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Pond Scum or Planet Savers?

Posted by Dave Cohen on January 16, 2006 - 9:07pm
Topic: Alternative energy
Tags: algae farming, bioreactors, carbon emissions, greenfuel technologies, power plants [list all tags]

No, I am not referring to the IEA or CERA. As a change of pace away from the depressing geopolitical news concerning potential oil shocks, this story focuses on bioreactors and oil from algae farming. The title is taken from the story of the same name broadcast by Living On Earth (LOE) for the week of January 13th.
Pond scum just might be the answer to solving the CO2 woes of the industrial age. Host Bruce Gellerman visits with Dr. Isaac Berzin, founder of GreenFuel Technologies Corporation. Berzin is working on a prototype that uses algae to convert power plant emissions into biofuels.
Here's the audio for the interview (mp3). The primary issue for algae-based fuels is stated succinctly here [Biofutur, No. 255/May 2005 by Olivier Danielo].
In the context of climactic changes and of soaring prices for a barrel of petroleum, biofuels are now being presented as a renewable energy alternative. Presently, research is being done on microscopic algae which are particularly rich in oils and whose yield per hectare is considerably higher than that of sunflower or rapeseed. At the industrial level, bioreactors which use microalgae to trap CO2 and NOx [NO2, nitrogen oxide] are in active development in the United States....

Some species of algae are so rich in oil that it accounts for over 50% of their mass. NREL [National Renewable Energy Laboratory] has selected approximately 300 species of algae, as varied as the diatoms (genera Amphora, Cymbella, Nitzschia, etc.) and green algae (genera Chlorella in particular)....

Diatoms, or Bacillariophytes, are unicellular, microscopic algae.... These organisms are widespread in salt water, where they constitute the largest portion of phytoplankton biomass, but they are also found in freshwater. There exist approximately 100,000 known species around the world. More than 400 new specimens are described each year. Certain species are particularly rich in oils.
It's worth noting that NREL, which has been active in algae farming research, has had its funding cut in the most recent federal budget round. However, Greenfuel Technologies anticipates a profitable privatized business for bioreactors. Let's take a look at the true promise of algae farming in the context of high oil prices and climate change.
Conceptually, algae farming is simple as framed by Isaac Berzin of Greenfuels. Here's the bioreactor at MIT.


Bioreactors will be co-located with power plants that emit CO2 (carbon dioxide). The CO2 must be sequestered at the plant and fed as an input to the algae farm. From Berzin:
Actually, in professional terms it's called a bioreactor. It's nothing but three tubes connected together with some sea water and algae in them. And you can see the bubbles bubbling through the system. And you can kind of look at the bubble and follow it, and in the ten seconds or so that the bubbles are spending in the bioreactor 80 percent of the CO2 is moved and 85 percent of the NOX [NO2]. And at the end of the day you harvest the algae, whatever was growing during the day, you take out of the system. It's like a cow you milk it and you make biofuels from the algae.
Sounds pretty good, doesn't it? In fact, the interviewer Bruce Gellerman thought it sounded too good to be true.
GELLERMAN: So, I was taught, you know, if it sounds too good to be true it usually is. What am I missing?

BERZIN: I'll tell you what the problem is. You have to produce algae in a cost that will be cheap enough to compete with fossil fuels. Then you think, wait a minute, what does this technology need? It needs land, and you need water, and you need CO2. So, CO2 is not an issue. You're located next to a CO2 generating facility. Water, you get to use any quality of water. Treated sewage water, brackish water, ocean water, any water available. The third thing is, the land, usually near these big power plants, no one wants to live. It's non-fertile land, nothing grows there even. So, you don't really compete with agriculture. So, how realistic this is? We believe it is realistic.
So, the process requires CO2, water and some unused land. Not competing with agriculture is one of the stronger points supporting bioreactors, as Olivier Danielo notes
The production of traditional biofuels requires expansive land surfaces for cultivation. Terrestrial biofuels come traditionally from two sources: oil, produced from sunflower or rapeseed, and alcohol, produced from the fermentation of sugars from beets, wheat, or corn.

The production of these biofuels necessitates the use of large tracts of land. According to Jean Marc Jancovici, an engineer specializing in greenhouse gas emissions, it would require a sunflower field 118% the size of France to replace the 50Mtep of petroleum consumed each year by the French for their transportation needs (104% of the size of France for rapeseed, 120% for beet, 2700% for wheat).
Oil from algae requires less land but as Gellerman notes, "theoretically, if you created an algae bioreactor twice the size of New Jersey, you could supply the entire petroleum needs of the U.S". So, there's still a small land problem in replacing our fossil fuels with biofuels from algae farms. And of course, bioreactors are not a panacea that frees us from CO2 emissions. Yes, most of the CO2 (and NO2, another greenhouse gas) is captured at the power plant and consumed by the algae. The resulting biofuels can be "used to run engines, or converted into methane or fermented into alcohol". But there is still a problem of course because CO2 will be released into the atmosphere via downstream tailpipe emissions.

This subject first came up at TOD months ago in a few comments I can't find. A recommended resource advocating producing biodiesel from algae is the UNH Biodiesel Group (University of New Hampshire). This topic also came up in some comments by ericy and joule in response to a previous post Weyburn, CO2 Injection and Carbon Sequestration. You can find out more about what NREL is up to here.

On the whole, using pond scum to decrease CO2 emissions (at least at power plants) seems like a good idea. Harvesting eukaryotic algae doesn't put us in much spiritual jeopardy, right? If the technology was intensely used internationally, we wouldn't have as much to worry about when it comes to this guy.


Smokestack emissions bubble
through algae-filled tubes at
MIT's Cogen plant (from LOE)

This high-tech farming doesn't solve all our woes but it's certainly better than nothing.

56 comments on Pond Scum or Planet Savers?

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Reed on January 16, 2006 - 9:23pm Permalink | Subthread | Comments top
What me worry? He's old and over the hill and I'm sure all of you can come up with a solution for us.
(Excerpt)
"The world has already passed the point of no return for climate change, and civilisation as we know it is now unlikely to survive, according to James Lovelock, the scientist and green guru who conceived the idea of Gaia - the Earth which keeps itself fit for life.

In a profoundly pessimistic new assessment, published in today's Independent, Professor Lovelock suggests that efforts to counter global warming cannot succeed, and that, in effect, it is already too late."

http://energybulletin.net/12126.html

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LevinK on January 17, 2006 - 1:06am Permalink | Subthread | Parent | Comments top
Yeah and the ecoterrorists opposing nuclear power carry at least half of the responsibility for that. One would think that the mean of a bunch of greedy capitalists and a bunch of idealists would be a double bunch of far-looking realists but it does not turn out so.
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Stuart Staniford on January 17, 2006 - 1:13am Permalink | Subthread | Parent | Comments top
From a short article by Prof. Lovelock:
Our planet has kept itself healthy and fit for life, just like an animal does, for most of the more than three billion years of its existence. It was ill luck that we started polluting at a time when the sun is too hot for comfort. We have given Gaia a fever and soon her condition will worsen to a state like a coma. She has been there before and recovered, but it took more than 100,000 years. We are responsible and will suffer the consequences: as the century progresses, the temperature will rise 8 degrees centigrade in temperate regions and 5 degrees in the tropics.

Much of the tropical land mass will become scrub and desert, and will no longer serve for regulation; this adds to the 40 percent of the Earth's surface we have depleted to feed ourselves.

I'm willing to believe that climate change can happen very fast, and I'm willing to believe there's at least some chance we've past a point of no return where it runs away and there's really nothing we can do. But Professor Lovelock's scenario is a little extreme for me. I don't get where he comes up with the tropical scrub and desert. Maybe I'll have to wait for his book. But it seems to me the worst case has to be bounded by somthing like the Paleocene-Eocene Thermal Maximum. The Eocene Climate was certainly incredibly different today. The adjustment would be absolutely brutal. But it wasn't scrub and desert:

At the beginning of the Eocene, the high temperatures and warm oceans created a moist, balmy environment, with forests spreading throughout the earth from pole to pole. Apart from the driest deserts, Earth must have been entirely covered in forests.

Polar forests were quite extensive. Fossils and even preserved remains of trees such as swamp cypress and dawn redwood from the Eocene have been found in Ellesmere Island in the Canadian Arctic. As aforementioned, the preseved remains found in the Canadian Arctic are not fossils, but actual pieces preserved in oxygen-poor water in the swampy forests of the time, and then buried before they had the chance to decompose. Even at that time, Ellesmere Island was only a few degrees in latitude further south than it is today. Fossils of subtropical and even tropical trees and plants from the Eocene have also been found in Greenland and Alaska. Tropical rainforests grew as far north as the Pacific Northwest and Europe.

Palm trees were growing as far north as Alaska and northern Europe during the early Eocene, although they became less and less abundant as the climate cooled. Dawn redwoods were far more extensive as well.

and
The oldest known fossils of most of the modern mammal orders appear within a brief period during the early Eocene. At the beginning of the Eocene, several new mammal groups arrived in North America. These modern mammals, like artiodactyls, perissodactyls and primates, had features like long, thin legs, feet and hands capable of grasping, as well as differentiated teeth adapted for chewing. Dwarf forms reigned. All the members of the new mammal orders were small, under 10 kg; based on comparisons of tooth size, Eocene mammals were only 60 per cent of the size of the primitive Paleocene mammals that had preceded them. They were also smaller than the mammals that followed them. It is assumed that the hot Eocene temperatures favored smaller animals that were better able to manage heat.

Both groups of modern ungulates (hoofed animals) became prevalent due to a major radiation between Europe and North America; along with carnivourous ungulates like Mesonyx. Early forms of many other modern mammalian orders appeared, including bats, proboscidians, primates, rodents and marsupials. Older primitive forms of mammals declined in variety and importance. Important Eocene land fauna fossil remains have been found in western North America, Europe, Patagonia, Egypt and South-East Asia. Marine fauna are best known from South Asia and the southeast United States.

Reptile fossils are also known from the Eocene, such as the fearsomely enormous crocodile Deinosuchus, which lived as far north as Wyoming during the Eocene and grew much larger than the modern-day saltwater crocodile. Python fossils and turtle fossils are also known from North America. During the Eocene plants and marine faunas became quite modern. Many modern bird orders first appear in the Eocene.

I realize this is small comfort, and climate change worries the hell out of me, but I just can't get quite as far into the blackness as Prof. Lovelock.
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LevinK on January 17, 2006 - 1:35am Permalink | Subthread | Parent | Comments top
There were no humans back there in the Eocene to cut down the trees to free farmland. In the absence of huge forests absorbing the excess rain and heat, the sun together with the wind and water erosion will start converting the farmland into desert in a matter of decades. AFAIK this is what happened after ancient Rome a Carthage cut down the trees in Northern Africa to build their ships.
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Southsider1 on January 17, 2006 - 2:41am Permalink | Subthread | Parent | Comments top
First the Romans got to enjoy six centuries or so of intensive grain farming, much as is currently the case in those regions of the U.S. midwest where the aboriginal forests were felled in the 19th century. Of course, with modern farming practices, the notion that the midwest will continue to provide bountiful harvests for many hundreds of years to come is questionable.
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PaulusP on January 17, 2006 - 10:59am Permalink | Subthread | Parent | Comments top
Much less comforting still, is the fact that we have no idea at all from which era exactly origins the present global warming. Is it from 10 years back? 35? Maybe 50? No one really knows. If present global warming is the backlash of our fossilfuel burning of, say, the 70's, what will our present fossil fuel use mean for global warming in 2030? I think it will be a greatly accelerating process, way beyond what we can establish by reducing emissions to 1990 levels by 2010, as per Kyoto. Besides, the biggest polluters on earth are exempt or did not sign this treaty, and the ones that did will not be able to meet the goals. Not a rosy outlook for my country where 10 million people live below sealevel. I suppose I should be moving to higher ground before the rest starts outselling their homes.
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Nate Hagens on January 16, 2006 - 9:42pm Permalink | Subthread | Comments top
In addition to land, water and CO2, we would need some sort of holding tank. Presumably, in labs these are made from concrete and such, which I dont know the EROI specifics on but I believe that is where the limiting factor lies rather than water or land.

I guess we could cordon off one of the Great Lakes for full-time algae production....but then where would the walleye and jet skiers go...?

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DIYer on January 16, 2006 - 10:14pm Permalink | Subthread | Comments top
This project, and biodiesel, and cellulosic ethanol, and photovoltaics, and windfarms are all better than nothing.

However the sheer scale of the problem is mind boggling. For every kilogram of carbon we burn, we produce 3.67 kilograms of CO2. And we have some electric plants that currently burn a trainload of coal every day. That's a lotta flue gas to try to round up and feed to the algae. Looks like a nice pilot project, but if he's gonna capture -all- the CO2, he'll need a bioreactor the size of Missouri or so (an exaggeration, but still...)

The bottom line is, we're going to conserve whether we like it or not. Eventually nuclear may partially replace some of the demand, but our greed for energy is about to find its limit.

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odograph on January 16, 2006 - 10:19pm Permalink | Subthread | Comments top
I'll have to follow those links and listen to those mp3s when I have more time.  The algae systems are interesting, but I'm cautious about the maintenance required by these tube-based system.  My intuition as an ex-chemist, aquarist, and goldfish pond owner is that they will be high maintenance.  And certainly, they can't touch a pond for photon capture.  No matter how you stack your tubes, you're still going to have light hitting racks, mounts, struts ...

On the other hand, they look really zippy, and no doubt serve to attract funding much better than a boring pond.

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odograph on January 16, 2006 - 10:26pm Permalink | Subthread | Parent | Comments top
BTW, the advantage of tubes in an experimental setup is that you can monitor inputs and outputs more carefully.  There is no pond surface to atmosphere transfer to be guessed at.  So, a loss in efficiency is balanced(?) by an increase in monitoring.

I suppose covered ponds would give you an ability to measure surface transfer, but you have to maintain your pond cover.

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ericy on January 16, 2006 - 11:16pm Permalink | Subthread | Parent | Comments top

The people who first started looking at algae were considering open ponds - I imagine because of the low capital costs.  These days people have given up on that approach, for several reasons.

First of all, some strains of algae have a high oil content, but many do not.  In an open pond, what would happen is that you get competing strains growing in the pond which you don't want.  A closed system makes it much easier to keep out unwanted strains of algae.

Secondly, it is harder to maintain the optimum growth temperature in an open pond.

Finally, I gather that an open pond would lose a lot of water from evaporation.  A closed system wouldn't have this problem.

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odograph on January 17, 2006 - 10:17am Permalink | Subthread | Parent | Comments top
I hadn't heard that you need to limit growth to certain species.  Certainly a pond evloves over time ...

That would absolutely be enough to require a closed system.

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TJ on January 17, 2006 - 10:22am Permalink | Subthread | Parent | Comments top
I'd guess that this will never happen unless they figure out how to make a pond work.  Miles of plastic tubing would be a maintenance nightmare; any blockages would have to be cleared by hand.

A bioreactor might work for a furnace output, if you could find people willing to pay for the installation.

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Magnus Redin on January 17, 2006 - 11:28am Permalink | Subthread | Parent | Comments top
Pump cleaning plugs thru the pipes at regular intervalls. I would be more worried about finding a long lived transparent plastic that is not turned brittle or opaque from UV radiation.  Long lived tubing is important for good economy.
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TJ on January 17, 2006 - 1:49pm Permalink | Subthread | Parent | Comments top
Won't work.  Phytofermentans did the math.  You're talking thousands of 20' plastic tubes all manifolded together in parallel.  To prevent blockages you would have to regularly backflush each tube.  The piping and valving alone for the gas, water, and cleaning would cost several times what the tubing would.
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liferaft on January 16, 2006 - 10:27pm Permalink | Subthread | Comments top
What a deal - turn NJ and say, Massachussetts - into an algae farm!  Seriously, a simple bioreactor design that gave a fuel yield might be a big step towards a more natural feed forward/feed back process, e.g. where process outputs are all used as inputs to other stages and there is little "waste".  This is a fundamental of permaculture design for sustainability.
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DuncanK on January 16, 2006 - 10:42pm Permalink | Subthread | Comments top
Now if we can just collect that methane given off by the plants, then we'd have our NG too!

Actually, with a stretch of the imagination, you can see that you could make that Carbon go a long way.

You could take the methane given off from your compost heap and composting toilet and use it to heat your home, then take the C02 from the burning gas and pass it through your little algae farm so that you can harvest the oil to put in your car! Of course you could feed the car's exhaust fumes through the algae tubes mounted on the roof of the car to make more oil!

Hey! We're saved!

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baka on January 16, 2006 - 11:39pm Permalink | Subthread | Parent | Comments top
I'm not sure where the best place to post this is... but here seems ok.

For those that have not had a look at the Keppler et al paper on "Methane emmissions from terrestrial plants under aerobic conditions" (Nature 439 p187)...

The authors suggest that reduction in this natural source due to deforestation may account for the recent slowing in the rate of increase of methane.

Figure 1 shows that the levels we are talking about (for Ash and Beech) are ~0 - 1 ng/g(dry weight)per hour at 20-30 C increasing to 1-2 ng/g/hr in an exponential manner as temperature goes to 50 - 60 C.  Summed over entire forests this quicly becomes large.

It also indicates that as the average temperature increases the rate of release increases (+ve feedback)  until the plant dies (the release of methane from leaf litter is,according to the authors,  many orders of magnitude lower than live leaf tissue) ... at which point it no longer absorbs CO2.

This is a more important point than the one picked up by the media that plants emit methane.

Expect follow ups and revisions on this issue.

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dissident on January 17, 2006 - 11:45am Permalink | Subthread | Parent | Comments top
Coverage of this story has been rather ignorant.  The methane emissions from forests were part of the normal climate equilibrium on this planet.  The world is experiencing deforestation at the hands of humans, yet greenhouse warming is accelerating.  Since most living trees increase their mass with time they must be a net sink for carbon, so the methane emissions cannot be greater than the carbon dioxide consumption.  Methane is a more effective greenhouse gas but it gets broken down by photolysis in the upper stratosphere
leading to an atmospheric residence time of about 10 years instead of centuries like for CO2.  This whole subject has little bearing on global warming but is being cast as if it is evidence that global warming is caused by trees.
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ericy on January 16, 2006 - 11:11pm Permalink | Subthread | Comments top
A couple of points.

My view is that if this can be made to work, it is hard to come up with any downside to any of this.  Make no mistake - it is a transitional technology that we can use while we are burning something to make electricity.

There is a 2nd company out there working on a flue gas to algae type of system.  More information here:

http://www.greencarcongress.com/2005/12/greenshift_lice.html

The main difference between these two seems to be the design of the photobioreactor.

One of the authors of the UNH report blogs over at www.biodieselnow.com.  They have an alternative plan that they are looking at that is based upon growing algae using agricultural waste/runoff or wastewater treatment plants, and then make fuel from that.  One other point - people who search the web about biodiesel made from algae oftentimes find a paper written by the group at UNH that talks about using open ponds in the Sonoran desert.  The author of the paper was really only using this as an example in order to illustrate the point that algal biodiesel could in theory scale to replace all petroleum, and wasn't intended as a serious suggestion that we literally build these things in the desert.

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Boof on January 16, 2006 - 11:16pm Permalink | Subthread | Comments top
We need to know the EROEI of a fully integrated plant. At the minimum there will be extra power demands for pumping the flue gas, for collecting the algae and then drying it into a refinable feedstock. Also the capital cost of the reactors. The system is not carbon neutral as the coal keeps adding new carbon. Therefore we should ask if it has better overall efficiency than a CTL or ICG plant that merely vents its flue gas to the atmosphere.

While multicellular fuels such as tree trunks are slow growing they are self-feeding and easily harvested.

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ericy on January 16, 2006 - 11:31pm Permalink | Subthread | Parent | Comments top
Given that you are adjacent to a power plant, there ought to be adequate waste heat that can be used  for drying (should drying be needed).  Actually I don't think drying would be needed - vegetable oil will float on water.  I once asked the Mike Briggs at UNH how you separate the oil - I don't remember what he said, but my recollection is that it wasn't really a big deal.

Asking about the EROEI is certainly valid, but I don't know the answer.

The problem with trees is that they don't grow quickly enough.  Just look at the weight of biomass per sq km for a forest and you end up needing huge amounts of land.  Essentially the same problem you have with using oilseeds as the basis for biodiesel.

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Nate Hagens on January 16, 2006 - 11:47pm Permalink | Subthread | Parent | Comments top
to separate the oil I believe you just squeeze it, like you would a hemp or sesame seed. Small scale presses are easy but not sure how its done on large scale.
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phytofermentans on January 16, 2006 - 11:59pm Permalink | Subthread | Comments top

The amount of tubing is definitely the issue. 20cm gives you the best light capture (unless you modify the photo antenna of the algae), so how much 20cm tubing do you need to soak up a 100 megawatt coal power station?

Quite a bit actually. 5% photosynthetic efficiency would be impressive for an algae bioreactor.  The heat of combustion of coal is 23.0 MJ/kg, with ~50% efficiency (impressive), so a 100Mw station uses ~8kg of coal a second. The heat of combustion of glucose is 2830kj/mol, which gives an idea for the amount of sunlight required to convert CO2 to algae (assuming perfectly efficient photosynthesis). 8kg of carbon is about 660 moles of carbon which would make 110 moles of glucose requiring about 300 Mj of sunlight, in this best and brightest of all possible worlds. That corresponds to 300Mwatts of solar collection *20 for the efficiency of photo capture of super algae, and thats 8 Gwatts of collector area, which on a sunny day is about 8 million sq. metres of surface area. So you would need 40,000 km of tubing. If you made it in plastic thats at least $100M of tube and would circle the earth, or if you plumbed it carefully, it would cover an 8km^2 area (not so bad really).

So really you want to make a lake and aseptically isolate it from the ravenous external environment. Which is going to be expensive. Otherwise with such a large operation how do you avoid weed algae and microscopic predators getting into the massive amount of bioreactor? The predators will grow exponentially and your genetically modified super-oil-producing algae becomes breakfast. I suspect this is why the DOE funding dried up. Scaling from a 10L bioreactor to a 8km^2 lake is quite a problem.

The best way out of this dilemma is to use an algae which has few predators, something like an extremophile, such as Dunellia salina which grows in brine. This way you can grow it in open ponds (already done commercially), and 50% of its mass is glycerol which will burn in a modified diesel engine. The byproduct is protein and vitamins. But now I am sounding like a Cornucopian, so let shooting season begin, please shoot me down in flame!

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Nate Hagens on January 17, 2006 - 12:02am Permalink | Subthread | Parent | Comments top
with a moniker like "phytofermentans", who would dare shoot you down in an algae thread...? :)
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TJ on January 17, 2006 - 10:06am Permalink | Subthread | Parent | Comments top
Using a pond is the only feasible way to handle that much CO2.  You couldn't afford the investment for 42,000 km of tubing, or the power required to push the gas thru 42,000 km of tubing.  

Don't forget the power required to sequester the CO2 and store it overnight while the sun is down.

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odograph on January 17, 2006 - 10:48am Permalink | Subthread | Parent | Comments top
Well, the Salton Sea is just sitting there.

(I think this has been recommended before)

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phytofermentans on January 17, 2006 - 12:12am Permalink | Subthread | Comments top
I was looking forward to being flamed too.. :-(
Just call me Ishmael then..

Seriously though, the algae could be dried using waste heat, crushed to extract the glycerol and burnt in a diesel engine with a heated injector system. Or even better, a gas turbine. Glycerol burns quite well, though the exhaust would need some cleaning.

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LJR on January 17, 2006 - 1:59am Permalink | Subthread | Comments top
Hey!  If this works out The Oil Drum can become The Scum Drum.
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LJR on January 17, 2006 - 12:07pm Permalink | Subthread | Parent | Comments top
Our motto:  Algae news that's fit to print!
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rototillerman on January 17, 2006 - 1:59am Permalink | Subthread | Comments top
Somehow I'm suspicious of this whole process.  My reasoning goes like this: CO2 is the end result of burning, which released energy.  As such, CO2 is a low-energy chemical compound.  The algae have the job of taking this low-energy compound, and 'pumping it up' into a higher energy compound (the oil).  Where does it get its energy to do this?  Well, the major input that I see here is the solar radiation (though perhaps the residual heat in the flue gases play some small part).  As such, the solar radiation would seem to form an upper bound on the amount of energy coming out of the system.  If one assumes the process is 100% efficient (hah), what size irradiated area is needed to produce X amount of biofuel energy?

Also, does the conversion scale up and down in productivity on an hourly basis in relation to the instantaneous solar flux?  Do the algae 'turn off' at night?

On a related item, has anyone found any verification of George Monbiot's claims that humankind uses 400 times the carbon budget of the earth annually? See http://www.energybulletin.net/11525.html

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LevinK on January 17, 2006 - 3:54am Permalink | Subthread | Parent | Comments top
They are not Monbiot's, he is just quoting Jeffrey Dukes. The discussion  on peakoil.com is very interesting, they are debating the article and a lot about is for the validity of this particular claim. Overall it turns to be factually correct but is a bit misleading in the context of biofuels, because the efficiency of biofuel production is times more than the efficiency of the formation of fossil fuels. A less misleading quote would be that to replace our current fossil fuel consumption we are going to convert the biomass of 22% of all land plants to BF, this including forests etc (Dukes again). But the point is taken - both facts show that BF may not be (and must not be!) considered that silver bullet that will save us, or even fill some significant portion of the gap; Reading the article shows pretty clearly why it MUST NOT be allowed to scale without some kind of control.
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Boof on January 17, 2006 - 8:32am Permalink | Subthread | Parent | Comments top
The killer advantage of biofuels are that they are a complementary commodity to piston engines, which are cheap ($35/kw) and can be fixed in backyards. The trick is to amplify that advantage with other energy types, such as plug-in hybrids, co-production and localisation.
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NC on January 17, 2006 - 10:34am Permalink | Subthread | Parent | Comments top
I am only aware of one commercial algae application.  The oil output is specificically very high quality, non-GMO, omega-3 fatty acids.  Algal oil has a high content of EPA and DHA which are long chain omega-3 unsaturated oils.  These oils are required for cognitive development in animals.  Most poultry, beef and pork are devoid of EPA & DHA.  Only cold water fishes and flax have high omega-3 oil fractions.  

The people that are in this area can get a high dollar price for their oil, think $100,s per pound.  They need this price because the cost of production is extremely high.  Doing this process as an energy source (instead of food source) is not going to happen anytime soon.

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joule on January 17, 2006 - 11:44am Permalink | Subthread | Comments top
I fully share the skepticism of rototillerman and phytofermentans. (Gotta love those names!)

First off, I am amused by this image of stack gas gently 'bubbling' up through those nice plastic tubes. However, let us not lose sight of the fact that even a moderate size coal-fired power plant has a stack gas flow rate of several hundred thousand cubic feet per minute.  In normal practice the pressure drop from the exit of the boilers through the stack plus whatever air pollution control device is used is only several inches of water.  However, if you were to take that same stack gas and try to push it up through what looks to be water-filled tubes roughly 20 -25 feet high, you will need massive blowers just to get all that stack gas through the water, and the pumping energy will increase by several orders of magnitude. So that in and of itself is one major energy drain.

And yes, we are talking about literally many miles of plastic tubing just for one medium size power plant. While you can grow algae in shallow covered ponds, were you to do so, then how would you uniformly contact the stack gas with all that shallow water? Bioreactors are fine .... until they get too big. Just because growing algae in a bioreactor is more space-efficient than growing convential land crops doesn't necessarily mean that it's either more cost-effective or more energy efficient.

Nor can one ignore the difficulty, expense, and energy expended in processing the algae. First, it has to be separated from the aqueous medium by any number of dewatering steps, all of which consume energy. Then if drying is involved, that's another large energy drain (though waste heat might possibly be used). Then there is the extraction of the oil and further processing. These are not trivial processing challenges and represent considerable energy drains.  

I think rototillerman hit the nail right on the head: what we have here is really a low-efficiency solar collector that instead of making either electricity or hot water makes biomass from which an oil-like substance can be extracted. It does this by taking CO2 and, using solar energy, converts it back into a reduced form of carbon, which can then be burned again and release the orginal CO2 back into the atmosphere.  The same amount of CO2 is eventually released into the atmosphere as if you just burned the coal. What has changed is that you are getting more BTUs out of the original carbon and hydrogen in the coal by installing what is essentially a solar energy 'boost' into the process. It is not at all clear what the  EROEI of this process really is.

I realize that the objective is to make a liquid fuel, but it seems to me like a lot of trouble in relation to what is gained. I tend to think that you might be better off just installing a conventional solar collector and making electricity directly from it. Hell, if you want a fuel, you can use the solar energy to make hydrogen.
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LevinK on January 17, 2006 - 11:56am Permalink | Subthread | Parent | Comments top
I think the algae utilises some of the waste heat from the smokestack gases, which should be improving the EROEI. I even suspect that this is its primary energy source, not sunlight.

Otherwise I agree.

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joule on January 17, 2006 - 1:12pm Permalink | Subthread | Parent | Comments top
I'm afraid I have to disagree about the heat in the stack gas being the primary source of energy for the algae. If that were the case, then why would it even be necessary to have it exposed to sunlight at all?

While a higher operating temperature will cause the biochemical reactions to proceed at a faster rate, it will not appreciably contribute to the oxidation/reduction reactions that produce cellular mass from the CO2 carbon source and nutrients.

Like tree or a blade of grass, the algae is acting as a solar collector that uses the energy to produce reduced carbon from CO2.

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baka on January 17, 2006 - 11:51pm Permalink | Subthread | Parent | Comments top
Picking up on a few points here...

joule is correct in pointing out the limitations of a pipe based system particularily in regards to blowing the flue gases through a ~10 column of water... a problem that is further compounded by the fact that at night you will have to mix the flue gases with air to provide the algae with sufficient oxygen... as the balance of oxygen production (during CO2 fixation) to oxygen consumption during respiration in the dark will reverse... unless you intend to use some of the power of the generator for lights!? I think this is not a problem in the pond scenario as I'm guessing that the overall biomass density is lower... and the surface to air ratio larger.

This reminds me of the same 10-20% power drag that  seq