Table of Contents
Hydrogen Fuel cell:
The greenhouse gases is making our atmosphere hotter more unpredictable and turbulent. The emission free mobility has long been more than just a dream. There are many reasons but the vehicles are major cause of global warming and for that the technology moves into emission gas or electricity. Hydrogen is the most abundant element in the universe and naturally binds to other element such as oxygen. Hydrogen has high energy content which is used as an alternative fuel. When it is consumed in a fuel it produces electricity. Hydrogen base fuel cells are used in a wide range of application like transportation, material handling and backup power application. The diesel and petrol are limited and the way that these fuel are using there is chance that it will be finish one day. Also the petrol and diesel based vehicles produce pollution. The conventional combustion based technologies are used in vehicles and power plants. It is an opportunity to fuel cell to provide its benefits. Hydrogen is used to power up fuel cells of electrical vehicles. It exists more efficiency over conventional engine vehicles. It does not produce any emissions and produce only warm air and water vapours. Now a days batteries are used which has very short duration which work up to some hours or a day of run time. When we are looking at extended mission we need a different power source, we need a different energy conversion source so the fuel cells offer days, weeks, up to two months of runtime.
In fuel cell the chemical energy is converted into electrical energy in a reaction that eliminates the combustion of the fuel. So in case most of the conventional energy the combustion of the fuel takes place. In fuel cell we do not have combustion of fuel the chemical energy is directly converted into mechanical energy. Unlike heat engine that operates on a thermodynamic power cycle, the performance of the fuel cell is not restricted by the second law of thermodynamics. The sign convention for the anode and the cathode is same for the batteries and fuel cell, and for thermionic, thermoelectric, and MHD generators. Negative ions or electrons moves from the cathode to the anode within the device, so that the conventional current now is from the cathode to the anode in the external circuit. The elemental particles referred to as charge carriers. A fuel cell is similar to battery it takes hydrogen as a fuel and when hydrogen goes inside the anode will ionize the hydrogen and the negative charge of the hydrogen will pass from the anode to cathode through conduction process. While the hydrogen ion is combined with oxygen to form water and the remaining energy is released in the form of heat.
Chemical energy —> Heat—>Mechanical motion—>Electricity
In which burn the conventional fuel which will produce heat and this heat will be converted into mechanical energy. The mechanical energy is then converted into electrical energy.
In fuel cell through small chemical reaction the electrical energy is produce. Fuel cell does not produce any environment pollution.
Application of the fuel cells:
The fuel cells can be used in cars, power stations; space craft’s where we can use it as source of energy. Nasa uses hydrogen fuel to launch the space shuttle. Fuel cells have many additional advantages compare to the batteries because the batteries needs to be charged after certain interval. For example if we put a battery in electrical car then after certain time the battery will be discharge and its charging will require a lot of time. So in majority cases we consider that the future of the vehicles is fuel cells not the battery. In fuel cells we have hydrogen as a fuel and once we fill the hydrogen in the fuel tank then we have enough energy to move to thousands of kilometer. The major companies like General motors, Siemens, Toyota, Honda are doing research on the fuel cells. The fuel cell vehicle produce the required electricity on board through a chemical reaction of the hydrogen and oxygen. There basic focus is to use fuel cell in the automobiles. There are certain company which are developing fuel cell based cars like Nicola. They produce emissions without any emissions.
Fuel cell configuration:
A fuel cell consist of two electrodes namely as anode and cathode and sandwiched around an electrolyte. An electrolyte is a substance solid or liquid capable of conducting owing ions hydrogen from one electrode to other.
Every cell also has an electrolyte which carries electrical charged particles from one electrode to other and a catalyst which speed the reaction at the electrode. A single fuel cell generates a tiny amount of direct current (DC) electricity. A converter is used to produce AC current. In practice many fuel cells are usually assembled into a stack in series or parallel to produce huge amount of current.
A single fuel cell consists of multiple components. The bipolar plates channel oxygen and hydrogen to the anode and cathode catalyst layer of PEM. Oxygen is drawn from ambient air and fed to the cathode side of the bipolar plate.
Fuel Cell Principle of construction and working:
The fuel cells works like a battery but they do not run down or need recharging. They can produce electricity constantly. Fuel cells have higher efficiency then combustion engine. It converts the chemical energy in to electrical energy. The hydrogen is fed in to one side of the each of these bipolar plates. Hydrogen is passed through the anode and oxygen is passed through cathode. Each of these bipolar plates there is a membrane electrode assembly with a catalyst layer that convert the hydrogen and oxygen in to water. At anode the hydrogen is split into electrons and protons by the catalyst. The positive particles passed through the membrane while the negative particles cannot pass through it. However atom need equalize charge in order to achieve this electron must change the path. The hydrogen as fuel is oxidized on the anode and oxidant reduced on the cathode. One species of ions are transported from one electrode to the other through the electrolyte to combine their counterparts while electron travels through the external circuit producing the electrical current. The end product of this is water which will form at cathode when the hydrogen and oxygen will combine. Due to the electrode moving parts the cells are highly reliable in its operation. The hydrogen fuel cells are useful in automobiles industry also.
Hydrogen fuel cell engines:
Hydrogen fuel cell engines can power vehicles or backup generator for large computer operation. They produce electrical power without any emission. The hydrogen fuel cell is the heart of the engine. The engine blower pushes in air the fuel tank then feeds in the hydrogen gas. Hydrogen and oxygen react to create electricity. Each fuel cell is made up of five parts on each there is channelled plate made primarily of carbon which will conduct electricity. Hydrogen enters the cell through the first plate which channels it through the next component. A chemical treated paper which conducts gas and electricity then the hydrogen enters through the membrane where it splits into protons and oxygen. The proton reacts with the oxygen producing water. The water passes through another paper to the cell outer plate where a pump draw it away meanwhile the electrons travel to the end of the stack of the fuel cells to electrical wires. After assembling the stack the fuel cells are compress in a hydraulic press. Compression helps the current flow smoothly through cell to cell. The stack is press in the rubber gasket around each plate so the hydrogen cannot leak air. A quality test with nitrogen gas to verify the seal before releasing the press, they install high strength steel rods to bind the compress cell together for the stack size. The rods apply three tons of pressure with the stack now off the press which are hook up an electrical circuit which monitor the voltage of each fuel cell after securing the connector to the stack with an adhesive strip. It is just a matter of connecting one to each fuel cell. It contains a special type of epoxy to secure the connection and contains silver to conduct electricity. They then mount the circuit board and the plastic cover to protect it. The fuel stack is now fully assembled and moves on for testing.
The technician mounts it on a test station and connects a hydrogen line an airline and a water line for cooling. The automated performance test is performed by the testing machine for three hours. Then the technician mounts the stack on to the engines structural frame and then installs the hydrogen recirculation pump. A water pump is then pumped is then fitted which calls the fuel cell by pumping in cool water. They then install the components which supply the hydrogen stored at high pressure in the fuel tank and it is that pressure that pushes the gas through stainless steel fuel lines. Then the fuels that blows outside air into the fuel cell to react with hydrogen. This filter removes dust and other contaminants drawn in from that fan into the fuel. In the meantime it is assembled the computer that control the whole engine. They connect the wires from the fan, pumps and other engines components to the computer. They connect the fuel cell output wiring which are the wires that carry the fuel cell creates and sends it to whatever vehicle or device. The engine is powering a tiny portion of the cells output powers the pumps and other engines components. Now the engine is fully assembled undergoes extensive performance and safety testing. Once it passes every test then a final visual inspection is perform and then sheet metal cover is installed on it. The hydrogen cell is now ready to be delivered to customer.
Hydrogen fuel train:
Hydrogen fuel is revolution for the future of the mobility. The world first hydrogen fuel cell train was started by Alstom four years ago. Hydrogen train technology is exciting innovation that has the potential to transform the railway making journey cleaner and greener by cutting the carbon dioxide emissions even further.
The heart of the power generation is the fuel stack. The stack is made up of individual cells.
Hydrogen fuel train working:
High derail vehicles use the chemical energy of hydrogen by reacting hydrogen with oxygen in a fuel cell to run electric motors. The fuel cells and hydrogen tanks are mounted on the roof of the train. The hydrogen fuel cell power module is the heart of the system. The hydrogen supply from the storage tanks and reacts with oxygen in a fuel cell in this reaction generates electricity, heat and water. This electricity from the fuel cell powers the wheels via traction unit during acceleration and is stored in lithium ion battery. It has the same performance as traditional diesel train. The hydrogen will be the future fuel and step by step it will replace all current fossil fuels. Similar to conventional combustion powered vehicles filing the tank will only takes few minutes. Hydrogen is stored in the vehicle carbon fibre tanks. When the driver presses the accelerator hydrogen will start flowing at the cathode side. The fuels cells are connected in series. The voltage of the fuel stack is a function of the number of cells. The current generated by the fuel cell is conducted to the electric motor which powers the vehicle.
Photovoltaic are ever advancing technologies used throughout the world which create the electricity from the sun however storing the electricity for later use is the biggest challenge that users facing of this technology. When the energy is not feed to the grid people had to rely solely on batteries for energy storage which are expensive and difficult to dispose off in a safe manner and have to be replaced frequently. But now there are other viable technologies and systems for storing energy. The system that we will used hydrogen energy storage which has several important advantages.
- It is 100% clean
- Long life in storage
- No limit on product or store
The technology that makes this possible is hydrogen electrolysis. The electrolytic process will be used to split water in to hydrogen and oxygen.
The machine that performs this operation is hydrogen electrolyser to convert the electrical energy and store in the tanks in the form of hydrogen which can be later transform back in to electricity. Hydrogen electrolysis from water is usually undertaken with liquid alkaline or polymer electrolytic membrane electrolysers. The alkaline electrolyser works by immersing two electrodes in a liquid electrolyte. When a voltage is applied the product gases are released in this case thee oxygen and hydrogen. To store enough hydrogen for regular use we will need a giant tank or an additional compressor.