One of the fastest ways to tell if a company is legit is to check their claims against basic laws of physics, chemistry, etc. In the algae world, a company’s predictions of how many gallons of biofuel they can generate per acre per year is a good place to start. Obviously, there’s a temptation to exaggerate to generate interest, so it tells you a lot about a company where they put this number. For example, our friend GreenFuel said they would generate 15,000 gallons, to the derision of at least one major algae scientist. It’s also good to know the limits on photosynthesis in any case.
At the 2008 Algae Biomass Summit in Seattle, I saw an excellent presentation entitled “Theoretical Maximum Algae Oil Production,” by Kristina Weyer of Solix Biofuels. The details of the analysis are somewhat complicated, but the basic idea is straightforward. Algae, like all plants, convert the energy of the sun into chemical energy, some of which we can take and use as fuel energy. So you’re limited by the amount of sunlight reaching the location of your algae farm, and by the efficiency with which the algae convert that sunlight energy into usable fuel energy. The former is determined mainly by location, varying by about 2x between the highest tropical/desert zones and the temperate parts of the U.S. and Europe. Only 45.8% of solar radiation is usable by plants (though there are some odd algae capable of using infra-red or ultraviolet light, and fungi capable of absorbing energy from nuclear radiation…sorry I’m getting carried away).
The efficiency of algae in making fuel varies much more, and can be to some extent improved by engineering. It depends on five basic factors, all of which apply equally to open ponds and even the cleverest of photobioreactors:
- Light transmission efficiency, or what fraction of the light actually makes it into the culture; this is determined by the reflectivity of the surface of the pond or photo-bioreactor, and any absorption from dirt or algae clinging to the inside of the PBR. In a well-designed, well-maintained system, this loss might be 10%.
- Photon absorption efficiency, a combination of the efficiency with which the algae’s photosynthetic molecules convert the electromagnetic photon energy into chemical energy, and the rate at which this chemical energy can be passed to the reaction center, where it is stored by cleaving a CO2 molecule. The conversion efficiency is always less than 100% because the photochemical molecules only capture a specific amount of energy from each photon, wasting a sizable amount of energy from higher-energy photons. This is an impossible-to-avoid 24% loss. The capturing of photons and passing them to reaction centers is performed by a constantly-shifting ensemble of generally colorful molecules unique to each type of algae (giving them a wide range of colors, from pale yellow to blood red to purple-black). Each time the photonic energy is passed from one molecule to another, some energy is lost. Excess photons can also disrupt the process of passing the energy along, so efficiency drops with increased light level. Many groups are working on fixing this problem with genetic engineering; the Aquatic Species Program final report estimated that a 3x improvement in photosynthetic efficiency over wild algae should be possible through antenna mutants, though this much improvement has not yet been demonstrated. We’ll talk more about this stuff later. Since we’re interested in ultimate possible efficiencies here, we’ll assume that you’ve engineered or bred the heck out of your algae, and gotten the loss due to all these mechanisms to a fantastic level of 50% (90% loss is not unusual for wild algae in direct sunlight…).
- Fundamental photosynthesis quantum efficiency, or the number of photons that have to make it through all the previously-mentioned processes to break up one CO2 molecule and make “biomass” (i.e., a simple sugar building block). In the process, about 73% of the photonic energy is lost. There is no fix for this, barring the creation of a wholly new photosynthetic pathway, which is *way* beyond current bioengineering technology.
- Biomass accumulation efficiency, or the losses incurred in the cell’s metabolism converting the simple sugar from the last step into actual, living biomass, and energy used up by the algae just living, especially at night (because algae don’t own the night™). 40% loss is a typical number, and there aren’t many ideas for how to improve this, because algae are, after all, living, squidgy things, and burn calories just like we do.
- Lipid percentage, or what fraction of the biomass is actual oil. Up to 70% has been obtained in labs, but in practice, consistently getting 50% oil would be a great achievement.
Combining these very optimistic assumptions with actual weather data gives a maximum output of 6,500 gallons per acre per year for an extremely sunny place like Phoenix, Arizona. Anyone claiming more than this should be looked at with real skepticism.
If you throw any sense of realism to the winds, and assume that light transmission, photon absorption efficiency, and biomass accumulation efficiency are all 100% — in effect, assuming a science-fiction organism that does nothing but make oil, with absolutely no internal losses, and no metabolism at all, with the maximum possible 70% oil content, growing at a fictional spot on the equator where there are never any clouds, you’d get a fantasy yield of 53,000 gallons of oil per acre per year.
So how come Valcent, Inc. is claiming they can generate 100,000 gallons of fuel per acre per year?
Valcent and their Vertigro system (pictured above) are prominently featured on the YouTube and many “green energy” sites, and have appeared on CNN and other TV shows, in every case to breathless enthusiasm. Apparently, no one thought to do the back-of-the-envelope calculation that would show that they are expecting us to swallow a claim that is simply absurd.
But they are not alone.
Joule Biotechnologies says that their genetically engineered photosynthetic mini-beasts are not algae, but the above argument applies to any photosynthetic organism, so their claim that they will be producing 25,000 gallons of ethanol and 15,000 gallons of diesel per acre per year should be a red flag for investors (not to mention that they are claiming they’ll have a pilot plant in on year, and commercial-scale production by 2012!). The fact that the organisms (which may be a type of mini-duckweed) are secreting the fuel instead of being harvested and processed changes the above calculation somewhat, but not enough. If the critters can be kept alive indefinitely producing the product, then the lipid fraction is effectively 100%. This still does not get you close to their claims for any realistic biological photosynthetic mechanism. Caveat emptor!
But the real clowns of the algae biofuel world have to be BARD — Biofuel Advance Research and Development, winner of an “Algaeprenuer 2009″ award from the National Algae Association:
“BARD’s closed loop photo-bioreactor technology can produce 66 million gallon of algae oil in 7 acres of land,
which is 8,571,428 gallon of algae oil per acre. The pilot facility will begin by producing 43,070 gallons of algae oil / biodiesel per annum using only six modules of photo-bioreactors covering 84 square feet.”
This was a bit much, and got them some heat from some quarters. In reply to their critics, CEO Surajit Khanna wrote the following:
“Why you or your other folks are comparing our numbers from our technology to open pond based algae technology? Completely bogus. We are not even talking here about open pond nor using sunlight. Because you all don’t know what this means so you are challenging our figures.
[Whether] you or your people believe in our technology or not – how does that matter to BARD? We are not seeking any funding from you nor seeking any help. Why would the public care about your comments? We don’t have to prove to you anything. Just for your information our data is based on our proven lab scale technology. Our scientist has been working on this technology since 1957. The same lab scale [has] been transformed to pilot-plant scale.”
To which, Eric Wesoff of Greentech Media makes the point that “if their scientist has been working on this since 1957, he’ll need to work fast to see the results of his efforts.”
To help out this poor scientist, I have done my best to envision what this fantabulous facility would look like:
And it would be extra cool because it would glow like crazy at night, using the entire energy of at least three large coal-fired power plants.
(Optional calculation proving above statement: (146MJ/gal * 66Mgal)/(365*24*3600) = 300MW; at a high light-to-biofuel efficiency of 10%, this would mean 3GW of light from the LEDs. 1GJ is a typical value for a regional coal-fired plant in the U.S.)
I guess the $40M they claim to have raised is just a down payment.
It’s kind of sad that they’re building it in Ohio, where such a monument to the human capacity to achieve untold gallons per acre would not get many visitors.
As a last, lovely touch, when this story first broke, the last time I tried to visit their website my browser warned me that it was attempting to install malware on my computer (luckily, I use a scriptblocker). Infer what you will.
So, are there any legitimate algae companies? Well, there are many that don’t require new laws of physics to reach their projected yields. The smart ones are focusing on the real issue of algae biofuel — the economics.
Next: Is it possible make $$$ growing algae for biofuel?
P.S. I always like it when people posting use numbers to justify their arguments, even if I don’t agree, and even if it’s not particularly informed. Check this recent assessment of the energy balance of algae biofuels, esp. the comments 😉