Mar
22
Separate Cells For Hydrogen and Oxygen In Water Splitting
March 22, 2017 | Leave a Comment
American Technion Society researchers have developed a new method for safely and efficiently producing hydrogen using separate cells for the hydrogen and oxygen. The new technology is expected to significantly reduce the cost of producing the hydrogen and shipping it to the customer.
The researchers at Technion are developing a photoelectrochemical (PEC) cell that utilizes solar energy to split water into hydrogen and oxygen directly, without the need for an external power source.
The team set out to solve three major hydrogen challenges: Keeping the hydrogen and the oxygen separate from each other, collecting the hydrogen from millions of PEC cells, and transporting the hydrogen to the point of sale.
The Technion team solved these challenges by developing a new method for PEC water splitting. With this method, the hydrogen and oxygen are formed in two separate cells – one that produces hydrogen, and another that produces oxygen. This is in contrast to the conventional method, in which the hydrogen and oxygen are produced within the same cell, and separated by a thin membrane that prevents them from intermixing and forming a flammable and explosive mixture.
The diagram shows the technology developed at the Technion: the oxygen and hydrogen are produced and stored in completely separate cells. According to Ms. Landman, one of the electrodes (anode) can be replaced by a light sensitive electrode (photo-anode), so that the conversion of water and solar energy into hydrogen fuel and oxygen will be carried out directly in each compartment simultaneously. Image Credit: American Technion Society. Click image for the largest view.
The new process allows geographic separation between the solar farm consisting of millions of PEC cells that produce oxygen exclusively, and the site where the hydrogen is produced in a centralized, cost-effective and efficient manner. They accomplished this with a pair of auxiliary electrodes made of nickel hydroxide, an inexpensive material used in rechargeable batteries, and a metal wire connecting them.
Avigail Landman, a doctoral student in the Nancy & Stephen Grand Technion Energy Program explained, “In the present article, ‘Photoelectrochemical Water Splitting In Separate Oxygen and Hydrogen Cells’ published in Nature Materials, we describe a new method for producing hydrogen through the physical separation of hydrogen production and oxygen production. According to our cost estimate, our method could successfully compete with existing water splitting methods and serve as a cheap and safe platform for the production of hydrogen.”
This is not the whole of the technology, as noted previously, the vision of the Technion researchers is geographic separation between the sites where the oxygen and hydrogen are produced: at one site, there will be a solar farm that will collect the sun’s energy and produce oxygen, while hydrogen is produced in a centralized manner at another site, miles away.
Thus, instead of transporting compressed hydrogen from the production site to the sales point, it will only be necessary to swap the auxiliary electrodes between the two sites. Economic calculations performed in collaboration with research fellows from Evonik Creavis GmbH and the Institute of Solar Research at the German Aerospace Center, indicate the potential for significant savings in the setup and operating costs of hydrogen production.
In October, Ms. Landman won first place in the energy category in the Three Minute Thesis competition held in Australia. At the competition, held on the initiative of the University of Queensland, participants are required to present groundbreaking research in just three minutes. Watch Ms. Landman’s presentation below:
Avigail Landman – Technion, Israel Institute of Technology – Photoelectric Chemical Water Splitting: A Renewable Path from Three Minute Thesis (3MT®) on Vimeo.
The method developed at the Technion for separating hydrogen production and oxygen production was the basis for the development of new two-stage electrolysis technology. This technology, which was developed by Dr. Hen Dotan from the Electrochemical Materials & Devices Lab, enables hydrogen production at high pressure and with unprecedented efficiency, thus significantly reducing hydrogen production costs. The new technology is now in its pre-industrial development stage.
This is highly interesting concept that is reported to be working. If the electrodes are holding a comparably large store of hydrogen and the release can be regulated, this team may be on to something huge. Perhaps the electrodes themselves can be sold / exchanged and used as fuel canisters that consumers can defuel as needed, The possibilities are awe inspiring!
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