the Air Vent

Because the world needs another opinion

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.

Nobel Prize Physicist Needs a Calculator

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.

http://www.unh.edu/p2/biodiesel/article_alge.html

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

Link HERE.

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.

watt-meters-per-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

4190 gallons

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.

—-

My conclusions:

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!



33 Responses to “What About Algae Biofuel Hype”

  1. Raven said

    Jeff,

    Water is an input to the photosynthesis process and I suspect that producing 161,000,000,000 gallons of *liquid* fuel from algea would required at least that much water.

    It seems to me we would run out of water long before we ran out of land.

  2. eksith said

    I think looking at hydrogen production from algae is more productive at the moment.
    The problem with biofuel is that it’s still being “burned”. Which isn’t going to help matters in the long run.
    And hydrogen production from fossil fuels takes us back to square one.

    Meanwhile compressed hydrogn cars like the Honda FCX Clarity is already available in California and the small number of hydrogen filling stations already see some business.

  3. paminator said

    Jeff- Great post!

    I spent a little time looking into Algae biodiesel this summer because of recent VC interest in this technology. I came to the same conclusions as you did. In fact, my estimates of efficiency were much lower than your 6%, more like 1% once you account for the process and equipment used to contain the algae. The pond-based algae experiments demonstrated much less than 1% efficiency.

    I think the biggest problem with algae efficiency is that it does not like to grow in high brightness environment (and I say this as a Florida pool owner with some experience with inadvertently growing algae crops in the pool). The highest efficiency photosynthetic plants generally love to be in the sun, but they are not algaes. Second, the high gallon/acre claims I found are based on using algae growth fluids contained in tubes or bags, but fill factor is not discussed, and the highest claims are from VC startups, which are most certainly questionable sources.

    Cost estimates are all nonsense because nothing approaching a commercial scale experiment has been built or operated for any length of time.

    I look at it as yet another renewable energy boondoggle used as a vehicle by VC investors to collect fed and state handouts to pave the way to 2 or 3 comma net worth.

  4. retired engineer said

    I was a fan (sort of) biodiesel until I read this. Even if your numbers are off by a factor of 2 (8k gal/a) it doesn’t make sense.

    Neither does hydrogen. You have to make it, from water, natural gas, or bio. All take energy. Then you have to transport and store it. As Hamlet said, “there’s the rub”. It takes energy to compress or liquify H2. Energy you don’t get back.

    Maybe we can convert coal to gasoline?

  5. Terry said

    I’m not a fan of using foodstocks to distill gas/diesel, but ran across an article in the local paper about a college thesis that spawned Ever Cat Fuels, which uses a completely different process to turn various animal/vegetable/algae oil into diesel via a catalyst (ever cat is short for everlasting catalyst) reactor. Google either Ever Cat Fuels or Mcgyan biodiesel process for details.

    I’m not associated/affiliated with them, but think the process looks interesting compared to current biodiesel methods. Was/am curious if that was bundled into the other bio results.

  6. Clark said

    I am a plant biologist, and I can tell you one number that you are unrealistically optimistic on.

    The losses involved in synthesizing oils are extremely high.

    The initial products of the light reactions are ATP and NADPH, and producing them involves a large number of steps, none of which is even 50% efficient (efficient in this case referring to the amount of available free energy captured in chemical bonds). ATP and NADPH are used to drive CO2 fixation, in the eventual form of G3P, requiring over a dozen enzymatic reactions, many of which is less than 50% efficient. The G3P is converted to acetyl CoA, which can then be shuttled to oil biosynthesis. Again, many steps involved (e.g., the carbons on the oil chains are added 2 at a time). This is not to mention that the algae have to maintain all sorts of other biological processes (osmotic stability, ion gradients, organelle biosynthesis, transport of intermediates). Think about people – about 2/3rds of the energy you expend is simply to maintain ion gradients across various membranes.

    Bottom line is that of the available energy in the photons of light, only a very small percentage will eventually end up in the chemical bonds of the oil.

    Of course, there is a completely separate issue that it would require a lot of energy to maintain algal forms the size of Connecticut, require a huge infusion of fertilizers, a ton of water, and energy investments to harvest the algae, separate the oils, and then convert them into a usable form.

  7. Mike D said

    Jeff: we could cover the gulf of Mexico with floating docks and use wave powered conveyor belts to transport algae to Texas refineries. Just think witth the golf covered we would have max sun and be close to refineries. Plus the advantage of reducing damage to the coast from hurricanes. Don’t forget the would help clean the excess chemicals from farms up river cause the algae could use the food. The smell might be a littke much but who needs to live on the coast and who really cares about Texas and Mexico. I think we should promote this idea with the fuel companies or find out what all these people doing this kind of study are smoking,drinking, or popping.
    Thanks for your insite and Happy New Year (or is that politically incorrect now)

  8. Jeff Id said

    Clark,

    Very nice. It’s good to have experts around.

    So would you mind educating us a bit about what you would suggest for photosynthesis efficiency. Do I have it within reasonable limits?

    Also, do you have a guesstimate than mine for the percent energy in a 50% oil algae beast that actually goes to oil?

  9. Don Shaw said

    Jeff,
    As another has already stated this is a great post.
    As an engineer who has worked in the energy business for over 45 years, I am constantly amazed at the wild claims for “alternative” fuels. Although I currently have a lot of exposure to commercial attempts to make ethanol and other liquid fuels from cellulosic feed stock, I had no knowledge of the Algae biofuels and your post is very informative.

    I am convinced that all the Hype about alternative fuels is primarily a diversion to deceive the masses into believing that there are near term viable alternatives to Fossil fuels. Our government is handing out tax $$$ to eveyone and his brother for projects that are devoid of basic economics and sound engineering principles. Also there is extensive duplication of efforts. The DOE needs someone like you to make some sensible calculations like you have made before giving the $$$ away.

    As to “our incoming science adviser”, it was reported that he has been working on alternative fuels for years. My question is what has he accomplished in the alternative energy over all those years? Why are there no visible results for all the money spent over those years since he is supposed to be so great? Why doesn’t the MSM ask these questions rather than slobber over Obama’s nominations?

    Again, great post, very informative with lots of sensible data, calculations, and assumptions.

  10. Eric Adler said

    Thanks for your analysis.

    Briggs tacitly admitted that 15,000 gal/acre was a bit high, and he finally settled for 5000 acres, which is in the ballpark of the 4150 that you calculated.

    He says,
    “..But, consider that even if we are only able to sustain an average yield of 5,000 gallons per acre-year in algae systems spread across the US, the amount of land required would still only be 28.5 million acres – a mere fraction still of the total farmland area in the US”

    Stephen Chu got $500M from BP for his Helios project, which included technology to bioengineer algae, so the research must be worth doing.

    Incidentally there are some startups which are being funded by venture capitalists in the Silicon Valley.

    http://www.pbs.org/newshour/bb/science/jan-june08/green_05-29.html

    We will see whether anything comes of this in a few years. This may not be as far off as you would have us believe.

  11. Don Shaw said

    Eric Adler says
    “Stephen Chu got $500M from BP for his Helios project, which included technology to bioengineer algae, so the research must be worth doing.”

    If that’s your measure of Chu’s accomplishments on the alternative energy I cannot argue with you on his ability to get funds. However, my standards are quite different based on my experience. I would like to know what specific contributions to the energy supply have been realized from Dr Chu,s efforts to date to justify his apointment as Energy Czar. They may be significant but I have not heard of any yet.

    Billions of dollars have been spent on energy supply by the government and private energy companies over a number of years with little results. I have personally worked on many projects over decades and continue to do so. Based on my experience it is either naive or dishonest to lead people to believe that there are quick solutions that will provide an alternative to liquid fossil fuels for transportation, if we only spend more money. Worse yet it is irresponsible to risk the economy on technologies that remain to be proven and to curtail (tax) the use of fossil fuels before alternatives are demonstrated. If it were so easy, a solution would have already been found years ago since the quest for energy has been ongoing. Just look at the ethanol situation and the Congressional mandate to produce even more despite the obvious problems and limitations. This is the kind of energy policy that Congress will likely squander the proposed 150 billion tax dollars. Does it make sense to cut down trees to make ethanol which is the nearterm feedstock?

    Eric, you reference BP and other venture capitalists suggesting that they know better. I remind you that a lot of smart people trusted Bernie Maydoff and lost up to 50 billion dollars. Instead of trusting Chu, BP should have invested their 500 M dollars in maintenance on the Alaska pipeline, but that would not have given the public the impression that they are really green and not dependent on fossil fuels. Besides it is obvious that Energy corporations realize that congress plan to punish use of Fossil fuels so they need to change the business model even though it does not make sense from the pure energy viewpoint.

    This Helios information was taken from their website; I don’t expect any near term results to satisfy our energy needs. Hope I’m wrong:

    “The Helios effort is a solar energy initiative at Lawrence Berkeley National Laboratory (LBNL) and UC Berkeley. The primary goal of this effort is to develop methods to “store” solar energy in the form of renewable transportation fuel. Several approaches under investigation include the generation of biofuels from biomass, the generation of biofuels by algae, and the direct conversion of water and carbon dioxide to fuels by the use of solar energy.”

  12. KuhnKat said

    Jeff,

    haven’t read you whole list of articles yet. Have you done anything on the genetically modified e-coli?

    http://www.dailytech.com/Startup+Has+E+Coli+Pooping+Black+Gold/article12649.htm

    http://www.ls9.com/news/FAQ.html

    these guys apparently have a contract with the military for a pilot plant in place of the Congressional cancellation of Coal Liquefaction.

  13. Eric Adler said

    KuhnKat,
    It was an interesting article.
    It may provide an better alternative
    versus making ethanol from sugar, but it still requires sugar. It can’t make use of plant waste.

    It is a different concept from using algae to produce a fuel directly from sunlight, CO2 and whatever other nutrients are required. It does illustrate the power of genetic engineering that the Berkeley Lab is trying to employ to produce biofuels more efficiently.

  14. Richard M said

    I would like to re-iterate my comments on this topic previously. I don’t believe algae is an end-all solution. Jeff’s numbers make that clear. However, it may be able to help in several ways.

    First, it appears to be the most efficient bio-fuel available. Much more efficient than food crops. Moving from food crops to algae will help keep food costs down.

    Second, placing algae farms near coal/gas electrical plants provides a means to eliminate carbon emissions by feeding the carbon to the algae. This essentially eliminates the carbon footprint from these power plants. Naturally, the emissions still occur when the oil is used, but that is already happening when crude oil is burned. Essentailly, you get double the energy per unit of carbon (not exact, I know).

    In addition, there are residual feed stocks produced when the algae oil is extracted. This reduces the demand to utilize potential food crops to feed cattle, etc. which could provide more exported food to other countries and help balance our imports.

    Finally, I can see bio-feuls like algae helping reduce our dependence on foreign oil. As the analysis here makes clear, algae is not a replacement for oil, but it could certainly take a big bite out of the requirement for imported oil. Yes, it will cost more but maybe not more than a highly taxed barrel of crude. However, I still think it can be “part” of a long term solution.

  15. Curt said

    Jeff — I know, not a major part of your post but when you say,

    “Driving on electric is a horribly inefficient solution due to generation and transmission line losses”,

    I have to disagree with you.

    Electric generation from fossil fuels typically has a thermodynamic efficiency of 40 – 50%, with some new plants approaching 60%. Compare this to 20 – 25% for a gasoline internal combustion engine, and 30 – 35% for a diesel ICE. Also, the preparation of fuel for ICEs consumes a lot more energy than for electric generation. Even with subsequent transmission losses of several percent, you do come out ahead energy-wise with electric propulsion of vehicles. (Not by enough to justify the additional cost of the vehicle in straight economic terms, however.)

    This small but real advantage was never the main reason behind the pushes toward electric vehicles. The key reason that California has been pushing for it is that the burning of fuel for electric generation is so much cleaner than in ICEs.

  16. DeWitt Payne said

    Curt,

    There are significant losses involved in charging and discharging batteries, internal resistance, e.g. The faster you charge or discharge, the worse the loss. Generally there is a trade off between internal resistance, maximum depth of discharge and battery life. Then there are the losses from conversion of AC to DC and possibly back again. The Tesla electric sports car, for example, uses a three phase AC motor. I suspect your 60% efficient power plant is either natural gas fueled or efficiency is calculated before the scrubbers, which can make a substantial hit on overall efficiency.

    A reversible heat engine requires a 750 K hot reservoir, assuming a 300 K cold reservoir, to achieve 60% efficiency. That’s 100 K hotter than I could find a steam table calculator to estimate the pressure. A real heat engine would have to be a lot hotter than that.

  17. DeWitt Payne said

    Why not burn the algae? Well, as harvested, algae is (are?) wet and you’ll lose energy converting the residual water to steam. So dry it. How? Using sunlight will require even more acreage and there are bound to be oxidative losses in the drying process and will still leave some residual water. Refining the algae to oil will also lower the overall efficiency.

    As pointed out above, the 6 to 10% efficiency for photosynthesis is just for converting CO2 to carbohydrate, i.e. removing one of the oxygen atoms and replacing it with two hydrogen atoms. Removing and replacing the second oxygen atom and assembling the hydrocarbon chain is much harder. I’ve seen somewhere that in animals, the conversion of dietary carbohydrates to fats is only about 16% efficient in terms of calories in to calories out.

    I’ve heard of a process to produce beta-carotene, a much higher value product, from algae. It was unsuccessful.

  18. JeffId said

    Curt,

    I wanted to add that the power transmission line losses are actually on the order of 50% not a few. It’s something not well known but a huge portion of the generated electricity is lost to heating power lines.

    If you include the 50% losses along with the battery charging losses and eventual electric motor losses its a net negative.

  19. Curt said

    No, electric transmission and distribution losses overall are about 7% of generated power — about 4% line losses and 3% transformer losses. See for example:

    http://climatetechnology.gov/library/2003/tech-options/tech-options-1-3-2.pdf

    You do lose a few percent in each of the following stages: charging and discharging the batteries, AC-to-DC rectification, DC-to-AC inversion, and motor copper and iron losses. But the important word in this paragraph is “few”. Even if you add all of these together, the fact that the thermodynamic efficiency of burning fuel in electric generation is twice that of a gasoline engine means you come out ahead.

    (I design electronic motor control systems for a living, so I am directly familiar with these issues. I am writing this while taking a break from working on thermal issues of increasing the switching frequencies of the power transistors driving motors. Most of my work is for industrial systems, so I do not have a direct financial stake in the success of electric vehicles, but I have worked on about a dozen electric vehicle projects over the last 20 years, so I am keenly aware of the promise and problems of the vehicles, and this is not one of the problems.)

    Interestingly, one problem with electric vehicles is that they are so efficient at the vehicle that you cannot assume they produce enough waste heat to keep the passenger compartment warm enough on a cold winter day.

    Dewitt — I’m not sure what you are trying to say in your second paragraph of #16. There is no such thing as a “reversible heat engine”. A heat engine is fundamentally irreversible. Perhaps you are talking about the theoretical maximum thermal efficiency of a (fictitious) Carnot cycle engine, which would require a 750K source and 300K sink to achieve 60% efficiency. But combustion for both electrical generators and ICEs produces source temperatures far, far above 750K (which means neither gets very close to Carnot efficiencies, but electric generation gets far closer.)

  20. Jeff Id said

    Ah, Curt you may be right, I love having smart people around. I don’t have time today to look for a new link, I work long hours out here.

    However, I am traveling with the electrical engineer I used for a source. You may have messed up his day…He, He :) ’cause he’s been telling me 50% for years.

    I was planning to do a post on electric drive cars in the future, just to look at feasibility.

    Since you are now the resident expert on electric drive systems, I have a few questions. What percent would you assign for conversion of electrical power to mechanical motion in an ‘efficient’ electric motor. Also, if you don’t mind what are the losses you would expect in an ‘efficient’ inverter system for an electric car.

    In my college days I built an electronic control system for a hybrid , but that was a long time ago.

    BTW:I do question your few percent for battery charging efficiency. Again, I haven’t done my post yet, but my recollection is less than 80% in perfect temperatures. What sort of battery are you assuming?

  21. Curt said

    Jeff,

    A bunch of questions…!

    Batteries are not my particular field of expertise, but I do know some things you have to look out for as you research this topic:

    1. Some sources will quote charging efficiency of a battery, and some the overall charge/discharge efficiency (and they may not be clear on which they are quoting).

    2. Some charging efficiency figures are just for the batteries, and some include charger losses (and they may not be clear on which they are quoting). Charger losses include AC-to-DC rectification and any step-up or step-down losses.

    3. The efficiency of chargers for small electronic devices (e.g. cell and cordless phones, laptops, etc.) is pretty low because the small amount of energy processed does not justify the cost of making them more efficient. These values should not be used for vehicle charging analysis.

    4. Charging efficiency of the batteries depends on many things, including the charging rate and the level of charge in the battery. The last few percent of charge in a battery can be pretty inefficient. In a cell phone, you would tolerate that inefficiency, but in a car, you would not.

    5. Different battery types have significantly different efficiencies. From what I can tell, lead-acid is pretty good, nickel-metal-hydride is pretty poor, and lithium-ion is excellent.

    I believe all present on-the-market hybrids use NiMH batteries, but all serious plug-in hybrids and full-electrics plan to use Li-ion because of the higher energy density.

    Tesla Motors reports an overall charge/discharge efficiency, including charger losses, of 86% for their Li-ion battery packs. (I found a comparable figure for lead-acid systems of 76%.) They break this down into a charger efficiency of 93%, and battery charge/discharge efficiency of 93%.

    Inverter efficiency and motor efficiency can each reach 95% or possibly a little more, but will not always be this high. A lot depends on the use pattern. Average inverter efficiency in the low 90s and motor efficiency of 90% is probably reasonable. Remember that an electric motor does not need to idle and that regenerative braking can recapture a lot of energy.

    In Tesla’s analysis, they do not try to calculate percentage efficiency after the battery output. Instead, they report km/MJ for certain driving patterns and compare this to gasoline-powered cars for the same driving pattern. This looks to me like a reasonable approach. (One thing I do not find reasonable in their analysis — they use the highest known efficiency of 60% for electrical generation; a very small percentage of electrical power is generated this efficiently.)

    An interesting place to get started:

    http://www.veva.bc.ca/wtw/Tesla_20060719.pdf

  22. Oil from algae is the wave of the future. And always will be.

  23. Jeff Id said

    #22 – At least until it becomes the boondoggle of the past.

  24. spikeanut said

    I used to feel very positive about next-gen biofuels (e.g. cellulosic ethanol, algae biodiesel). However, over the past year, I’ve become increasingly convinced that the future of transportation lies with electrification rather than improved liquid fuels.

    That’s not to say that natural gas and next-gen biofuels can’t play a part, but the focus going into improving battery technology right now leads me to believe that this is ultimately where things are headed.

  25. meThem said

    Questions questions.
    Which is more efficient? Producing hydrogen to store energy or putting the energy in batteries? That is for vehicles. I suppose batteries are more cost effective at the moment. Then what about super capacitors would that change the game? But would it still be more efficient to use petroleum distillates to move vehicles. That is use efficient methods to generate electricity as needed to move down the road.

  26. jObLO said

    “Solar panels blow away the efficiency of photosynthesis as I have pointed out before some exceed 30%”

    This is not true panels used today can’t exceed 12% efficiency maybe panels using exotic materail may, but it’s far from production in a short or medium term.

    Do your own esearch on the net and you will find out 12% is the maximum. You do the same thing some algae growers do; exagerate

  27. Jeff Id said

    Research grade solar can exceed 30%.

  28. kwik said

    Let them build a demo-plant. look at man-hours to maintain it.

    Lets see the waste-buildup. Show us where the water comes from.

    And so on. Will be interesting.

  29. Jeff Id said

    #28, The amazing thing is that public companies dare to make such ridiculous claims. They’ve got peoples money tied up in these things- yet haven’t got any physical chance of achieving their goal.

  30. Quality Information Thanks!

    I have bookmarked your site, if you get a chance please take a look at our site

    http://www.bio-partners.co.uk

    there is some more information you may find useful in our members area!

    Warm Regards,

    Dougie

  31. JamesD said

    I agree with the other posters, you are too optimistic. The efficiency you use is to produce carbohydrate. You then have to convert that to the oil.

    On that basis, this looks like a loser. But then factor in pumping water through a surface area the size to 2-3 Arizonas. Then you have to harvest this algae and separate out the oil. How exactly is that going to be done on a large scale? Then there is the fertilizer required.

    Might make sense on a small scale in niche markets, but this isn’t THE answer.

  32. Jeff Id said

    #31, If you’re referring to the post rather than some commenter, this post absolutely destroys any relevance for algae biofuel or any other biofuel for that matter. It was done best imagined case for algae and there is still no hope it could work. Biofuel is a dead issue in my opinion and some of these company owners should be looking at prison time for what they did to their investors.

  33. william mccusker said

    You state that the mean latitude of Arizona is 47.5 degrees. I believe this is in error. The latitude of Boulder Colorado is 40 degrees.

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