ENVT 200 03

Using Seawater to Make Hydrogen Fuel

A new device capable of producing an alternative type of energy that doesn’t release CO2, and uses only sunlight and seawater has been created. Assistant professor Daniel Esposito and his team at Columbia Engineering created this floating prototype, capable of generating hydrogen gas (H2) in a very sustainable way.

Hydrogen gas is a zero-emission form of energy. When burned, it only produces water. However for nearly all the processes that make hydrogen fuel, carbon dioxide is often released into the atmosphere, only contributing to global warming, and making other forms of green energy the safer options. Esposito and his team were interested in finding a way to use water electrolysis (the separating of water into hydrogen and oxygen gas) to make hydrogen without CO2 also being an end product. They ended up creating a device called a floating photovoltaic (PV) electrolyzer. It is currently still a small prototype, but it has the potential to develop into a complex, larger scale device. Ideally, the end product would float on the ocean, looking very similar to a deep-sea oil rig, and would produce H2 using only the seawater and sunlight. This prototype is different from others of its kind because it doesn’t use membranes to separate hydrogen and oxygen. In other devices, the membranes separating the gases are vulnerable to the microorganisms and other debris found in seawater.

The device works by relying on a “unique configuration of electrodes that separate and collect hydrogen and oxygen gas, based on the buoyancy of their bubbles in water.” This means that the device doesn’t require any pumping of liquid, while still producing a nearly 99% pure hydrogen fuel. Although the design isn’t quite ready for open-ocean operations yet, it has been tested in the lab, and it’s very likely that the team will begin to improve the design so that it is eventually able to perform on much larger scales.

I really enjoyed reading this article because I am not very knowledgeable on energy sources, and I was able to learn a lot just by reading about this new device. Upon further research, I found that hydrogen fuel is cheaper than gasoline, typically better for the environment, and even more efficient than gasoline. With these points in mind, I think it’s very important that developments are made on the prototype soon, so that these devices can be used frequently, all over the world. My only possible concern is what exactly happens with the seawater used by the device, is this water continuously being absorbed by the device, and if so, how much water are we using in order to make H2?

I think the author was intending this article to be read by a large variety of individuals, most specifically people with knowledge on energy and engineering topics. I don’t believe the author had any bias or agenda to go along with his article, other than his want to educate people on new, greener energy, and the amazing innovations Esposito and his team were able to apply to the device. I think it’s amazing that we have so many great minds working on products like this that continue to give us options for energy sources, especially when CO2 emissions are reduced.


“The stand-alone PV-electrolyzer prototype floating in sulfuric acid, left, compared to a rendering of a hypothetical large-scale “solar fuels rig” operating on the open sea.”
– Jack Davis; Justin Bui/Columbia Engineering

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