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New record energy efficiency for artificial photosynthesis

A new world-record 22 percent conversion efficiency for solar-powered hydrogen production has been claimed by researchers from Australia's Monash University
A new world-record 22 percent conversion efficiency for solar-powered hydrogen production has been claimed by researchers from Australia's Monash University
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A new world-record 22 percent conversion efficiency for solar-powered hydrogen production has been claimed by researchers from Australia's Monash University
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A new world-record 22 percent conversion efficiency for solar-powered hydrogen production has been claimed by researchers from Australia's Monash University

As the world moves towards developing new avenues of renewable energy, the efficiencies of producing fuels such as hydrogen must increase to the point that they rival or exceed those of conventional energy sources to make them a viable alternative. Now researchers at Monash University in Melbourne claim to have created a solar-powered device that produces hydrogen at a world-record 22 percent efficiency, which is a significant step towards making cheap, efficient hydrogen production a reality.

Efficiency records for solar-powered hydrogen production have continued to rise over the years, and much more rapidly as the technology and techniques improve. Even as late as December last year Gizmag reported a solar-driven hydrogen record efficiency at the time of just 12.3 percent, so this new record shows a very healthy 10 percent improvement on that and beats out the previous record of 18 percent.

Splitting water using electricity to produce hydrogen and oxygen has been an established scientific technique for many decades. However, the rate at which hydrogen has been produced in this way has not been commercially viable due to the relatively low conversion rates compared to the input energy costs. Ideally, solar-powered water-splitting would be one of the best ways to produce hydrogen as its energy input cost is effectively zero.

On the downside, however, the low efficiencies of past solar devices have kept this technology largely in its infancy. The Monash researchers believe that may all soon change as increased efficiencies in the process and in the devices themselves improve.

"Electrochemical splitting of water could provide a cheap, clean and renewable source of hydrogen as the ultimately sustainable fuel." said Professor Leone Spiccia from the School of Chemistry at Monash who led the research. "This latest breakthrough is significant in that it takes us one step further towards this becoming a reality."

According to the researchers, the breakthrough is significantly attributable to the leading-edge capabilities of the group in which they work and a growing expertise in tuning the processes and materials used in water splitting.

To help achieve the required solar-input efficiencies, the team utilized the very best commercial-grade multi-junction (indium gallium phosphide, gallium arsenide, and germanium) solar cells available to ensure the maximum sunlight to electricity conversion.

However, an even greater contribution to efficiency was on the material side, where the use of expanded foam nickel electrodes increased the available electrolysis surface area with such efficiency that the electrolyte in which they were immersed was simply local river water with the addition of a standard pH buffer (generally a salt solution containing sodium phosphate and sodium chloride).

In this combination of high-efficiency cells and high-yield electrodes, the team claims the 22 percent record for conventional solar-cell to electrochemical production of hydrogen.

What the eventual limit of such technologies is a largely moot point at this stage and largely reliant on the increasing efficiency of solar-cell light conversion factors. Advances in such things as perovskite solar-cells may assist in this regard and, compared to some other methods of sunlight-powered water-splitting yet to fully prove their mettle, may achieve the necessary breakthrough point to tip the balance in favor of cheap, abundant hydrogen fuel.

"Hydrogen can be used to generate electricity directly in fuel cells," said Professor Doug MacFarlane, ARC Laureate Fellow and leader of the Energy Program of the ARC Centre of Excellence for Electromaterials Science at Monash. "Cars driven by fuel cell electric engines are becoming available from a number of car manufacturers. Hydrogen could even be used as an inexpensive energy storage technology at the household level to store energy from roof-top solar cells."

The results of the research were recently published in the journal Energy and Environmental Science.

Source: Monash University

7 comments
andyfreeze
I can see short term hydrogen storage, a battery if you like, being rolled out As a power source. You can use all sorts of renewable power generators to generate hydrogen on the spot to be used later to generate power when the renewables are ineffective ie night time or no wind. Efficiency over a certain point is irrelevant. For transportation however, batteries seem a better proposition. The infrustructure is almost there for batteries but would require an enormous amount of resources to get hydrogen to the same point. Not to mention that converting to hydrogen, storage and burning hydrogen for electricity is relatively inefficient compared to batteries. You have to appreciate the confines of a car and the compromises that entails. Tesla cars and soon other makes is a testament to what i say. Each has a strategic place.
Reason
Surely rather than focussing all attention on efficiency (yes, still a worthy goal for scientists), a simple cost equation should be developed. Consumer rooftop PV has reached a level where there must be tens of millions of households that often produce excess with minimal feedback tariffs even for those still grid connected. The question is at what point it becomes economic to create and store hydrogen instead of battery backup ... and also fuel the car. I'd happily double the number of panels we have if we could do both.
Yukonite
An efficiency increase from 12.3% to 22% is an increase of 9.7 percentage points, or an efficiency increase of 78.9%. This is somewhat more impressive that the 10% mentioned in the article.
DanielWilliams
Its a good thing the oil industry got round to cleaning up this mess. But they're not completely to blame, at least they're keeping the economy unstable too.
Scott in California
andyfreeze, for heating a domicile, domestic hot water, or for cooking, I don't think hydrogen can be beat. No exhaust gases, other than water vapor. And, usable at night time.
TheTimeTraveller
Extremely well written article, and interesting topic. Amazing.
Mickomarvel
So, the most efficient solar cells are around 24% efficiency, then you have a 22% efficiency converting that electricity to hydrogen and, at best, about 45% efficiency converting that hydrogen into mechanical energy. Now, 0.24 x 0.22 x 0.45 = 0.02376, or in plain talk about 2.4%, overall efficiency. Still a long way to go, I'm afraid.