behaves like a battery, but the biggest difference is that the battery is a device that stores electricity but the fuel cell is a generator that produces electricity.
 The battery converts the chemicals stored inside to electricity, and when the chemicals are exhausted, While it has reached the end of its life or requires a long charging time, fuel cells receive electricity from the outside like existing internal combustion engines to supply electricity.
 It has a fast charging time to produce and can generate infinite power as long as fuel allows. All fuel cells have fuel poles and air poles separated by electrolytes, in which hydrogen is divided into hydrogen ions and electrons. The polymer membrane of the electrolyte passes only hydrogen ions, and electrons remain in the cathode inside the membrane. Hydrogen ions combine with oxygen in the air electrode to become water, and electric current is generated by the potential difference between the positive electrodes.
● Advantages of Fuel Cells
It is a distributed system that can be easily used wherever power is required. It is economical because there is no electricity wasted due to reduction
of construction cost and transmission loss.
The eco-friendly
Hydrogen fuel cell produces only heat, water, and electricity, and does not emit air pollutants and greenhouse gases because it plays a big role in improving the environment and allows us to breathe cleaner air.
Energy-efficient
Fuel cells are two to three times more efficient than existing internal combustion engines. Fuel cells generate both heat and electricity, but they differ by type, but in the case of power production efficiency, they are 30 to 60%. Considering the thermal efficiency, the efficiency is about 80%.
Fuel flexibility
There are many types of fuel cells that use different fuels such as fuel flexibility hydrogen, natural gas, methanol, ethanol, and biogas, they can be used as a clean energy source.
Versatile
Fuel cell has adjustable capacity and can be used from milliwatts to megawatts. It can be applied to various applications from mobile phones to automobiles.
Complementary
Fuel cells can be easily combined with other energy technologies. For example, it can have an effect synergistically combining with batteries, wind turbines, solar panels, high capacity capacitors.
● Types of fuel cells
Types/Characteristics High temperature fuel cell Low temperature fuel cell
Division Molten carbonate
fuel cell
(MCFC)
Solid oxide fuel cell
(SOFC)
Phosphoric Acid Fuel Cell
(PAFC)
Alkaline Fuel Cell
(AFC)
Proton-exchange membrane fuel cell
(PEMFC)
Direct Methanol Fuel Cell
(DMFC)
Operating
Temperature
550~700℃ 600~1000℃ 150~250℃ 50~120℃ 50~100℃ 50~100℃
Main Catalyst Perovskite Nickel Platinum Nickel Platinum Platinum
State of
Electrolyte
Li/K alkali
carbonates mixture
YSZ GDC H3PO4 KOH Ion exchange
membrane
-14
Electrolyte
Support
immobilized
liquid
Solid immobilized
liquid
Solid Solid
Charge transfer Ions CO32- O2- H+ OH- H+ H+
Possible
Fuel
H2,CO
(Natural, coal gas)
H2,CO
(Natural, coal gas)
H2,CO
(methanol, coal gas)
H2 H2
(methanol, coal gas)
methanol
Necessity of
External fuel reformer
NO NO YES YES YES YES
Efficiency(%LHV) 50~60 50~60 40~45 - <40 -
Main Use Large-scale power generation,
Small business facilities
Large-scale power generation,
Small business facilities,
Mobile power supply
Small business facilities,
Biogas plant
Space projectile power Transportation power,
Household power,
Portable pow
Portable power
Characteristic High power generation efficiency,
Internal reforming possible,
Cogeneration power response possible
High power generation efficiency,
Internal reforming possible,
Combined power generation possible
High durability of CO,
Cogeneration power response possible
- Low temperature operation,
High power density
Low temperature operation,
High power density
Task assigned Material corrosion,
Molten salt volatilization power response possible
High temperature deterioration,
Heat destruction generation possible
Material corrosion,
Phosphoric acid outflow
Prevention of leakage from electrolyte High temperature operation impossible,
High material/ Processing cost (expensive catalyst and electrolyte),
Low efficiency
High temperature operation impossible,
High material/ Processing cost,
Methanol crossover problem
Source : Renewable Energy White Paper 2016