July 31, 2008
MIT Advance In Electric Power Storage

MIT researchers have developed a better catalyst for using electricity to split water into oxygen and hydrogen. Later the hydrogen can be burned to produce heat and electricity.

CAMBRIDGE, Mass. -- 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.

I think the rhetoric here is a little overblown. More obstacles remain. We still need better ways to store hydrogen. Granted, it is easier to store hydrogen in a stationary tank than in a tank in a car since the stationary tank is less constrained by weight or size or need to handle jolts and vibration. So I would like to hear more about the economics of stationary hydrogen storage. Plus, we need cheap and reliable fuel cells for burning the hydrogen to make electricity in the night.

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.

But what efficiency can we expect? 50% efficiency doubles the cost. 25% efficiency quadruples the cost. The ultimate efficiency of this process is not mentioned in the articles I can find about this research. Efficiency losses in generation of hydrogen, storage, and in the burning of hydrogen to make electricity all boost the cost of the ultimately desired night time electric power.

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.

Current costs of photovoltaics mean there's not enough photovoltaic generation capacity to make storage worthwhile. So we also need much cheaper photovoltaics. But that looks like it is in the pipeline if the claims of First Solar about their photovoltaics production costs are correct.

This does not provide an immediate solution. But the remaining engineering work all looks very solvable.

There's also still much engineering work to be done before Nocera's catalyst is incorporated into commercial devices. It will, for example, be necessary to improve the rate at which his catalyst produces oxygen. Nocera and others are confident that the engineering can be done quickly because the catalyst is easy to make, allowing a lot of researchers to start working with it without delay. "The beauty of this system is, it's so simple that many people can immediately jump on it and make it better," says Thomas Moore, a professor of chemistry and biochemistry at Arizona State University.

Thanks to Jill and Brock for the heads up.

Share |      Randall Parker, 2008 July 31 10:24 PM  Energy Solar

David Govett said at July 31, 2008 11:21 PM:

One bonus will be decentralized power generation, which will do for the power grid what the Internet does for the telecom system: increase its robustness.

Finnsense said at August 1, 2008 1:17 AM:

I don't think hydrogen storage is a problem. As you say, it's storing it cheaply enough where there are size and weight constraints that is the problem. If battery technology continues to improve or if a holy grail technology like the Eestor pans out, the stored energy can just be used to recharge the car battery.

The timeframe given is ten years and we can expect plenty of competitive solar in that timeframe. Maybe not as cheap as coal but still easily affordable and many people would be willing to pay a bit more for a) control of their power supply and b) an environmentally friendly alternative. If they can produce enough energy to power their electric or hybrid car then that becomes really economical too, since gas is so expensive.

philw1776 said at August 1, 2008 7:26 AM:

Why not also consider using the solar energy to make high energy liquid fuels for transport? CH4 and hydrocarbon flex fuels.

NancyU said at August 1, 2008 8:56 AM:

Is it Christmas?

Today Randall brought us this post on a breakthrough which brings us the potential for cheap solar powered hydrogen and a post on "exercise in a pill". Thanks for the presents Randall!

I'm going to feel good all day.

dave.s. said at August 1, 2008 10:22 AM:

"..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.. am I missing something? How in the Hell can you make oxygen gas from water and not have hydrogen appear, too?

Brock said at August 1, 2008 11:51 AM:

Dave S, the initial process produces hydrogen ions. The second process combines them into neutral H2 gas.

Randall, this EE Times article claims "almost 100-percent efficiency." What that really means isn't clear to me. Does that mean the fuel cell produces "nearly 100%" of the power as it took to create the H2 gas in the first place?

Joe said at August 1, 2008 12:47 PM:

I still don't get it. When you use current electrolysis techniques to produce H2 (like the do it yourself video on the internet), are you also producing pure O2 gas? If not, what? If so, how do you get pure H2? Some separation mechanism?

Nordic said at August 1, 2008 1:28 PM:

Better yet you could use this process to store cheap off-peak power from nuclear plants to meet peaking demand during the day. I would much rather see that than to risk my neck installing and maintaining pv cells on my roof, plus it must be cheaper to have a few large hydrogen storage and combustion facilities rather than a hydrogen tank in every backyard.

Nick G said at August 1, 2008 3:10 PM:

"if the claims of First Solar about their photovoltaics production costs are correct."

Well, First Solar is publicly traded. If their photovoltaics production costs are incorrect then so are their profits, and that's serious defrauding of investors.

I think we can believe them.

Re fuel cells: Perhaps the most important remaining problem would be the cost of stationary fuel cells. Has anyone seen any cost figures per MW of generating capacity?

Fat Man said at August 1, 2008 8:50 PM:

Here is the EETimes article.

I haven't the vaguest idea of what the claim of almost 100% efficiency is supposed to mean in the context of electrolysis. Clearly, it does not mean that you can get final products out of the process that contain more energy than you put into the process. That being the case, the real impact of this claim is minimal. It does not change the fact that the sun only shines half the time.

Furthermore, there must be energy losses in the electrolysis process. Current does not flow through the process without resistance. Resistance produces heat, which is a loss of energy.

A complete solar energy system would have to be specified with a solar electric generating system (pick your favorite thermal or PV) and a storage system. Say we use this new electrolysis system as part (note PART) of the storage system. We still have to store the hydrogen and oxygen that are produced, and then turn them back into electricity. Pipes, pumps, tanks, generators (take your pick gas turbines or fuel cells) etc. all cost money. I would bet on gas turbines here because the Oxygen does not help fuel cells that much.

This does not make hydrogen a plausible transportation fuel. The problems of storage and transmission are not affected.

Randall Parker said at August 1, 2008 9:05 PM:


Glad to make you happy. Yes, this is really a good news day. I haven't even gotten around to posting about recent advances in Alzheimer's treatments.

dave.s., Joe,

Yes, the press release and press coverage are confusing. I think the advance here is that the catalysts can be made more cheaply. Maybe there's an efficiency advance as well.


Given a cheap way to store electric power then nuclear power can be made more cheaply than photovoltaics 10 years from now then nukes will have a chance to provide not just baseline but also peak power as well. But will nuclear power be able to compete?

Tom said at August 5, 2008 5:53 PM:

Just tossing out random thoughts here, but is the ability to store electricity from solar panels really all that interesting at this juncture? I guess if the vast majority of your electricity comes from solar, then OK. But we're pretty far from that. I thought we had a very sizable excess of electrical generation capacity during the night, with daytime capacity getting stressed. So all we need solar to do is ease the load during the day, when the sun is shining. No better battery than the electric grid. Won't that take us decades into the future before it's better to save the electricity for use at night instead of first easing off the dirty/limited daytime generation?

Or am I missing something here ?

Lee said at August 5, 2008 6:40 PM:

I think Tom is right regarding this application. As long as you are connected to the grid (as the vast majority are) the air conditioning loads in the sunnier climates will easily demand all the solar. There are lots of hydro-electic reserves that can more easily be modulated to correct for over-production during the day. Also, don't get confused, splitting water always results in the same proportion of hydrogen and oxygen - H2O. But they are saying that most of the energy is lost at the oxygen side of the reaction - and this catalyst addresses that. Also, comments regarding fuel cells are correct - they are expensive - and so is platinum by the way (the "easy" H2 electrode) and Fuel cells will incur loss as well. This is not to down play the invention itself, only perhaps the speculated application. I suspect the Navy, on the other hand, and NASA will be very interested in this for oxygen generation in submarines and space-craft. If you in a Nuclear sub for a few months, there's no shortage of electricity, or water, but not so much air. As is often the case in the USA, I suspect the DoD will be the driving force behind developing this one.

Randall Parker said at August 7, 2008 7:45 PM:


MIT is spinning this advance as especially helpful for solar electric power. But any way to more cheaply store electric power for use at a different time has application regardless of whether the electricity is generated by solar, wind, nuclear, or even coal.

Some day photovoltaics will be far cheaper. Then this advance will especially matter for photvoltaics. But PV has to drop a lot in price and this advance has to get translated into a cheap and reliable technology. We are still years away from those two things both happening.

Basil said at March 11, 2009 12:28 AM:

Search "hho torch" on youtube and "Fresnel lens steam"

Put together the torch replaces the fresnel lense!! Steam generator!!

Richard McIver said at November 2, 2011 3:34 PM:

Storeage (solar and wind) is not as important as once thought. In Europe solar and wind
is used, lets say solar during day, when demand is high (day) and solar available and 7% less
line losses is great. The grid is the battery with users using solar electricity and
night maybe nuclear or hydro. It seems storeage is not that necessary as many sources and
many providers unless you are off-grid.

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