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PEOPLEWATCH:
The Fantastic Catalyst

What will be the oil of the future? According to Dan Nocera, water plus light. That’s it.

07/2008

Interviewed by Charles Linn, FAIA

MIT Professor Daniel Nocera has spent the last 30 years attempting to duplicate what plants do so efficiently: using solar energy to split water into oxygen and hydrogen. The process of electrolyzing water is nothing new—most of us did it in junior high science class. But, what plants do that humans cannot is to separate the two efficiently, using very little electrical energy, and only earth-abundant materials. Now, Nocera believes his lab may well have created a catalyst that does just that. If his invention passes rigorous scientific review, it would constitute a major breakthrough.

MIT Professor Daniel Nocera
MIT Professor Daniel Nocera
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GreenSource: You’ve said that without major breakthroughs, the alternative energy sources we’re staking the future on can’t possibly meet the world’s needs.

Daniel Nocera: Here is what we’re up against: Right now the world is using about 12.8 terawatts—a terawatt is a trillion watts—and most of that is from fossil fuel. By 2050 the world will be using, minimally, 30 terawatts. So we need to come up with roughly 18 terawatts of clean energy to stay even. Okay, so let’s say I plant every square foot of land on earth with crops. I’m going to take that and make fuel out of it—we will be using none of that for food, mind you, and, by the way, we don’t have catalysts to convert cellulose to ethanol yet. That gets me seven terawatts. Then let’s add nuclear. A plant puts out a gigawatt, so I need 8,000 nuclear plants. That’s one plant opening every two days for the next 42 years. I need some significant technical breakthroughs there, too. Nuclear yields eight terawatts, for a total of 15 terawatts. I’m almost there. So, now, let’s cover all the land on earth with wind turbines, and that gets me two terawatts. Then, dam all the rivers on earth that are left to be dammed, and I get a terawatt. Now I’ve got my 18 terawatts. Okay, so no more eating, there are dead birds all over the place, the ecosystems of all the rivers are destroyed, and I’ve just eked it out.

GS: It sounds grim.

DN: Well, it is and it isn’t. Over the past couple of centuries, just as our energy supplies have been about to give out, some technical breakthrough has changed the game. Whale oils were the fuel for awhile. Just as the whales were about to go extinct in the 19th century, Abraham Gestner figured out how to distill kerosene from oil. This time, we’re the whales, and we need to come up with a breakthrough so we don’t become extinct. The answer has got to be the sun. The sun bathes the earth in 800 terawatts. All you need are 30 of them. What people haven’t been able to do is take that solar energy and efficiently split it into hydrogen and oxygen. That’s artificial photosynthesis. If you could do that, then you could store the sun’s energy. I look over at the MIT pool and that’s 3.2 million gallons of water, and if I split that it can hold 43 terawatts.

GS: Yes, but it’s not very efficient.

DN: Right! We’ve been electrolyzing water our whole lives. But we do it in such a lousy way. There are big transmission losses, and it’s really costly. We can do hydrogen, but nobody’s been able to duplicate the leaf and get the oxygen out. That’s the really tough part of the problem. No one has been able to make a synthetic catalyst that has been able to duplicate photosynthesis out of a glass of water. Now we have! On January 10, here in the lab, we made a catalyst that makes oxygen out of a glass of water under very benign conditions using a bare minimum of electricity. The catalyst is made of earth-abundant materials, and it’s cheap as hell. That’s a real door opener. When you put it in a glass of water, add a current, the oxygen just starts bubbling out of it.

GS: But I thought everyone was trying to make hydrogen. Why do you need the oxygen?

DN: Good question. If you take just the hydrogen, most of the stuff you have left over is called hydroxide. It’s useless. You need the oxygen so you can burn the hydrogen with it or use it to make electricity with a fuel cell. If you don’t have the oxygen, you can’t have a closed loop; you have to keep adding water and disposing of the hydroxide—in that case, it’s not renewable. But we’re not making hydrogen. We’re just rearranging the chemical bonds in the water. Remember, hydrogen isn’t energy. It stores energy. If your house were covered with PV, you would make much more electricity than you can use. That’s why people sell their electricity back to the grid, because they can’t store it. What I’m doing is taking that extra energy and storing it as hydrogen.

GS: Don’t you need a lot of PV?

DN: If PV has 10 percent efficiency, the U.S. would need about the same amount of area as is now covered by our roadway system. But I do not suggest we should cover Arizona with PV. You do that, and you’re taking this discovery and putting it in a stupid system again. This energy will be distributed. Your home will become a power station. For your house, you are talking about managing about two gallons of water. All of the sudden you can start to say, “Wait a minute, I can see an entire world made of this stuff.”

GS: What was it like when you saw the catalyst work the first time?

DN: It was not a nirvana moment. The first thing a scientist asks is, how is this thing going to screw me? When is the other shoe going to drop? So we ran control experiments, and they worked. Now we are submitting a paper for publication, and other scientists basically will try to attack it in order to help me. They are going to be really brutal. In research, you have to be so impartial and so analytical. There are lots of crusaders in science, because you can convince yourself of anything. Well, that’s a really slippery slope. Once I sense I’m starting on a crusade, I bring myself into the back room and slap myself around, because that’s when I stop being a good scientist.

GS: It’s a great discovery.

DN: We can have all the policy people, the economics people, all the engineers taking stuff and engineering the hell out of it and doing their projections—and all of a sudden you can just throw it all out the window with one great discovery. Is it the final discovery? We’re not sure. But when people learn what we’ve done and how we did it, they are going to have lots of great ideas. The community is really going to run with this.That’s the power of science.

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This article appeared in the July 2008 print issue of GreenSource Magazine.

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