Is it fodder beet?

[Will Wilson]

Can someone help clear this up for me please.

I always understood that beet used in AD was not fodder beet as this has to low a DM. The beet that should be used in AD was sugar or energy beet.

From memory there was quite a significant difference in gas yield - or am I wrong?

FYI I know more than is healthy about storing just not enough about the actual product.

Will

 

[sjt01]

We used to use fodder beet but changed to energy beet because of the DM issues. Energy yield per tonne DM should be near identical.

Stephen

 

[thesilentone]

The political name is Energy Beet, the reality is it's Sugar Beet...............

Around 370 Nm3 - CH4/ton/VS

 

[Will Wilson]

Thanks for the replies, I knew I wasn't going mad.

So will someone tell the seed merchants pushing 'fodder beet'?

Will

 

[sjt01]

I gather the difference between energy beet and sugar beet is high amino N values, which interfere with sugar extraction.
Stephen

 

[Wilberforce]

Hello, Will hope your well etc. Energy beet is just a way of rehashing failed beet varietys by putting the word energy in front of them! Salesmans dream. Squats down to put tin hat on!

 

[Digester Man]

The political name is Energy Beet, the reality is it's Sugar Beet...............

Around 370 Nm3 - CH4/ton/VS

How successful is the ensiling of beet? I was told 30% of the biogas value runs out in effluent, so its important to capture and use this. This sounds a bit complicated in terms of daily feeding? Also, I was told that ensiled beet went like rubber and was harder to chop. Last question, I assume it is washed before ensiling?

 

[thesilentone]

I hope this helps.

Washing is a simple question of cost, to wash you require lots of equipment, water and it slows down the ensiling. In addition you have lots of waste to handle at the same time.

The alternative is not to wash, this means however, you will need to open the Digester every couple of years to clean the tanks out.

So, cost of washing v cost of cleaning out the tanks (loss of production etc), it appears not to wash is the cheaper option.

You do not have to clamp, you can also lagoon store, you then have the set-up, equipment costs for this alternative.

So, let us assume you decide to clamp without washing, as seen on the pictures above, the beet is still dirty, however not so difficult to chop. It has settled and lost up to 40% of the volume as liquid. This should be caught and stored in a tank, then fed into the AD process.
The ph level needs monitored and the beet fed when appropriate through a cleaner/shredder piece of kit (like the one in the photo, I am sure their are many others)

This looks like a low cost compromise, if your tonnage is not to high, however it is slow.

Beet can be clamped successfully, but great care must be taken when sealing the side of the clamp.

 

[Will Wilson]

The Silent one is bang on the money from what I have learned - We have some research on this (mostly in Germany). The general theme from the German AD is- feed fresh lifting ad lib when needed and leave the beet in the ground for as long as possible Oct -April (April = when the temp increased) and chopped into the digester to a pieces no bigger that an 10p then ensile what you can for the summer.

This only worked well if you owned the land and the harvester as you could tie the field up for longer as you gradually lifted the whole area to feed fresh.

To ensile beet needs to be piled over 6m high (9m is better) in the clamps with conveyors. 10-40% fresh weight loss in effluent over the first few months (FYI the effluent contains ethanol amongst other things and will strip concrete and asphalt) it will knock over conventional clamp walls- It's fairly potent for the plant so worth feeding but it needs very robust drainage for handling /storage

Beet should be covered with silage sheets when the clamps are full (we sell extra tough sheets which work well) the sheets need to be adjusted every other day as the pile sinks to about 1/2 its height over the course of the first few months. The sheets should be small enough sizes that they can be hand balled onto the piles as you cannot drive machinery on the beet.

The beet is probably best stored unwashed, though run over a destoner several times (they used static Grimme machines), and there are additives that can be thrown in to aid the ensiling. Chop the beet into the AD plant with a bucket or the Grimme machine- without wet washing .

Because they didn't wash the beet they would only take beet from ground that was suitable (ie no stones, no clay, dry conditions). They even bought excess beet off the German equivalent of British Sugar, though soon stopped as they could not trust it enough to not contain stones which were a big problem.

On balance the operators after several years nearly all said it was tough to justify the hassle using ensiled beet, operators hated covering it (broken ankles) , the leachate damaged clamps and surprisingly they all said that the key to the success of their plant was keeping it low hassle and employing as few people as possible, beet was neither - I think this is a mind-set we will understand after 5 years of operating AD plants in the UK.

FYI most silage clamps will not be built to withstand the loading of sugar beet piled into them.

Another option for the brave is to mash the beet into a pulp and store it in a lagoon. That is a whole other chapter.

- to clarify I am only reporting what we have seen, I would be keen to hear other peoples feedback.

I would be happy to share our results and info with anyone interested.

[email protected]

01787220560

 

[thesilentone]

feed fresh lifting ad lib when needed and leave the beet in the ground for as long as possible Oct -April (April = when the temp increased) and chopped into the digester to a pieces no bigger that an 10p

The only problem with this is the ph of the beet when fresh.

 

[sjt01]

The only problem with this is the ph of the beet when fresh.

What pH would you expect from fresh beet? We have no problem feeding fresh beet, lifted on demand. We chop to between walnut and tennis ball size, but our feed loop runs through a macerator. We tend to feed beet to about 1/4 of the total, from October to March. When feeding beet that have been out of the ground for some time, we have problems chopping them, so prefer fresh.
Stephen

 

[thesilentone]

Fresh beet is around 2.5 to 3.5ph the AD system operates at 6.6 - 8.5ph. By storing in a clamp the ph of the beet increases, it is a simple test to check when ph levels are ready for feeding.

I hope KWS don't mind me attaching this document, if they do I will remove it. See page 25 onwards.

 

[sjt01]

Fresh beet is around 2.5 to 3.5ph the AD system operates at 6.6 - 8.5ph

We feed fresh beet, maize silage at around pH 3.5 as well as slurry and whey. Normal operating pH is around 7.3. So much is going on with the digestion that the feedstock pH does not have much effect. Its more the balance between acetogenesis and methanogenesis that affects pH. If acetogenesis gets ahead, pH drops, and if you are not too careful the methanogens get inhibited or even killed, resulting in no methane production.

Had a couple of methane crashes, it now seems that lack of trace elements might have been the cause, rather than feedstock.

Stephen

 

[Digester Man]

Grass silage is often 3.5ph if you use an additive and that's making up the bulk of our feedstock. The ph in my plant is around 8 and has always been a bit on the high side

Ensiled beet sounds like a drama that I can do without! Thanks for the insight in the above posts

 

[Will Wilson]

It's topics like this that emphasise the benefit of the Forum - A knighthood for all involved.

If I can help with any more of my limited knowledge let me know. We also work with storing sugar beet pulp which is another essay.

Will

[email protected]
www.bock-uk.com
01787220560

 

[cozzie]

does storage of whole beets in pits not lead to serious mycotoxins and also allot of rotten beet?

 

[Will Wilson]

It shouldn't as long as they are piled very high when the clamps are filled and then stored under plastic silage sheets. They should self compact and effectively pickle.

You must be sure of the type of beet you are using and its dry matter content (I don't know enough about this).

I am not sure about benefits of feeding to cattle - this would be interesting to know.

Will

 

[thesilentone]

does storage of whole beets in pits not lead to serious mycotoxins and also allot of rotten beet?

As regards rotten beet, the answer is no. It is amazing how much compaction occurs through settlement alone (and the leaking of liquids). This combined to very complete and accurate sheeting and sealing of clamp walls and face keeps losses to a minimum.

As regards mycotoxins, I think they may exist, however I am not qualified to give a definitive answer. But, I am aware of good research on pathogen kill in the AD process, which if are a concern I could dig out.

 

[thesilentone]

We feed fresh beet, maize silage at around pH 3.5 as well as slurry and whey. Normal operating pH is around 7.3. So much is going on with the digestion that the feedstock pH does not have much effect. Its more the balance between acetogenesis and methanogenesis that affects pH. If acetogenesis gets ahead, pH drops, and if you are not too careful the methanogens get inhibited or even killed, resulting in no methane production.

Had a couple of methane crashes, it now seems that lack of trace elements might have been the cause, rather than feedstock.

Stephen

Stephen,

Thanks for the info, based on your feed-stocks, I would call your plant 'low risk ' due to the feed stock mix and bacteria development.

However it interests me, and I would be interested to know 1) Operating temperature 2) retention period, 3) Organic loading rate. 4) Plant capacity (feed-stock tonnages and output)

once I have received it, I will give you my suggestions for the same thing FOC

 

[sjt01]

However it interests me, and I would be interested to know 1) Operating temperature 2) retention period, 3) Organic loading rate. 4) Plant capacity (feed-stock tonnages and output)

1. Operating temperature now 39°C, used to be 42°C
2. Retention period 50 days
3. Organic loading rate not calculated. Feeding is determined by gas production, with a relatively rapid response to increased or reduced feeding - a couple of hours.
4. Plant capacity: Total digester volume 800 m3, working volume 710 m3.
Annual feed about 1300 tonnes dairy slurry and straw, 2200 tonnes maize silage, 900 tonnes energy beet, 200 tonnes whey, 60 tonnes farmyard manure.
Daily feed strategy: All the slurry available, all the whey available, 2.5 tonnes beet in season, some fym if not much slurry, top up to need with maize (clamp for dairy unit, digester uses top, sides and bottom, cows get the best).
CHP capacity 170 kW but export limited to 131 kVA. Output depends on site demand.

We are involved in the Warwick University project, and have our bug DNA analysed weekly. Bacteria and Archaean populations are quite distinct from slurry bugs.

Stephen