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THE Algae Thread pt 3 (merged)

Discussions of conventional and alternative energy production technologies.

Re: THE Algae Thread pt 2 (merged)

Unread postby Carnot » Tue 21 Jul 2015, 09:51:37

PV panels, wind, hydro and wood fired CCG. Possible yes, but at what cost?

Talk is cheap. Now do the economics and the EROEI and net energy gain. Oh, and by the way the circulation has to be maintained in a raceway ponds to avoid settling. A PBR could be drained down to a circulating tank I guess.

Judging by the success to date, and endless claims that have not materialised, I would rather "invest" my money on the horses than algae. At least I would have a chance of making some money.
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Re: THE Algae Thread pt 2 (merged)

Unread postby Graeme » Tue 21 Jul 2015, 15:13:22

We've heard the above misleading rhetoric from algae biofuel bashers before. I can play your game too. I prefer the more credible NREL report.
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Re: THE Algae Thread pt 2 (merged)

Unread postby Carnot » Tue 21 Jul 2015, 15:57:24

I have read it,have you? It does not exactly confirm you polemic belief, far from it. Many challenges ahead or did you not get that far.

By the absence of any cut and paste I guess not. Maybe you did not like the reality.
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Re: THE Algae Thread pt 2 (merged)

Unread postby Graeme » Tue 21 Jul 2015, 16:04:25

I read it. There are challenges, which are being met by the industry and US government-sponsored institutions mentioned above (page 17). As I said before, the NREL are confident that ultimately algae biofuels will prevail:

Clearly, this is beyond the growth rates experienced by the biofuels industry in the past several decades and it would require very concerted effort industry and government to achieve by 2030. Beyond this timeframe, algal biofuels may make even greater contributions to liquid fuel supply. Certainly the analysis reported here suggests that large scale algal biofuel productions may eventually become economic viable.
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Re: THE Algae Thread pt 2 (merged)

Unread postby Graeme » Wed 22 Jul 2015, 16:00:38

So five years after this report was written, the DOE decide that the algae biofuel industry is worth supporting. That doesn't sound like a dead horse.
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Re: THE Algae Thread pt 2 (merged)

Unread postby ennui2 » Wed 22 Jul 2015, 16:15:04

Graeme wrote:So five years after this report was written, the DOE decide that the algae biofuel industry is worth supporting. That doesn't sound like a dead horse.


They supported corn-based ethanol at one time, did they not? And Solyndria. The Government's judgment is not infallible.
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Re: THE Algae Thread pt 2 (merged)

Unread postby Graeme » Wed 22 Jul 2015, 17:56:15

Irrelevant. Now they are supporting a different industry.
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Re: THE Algae Thread pt 2 (merged)

Unread postby vtsnowedin » Wed 22 Jul 2015, 18:44:22

pstarr wrote:What would sync up?

Just the fact that when the sun is shinning it could both feed photosynthesis in the algae growing in the ponds and run the PV panels needed to run the circulation pumps needed to optimize that reaction. If it's dark out there is no need to run the pumps.
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Re: THE Algae Thread pt 2 (merged)

Unread postby Carnot » Thu 23 Jul 2015, 03:10:56

I think that you will find that their needs to be a minimum velocity to avoid agglomeration of the algae, especially so in raceway ponds and also in PBR. In the latter case it might be possible to drain down to a stirred tank but that might not be a complete answer, as it is likely to leave pools.
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Re: THE Algae Thread pt 2 (merged)

Unread postby isgota » Thu 23 Jul 2015, 05:17:31

Carnot wrote:Isgota has provided an example form Algenol. Algenol have made many claims and have been plying their process for years. I doubt if it can be made to work commercially. But let us examine their claim, provided by the Isgota post, of an ethanol yield of 8000 gallons per acre. As ever the devil is in the detail and misleading units are always used to mask the truth. For simplicity I will use the following conversions:

1 acre as 4000 square metres.

Average PAR lower US 100 watts/square metre (8760 hrs/year) = (8760 x 100 x 3600) = 3.153 GJ per square metre

(For simplicity- I have not calculated photon density or number of photons which is more correct)

PAR source: http://www.atmos.umd.edu/~srb/par/Figure01.htm

8000 UG galls ethanol per acre = 2 US galls per square metre


2 US galls ethanol = 6 kg ethanol

1 kg ethanol = 30 MJ HHV

Energy of Ethanol produced = 180 MJ (6 x 30)

Efficiency on ethanol yield = 180/3153 x 100 = 5.7%

Now for a C3 plant, which algae is, to produce a 5.7 % yield of ethanol (+ other products which are required by the algae cell) this would be exceptional
(some might say impossible, which is where I sit).


There is a discrepancy with that efficiency number and the number stated in this paper:

Algenol aims to produce about 56 000 L of ethanol
per hectare per year using about 430 polyethylene photobioreactors
per hectare, each with about 4500 L of culture
medium containing about 0.5 g/L of cyanobacterial
biomass (10). This production target is within achieved
photosynthetic yields (2-4) and corresponds to 1.8% solar
energy conversion efficiency for average incident sunlight
energy levels in the United States (3).


56,000 L/ha yr equals to about 6000 gallons/acre yr. So rescaling to 8000 gallons/acre yr means about 2.4% of solar conversion, still far away to the 5.7% you estimated.

By the way, that paper includes the LCA study of the Algenol process (well an old PBR design less productive) and it yields positive net energy.

Carnot wrote:Talk is cheap. Now do the economics and the EROEI and net energy gain. Oh, and by the way the circulation has to be maintained in a raceway ponds to avoid settling. A PBR could be drained down to a circulating tank I guess.


The thing is, it doesn't seem to me (from videos and photos I've seen, and articles read) that the Algenol's PBRs are circulating the growth medium, in fact its PBRs work in batch. That could be quite an advantage to minimize energy and OPEX costs.

But again, the big question mark are the CAPEX costs, will be low enough to make algae fuel to a reasonable cost?
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Re: THE Algae Thread pt 2 (merged)

Unread postby Carnot » Thu 23 Jul 2015, 06:00:18

Isgota,

If you go the Algenol website can see their latest claims. Actually they list other liquids along with ethanol (500 gallons ULSD, 380 gallons gasoline and 315 gallons jet). I counted it all as ethanol to make it simply. The liquid hydrocarbon will have an energy value of around 43 MJ/kg which would make the conversion higher in my expample.

What PAR figure did you use? I took the data from the PAR project which for the US gives about 100 w/m2 annual mean average which calculates to the 3.15 GJ per square metre. I am open to persuasion but if we take the annual maximum from the same source it is 140 w/m2 making the insolation 44.15 GJ/m2. That brings the conversion down to 4.07% . Remarkable for a C3 plant. The PAR project source link is in the post. I have not found a better source for PAR insolation and I did look again. I think this source is as good as any.

As I said. I would rather put my money on horses, and this is why Algenol is making slow progress. I have yet to see an economic large scale PBR and probably never will.
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Re: THE Algae Thread pt 2 (merged)

Unread postby SeaGypsy » Thu 23 Jul 2015, 06:48:11

I just did a hack job on the numbers provided & broke them down to each kilo of biomass creating a kilo of oil a week, year round. Obviously an impossibility.
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Re: THE Algae Thread pt 2 (merged)

Unread postby isgota » Thu 23 Jul 2015, 07:47:12

Carnot wrote:What PAR figure did you use? I took the data from the PAR project which for the US gives about 100 w/m2 annual mean average which calculates to the 3.15 GJ per square metre. I am open to persuasion but if we take the annual maximum from the same source it is 140 w/m2 making the insolation 44.15 GJ/m2. That brings the conversion down to 4.07% . Remarkable for a C3 plant. The PAR project source link is in the post. I have not found a better source for PAR insolation and I did look again. I think this source is as good as any.


All right, I think I've figured out why there is a discrepancy. In the paper maybe are talking about total solar radiation, while you are considering photosynthetically active radiation that is just 45% of the total. That way one number is about half of the other.

Still I don't think algenol's numbers are crazy. The absolute limit is 11%, and 5.7% is within the 3 to 6 % level the wikipedia article says.

And actually that number could be based in real productivity results. Some years ago there was a magic number floating around and based in theoretical calculations in algae biofuels, 10,000 gallons/acre yr, and before starting real field production Algenol used it.

But when they started experimenting they discovered their original PBRs weren't stable in production, and they changed the design. This article talks about it.

Now, this no guarantees a commercial system, because you need to build thousands of acres on budget and time, but I don't see any red flags in the PAR efficiencies.
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Re: THE Algae Thread pt 2 (merged)

Unread postby Carnot » Thu 23 Jul 2015, 08:26:12

Isgota,

I am a bit pushed for time. I am afraid I disagree with you. To get 4+% with a C3 plant is beyond the limits of what is credible. i do not think Wikipedia is the most reliable source. I have a paper titled - "What is the maximum efficiency with which photosynthesis can convert solar radiation into biomass" which is from Science Direct and I think is now behind a paywall. I can email it to you if you wish.

This gives a very good view on what is possible. Like anything it is down to opinions. I do not entirely agree with all of the paper but it is fair and reasonable.

In this paper the theoretical maximums are 4.6% and 6 % for C3 and C4 plants respectively. The actual reported efficiencies (real ) are 2.4% and 3.7%

The PAR is generally accepted to be the band of radiation between 400 and 700 nm- this paper says 400-740 nm. It does not make that much difference. The chlorophyll absorbs in two bands at 44-450 nm and around 680nm to initiate the z-scheme in PS2 and PS1. That is the rate limiting step for the production of ATP and NADPH.
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Re: THE Algae Thread pt 2 (merged)

Unread postby isgota » Thu 23 Jul 2015, 08:36:31

Is this one?

Just look at the Figure 2. The basis for that 4.6% in C3 plants is total solar radiation, not PAR.

Algenol claims is at 2.4% (maybe a little more due to the HTL oil by-product). It's within range.
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Re: THE Algae Thread pt 2 (merged)

Unread postby Carnot » Thu 23 Jul 2015, 09:00:33

Isgota. Correct paper. But remember the 2.4 is the maximum achieved. That does not make it achievable 365 days per year.

If Algenol are claiming 2.4% yield on solar PAR then their published yields are wrong,. They cannot have it both ways. If the PAR is 3.15 GJ m2 then the yield will be 2.4% of 3.15 GJ which 75.6 MJ of products - that is about 2.5 kg of ethanol, not 6 Kg.
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Re: THE Algae Thread pt 2 (merged)

Unread postby isgota » Thu 23 Jul 2015, 10:07:35

Carnot,

You're mixing up total solar and PAR efficiencies. That 2.4% is based on total solar. Just multiply by 2 the 3.15 GJ m2 and you will have the total solar (more or less). Well, it's probably a bit more than 2.4% due to the HTL oil.

Carnot wrote:But remember the 2.4 is the maximum achieved. That does not make it achievable 365 days per year.


Actually, the paper says that number is based across a full growing season, so could be an annual measure. But the most important difference is that is based on CO2 concentrations of 380 ppm, this algae culture is CO2 enriched.
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Re: THE Algae Thread pt 2 (merged)

Unread postby isgota » Thu 23 Jul 2015, 10:22:22

SeaGypsy wrote:I just did a hack job on the numbers provided & broke them down to each kilo of biomass creating a kilo of oil a week, year round. Obviously an impossibility.


A kilo of biomass creating a kilo of oil a week, year round? Could you elaborate this, please?
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