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Solar Hydrogen Company Secures $4.7M in Series A Round

Second-generation prototype Solar Hydrogen Generator with solar concentrator.

Nanoptek Corporation, a renewable energy company that produces hydrogen directly from water using sunlight and its proprietary photocatalyst, has closed a $4.7 million Series A equity financing round led by The Quercus Trust, a California fund with multiple investments in clean technology and renewable energy.

Ardour Capital Investments, LLC served as financial advisor in the transaction. Series A investors also included the Massachusetts Technology Collaborative (MTC) and private investors. With this investment, Nanoptek expects to complete the development of its field-deployable Solar Hydrogen Generator, develop pilot manufacturing capability, and install its first pilot plant for producing carbon-free hydrogen.

Nanoptek’s Solar Hydrogen Generator (SHG) produces hydrogen directly from water using only sunlight and its proprietary photocatalyst in a process known as photoelectrochemical (PEC) water dissociation, or photolysis. No carbon dioxide is produced.

In electrolysis, electricity passed between two electrodes immersed in a water and salt electrolyte dissociates the water into pure hydrogen and oxygen. Replacing one of the electrodes with a photoactive semiconductor such as titania produces hydrogen directly when illuminated with sunlight. Sunlight produces electron-hole charge pairs in the titania that break water into hydrogen and oxygen in a reduction-oxidation, or redox, reaction. However, the lifetime and efficiency of PEC technology to date has not been not commercially viable.

Nanoptek has developed an improved titania photocatalyst by developing a process that coats a thin film of titania semiconductor onto a plastic nano-structured surface that induces large local nano-scale stresses in the titania. These stresses stretch the titania crystal lattice so that electrons are held less tightly in the lattice and so can be knocked out of the titania with light of lower energy. These electrons then drive the hydrogen production.

This bandgap engineering enables Nanoptek’s titania photocatalyst to be photoactive well into the visible blue, and so is six times more efficient in sunlight than native titania, which requires the sparse ultraviolet (UV) part of the solar spectrum, according to the company.

The performance of Nanoptek’s titania improves with heat, so heat from the sun can be used to further increase the efficiency of the photolysis process, and solar concentrators can be used for better economics. The manufacturing process is scalable, low cost, and requires less energy than other processes.

The first-generation prototype in 2004 had an effective area of 0.25m2 and produced hydrogen at the rate of 3 liters/hour or 720 liters/month. Light harvest efficiency was 37% and photon conversion efficiency was 9.6%

Nanoptek developed the technology over 5 years with funding from NASA, the US Department of Energy (DOE) Office of Basic Energy Sciences, and a SEED (Sustainable Energy Economic Development) loan from the Massachusetts Renewable Energy Trust totaling over $1.3M.

Nanoptek expects to sell the carbon-free, locally-produced hydrogen to customers with high value industrial applications, and plans to also make it available for applications including transportation, backup power, electricity for municipalities, and off-grid off-pipe power generation.

Ultimately, Nanoptek envisions the possibility of “ultra-distribution” of production, where many homeowners would be able to produce most of the hydrogen required for their vehicles right at home. A rooftop area of about 50 ft by 50 ft would supply enough hydrogen for the driving needs of an average family of 4, according to Nanoptek.




They physics of this bandgap engineering are interesting. Stretching the lattice of the titania nanosheet should be applicable to other semiconductor films - increasing their photon conversion efficiency e.g. bandgap PV.


Looks like an interesting technology, unfortunately achieving a reliable product for the masses can take a long road.
There still is a major challenge to decent storage of H2 on vehicles. Gathering the H2 from all the individual ~panels, routing and combining this, compressing the H2 and storing it for in-home vehicle usage would no doubt be challenging and expensive. Can't imagine the combined safety issues of having an entire neighborhood with all this H2 equipment spread out all over their roofs.
One home system leak could trigger off a rather spectacular neighborhood event (not too bad if it is the 4th of July).
All-in-all I am happy to see the visionaries are busy at work, I'll wait a while and see how it develops before putting an H2 conversion unit on my car.


You could use the hydrogen and oxygen to increase yields of biomass gasification to methane. The oxygen can be used in the gasification process and the hydrogen can be combined with the abundant carbon to make more CH4.


They give the efficiency of the first gen prototype but give us a picture of the second gen prototype. Why? Looks very heavy & I don't think I'd want it on my roof. Especially 2,500 sq. ft of my roof. There has to be a better way.

Lou Grinzo

daverdeam: Excellent point about the energy needed to compress that hydrogen, which is more than most people typically realize.

I always tell people to Google the hydrogen papers written by Ulf Bossel, who has done some very detailed analyses of what it will take to produce, transport, dispense, and use hydrogen for transportation.



probably no less safe than neighborhoods full of natural gas lines.

Alex Kovnat

The most important thing for us to realize regarding solar energy is this: Since upwards of half of our electric power comes from burning coal, we can ALWAYS use more carbon-neutral electricity.

So if you're going to devote money and land area to solar collectors, instead of making hydrogen (which is the leakiest gas there is), one might as well use the most efficient solar cells technology can practically devise. And then, use the resulting solar electricity in lieu of electric power from burning coal.


Conversion efficiency 9.6%. Compress and transport that hydrogen and now it's 8%. Release the energy in a fuel cell and now it's 4%. I'd rather have a battery please!


Durrr, who cares what the conversion efficiency is. The sun is free dontcha know.

The important thing here is capital cost per energy unit. If that is cheap (probably not) then its all systems go.

This neatly gets round the issue of storing solar power, which to date has been by far the biggest challenge.



I don't know what "photon conversion efficiency means" but it's not equal to energy efficieny.

From, the energy content of standard temperature and pressure hydrogen is 2.7 Whr/l. So the .25 m^2 device produces 8.1 W of hydrogen engergy at noon on a clear day.

Efficiency = 8.1W (hydrogen power out)/250W (solar power in) = 3.9%.


Why not convert it to methane and store it along with the millions of M^3 of natural gas that we currently store underground. Natural gas pipelines already cross the continents of most countries and pass through sunny areas.

That way it can be quickly converted to electricity for charging our electric cars using the already in place electric grid.

I did do some work on this a while ago however the hydrogen cells never got developed - until now.


Methane conversion using biomass and this sounds good. It is easy to transport, store and we can run cars on it cleanly.


Concept, acheivement? or savior?
If H is the desired outcome then this seems quite a cedible result.
Almost blood from stone.


Consider this as a way to produce onsite a small amount of fuel 'conditioner' enough to 'spike' a few days worth of driving, where small quanities possibly in low pressure absorbents could prove usefull and larger quantities present storage problems.
The enhanced fuels may have emissions and power advantages.


Rather low efficiency.
also, the water to be split must go inside the machine, possibly destroing the catalyst. so it needs to be ultra-pure.
Moreover, it will probably be not so easy to put a few such machines on my roof.
The relatively complex mechanics of the machine will also make it rather difficult to be mass-produced and made much cheaper.

On the other hand, next-generation solar panels (like will probably be much cheaper, while having a high efficiency in electricity conversion.
(Cheaper to buy and cheaper to install.)
Even old-fashoned electrolysis of that electricy will probably produce more H2. The electrolysis can be done far from the solar panels, making it much less vulnerable to impurities in the water.
Compression of the H2 isn't necessary, since the H2 can be produced directly in high-pressure containers. So no further pumps are needed, no efficiency is lost.

When the bateries of your car are empty, you feed them with the solar electricity directly, when there is no further need for electricity, H2 is produced in a cheap electrolyser.


Who ever said that energy storage is needed for solar power? Oh, let me guess: the utilities. Firstly there is no country that is even near the point where renewables would cause grid management problems. This is why wind power, which is as intermittent as solar power, has been growing very well without energy storage. Some say that if we reach 20% of the grid then it will be a problem. BUT, research at Imperial College has shown that this might be exaggerated since the various forms of renewables (including geothermal, etc.) would compensate each other, AND grids would help equalise everything. So the energy storage thing seems to be largely a chimera for scaring off renewables.
Now let us suppose you need storage... what about conventional storage such as pumped hydro? Probably cheaper than solar hydrogen... OK not probably, definitely!
Then there is the idea of using PHEVs and BEVs to store electricity, but I won't even go there... sounds nice but also too complicated (for now).

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