Meeting The Nation's Bioenergy Goals

A federal renewable fuel standard calls for mixing 36 billion gallons of biofuels into transportation fuel by 2022. But the U.S. produces only one-third of that amount today. Ira Flatow and guests talk about meeting that goal with products like cellulosic ethanol or oil squeezed from algae.

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IRA FLATOW, host:

This is SCIENCE FRIDAY from NPR. I'm Ira Flatow.

The first tendrils of the creeping oil slick in the Gulf of Mexico are lapping against the wetlands of the Mississippi Delta, threatening many types of birds that nest and breed there. It could imperil manatees, dolphins, shellfish, plankton. I could go on with all the - you all know the marine life that lives in the Gulf.

And President Obama announced today to delay offshore drilling until some of the causes of that explosion are found, but could this potential ecological disaster have him rethinking, or have a lot of people rethinking and refocusing our efforts, like promising new biofuels?

So think about this, instead of drilling a mile undersea and then dealing with an inevitable oil spill like these, why not pump up oil pump out of algae? We can now get algae to make oil for us. We can now get electricity from bacteria. We're going to talk about that today.

We can make ethanol from tough, woody stuff that people don't eat instead of from the corn that we do eat, like the corn cobs and the stalks and the paper waste and woodchips and switch grass.

This hour, we're going to be talking about cutting-edge research into these newer alternative energies. Are they cost effective yet? You think about the billions of dollars it's going to take to clean up this oil spill and the money lost in tourism and fishing industries, maybe these alternatives become cost effective when you add these kinds of figures, these damage figures, into the mix.

What do you think? Our number 1-800-989-8255. You can also tweet us @scifri, @-S-C-I-F-R-I and go to our website at sciencefriday.com and let us know what you think about the topics - get into the discussion going on there.

Let me introduce my guests. Adam Bratis is the biofuels program manager at the National Renewable Energy Laboratory. That's in Golden, Colorado. He joins us from studios in Denver. Welcome to SCIENCE FRIDAY, Dr. Bratis.

Dr. ADAM BRATIS (Biofuels Program Manager, National Renewable Energy Laboratory): Thanks, Ira. It's a pleasure to be here.

FLATOW: You're welcome. Lee Lynd is the co-founder and chief scientific officer at Mascoma Corporation. That is a biofuel company based in Rome, New York. He's also professor of environmental engineering design at Dartmouth in Hannover in New Hampshire. Welcome to the program, Dr. Lynd.

Dr. LEE LYND (Co-founder, Chief Scientific Officer, Mascoma Corporation; Professor, Environmental Engineering Design, Dartmouth College): Thank you, good afternoon, glad to be here.

FLATOW: Thank you. Adam, how big is the biofuel market today? How much of it is replacing fuel from petroleum?

Dr. BRATIS: Yeah, the market today essentially comes from two sources, and predominately it's corn, and it's corn-based ethanol; and a smaller portion is soybean-based biodiesel. And I'd say we're at somewhere in the ballpark of nine or 10 billion gallons of ethanol produced, and you're offsetting somewhere in the ballpark of seven or eight percent of the gasoline demand in this country.

FLATOW: Is there a bigger market, a potentially bigger market for it?

Dr. BRATIS: Sure, there is. One of the things we're working on at ENREL is how do you move away from food-based crops? So there's reasons why the market went that way to begin with. They're much easier to process. There was ways of getting alternative fuels into the marketplace quicker. But the downside is, you know, people and animals like to eat this stuff. And so you're going to need it going forward, so...

FLATOW: Well, we have 30 percent of the corn crop right, is it now, put into alcohol for fuel?

Dr. BRATIS: It's in that ballpark.

FLATOW: In that ballpark. Okay, so we want to get away from food-based crops.

Dr. BRATIS: Correct.

FLATOW: And we've heard about something called cellulosic ethanol over these years.

Dr. BRATIS: Right, and now...

FLATOW: How far are we we keep hearing oh, it's always three to five years away, you know, like a lot of these new technologies. Are we any closer?

Dr. BRATIS: That's right, and so first off, what cellulosic means is now you're dealing with things like the stalks of the corn plant. You're dealing with prairie grasses. You're dealing with woodchips and bark, you know, really, really rigid material that has the same sugars that are present in starch-based things like corn, but they're there in these really tough polymers that you have to break down.

And so this opens up supply a lot and gives you a heck of a lot more potential. The downside is, you know, if you try to take a piece of wood bark and a potato and throw it in a pot of boiling water, which one gets soft first? I mean, it's very difficult to convert these kind of things.

And that's the technology that we've been working on, and it's gone from (unintelligible) scale to pilot scale. And now what you see is you see demonstration plants that are being built throughout the country for cellulosic ethanol, and the technology has reached a point where we're ready to go at scale.

FLATOW: Now Lee Lynd, you're in the business of making cellulosic ethanol. Can you tell us about the ABCs of where it stands and where you can take it.

Dr. BRATIS: Sure. Well, I think one thing that's important to realize to start with is that you can get an awful lot of cellulosic biomass for $60 a dry ton or less. That happens to be $4 a gigajoule, perhaps arcane units, but that corresponds to $23 a barrel. So you've got a cost-competitive, and then some, raw material.

The reason that we don't have a cellulosic biofuel industry today is actually very simple. It's the difficulty of making reactive intermediates from this raw material.

Basically, nature has evolved biomass, cellulosic biomass, to be tough and resistant to microbial attack. And that really is where the focus is to remove the limiting factor. And that generally involves something called pretreatment, which is non-biological followed by microorganisms that I believe in the advanced configuration will directly ferment the cellulose. For now, people are also talking about producing cellulose enzymes separately that will dissolve this stuff.

FLATOW: So let me - just to boil it down for our audience, what you're saying is this heavy, woody stuff that makes up plants, it's hard to digest it open so that you can get inside. Is that correct? Would that be describing it the right way and then create the alcohol, then to ferment it.

Dr. BRATIS: Yeah, to ferment it, you need to dissolve it, and dissolving it's tough.

FLATOW: Yeah, and we haven't found a cheap, easy way to do that yet.

Dr. BRATIS: Not entirely. There are a lot of good ideas. People are working on it, but it's not a done deal.

FLATOW: We keep hearing, Lee Lynd, about new enzymes I was reading this week about a new enzyme that had come out that could drastically reduce the price and drastically increase the amount of energy we could get out per unit. Do we hear about do you hear about those all the time, also?

Dr. LYND: Yeah, there are new enzymes being discovered constantly. I don't particularly happen to think that they're generating radically different capability than old enzymes in general.

I'm more optimistic about the idea of getting microorganisms to produce the enzymes so that you don't have to pay a great deal of money to produce them in a separate, dedicated process step, but you know, to be fair, you could've gotten many people on this call, and they all have their favorite ideas. We'll see how it shakes out in the end.

FLATOW: Well, tell me about the microorganisms because I'm intrigued. You're saying if just get some bacteria or something like that to make the enzymes, we can do it a lot cheaper and better.

Dr. LYND: Yeah, much.

FLATOW: Do we have do we know what bacteria they are already and just a function of getting it to work?

Dr. LYND: There's two basic approaches. You can start off with microorganisms that grow really well in cellulose, and they're out there, but don't make any fuel very well, and you can try to modify those microorganisms to make fuel better.

The other thing you can do is start with organisms that make fuel really well but don't grow in cellulose, and you can modify them. Both of those have been done in principle, and in fact, going back to your point about how far away this is - my sense is that there are feed stocks that raw materials - for which no further process development is necessary in order to do this in a cost-effective way, so and that wasn't true a few years ago. So I think things really are progressing.

FLATOW: So what kind of feed stocks would they be, what kind of materials?

Dr. LYND: Yeah, there are some of them that are easier than others, and there are some that come along with more infrastructure preexisting than others. I happen to think that the easiest place to get cellulosic biofuel started is waste paper sludge that currently goes to the landfill and is a byproduct of paper making.

For reasons that would take probably too long to explain, I don't think that there's I think that's the lowest cost and fastest way to get this going. And if the right resources could be brought to bear, that plant could be operating in a year.

FLATOW: What do you mean the right resources? If somebody wanted to invest in it, I hear you saying - dollar signs.

Dr. LYND: That's right. They can give me a call.

(Soundbite of laughter)

Dr. LYND: But aside from that, yeah, I mean...

FLATOW: Well, you're saying that's all it is, someone who wants to take a chance on these waste paper materials.

Dr. LYND: Build, let's go.

FLATOW: Yeah, build the biofuels. It's ready to go. I just need some investor money because we think this is working, this is the low-hanging fruit. We can get the stuff on the road and show that it works.

Dr. LYND: Yeah, I think it's very logical to pursue a staircase, starting off with what's easy, and the history of this field has had a lot of people trying to value 100-foot cliffs with 10-foot poles, and so if instead of doing that we do things starting with the low-hanging fruit or the first steps on the staircase, I think we can go up that staircase pretty rapidly, and I think the world needs it.

FLATOW: Because the investors are looking for what we used to call the hula hoop, right? They want this big buck quickly on this kind of stuff, some big homerun that you're going to hit, and you're saying we need to take incremental steps on it.

Dr. LYND: Yeah, I think that's right.

FLATOW: Adam, what do you think?

Dr. BRATIS: Well, I think that's the right approach. I mean, the challenge with cellulosic ethanol compared to first-generation technologies, as Lee said, it's much more difficult to convert this material. So no matter what you do, the conversation cost is probably going to be more than it would be for a simple cornstarch-based process.

Now, the advantage is you can go after more advantageous and cheaper feed stocks, and the hope is to try to offset that. So I think what you need to do is you need to try to marry an enzyme and a fermentation process with an appropriate feed stock that happens to be an advantaged feed stock because remember, these plants are not going to be refinery-sized plants that produce 360,000 barrels of oil or ethanol a day.

These are going to be much smaller, based on corn-based ethanol, and they're going to be derived off the feed stock that's available within a certain radius of the plant that you put on. So you get your advantaged feed stock, and then you go from there, and you tailor your enzyme and your fermentation process to that advantaged feed stock, and I think you can get off the ground.

FLATOW: And Lee, how many gallons of ethanol could you make if we used the process that you're talking about now with that paper waste?

Dr. LYND: In the United States, you could make 500 million gallons a year, which isn't very much, actually. We use 140 billion gallons a year of gasoline, and so this is a place to get started. It's not the ultimate fruition, but again, you need to start up the staircase, and it's a great place to start.

FLATOW: And you say there are pilot programs around the country that are trying to do this, but they're not commercially viable yet.

Dr. LYND: Well, there are programs that are demonstrating technology at pilot scale. I suspect some of that will be commercially viable, but generally to commercialize it, you need to do it at pilot scale first.

FLATOW: All right, so if anyone want to get in on this and take a shot with Lee...

(Soundbite of laughter)

FLATOW: On how to get this cellulosic ethanol, they have your number. We'll see what we can get going on cellulosic ethanol. Thanks for taking time to be with us today.

Dr. LYND: You're very welcome.

FLATOW: We're going to take a break and come back more and talk to Adam Bratis, bring on other guests, 1-800-989-8255. Lee Lynd was the co-founder and chief officer at Mascoma Corporation based in Rome, New York. So we'll take a break. We'll be right back. Stay with us.

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FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY from NPR.

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FLATOW: You're listening to SCIENCE FRIDAY from NPR. I'm Ira Flatow. We're talking about alternative fuels. We're talking about alcohol for this part of the hour with my guest, Adam Bratis. He is the biofuels program manager at the National Renewable Energy Laboratory in Golden, Colorado.

Adam, is it feasible for alcohol to become our total fuel, replace gasoline in a great extent, or is it going to be always just a little piece of the mix and mixed in with gasoline?

Dr. BRATIS: I think you're going to see alcohol be a piece of the answer. So I think there are no I mean, despite what anybody comes on and tells you, I think we'll all agree that there are no absolute silver bullets in this field, and it's going to take a contribution from a multitude of feed stocks and a multitude of different fuel products at the end of the day.

Right now, nobody's blending ethanol and doesn't have the capability to blend ethanol into things like diesel or jet fuel. It's just gasoline. So while we're addressing the front of the process right now with cellulosic ethanol. That's what we talked about. Get away from food-based crops.

FLATOW: Right, right.

Dr. BRATIS: There is a need to address the back end, too. There will be some finite limit of how much ethanol you can blend in. Now feasibly, that could be as high as 85 percent in the E85 blends, right? I mean, you see those kinds of service stations around.

But there's also a move afoot to try to turn cellulosic material into whether it's being called advanced biofuels or hydrocarbon-like drop-in molecules that look a lot more like diesel or jet or gasoline going forward.

So ethanol can be a piece of the answer. I think other fuels will be a piece of the answer. You'll hear some people talk about some of those from algae later on, and I think you've got all kinds of other renewable energy technologies that will have to be a piece of the overall energy answer, as well.

FLATOW: How much money is going into cellulosic ethanol research compared to other kinds? I'm trying to get a feeling of, you know, this is a moderate amount, there's a lot, there's very little.

Dr. BRATIS: That's a difficult question to talk about. Nationally, I don't know everything that's going in, but if you look at where we are today in terms of investment into these types of alternative fuels and where we were 10 or 15 years ago, there is an order-of-magnitude difference in investment.

So there is a lot of effort going into this field for reasons of energy security, for reasons of, you know, greenhouse gas emissions that you've talked about.

FLATOW: And I guess it's finding the if he was correct, I think Lee had an interesting idea about find the right bacteria that could do this for us. It's possibly even genetically engineering that right kind of bacteria.

Dr. BRATIS: Right, people are working. People are working on these kinds of things. I mean, there's two general approaches. You have to make the cellulose accessible. So no matter what you do, you have to pre-treat this really, really rigid, hard material so that you can get enzymes in there, attack the cellulose, break them down into single simple sugars and then ferment those sugars like people have been doing for years in stills in their backyards or anywhere else, right?

So I mean, that's the general process. Now two approaches. One, you can independently attack that problem. You can have enzymes that go after it, and then you can have different fermentation organisms, and what Lee was talking about was you can also do it in a combinatorial fashion, where you have an organization that can secrete the enzymes you need but can also do the fermentation.

The advantage of that is obviously cost. The disadvantage is you can't optimize each one of those processes independently, and you have to look at that tradeoff and see what works best for your process.

FLATOW: All right, we've been talking about ethanol and how we can make it cheaply, what kind of plants are best to make it with and the kinds of microbes we might want to use. But ethanol is mostly a substitute for gasoline, and it's fuel for our cars.

What if you want to me, as you say, what if you want to make a different fuel that you can get from a regular barrel of oil like jet fuel or diesel fuel? Now, we get oil by tapping into those sources deep underground, under the water, and the remains of plants of organisms that lived millions of years ago that have been turned into crude oil.

But what if we didn't have to wait millions of years for that transformation to happen? What if we could speed up the process and harvest that oil from living organisms?

Dr. BRATIS: Well, I'd like to bring on two scientists who are doing just that. Richard Sayre is the director of the Enterprise Rent-A-Car Institute For Renewable Fuels at the Donald Danforth Plant Science Center in St. Louis, also director of the Center for Advanced Biofuel Systems there. He joins us from KWMU in St. Louis. Welcome back to SCIENCE FRIDAY.

Dr. RICHARD SAYRE (Director, Enterprise Rent-A-Car Institute For Renewable Fuels; Director, Center for Advanced Biofuel Systems, Donald Danforth Plant Science Center): Thank you very much.

FLATOW: You're welcome. Bruce Rittmann is the regents professor of environmental engineering at Arizona State University in Tempe. He's also the director of the Center for Environmental Biotechnology at the Biodesign Institute at ASU, and he joins us by phone. Welcome to the program, Dr. Rittmann.

Dr. BRUCE RITTMANN (Regents Professor, Environmental Engineering Director, Center for Environmental Biotechnology, Biodesign Institute, Arizona State University): Thank you, good afternoon, Ira.

FLATOW: Now Richard, when we were out there just a few weeks ago, you were giving me a tour of the facilities, and you were telling us, you were saying I can actually make algae that I can milk the oil out of.

Dr. SAYRE: Yes...

FLATOW: I'm not making that up, right?

(Soundbite of laughter)

Dr. SAYRE: No, you're not making it up, and we like to use the metaphor of a cattle feed lot, and so first we put the algae out into the pond, and that's equivalent to the pasture. Then we bring them into the feed lot, and we fatten them up a bit, and then we milk them.

And we have a process where we can nondestructively extract just the oil from the algae. The algae survive this process, and then they go back out into the pasture and get fat again.

The bottom line is you get about twice the productivity in oil production as you would if you destructively extracted the oil.

FLATOW: And how efficient can you make the oil?

Dr. SAYRE: Well, various studies have recently suggested, at least theoretically, that algae have between two- and 10-fold higher potential to produce biomass than any terrestrial crop system. And then added on top of that is the fact that when you harvest biomass from algae, you're actually harvesting 100 percent of the biomass. You're not leaving behind the cellulosics or the leaves, the stems and the roots. You're getting everything.

And so and on top of that, you can do it every day of the year, potentially. So it has a number of advantages over terrestrial biomass systems.

FLATOW: So how many, for example, give us an idea of how many gallons or barrels or whatever of oil you can get out of algae.

Dr. SAYRE: Yes, that's a great question, and the numbers range anywhere from a low of 1,000 gallons per acre per year to a theoretical achievable number of 6,000 gallons per acre per year, and that's without any genetic modification. Those are algae off the shelf, essentially.

If we improve the capture of light, the efficiency of photosynthesis, the efficiency of producing oils and perhaps, as you'll hear later, engineering algae actually to secrete oil, then we can increase those numbers even higher and potentially get up to 10,000 gallons per acre per year.

FLATOW: Ten thousand gallons per acre per year. Bruce Rittmann, you're trying to do something similar with a different kind of organism.

Dr. RITTMANN: Yes.

FLATOW: Tell us about that.

Dr. RITTMANN: Yes, well, we're using photosynthetic bacteria, also called cyanobacteria. These are like algae in the sense that they capture energy from the sun and take CO2, and then they make organic materials, usually themselves.

But we're going one step further with our cyanobacteria, and we're coaxing them to send that energy and that carbon that they fix not to making more of themselves but to producing and secreting the precursors to what is essentially petroleum substitute, materials that can be turned directly into jet fuel and diesel fuel.

And we use cyanobacteria for several reasons, but the most critical one here is we are able to modify these organisms so that they will divert their energy and their carbon flows to producing the product that we want, which are these materials that lead directly to producing the liquid transportation fuels.

FLATOW: And how much can you get out of these bacteria?

Dr. RITTMANN: Okay, well, the production rate should be similar to what you could get from just producing, you know, biomass similar to what Richard said. Let's put it on a very practical way and that is that we know the production rate that they can produce of this material, and if we were doing this and converting it into fuels, we could replace the world's entire use of fossil fuels with a land-surface area roughly the size of Texas.

FLATOW: The whole world?

Dr. RITTMANN: The entire world and all fossil fuel use, not just petroleum but all fossil fuel use. And this is the big advantage of using the photosynthetic microorganisms because their yield of high-value energy materials per acre of sunlight-capturing land is 10 to 100 or more times greater than possible with plants.

FLATOW: Richard, those are fighting words, I would think.

Dr. SAYRE: Yeah, yeah.

(Soundbite of laughter)

FLATOW: Especially in Texas.

(Soundbite of laughter)

Dr. SAYRE: Yeah, in Texas. This sounds like a set-up, actually. But that being said, there have actually been a number of papers that have recently been published in peer-reviewed journals that address the theoretical maximum of biomass production using solar radiation, and they take into account light scatter reflection, the efficiency of light capture and the conversion into carbohydrate, et cetera.

And the numbers that come out of that and this would include cyanobacteria because basically their photosynthesis is essentially identical to that of the - what we call eukaryotic algae. But the numbers are the numbers that I gave you earlier. And the theoretical maximum is the theoretical maximum, and that's based on the energy density coming from the sun. You can't produce more energy than you actually capture on the surface of the earth.

FLATOW: So how many states would it take to make - how many states -(unintelligible) Texas suffice(ph) if you used algae, or you need a few more states?

Dr. SAYRE: Well, yeah. I can give you a number for replacing the gasoline in the United States.

FLATOW: Right.

Dr. SAYRE: The estimate is, if we needed to choose a state, we would choose Virginia to replace the gasoline in the United States. And certainly, a gasoline consumption in the United States is only a small fraction of the world's fossil fuel consumption. So a state the size of Texas, frankly, I'd find it difficult to believe we could do that...

FLATOW: 1-800...

Dr. SAYRE: ...replace all the energy.

FLATOW: Well, I'm sorry. 1-800-989-8255 is our number.

How far, Adam, behind are algal fuel technologies from cellulosic technologies in terms of producing an affordable product, you know? For years, they were talking about making it from corn, right? Now they're not going to just switch and sink all that money in there.

Dr. BRATIS: Right. I think that's one of the fundamental challenges that people, you know, in general will agree upon is the cost of algal biofuels production. So there are, you know, I mean, there are demonstration plants out there for cellulosic ethanol today. And I see it as a gradual progression that we really need those demonstration plants to succeed. We need to start moving cellulosic ethanol into the marketplace. And then we need to start progressing demonstration plants in pilot facilities for some of these advanced biofuels types of molecules. And algae and cyanobacteria are a couple a way of getting there.

FLATOW: Mm-hmm.

Dr. BRATIS: And so while we might be, you know, producing ethanol at, you know, numbers that are in the ballpark of, you know, $2, 2.50, you know, somewhere in that range of dollars per gallon of ethanol today, you know, algae is still significantly higher than that.

FLATOW: Mm-hmm. And you would agree, Richard, that you're not in a ballpark yet with the (unintelligible).

Dr. SAYRE: No, we aren't. And a good point was made there. We don't have demonstration plants of the scale that are necessary to demonstrate the economics yet. But those are being constructed now, both on the private side, as well as the government-sponsored demonstration facilities.

FLATOW: Mm-hmm. You have your own little pond out there? Pond scum?

Dr. SAYRE: Well, we do.

(Soundbite of laughter)

Dr. SAYRE: I'm also part of a group called the National Alliance for Advanced Biofuels and Bioproducts. This is a DOE-sponsored program that, in three years, hopes to demonstrate the economic and feasibility of producing fuels from algae, as well as the energy efficiency and sustainability issues, address those.

FLATOW: Mm-hmm. Mm-hmm. 1-800-989-8255 is our number. Let's go to Jeff(ph) in Portland, Oregon. Hi, Jeff.

JEFF (Caller): Well, Ira, what a pleasure. Thank you so much.

FLATOW: You're welcome.

JEFF: Quick comment and three very important questions if you'll allow me. The human body requires digestive enzymes. You may know papain and bromelain that help us to metabolize food and be the lovely creatures that we are. But as to biofuels and algae and this new cyanobacteria as well, I have three questions. Number one, I understand that it can be done in the desert in ponds so we could take arid land, what was used to be called, ironically enough, wasteland on old maps, although I don't think any land is a wasteland in truth.

But - and also - the question is, how much water would it take to do ponds with algae? Can it be done at sea? And the third question, I think a very important one, what are the air pollution results from using jet fuels that may or may not, may ultimately be derived from cyanobacteria? Can the pollution at the highest levels of the stratosphere, which happens every day, can that actually be cut with your biofuels? And thanks very much.

FLATOW: You're welcome. We have a couple of minutes.

(Soundbite of laughter)

Dr. BRATIS: Okay.

FLATOW: How easy is it, you know, out there in the dry lands, he was saying?

Dr. BRATIS: Okay. Well, that's a very good point. And one of the values of using cyanobacteria or algae is that they don't grow in soil. They grow in liquid slurries. So you don't compete with arable lands we used to grow our food. So we're not competing in any way with that really important use of cropland. A very important goal here is to make these systems very water conservative so we don't use very much water.

Our systems are what we call closed photobioreactor systems. We just don't use open ponds and let water evaporate freely. And this allows us to have a very low water use and also essentially no water pollution, as you would have, if you had run off, say, from agricultural fields.

CONAN: All right. Let me remind everybody that I'm Ira Flatow and this is SCIENCE FRIDAY from NPR.

And he was also talking about worrying about what happens when that fuel gets burned in a...

Dr. BRATIS: Yes.

FLATOW: ...high flying jet.

Dr. BRATIS: Yeah. Okay, there are two aspects of that. And I want to focus on the global warming CO2 aspect. The key thing about using cyanobacteria or algae to produce these fuels is that it's completely renewable and carbon neutral. So we aren't adding any new carbon dioxide to the atmosphere. It's just carbon dioxide that came from the atmosphere, went into the cyanobacteria, the algae, and goes into fuels and goes back. It's cycling around. So we don't contribute in any way to, you know, buildup of CO2 and global climate change.

FLATOW: Mm-hmm.

Dr. SAYRE: If I can comment on that, actually.

FLATOW: Please.

Dr. SAYRE: I have to disagree with that comment. There are a number of life cycle analyses that demonstrate that algal biofuel - carbon footprint, when you compare it to petroleum, is about a 40 to 60 percent reduction in CO2 emissions.

The reason that's not 100 percent is that there's energy used in the manufacture of these products, in their transportation, in operating the ponds or the photobioreactors, et cetera. And currently, that energy is coming off the grid. So until we replace that energy we're using on the grid with renewable sources, you cannot get to 100 percent carbon recycling.

FLATOW: Mm-hmm. Just to comment from - tweet came in from TBalchamp(ph), who says, we're now making Virginia a unit of measurement. So we will now how many Virginias does it take, you know...

(Soundbite of laughter)

FLATOW: It's great. All right, we're going to take a break. And you can send us tweets, some more tweets at scifri@ - S-C-I-F-R-I. Also, you can go to our website. It's sciencefriday.com and give at least some comments on the discussions we're having here and talk amongst yourselves. And also, you can phone us, 1-800-989-8255, and talk on our Facebook page, if you like. So we'll take a break. We'll come back and talk lots more about alternative energies. We're talking with Richard Sayre and Bruce Rittmann.

Stay with us. We'll be right back.

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FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY from NPR.

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FLATOW: You're listening to SCIENCE FRIDAY. I'm Ira Flatow. We're talking this hour about biofuels, getting oil from algae and microbes, with my guests, Richard Sayre, Bruce Rittmann and Adam Bratis. Our number, 1-800-989-8255.

Let's talk a little bit, Adam, about the we talked about a little bit about the carbon footprint, the carbon emissions of these different alternatives. How does cellulosic ethanol, for example, stack up against corn ethanol, against gasoline...

Dr. BRATIS: Sure.

FLATOW: ...computing the carbon footprint?

Dr. BRATIS: The philosophy is exactly as Richard described it. I mean, it's essentially that what you have with either terrestrial biomass of marine-based or water-based biomass, like algae or cyanobacteria, is you have an effective carbon sink. So when you grow this stuff, it pulls CO2 out of the atmosphere, that's the plus. And then you go through conversion and you're going to have to use some energy sources. And if you use those energy sources from the plant instead of from, you know, the grid like we have today, then you can really help your carbon footprint. And then at the end of the day, you'll have to burn this stuff in an engine somewhere...

FLATOW: Mm-hmm.

Dr. BRATIS: ...and you're still going to get a CO2 emission's profile that's similar to the fuels you used today. So for cellulosic ethanol, if you use the plant and you use the portions of the plant that you're not converting to ethanol to burn, to get steam and power, which is what a lot of these demonstration facilities are trying to do, then overall relative to gasoline, you have about a 75 or 80 percent reduction in CO2 emissions.

FLATOW: Mm-hmm. And there are some people who were talking about a plant like a switchgrass that has a root system that stays in the ground and you take it off and you cut it and it regrows. But it stores - as it regrows, the roots grow bigger, so it's actually sucking in CO2 and storing it in the roots permanently.

Dr. BRATIS: Right. Right.

FLATOW: And so you get an added advantage of that's another way you make your footprint even smaller or you actually clean the air of CO2.

Dr. BRATIS: That's absolutely right.

FLATOW: Sounds like a...

Dr. BRATIS: That gets...

FLATOW: It sounds like a dream kind of plant, doesn't it?

Dr. BRATIS: It does. And not only that, it grows in pretty arid environments. So it...

FLATOW: And that's a tough one. Cellulosicy, that's a real tough one to crack, I would imagine, because it's so woody.

Dr. BRATIS: It's not that tough. We can...

FLATOW: Yeah?

Dr. BRATIS: I mean, things like corn stover and tree bark are actually a little bit more difficult to break down than switchgrass would be.

FLATOW: But we're not growing it anywhere, in any place.

Dr. BRATIS: But we're not growing it anywhere. That's the challenge. If you want to build a demonstration plant, where do you get it from today? And so...

FLATOW: Mm-hmm. 1-800-989-8255. Let's go to Ashley(ph) in Cleveland. Hi, Ashley.

ASHLEY (Caller): Hi, how are you?

FLATOW: Hey, how are you?

ASHLEY: Good. It's a pleasure to speak with you. I have a quick question about algae production. I saw something very interesting on the Internet. Actually, it was a couple of years ago. And it looked to be a very efficient and clean and controlled method of producing this algae biofuels and it was vertical storage inside. So...

FLATOW: Mm-hmm.

ASHLEY: ...they were taking algae and pushing it. There was a water-controlled method where it was stored. And it sounds like something that would shrink the size of your Virginia ponds to maybe, you know, Cleveland.

(Soundbite of laughter)

FLATOW: Yeah. Richard, you don't...

ASHLEY: (Unintelligible).

Dr. SAYRE: Yeah.

FLATOW: Richard, you don't grow yours indoors, right? What's the difference with what she's talking about and what you do?

Dr. SAYRE: Yes. Yes. It's that's a great example of some of the technologies that we're hearing about that are going on the market currently. But the bottom line is, you still have to deal with the amount of energy that falls on a square meter of the earth's surface. And how you intercept that energy is the issue that she's raising here. Can you do that vertically or can you do it horizontally? The bottom line, though, is it's still - it's a horizontal square footage that your system occupies that captures that energy. And so the vertical systems can work in maybe certain situations where you have steep topography, for example. But if you have flatland - the flatland system is as efficient as any vertical system.

FLATOW: Hmm.

ASHLEY: Okay, thank you.

FLATOW: All right. Have a good weekend.

ASHLEY: You too.

FLATOW: 1-800-989-8255. Let's go to the phones for another question. Rodney(ph) in Oswego, New York. Hi, Rodney.

RODNEY (Caller): Hi, how are you?

FLATOW: Hi there?

RODNEY: Yeah, my question was - well, I read an article in the Economist, oh, a couple months ago, I can't really remember - but in there, it shows what the carbon footprint. They were saying that the biofuels release nitrogen instead of carbon dioxide or CO2. And they were saying that nitrogen has the worst effect on the environment than the CO2 does. And I was just curious about that.

FLATOW: Mm-hmm. Okay, Adam, any reaction to that?

Dr. BRATIS: Well, I guess the fuels we're making aren't necessarily emitting any greater quantities of nitrogen or nitrous oxide than gasoline would or anything else would. So from an emission standpoint of when you burn the fuel, I would disagree with that statement. But I think what he's getting at is this whole effect of indirect land use. So where do you grow your biomass? I mean, the important thing about cellulosic ethanol we talked about so far is what you're growing, but there's also a very important issue of where you grow it. And so if you do things in an intelligent fashion and use land that's available to you that's not being used for other purposes much now, then you have a process that's going to work really well from a mission standpoint.

FLATOW: Mm-hmm.

Dr. RITTMANN: If you start tearing down trees that are already in place to plant other crops in place of them, that's not a very well - not a very smart usage of land. So depending on what kind of tilling practices you use and other things like that, you do have the potential to take things out of the picture that you don't want to take out of the picture. So...

FLATOW: Yeah.

Prof. RITTMANN: ...it's like any other process. You got to find an intelligent way to do it. And when you do, then you're going to have a positive impact.

FLATOW: Richard, a couple of questions for you, and I'll ask the same questions of Bruce. Is there a best place to grow the algae or to grow the cyanobacteria or can you spread it around the country? Do you need the desert, do you need that open land...

Dr. SAYRE: Yes.

FLATOW: ...to do that?

Dr. SAYRE: A very good question. And actually, we don't know the answer to that yet. There are number of areas that we think are probably optimal for growing algae. One of those that's clearly at the top of the list is Hawaii. Hawaii has a very constant temperature. It's an ideal temperature for growing algae, plenty of water available, and of course plenty of sunlight. The other area that gets a lot of attention is the Southwest. This was mentioned earlier. And the Southwest has about four times the annual solar influx than, say, the Northeast.

However, there's the issue of water availability in the Southwest and the fact that algae as well as plants all light saturate their photosynthesis at about one quarter of full sunlight intensity. So three quarters of the day, these organisms cannot use that extra light that's maybe available in an area that has high light intensities. That being said, the jury is still out and...

FLATOW: Why not grow them under those giant solar panels, right? We share the solar light...

Dr. SAYRE: Yeah. Well, one of the things we're doing...

FLATOW: ...quarter of the day, yeah.

Dr. SAYRE: Yeah. That's one approach. But again, you're losing that energy that the panel is intersecting, of course. But another approach is to increase the efficiency of that light capturing so that it wastes less energy. And it's really an issue of the energy that's wasted. It captures too much, more than it can use. And what we've been able to do in the laboratory is to reengineer the light capturing apparatus to make it more efficient so that it can use that high light intensity.

FLATOW: When you say the capturing apparatus, you're talking about the algae itself? Reengineering...

Dr. SAYRE: Yeah. So - exactly. So these are genetically modified algae. And what we've done is we've changed the size of the antenna. You can think of it as a dish antenna such as people use to capture their TV signals. We - we've gone from a very large dish to a smaller dish. And it turns out by using a smaller dish we can couple the rate of energy transfer more efficiently to the downstream biochemistry and lose less of the energy by wasteful emission processes.

FLATOW: Wow. That's interesting. And Bruce, do you have a better spot or an ideal spot to grow your bacteria?

Dr. RITTMANN: Well, I think I agree with most of what Richard said. And, you know, the key thing is you'd like to have days that have a lot of sun. The very cloudy areas would not be good. And Richard is right that you can have too much sun. But there are also ways to design and manage the photobioreactor systems to minimize the problems and take advantage of all of the sunlight for the organisms with it. And that's one of the key things we're doing in our research. So not only is it having good organisms that do the right job, but also creating the engineered system so that they work at their maximum efficiency.

FLATOW: Richard, why not grow them on water, you know, and on a sunny part of the ocean or something (unintelligible)...

Dr. SAYRE: Open ocean?

FLATOW: Yeah.

Dr. SAYRE: There are certainly a number of groups that are considering that. But the issue, I think, that most of us are concerned about is wave action and storms...

FLATOW: I see.

Dr. SAYRE: ...and how are you going to keep your apparatus from falling apart during a hurricane.

FLATOW: Oh, details, details.

Dr. SAYRE: Yeah.

(Soundbite of laughter)

FLATOW: Well, good luck to both of you. And thank you for taking time to be with us.

Dr. SAYRE: Thank you.

FLATOW: Richard Sayre is director of Enterprise Rent-A-Car Institute for Renewable Fuels at the Donald Danforth Plant Science Center in St. Louis, also director for the Center for Advanced Biofuel Systems there. Bruce Rittmann is a Regent's professor of environmental engineering at Arizona State University in Tempe and director of the Center for Environmental Biotechnology at the Biodesign Institute at ASU. And Adam Bratis is the biofuels program manager at the National Renewable Energy Laboratory in Golden, Colorado. Have a great weekend. Thank you, gentlemen.

Dr. RITTMANN: Thanks, Ira.

FLATOW: You know, we've looked at all kinds of ways to make fuel from living or once living things. We talked about grasses and cornstalks and green algae and bacteria. And there are many ways to get energy from living organisms. But how about getting it in the form of pure electricity? My next guest is here to talk about a new project dedicated to tapping electricity from bacteria. Living electricity living in the mud, directly tapping into them. Linda Chrisey is a microbial fuel cell program manager at the Office of Naval Research in Arlington. She joins us from Harvard today.

Welcome to SCIENCE FRIDAY, Dr. Chrisey.

Dr. LINDA CHRISEY (Office of Naval Research): Thank you for having me on your show, Ira.

FLATOW: Are you saying there are bacteria in the mud that just give off electricity?

Dr. CHRISEY: That's correct. And we've been looking at this technology for about 10 years now. And we think it'll help the Navy meet several of its critical needs. But yes, there are bacteria in the mud that naturally will take organic matter, so their fuel or(ph) small molecules - think of something like sugar, although that's not what you would find in a mud, they use this to fuel their internal metabolism. And when they complete that process, they have electrons left over. And what we've discovered is that they can transfer those electrons to an electrode if it's in the mud. And basically we can harvest pure electricity from this process.

FLATOW: You mean, if I go into the mud outside, I could - I could find this bacteria myself?

Dr. CHRISEY: You could. One of our scientists has actually helped several students do this as a science fair project. You could do it in a mud puddle. We found that in different environments - we've looked at the very deepest parts of the ocean, we've looked in shallow water, where we have sandy sediments and we've looked at harbors - and generally, we find we can get usable amounts of electricity in those sorts of environments.

FLATOW: Mm-hmm. We're talking about harvesting electricity from bacteria in mud this hour on SCIENCE FRIDAY from NPR. I'm Ira Flatow, talking with Dr. Linda Chrisey, who works for the Office of Naval Research in Arlington. So the mud is then like a giant bacteria - like a giant batteries for it?

Dr. CHRISEY: Exactly. That's a good way to think of it. The biggest difference, though, that I'd like to point out is where a battery has a finite number of reactants in it. It will exhaust itself after a period of time. We believe that this technology will offer a very long duration of power. In fact, it could potentially be infinite. I'm not just, you know, pulling that out of the air. We've had systems in the water that have operated for three years, continuously providing power to an oceanographic mooring. So...

FLATOW: So instead of a solar panel there, getting the light in the ocean, you're just sticking the probes in the mud.

Dr. CHRISEY: Exactly. And now, you know, these are modest amounts of power that are produced. If you want your audience to think a D cell battery has enough energy in it, a watt for about an hour...

FLATOW: Yeah.

Dr. CHRISEY: ...what we're looking at is a watt but continuously for nine months, 12 months or even longer. And that amount of power is sufficient to power some of the sensors and sensor networks the Navy is very interested in.

FLATOW: How much mud do you need? Or how much bacteria, I guess.

Dr. CHRISEY: Well, what we found - we can play around with the size of the anode; that's the electrode that actually gets in placed in the mud. And it's basically a function of how much energy you need. We can also think of pre-colonizing the anode before it goes in the mud with specific bacteria that we know are very capable and quite optimized to do this electron transfer process.

FLATOW: Do they have a name for this bacteria?

Dr. CHRISEY: So there are several. But the one that we've tended to focus on is called Geobacter.

FLATOW: Can I order this online...

(Soundbite of laughter)

FLATOW: ...and stick it outside and run my solar power or whatever from it?

Dr. CHRISEY: You could buy it. But it's probably in, you know, if you live near a beach somewhere...

FLATOW: Yeah.

Dr. CHRISEY: ...you could probably go down to the beach, dig down until the mud starts to smell a little stinky, and you probably have Geobacter there.

FLATOW: And the Navy is actually running it's sensing devices with this now?

Dr. CHRISEY: We're in the process of testing the utility of the microbial fuel cell to power different types of sensors that are of value to us. What we'd like to do is be able to persistently power sensors. So for example, instead of having to put a diver in the water to change the batteries on something...

FLATOW: Right.

Dr. CHRISEY: ...which could happen with some frequency, this would let us put a device in the water and allow it to sustainably operate for months or even years.

FLATOW: Mm-hmm. So you - you'd need pretty shallow water.

Dr. CHRISEY: No. We've tested these at a thousand meters.

FLATOW: No kidding.

Dr. CHRISEY: And they operate just fine.

FLATOW: Wow.

Dr. CHRISEY: It's pretty incredible.

FLATOW: So you can stick - you know, we talk about all these temperature sensors in the Gulf of Mexico, in hurricane season, whatever, you could put all these sensors around, they can stick in the mud...

Dr. CHRISEY: Yes.

FLATOW: ...and be continuously running?

Dr. CHRISEY: Yes. And I think a civilian application that might be very obvious to listeners is for monitoring earthquakes and seismic activity. Hydrophones, which are essentially underwater microphones...

FLATOW: Right.

Dr. CHRISEY: ...are placed on the seafloor. But they're actually very costly to maintain because somebody has to change the batteries or put new ones out there. This type of approach may allow us to really have very large grids of hydrophones to listen in the ocean for such events.

FLATOW: So it's - so the limiting factor is just how tough your sensor is, how long it's going to last, because you'll have the electricity there for it all the time.

Dr. CHRISEY: I would like to think that's the case. Yes.

FLATOW: And there is - it's limitless - I mean, just what your imagination can think you can make these out of.

Dr CHRISEY: Exactly. It could go on for years. And we're testing that now with certain sensors, for example, in San Diego Bay. We're trying to see if the microbial fuel cell could be useful in helping to monitor the green sea turtle population there.

FLATOW: Wow. So you detect the comings and goings.

Dr. CHRISEY: Right. The sea turtles have transmitters attached to them that emit a signal at a specific frequency. And then there are receivers for these signals around the bay and they require power. And right now they're using a couple of D cell batteries that have to be changed, you know, fairly regularly. But if we can get the microbial fuel cell to function and power these receivers, you may not have to send divers down every, you know, two weeks to change the batteries.

FLATOW: Can you tweak the bacteria and make - put out more voltage?

Dr. CHRISEY: Yes, we can. And I heard one of your prior speakers talk about genetic engineering. We're not doing that. Actually, we've figured out ways to adapt the bacteria to function at lower and lower voltages and have actually increased the amount of power they can produce eightfold...

FLATOW: Wow.

Dr. CHRISEY: ...which I think is pretty incredible.

FLATOW: So do I. And thank you for taking time to tell us. Fascinating stuff, Dr. Chrisey.

Dr. CHRISEY: Thank you.

FLATOW: Have a good weekend. Thanks for coming on.

Dr. CHRISEY: Thanks very much.

FLATOW: Linda Chrisey is the microbial fuel cell program manager at the Office of Naval Research in Arlington, Virginia. That's about all the time we have for today. So when you're out there mucking around in the mud looking for those bacteria, sticking those probes in there, think about us today, or talking about it over drinks tonight on Friday night.

Have a great weekend. We'll see you next week. I'm Ira Flatow in New York.

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