FUEL CELLS Xin ge Kang Zhong Le LiU Sergii Dolgykh Aleksei Goland Tallinn University of Technology 2016

OVERVIEW CHP WHAT IS A FUEL CELL? PROCESSES APPLICATIONS, DEVELOPMENT, COSTS CURRENT SITUATION TECHNOLOGY (BASICS, TYPES) ADVANTAGES, DISADVANTAGES CONCLUSION

CHP (Combined heat and power) MasnedøMasnedø CHP power station in Denmark. This station burns straw as fuel.Denmark A cogeneration plant in Metz, France. The 45MW boiler uses waste wood biomass as energy source, and provides electricity and heat for 30,000 dwellings.MetzFrancebiomassdwellings

Whats is a fuel cell? A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction of positively charged hydrogen ions with oxygen or another oxidizing agent. Every fuel cell has two electrodes, one positive and one negative, called, respectively, the anode and cathode. The reactions that produce electricity take place at the electrodes.

Ordinary Combustion process of fuel Fuel Oxygen Combustion products Heat

The process of fuel cell Fuel Oxygen Oxidation Products electricity

The conventional process to produce electrical energy Chemical Energy Heat Mechanical Energy Electrical Energy

Usage of fuel cell

Current Fuel Cell Transportation System Costs per kW, Assuming High Volume Production

History and Development of Fuel Cell in China History of Fuel Cell Development in China Fuel cells are not a new technology to China, but in fact have been researched and developed since the 1970s, when a prototype alkaline fuel cell was developed for use in its domestic space programme. Around 1999, the government extended the electric vehicle R&D investment to include fuel cell technology, and since 2000, a number of demonstration programmes have taken place raising the profile of fuel cells in the eyes of both the government and the public. Current academic and commercial interest in fuel cells ranges from very small portable units for powering torches and consumer electronics, through larger stationary systems for backup power and all the way up to fuel cell electric vehicles and fuel cell buses.

Current situation Current Opportunities for Fuel Cells in China : 1.Transport a. Buses and trucks b. Trains and trams c. Ferries and smaller boats 2.Portable a. Small personal electronics b. education kits and toys (these we classify as micro fuel cells) 3.Stationary( Stationary fuel cells are the largest, most powerful fuel cells. They are designed to provide a clean, reliable source of on-site power to hospitals, banks, airports, military bases, schools, and homes ) a. Combined heat and power (CHP) b. uninterruptible power systems (UPS) c. primary power units

great potential of Fuel cell technology Fuel cells are a promising technology for use as a source of heat and electricity for buildings, and as an electrical power source for electric motors propelling vehicles. Fuel cells have a higher efficiency than diesel or gas engines and it is very clean. Most fuel cells operate silently, compared to internal combustion engines. They are therefore ideally suited for use within buildings such as hospitals. Fuel cells can eliminate pollution caused by burning fossil fuels. Fuel cells do not need conventional fuels such as oil or gas and can therefore reduce economic dependence on oil producing countries, creating greater energy security for the user nation. So, fuel cell technology has great potential in the future.

Electrolysis By providing energy from a battery, water (H 2 O) can be dissociated into the diatomic molecules of hydrogen (H 2 ) and oxygen (O 2 ).

Fuel cell basics fuel cell H2OH2O O2O2 H2H2 heat work The familiar process of electrolysis requires work to proceed, if the process is put in reverse, it should be able to do work for us spontaneously. The most basic “black box” representation of a fuel cell in action:

Technology

Fuel cell basics Thermodynamics H 2 (g) + ½O 2 (g)H 2 O(l) Other gases in the fuel and air inputs (such as N 2 and CO 2 ) may be present, but as they are not involved in the electrochemical reaction, they do not need to be considered in the energy calculations J / mol·K J / mol·K J / mol·K Entropy (S) kJ / mol 00Enthalpy (H) H 2 O (l)O2O2 H2H2 Table 1 Thermodynamic properties at 1Atm and 298K Enthalpy is defined as the energy of a system plus the work needed to make room for it in an environment with constant pressure. Entropy can be considered as the measure of disorganization of a system, or as a measure of the amount of energy that is unavailable to do work.

Fuel cell basics “Putting it together” Figure 3

Types of fuel cells Fuel processing

Types of fuel cells The five most common types: Alkali Molten Carbonate Phosphoric Acid Proton Exchange Membrane Solid Oxide

Alkali Fuel Cell compressed hydrogen and oxygen fuel potassium hydroxide (KOH) electrolyte ~70% efficiency 150˚C - 200˚C operating temp. 300W to 5kW output requires pure hydrogen fuel and platinum catylist → ($$) liquid filled container → corrosive leaks

Molten Carbonate Fuel Cell (MCFC) carbonate salt electrolyte 60 – 80% efficiency ~650˚C operating temp. cheap nickel electrode catylist up to 2 MW constructed, up to 100 MW designs exist The operating temperature is too hot for many applications. carbonate ions are consumed in the reaction → inject CO 2 to compensate

Phosphoric Acid Fuel Cell (PAFC) phosphoric acid electrolyte 40 – 80% efficiency 150˚C - 200˚C operating temp 11 MW units have been tested sulphur free gasoline can be used as a fuel The electrolyte is very corrosive Platinum catalyst is very expensive

Proton Exchange Membrane (PEM) thin permeable polymer sheet electrolyte 40 – 50% efficiency 50 – 250 kW 80˚C operating temperature electrolyte will not leak or crack temperature good for home or vehicle use platinum catalyst on both sides of membrane → $$

Solid Oxide Fuel Cell (SOFC) hard ceramic oxide electrolyte ~60% efficient ~1000˚C operating temperature cells output up to 100 kW high temp / catalyst can extract the hydrogen from the fuel at the electrode high temp allows for power generation using the heat, but limits use SOFC units are very large solid electrolyte won’t leak, but can crack

Advantages of Fuel Cells 1. High efficiency of energy conversion (approaching more than70%) from chemical energy to electrical energy. 2. Low noise pollution & low thermal pollution. 3. Fuel cell power can reduce expensive transmission lines & minimize transmission loses for a disturbed system. 4. Fuel cells are less polluting. The chemical process involved in it is clean. It does not produce polluting exhaust. Mostly the byproducts are water & waste heat, which are environmentally acceptable when hydrogen & air are used as reactants.

Advantages of Fuel Cells 5. Hydrogen-Oxygen fuel cells produce drinking water of potable quality. 6. Designing is modular, therefore the parts are exchangeable. 7. Low maintenance cost. 8. Fuel cell performance is independent of power plant size. The efficiency does not depend on the size of power plant. It remains same for the plants of MW or kW or W size. 9. Fuel cells automotive batteries can render electric vehicles, efficient & refillable.

Disdvantages of Fuel Cells 1.High initial cost. 2.Life times of the cells are not accurately known. 3.Large weight and volume of gas fuel storage system. 4.High cost of pure hydrogen. 5.Lack of infrastructure for distributing hydrogen.

Conclusion Fuel cells are efficient, and clean Also expensive, and require specific humidity, temperature, pressure With more technological advancements, could be used in mass production for various applications Research and development should be aimed at reducing cost and increasing life. Not an instant fix for the energy crisis, but definitely a major component

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