Re: Refuting The Dimitrov Case Study - Algae
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Re: Refuting The Dimitrov Case Study - Algae         

Group: alt.philosophy · Group Profile
Author: Bob Eld
Date: Jun 28, 2008 15:27

"The Trucker" verizon.net> wrote in message
news:pan.2008.06.28.20.39.03.808648@verizon.net...
> I was recently presented with a supposed "scientific paper" that was
> meant to prove that algae based biofuels were unscientific hokum and
> snake oil. I was, to say the least, rather upset when I read this paper.
> I am not a scientist and all the stuff about PAR's and joules and the
> like was really confusing. But I think I managed to deal with all of
> that and still find the false framing.
>
> http://www.nanostring.net/Algae/CaseStudy.pdf
>
> In the "study" we find the following pronouncement:
>
> E is the Energy in the biomass
> PAR is the energy from the sun
> Q is the efficiencey of the conversion of sun energy to biomass energy
>
> W = PAR * Q
>
> All of this is well and good and reasonable. And then we have:
>
> Photosynthetic organisms use 8 photons to capture one molecule of CO2
> carbohydrate (CH2O). Given that one mole of CH2O has a heating value of
> 486kJ (486 kilo jules) and that the mean energy of a mole of PAR photons
> is 217.4kJ then the maximum theoretical conversion efficiency of PAR
> energy into CH2O is:
>
> 468kJ/(8 * 217.4kJ) = 27%%
>
> Well!!! GIVEN that the moon is made of green cheese and Pinocchio Bush
> tells the truth then the economy is sound and stabilizing. This dude is
> hoisting himself over a fence by grabbing his own underwear. I could not
> find any credible source for these "givens".
>
> But I will leave that aside for sake of argument and just "give" him his
> "givens".
>
> I am going to guess at this because that is what I do. I am not a
> scientist. I am a poker player.
>
> What is missing from this frame job is that great and wonderful
> realization in economics of the "unseen". Yes, we can "see" that these
> photons were absorbed by the algae as the algae made these CH2O things.
> But what happened to the rest of the energy? Did George Bush spend it on
> imperialism? Did those thieving Democrats use it to bribe the welfare
> bums?
>
> The envelope please:
>
> It says here that the rest of the energy bounced off or passed through
> this particular algae or this square micrometer of algae or this bag full
> of algae and it is still available. It did not run away and join the
> circus. It is still available to be used by a different algae.
> That's right! 73%% of the energy is still hopping around in the immediate
> vicinity and available to be used by another fuel producing algae. And
> if we can just manage to get this algae into the vicinity of this
> available energy then it too will suck up 27%% of what is left on the way
> to being 10%% efficient in making some fuel.
>
> Later in the document he uses the 27%% to produce the 10%% because we all
> know that the algae are going to use some of the energy (some of the 27%%)
> for reproduction and respiration. But the problem will inevitably trace
> back to the 27%% false framing and the assumption that the rest of the
> energy just disappeared.
>
> Still later in the document he speaks of the patent awarded GreenFuels
> for a system that seems to do the conversion at more than 40%% (of the
> 10%% or the 27%% or whatever) and accuses the patent office of malfeasance.
> The truth is that bio-reactors _USE_ that reflected/passed through energy
> that was not used by the first plane of algae. Even in a pond the second
> plane of algae will use the energy that passed through the first plane.
> Most of the energy is actually reflected and that is how we are able to
> _see_ the pond scum.
>
> It seems a good probability that this guy's last job was as a consulting
> scientist to a tobacco company. He has now been hired by the league of
> oil and nuclear fascists to fight the competitive free market algae
> farming economy.
>
> --
> "I know no safe depository of the ultimate powers
> of society but the people themselves; and
> if we think them not enlightened enough to
> exercise their control with a wholesome
> discretion, the remedy is not to take it from
> them, but to inform their discretion by
> education." - Thomas Jefferson
> http://GreaterVoice.org/extend

That's not the way I read it. The PAR is the energy (power) of the sunlight
available for photosynthesis. According to this paper, that's about 100
watts per square meter, peak I guess? The typical mid latitude insolation is
a 1000Watts per square meter. peak power total of all wavelength. The PAR is
only the wavelengths photo active in plants, mostly red. Therefore the PAR
in percentage must be 100 out of 1000 or about 10%% of the total.

Now, according to this paper, the photosynthesis efficiency is about 27%%
based on the photon-carbon dioxide analysis that you mentioned. But, that's
27%% of the PAR not 27%% of the total light. Therefore the overall efficiency
must be about 2.7%%

Now I appreciate that the paper is not peer reviewed and we haven't seen any
scientific discussion of this, we are taking the authors word for it.
Furthermore, there is confusion in the paper between energy and power, a
fault NO serious scientist should make, but I think the basic premise is
correct.

Typical insolation in the mid latitudes is about 5 kWHr per sq meter per
day. That equals about 7.3 million kWHr per acre per year. Now, if the oil
has an energy content of 40kWHr per gallon, the absolute maximum gallonage
at 100%% efficiency equals 183,000 gallons of oil. If the photosynthesis is
2.7%% efficient, the gallons produced is 4927 Gallons of oil. That's where
the 5,000 number comes from.

I have no reason to doubt this, it sounds reasonable to me. The question is,
can this number be improved on? I think it can and have written on that.
There are two approaches, one broadens the active PAR to include more
wavelengths and the other shifts unused wave lengths into the PAR region.
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