What About Algae Biofuel Hype
Posted by Jeff Id on December 31, 2008
I’ve been having a discussion with Eric Adler on biodiesel again on another thread.
I complained about our incoming science adviser under the Obamessiah acting as a politician by supporting untenable green energy policies. Eric isn’t a troll and deserves good credit for his points. He gave one link which I found interesting. Check it out.
It is from the university of new hampshire bio-diesel group. Something which should cause us to consider it with a skeptical (not critical) eye. After all if they found bio-diesel unworkable the wouldn’t have much to do. Think of it like asking an oil company about its opinion on oil’s role in global warming. Still these guys may have a point but as I have calculated a number of times on my blog, the devil is in the numbers. UNH Biodiesel (I’ll call it UNHB) has been good enough to provide calculations equivalent to my own so let’s see where the differences are.
Per the Department of Energy’s statistics, each year the US consumes roughly 60 billion gallons of petroleum diesel and 120 billion gallons of gasoline.
From the DOE we are currently up to 140 billion gallons of gasoline due to increased consumption and planning for less than 200 is unreasonable because of growth but let’s assume 140.
The UNHB article recommends converting to diesel because of a claimed 35% increase in efficiency. Here’s what I find.
139,000 – 147,000 BTU/gallon energy content in diesel
125,000 BTU/gallon energy content in gasoline
126,000 BTU/gallon biodiesel
The article claims the following:
So, if all spark-ignition engines are gradually replaced with compression-ignition (Diesel) engines for running biodiesel, we wouldn’t need 120 billion gallons of biodiesel to replace that 120 billion gallons of gasoline. To be conservative, we will assume that the average gasoline engine is 35% less efficient, so we’d need 35% less diesel fuel to replace that gasoline. That would work out to 78 billion gallons of diesel fuel. Combine that with the 60 billion gallons of diesel already used, for a total of 138 billion gallons.
The higher efficiency of diesel will reduce our gas from 140 billion to 91 billion gallons. This seems reasonable since energy content is the same as gas part of the 35% efficiency assumption is a conversion to diesel energy units per gallon which I’ll discuss later. They combine that with 60 million already used diesel , I couldn’t find the doe reference for diesel in the standard report. It did show the doe fuel oil at 117 billion gallons. I’ll use their number of 60 billion gallons multiplied by the increase in gasoline of 140/120 billion gallons to get 70 billion gallons today. The total then is 91+70 or 161 billion gallons of oil per year.
The UNHB guys then make the correction from the energy density of bio to diesel energy concentrations. Here’s the text.
Now, biodiesel is about 5-8% less energy dense than petroleum diesel, but its greater lubricity and more complete combustion offset that somewhat, leading to an overall fuel efficiency about 2% less than petroleum diesel.
First from the numbers above I found 139-147,000 btu/gallon for diesel and 126,000 for biodiesel for a difference of 10 to 16%. This made the spidey sense tingle, I am sure they have some form of biodiesel which has a higher energy concentration than my link but they must be using best case.
Now they make the conversion from diesel gallons to biodiesel gallons as only a 2% change in efficiency. From my own experience, I disagree with these numbers pretty strongly but the change is small enough (between 2% and 16%) we can ignore it for our purposes. After all what’s a few billion gallonss between friends.
So 1.02 x 161 billion gallons is 164 billion gallons.
The next paragraph is a bit of editorializing by the UNHB, just to let my conservative readers understand the mindset of the people writing this article.
I would like to point out though that a preferable scenario would include a shift to diesel-electric hybrid vehicles (preferably with the ability to be recharged and drive purely on electric power for a short range, perhaps 20-40 miles, to provide the option of zero emissions for in-city driving), and with far fewer people buying 6-8,000 pound SUVs
Driving on electric is a horribly inefficient solution due to generation and transmission line losses but I’m not going to cover that here, but it is an unscientific opinion as it goes against the facts. The less people buying SUV’s is what bothered me.
There are two steps that would need to be taken for producing biodiesel on a large scale – growing the feedstocks, and processing them into biodiesel. The main issue that is often contested is whether or not we would be able to grow enough crops to provide the vegetable oil (feedstock) for producing the amount of biodiesel that would be required to completely replace petroleum as a transportation fuel.
This paragraph is the crux of the disagreement between Eric and myself. It recognizes what I have calculated an pointed out in my previous posts as a the main issue. The amount of area required to produce the fuel is the main issue. Well the UNHB has the calculaitons which show it can be done. I have calculaitons which show it can’t. Let’s see where we collide, I’m writing this as I go so maybe it won’t be as bad as I expect.
At heart, biofuels are a form of solar energy, as plants use photosynthesis to convert solar energy into chemical energy stored in the form of oils, carbohydrates, proteins, etc.. The more efficient a particular plant is at converting that solar energy into chemical energy, the better it is from a biofuels perspective. Among the most photosynthetically efficient plants are various types of algaes.
I like this next paragraph.
The Office of Fuels Development, a division of the Department of Energy, funded a program from 1978 through 1996 under the National Renewable Energy Laboratory known as the “Aquatic Species Program”. The focus of this program was to investigate high-oil algaes that could be grown specifically for the purpose of wide scale biodiesel production1. The research began as a project looking into using quick-growing algae to sequester carbon in CO2 emissions from coal power plants. Noticing that some algae have very high oil content, the project shifted its focus to growing algae for another purpose – producing biodiesel. Some species of algae are ideally suited to biodiesel production due to their high oil content (some well over 50% oil), and extremely fast growth rates.
Let me translate this. The aquatic species program did research on using algae to sequester CO2 from ‘big’ coal. Finding that the amount of energy produced by the coal plant couldn’t be recaptured by sunlight without a massive amount of area they switched directions. Yeah it’s a bit sarcastic but what were they thinking? If you have built an algae factory capturing 100% of the energy output of the coal plant why not just burn algae? The whole proposal is unreasonable, I wonder who signed off on it.
This is where the numbers get interesting.
NREL’s research showed that one quad (7.5 billion gallons) of biodiesel could be produced from 200,000 hectares of desert land (200,000 hectares is equivalent to 780 square miles, roughly 500,000 acres), if the remaining challenges are solved (as they will be, with several research groups and companies working towards it, including ours at UNH). In the previous section, we found that to replace all transportation fuels in the US, we would need 140.8 billion gallons of biodiesel, or roughly 19 quads (one quad is roughly 7.5 billion gallons of biodiesel). To produce that amount would require a land mass of almost 15,000 square miles. To put that in perspective, consider that the Sonora desert in the southwestern US comprises 120,000 square miles.
National Renewable Energy Laboratory, is a government organization who’s existence depends on practical renewable energy. There can be no question that they have a horse in this race. This group has determined that we can get 7.5 billion gallons of biodiesel from 500,000 acres of land. This means 15,000 gallons per acre. WOW! thats a bunch.
Let’s do the numbers:
15,000 gallons/acre year at 126,000 btu/gallon = 1,890,000,000 btu/acre year captured in biofuel oil. The best algae are 50% oil, so at least half the energy used in making an algae goes into biological processes. We then need to capture 3,780,000,000 btu/acre year by sunlight through photosynthesis.
How much sunlight falls on an acre of desert in a year.
Let’s use best case from arizona of 6.5 kwh/m^2 day. This includes a latitude tilt so we need to multiply by the cosine of the latitude for adjusted numbers.
I’ll convert meters to acres and kwh to btu and days to years next.
6.5 kwh/m^2 day *365 days/year *3412 btu/kwh * 4046 m^2/acre =32,742,000,000 = 3.27 e10 btu/acre/year
At Arizona the mean latitude is 47.6 degrees so our number 3.27e10 is multiplied by cos 47.6 =2.20e10 btu/acre/year as specified by the latitude tilt in the title of the graph above.
We would need to capture then 3.7e9 btu/acre out of an available 2.2 e10 btu/acre which amounts to 17% of the available solar energy per acre has to be captured by photosynthesis for the NREL claim to be true.
Let’s find some percentages from other web locations to see if 17% is reasonable.
Here is a link which claims 3% with literature citing a maximum of 10%
Here is a link which claims an absolute maximum of 6.6%
Wikipedia makes the following claim
The photosynthetic efficiency is the fraction of light energy converted into other forms of energy for use. Trees convert light in to chemical energy through the process of photosynthesis with a photosynthetic efficiency of approximately 0.2-0.5%. Other numbers reported range up to 6%, a more detailed analysis is required. By comparison solar panels convert light into electric energy at a photosynthetic efficiency of approximately 10-20%. The photosynthetic efficiency varies with the frequency of the light being converted.
Solar panels blow away the efficiency of photosynthesis as I have pointed out before some exceed 30%.
Here is an abstract which sets the absolute maximum of photosynthesis at 8-9%.
Keep in mind that these are the absolute maximum possible numbers. All are substantially below the 17% conversion required to meet the NREL claims. In fact they’re not even close.
Let’s look at actual algae results in gallons per acre.
Heres a quote from wikipedia
Algae: 2763 dm3 (liter) or more (~300 gallons per acre; est.- see soy figures and DOE quote below)
I also found a link which stated today’s production was 900 gal/acre but I can’t find the link anymore.
Let’s see some of the claims for future ‘potential’ production next.
Here’s a link which claims 1000 gal/acre with 5000 reachable.
Here’s a company which claims 10,000 gallons per acre
Here’s a company which claims 10,000 gallons per acre
Here’s a company which claims 1440 gallons per acre
Here’s a link from utah state which claims 10,000
Here’s a green blog claiming 15,000
Here’s a link claiming 4,000
Please feel free to add to all these links below, I’ll add them in.
Some blogs even claimed 100,000. What do my numbers show.
Assume an actual (very high) algae conversion efficiency of 6%.
Assume 80% of the light makes it to the algae on average (very high).
Assume Arizona light levels as above. 2.2e10 btu/acre available light.
Assume half of the light turns into oil (also high).
2.2e10 btu/acre * .06 * .8* .5 =528,000,000 btu/acre captured in oil.
At 126,000 btu/gallon this means the absolute maximum oil per acre which can be produced by algae is
As a high estimate.
If I take my 4190 gallons per acre and our need for 161,000,000,000 gallons per year. I get 38,425,000 acres required.
If I use more reasonable numbers for light level, conversion efficiency and oil production I get about double that. If I take into account spacing of the farms and other losses for infrastructure I can add another 25% required.
Arizona’s 114,000 miles sq = 72,000,000 acres.
So in the ideal situation we could cover 53% of arizona. In reality it would take at least 1.3 arizona’s to produce just our vehicle fuel.
From suggestions by several articles, actual production numbers are below 1000 gallons per acre. This would reuire 161,000,000 acres of land as a minimum and would result in an area at least 3 times that of Arizona to cover our requirements. An unacceptably large amount.
Our total current oil use is actually 317 billion gallons per year. That would take about 2.6 arizona’s to cover with the ideal number or about 6 arizona’s with current high efficiency production.
Cost estimates I found ranged from a reasonable $1.70 to as much as $15 per gallon. My impressioin was that $8 per gallon was more typical.
First the NREL numbers in gallons per acre are completely unreasonable. The energy just isn’t there for the fuel production. Companies claiming 15,000 potential gallons per acre are simply not being honest with the facts.
The covering of several states for biofuel would help reduce the CO2 output. My actual feel for the numbers says 3 to 6 Arizona’s minimum today when all factors are figured in, to create enough biofuel to replace our vehicle usage. Currently the lack of numbers on actual production is astounding, yet the claims are tremendous. If someone really demonstrates a 4000 gallon per acre system people should consider creation of a small production installation for evaluation purposes but it doesn’t look very likely to me.
Also, if the costs cannot get to a level similar to current oil production costs, the biggest CO2 savings will be in the form of economic collapse. Something liberals seem to have no fear of.
I therefore do not believe that this biofuel nonsense has anything to do with science, it is currently political redirection by politicians. Support for implementation of any biofuel at this point is non-practical. Even the research should be kept to extremely low levels until some demonstration of actual results works. I pointed out on my other post super algae biodiesel that the results must consider whether energy is introduced into the system as food. This alters the energy balance and makes it seem as though we have improved over the actual numbers. If this is the case 15,000 gallons per acre is possible but at least 11,000 of those gallons are being created somewhere else!