[Digestion] Negative Biogas Press

[Duncan Martin]

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 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
>
>
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