24 August 2013

Artificial photosynthesis hits milestone in producing cheap, clean hydrogen from water

A decade ago hydrogen fuel cells seemed like the next big thing, but they never got past the concept stage for one important reason — producing hydrogen is hard. While it’s true that hydrogen is the most common element in the universe, most of it is bundled up out of our reach in stars and nebulae. All the methods of producing hydrogen on Earth are less than ideal, but one company thinks it’s on the right track with so-called artificial photosynthesis. HyperSolar is working to develop a solar-powered system to split water into hydrogen and oxygen, and it just reached an important milestone — tantalizingly close to feasibility.

Hydrogen is of interest because it can be a very efficient energy storage and transport medium, and there is no negative impact from harvesting that energy. Hydrogen fuel cells produce water vapor as a byproduct. That’s vastly preferable to the cocktail of carbon dioxide and fine particulates that result from burning fossil fuels.

There are two ways to produce usable volumes of hydrogen, and they both have serious drawbacks. The hydrogen atoms can be split off of fossil fuels, which are simply long hydrocarbon molecules. This is how most hydrogen is produced right now because it’s very cheap, on the order of $1-2 per kilogram, but it rather defeats the purpose of clean energy. The second option is more intriguing — the electrolysis of water can split H2O into hydrogen and oxygen. However, it takes a lot of juice to break the bonds in water, so you get less energy out than is put in.

That’s where HyperSolar comes in. The California-based company thinks it can crack the code on hydrogen production with a solar-powered electrolysis solution. It would essentially take energy from the sun, and use only that to split water molecules and harvest the hydrogen. This would have advantages over traditional solar power because the hydrogen produced would store energy much more efficiently than batteries, which are notoriously slow to improve.

HyperSolar is not the first company to chase this lofty goal. Sun Catalytix seemed to be on the right track to develop artificial photosynthesis a few years ago, but abruptly abandoned the project after deciding the economics were not favorable. Its method could produce hydrogen at a cost of $6.50 per kilogram — much higher than the hydrocarbon method. Meanwhile, HyperSolar is working with very low-cost panels to improve the economics, and it has just crossed the important 1 volt threshold.

You need 1.5 volts to realistically split water molecules, and HyperSolar has been improving its system at a startling rate. It was only 8 months ago that HyperSolar’s very inexpensive solar cell technology was only putting out 0.2 volts. Three months ago it reached 0.75 volts, which makes for a rapid increase in efficiency when the new 1 volt number is figured in.

HyperSolar’s technology is based on a proprietary nanoparticle that integrates photovoltaics bonded to chemical catalysts to generate hydrogen. The company seems convinced it will reach 1.5 volts without a large increase in cost. HyperSolar has chosen to make much of its development process public. Is that confidence, or overconfidence? Time will tell.

Now read : Carbyne: A new form of carbon that’s stronger than graphene.


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