# Algae to the rescue

by Ivan Seeking
Tags: algae, rescue
 PF Gold P: 2,215 Thank you for keeping on these developments Ivan!
P: 149
According to the calculations by Dr. David JC MacKay in his book "Sustainable Energy – without the hot air", it looks like CO2 enriched algae is about 20 times better than corn based ethanol per square meter. The numbers were:

Bioethanol from corn: 0.2W/m2
Bioethanol from sugar cane: 1.2W/m2
CO2 Enriched Algae Biodiesal: 4W/m2

The calculations are on pages 284-285

You can download the whole book here:
Or go straight to the html page here:
http://www.inference.phy.cam.ac.uk/w...page_284.shtml

The printed version actually says 0.02 for corn but there is a errata entry in the html version that says:

 Page 284 Bioethanol section: "0.02 W/m**2" should be "0.2 W/m**2". To make this section more informative I would rewrite it thus: 1 acre produces 122 bushels of corn per year, which makes 122 x 2.6 US gallons of ethanol, which at 84000 BTU per gallon would mean a power per unit area of {0.2 W/m^2}; however, the energy inputs required to process the corn into ethanol amount to 83,000 BTU per gallon; so 99% of the energy produced is used up by the processing, and the net power per unit area is about {0.002 W/m^2}. The only way to get significant net power from the corn-to-ethanol process is to ensure that all co-products are exploited; including the energy in the co-products, the net power per unit area is about 0.05 W/m^2.
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 Quote by joelupchurch 1 acre produces 122 bushels of corn per year, which makes 122 x 2.6 US gallons of ethanol, which at 84000 BTU per gallon would mean a power per unit area of {0.2 W/m^2}; however, the energy inputs required to process the corn into ethanol amount to 83,000 BTU per gallon; so 99% of the energy produced is used up by the processing, and the net power per unit area is about {0.002 W/m^2}. The only way to get significant net power from the corn-to-ethanol process is to ensure that all co-products are exploited; including the energy in the co-products, the net power per unit area is about 0.05 W/m^2.
The net-net yield of the corn-ethanol process is hotly debated. Many people argue that the efficiency of the complete process is zero or worse - meaning [as you know] that we derive no benefit whatsoever, or we are even losing energy! Most standard sources seem to place the processing efficiency at about 30%. But one has to be careful about which number is being cited. I tend to refer to the "net yield" as the yield after including energy for processing. Then there is what I tend to refer to as the net-net yield, which includes the fuel for tractors and land management, hidden energy costs in the fertilizers, soil supplements, pesticides, antifungals, or whatever else might be used, the energy for pumping water, etc.
 P: 149 When I applied MacKay's numbers of 60 grams of CO2 per square meter and multiplied by the 10,000 tons of CO2 per day produced by a 500MW coal plant and came up with 17SqKm of Algae. That comes out to a Algae field 4km on the side, which doesn't sound too bad, if you assume a sunny climate with cheap real estate. Of course, sunny and cheap usually means a desert, so the water consumption situation needs to be analyzed. Anybody want to calculate how much biodiesel 17 SqKm of algae would produce? I find this interesting, since if the law starts requiring CCS for coal and natural gas plants, then the biodiesel would offset part of the capture cost and avoid the sequestration part entirely. There was a recent Harvard study, "Realistic Costs of Carbon Capture", that estimated $35 to$70 per ton of CO2 capture. http://belfercenter.ksg.harvard.edu/publication/19185/realistic_costs_of_carbon_capture.html Since the Algae only need 10% CO2, it isn't clear what you need to do to the output of the coal plant before you feed it to the algae if you have stack scrubbers. I should point out that the biodiesel produced isn't technically renewable, since it is produced using the carbon from the coal and not from the atmosphere. I don't think CCS is practical, or that the continued use of coal is desirable, but I always like to check the math.
P: 149
 Quote by Ivan Seeking The net-net yield of the corn-ethanol process is hotly debated. Many people argue that the efficiency of the complete process is zero or worse - meaning [as you know] that we derive no benefit whatsoever, or we are even losing energy! Most standard sources seem to place the processing efficiency at about 30%. But one has to be careful about which number is being cited. I tend to refer to the "net yield" as the yield after including energy for processing. Then there is what I tend to refer to as the net-net yield, which includes the fuel for tractors and land management, hidden energy costs in the fertilizers, soil supplements, pesticides, antifungals, or whatever else might be used, the energy for pumping water, etc.
It seems to me MacKay's numbers are pretty close to 30%. He assume a gross of .2 w/m2 and a net of .05w/m2 which is a 25% net yield.

I would like to point out that from a climate perspective corn based ethanol makes little sense, even if the economics are better than break even. It can only offset the CO2 going into the corn, not the CO2 produced by the infrastructure to raise the corn. It seems to me that we would come out ahead on CO2 if we switched more of our vehicle fleet to compressed natural gas, since it produces much less CO2 per KWH.
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 Quote by joelupchurch When I applied MacKay's numbers of 60 grams of CO2 per square meter and multiplied by the 10,000 tons of CO2 per day produced by a 500MW coal plant and came up with 17SqKm of Algae. That comes out to a Algae field 4km on the side, which doesn't sound too bad, if you assume a sunny climate with cheap real estate. Of course, sunny and cheap usually means a desert, so the water consumption situation needs to be analyzed. Anybody want to calculate how much biodiesel 17 SqKm of algae would produce?
See up thread per Ivan: conservatively 2000 GPAY . 17 sq km = 4200 acres, or 8.5 million gallons per year.

 I find this interesting, since if the law starts requiring CCS for coal and natural gas plants, then the biodiesel would offset part of the capture cost and avoid the sequestration part entirely.
As you noted, many of those coal plants are located where there isn't good sun.
 P: 149 Maybe you could use some concentrators to get more sunlight for the algae. Down here in Florida we have plenty of sun. Will algae work in saltwater? How about partially processed sewage? Here is a new announcement from a company called Origin Oil about a method to "milk" the oil out of the algae without harvesting it. http://www.originoil.com/company-new...xtraction.html
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 Quote by joelupchurch Maybe you could use some concentrators to get more sunlight for the algae.
My impression is that this can be done in areas that are low on light. But more significant is the length of the day, and temperature. Keeping the algae cool in full light is one of the challenges for bioreactor designs. In the Aquatic Species Program, the winter temperatures are what killed the blooms [one example of why open systems can't work, imo]. There was plenty of light, but it was simply too cold.

As for the length of day, obviously the energy input to the system is reduced by having shorter days. IIRC from reading the literature current a couple of years ago, algae can be productive for up to about sixteen hours a day if light is available. Of course this led many of the fringe developers to provide artificial lighting, which is obviously a losing proposition!

 Down here in Florida we have plenty of sun. Will algae work in saltwater?
Yes. There are many varieties of salt-water algae, and there are some known to be good producers of oil.

 How about partially processed sewage?
Yes. Algae has the potential to treat many types of waste including industrial, municipal, and agricultural waste products. In the case of agriculture, the controlled growth of algae could be used to remediate runoff that creates dead zones in the ocean. The runoff is typically high in nitrogen, which algae love. In fact it is the uncontrolled growth of algae that depletes the oxygen needed for aquatic life. We could control this, solve the problem, and produce fuel as a consequence.
P: 1,409
Looks like the algae phase may be entirely unnecessary.
http://www.cbsnews.com/stories/2009/...n5190810.shtml
 The Cambridge, Mass.-based company on Monday is disclosing its technology and business plans for making ethanol and other liquid fuels from genetically-manipulated microorganisms that have been fed only sunlight and carbon dioxide.
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 Quote by Skyhunter Looks like the algae phase may be entirely unnecessary. http://www.cbsnews.com/stories/2009/...n5190810.shtml
Sounds great! We will have to see if the reality meets the hype. [a news release is a far cry from years of real testing, as we have with algae]

One issue that bothers me is that they make ethanol. When one considers the offset in energy and efficiency as compared to diesel, 25,000 gallons of ethanol is probably worth about 10,000 gallons of biodiesel. This means added distribution costs. There is also the problem of being incompatible with heavy trucks and aircraft. Recall that an algae-jatropha oil mix was recently tested in a 737. It passed with flying colors.
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 Quote by Skyhunter Looks like the algae phase may be entirely unnecessary. http://www.cbsnews.com/stories/2009/...n5190810.shtml
 The Cambridge, Mass.-based company on Monday is disclosing its technology and business plans for making ethanol and other liquid fuels from genetically-manipulated microorganisms that have been fed only sunlight and carbon dioxide.
Well fundamentally they've haven't changed anything in that statment, just the DNA. Algae is essentially "microorganisms that have been fed only sunlight and carbon dioxide". The issues of temperature, invasion by other strains in open systems, and in general the issues separation of the hydrocarbon product, large water requirments and a dedicated CO2 sources still remain. The only stand out part of the article to my mind is
 The company estimates it can produce 20,000 gallons of fuel per acre per year, which is far more than existing processes or others under development.
As that is indeed far better (10 to 2X better) than processes with natural strains, if they can do it.
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 Quote by Ivan Seeking ... One issue that bothers me is that they make ethanol. ...
Maybe not:
 Quote by Cnet Tech News ...It claims that it can make its end product - ethanol or another hydrocarbon fuel - ...
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 Quote by mheslep Maybe not:
To me, that is key. Ethanol makes no sense on so many levels that to me it hardly seems worth consideration in any case [including cellulosic ethanol], but if they can make biodiesel, that would be another matter. At the least, we will need biodiesel in addition to other options.

Key also is that the claim of quantities is based on ethanol. In order to judge fairly, we need to know the rates and costs of production for biodiesel feedstock.

I think most serious people who have looked at algae expect bioengineering to play a key role. While it may be possible to convert now using natural strains, the question is, at what cost? Whereas natural algae fuels and cellulosic ethanol are sometimes referred to as second generation fuels - corn-ethanol and soy-biodiesel are first generation fuels - this and other similar work may be examples of third generation fuel technologies.

The best news of all is that this is beginning to look like a horse race! I think we have seen at least a half dozen approaches to advanced fuel technolgies.
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This just popped up:
Given that the US Marines burn through 800,000 gallons of fuel a day in Afghanistan (alone), they are well motivated to find ways of reducing the logistics tale. Turns out one of the things they (the DoD) have been working on is algae, made in the battlefield no less:
http://www.independent.co.uk/news/bu...e-1766017.html
 Quote by The Independent Can Darpa now score another double success by changing how both the military and civilian worlds consume and produce energy? ... With the expense of convoys and guards thrown in, the cost of a gallon of fuel used at the front can range from $15 to several hundred dollars, says the same report. ... It now wants to develop inexpensive diesel and jet fuel from algae that could be produced in the battle zone. All three programmes include the aim of accelerating the manufacture of any new product by private companies, from whom the military could buy. ... Others say Darpa's goals can be unrealistic. Darpa wants to reduce the current cost of algae-based fuel from$20-$30 per gallon down to$3. In January, Darpa awarded contracts worth up to $34.8m to two companies to produce aviation fuel at$3 a gallon from algae. The competitors are General Atomics, best known for its Predator drone, and Science Applications International. They have three years to do it. Some doubt these companies – or any company – can achieve that goal.
Anyone care to comment on The Independent's '$20-$30' per gallon figure? It seems inappropriate to call it the 'current' figure, and not the theoretical figure given no large scale production (yet).

I also see, however, that at least half of the fuel goes to running field generators at forward bases. Now that is a perfect case for one of these small portable nuclear designs running around, say a 15ton 25 MW design that could be flown in by C130, and not biofuel.
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 Quote by mheslep Anyone care to comment on The Independent's '$20-$30' per gallon figure?
The Aquatic Species Program estimated a cost of about $2 per gallon. If we factor in inflation,$3 is probably reasonable, and DARPA landed precisely where I did on price expectations. In the end I used a retail price of 3\$ as a basis and tried to drive the production costs accordingly.