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.
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!!!
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?
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.
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.
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.”
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.
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.
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.
I can hear it now…..too little CO2 causes man made ice age.
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.
Interesting.
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!
“…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.
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.
http://www.efuel100.com/t-technology.aspx
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.