The Man Who Wrote the Book on Algal Biodiesel
Posted by Robert Rapier on May 17, 2007 - 11:22am
Topic: Alternative energy
Tags: algae, algal biodiesel, biodiesel [list all tags]
The following is a guest post by John Benemann. John has many years of expertise in biomass conversion, and previously co-wrote a guest piece on cellulosic ethanol. On the subject of biodiesel from algae, he literally wrote the book.
I originally wrote an article over a year ago in which I mentioned the potential of algal biodiesel. I still believe, as I did then, that biodiesel (or more broadly, renewable diesel) is a far superior fuel to ethanol for reasons I outlined in that essay. However, over the past year, the more I learned about the prospects of biodiesel from algae, the more it started to look to me like cellulosic ethanol: Technically feasible? Yes. Commercially feasible? Nowhere close, and the prospects don't look good any time soon. (However, as in the case of cellulosic ethanol, I believe the technology has some potential, so the government should fund the research).
This was a bit disheartening for me, because I had high hopes that we had an option for replacing a large amount of our fossil fuel usage. I no longer believe that, and recent work by Krassen Dimitrov (PDF warning) had reinforced my doubts. When I read the guest post by fireangel, "Has the Algae Cavalry Arrived", my first thought was "Nice work." My second thought was, "I should have jumped on this and investigated thoroughly eight months ago when those nagging doubts started to creep in." One nagging question I have had since I first read about biodiesel from algae is "Why would NREL terminate the project if the prospects really were good?"
But should there be any further doubts, here is a guest post from a man who knows as much about this subject as anyone else in the world. And he bears bad news for those who had visions of driving around in algae-fueled transportation.
--------------------------------------------
I saw with some interest the guest post on "Has the Algae Cavalry Arrived" posted by Heading Out and written by fireangel about the claims being made by GreenFuel Technologies (GFT) Corporation. I have some standing in this matter, both as Manager of the International Network on Biofixation of Carbon Dioxide and Greenhouse Gas Abatement with Microalgae (operated by the Int. Energy Agency, Greenhouse Gas R&D Programme) and also as a researcher in this field for over 30 years. My comments here are my own, of course, and don't necessarily reflect those of the GhG R&D Programme or others involved in the Biofixation Network. In brief:
1. The post by fireangel, based on the analysis by Dr. Krassen Dimitrov's, is generally correct, although some details regarding algae physiology and mass culture are arguable. However, those would not change the general conclusions of this posting. Well done!
2. The claims for biodiesel production rates being made by GFT, among many others in this field, exceed anything based on biological or physical theory, as also pointed out in this posting. They are truly bizarre.
3. The use of closed photobioreactors (>$100+/m2) for such applications is totally absurd.
4. I am on the record as stating that this is "It's bizarre; it's totally absurd." (see below article from the American Scientist last year, which quotes me to that effect. This was a correct quote, and in context).
5. Open ponds, at <$10/m2 can be as productive as closed photobioreactors. The arguments that closed systems are better than open ponds are incorrect - they both have their particular applications and benefits/drawbacks. It all depends on the situation and applications. The main difference is that open ponds are much cheaper.
6. Open ponds may plausibly be considered for algae biofuels production, but this assumes that indeed the required R&D is successful, a very BIG IF (but that is true of all R&D). But it is worthwhile trying, as we must try all plausible options. But we must also reject those that, as pointed out in this posting, violate first principles and have other major up-front failings.
7. I was the Principal Investigator and main author of the U.S. DOE Aquatic Species Program (ASP) Close-Out Report [RR: You can download this 328 page PDF, which I have actually read, here], and thus am rather familiar with it. The report was published by NREL with their own introduction that paints a perhaps somewhat too-positive picture in light of the actual data and results. Thus it should be used with some caution. This report was meant to just summarize the work done by the ASP, which spent about $100 million, (in today's dollars) over about a decade and a half.
8. Microalgae biofuels generally, and algae biodiesel production specifically, is still a long-term R&D goal (likely about 10 years), that will require at least as much funding as the ASP, if not more, and success is, as for any R&D effort, rather uncertain.
9. Some near term applications can be considered, in wastewater treatment specifically (but, wait, do not rush to your nearest algae wastewater treatment ponds - there are thousands of these around, but they are mostly very small and their algae have little or no oil, at least the way that we operate those systems at present. Making oil from algae grown on wastewaters also still requires significant R&D).
10. There are now scores of venture-financed companies, university research groups, government labs, garage start-ups, GFT licensees, web sites, and on and on claiming that they have, can, may and/or will produce algae biodiesel, at low cost, high productivity, soon, etc. None are based on data, experience, reality or even a correct reading of the literature.
11. I am not aware of any work in this field done by Prof. Briggs at U. New Hampshire, outside from an old website that quotes the Aquatic Species Program Close Out Report. There is no basis for the projections he makes for very high biodiesel production rates.
12. Even if R&D proves successful and we can actually produce algae biofuels (maybe even biodiesel) economically (whatever the economics may be a decade or so from now), even then, I am sorry to say that due to resource (land, water, etc.) limitations, algae will not replace all our (or their) oil wells, cannot solve our entire global warming problem, or make me rich quick, at least not honestly. But maybe this technology could be developed in the next few years so that in the future it can make a contribution to our energy supplies, our environment and human welfare.
We will in the future need all such technologies and must in the present study and develop all those that appear at least on their face plausible. But we also must reject those, as in the present case, that are based on absurd claims (such as in this case of productivity) and bizarre contraptions (e.g. closed photobioreactors).
There are no silver bullets, no winner-take-all technologies, no technological fixes, the solution to our energy and environment crisis can only come from, in order, 'demand' management, efficiency improvements, and new energy supplies, to which, maybe, algae processes can contribute.
I hope that this posting helps persuade GFT, and all others in this "business", to CEASE AND DESIST from the absurd and totally bizarre claims they are making. PLEASE!!
Cheers.
John R. Benemann, Ph.D.
jbenemann@aol.com
American Scientist Article Excerpt
The full article is:
The excerpt to which Dr. Benemann referred:
The people now working on these and several similar commercial ventures are clearly eager to make growing algae a going business in this country. Yet it's not hard to find experts who view such prospects as dim indeed. John R. Benemann, a private consultant in Walnut Creek, California, manages the International Network on Biofixation of CO2 and Greenhouse Gas Abatement with Microalgae for the International Energy Agency. He helped author the final report of the Aquatic Species Program and has decades of experience in this field. "Growing algae is cheap," he says, but "certainly not as cheap as growing palm oil." And he is particularly skeptical about attempts to make algal production more economical by using enclosed bioreactors (rather than open ponds, as were used for the Aquatic Species Program). He points out that Japan spent hundreds of millions of dollars on such research, which never went anywhere. Asked to comment about why there is so much effort in that direction now, he responds, "It's bizarre; it's totally absurd."
Canola/Flax intercropped on summerfallow cultivated with electric farm equipment powered by hydroelectric for biodiesel. No nitrogen fertilizer required and Carrots love Tomatoes, Roses love Garlic and pests hate flax. Intercropping for food production is difficult, intercropping for fuel has potential to lower pesticide usage. Fallow with renewable electricity rather than NH3/urea from NG lowers fossil fuel usage in oilseed production. It looks like there is some research in linseed oil biodiesel.
Algae needs a lot more R&D and another decade of work and we should be concentrating on implementing lower fossil fuel farming methods and how to grow proven crops for diesel fuel without the high fertilizer, pesticide and diesel input.
I'm curious about your statement: "No nitrogen fertilizer required."
Could you explain, please?
That statement isn't exact, because whether it's stubble or summerfallow seeding, a starter blend is usually added with the seed (i.e. 11-55-00 ammonium phosphate) plus traces, but the bulk of additional nitrogen fertilizer can be eliminated on fallow land.
In a dark brown/black soil zone in Canada, like where our farm is and a lot of Canola is grown, generally you can grow an equivalent crop of cereal or oilseed on land that was fallowed the previous year compared to continuous cropping with 60-100+ lbs/acre of urea.
Legumes (i.e. soybeans) also don't require additional nitrogen fertilizer. An option to summerfallow in Canada is to rotate a legume like alfalfa.
Corn and feed wheat in continuous cropping low-till methods would be about the highest nitrogen requirement crops.
My dad would fallow about 1/3, but it is rarely done now for several reasons (diesel price, wind erosion, bank taking the farm if every acres isn't seeded, etc). One of the major issues with Canola is disease and although fallow acres are much less than ever, I would think if there is any fallow, more often than not Canola seeded in the next rotation.
Interesting. I'm not familiar with farming practices in that part of the world (you guys are up there!) but you figure you get the equivalent of 60-100+ lbs/acre of urea by leaving land fallow for a year? That's a lot of nitrogen.
Also, AFAIK, N fertilization of soybeans is still frequently recommended but, as you point out -- this may be largely dependent upon your particular crop rotation.
In the past (under hand management of crops) one planted corn and soybeans/pole beans together.
Might be something for the gardners to try.
If winter rains arrive Down Under I'm going to plant a small field of 'Tornado' variety canola on soil prepared with charcoal and small amounts of NPK (urea, phosphate, potash) and dolomite. Wide row spacing should help with bug control using a backpack spray.
However I'm swinging to the view we should use oily weeds for biodiesel, not food crops. Better still go the gasification route which unfortunately is in another league financially.
Robert Rapier: Thanks for that comment. My guess has always been, that this is just hot air.
Thanks for cross-posting this to TOD, RR. Very important, although a bit disappointing (in terms of consequences, not content).
Let me try to put this into perspective:
1st gen biofuels have been basically killed, although some just don't understand it yet. Even part of the MSM admits it these days (corn ethanol, anyone). Sure, 1st gen will get their share of subsidies and the folly will have a short run, but I hope it'll die fairly quickly.
2nd gen cellulosic ethanol is still getting the thumbs up from MSM, although seriously shot down from multiple directions here, in RR's blog
Now, 3rd gen genetically bio-engineered algal biostuff was supposed to save the planet and whatnot. Best scaling, best estimated EROEI and most potential through bio-engineering.
And now? Uh-oh.
I'm starting to get a little dizzy here.
Are there ANY bio-fuels that scale anywhere to useful amounts (1/10 of our current fossil oil consumption) with a worthwhile net energy balance and in economically sustainable way and without depleting soil/sea/ground water/climate?
Or to put it in other words:
Can we please calculate 1st a theoretical thermodynamical process maximum that a bio-fuel production process could achieve, if we could tweak out all the engineering problems.
If this theoretical maximum is worthwhile in terms of:
- CO2/methane/vapor cuts
- net energy balance
- land/logistics/water/solar/raw inputs scaling
- production costs (max 10 x viable current price)
Then a second calculation using an implementation with current known technology (perhaps with a modest 5-15% maximum performance improvement).
Isn't this already done in the initial phase? Isn't it kind of a basic exercise that one needs to do 1st?
THEN and only then should we start to look into implementing, financing, technological breakthrough attemps and theoretical perfectibility.
I think we could have avoided a lot of these follies, if the most knowledgeable people did the calculations first as a two camp battle:
1st camp: prove it that in theory it's worthwhile (with some, perhaps yet unknown, but feasible implementation)
2nd camp: prove it that in theory (using any implementation) it is never worthwhile
Currently it looks to me as without any sound theoretical understanding derived from basic laws of physics, completely silly projects get researched, funded and valuable brain power/time is wasted on things that will never mount up to anything useful (energy-wise).
Or am I completely misreading most of the news about 1st-3rd gen bio-fuel failures?
Frankly, I doubt we'll keep all the cars running, but I would personally bet more on biobutanol from pyrolysis of something like locust trees. At least we know that those technologies work.
I'd bet on locust because they are fast growing and really don't need nitrogen fertilizer. Locust is a legume that fixes its own nitrogen with bacteria. It's also a very dense wood with a high heat content:
"Nine-year-old stands exhibited the highest usable heat content 483.4 MBtu/ha for whole-tree biomass and 432.8 MBtu/ha for woody biomass." DOE Energy Citations Database.
Burying the charcoal would increase the soil quality further and sequester much of the carbon as well.
That wouldn't save our drive-through society, but it might keep some ambulances and motorcycle cops in business.
Locust trees give off toxins that make the leaves hard to breakdown by insects, and I think one of the toxin classes will effect other plants also.
Do you have any links to information on locust toxins? I work with several species, and a couple of genus'of of locust and would be interested.
http://www.vet.purdue.edu/depts/addl/toxic/plant48.htm
As an example. I noticed how earthworms did not do well under the locust trees and the leaves did not break down. Spend 1/2 a day, found enough other data to say to myself 'stop composting these leaves' then moved on.
This is a research center for turning wood to gas http://www.chrisgas.com/
Substitute natural gas yields five times more energy per acre than biodiesel from oil plants http://eescopinions.eesc.europa.eu/eescopiniondocument.aspx?language=sv&... section 4.2.1 in the left margin. The link is unfortunately only in swedish but i guess that it is possible to find the document in other languages because it is written in brussel.
One of the most important parameters must be the energy content so i used the following links and calculated the energy content for different crops.
http://www.vedeldning.com/vedeldning.htm http://www.gde-net.se/files/1/87/88/HX81O95Orr3TtQpLUlafUh496GvEq583.pdf swedish links again but i just can't find the numbers in english.
MWh = Mega Watt hour
8-20 MWh/hectare/year Grain
35-44 MWh/hectare/year Energy forest (fast growing trees (salix in swedish) on farmland)
16-26 MWh/hectare/year Forest (i am not sure if forks are included in the volume)
I appreciate all the good work being done in Sweden on biomass.
People in the US have to do a few obvious things- forget about the present absurd transport system with its reliance on private vehicles of sinfully low efficiency; Then forget about the 10kW per person lifestyle in general; Then put the various energy sources where they fit best- for example, biomass for space heating and CHP.
AND
Remember that there are other thermal power devices than diesel and spark IC engines. Then go look up the NASA space power stirling engines and note how long they last and how efficient they are. And then think of what these things could getting their heat from SOLAR ENERGY instead of isotopes.
But, truth to tell, almost no hope here (USA), Maybe Sweden???
I changed language=sv to language=en and it worked fine.
Try
http://eescopinions.eesc.europa.eu/eescopiniondocument.aspx?language=en&...
Very good! I especially like the obvious recommendation that biomass be used for heating, releasing FF for vehicles, instead of wasting time money and energy trying to turn biomass into liquids for vehicles.
This seems SO OBVIOUS that I keep wondering why people on TOD keep talking about all the hocus-pucus of biomass-to- liquids.
So, please tell me why I am wrong about this, ok? If you do, I promise to shut up about it.
Biobutanol is already available at a "barge" (bulk) price of around $3.70 a gallon according to David Ramey's site.
http://www.butanol.com
Gasoline is already above $3.00 and apparently headed for four by peak summer, so assuming it is possible to scale up production with some government sponsored "heavy lifting" (very doubtful!) to convert ethanol production plants it would be sensible to simply load up right now and just go as is. Once gasoline hits four, butanol is a deal, n'est ce pas?
Yes I know it ain't that simple, but I'm waiting to see who pops the balloon now that I've let it fly.
I already chowed down on the 14,000 gallon annual oil consumption figures of the island nation of Saint Vincent and the Grenadines. It would seem to me that an operation capable of producing that much is a no brainer.
For St. Vincent it would be a lifesaver as gasoline is currently NINE dollars a gallon right now.
Straight butanol at the 55 gallon drum price of $6.80 would be a frigging bargain.
I wrote to Ramey about the idea but he hasn't responded.
I'd LOVE to see him guest post here as I think butanol might have real shot...MIGHT being my hope that "other factors" don't step in with the intention of "stepping ON".
Biobutanol is already available at a "barge" (bulk) price of around $3.70 a gallon according to David Ramey's site.
I doubt that this can be bio-butanol, for reasons I will get into in an upcoming post. Probably conventional petrochemical butanol; the kind I used to make.
Mr. Rapier I am thinking it would be great to get Mr. Ramey in on TOD in some capacity for your upcoming article. I don't know about the others but I'd be thrilled to get his input and your assessment of same.
Currently it looks to me as without any sound theoretical understanding derived from basic laws of physics, completely silly projects get researched, funded and valuable brain power/time is wasted on things that will never mount up to anything useful (energy-wise).
[sarcasm, but frighteningly familiar]
Oh you silly doomers going on and on about laws of physics!
Why do you put down the triumphant power of capitalism? I bet it's because you're really nasty control-freak communists inside, isn't it!
[/sarcasm]
When people actually do those computations, based on sound theoretical understanding derived from basic laws of physics, it seems to me that so far they nearly always point to the same, unpleasant answer:
It's conservation and nukes. We might get lucky, but everything else is probably just noise.
And for the love of humanity, no coal nowhere!
Uh oh.
Your perspective leaves much to be desired.
1st gen biofuels are doing just fine.
2nd gen biofuels i.e. cellulosic production paths are well underway.
3rd gen biofuels or XTL biomass->liquid processes are also well underway.
4th gen biofuels i.e. algal and genetic cocktails are -for the moment- research projects.
What everyone fails to recognize of course, is that the production paths of all the above just so happen to compliment each other. Algae biodiesel for instance, would find a ready and inexpensive CO2 feedstock source from corn ethanol fermentation while the exothermic reaction of XTL processes could provide heat for both.
Here's one of the world's first: http://www.dedini.com.br/realese/231006.doc
No, corn ethanol by itself is not going replace 10% of FF usage, however, corn ethanol facilities are the strategic lily pads for the future mass production of renewable LTFs (1st, 2nd, 3rd & 4th gen) under the integrated biorefinery construct as supported by the DOE.
Biofuels are not a failure - far from it.
Oh and BTW, Dedini announced today that they have succeeded in producing cellulosic ethanol from sugar cane bagasse for $1/gallon: http://biopact.com/2007/05/dedini-achieves-breakthrough-cellulosic.html
Syntec, I really appreciate you posting here, esp. considering the amount of pessimism often encountered.
However, I don't think your post addresses the crux of my post.
- Are thermodynamic ceilings calculated for various processes?
- Where are we know with current implementation tech (scaling/EROEI/true non-subsidized price)?
- How much is there room for improvement (feasibile)?
Personally I do not give a lot of value to pure economic feasibility studies (production price, investment ROI).
Why?
Way too many externalities & direct subsidies clouding the true resource/energy utilisation of the process.
A process that takes more fossil fuels as inputs (in kJ) and produces energy of lesser quality (lower density) and less in volume (liters) can be made look "profitable" or "cheap", when in fact it is a completely wasteful and stupid process.
At the very minimum the process must be analyzed for (energy quantity x energy quality) input/output. I haven't really seen analyses like these for bio-fuels processes, by the startups themselves.
Again, I'm by no means even a beginner on these issues, but a mere man-of-the-street.
However, having also lived through the period of two other tech-bubbles (biotech and Internet) I know that a lot of useless/scam projects get funded that have absolutely no basis in reality.
And I know that the majority guys funding the projects do NOT care. I know too many investment bankers to know better.
All they care about is their exit strategy with nice profits. The project can go down in flames after they exit for all they care.
So, I hope you forgive me, if I'm unfairly over-generalizingly skeptical on bio-fuels, esp. with all the data that RR keeps posting.
I see your side of the argument and I agree with you that there are those who will undoubtedly try to 'make a buck as it were'. Such is the nature of capitalism.
That said, funding for any biofuel project must run the wallstreet gamut until such time as a national directive (not long now) is undertaken to address Peak Oil for Peak as you know, portends a liquid transportation fuels crisis; the key component of which is petroleum exposure not fossil fuel exposure per se.
As such, the PIR or Petroleum Input Ratio of any proposed liquid fuel alternative is of paramount importance.
I fully support conservation, rail electrification, carbon taxes, BPHEVs and all the other mitigation wedges, however, as I recently pointed out to an ASPO colleague - North America is not Europe ergo no matter how many wedges we choose to deploy, a mass produced, renewable liquid transportation fuel(s) will be necessary.
Thanks for posting this!
the real problem seems to be our obsession with the internal combustion gasoline and diesel powered vehicle for personal transportation needs. Its not supportable with anything but unlimited fossil fuels and a perfect solution for CO2 emmissions. If one definition of insnity is doing the same thing expecting different results, then the human culture of the early 21st century is certifiable. Relying on pond scum is like relying on god for gasoline.
I think we might still look to internal combustion engines as part of the long term solution in a drive system such as a plug-in hybrid, as long we dramatically lighten vehicles and do not rely on the liquid fuels to provide energy into the system. The actual energy input would come from fission and renewable sources, if they can scale. We have a lot of potential sources of liquid fuel as long as we do not count on them for energy and as long as we realize that we are not going to have the volume of such fuels that we have now. The ICE's role in this solution would just be to lengthen the range of vehicles if we cannot develop battery technology that does not require it.
Oilmanbob,
I'm with you on this!
We have inefficient car engines moving people inefficiently one or two at a time because oil has been absurdly cheap. The result is enormous consumption of oil on a daily basis. So now that oil is getting scrace we look for some other source of liquid to put in the tank.
This is dumb. Fix the inefficiencies first. Then look for a substitute liquid for the magical black stuff. Maybe we wouldn't need so much replacement volume if we reduced our consumption of oil in the first place.
I agree - internal combustion is too inefficient to survive, plus it needs very pure fuels, but we still need liquid fuels for convenience. Glossing over the technical hurdles, I would put my faith in simple closed algal reactors producing methanol (or ethanol) by metabolism from water, CO2 and sunlight, concentrated to a degree by some simple, solar-driven process, and used in robust alcohol fuel cells that could handle a relatively impure fuel. Thermodynamically it's not unreasonable: say an incident energy of 10kWh per sq m per day and 1% efficiency, that's about 3 litres per day from an area the size of a tennis court. And suddenly sub-Safaran Africa has the resource we need.
Mission: improve the soil
Oh, well, so much for that pie-in-the-sky solution.
Now that it appears that we won't be solving our energy problems with algae, perhaps somebody could do a good article on biodiesel from the jatropha plant. It's a technology that occasionally gets mentioned in the press, but very little info about it seems to be available. Is anybody actually doing this successfully? Ethanol from sugarcane (in Brazil) gets a lot of press, but wouldn't jatropha be somewhat better (since biodiesel has a higher energy value than ethanol).
Wikipedia has a brief entry about jatropha:
http://en.wikipedia.org/wiki/Jatropha
And I don't know much more about it than that. Since it is a subtropical or tropical plant, I guess Iowa corn farmers won't be growing it (therefore, no subsidies from Washington). Maybe that's why we never hear anything about it.
cheers,
Robert
There was something in the news recently about this - my recollection is that people are just starting to think about growing the stuff on purpose, and there is a learning curve involved for figuring out the best way to do it.
Not sure - I think these are the links:
http://www.theoildrum.com/node/2526/187605
http://www.theoildrum.com/node/2524/187424
http://www.csmonitor.com/2007/0508/p01s03-wosc.html
First, I have challenged the oil-from-algae community to support a fair-contest technology demonstration prize, so as to cut through the "bizarre" and "absurd" claims:
The O-Prize.
http://www.geocities.com/jim_bowery/oprize.html
Please read it and consider suggesting it to agencies such as the X-Prize Foundation, the Gates Foundation and, if any government can be made to act responsibly, via some governmental support. The prize is structured such that no philanthropic/government monies invested would be wasted.
Second, Dr. Benemann seems to ignore NREL's claim that open ponds are _not_ viable due to low temperatures during substantial amounts of the year even in the desert areas. This, more than anything else, renders high production rates unachievable. Quoting from the report:
Moreover, high productivities have never been achieved with algae without the use of raceway ponds -- which adds further to the cost-basis of oil from algae rendering it more uneconomic.
As a consequence of these realities, combined with the problem of evaporative loss, I abandoned the idea that one could economically produce oil from algae in the absence of synergistic use of the infrastructure, instead focusing on an economically plausible "biosphere" system that combines several uses and have done the preliminary pro forma net present value calculation which results in a system that produces the following annual revenue streams:
$150M for live fish
$ 70M for biodiesel
$ 50M for fresh water
$ 25M for electricity
$ 8M for salt
$303M TOTAL REVENUE
The calculations are available at:
http://www.geocities.com/jim_bowery/sutabs.html
using the online units calculator Unicalc Live available at:
http://www.calchemy.com/uclive.htm
Hi James,
Glad to see you posting here, I stumbled across your page the other day while researching solar updraft towers and was quite encouraged by your analysis. I posted a similar comment as yours on the first algae article posted here but it got little response. For those who don't know, James was the developer of one of the first multiplayer computer games called Spasim (space simulation): http://en.wikipedia.org/wiki/Spasim.
I would be interested in your thoughts on a couple of points: First, one of the more common criticisms of renewable energy systems is that the energy embodied in their construction and maintenance can only be supplied by our current fossil fueled infrastructure, for example you can't build windmills with wind power alone, etc. I think the solar updraft algae bioreactor has the potential to produce enough energy, both in the form of electricity and biodiesel, to supply the capital plant needed to build another tower, which then could be used to build another, and so on. I would be interested to know if you think that idea pencils out.
Second, I was fascinated to learn that in your second release of Spasim you incorporated the differential equations used in the world simulations that were published as 'Limits to Growth'. I think a compelling world simulation presented as a game-like experience would be an invaluable tool as our various resource, population and pollution crises unfold, have you done any further work along those lines? Would you be interested in contributing to such a project?
Cheers,
Jerry
To first order, the question of energy use for energy infrastructure production relates to the grade of energy used in construction. Since the algae biosphere updraft system produces substantial portions of its revenue from high grade forms such as electricity and biodiesel, it is a reasonable surmise that it is energetically self-constructing.
I take it that by 'grade of energy' you mean Energy Returned on Energy Invested (ERoEI). My understanding is that the basis for the criticism against most renewable energy systems is that the energy required for their construction and maintenance (embodied energy) is not returned over the lifetime of the plant resulting in a net energy loss, or perhaps break-even at best. Of course, such an accounting is largely dependent on how much of the so-called 'lifecycle' of the plant is included in the calculation, for example the energy used mining and processing raw materials, the energy embodied in the fabrication and construction equipment, the transportation infrastructure, etc. This is further complicated by the introduction of biomass into the equation which, as you already know, requires an ecological accounting of water, nutrients, etc.
I think an analysis of the embodied energy and ERoEI of the solar updraft algae biosphere concept would be extremely useful going forward, unfortunately such a task is somewhat beyond my expertise.
Cheers,
Jerry
I guess if I were going to describe what I mean by "grade of energy" it would be dimensions of temperature*power.
Assuming construction using local materials like desert sand, the biggest energy cost of a solar updraft tower is the melting temperature and energy during manufacture of the greenhouse glass.
Using 4mm thickness and a density of 2600kg/m^3 with energy requirement of 3*2.3Mbtu per ton of glass melted,
http://uk.shopping.com/xDN-garden--greenhouses_and_storage_sheds-greenho...
http://www.ca.sandia.gov/crf/research/combustionProcesses/indProc/glassM...
http://www.allmeasures.com/Formulae/static/materials/15/density.htm
and figures from my proforma of 1963.49 hectares per tower and 100MW the energy payback time for the highest energy component of the system construction is:
2.3Mbtu*3/ton;4mm;2600kg/m^3;1963.49 hectares;100MW?years
= 0.519621 years
or one half year's production of just the electrical output (not counting the biodiesel output). Of course there are other components which will add to the number of years for total energetic self-replication but the payback time seems very good.
Moreover, there is some prior work on this topic:
http://www.sbp.de/de/html/contact/download/The_Solar_Updraft.pdf
On the virtual reality front:
We are now seeing the emergence, with systems like Second Life and others, of virtual worlds where simulation-as-pedagogy can take on a dramatically enhanced role in people's lives -- so yes I see the potential of