Proton Exchange Membrane Fuel Cells
Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
The United States consumes a large amount of energy – the current rate is around 97.5 quadrillion BTUs annually. The vast majority (90%) of this energy comes from non-renewable fuel sources. This energy is used for electricity (39%), transportation (28%), industry (22%), and residential/commercial use (11%). As the world has a limited supply of these non-renewable sources, the United States (among others) is expanding the use of renewable energy sources to meet future energy needs. One of these sources is hydrogen.
Hydrogen is considered a potential renewable fuel source, because it meets many important criteria: it’s available domestically, it has few harmful pollutants, it’s energy efficient, and it’s easy to harness. While hydrogen is the most abundant element in the universe, it is only found in compound form on Earth. For example, it is combined with oxygen in water as H2O. To be useful as a fuel, it needs to be in the form of H2 gas. Therefore, if hydrogen is to be used as a fuel for cars or other electronics, H2 needs to be made first. Thusly, hydrogen is often called an “energy carrier” rather than a “fuel.”
Currently, the most popular way to make H2 gas is from fossil fuels, through steam reforming of hydrocarbons or coal gasification. This does not reduce dependence on fossil fuels and is energy intensive. A less-used method is by electrolysis of water. This also requires an energy source, but it can be a renewable source, like wind or solar power. In electrolysis, water (H2O) is split into its component parts, hydrogen gas (H2) and oxygen gas (O2), through an electrochemical reaction. The hydrogen gas made through the process of electrolysis can then be used in a Proton Exchange Membrane (PEM) fuel cell, generating an electric current. This electric current can be used to power motors, lights, and other electrical devices.
1. Using the Electrolyzer to Produce Hydrogen Gas
- Setup the electrolyzer (Figure 3).
- Set up the gas collection cylinders, making sure the distilled water level in the outer cylinder is at the 0 mark (Figure 4).
- Connect the electrolyzer to the gas collection cylinders (Figure 5).
- Connect a solar panel to the electrolyzer using jumper wires and expose to direct sunlight (Figure 6). Note, if the weather is not coope
During the electrolysis procedure, hydrogen and oxygen gas are generated once the solar panel is connected and exposed to sunlight. It takes approximately 10 min to generate enough H2 gas to fill the inner cylinder (Table 1). Note that there is twice as much H2 generated as O2, as seen in the balanced equation:
2 H2O(l) → 2 H2(g) + O2(g)
Onc
Hydrogen is a flexible fuel. It can be produced on-site in small quantities for local use or in large quantities at a centralized facility. The hydrogen can then be used to produce electricity with only water as a byproduct (provided a renewable source of energy, like a wind turbine, was used to generate the hydrogen gas). For example, in Boulder, Colorado, the Wind2H2 project has wind turbines and solar panels connected to electrolyzers that produce hydrogen gas from water and then stores it to be used in their hydrogen
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