This seems effective and green.

[Harry Bloomfield]

It seems to run 24/7 and has done so far as I know, for at least 2+ years, but what do the experts think?

We are staying just a short walk away from the installation.

[newshound]

Havn't heard anything about the Ambridge one for a while.

[tabbypurr]

Great technology for the 3rd world. China has been issuing grants for small farm installations. The cheapest version of this technology is nothing more than a giant polythene bag plug plastic tube going to a one ring burner.

How it adds up in this country I don't know. There is the potential to dry the slurry then burn it too.

NT

[Harry Bloomfield]

Tim Streater explained on 28/03/2017 :

The slurry seems to be augured into the tank, the gas collected, pressurised, then fed to the generator system. I don't know how much power it actually generates, but the substation and overhead outgoing lines are quite substantial.

My guess as a past observer of the installation, is one of seeing the slurry being brought in on carts, by tractors, obviously from other local farms.

[Tim Streater]

It does however involve the usual FIT theft.

Where does the slurry, "biocrops" etc come from, how far, and what cost is involved in doing that as opposed to doing something else with the slurry etc.

IOW, what are the actual economics when the FIT theft is removed?

[Tim Streater]

250kW.

[Chris Hogg]

AIUI the feed for these small-scale biodigesters is a mix of farmyard slurry, i.e. runny cow shit, and crop residues such as stems, haulms, stubble etc. Under normal circumstances, the slurry would be sprayed back onto the fields, providing a modest amount of 'organic' fertiliser for crops, and the crop waste would either be ploughed back, also to fertilise the soil and improve its structure, or made into silage, hay, straw or even just burnt off in the fields, although I think that last practice is declining and may even be a thing of the past now.

If these biogas generators are going to be widely adopted, then the traditional uses for their feed will have to be replaced by something else. But stuff that would otherwise have just been burnt off, is being usefully used.

and when artificial fertilisers and soil conditioners have to be used in their place?

[harry]

It has been done for decades a sewage works. ISTR there are grants for biogas installations.

They are not very efficient using shit, a lot of CO2 is produced as well as methane.

[Harry Bloomfield]

Tim Streater laid this down on his screen :

So probably not much output for a lot of investment building the facility then? It looks more impressive than its its output.

[alan_m]

If they are not growing their own energy crops on the farm then its probably not that 'green'. I wonder if it is financially viable without a feed in tariff subsidy?

[TimW]

It's a great way to deal with waste, keeping methane out of the atmosphere and recoup a bit of energy. It's a crap way to generate energy.

Energy crops are madness in the uk. They only make sense where you have prairies to spare. Here the more energy crops you grow the more food you have to import, and it is a desperately inefficient way of making energy.

The economics are all about subsidies. Agriculture is subsidised, the crops are moved with subsidised diesel and then the AD produces subsidised gas or electricity through a feed-in tarrif.

There may be reasons to pay for clean waste disposal but AD plants running on crops are just scams really, making money out of mis directed subsidies. A bit like being a benefits scrounger only you wear tweeds and drive a Range Rover.

It will doubtless be worse after brexit.

Tim w

[tabbypurr]

Of the facility I saw there wasn't much to it, just a huge tank plus a CO2 separator.

NT

[Tim Streater]

"Just burnt off" is not actually so daft, which is why forest fires are not always a bad thing. The organic content burns off, but the mineral content does not and is available to be ploughed in. AIUI, that mineral content is then more easily available to new growth than it would be just from stuff rotting down.

[damduck-egg]

Stubble burning has been banned in the UK since 1993 to all intents and purposes.

The runny cow shit can be produced in huge quantities which produces storage problems , it also cannot be spread on the land at certain times in case the nitrates it contains contaminates the water table or watercourses so farmers are prohibited from spreading it for most of the Winter. That exasperates the storage problems so getting rid of it another way can alleviate the problem.

G.Harman

[The Natural Philosopher]

Almost no 'green' solutions are viable without subsidy.

[The Natural Philosopher]

ITYM exacerbates....

[RJH]

It's more about capital costs, which are apparently going down quite quickly (from 2010). What little I know is from this:

And netting everything down is complicated by tax (CCL for example) as well as FIT subsidy. And a load of other stuff, like uses for waste heat.

Seems that it might, suitably scaled, stack up in the not too distant future according to that report.

[RJH]

Table 31 (p.118) of that report I linked to upthread gives some interesting projections (to my untrained eye). And break-even based on a

20% capital return.

Now, if it was state run . . . ;-)

[Chris Hogg]

But the biogas generator won't get rid of the nitrates, which will remain in the digester, and ultimately get spread back on the land, according to the OP's link, so the problem of timing that spreading to prevent nitrates contaminating the water table still exists.

[Chris Hogg]

Which I've just realised answers the question about finding a replacement for the 'organic' fertiliser in farm slurry with an inorganic one. That in fact won't be necessary if the biogas residue is used back on the land.