Biogas from lucerne?

[sjt01]

We have just had some clamped lucerne silage analysed, and it comes out at 10.3 ME. Makes me think it would be good for the digester if we can keep the C:N ratio ok.
For us a big advantage is that it grows for 5+ years, only needs a dose of digestate occasionally, disadvantage is that first year yield is low. We would feed it 1/3 lucerne, 2/3 maize.

 

[Paul E]

And therein lies the problem.
Feeds should be fed to livestock - it's unethical to waste it producing gas.
I'll let you have all the sh!t and you can digest that.

 

[sjt01]

And therein lies the problem.
Feeds should be fed to livestock - it's unethical to waste it producing gas.
I'll let you have all the sh!t and you can digest that.

Unfortunately our planning only allows for material from our farm to be digested. About 50% of what goes in is cow slurry, most of the rest is the top, sides and bottom of the maize clamp which is not the same quality as the very best in the middle, which is reserved for the cows. The same would apply to the lucerne. Our crops are primarily grown for the dairy, and the lower quality goes in the digester. We do not discard a single kilo of silage now.

 

[Exfarmer]

And therein lies the problem.
Feeds should be fed to livestock - it's unethical to waste it producing gas.
I'll let you have all the sh!t and you can digest that.

Please be a little more moderate in your comments, you are quite correct in this, but @sjt01 is just responding to the markets, as do most farmers, take decisions based on profitability rather than what may be best for the world.
Stephen has made many valuable contributions to this debate and acknowledges there are conundrums associated with bio gas production.

 

[bez]

Totally agree with the above comments from Exfarmer. If there was a high enough demand for food, no farmers would have looked at AD. sjt01 has diversified into something to try and keep his livestock enterprise profitable. From what little I have picked up he seems to have managed to fit it into compliment his other enterprises.

 

[The Son]

Would the protein content be too high with the lucerne?

 

[sjt01]

Would the protein content be too high with the lucerne?

For pure lucerne feed, the C:N ratio would not suit. I would only feed about 30%
These guys struggled with pure lucerne
Biomass and Bioenergy
journal homepage: www.elsevier.com/locate/biombioe
Anaerobic mono-digestion of lucerne, grass and forbs – Influence of species
and cutting frequency
Radziah Wahid a,b,∗ , Lu Feng a , Wen-Feng Cong c , Alastair James Ward a , Henrik Bjarne Møller a ,
Jørgen Eriksen c

 

[Paul E]

Please be a little more moderate in your comments, you are quite correct in this, but @sjt01 is just responding to the markets, as do most farmers, take decisions based on profitability rather than what may be best for the world.
Stephen has made many valuable contributions to this debate and acknowledges there are conundrums associated with bio gas production.

I'm sorry you feel these comments are immoderate, but in this part of the world we tell it like it is.
You will also note that I didn't criticize sjt01 for fully utilizing "the system" even though putting top quality feeds (I assume everyone here will agree that Lucerne et al are top quality) into AD is, certainly to a livestock farmer on p!55 poor land, sacriledge. I don't venture into this thread often, so I'm sure his input here is greatly appreciated, I merely suggested that it would be better all round, that the Digesters were fed with stuff that had already been digested so that everyone won.

 

[Paul E]

Totally agree with the above comments from Exfarmer. If there was a high enough demand for food, no farmers would have looked at AD. sjt01 has diversified into something to try and keep his livestock enterprise profitable. From what little I have picked up he seems to have managed to fit it into compliment his other enterprises.

I think you've missed a point here.
There is HUGE demand for food, many millions of people around the world are starving, they just don't have the wad to pay for it with.
And all credit to sjt01 , but surely (being blunt here) the digester will be subsidizing the livestock enterprises, (As you word it as "keep") unless he's done something different to make them pay????
Of course, I'm sure someone will tell me I'm wrong, purely because I see things from a different angle.

 

[sjt01]

I think you've missed a point here.
There is HUGE demand for food, many millions of people around the world are starving, they just don't have the wad to pay for it with.
And all credit to sjt01 , but surely (being blunt here) the digester will be subsidizing the livestock enterprises, (As you word it as "keep") unless he's done something different to make them pay????
Of course, I'm sure someone will tell me I'm wrong, purely because I see things from a different angle.

Our lucerne is a crop which we grow for the dairy, it is very low input (one dose of digestate a year), brilliant for soil carbon capture and soil structure, and if we can use the lower quality stuff for the digester that is a bonus. Like you, I am appalled at the crop fed digesters, many of which haul the crop for tens of miles to the digester. They also tend to waste the heat generated by the generating engine. As you can see below, we try to utilise as much as possible, using what is not fit for the dairy cows to feed the digester and utilising all the outputs.
There are plenty of people in many countries including ours without enough food, but the amount we waste would feed them many times over. We need structural reform to sort the pay disparities, and the waste, packaging and haulage costs in the food chain. In the meantime, we are producing low carbon electricity. From how people in UK pay, they are far more concerned about energy than food.

I had hoped this would be a technical thread, but I am happy to defend our way of doing digestion, if not the pure crop fed systems.

 

[thesilentone]

I think you've missed a point here.
There is HUGE demand for food, many millions of people around the world are starving, they just don't have the wad to pay for it with.
And all credit to sjt01 , but surely (being blunt here) the digester will be subsidizing the livestock enterprises, (As you word it as "keep") unless he's done something different to make them pay????
Of course, I'm sure someone will tell me I'm wrong, purely because I see things from a different angle.

The food v fuel debate is worth having, however it must be based on something to give it credibility. The western developed economies waste enough food to feed small Countries mainly driven by supermarket specifications, bogof and best before dates. A small farmer growing energy crop has way more benefits than negatives.

There are now whole regions of Germany (Saxony) that grows very little other than energy crops for AD, however the trade of is the Germans have cancelled all development in Nuclear.

So, what do you want, food of fuel ? Of course the answer is both, however no other form of power generation (base load) provides the environmental benefits that AD does.

 

[Digester Man]

@sjt01 lucerne is a high protein crop and as I am sure you know, protein is converted into ammonia and H2S which can inhibit the process. If you dilute it with enough slurry and maize it might be ok, as with everything in AD it'll take some trial and error to see how it fits into the mix.

Ignore the comments above - its your own land so grow whatever makes gas as cheaply as possible.

 

[sjt01]

@sjt01 lucerne is a high protein crop and as I am sure you know, protein is converted into ammonia and H2S which can inhibit the process. If you dilute it with enough slurry and maize it might be ok, as with everything in AD it'll take some trial and error to see how it fits into the mix.

Ignore the comments above - its your own land so grow whatever makes gas as cheaply as possible.

One of my reasons for wanting to use lucerne is that it is the best crop we have for the soil, developing a fantastic root structure over the 5-6 years it is in the ground, drought resistant and not requiring nitrogen, so brilliant environmentally. I was thinking of an absolute maximum of 30% of energy from lucerne, probably nearer 20%

 

[DaveGrohl]

Are people even bothering to get wound up by this still? As far as I can make out hes a business man trying to earn a living by legal means. Hes not trucking all his feedstock in. Good luck to him.

 

[thesilentone]

When cut the N level of grass and lucerne are similar at around 6.0kg/ton. However once wilted and clamped, these figures change quite dramatically. Grass increases to around 8.5 kg/ton, where lucerne increases to around 12.5 kg/ton which is heading towards the levels of Poultry Manure.