Vineyard Farms: Raising A Stink...?

One of the many interesting things I learned from last week’s Medway Council Planning meeting (which deferred a decision upon the Vineyard Farms plans for a luxury country club and restaurant complex on Green Belt land at Upper Bush) was the existence of a proposed “energy centre” as part of the development. Councillor Gary Etheridge mentioned that this would produce 46% of the power requirements of the Vineyard Farms new Xanadu (and asked where the other 54% was coming from…).

One of the many criteria a developer needs to meet in order to justify the rape of green belt land is to demonstrate that their proposals are “low carbon” (whatever that really means) and energy-efficient. Vineyard Farms intend to tick this big green box with their “energy centre”.

Very little detail on how this will work has been provided by them, perhaps on the basis that no-one can object to it if they don’t know anything about it. I had seen references to the production of energy from biogas as the preferred “green energy” source in the Vineyard Farms glossy brochures on the Medway Planning Portal, but I had not paid much attention to any of it as there was so little detail.

In short, it seems that the grape pomice (the stuff left over once all the juice has been squeezed out of the grapes) will be put into an anaerobic digester to make methane, which would then be burnt in a gas-fired generator set to produce power. Although Vineyard Farms haven’t said so, the system in their brochure looks very much like the containerised system provided by Qube Renewables, a 2018 UK biogas start-up that has just sold out to a Singapore-based company (part of the ongoing national asset-stripping process that sees any potentially worthwhile UK company bought up by overseas firms: “taking back control” I think it’s called…).

The Qube bio-energy set-up...

The Qube set-up looks somewhat experimental, comprising of a bunch of shipping containers, flexible hoses and tanks that don’t look very pretty at all and which will presumably be hidden away inside the “energy centre”. There isn’t a lot on-line about Qube Renewables beyond what’s on their web-site and it would be interesting to know if they actually have any working units in the UK.

In terms of the energy claims, the “46%” figure did actually add up when I did some back-of-a-beer-mat calculations. If you assume that the vineyard will be 900 acres and yields 3 tonnes of grapes per acre (typical low-end UK yields according to Mr. Internet), that’s 2700 tonnes of grapes. Pressing takes out 80% of the mass as the juice, the other 20% being pomice, so there will be 540 tonnes of that to feed to the little bugs in the bioreactor. It seems (according to Mr. Internet again) that you get around 150 cubic metres of biogas from a tonne of waste, and a cubic metre of biogas put into a gas-fired generator yields about 2KWh of energy. So if all goes well, the bio-digester should produce 150 x 540 x 2 = 162,000 KWh a year, a figure pretty close to the one Vineyard Farms quote in their glossies (158,000 KWh).

If all goes well…

Even when all is running smoothly, anaerobic digesters produce low levels of hydrogen sulphide, the rotten eggs smell. This has to be removed from the biogas as it is acidic and corrodes the gas combustor. Nevertheless, anaerobic digestion facilities tend to have a permanent whiff about them, something the Riggalls Court residents (and maybe the rest of Cuxton) might just get to find out for themselves.

The bugs in anaerobic digesters are delicate little things that need constant TLC. Feed them something they don’t like, or get the temperature wrong, and they die off. Sometimes the bugs just decide to die out of spite anyway. Anaerobic digestion can be a finicky technology. I used to work for a large company that had a biodigestion plant to treat its organic wastes, and it was forever stinking the place out (and the neighbouring town a mile or so away). When anaerobic digesters go wrong, they can also generate mercaptans, the smelliest substances known to man (methyl mercaptan has an odour threshold of one part per BILLION).

And indeed, nearly everywhere you find large anaerobic digestion plants, you’ll find complaints about the smell.

Of course, the Vineyard Farms operation is quite a small one in terms of bioreactors, so the amount of pungent gas should be relatively small. Their digester will also benefit from having a consistent quality of feedstock (unlike food waste-based plants) which should help to keep the bugs happy. Nevertheless, the energy centre is quite close to a residual area. Any problems with it and Cuxton will soon smell them. 

And so will the customers of Vineyards Farms restaurant and café. You can be pretty sure that in the event of the slightest pong, VF will pull the plug on their biogas plant, meaning that the whole operation won’t really be very “green” at all in energy terms. (Only a cynic would suggest that’s why the vent stack from the energy centre is on the eastern side of the winery, so that any smell would be carried away from it by the prevailing south-westerly wind and blown over Cuxton instead…)

The Air Quality plan says nothing about smells or hydrogen sulphide levels. Perhaps it should.

The Qube Renewables stuff still has a whiff (no pun intended) of the unproven about it. Perhaps Vineyard Farms need to show Medway Council (and Cuxton residents) that this technology is a reliable long-term option with no stinky down-sides.

There are other unanswered questions as well. Where are Vineyard Farms going to store 500 tonnes of pomice? They say they are going to put the stuff in “vacuum bags” for storage. I can’t see this stopping it from decomposing, another possible source of odour when the bags are opened. In reality, I think the pomice will have to be properly dried for storage (off-site? More vehicle movements?) which itself would be energy intensive. Perhaps we need to know more about the pomice storage plans.

Personally, I  think the Vineyard Farms “energy centre” is just another smoke-screen, along the lines of the “there’s-no-traffic-in-Bush-Road” smoke-screen and the “local jobs” smoke-screen and the “our-luxury-£30m-country-club-is-really-just-an-agricultural-building” smokescreen. Maybe the bio-reactor will work, maybe it won’t, but either way they’ll get the “green” box tick they need and if they bin it a year or so into operation, who’s to penalise them? They’ll have what they want by then.

I think they should be made to have a Plan B. Vineyard Farms were quick to write off wind and solar power generation as they allegedly didn’t want to spoil the ANOB, but their country club will do that anyway. So why not put a few wind turbines and solar panels (and a bit of battery storage) at the southern end of Bush Valley, an area which is already disfigured by rows of pylons? 

The pylon run at the southern end of Bush Valley: room for a few wind turbines?

They could easily run the wires underground down to their club-house. Nobody would complain, I think, (not even me!) and it would be a much less risky and less smelly bet than anaerobic digestion as a means of providing green power. And if the biogas option really does turn out to be able to generate 46% of the building’s power needs, why not go for the other 54% anyway, like Councillor Gary Etheridge suggested?

Or is cost the real worry?  Is the “energy centre” really just the cheapest option for a disposable asset, to be quietly dropped when the “tick in the green box” is achieved?

We’ve lost our chance to raise an objection to Vineyards Farms energy plans, but maybe we can still write to our Medway councillors now that they awaiting “more information” from them prior to another planning meeting.

Perhaps we could say that we are concerned about the proximity of the Vineyard Farms energy centre’s anaerobic digestion plant to Cuxton village, and could ask them to ask Vineyard Farms:

·         Are their any other biogas generation units similar to their planned one in current operation in the UK?

·         If so, are there any issues with odour or reliability?

·         Where are Vineyard Farms planning to store their annual 500 tonnes of grape pomice prior to use in the bioreactor?

·         How will the pomice be treated to prevent decomposition during storage?

·         Will an odour or hydrogen sulphide condition be added to the local Air Quality Plan?

·         What are Vineyard Farms’s alternative plans for renewable energy in the event that their biogas plant proves unviable?

Or we could just let Vineyard Farms get away with being unchallenged on this. It could be a bit more than just a rat that we are smelling here…