Scientists mimic essence of plants' energy storage system

Jul 31, 2008
A snapshot showing the new, efficient oxygen catalyst in action in Dan Nocera's laboratory at MIT. Credit: MIT/NSF

In a revolutionary leap that could transform solar power from a marginal, boutique alternative into a mainstream energy source, MIT researchers have overcome a major barrier to large-scale solar power: storing energy for use when the sun doesn't shine.

Until now, solar power has been a daytime-only energy source, because storing extra solar energy for later use is prohibitively expensive and grossly inefficient. With today's announcement, MIT researchers have hit upon a simple, inexpensive, highly efficient process for storing solar energy.

With Daniel Nocera's and Matthew Kanan's new catalyst, homeowners could use their solar panels during the day to power their home, while also using the energy to split water into hydrogen and oxygen for storage. At night, the stored hydrogen and oxygen could be recombined using a fuel cell to generate power while the solar panels are inactive. Graphic / Patrick Gillooly, MIT

Requiring nothing but abundant, non-toxic natural materials, this discovery could unlock the most potent, carbon-free energy source of all: the sun. "This is the nirvana of what we've been talking about for years," said MIT's Daniel Nocera, the Henry Dreyfus Professor of Energy at MIT and senior author of a paper describing the work in the July 31 issue of Science. "Solar power has always been a limited, far-off solution. Now we can seriously think about solar power as unlimited and soon."

Inspired by the photosynthesis performed by plants, Nocera and Matthew Kanan, a postdoctoral fellow in Nocera's lab, have developed an unprecedented process that will allow the sun's energy to be used to split water into hydrogen and oxygen gases. Later, the oxygen and hydrogen may be recombined inside a fuel cell, creating carbon-free electricity to power your house or your electric car, day or night.

The key component in Nocera and Kanan's new process is a new catalyst that produces oxygen gas from water; another catalyst produces valuable hydrogen gas. The new catalyst consists of cobalt metal, phosphate and an electrode, placed in water. When electricity — whether from a photovoltaic cell, a wind turbine or any other source — runs through the electrode, the cobalt and phosphate form a thin film on the electrode, and oxygen gas is produced.

Combined with another catalyst, such as platinum, that can produce hydrogen gas from water, the system can duplicate the water splitting reaction that occurs during photosynthesis.

The new catalyst works at room temperature, in neutral pH water, and it's easy to set up, Nocera said. "That's why I know this is going to work. It's so easy to implement," he said.

'Giant leap' for clean energy

Sunlight has the greatest potential of any power source to solve the world's energy problems, said Nocera. In one hour, enough sunlight strikes the Earth to provide the entire planet's energy needs for one year.

James Barber, a leader in the study of photosynthesis who was not involved in this research, called the discovery by Nocera and Kanan a "giant leap" toward generating clean, carbon-free energy on a massive scale.

"This is a major discovery with enormous implications for the future prosperity of humankind," said Barber, the Ernst Chain Professor of Biochemistry at Imperial College London. "The importance of their discovery cannot be overstated since it opens up the door for developing new technologies for energy production thus reducing our dependence for fossil fuels and addressing the global climate change problem."

'Just the beginning'

Currently available electrolyzers, which split water with electricity and are often used industrially, are not suited for artificial photosynthesis because they are very expensive and require a highly basic (non-benign) environment that has little to do with the conditions under which photosynthesis operates.

More engineering work needs to be done to integrate the new scientific discovery into existing photovoltaic systems, but Nocera said he is confident that such systems will become a reality.

"This is just the beginning," said Nocera, principal investigator for the Solar Revolution Project funded by the Chesonis Family Foundation and co-Director of the Eni-MIT Solar Frontiers Center. "The scientific community is really going to run with this."

Nocera hopes that within 10 years, homeowners will be able to power their homes in daylight through photovoltaic cells, while using excess solar energy to produce hydrogen and oxygen to power their own household fuel cell. Electricity-by-wire from a central source could be a thing of the past.

Source: Massachusetts Institute of Technology

Explore further: New type of solar concentrator desn't block the view

add to favorites email to friend print save as pdf

Related Stories

Secrets of the first practical artificial leaf

May 09, 2012

A detailed description of development of the first practical artificial leaf — a milestone in the drive for sustainable energy that mimics the process, photosynthesis, that green plants use to convert ...

'Artificial leaf' makes fuel from sunlight (w/ video)

Sep 30, 2011

Researchers led by MIT professor Daniel Nocera have produced something they’re calling an “artificial leaf”: Like living leaves, the device can turn the energy of sunlight directly into a chemical ...

'Artificial leaf' moves closer to reality

Jun 13, 2011

An important step toward realizing the dream of an inexpensive and simple "artificial leaf," a device to harness solar energy by splitting water molecules, has been accomplished by two separate teams of researchers ...

Recommended for you

Image: Testing electric propulsion

5 hours ago

On Aug. 19, National Aviation Day, a lot of people are reflecting on how far aviation has come in the last century. Could this be the future – a plane with many electric motors that can hover like a helicopter ...

Where's the real value in Tesla's patent pledge?

6 hours ago

With the much-anticipated arrival next month of electric vehicle manufacturer Tesla's Model S to Australian shores, it's a good time to revisit Tesla's pledge to freely share patents. ...

New type of solar concentrator desn't block the view

21 hours ago

(Phys.org) —A team of researchers at Michigan State University has developed a new type of solar concentrator that when placed over a window creates solar energy while allowing people to actually see through ...

Asian inventions dominate energy storage systems

22 hours ago

In recent years, the number of patent applications for electrochemical energy storage technologies has soared. According to a study by the Technical University Munich, the largest volume of applications is ...

User comments : 46

Adjust slider to filter visible comments by rank

Display comments: newest first

David_M
3.3 / 5 (10) Jul 31, 2008
People can already get power from solar panels by day and store it in a lead-acid battery to get power at night. Energy storage has always been the problem, hopefully trhis technology can provide a solution.
thales
4 / 5 (14) Jul 31, 2008
@ David:
The problem with batteries is that they are very inefficient; my guess is this system is more efficient by an order of magnitude or more.

@Googleplex:
The storage and distribution of H2 are valid points, but the difficulty involved is not new and is close to being overcome, as evidenced by the tentative mass production of hydrogen fuel-cell cars by Honda and others, and the availability of hydrogen as fuel in some parts of the world (e.g. southern California). As far as the expense of platinum, it's worth noting that palladium is far more expensive but is commonly used as a catalyst in catalytic converters.

What I think is exciting is this sounds simple enough to be able to reproduce the experiment at home or school!
GaryB
2 / 5 (12) Jul 31, 2008
I think what he did is split oxygen inexpensively from water. That leaves H2 or some ionic form thereof. From there, you have to split that ion and then you have H . After that step, you can use the H to make any liquid fuel that you want.

It's the liquid fuel that can be burned or used to drive a fuel cell. The liquid stores your energy output in a dense transportable form.
tpb
3.4 / 5 (18) Jul 31, 2008
Order of magnitude?
Let's not get too carried away.
Solar cell 20% efficient.
Electrolosis probably < 50% efficient.
The article doesn't give efficiency.
Pumps and motors to compress the gasses for storage are probably < 50% efficient.
Fuel cell for home < 50% efficient.
Only high temperature fuel cells even reach 50%.
0.2 * 0.5 * 0.5 * 0.5 = 2.5% overall efficieny.

So at 1KW per sq. meter at noon you will get 25 watts stored and used from the sun.
Roj
2.6 / 5 (8) Jul 31, 2008
More engineering work needs to be done to integrate the new scientific discovery into existing photovoltaic systems


Integration with solar water heaters seems simpler than photovoltaic cells competing for the same roof space.
NeilFarbstein
1.5 / 5 (19) Jul 31, 2008
Platinum is very expensive. That system in not practical.
WeAreGods
3.3 / 5 (13) Jul 31, 2008
Excuse me goobleplex, but did you finish reading the article before becoming Mr.Skeptical? They are not talking about distributing hydrogen. They said "Electricity-by-wire from a central source could be a thing of the past." As far as storing hydrogen being difficult. Sure, but it's getting easier. I'd bet storing hydrogen wouldn't be much worse than mining coal, shipping coal to a power facility, burning the coal to create the energy, and finally transmitting the electricity over many, many miles while losing energy all along the way. Eliminating centralized energy plants would mean great things for this country...e.g. protection from blackouts. And when battery and fuel cell tech takes hold, there's no way our current electricity output can even come close to powering America's automobile fleet.
Gregori
4 / 5 (14) Jul 31, 2008
Platinum is very expensive. That system in not practical.


Yet they put it into millions and millions of cars...
David_M
4.5 / 5 (14) Jul 31, 2008
Platinum may be expensive but if it is only used as a catalyst then it wont be used up in the reaction, so it wont have to be replaced.
tpb
3.3 / 5 (12) Jul 31, 2008
Another article says MIT researches claim nearly 100% efficiency in splitting water to hydrogen and oxygen, this alters my previous comment to:

0.2 * 0.5 * 0.5 = 5% overall efficiency.

So at 1KW per sq. meter at noon you will get 50 watts stored and used from the sun.
jwflowersii
4.2 / 5 (10) Jul 31, 2008
According to this article, this discovery eliminates the need for Platinum in the reaction!

http://arstechnic...rgy.html
malapropism
4.1 / 5 (9) Jul 31, 2008
And in addition, the guy mentioned in this article does not appear to have any major problems with local storage of the hydrogen he generates for use in his fuel cells. While we don't all have the amount of outdoor space he has for his storage facility, it is at least a valid proof-of-concept for household hydrogen storage.

Oh, and by the way, before anyone objects that his system was *way* too costly for it to ever become commonplace technology, note that the $500k price tag for it was in 2006 prices for the various components (mostly the 56 PV panels, I'm sure). It is now much less costly, according to the article, even without the new technology improvements mentioned in this PhysOrg article and other articles here and elsewhere.

http://www.sciam....en-house
nano999
3.9 / 5 (12) Jul 31, 2008
@NeilFarbstein - Have you ever heard of platinum in automobile catalytic converters? Did you even read the article? Another useless comment from Farbstein.
DoctorKnowledge
4 / 5 (14) Jul 31, 2008
This could be of great importance for Mars and other space colonization. Splitting water was always on the books, cost wasn't even considered a major issue: it has to be done. Existing processes don't compare to the cost of boosting a pound of H or O from Earth to Mars. But if that process on Mars were simple and low-cost...
NeuroPulse
4.1 / 5 (7) Aug 01, 2008
The cost of these catalyst materials is about 1/1000 that of platinum.

Will this make this the cheapest method of production of hydrogen and oxygen for rocket fuel?
Pogsquog
2.4 / 5 (16) Aug 01, 2008
This article is unscientific drivel.
Doug_Huffman
3.4 / 5 (7) Aug 01, 2008
Solar Constant is 1350 W m^-2
eagleapex
3.3 / 5 (6) Aug 01, 2008
I had an idea that the "missing link" in alternative energy was this sort of hydrogen from solar tech. I'm really glad to see that someone has made it happen. This will make me dislike hydrogen fuel cell cars less now.
michaeloder
3.2 / 5 (6) Aug 01, 2008
Could this use the Goretex electrode from Dr. Winter-Jensen's research as a replacement for the platinum?
http://www.physor...749.html
lengould100
2.1 / 5 (7) Aug 01, 2008
Agree with Doug Huffman. I think the article is written about a bunch of arts majors doing "Cargo Cult Science".
SLam_to
3.9 / 5 (8) Aug 01, 2008
On the platinum issue, sure platinum is expensive, but this this system probably uses very small amounts. They use platinum to coat the edges of rasor blades to keep them sharp, but they're still cheap. So it all depends on the amount you use.

More importatly, isn't the article artificually linking solar PV-cells with this new electrolosis method? From my understanding of the article this just improved the electrolisys efficienty, seems like you could use any voltage source.
D666
4.8 / 5 (6) Aug 01, 2008

More importatly, isn't the article artificually linking solar PV-cells with this new electrolosis method? From my understanding of the article this just improved the electrolisys efficienty, seems like you could use any voltage source.


Good point. This is also a shot in the arm for wind power, for instance, which suffers the same "not always available" problem as solar.

In addition, for those who are still attached to the grid, you could charge up your "batteries" at night using cheaper electricity, and run off them during the day.
googleplex
4.9 / 5 (9) Aug 01, 2008
Charge/discharge efficiency of lead acid battery:
70%-92%
Note that the lead acid battery normally does not produce explosive gases.
Producing O2 and H2 gas is an added safety/storage issue. Storing H2 gas and O2 gas is not a trivial matter like piling up coal. You need compressors and steel containers. Compressing gas requires work and generates heat from the change in entropy. Think of having a a mini propane bottling plant at home.
Here in the USA you are required to have a medical reason to be allowed "residential" O2 cylinders.
googleplex
4.7 / 5 (6) Aug 01, 2008
I envisage that it would be like having propane at home instead of natural gas. A tank in the yard piped to the house for heating. There is an established propane distribution infrastructure. I am not sure about compressing the O2 and H2. Does anyone have 1st hand experience of what it takes?
Photovoltaics is progressing with Moores law so fossil fuel competitive $/W will be achieved soon.
I am hopefull for invention of a nano electric battery/capacitor for electrical energy storage. This would make storing gas appear old fashioned and bulky.
kfong
2.6 / 5 (5) Aug 01, 2008
Battery storage aside from inefficiency has the consequence of hazardous materials and waste to be disposed of. This type of simple energy storage is exactly what we need to harness the simplicity of the sun's energy and reduce our emissions and toxic waste. Our capture technologies are also improving and I hope this type of storage will be applied to large scale thermal solar plants as it will be a long time before each individual energy consumer will have their own solar unit. If they really want to get this technology off the ground and widely used, they should look into endorsing and passing Prop 7 which will change the way California generates electricity. Check it out, www.solarandcleanenergy.org.

holoman
1.2 / 5 (11) Aug 01, 2008
To think of this technology as a source of reliable energy for the US is laughable.

Use solar during day and bateries at night, naw.

Environmental pollution from batteries and their byproducts would add to the speed we are killing our planet, i.e. the people who live here.

Here is one that will do.

http://www.p2pnet...ry/16477
MattJ
3.3 / 5 (4) Aug 01, 2008
Why does the article refer to a need for two catalysts? Once you have used the first, new catalyst to separate oxygen from water, why do you need a separate catalyst for hydrogen? Where did the H2 go from the H2O?
D666
4.8 / 5 (6) Aug 01, 2008
To think of this technology as a source of reliable energy for the US is laughable.

Use solar during day and bateries at night, naw.


Did you even read the article? Go back and read for comprehension this time. Look for any reference to batteries being needed. Doofus.
superhuman
4 / 5 (6) Aug 02, 2008
I fail to see any breakthrough in all that marketing crap talk.

Current electrolysers are very cheap and easy to do - just stick two wires into water and you've got yourself one. They also don't require any specific pH.
http://www.wikiho...se-Water

Maybe there are some specific reasons why such simple electrolysis wont work but they should have been put into the article instead of a bunch of lies.

Finally it has NOTHING to do with the way plants store energy since they store it in energetic organic compounds not as an oxygen and hydrogen (they do split water to harvest energy from the sun but not to store it).
deatopmg
4.5 / 5 (2) Aug 02, 2008
Order of magnitude?
Let's not get too carried away.
Solar cell 20% efficient.
Electrolosis probably < 50% efficient.
The article doesn't give efficiency.
Pumps and motors to compress the gasses for storage are probably < 50% efficient.
Fuel cell for home < 50% efficient.
Only high temperature fuel cells even reach 50%.
0.2 * 0.5 * 0.5 * 0.5 = 2.5% overall efficieny.

So at 1KW per sq. meter at noon you will get 25 watts stored and used from the sun.


2.5% same as plants!!!!!

About 20 yrs ago NASA people developed a brilliant energy storage scheme for solar using Fe(II)/Fe(III)and Cr(III)/Cr(II) solutions. The efficiency was ~70% if I remember correctly but the chromium II/III would drive the EPA crazy because of the posibility of it escaping into the environment and being oxidized to Cr(VI) a potent carcinogen. The neat thin was that for more energy storage all one needed was larger storage tanks (4).
gopher65
4.7 / 5 (3) Aug 02, 2008
I'd like to point out that 90% of the worlds entire supply of Platinum (which is tiny in the first place) is in one small country: South Africa. That isn't a big deal as long as no CRITICAL industries rely on Platinum, but I'd be might afraid of placing huge strategic importance on that metal. All it would take is one bomb in one mine, and poof, worldwide shortage.

That's an even worse idea than using a product (oil) that is mainly concentrated in several different countries.
Soylent
5 / 5 (1) Aug 02, 2008
@ David:
The problem with batteries is that they are very inefficient


Efficiency was never the problem of batteries. Regular lead-acid batteries are 70% efficient, NiCad 70-90%, Nimh 70%, lithium-ion batteries upwards of 90%, vanadium redox 70-80%.

The problem was and continues to be cost, energy density and durability.

my guess is this system is more efficient by an order of magnitude or more.


Hydrogen fuel cells are typically less than 50% efficient; making it a less efficient storage method than any battery technology in use.
Soylent
4 / 5 (4) Aug 02, 2008
Maybe there are some specific reasons why such simple electrolysis wont work but they should have been put into the article instead of a bunch of lies.


Electrolysis of pure water is very slow. The electrode material won't last very long unless you choose something relatively inert like stainless steel or platinum.

Care must be taken when choosing an electrolyte so that the anion has a lower standard electrode potential than hydroxide, or you won't get any oxygen(e.g. if you use Cl- you'll get chlorine gas instead of oxygen. This is not a bad thing if chlorine gas is captured and put to use). The cation must have a greater electrode potential than H , or you'll reduce it instead and get no hydrogen gas.

Sodium hydroxide, potassium hydroxide and sulfuric acid are the usual candidates for electrolysis of water.
goldengod
1.4 / 5 (9) Aug 02, 2008
I find it annoying that this website persistently markets the idea that splitting hydrogen is only possible with industrial grade technology. Just do a quick search on you tube and you will see there are very many examples of people producing their own hydrogen and hh0 at home with very simple circuits.

It's sad that the editors on this site allow this myth to persist. Hydrogen production is easy, efficient and scalable right now. The only reason we don't have it being rolled out is the damage it would do to the consumer oil industry.

However this advance in understanding is very good news as we could use solar to generate the hydrogen and rain to replenish the supply of water. That makes pretty much unlimited power available to anyone with half a brain and a bit of spare cash.
goldengod
1 / 5 (5) Aug 02, 2008
To save some time check out http://yeswaterisfuel.com
Soylent
5 / 5 (8) Aug 03, 2008
Why does the article refer to a need for two catalysts? Once you have used the first, new catalyst to separate oxygen from water, why do you need a separate catalyst for hydrogen? Where did the H2 go from the H2O?


Hydrogen ions.

I find it annoying that this website persistently markets the idea that splitting hydrogen is only possible with industrial grade technology.


Efficiency and durabillity matters.

Just do a quick search on you tube and you will see there are very many examples of people producing their own hydrogen and hh0 at home with very simple circuits.


There is no such thing as HHO.

Just do a search on youtube and you'll find people talking to ghosts, demonstrating how to heal people with crystals and communicating telepathically with dolphins.

Sparkygravity
4 / 5 (1) Aug 03, 2008
you can use silver as a catalyst at the sacrifice of efficiency
phlipper
4.5 / 5 (2) Aug 04, 2008
I fail to get excited about solar water splitting. I get very excited about nuclear water splitting. We're talking hydrogen production at a rate of several orders of magnitude greater than PV methods. To provide enough hydrogen for vehicles of the near future, I see no viable alternative to nuclear. I'm trying very hard to see the excitement of the article. Someone, please help me.
Cyril
2 / 5 (4) Aug 04, 2008
I'll help you. Some people are biased. In fact most are biased. That's why people ignore entropy and talk about how wonderful hydrogen can be. Even Nocera ignores entropy. That's because he's an idiot and MIT should fire him.

It's a bit like jumping off a 1000 meter cliff without a parachute and talking about how exciting that would be, and how wonderful the view would be.

"gravity? kinetic impact? what's that? No, that's not a problem. You see we'll make our own laws of physics to suit our biases."

Good luck luck with that, 'scientists', but I want nothing to do with it.
CaptSpaulding
5 / 5 (1) Aug 04, 2008
From the article:
Nocera hopes that within 10 years, homeowners will be able to power their homes in daylight through photovoltaic cells, while using excess solar energy to produce hydrogen and oxygen to power their own household fuel cell. Electricity-by-wire from a central source could be a thing of the past.


This is a little (massive understatement) over the top kind of comment. I'm sure tbp's estimate is high, especially when you have to bring in the reliability of the system to make it possible to mass market it. Combine all of this together and I can probably see a handful of technology demonstrator condos and houses manufactured in 5-10 years using sometype of this technology (assuming that they can get the necessary permits to store the oxygen and hydrogen, both being MAJOR fire hazards, while the O2 isn't technically flammable, many organics readily combust when exposed to that high of a level of oxygen). The likely hood of this eliminating the HOUSEHOLD power grid *might* happen in 50 years, but I SERIOUSLY doubt that industry (and electric cars) will be able to run without some additional help from sometype of large scale power generation. This system looks like it is going to cost almost as much as the average house costs, so it's likely to be largely irrelavent for the near future.
GBogumil
not rated yet Aug 04, 2008
why eliminate the grid. That just increases the potential for individual failure. Instead move to a power sharing system. If you need more than you produce the it comes from your neighbors, if you produce more, then it goes to them. Keeps existing infrastructure in use. Keeps reliability up (while you wait for a repair person). And how much are you really losing by getting or giving energy a couple houses over by wire?
Soylent
not rated yet Aug 04, 2008
If you need more than you produce the it comes from your neighbors, if you produce more, then it goes to them.


If your neighbour isn't producing power you won't either; weather is extremely well correlated on such small scales.

In order for this approach to work you need to greatly expand the grid to provide significant export/import capacity across several states/countries.
tpb
3 / 5 (2) Aug 04, 2008
Sorry Googleplex, Moore's law has nothing to do with Solar cells and never will.
Moore's law has to do with shrinking feature geometry, allowing more transistors per area.
This doesn't help for solar cells.
Its unlikely we will ever be able to affordably get more than a factor of two increase in efficiency over existing cells, although the price may come down.



holmstar
4.2 / 5 (5) Aug 05, 2008
This article confused me when I read it, so I found a better article elsewhere.

To clarify... The discovery here is about electrolysis, not solar energy. The discovery is a new catalyst for the oxygen side of the cell that is 90% more efficient than those used currently (platinum). Not only that, but the new catalyst does not require highly corrosive electrolytes for efficient operation, thus a less robust container may be used to house the reaction. Also the new catalyst is cheap. Previously both the oxygen and hydrogen sides of the cell used platinum as a catalyst, but now platinum is only used for the hydrogen side.

Current maximum efficiency for a electrolysis/fuel cell is around 50%, for a total efficiency of 25%. With the new catalyst there is an efficiency of 95%, for a total efficiency of about 90%. This, of course, ignores pressurizing the hydrogen for storage (oxygen can be vented) but the real news here is the increase from 25% to 90%.

So in summary:
H2O electrolysis cells and hydrogen fuel cells can each be 95% efficient by using a new catalyst for the O2 side.
These same cells are also cheaper to build due to:
- Non corrosive electrolyte = simple materials for the cell housing.
- Less platinum used as a catalyst
googleplex
not rated yet Aug 05, 2008
Sorry Googleplex, Moore's law has nothing to do with Solar cells and never will.


Interested in your data source?

Here is an article from the hacks at IEEE. http://blogs.spec...tra.html
I am not alone with thinking there is a similarity.
Gen_Curious
not rated yet Aug 05, 2008
Has anyone actually read the full text of what was printed in Science? And understand it?

How much platinum is needed ? a few microns of electroplated platinum can't be that expensive.