[Digestion] Negative Biogas Press

Mon Feb 14 06:22:02 CST 2011

We like to point out the studies that show much higher plant uptake of
digestate - with free nitrogen - than the original manure material. New
Danish study should be out soon on total lack of any problem materials
(disease, pathogens) in the digestate.

Randy Mott

CEERES

From: digestion-bounces at lists.bioenergylists.org
[mailto:digestion-bounces at lists.bioenergylists.org] On Behalf Of Duncan
Martin
Sent: Monday, February 14, 2011 12:11 PM
To: For Discussion of Anaerobic Digestion
Subject: Re: [Digestion] Negative Biogas Press

Hi Alex

There's a lot to respond to here - but I suspect a lot of it is nonsense. 

It's true that biogas production removes carbon that could enrich the soil.
However, many (most?) AD feedstocks are unsuitable for direct applcn to the
soil (for a range of reasons), whereas the digestate is beneficial. So
without AD, there could be no enrichment of the soil. With AD, there is
substantial enrichment, even if less than some theoretical (but
unattainable) maximum. 

In the case of a feedstock that can be applied directly, of course, that
should be considered. Animals have been 'manuring' the soil since the dawn
of time, after all.......

Clostridium spp would not be unusual in AD. I have no idea whether the
botulinum toxin is produced in AD. However, I would be surprised if it is
stable once applied to the soil - and a 'rest' period should always be
allowed after spreading digestate. How long depends on the soil and the crop
- longer for salads than for root vegetables or cereals for example.

So any problems of sick cattle might well be caused by poor management: i.e.
allowing grazing too soon after application. There is nothing unusual about
applying digestate to fodder fields: it has been done for almost 100 years
and I have never heard of this problem before.

I don't understand German, so I can't comment on the video clip - but I
wonder if this issue mainly relates to grass-fed AD. This is quite common in
some German-speaking countries, encouraged by generous prices for
electricity from biogas. I wonder if farmers under financial pressure have
been tempted to cut corners?

Duncan Martin PhD

Cloughjordan Ecovillage

Ireland

www.thevillage.ie

On 13 February 2011 23:37, Alexander Eaton <alex at sistemabiobolsa.com> wrote:

Hi All, 

I have received this from a few people now...it is clearly circulating
widely.  I have plenty of comments regarding the soil aspects, and certainly
some of the AD sludge contents from industrial or black water plants is a
bit beyond my expertise, but I would certainly appreciate some comments from
this group, especially any Germans that can comment on the YouTube part.
This guy clearly is now against biogas, and it would make sense to have some
good responses to this type of thing.   

Best

Dear Kamal,
Dear All,

Besides the clear and proven advantages of biogas there are at least two
extremely severe problems:

Organic matter that is converted into gas is no longer availabel to produce
humus, so there are reports from farmers that the soil is getting less and
less producticve. Rich soil may be far more important that the relatively
litte amount of gas. Composting expecially with earthworms and additon of
some charcoal dust (can easily be made from straw, rice husks instead of the
terrible burning) ideally plus stone dust can be far more beneficial with
rising productivity for food and more biomass and is simple, too. At TUHH we
are now working intensely of also composting urine and mixed excreta
stabilised by lactofermenters together with woody wastes to make more soil
as I want to work with ecolocical agriculture and not do industrial
agriculture with addion of fast fertiliser. Biogas can be a threat for long
term food security and you will have to pay for the gas with more and more
fertiliser demand, less water reproduction, flooding through compacting
soils.

In Germany (see    <http://www.youtube.com/watch?v=3cNyyU3zcXY>
http://www.youtube.com/watch?v=3cNyyU3zcXY sorry in German) (and probably
elsewhere)  there are dramatic problems with the masses of heavily
subsidised biogas plants for food to energy producion where Clostridium
botulinum is growing rapidly under anaerobic conditions producing the highly
toxic substance, there are hundreds of farms where all milk cows are dying
and the farmers are ruined, even they became ill sometimes. The reason are
fodder fields that are fertilised with the sludge from the biogas plants.
The very dangerouos botulinum toxin (misused by people who hate aging by
paralysing nerves in the face thus turning it into a mask, then called
botox) is only showing effect after many month so the effect is often not
related to the cause.

I used to be very positive towards biogas and have planned and built them, I
will not do this anymore except for some industrial wastewaters. Maybe also
for sanitation in areas where the soils are super humus rich already and
botulism can be avoided safely.

Kind regards

Ralf

For Discussion of Anaerobic Digestion <digestion at lists.bioenergylists.org>  

-- 
Alexander Eaton
Sistema Biobolsa
IRRI-Mexico
RedBioLAC

Mex cel: (55) 11522786
US cel: 970 275 4505

alex at irrimexico.org
alex at sistemabiobolsa.com

sistemabiobolsa.com
www.irrimexico.org
www.redbiolac.org

_______________________________________________
Digestion mailing list

to Send a Message to the list, use the email address
Digestion at bioenergylists.org

to UNSUBSCRIBE or Change your List Settings use the web page
http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergyli
sts.org

for more information about digestion, see
Beginner's Guide to Biogas
http://www.adelaide.edu.au/biogas/
and the Biogas Wiki http://biogas.wikispaces.com/

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/digestion_lists.bioenergylists.org/attachments/20110214/bad029a7/attachment.html>