Fuel Cell Battery
Fuel Cell Battery : Introduction
A fuel cell battery directly converts chemical energy produced by the oxidation of fuel into electric energy.
Fuel cell battery is a generating unit and basically like that of a normal chemical battery in the sense that it uses the reaction of oxidation-reduction. However, unlike a chemical battery that reacts in a closed system, reactants are continuously supplied from the outside and products from the reaction are continuously removed to the outside of the system.
The most typical product is an oxy-hydrogen fuel cell, which was discovered in 1839 by Englishman W.R. Grove (1811-96). After 5kW of oxy-hydrogen fuel cells were experimented on in 1959 by Englishman F.T. Bacon, oxy-hydrogen fuel cells were beginning to come into the spotlight. Shortly thereafter, from the 1960s-1970s, fuel cells were used by NASA in the Gemini and Apollo spaceship. Today, they are being commonly used.
From 2003 Samsung SDI started an earnest development of fuel cells for mobiles. One of the major ongoing studies has been fuel cells that generate electricity by resolving hydrogen from LPG gas and methanol. SDI has also studied core components related to reliability. Now the company is developing 200W class PEMFC portable system (portable fuel cell that can be used for power supply for recreational vehicles like yachts and camping cars) and 25w class DMFC system (fuel cells using methanol as fuel) as a portable electric power source, commonly used by the military.
Based on the core technologies accumulated, Samsung SDI plans to focus on developing SOFC, solid oxide fuel cells. As the next generation fuel cells for decentralized electric power generation, Samsung SDI plans to establish SOFC as the basis of their future energy business. With attractive attributes of minimal discharging pollutants, the technology is environment-friendly and has the potential to reduce resource-exhaustion problems due to use of various fuels as well as petroleum.
The price of fuel, which is consumed when charging a fuel cell, is cheaper than the cost of charging other secondary cells like lithium ion cells. However, the price of a fuel cell itself is substantially expensive. Fuel cells are divided into PEMFC, DMFC, PAFC, AFC, MCFC and SOFC according to the kinds of electrolytes used in the cells. Especially SOFC, which is the third generation fuel cell, is mainly studied in developed countries for home and car use. SDI is still not seen as technically advanced in this area in comparison to other fuel cells that they specialize in. At SDI, it is still in the first stage of the development. However, as of recently, SOFC is on the rise and coming into the spotlight in the field of decentralized power generation system development due to fuel cells’ attributes of having high energy density compared to existing primary and secondary cells, as well as pollution-free energy sources that hardly produce pollutants.
Fuel Cell Battery : Characteristics
High Energy Conversion Efficiency
A fuel cell battery has high energy conversion efficiency since it transforms chemical energy into electric energy directly
Fuel Flexibility
There are many various substances for fuel with a wide array of different options.
Co-Generation Capability
Electric chemical reaction is exothermic, which occurs within the fuel cell system. At this time, the heat produced can be utilized in various purposes.
Rapid Load Response
Adaptive capability to external load is higher than that of an existing chemical battery.
DMFC System for Military
DMFC is the direct methanol fuel cell system that generates electricity by using liquid methanol as fuel. It is commonly used as an portable electric power source for the military.
Both disposable primary cells, which are used for battlefields and military operations, and charge-type secondary cells? have continuous problems. that is, enormous quantity is necessary for electric power supply and the cost is high. Now high-efficient DMFC system is coming into the spotlight, which has 3 times more efficient energy density per weight(Wh/kg) than existing batteries and is possible to serial generation by replacing fuel cartridge without charge time.
Fuel Cell System For Decentralized Generation
Because of economic growth, the demand of developing countries’ use of electric power will sharply increase, and OECD countries will need to replace old equipments of existing electric power networks. The decentralization of generating equipment however, is more efficient since large-scale investment in power transmission and distribution is essential when constructing central generating units.
Since electric power systems are becoming Smart Grid from now on, the importance of decentralized power generation is coming into the spotlight in order to guarantee the most efficient electric power source in using optional electric power.
※ Smart Grid : It is an intelligent electric power system that improves electric power efficiency by making it possible for users to use electric power optionally through the exchange of information between users and suppliers.
Decentralizing Generation System
Decentralized generation systems are unlike central generation methods like thermal and nuclear plants. Decentralized generation systems are generating systems that are located near places of demand in small scales(dozens KW ~ tens of thousands KW). They can cause energy reduction by reducing power transmitting and distributing equipments, and are constantly generating high-efficiency.
Kinds of Decentralizing Generation System
The decentralized generation system using fossil fuels, which now occupies more than 95% of the decentralized generation market, is great in price, but has setbacks in noise and greenhouse gas. Meanwhile, fuel cell system is highly efficient and an environmentally-friendly system that improves generating efficiency by 40~60%, reduces carbon dioxide discharge by 30~50%, (compared to the decentralized generation system using fossil fuels), and produces almost zero Nox gas.
| Section | Gas Turbine | Diesel Engine | Fuel Cell | |
|---|---|---|---|---|
| Efficiency | Generation | 22~36% | 27~45% | 40~60% |
| Generation + Heat | 70~75% | 70~80% | 65~80% | |
| System Capacity (MW) | 1~500 | 0.03~5 | 0.01~2 | |
| Environment | Noise | Middle | High | Low |
| NOx (g/kWh) | 0.3~0.5 | 10 | 0.005~0.01 | |
| CO2 (g/kWh) | 580~680 | 650 | 305~490 | |
| Installation Cost | 650~900 | 350~500 | 2,000~3,500 | |
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※ The Average Generating Efficiency of Thermal Generation : 20~30%
The Kinds of Fuel Cells for Decentralizing Generation
Currently, the supplied fuel cells for decentralized generation are the phosphoric acid fuel cells(PAFC) and the molten carbonate fuel cells(MCFC). 180MW(900 units) of them were supplied until 2008.
PAFC is not economically efficient because it uses platinum catalyst. MCFC system is also limited by its short life because of metal elution.
The solid oxide fuel cell(SOFC) theoretically has the highest energy efficiency, and it is coming into the spotlight as the fuel cell for the next generation’s decentralized electric power generation.
| Date of Development (Year) | The Kinds of Fuel Cells | Fuel Cells |
|---|---|---|
| 1990 | PAFC (First Generation ) |
Low efficiency (under 40%) compared to other fuel cells. Low economical efficiency because of using platinum catalyst |
| 2000 | MCFC (Second Generation) |
Most proper for commercial applications. High generation efficiency(47%). Planning for the mass production by 2012. |
| 2015 | SOFC (Third Generation) |
Highest generation efficiency(55%, 70% when connected with turbines). Using various fuels. |
The Formation of SOFC System
The whole system consists of ceramic cells(the fundamental unit of generation) stacks(combination of cells), mechanical BOP(M-BOP) that helps a stack drive, and electronic BOP(E-BOP)
