[Digestion] ***SPAM*** Re: ***SPAM*** Biomethane from cactus

[Paul Harris]

G'day Rex et al,

Thanks for the detailed information, Rex.

In paragraph 3 I would suggest putting the manure through the digester 
to boost biogas production (unless this results in other challenges that 
outweigh the biogas example).

In paragraph 6 I know the generators are 50% efficient (at rated load?) 
but that means 50% of the gas is "wasted" (less if you can use the heat) 
- note that I am an optimist/engineer by nature. I realise that this 
application may be the "best" application for generating sales, but 
direct use of the gas (for heating/cooking?) may benefit more people 
(How do you define "best", and "efficiency"?). I always regard 
electricity generation as the last option for biogas use, with motors 
for pumps etc just a little better.

I like that you are using multiple Renewable Energies in paragraph 7, 
can you throw in micro-hydro as well sometimes(maybe using water pumped 
from the mines)? I have often said we need a "shotgun" approach to 
energy, AD is not a silver bullet.

Good work Rex, thanks for your contribution to the List and all the best 
for the future!

Happy digesting,

HOOROO
Paul Harris

On 13/03/2021 2:01 am, rex at whitfieldfarm.co.za wrote:
> Dear Paul
>
> It is good to see that you are still very much alive and kicking!
>
> SNIP
> Para 3
> Effectively what we have managed to achieve is to plant these at high
> density to produce in the region of 45 dry tons/ha/year. The plants are
> harvested mechanically, macerated and fed to large, mixed lagoon digesters.
> The digestate is separated into moist solids and liquid digestate. The
> liquid is stored and irrigated to reduce plant heat stress when required.
> Manure is added to the solids and composted. Compost is spread over newly
> harvested fields.
> SNIP
> Para 6
> The main application is for power with the use of 10MW class gas engines
> that have a 50% chemical to electrical energy conversion. They also have
> high volumes of exhaust in the 375oC range. In mining in particular, this
> heat can be used for drying of ore concentrates.
>
> Having said all that, the company ran into difficulties. A colleague and I
> are starting an energy company that will have biomethane as a central
> component. Using a mix of PV, wind, biomethane, synthetic diesel, hydrogen,
> fuel cells, etc, our aim is to help mining companies in particular on their
> drive to carbon neutrality.
>
> I just thought I would let all out there know that there is life yet in the
> AD world and that it can be scaled. I am looking forward to any queries. My
> private email is rex(at)whitfieldfarm(dot)co(dot)za. I will endeavour to
> answer all emails.
>
> Kind regards
> Rex Zietsman