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.

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.

Daniel Nocera describes new process for storing solar energy
Video: MIT News Office/AMPS

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.

The project is part of the MIT Energy Initiative, a program designed to help transform the global energy system to meet the needs of the future and to help build a bridge to that future by improving today's energy systems. MITEI Director Ernest Moniz, Cecil and Ida Green Professor of Physics and Engineering Systems, noted that "this discovery in the Nocera lab demonstrates that moving up the transformation of our energy supply system to one based on renewables will depend heavily on frontier basic science."

The success of the Nocera lab shows the impact of a mixture of funding sources — governments, philanthropy, and industry. This project was funded by the National Science Foundation and by the Chesonis Family Foundation, which gave MIT $10 million this spring to launch the Solar Revolution Project, with a goal to make the large scale deployment of solar energy within 10 years.

Josec65  - From a Hydrogen fan 2009-09-28 08:49:47
Hello Mr. Nocera on your comments you talk about using your H2 generator on fuel cells, what about internal combustion engines like: spark ignition engines, jet engines, or stirling cycles?
green20680  - Responce to Josec65 2009-09-29 06:01:11
Did you have a responce to this inquiry?
Bill Lauderdale  - Hydro ATB 2009-10-05 05:28:22
We are working on developing an articulated tug and barge for use as a marine highway alternative.

The barge design has voids that can be used to house fuel cells producing power for the electric tug engine.

Most ports have large warehouse structures that could accomodate solar panels and provide power for hydrogen production.

Do you think you system can be scaled to this larger use?
TechRich  - Why not ammonia? 2009-10-23 11:53:43
Hydrogen stored at 345 bar (5k psi) yields 3.27 MJ per liter.
Ammonia stored at 10 bar (145 psi) yields 13.49 MJ per liter - 4.1 times the density!
Why not store excess electricity as ammonia?
BillWilliamm  - Congratulations Dr. Nocera 2010-07-07 05:34:07
Hi Dr. Nocera, This may a great leap in weaning ourselves from Carbon based fuels.Some of the other commenter's need to read the article more closely. Why not internal combustion engines,ICE. The best efficiency possible from an ICE is something less than 50%. By using co-generation we have achieved 60% and we may be able to improve on that. A fuel cell can convert fuel to electricity at about 90% efficiency. No contest. The early NASA fuel cells were just carbon, graphite, and would work fine for stationary applications. They would also be cheap compared to fuel cells that use expensive catalysts. They are too bulky for automotive use.
aca  - hi 2010-11-23 04:54:16
large amounts of hho can be compressed within lithium 6 deuteride.
mgorske  - next step 2009-11-09 04:55:52
Finally someone came up with this! And hopefullly it can be cheap and easy enough for third world countries also.
But the next step is carbon sequestration - like the plants do, they add carbon dioxide to the hydrogen to form more stable organic compounds that can be saved in greater quantities than is used - just like the days of the dinosaurs.
adamstjohn  - Danger? 2009-11-16 04:54:39
Suppose tons of complementary levels of hydrogen and oxygen are stored in buildings across the world.

A spark sounds dangerous.
jamescondren 2009-11-16 18:08:24
What about internal combustion engines like: spark ignition engines, jet engines, or stirling cycles?
James Norton  - I Volunteer 2009-11-24 04:58:13
My ears perked up during last week's Science Friday broadcast regarding this research. This technology is right up my alley. I am off the grid since '94, here in Mass, deep in the forest, with my own pond. Please bring this to market (or demo) faster than the the 8ish years. I am tired of replacing lead acid batteries.
IAEngineer  - Residential Fuel Cells NOW! 2009-12-13 15:50:07
The current off-the-grid movement combined with the increased security of de-centralized power systms will hopefully push development of economical, small scale solar-powered hydrogen fuel cells. Tapping into that massive amount of enegry hitting the planet everyday seems like a no-brianer.
How can we help this happen sooner rather than later?
archer717  - none 2009-12-28 04:48:18
Good but not good enough, Professor Nocera. What we really need is direct generation of H2 from sunshine, i.e., photo-lysis, not electro-lysis of H2O. Photosynthesis splits the H from the H2O molecule but the C in CO2 grabs the H leaving us with nothing but O2 and carbs. Mind you, I'm not complaining, O2 is nice (and, so far, free), but why can't we persuade those photons to give us free H2 so we can skip the electric (via photovoltaic or other means) step? Isn't this possible?
BillWilliamm  - Dangerous? 2010-07-07 05:34:35
Hi archer717, Hydrogen is lighter than air so it will rise and vent to the atmosphere. What if we store gasoline in buildings all over the world? Gasoline vapors are heaver than air and stay on the ground just waiting for a spark or pilot light. The real limit to a hydrogen economy may be the cost of the piping and handling equipment. Hydrogen will pass through many materials and damage them, like steel and other metals. Almost pure chrome works but as demand goes up so will the price.
dandy 2010-11-22 05:22:28
When H2 is used in Stirling engines as the working fluid, they seed it with about 2% CO2 which finds it way in between the metal atoms and effectively seals it and prevents the loss of the H2.
archer717  - none 2009-12-28 04:48:52
1. What is efficiency of this process, i.w., what is the ratio

efficiency = caloric value of H2 produced per kWhr of electrical input.

2. TechRich asks Why not ammonia? NH3 is not itself a fuel so I presume one can produce H2 from NH3 fairly easily. But how? TechRich doesn't bother to tell us.

If he sees this, i hope he will tell us.

hammer  - color 2010-03-15 05:23:22
if all the light on the electrode are absorbed, the color of the electrode should be black. but on the photo the color on it is not black.
lampasas  - whats the benefit 2010-01-05 05:30:12
article does not nor any of the other newsy articles on this really do not describe the expected benefit. water still takes the same amount of energy to be split so where are the savings? has the team acheived some remarkable increase in the efficiency of the process? the overwhelming cost of solar through PV to electrolosis and then to hydrogen, is the PV system - the electrolosis is just a small part of the process
EIS  - amp spikes 2010-01-13 09:20:21
What this system accomplishes is not only a solution to the storage issues we have with PV but also the demand that can spike a battery backup system.

A hydrogen generator will produce energy similar to a diesel generator allowing high demand and consumption equipment like compressors and welders to be run. No current PV solution has this ability other than grid interactive netmetering.
avg  - From a Hydrogen fan 2010-01-11 04:56:22
TechRich asks Why not ammonia? NH3 is not itself a fuel so I presume one can produce H2 from NH3 fairly easily. But how? TechRich doesn't bother to tell us. AVG free download

Hello Mr. Nocera on your comments you talk about using your H2 generator on fuel cells, what about internal combustion engines like: spark ignition engines, jet engines, or stirling cycles?

Larry  - From an energy storage fan 2010-01-19 05:20:00
The storage of solar energy is a commendable objective. One searches for ways to do this in the most efficient manner. Rechargeable hydrogen oxygen devices are a very inefficient manner to do so. Even the most efficient regenerative fuel cell concepts pale in performance compared to the more tradition electrochemical devices usually called batteries. Rechargeable lithium batteries are probably the most energy efficient battery types. One of the problems presented in the MIT concept is related to the suggested use of neutral water as the electrolyte. Neutral water has a very low conductivity for ions. Commercially available devices have selected electrolytes of much higher conductivities such at potassium hydroxide solutions or acid polymer membranes. In other words, the suggested MIT concept makes very little sense when viewed against modern electochemical water electrolyzer and fuel cell technology.
rslettehaugh  - Hydrogen is the Way to GO 2010-01-31 12:59:15
Everyone should have a solar or wind hydrogen generator in the garage. They should have a hydrogen storage tank and a car converted to run on hydrogen. It's the Future. You don't need fuel cells, internal combustion hydrogen is the way to go for your car. Fuel cells might make sense for powering a home because they are quiet.
matthew002  - clean water? 2010-03-29 05:21:57
my question is, would you have to clean the water to reuse in cycles of burning in a fuel cell, contamination of metal and does it ruin the electrodes if it did. Having clean water to that level would add to the cost with equipment.
harmsworth  - late to this party 2010-05-12 05:36:19
I just tumbled to this site via another. I was not aware of this work. What I see is a possibly new way to produce oxygen from water. Interesting but we have lots of oxygen available to us and plants produce tons every second. There is only a suggestion that use of a platinum catalyst will free up hydrogen for use as a fuel. I am guessing that this is the sticky bit, either because platinum costs more than water or possibly because the PAE doesn't like to let go of the Hydrogen. And yes, Ammonia can be used as a fuel and does have superior energy storage characteristics as long as you don't mind having a toxic, explosive high pressure fuel tank.
parotin  - Congratulations 2010-05-14 13:10:45
I think Mr. Nocera's discovery is really interesting. Thanks!

This process allow us to take water from the world, break it with solar power (which means give energy to mr. oxygen and mr. hydrogen as compensation for breaking his marriage) store it, and then when we need energy, reset the couple taking back the compensation. The best is at the end of all the cycle (after we use the energy) the quantity of water is the same, and we don't increase the co2 presence.

Let's see if Chesonis Fundation, MIT and the scientifics can go on against petrol productors interests. I wish!! please, be aliens and don't allow them slow down that really needed power revolution!

Incredible: produce H at home without use carbon to do it!

Cheers world!
PanAmMan  - Algea vs PV Cells 2010-07-08 04:51:00
I have read a couple of the catalyst papers from MIT regarding the efficiency of water cracking and then the combined efficiency of storing the H2 for use at night. It seems that this is just a more efficient & Durable high capacity battery as there does not appear to be a net energy gain from the catalyst.

how does this technology compare with the high efficiency / capacity super capacitors that we expect in the next 8 years?

BillWilliamm  - Update on my errors ;) 2010-07-15 05:15:22
As usual I write first and do research later. Sorry. I have found many fuel cells have effency rates in the 60% to 80% range. Only one has a 90% effency and it has special conditions required.
Several people have ask about the water purity requirement. Any minerals in the H2O will coat the catalyst and stop the reaction. On the H2 generators I have worked with deionized water was required and a small amount of strong base was added to the first start up of the unit. After the first start up only pure water was required. As far as I know to produce pure H2 another catalyst is needed for the O reaction or the OH- will build up and release O and contaminate the H2 and start a small fire. I say small fire because all I have worked with is small H2 units to supply H2 for the gas chromatograph.

As stated by others the only reason for this method to be of any advantage is if it is much cheaper or more efficient than the present technology.

There is no reason this process could not be put into use now with current H2 generators except for the cost of fuel cells. I'll check on the cost and efficiency of Sterling engines.
Miguel Grande  - Coorstek ceramic battery 2010-07-22 12:00:12
How is this idea different from the Coorstek battery already in development?
jay  - Hydrogen Fuel Cell 2010-08-19 10:59:39
You are converting electricity (generated by PV) into a chemical reaction to separate water atoms. At night when there is no sun, you use H and O to generate electricity via Hydrogen Fuel Cell.

Just wondering how one can scientifically prove that we get the same amount of energy that we put in. I guess I am referring to the efficiency of the system.

The idea of having every household generate its own power is excellent both technically and philosophically.

I believe your research can benefit a lot if a Hydrogen Fuel Cell manufacturer invests in your project. (I am sure you have already thought of that).

arimuse  - But will this be used? 2010-08-30 04:48:58
This is wonderful research, but who will own it?!? Will the world be able to see a near future of sustained cheap energy? Or, will giant oil/electric groups snap it up so it may not be used until they run out of what they provide, or they can dole it out to the public at their price?!?

I would LOVE to run my home/auto on solar/wind right now, but it is beyond my means at over 40K for a place 1200 sf. Also, my state (SC) does not allow us to sell back energy produced in excess of useage.

If MIT could hold patents etc maybe they could actually sell to individuals and small individual energy startups and not exclusively to huge energy consortiums. Thanks.
jayaram72  - method of water splitting? 2010-09-22 04:45:49
superb work, Is it possible to for middle class families for usage this process????????
amos33 2011-02-14 05:01:32
We went to the moon in 1969 and discovered it is not made of green cheese. Where have we ventured too since?

We have millions of combustion engines that need to be utilized, OxyHydrogen can be used to enhance that combustion. A 4 cube can produce 4 liters per minute using 420 watts produced from solar panels and deep cell marine batteries linked in parallel.
das  - ? 2011-03-02 07:43:11
That's great !

what exactly this special 'cost-effective' photocatalyst ?

How much efficient is it during the day time production of the H2 and O2 ?

rajkjalan  - Commercialisation 2011-03-28 08:37:18
This morning I read in Indian newspapers that a large industrial house has signed up with the MIT for commercialization of this technology. I'm sure such developments must have taken place in other parts of the world also.

Should the institutions like MIT not make such projects OPEN PROJECTS for anyone to participate and further develop like we have Open Source Software in the larger interest of Human Race.
brahmburgers  - cost? 2011-03-28 08:34:24
granted, new technologies are always expensive initially, then cheaper if proven popular in ensuing years. Will this be boutique technology like GPS or surround-sound stereo, or will this be something simple-to-install and affordable?
ukj 2011-04-01 04:40:47
It is good to read that hydrogen and oxygen are separately being generated. What happens to the counter ion. Perhaps a reference citation will help us read and understand their work properly. We can also contribute to their effort. This work has its own importance and it would be wrong to compare photosynthesis with this work. The basic difference in photosynthesis and this work is the usage of carbon cycle and no generation of hydrogen gas. The concept in any case is fantastic once put to implementation on a pilot scale.
Angelgroove  - Hydrogen storage 2011-04-14 19:09:09
So now we are back to that proposal of safe hydrogen storage. This is where the myth hits reality. There is not a real safe way to store hydrogen and I would be alarmed at this requirement where every home is a potential bomb. It is bad enough to store gasoline in stations where 20,000 gallons represents a bomb potential now we are talking about something the PGE disaster in San Bruno would pale in comparison.

I have a breakthrough with room temperature metal based fuel cell that makes copious joules of energy. My system cannot use the waist products in gas form and are safely ejected, not stored. Much more sane, now all I need is the lab and founders to help. Interested?
plock4523 2011-04-24 15:15:00
This is indeed exciting. But it will never see the light of day. Can you imagine for one moment just how much of an impact this would have on the oil, coal and nuclear power industries. There
are people out there that stand to lose
too much money. I am not a conspiracy nut, but I would bet 1,000.00 right now that you will never see the regular folks have access to anything like this. There is a status quo that has to maintained and it will be at any cost.
This idea will be bought, patented and stored away where it can do the monied no evil. In other words it will simply disappear. I just hope the people who developed this do not disappear along with the idea.