Breakthrough produces Hydrogen Fuel from Seawater
Hydrogen is the most abundant element in the universe. As a fuel, hydrogen burns clean producing only water vapor as a byproduct, and contains large amounts of energy. The Space Shuttle used hydrogen as a fuel, in its massive external tank, to blast into orbit. Now, a breakthrough may allow for the clean production of hydrogen fuel from the most abundant resource on Earth – seawater.
Extracting hydrogen from water is nothing new. It’s a simple process known as electrolysis. Using electricity, the positive Oxygen atoms in H2O are attracted to the negative electrode. Conversely, the negative Hydrogen atoms are attracted to the positive electrode. In this way, water can be separated into hydrogen gas and oxygen gas.
Credit: Tyler Henderson
The hydrogen gas can then be used in a variety of ways to produce energy. It can be used to boil water in a power plant, instead of using coal or natural gas.
It can be combined with oxygen to produce power in a fuel cell (battery). These are in use today on the space station. Hydrogen fuel can even be used in current automobile engines instead of gasoline.
Technical Hurdles to Success
There are 2 primary technical hurdles to obtaining enough hydrogen to make it a widely available fuel source.
First, is the electricity needed for electrolysis. It doesn’t make sense to use electricity from a coal powered plant, for example, to produce hydrogen to be used to power another plant. The solution is to use solar, wind, or wave energy to power the separation process.
In a way, the hydrogen produced is basically storing the solar, wind or wave energy that produced it. This also solves the current issue with how to store, for example, solar energy for use when the sun is not shining.
The second technical hurdle is the salt in the sea water. Unless the salt is removed before electrolysis, the chloride ions in seawater turn into toxic chlorine gas, which degrades the equipment and seeps into the environment. This desalination process is expensive.
Fortunately, research scientists at Penn State appear to have solved this issue. They have developed a design for a seawater electrolyzer. It uses an electric current to split apart the hydrogen and oxygen in water molecules, but also incorporates a membrane which first removes the chloride ions.
“Hydrogen is a great fuel, but you have to make it,” said environmental engineer Bruce Logan. “The only sustainable way to do that is to use renewable energy and produce it from water. You also need to use water that people do not want to use for other things, and that would be seawater. So, the holy grail of producing hydrogen would be to combine the seawater and the wind and solar energy found in coastal and offshore environments.”
The thin, semipermeable membrane that the team is using was originally developed for purifying water in the reverse osmosis treatment process. Using high pressure on the water, it is pushed through the membrane, leaving the salt behind.
The team’s test results were published in Energy & Environmental Science. If they are successful in their continued development of a system, it could literally change the world.
“The world is looking for renewable hydrogen,” Logan said. “For example, Saudi Arabia has planned to build a $5 billion hydrogen facility that is going to use sea water. Right now, they have to desalinate the water. Maybe they can use this method instead.”
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