Fuel cells are electrochemical devices that convert chemical energy in fuels into electrical energy directly, promising power generation with high efficiency and low environmental impact.
A fuel cell produces electricity, water, and heat using fuel and oxygen in the air. Water is the only emission when hydrogen is the fuel.
As hydrogen flows into the fuel cell on the anode side, a platinum catalyst facilitates the separation of the hydrogen gas into electrons and protons (hydrogen ions). The hydrogen ions pass through the membrane (the center of the fuel cell) and, again with the help of a platinum catalyst, combine with oxygen and electrons on the cathode side, producing water. The electrons, which cannot pass through the membrane, flow from the anode to the cathode through an external circuit containing a motor or other electric load, which consumes the power generated by the cell.
The voltage from one single cell is about 0.7 volts – just about enough for a light bulb – much less a car. When the cells are stacked in series, the operating voltage increases to 0.7 volts, multiplied by the number of cells stacked.
Most fuel cell power systems comprise a number of components:
a) Unit cells, in which the electrochemical reactions take place
b) Stacks, in which individual cells are modularly combined by electrically connecting the cells to form units with the desired output capacity.
c) Balance of plant which comprises components that provide feed stream conditioning (including a fuel processor if needed), thermal management, and electric power conditioning among other ancillary and interface functions
Benefits of fuel cell
a) Low emission
A fuel cell operating on pure hydrogen emits zero emissions at the source. Based on measured data, a stationary fuel cell power plant creates less than one ounce of pollution per 1,000 kilowatt-hours of electricity produced. Conventional combustion generating technologies create 25 pounds of pollutants for the same amount of electricity.
Fuel cells also reduce noise emissions. Since fuel cells do not rely on combustion and have few moving parts, they are very quiet – about 60 decibels, the volume of a typical conversation. And since noise pollution is all but eliminated, fuel cells can be sited indoors or outdoors without being obtrusive.
Fuel cell electric vehicles (FCEVs) are the least polluting of all vehicle types that consume fuel directly, emitting zero emissions during use.
b) High Efficiency
Because fuel cells create energy electrochemically, and do not burn fuel, they are fundamentally more efficient than combustion systems. Fuel cell systems today achieve 40-50 percent fuel-to-electricity efficiency using hydrocarbon fuels such as natural gas.
c) Energy Security
Hydrogen can be produced from domestic resources, eliminating the need to import foreign oil.
Because fuel cells do not have to be connected to the electrical grid, they are a form of distributed generation that allows the country to move away from reliance on high voltage central power generation, which is vulnerable to attacks and natural disasters. Fuel cells aid critical communications networks, providing crucial connections and continuous power during weather events such as hurricanes and snow storms that can cripple the grid. Fuel cells have proven themselves during these violent weather events over the past few years, providing reliable backup power to schools, hospitals, and grocery stores, all of which deliver crucial goods and services to communities. Fuel cells are also rugged, and can be sited in harsh terrain, extreme climates, and rural areas without infrastructure.
Whether in rough terrain or extreme climates, fuel cells can be sited wherever power is needed. Uninterrupted power supply (UPS) units currently backup cell towers in remote locations, and portable fuel cells have proved themselves alongside the U.S. military in theater, providing soldiers critical power with low heat and noise signatures in extreme environments.
Fuel cells are modular, and can be scaled up depending on the power needs of a facility. Larger fuel cells can be linked together to achieve multi-megawatt outputs, while smaller ones can satisfy specific power needs at residential, telecommunications, or small commercial facilities.
f) Lightweight and Long Lasting
Fuel cells are being developed for portable electronic devices such as laptops and cell phones. Fuel cells provide a much longer operating life than a battery, and since fuel cells have a higher energy density, they are lighter than an equivalent battery system. Fuel cells do not require recharging; as long as fuel is present, the system will continuously generate electricity.