Fuel cells have been discovered to be quite effective in delivering energy to power modern vehicles. There are a number of questions raised as well on the true efficacy of these and people are wondering if the performance can really make up for the cost. Here is a brief overview of fuel cells and how they may influence vehicles in the future.
What Is A Fuel Cell?
A fuel cell is a device that converts electrochemical energy. From different external amounts of fuel on the anode part and oxidant from the cathode side, electricity can be generated which responds to electrolytes.
The electrolyte typically stays in the cell while the reactants move in and reaction products move out. As long as the required movements are maintained, fuel cells can operate nonstop. Parallel or series circuits are made through combinations of fuel cells in order to produce higher energy and voltage. The design is called a fuel cell stack.
Unlike batteries which chemically store electrical energy in a closed system, fuel cells consume reactants that need to be replenished. The electrodes in batteries react and change during charging or discharging but fuel cell electrodes are more stable and catalytic. It is possible to have various combinations of fuel and oxidant like hydrogen oxygen, hydrocarbons, air and alcohols.
Fuel cells work by catalysis wherein the component electrons and protons of the reactant fuel are separated. The electrons are forced to move through a circuit which then converts into electrical power. A platinum group metal or alloy composes a catalyst and a process ensues getting the electrons back in to mix with the protons and the oxidant. Waste products are the end result which comes in the form of carbon dioxide, water and other simple compounds.
In a PEMFC or proton exchange membrane fuel cell design, the electrolyte divides the anode and cathode sides. Hydrogen diffuses to the anode catalyst on the anode side which later on dissociates into electrons and protons. The protons are sent through the membrane towards the cathode while the electrons are forced into a circuit which then generates electrical power. Oxygen molecules react with the electrons that were forced into circuit and protons to form water on the cathode catalyst.
How Efficient Are Fuel Cells?
The efficiency of fuel cells depends on the quantity of power drawn. More drawn power will equate to increased current. Increased current also equates to increased losses in fuel cells so efficiency is reduced as more power or current is drawn.
Fuel cell efficiency is almost proportional to its voltage since drawn current or losses lead to voltage drops as well. If a fuel cell has 50% efficiency, this means that half of the hydrogen energy content will be converted into electrical energy while the rest will be converted into heat.
Fuel cells are not limited in the Carnot cycle efficiency like other combustion engines since these do not work with a thermal cycle. Fuel cells still fall under the laws of thermodynamics but are more efficient compared to the thermal efficiency of the Otto cycle. Electrical output needs to turn into mechanical power in order to produce propulsion. Fuel cells may also convert chemical energy into electrical energy quickly with low power densities and with pure oxygen and hydrogen as reactants.
Influence As Alternate Fuel
There are various benefits provided by fuel cells which show that it can be a very feasible source of alternate fuel. First is pollution reduction since fuel cells uses a radically different approach in producing energy thus reducing byproducts formed from conventional combustion processes.
Countries all over the world are looking for domestic sources in order to continuously produce energy. Since fuel cells use hydrogen which can easily be derived from water, it simply shows that fuel cells can be more economically and ecologically wise in the near future.
Pure hydrogen powers fuel cells making it around 80% efficient. Through an electric motor and inverter, electrical energy can be converted into mechanical energy spurring propulsion. The proportional energy-efficiency ratio of fuel cells mean that an electric motor with 80% efficiency is also 80% efficient in producing electrical power and is 80% efficient in converting it into mechanical power.
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