[Gasification] algae as a fuel generator

[ART KRENZEL]

Rex,

I am a small scale guy so when you say use the algae as fuel for a power 
plant, I lose interest quickly.  Part of the problems we have today is 
because of the centralized, big power plant theory.

I advocate simple designs of small scale, distributed, combined heat and 
power designs which are "human scaled".

The open pond concept was fairly well knocked on the head, as you pointed 
out, from the wild strains of algae which contaminate the brew and quickly 
takeover from the preferred species.  The big money is going for bioreactors 
where one can better control the environment for the selected species of 
algae.

It is always good to hear from you Rex.

Art Krenzel


>From: "Zietsman, Rex" <Rex at Process.co.za>
>To: <gasification at listserv.repp.org>
>Subject: [Gasification] algae as a fuel generator
>Date: Mon, 19 Mar 2007 09:12:27 +0200
>
>Art wrote:
>"Peter,
>I like your focus on anaerobic digestion (AD) because it works in all
>sizes, a wide range of feedstocks and scales of production.
>BUT, here is a more symbiotic idea.  Algae can produce between 5000 and
>20000 gallons of bio-oil per acre when optimized.  The algae are between
>30 - 50% lipid oils by weight and the rest of the body is starch.  They
>live on CO2, nutrients from dirty water and use sunlight for
>photosynthesis to produce the plant matter.  Details of the system can
>be located at http://www.oilgae.com/
>Here is the great combination.  An AD produces on the order of 35 - 40%
>CO2 and 60 - 65% methane.  The CO2 is easily removed from the gas and
>could be recycled back to the algae bioreactors as feedstock for the
>photosynthesis. The crude purified methane could be used as compressed
>gas for mobile fuel.
>The oil is removed from the algae via several solvent or centrifugal
>systems already made.  The oil goes to bio-oil collection and the starch
>goes back to the AD system to produce more methane and CO2.
>The only thing missing is sunlight and direct sunlight has 10 times the
>energy per unit area necessary for the photosynthesis.
>This is not perpetual motion but it is an interesting symbiotic
>reaction. It works in small scale as well but suffers from economy of
>scale issues as do most energy processes
>Good luck with that one!
>Art Krenzel"
>
>Art,
>In principle you are right about algae. There are some challenges
>however. The challenge in this case is the type of algae reactor used.
>To get really big installations to produce oil in quantity requires the
>use of open ponds. The difficulty with this is that wild species of
>algae can then enter the pond and before you know it, they have taken
>over. Generally wild species do not have a great oil/lipid content. So,
>to protect the high oil species algae requires a photobioreactor (PBR)
>which bumps up the cost enormously but guarantees that you will get the
>yield. The forerunners of this technology are building their plants next
>to power stations so that they feed the algae with CO2. That speeds up
>the process even more. Algae also has the wonderful benefit of absorbing
>NOx as well. So it is a good thing.
>There is still hope for open ponds. You can harvest open pond or wild
>algae and feed it directly to an AD. That will generate the methane you
>are talking about that can be fed into the power station as fuel.
>Alternatively, you can use the power station off gas to dry the algae.
>The dry algae can then be fed into a coal fired power station to
>displace some of the coal. Some of the offgas heat can be used to keep
>the ponds warm to improve the performance of the algae, particularly in
>winter. So large scale open ponds do have some payback though not to the
>extent of generating a biofuel that can be used by vehicles.
>Rex
>
>
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