Dish Stirling v Bio Diesel; Mechanical Work/Acre-Year

Assuming it can be made to work the yield from algae is claimed to be 30,000 gallons diesel/acre-year. This comes out to be 30 kW/acre
(24/7/52).
This is over 3X the gross income as growing berries so it is probably economical especially considering the quality of the land doesn't matter.
Taken along with the 40% efficiency of a diesel engine, the mechanical work from algae oil is only 12 kW/acre (24/7/52).
Dish Stirling averages over 120 kW/acre mechanical work (24/7/52).
Now, to be sure, no one will deny that liquid fuel is often a convenient way to store and transport energy, but even if the electrical energy storage device, i. e., battery, pumped water, etc., is only 10% efficient, dish Stirling _still_ beats bio diesel in mech. energy/land use.
Bret Cahill
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Dear Bret Cahill:

And starches to make plastics, etc.; proteins for animal feed; it reduces the carbon footprint of the fossil fueled power plant in doing that, by remediating the CO2.
...

...
Which does none of those other things.

Not when you include the other demands that this particular technology can address.
I think it should be required technology on all fossil fueled power plants, that way their "cheap" construction cost is moderated to make renewable energy power plants more attractive. I especially like the 1000 acres or so for the algae farm... from one power plant.
David A. Smith
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Liquid fuel will also always be necessary for commercial aviation. Maybe a super cap/battery would make sense on a heavy lift blimp but Boeing and Airbus would whine forever about powering 500 mph aircraft with 50 ton electric motors. Decades ago the _New Yorker_ ran a piece on a faster lighter than aircraft, the "Deltoid Pumpkin Seed." I've never heard anything since.

The capital cost [carbon footprint] of covering 10X the land area with algae tanks is greater than that of solar thermal.
Biodiesel has the advantage it can be cheaply pumped or hauled long distances but this is wiped out by the fact that solar (PV and thermal) can be micro-distributed.
Finally, in the short as well as long term, the cost of desert land does matter even in Nevada.

. . .
We'll need to divert as much of the bio as possible to chemical feedstocks and aviation so the only action that makes sense is to try to do just about everything else from the grid.
First, let's do what we can do: start electrifying farms and trains.
No likely breakthroughs in technology or science will change the fact that sooner or later tractors will be powered by electric motors, either hybrid, battery, trolly lines or some combination.
Put the #@$%! electric motors in the #@$%! tractors NOW while there's still some copper left.
Locomotives already have the motor. All they need is a wire and a battery and maybe a much smaller engine to get around the switching yard.
Bret Cahill
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There's something wrong with your numbers. Thirty thousand gallons of oil per year per acre would be a little over a million kilowatt hours per year. This would be a rate of 120 kW on a 24/365 basis (total time). You are apparently off by ten times.
Therefore the algae number appears to be the same as stirling mechanical number. The efficiency of a diesel engine is higher than the stirling engine because of the higher operating temperature. This coupled with the storage issues, convenience and so on give an advantage to algae oil over stirling solar collection.
An other issue is the installed cost. Almost assuredly, algae can be installed for less than a dollar a watt or $120,000 per acre whereas the costs of tracking dishes, mirrors and engines of a stirling solar system would be much greater.
Beyond that some algae research is claiming yields as high as 100,000 gal of oil per acre per year. See Valcent Vertigrow Algae Farming. If yields prove to be anywhere near this high, it gives a clear advantage to algal oil over stirling solar.
However, no form of alternative energy should be off of the table. Let them all compete in the arena, we need all of the energy we can get.
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Actually it's off by a factor of 16 but good enough.
The important thing is someone is making these comparisons and someone else is checking the figures.
Bret Cahill
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You're going to grow algae at night?
Solar stirling at night and in bad weather?
I don't think so...
Al G
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Those figures included no light at night.
That's why "24/7/52" was included. It wasn't just peak at noontime.
Bret Cahill
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no, algae needs sunlight, but it's growth cycle is 2x per day or higher, so the fact that it slows down to nothing during the night time is not really a factor.
I think you could also argue that if you're able to produce biodiesel from algae at ridiculous rates per day, you could afford to run diesel-powered lighting at very low cost, increasing the yield even higher.
Another factor to keep in mind is that algae production removes huge amounts of CO2 from the atmosphere at same time.
If the next president of the USA decides to sign the Kyoto Protocol, there's yet another positive cash flow in the form of carbon credits.

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You never even made it to the 2nd Law. That's a clear violation of the 1st law of thermodynamics.
Bret Cahill
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Algae is the fastest growing plant on the planet, and I meant it can reproduce itself 2 x per day in a closed system, that's not breaking any laws of thermodynamics

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