Algal Fuels and Massive Scales

Guest post by John Goetz

I keep an active watch of the news for progress being made in the areas of renewable and alternative energy sources. One area that has caught my eye is algal fuel (biofuel produced by algae). One company that has been in the news lately is Sapphire Energy, which claims to be able to produce ASTM compliant 91-octane biogasoline. Sapphire Energy says their technology “requires only sunlight, CO2 and non-potable water – and can be produced at massive scale on non-arable land”.

I am not trying to pick on any one solution or Sapphire Energy in particular. I simply wondered how massive a scale of CO2 and non-arable land is needed to make a noticeable dent in our gasoline demand.

First, how much CO2 do we need? The IPCC guidelines for calculating emissions require that an oxidation factor of 0.99 be applied to gasoline’s carbon content to account for a small portion of the fuel that is not oxidized into CO2. To calculate the CO2 emissions from a gallon of fuel, the carbon emissions are multiplied by the ratio of the molecular weight of CO2 to the molecular weight of carbon, or 44/12. Thus, the IPCC says the CO2 emissions from a gallon of gasoline = 2,421 grams x 0.99 x (44/12) = 8,788 grams = 8.8 kg/gallon = 19.4 pounds/gallon.

Now let’s assume Sapphire Energy simply reverses the process and consumes the CO2 to produce gasoline. In other words, we take 19.4 pounds of CO2 out of the atmosphere for every gallon of gasoline we produce. This seems like is a nice “carbon neutral” process.

What is the cubic volume of atmosphere required to make 1 gallon of gas? Let’s assume for the moment an efficiency factor of 100%, meaning our process will consume 100% of the atmospheric CO2 it is fed. This is unrealistic, but it is unrealistic on the “optimistic” side. According to the EPA, one cubic meter of CO2 gas weighs 0.2294 lbs. At an atmospheric concentration level of 385ppm, one cubic meter of atmosphere contains 0.000088319 lbs of CO2. Thus, 19.4 / .000088319 = 219658 cubic meters (yes, I am ignoring the atmospheric density gradient as one moves from the ground upward, but hang with me). This equates to roughly 4553 gallons of gasoline per cubic kilometer of air.

According to the US Energy Information Administration, US gasoline consumption is currently averaging (4-week rolling) 9.027 million barrels of gasoline per day, or about 379 million gallons (42 gallons per barrel). Thus, to completely replace US gasoline consumption, Sapphire Energy would need to “scrub”, at 100% efficiency, just over 83000 cubic kilometers of air per day. Certainly there is plenty of air available – this volume represents less than 0.02% of the volume of air in the first 1 km of atmosphere. Nevertheless, it is an enormous amount to process each day.

Of course, Sapphire Energy’s near-term goals are much more modest. As CEO Jason Pyle told Biomass Magazine, “the company is currently deploying a three-year pilot process with the goal of opening a 153 MMgy (10,000 barrel per day) production facility by 2011 at a site yet to be determined.” Using my fuzzy math above, that equates to a minimum of 92 cubic kilometers of air a day. Still seems like a lot.

So where will all of the CO2 come from?

Presumably the answer is coal-fired power plants. But let’s see if that makes sense. According to Science Daily, the top twelve CO2-emitting power plants in the US have total emissions of 236.8 million tons annually, or 1.3 billion pounds per day. Now, if that can be converted completely to gasoline, it would amount to 67 million gallons per day, or roughly 1/6 of the daily gasoline consumption.

(Science Daily refers to the twelve as the “dirty dozen,” which I found somewhat humorous given that CO2 is colorless and odorless, and is presumably needed to sustain some forms of life. But then again, so is dirt.)

Sounds great, except that a lot of land is needed to grow all that algae. According to Wikipedia, between 5,000 and 20,000 gallons of biodiesel can be produced per acre from algae per year. Assume for the moment that biogasoline can be produced at the same rate per acre. If we attempted to produce 67 million gallons of gasoline from our “dirty-dozen” every day, we would need between 1.2M and 4.9M acres of land to do this on. The low-end of the scale puts the area needed at more than that of Rhode Island. The high-end adds in Connecticut.

I kind of doubt there is that much land around each of the dirty dozen facilities. This means the gas would have to be sent by pipeline to a giant algae field. Given our ability to pipe oil and natural gas all over the place, sending CO2 across the country via pipeline is probably doable. There may also be plenty of unused or abandoned land (think abandoned oil fields) available to produce the gasoline. Nevertheless, the production scale and transportation logistics required to make this a viable alternative do indeed look massive.

So while the technology holds promise at the micro-scale, it remains to be seen what can actually be done at a scale that matters.

Talk among yourselves.


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I don’t know… Think of all the habitat you’d be destroying for these massive algae farms… We wouldn’t want to impact the desert tortoise or other native species. Perhaps after we force the country off of cow meat we can use the land for this noble purpose.


Sounds like a plan and since it is carbon neutral maybe God will cut us some slack to get the system operational since we are repenting of our grievous sin of carbon emission.

There’s a whole bunch of foreclosed houses that have pools FULL of algae. We could use those. Hey, I’ve been trying to convince people that the bad economy has a silver lining!!!

retired engineer

I suppose they could make extra CO2 by burning trees. That would be carbon neutral, sort of. What do they do with the CO2 at night or on cloudy days?

Bruce Cobb

Hmmm…. Cost of production per gallon of the stuff currently running as much as $20. Suddenly very sleepy. Wake me when it hits $2 a gallon.

Bill Marsh

19.4 pounds of CO2/gal? I don’t think a gallon of gas weighs 19.4 lbs so how could it produce 19.4 pounds of C02 — unless it assumes the oxygen used in the CO2 is not contained in the gasoline?
Reply: Yes, the assumption is that the oxygen molecule comes from the air.


I use about a gallon of gasoline a day. If this technology would allow me to produce gas at that rate in my backyard, I’d be set. Selling or licensing technology to individuals to meet their own needs would be like the ‘solar panel’ business model, with people producing their own energy, and avoiding the need for massive, large scale production facilities.
Reply: I read somewhere, and now cannot find it, that a 2000 sq ft rooftop system could produce about 10 gallons (I believe of biodiesel) per week. The system might cost $18000 though.

doug w

But what about the emissions from buring the bio-gasoline? While possibly neutral, Isn’t that still an emission?
The loons who are flogging CO2=evil want nothing less than the destruction of the engine that runs our economy. They are willing to sacrifice all of humanity to achieve their ends. They will support alternative fuels only as long as it diverts attention from their goal.


guilty as charged
“We are guilty.
We have sinned.
So we know from James Hansen”
Oh, that’s sad.
What did you do?
“It was diurnal
and nocturnal
emissions of CO2.”

Leon Brozyna

It may be doable but the question that remains is if it is economically feasible. There would also be the inevitable environmental impact studies in locating such facilities on non-arable land. This is what venture capital managers would need to know before sinking funds in such a massive undertaking. On the cost side are such details as the material costs of structures, costs of water, costs of recycling water for reuse, costs of obtaining CO2 to increase productivity. Then such costs would have to be measured against projected yields. Would the resulting gasoline be economically competitive, ideally being cheaper than present wholesale gasoline prices. If they can prove competitiveness, responsible venture capitalists should have no problem in plugging in the start-up costs. However, if the costs are seen as prohibitive the venture should be allowed to mature further rather than see a rush to federal subsidies and another ethanol-style debacle.
The cynic in me doubts that this’ll see much progress as it’ll probably face furious resistance from environmentalists appalled at the prospect of easily obtained gasoline.

Robert Wood

Thanks for doing the basic numbers for me; I normally have to do them for myself :^)
It appears that all microbial approaches have similar limits as alcohol. It is only possible to produce a good, strong hooch with distillation, concentration after the production. The same with hydrocarbons; it took millenia of forest and grass decay, over a large area, to produce the highly concentrated oil fields.
The problem with all “natural” or “sustainable” energy sources is that they are disbursed and therefore uneconomical.
I think that these biological processes could be improved upon by using a continuous flow, rather than batch, production method.

Tom Klein

I can visualize these huge algae ponds – I saw an estimate of 95 million acres required – and environmentalist living near or downwind from these ponds. Will they look back to off-shore drilling rigs with nostalgia, or just sue regardless that it was their desire that created them in the first place.

Steven Hill

I can hear it now…..too little CO2 causes man made ice age.

Bill Illis

Gasoline and fossil fuels are just hydrocarbons (with a very small amount of other molecules thrown in which are primarily contaminants). All one needs to produce gasoline is Carbon and Hydrogen and the right chemical reactions to produce C8H18.
Lots of different processes will potentially produce C8H18 (gasoline) some of which are biological and others which are artificial.
Given that Carbon and Hydrogen are extremely abundant elements, I imagine some day, someone will perfect an economical method of producing gasoline and other fossil fuels through a simple chemistry/refining process.
We don’t need plant remains to be buried deep in the Earth for millions of years to produce oil and coal and gasoline. We just need a feedstock of Carbon and Hydrogen.
The biggest problem is the other abundant element Oxygen – given that Oxygen likes to bond very strongly with both of our desired elements. We need to keep Oxygen out of the process until it is needed to produce the energy that we want fossil fuels to produce – ie heat through burning and combustion which produces CO2 and H2O.
It can easily be a completely renewable process.

Ken Westerman

Man if only electric cars/hydrogen fuel cell technology was cheaper to afford and the infrastructure was in place. I would totally buy either depending on <> in the future.
Algae though? Wonder if it could be collected from large blooms in the oceans? May be that’d be better than draining swamps and pools?
It’s good to see people’s ideas swirling about these topics though. I’m sure whomever creates something worthwhile in the automotive/energy business…will be the next billionaire for sure!

Steve Moore

“…maybe God will cut us some slack…”
He’ll have to check with Al first.


The production of algal biodiesel does not require distillation, just hot pressing. I think you can get about 60% of the weight in fuel. the left overs which are carbohydrates and proteins can then be used for ethanol production or stock feed. I’m not sure if these guys are doing something different. The main challenge ahead is finding appropriate high yielding strains. It can be performed on roof tops, in deserts or oceans. you can use salt water or effluent! when you consider other biofuels would require more area than the whole of the USA to meet your fuel requirements then the area required is tiny! Obviously the US need to move to more efficient cars. The rest of the world is happy with less than 2L (I have a 1.3L)! Compressed air cars are probably the way to go, no batteries to replace after a few years!
As for CO2 sources you should be not be short of supplies, anything that flames of ferments will provide it. People could run their heater exhaust through their rooftop biodiesel generator.
CO2 may not be responsible for climate change but it doesn’t mean we should be wasteful with fossil fuels.

Jeff Alberts

Sounds like a plan and since it is carbon neutral maybe God will cut us some slack to get the system operational since we are repenting of our grievous sin of carbon emission.

Why stop with god. Why not Thor, or Zeus?


best plan would be educate the mass to stop consume certain things. It’s not like we have only little choices. make it into laws.


Anyone want to volunteer to be sitting near the high pressure compressed air tank when the car is rear-ended?

Reply: I read somewhere, and now cannot find it, that a 2000 sq ft rooftop system could produce about 10 gallons (I believe of biodiesel) per week. The system might cost $18000 though.
10 gal X $4.00/gal = $40/week = $2,000/year; about an 11% return in a world of 3% CD rates.
Sign me up!!


“Why stop with god. Why not Thor, or Zeus?” Jeff Alberts
I kinda liked Thor. He was the only Marvel hero who could go toe-toe with the Hulk. He said once “Never have I been struck such a blow by a mere mortal!” I sure wish I had kept that issue, probably worth quite a lot.


We need one of these where you add pond scum instead of sugar.


Why stop with god. Why not Thor, or Zeus?
I think we want Hephaestus in on this one. Maybe with an assist from Demeter and/or Dionysus.


A critical limiting factor is the available sunlight. The algal ponds have to be in lower latitudes because winter sun angles are too steep in the north. Sunlight in the photosynthetic wavelengths doesn’t penetrate too far into water that’s dense with algal cells either, so the surface area of the ponds will have to be maximized.
There’s been some success with small-scale operations on farms using algae (Spirulina spp.) to clean nutrients out of animal waste, but for making fuel this seems to have the numbers running against it in so many ways.


How about a bug that eats trash and excretes petrol? Would that hold more promise than algal fuel?

Bill Illis (17:40:31) wrote:
“Given that Carbon and Hydrogen are extremely abundant elements, I imagine some day, someone will perfect an economical method of producing gasoline and other fossil fuels through a simple chemistry/refining process.”
You’re forgetting the whole point of the process – making gasoline or other hydrocarbons takes a lot of energy. While coal has a lot of carbon as carbon, there is very little hydrogen that isn’t bound to something else, usually oxygen.
That’s the whole point of photosynthesis – it uses sunlight to split water, discarding the oxygen and combining the hydrogen with CO2 to make glucose. Research is ongoing into not biologic equivalents to photosynthesis, but the result will still need sunlight as the energy source, it won’t be “simple chemistry” in a test tube.

Stan Needham

Reply: I read somewhere, and now cannot find it, that a 2000 sq ft rooftop system could produce about 10 gallons (I believe of biodiesel) per week. The system might cost $18000 though.
Come on, Anthony; what’s a couple bucks compared to saving the planet. Besides, as Smokey notes, the ROI beats current CD rates.


So….. The 19 pounds of CO2 is calculated by taking Oxygen from the atmosphere…. Fair enough….. All sounds complicated.
The only thing I give a stuff about, is the price. Make a fuel that burns in my conventional car, cheaper than what anybody else produces…. and which doesn’t send the price of food through the roof….. I’ll buy it. Otherwise it’s just a waste of time.
CO2 has no significant effect on climate…. So all I’m interested in is cheaper fuel…. How about liquefying our coal and shale deposits…. much more scope there ‘eh?…. America, India, Australia and South Africa. Just those four democratic nations control over 50% of the worlds coal deposits… and that’s not counting shale oil deposits…. Time we thought about it.


fusion power + Water = Hydrogen
Hydrogen + CO2 = gasoline
gasoline + car = go
go + environmental wacko = environmental wacko go mad


Just a note on yer pond scum petrol….. The land area needed could be reduced dramatically if you used vertical density…. Put the little green buggers in hi rise columns of water….. But that sounds like an engineering nightmare…. Liquefying coal and shale sounds much easier…. cheaper… : )

Geoff Dawson

These projects have been around before in other high cost fuel era’s.
However if they can crack it good for them. Also you don’t have to scrub the
air for the CO2, power stations do it for you, any carbon fueled combustion
process will produce predominately nitrogen( a fertilizer) and C02.
Both algal and bacteria love the stuff.
Connect them to the back end of coal fired power stations with plenty of land
to compensate for the solar efficiency dramas then you don’t need carbon
geological dumping programs.

Jon Jewett

An Integrated Gasification Combined Cycle coal fired electrical generating plant produces an effluent of nearly 100% CO2 (if they use pure O2 in the process). The idea is that it is easier to sequester pure CO2 than if the effluent is diluted with some 70% N2. The only down side is that the process consumes a significant fraction of the power produced (on the order of 1/3 to 1/2).
An IGCC plant costs more to build (perhaps 50% more) and more to operate (a very complicated process, especially with the O2 liquefaction train, and LOX (liquid O2) really is nasty stuff). And since it consumes so much power internally, it will require on the order of 30% to 50% more fuel per MWhr.
There are plants that actually do this. But, it seems to me that the only way they make economic sense is if either: 1. It is the only way to produce power by law. 2. The byproducts are worth something.
You could use the CO2 effluent for a feed stock to make Algal Gasoline. (I vote we call it “Alligator Gas”)
There is one operating plant that I have heard of making money. It was built by the government during the Carter energy debacle and closed down as uneconomical. A company bought the closed plant, spent a zillion dollars on modifying it, and now operate the plant and sell the CO2 for oil field enhanced production.
By the way: the government is going to build another one in Illinois. But Senator Harry Reid has said that he will never allow a commercial plant to be built. So, when the whole idea fizzles out, some enterprising young fellow can make a bundle-again.
I would enjoy this a whole lot more if I had studied abnormal psychology instead of marine engineering.
Steamboat Jack


Why is it [really?] important to be “carbon neutral” when in elementary school everyone was taught that CO2 was a necessary gaseous exchange in the human inhalation-exhalation cycle? Is there such a thing as being “carbon neutral” when some enterprising individuals created a “bank” where you can buy (give me a break!) carbon credits? Why am I skeptical or am I using critical thinking skills? Hmmm… Personally, I like the thought of the proposed wave energy technology for creating electricity (some posts are on my blog). That sounds like sound science to me.


Put them on old retrofit oil tankers.

Paul Linsay

MIT bioreactor in operation

Andrew Upson

Way OT but I can’t find your email address on this site. Any commentary to be forthcomeing on this?,2933,372542,00.html


Somewhere, I saw some film about a biomass rig that had the algae in vertical transparent tubes to reduce the acreage/ output ratio. However, given that the CO2 curve and the global temp. curves show zero correlation, we really need to give up on all this alternative fuels bushwa and burn gasoline in good health.


J. Hansford,
another company DOES use vertical racks of bladders!!
Of course, this guy sounds pretty good too!!


This guy is working on the VERTICAL algae “ponds”:
This guy has genetically modified bacteria for more efficiency!!

David Segesta

I’m a firm believer in capitalism. If someone can produce gasoline or diesel oil at a competitive price this way then they will. And they’ll be richly rewarded for their efforts.

David Segesta

Here is a video on a similar process.
As usual I remain a skeptic. If it really works why don’t they just stop talking and start producing the stuff and getting rich?


Liquefying coal and shale sounds much easier…. cheaper… : )
I thought they were working on a superheated steam method to just boil the stuff out. There is a staggering amount of shale oil in the US. Some Ellis Wyatt type (or team) is bound to go get it.


The problem with most biofuels is the land area required, and thus the direct affect on the environment through land clearing and the like. I would much prefer to use forests from 50 million years ago for my fuel, through the use of fossil fuels, till the professor brings me back a Mr. Fusion.


this calculation can be compared with the area required for a solarthermal power plant:
here we have 134 mill kWh from 400 acres in 1year = 335000 kWh/acre in 1year.
This is 335000 kJ/s*3600s = 1.21E6 MJ per acre in 1 year.
5000-20000 gallons / acre in 1 year
a gallon is 3.78 liters, and 1 litre of biodiesel has 34 MJ/liter
so we have an energy between
5000*3.78*34MJ = 0.64E6 MJ per acre and year
20000*3.78*34MJ = 2.57E6 MJ per acre and year
So the numbers are quite similar, though the solarthermal plant produces electricity what would be interesting with the use of highly efficient electric cars in the future, while algae produce biofuel, what is required now.
finally, it woud be interesting to compare the costs of solarthermal power generation with the CHEAPEST type of bioenergie (andnobody is talking about): burning wood in a power plant.


The devil is always in the details in schemes like this. Lets presume that you could actually build the hypothetical rooftop system for around $18k. I’ll bet that doesn’t include any costs of upkeep. It doesn’t include the costs of actually operating the system, either : cost of feedstocks, cost of gathering those feedstocks, cost of refining the crude biodiesel product to make it usable, cost of collecting and disposing of the waste products, and we can’t forget that our benevolent government wanting their tithe… the road taxes they normally collect at the pump! And, of course, how many people are going to want to live next door to somebody who is running a small fuel refinery on their roof and in their garage?
The only practical way to make something like this cost-effective is to do it on a massive scale, and biological processes don’t scale nicely.
Just my $.02

Frederick Davies

Why do they need pipes between the power stations and the “algae stations”? Why not let the atmosphere do the transporting? The algae does not need to “carbon-trap” the very same CO2 molecules the power stations emit, just some poor random CO2 molecules from the atmosphere in a quantity similar to those emitted; or are the enviro-nuts so out-of-it now that they can distinguish between good natural CO2 molecules and bad man-made ones? Besides, apart from the land-use feasibility issue, can these algae work on atmospheric concentrations of CO2 or do they need greater concentration for efficiency? If the latter, how do they plan to concentrate the CO2? Have they invented a carbon-neutral pump system? Those engines that are attached to the pumps are going to need fuel too, you know.


Algal fuel is an established and efficient process to extract money from investors and taxpayers.

Pierre Gosselin

Looks incompetence by the US Federal Reserve and global energy policy officials is coming home to roost big time.

Pierre Gosselin