Hydrogen is a clean-burning fuel, and when combined with oxygen in a fuel cell, it directly converts the chemical energy in hydrogen to electrical energy, with only pure water and heat as useful byproducts. The two main applications for hydrogen fuel cells are:
- stationary power sources
- hydrogen fuel cell vehicles (FCVs).
Sources of Hydrogen
Hydrogen is an abundant constituent element in water, biomass, and fossil hydrocarbons. The greenhouse gas intensity (and other environmental impacts) of hydrogen production depends on the sources and processes through which the hydrogen is derived. It can be extracted from water using electrolysis, using power from renewable solar or wind, nuclear energy, or fossil energy. It can be extracted from renewable biomass or coal using high temperature gasification. Alternatively using chemical catalysts, it can be derived from renewable biogas, renewable ethanol or methanol, or fossil natural gas. Today, most hydrogen is derived from fossil natural gas, emitting fossil carbon dioxide as a by-product.
Hydrogen is an abundant constituent element in water, biomass, and fossil hydrocarbons. The greenhouse gas intensity (and other environmental impacts) of hydrogen production depends on the sources and processes through which the hydrogen is derived. It can be extracted from water using electrolysis, using power from renewable solar or wind, nuclear energy, or fossil energy. It can be extracted from renewable biomass or coal using high temperature gasification. Alternatively using chemical catalysts, it can be derived from renewable biogas, renewable ethanol or methanol, or fossil natural gas. Today, most hydrogen is derived from fossil natural gas, emitting fossil carbon dioxide as a by-product.
How does a Fuel Cell Work?
Hydrogen atoms enter a fuel cell at the anode where a chemical reaction strips them of their electrons. The hydrogen atoms are now "ionized," and carry a positive electrical charge. The negatively charged electrons provide the current through wires to do work. If alternating current (AC) is needed, the DC output of the fuel cell must be routed through a conversion device called an inverter.
Oxygen enters the fuel cell at the cathode and, in some cell types (like the one illustrated above), it there combines with electrons returning from the electrical circuit and hydrogen ions that have traveled through the electrolyte from the anode. In other cell types the oxygen picks up electrons and then travels through the electrolyte to the anode, where it combines with hydrogen ions.
The electrolyte plays a key role. It must permit only the appropriate ions to pass between the anode and cathode. If free electrons or other substances could travel through the electrolyte, they would disrupt the chemical reaction. Whether they combine at anode or cathode, together hydrogen and oxygen form water, which drains from the cell. As long as a fuel cell is supplied with hydrogen and oxygen, it will generate electricity.
here to edit.
Hydrogen atoms enter a fuel cell at the anode where a chemical reaction strips them of their electrons. The hydrogen atoms are now "ionized," and carry a positive electrical charge. The negatively charged electrons provide the current through wires to do work. If alternating current (AC) is needed, the DC output of the fuel cell must be routed through a conversion device called an inverter.
Oxygen enters the fuel cell at the cathode and, in some cell types (like the one illustrated above), it there combines with electrons returning from the electrical circuit and hydrogen ions that have traveled through the electrolyte from the anode. In other cell types the oxygen picks up electrons and then travels through the electrolyte to the anode, where it combines with hydrogen ions.
The electrolyte plays a key role. It must permit only the appropriate ions to pass between the anode and cathode. If free electrons or other substances could travel through the electrolyte, they would disrupt the chemical reaction. Whether they combine at anode or cathode, together hydrogen and oxygen form water, which drains from the cell. As long as a fuel cell is supplied with hydrogen and oxygen, it will generate electricity.
here to edit.
How do Hydrogen Fuel Cells work.gif | |
File Size: | 523 kb |
File Type: | gif |
Application
Economic Benefits
Potential challenges
- High efficiency: Hydrogen powered cells are not just pollution free but are also 2 to 3 times more efficient than traditional combustion technologies. The conventional combustion based power plant usually generates electricity at efficiencies of 33-35 % while hydrogen fuel cell systems can generate electricity at efficiencies up till 60%.
- Less noise pollution: Fuel cells operate quietly in comparison to other energy sources because they have fewer moving parts.
- Energy security: Reduced dependence on other nation states for energy. Like many other countries, the United States relies heavily on foreign oil to power its transportation sector and thus, with much of the worldwide petroleum reserves located in somewhat precarious places, the United States is vulnerable to supply disruptions. With much of the worldwide petroleum reserves located in politically volatile countries, the United States and other countries are vulnerable to supply disruptions. This makes hydrogen fuel cells even more inviting since hydrogen can be produced domestically from resources like natural gas, coal, biomass etc.
- Backup Power: Acts as a source of backup power for remote locations.
- Replacing Batteries: Fuel cells can replace almost any portable application that typically uses batteries, from hand-held devices to portable generators.
Potential challenges
- Cost: Although the cost of fuel cells have decreased significantly, the cost for a fuel cell system is almost double that of an internal combustion engine
- Permitting difficulty: Meeting codes and standards requirements for the hydrogen storage required to power the fuel cell could be one of the more difficult permitting issues. The gaseous hydrogen storage systems typically have to meet separation distances specified in NFPA 2 Hydrogen Technologies Code 2011 edition. These separation distances can be difficult to meet for hydrogen storage systems located on relatively small plots of land. For example, for a gaseous hydrogen storage system, the separation distance from the lot line can be up to 45 feet.