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---------------------- 2316 - Getting hydrogen fuel from San Francisco Bay ?
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- Theoretically, to power cities and cars, you need so much hydrogen it is not conceivable to use purified water. We barely have enough water for our current needs in California.
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- Hydrogen is an appealing option for fuel because it doesn't emit carbon dioxide. Burning hydrogen produces only more water and should ease worsening climate change problems.
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- As a concept, splitting water into hydrogen and oxygen with electricity, called electrolysis, is a simple and old idea. All you need is a power source connected to two electrodes placed in water. When power turns on, hydrogen gas bubbles out of the negative cathode and breathable oxygen emerges at the positive anode.
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- Most High School chemistry labs have set up this same experiment and seen it working.
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- But negatively charged chloride in seawater salt can corrode the positive end, limiting the system's lifespan. Researchers needed to find a way to stop those seawater components from breaking down the submerged anodes.
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- The researchers discovered that if they coated the anode with layers that were rich in negative charges, the layers repelled chloride and slowed down the decay of the underlying metal.
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- They layered nickel-iron hydroxide on top of nickel sulfide, which covers a nickel foam core. The nickel foam acts as a conductor transporting electricity from the power source and the nickel-iron hydroxide sparks the electrolysis, separating water into oxygen and hydrogen.
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- During electrolysis, the nickel sulfide evolves into a negatively charged layer that protects the anode. Just as the negative ends of two magnets push against one another, the negatively charged layer repels chloride and prevents it from reaching the core metal.
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- Without the negatively charged coating, the anode only works for around 12 hours in seawater. The whole electrode falls apart into a crumble. But with this layer, it is able to go more than a thousand hours.
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- Previous studies attempting to split seawater for hydrogen fuel had run low amounts of electric current, because so much corrosion occurs at higher currents. But researchers were able to conduct up to 10 times more electricity through their multi-layer device, which helps it generate hydrogen from seawater at a faster rate.
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- Another research group has also discovered a catalyst that minimizes the production of chlorine gas during salt water electrolysis.
- In the electrolysis of salt water, such as seawater, the ultimate goal is to produce hydrogen at the cathode. The product formed at the anode is ideally oxygen, because that is harmless to the environment.
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- However, during salt water electrolysis toxic chlorine gas can also form at the anode. The researchers have now produced a catalyst that minimizes the formation of chlorine gas in favor of oxygen formation.
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- The catalyst consists of two metal oxides of iridium oxide with a layer of manganese oxide only a dozen nanometers thick. Iridium is a material that exhibits high catalytic activity for the formation of both oxygen gas and chlorine gas. The manganese oxide acts as a kind of membrane that prevents the supply of chloride ions and suppresses the formation of chlorine gas."
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- The electrolysis of water is an important step for the production and use of hydrogen as an alternative energy carrier. An anode that counteracts the formation of chlorine gas enables water electrolysis where it is not necessary to first rid the water of dissolved salt, the process of which still costs significant amounts of energy and capital. It allows the direct production of hydrogen from seawater.
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- A useful side effect of salt water electrolysis is the production of very pure fresh water. If the extracted hydrogen gas is ultimately used as fuel, for example in a fuel cell of a car, the hydrogen reacts back to water with oxygen gas from the atmosphere.
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- That way, the large-scale application of water electrolysis and hydrogen in fuel cells will lead to large quantities of this 'waste product' being pure water.
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- Most of their tests were in controlled laboratory conditions, where they could regulate the amount of electricity entering the system. But they also designed a solar-powered demonstration machine that produced hydrogen and oxygen gas from seawater collected from San Francisco Bay.
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- Without the risk of corrosion from salts, their device matched current technologies that use purified water. Electrolysis using seawater will open doors for increasing the availability of hydrogen fuel powered by solar or wind energy.
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- The technology could be used for purposes beyond generating energy. Since the process also produces breathable oxygen, divers or submarines could bring devices into the ocean and generate oxygen down below without having to surface for air.
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- Other Reviews:
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- 1477 - Hydrogen to fuel cars? Today we use plant technology to produce our Oxygen from water. Hydrogen produces 2.5 times more energy per pound than gasoline.
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- 528 - The hydrogen economy will take awhile, written in 2004. Hydrogen is the simplest and most common element in the Universe. However on Earth is is locked up in other elements , like water H2O
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- 509 - Cures for Global Warming may be hydrogen fuel.
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- March 18, 2019
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-------------------------- Wednesday, March 20, 2019 --------------------------
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