UC Berkeley Web Feature
Growing energy: Berkeley Lab's Steve Chu on what termite guts have to do with global warming
BERKELEY – For most scientists, winning a Nobel Prize is the culmination of a lifetime of research and experimentation. A Nobel Laureate could easily be forgiven for resting on such laurels. But Steven Chu, director of the Lawrence Berkeley National Laboratory since 2004, was only 49 when he shared the 1997 Nobel Prize in Physics for codeveloping ways to cool and trap atoms using lasers. And to hear him tell it, he has several more careers ahead of him.
A self-described "academic black sheep," Chu's insatiable intellectual curiosity long ago made up for a somewhat slow start. In addition to atomic physics and laser spectroscopy, he has immersed himself in polymer physics and biology. Along the way, he has also acquired a new mission: challenging scientists to find environmentally friendly energy alternatives to fossil fuels. A speech he made at an Institute of Physics conference in April made headlines for its radical premise that this quest is the century's single most important scientific endeavor - and for Chu's suggestion that termite guts could point to a possible solution. The NewsCenter paid a visit to Chu in his Berkeley Lab office to discuss the future of the world's fuel supply, what termite guts and manure piles can teach us, and why we shouldn't be writing off nuclear energy.
Why did you leave Stanford University, which you've called "a rich and wonderful place"?
I knew Berkeley Lab was a great lab, with a wonderful opportunity to do even greater things in the future, including with energy. That was a major reason. There was also a more selfish, personal one: I had been a professor at Stanford for 17 years, and although I could easily have continued there, I've always changed fields every five or six years. I thought I'd also like to do other things.
Other than physics?
Sure. I used to sculpt when I was young. I love writing, and I wouldn't mind writing books. I love teaching freshmen as well as graduate students. I have a long list of things I'd like to do someday.
I believe you have some work to do first. What's led to what some have called your "crusade" to find carbon-neutral sources of energy for the world?
First of all, I'm not alone in this. For me, it has been a gradual awakening over the last five or six years - a growing realization that global warming is a serious problem. At the Lab, a number of people were increasingly looking at this as one of the major problems that science and technology have to solve. There was already a groundswell, and so when I came in and started talking about it, it wasn't as though I had to convince a lot of people.
There are stronger and stronger indications that global warming is happening, that it's caused by humans, and its consequences are looking more and more ominous. You can draw a parallel to the early days of [research into] cigarette smoking, the '50s and '60s, where scientists said, "Hey, there seems to be a link between lung cancer and cigarette smoking."
And in this case the link is between burning fossil fuels and global warming.
Right. As I said we don't know the exact consequences yet, but we can guess they're pretty serious. Take some of the current computer climate modeling simulations - which are not proof - that in the Midwest, the temperature will increase 5 to 10 degrees Fahrenheit on average. With hotter summers, that means that during the growing season, the soil moisture will decrease by 20 to 30 percent. Now, if you take that at face value, then the great agricultural machinery of the U.S. is at risk, with huge economic consequences.
OK, let's talk termites. Headlines have you saying they could save the world from its oil dependence. How?
I was misquoted. Termites aren't going to save the world, but we can learn a lot from them. The earth naturally produces a lot of biomass - plants. When that biomass rots, it produces natural gas, what's been called "swamp gas" because it was discovered in a swamp. Colonies of bacteria at the bottom of the swamp were feeding on this biomass, this dead plant debris, and turning it into methane.
'The problem with what we do now with fossil fuel is that we dig it out of the ground. It took 100 million years to make fuel deposits of that scale, and in the next 200 years, we will probably have used it all up.'
Now, if you look in the gut of a termite, or the gut of a cow - or even in feedlot manure piles - there are bacteria that are similarly converting biomass into energy for them to live on. But termites don't get to eat fruits and vegetables; they eat mostly wood. If you ate wood, you'd pass it straight through your digestive system, as would an old-time cow that eats grass instead of what they get in the feedlots these days. So, termites have developed a symbiotic relationship with colonies of bacteria that can break this stuff down. [They are not born with the microbes; they depend on other members of their colony to feed the bacteria to them periodically.] The bacteria can convert biomass that was essentially only good for burning into a different form of chemical fuel.
So do you foresee some sort of termite factory in our future?
No. Either we'll genetically engineer the microorganisms from termite guts to produce more energy from biomass than they need, or we'll adapt the chemistry within the microorganisms to process the biomass ourselves.
There's a lot of biomass out there. If we're ever going to raise crops for energy, it's not going to be for the oil we can extract from the corn or the sugar from the sugar cane that we can convert to ethanol, it's going to be for the entire biomass of the crop. If we could figure out a way of efficiently converting the biomass of a very rapidly growing plant - one that doesn't require much fertilizer or water, and that's suitable for our different geographies - into chemical fuel, that would be great. We may well enlist microorganisms to help with that conversion.
As you mentioned, feedlots - and landfills - already generate methane gas from biomass. Why don't we use that?
We should, absolutely. Feedlots are a huge supplier of methane, and it just goes up into the atmosphere.
I thought methane was a "greenhouse" gas, one that contributed to global warming?
It is, a horrible one. Methane is a natural gas, and when you burn natural gas, you make carbon dioxide. Methane's actually about 20 times worse than carbon dioxide, but it converts to carbon dioxide in the upper atmosphere eventually. The methane now being made by the bacteria in the manure piles of feedlots just escapes, so why don't we burn it for fuel? We won't have added any carbon dioxide to the atmosphere, but at least we've extracted the energy that's useful to us.
When you raise crops for energy, you're actually combining carbon dioxide with water, some nutrients, and sunlight to make a carbon-based fuel. If you burn that fuel efficiently, it's a closed cycle: you take carbon dioxide out of the atmosphere to make the fuel and burn it to release it, so the cycle just goes round and round. The problem with what we do now with fossil fuel is that we dig it out of the ground. It took 100 million years to make fuel deposits of that scale, and in the next 200 years, we will probably have used it all up. If you include coal too, it might take 400 years.
The U.S. government has spent $7 billion to come up with ways to produce ethanol, a fuel that can be substituted for gasoline but has no harmful emissions. What's wrong with the current method?
There's a vitriolic debate about that. Right now, we grow corn to produce ethanol. We convert the corn oil to ethanol, as well as the corn stalks, cellulose, and other biomass. The debate is over whether that process is break-even in terms of energy invested in versus energy out, whether it's carbon-dioxide neutral.
Meaning we're able to produce more fuel from corn than the amount of fossil fuels it took to grow the corn?
Yes. Corn requires a lot of fertilizer, and fertilizer nowadays is made from either petroleum or natural gas. It's been estimated by one report that 25 percent of the energy input to corn is fertilizer. Then there's the diesel fuel to drive the tractors, gasoline for the trucks that distribute it, the whole works. Sunlight is free, but all the other things you have to do to convert corn to fuel have to be measured against the energy you can ultimately get out to burn for electricity or to put into cars.
The U.S. Agriculture Dept pays people a lot of money not to grow crops on their land. As one person said, "Look around, we can't really eat more" - or we shouldn't, anyway. If we have land we're not using, we should be growing our fuel — in a way that doesn't consume a lot of resources. We could increase the efficiency of how we use land, water, and input energy in the form of fertilizers, harvesting and distribution energy, and the energy required to convert biomass into a more usable chemical fuel. If we increase our efficiency factor by two or three, we could easily use half our agricultural capacity to grow energy. Guess what? That would mean we wouldn't be depending on the rest of the world for energy, especially petroleum: there would be all sorts of benefits.
Should fission-based nuclear power plants be made a bigger part of the energy-producing portfolio?
Absolutely. Right now about 20 percent of our power comes from nuclear; there have been no new nuclear plants built since the early '70s. The real rational fears against nuclear power are about the long-term waste problem and [nuclear] proliferation. The technology of separating [used fuel from still-viable fuel] and putting the good stuff back in to the reactor can also be used to make bomb material.
And then there's the waste problem: with future nuclear power plants, we've got to recycle the waste. Why? Because if you take all the waste we have now from our civilian and military nuclear operations, we'd fill up Yucca Mountain. [Yucca Mountain, which sits on federal land in Nevada , is under consideration as a long-term storage facility for spent nuclear fuel.] So we need three or four Yucca Mountains. Well, we don't have three or four Yucca Mountains. The other thing is that storing the fuel at Yucca Mountain is supposed to be safe for 10,000 years. But the current best estimates - and these are really estimates, the Lab's in fact - is that the metal casings [containing the waste] will probably fail on a scale of 5,000 years, plus or minus 2. That's still a long time, and then after that the idea was that the very dense rock, very far away from the water table will contain it, so that by the time it finally leaks down to the water table and gets out the radioactivity will have mostly decayed.
Suppose instead that we can reduce the lifetime of the radioactive waste by a factor of 1,000. So it goes from a couple-hundred-thousand-year problem to a thousand-year problem. At a thousand years, even though that's still a long time, it's in the realm that we can monitor - we don't need Yucca Mountain.
And all of a sudden the risk-benefit equation looks pretty good for nuclear.
Right now, compared to conventional coal, it looks good - what are the lesser of two evils? But if we can reduce the volume and the lifetime of the waste, that would tip it very much against conventional coal.
Last question. What kind of car do you drive?
Oh no. In my defense - well there's no defense. A Lexus. Mostly I bike to work. I used to drive it where I filled it up maybe five times a year. I drove it so little that I had to get a constant battery tickler, unfortunately now I drive it more than that. There's some home pressure. I want to buy a hybrid, but my wife doesn't want me to buy a Prius, and I don't want to buy a Lexus hybrid because I don't want to drive an SUV even if it's a hybrid SUV. In the next couple of years I hope there will be something in between, and I'll buy that.
- "Worldwide Energy Crunch: Power to the people — and how to keep it coming," editorial by Steve Chu, San Francisco Chronicle, July 17, 2005
- Chu's home page at Berkeley Lab
- Chu's autobiography on the Nobel Prize website