Common misconceptions

Anaerobic Digestion some common misconceptions:

It won’t smell. 

Not even the EA say AD plants don’t smell.

“inherently high potential for offensive odour”

The EA have stated “the treatment of biodegradable waste has an inherently high potential for offensive odour and in our experience it is difficult to prevent odour emissions at all times even when the operator has taken all the appropriate measures.”  The Environment Agency try to keep smells to a minimum, “Whilst we will ensure that the appropriate measures are taken to prevent incidents, in practice this can only minimise their frequency – we cannot guarantee that they will never happen. Whilst this would have little potential to cause problems in the middle of a large industrial area, the proximity of housing means the potential for issues or complaints is greater.”

The reception building would have air extraction through bio-filters which would depend on the size and efficiency of the bio-filters.  The bark and wood chips used tend to form tunnels with use, making the media increasingly less efficient at removing odours and harmful bioaerosols. Bark and wood chip filters only have accidental, uncontrolled micro-organisms, only a small percentage of which are odour-removing (Biofilter co) This type of biofilter appears to be the most basic media and is not selected for the specific type of feedstock.

Traffic would have no detrimental impact on the local highway network or the amenity of residents. No

There could be a huge impact.  Consider the winding nature of Twemlow Lane, the blind bend at the western end, the narrow bridge over the railway adjacent to the entrance, the homes at the eastern end near the entrance, the widths of large tractor/tankers with oncoming waste HGVs, walkers using the public footpaths on Twemlow Lane, cyclists doing time-trials, the likelihood of traffic taking the easier route through Goostrey.

CRES stated 30 trips originally, revised to 42 trips a day, but is this an average over the year and some periods would be much more due to seasonality and limited days available to spread the liquid effluent (due to NVZ regulations). .. plus skips required to deliver/take away packaging, maintenance vehicles etc.

Foodwaste HGV

Pipelines would reduce traffic.

The original use of the site was for fuel storage by the MoD, connected to rail and pipeline for transport, so the site had very low traffic numbers before being abandoned 30 years ago.  The pipeline is not in the application, is not for sale, is being decommissioned and was not designed for corrosive slurry.

The feedstock would be generated locally reducing the need for vehicles using fossil fuel energy.

The feedstock would predominantly be foodwaste which would have to be sourced from considerable distances away.  Waste beer and milk are also to be imported, again not sourced locally.  Maize would be grown specifically for the digesters, taking land out of food production.

Anaerobic digestion is a waste treatment process  

Drumming up objections

Drumming up objections

True yet the official portal for anaerobic digestion, Biogas-info, state  “Anaerobic digestion can be regarded as a chemical process with all the associated risks: flammable atmospheres, fire and explosion, toxic gases, confined spaces, asphyxiation, pressure systems, COSHH, etc. In addition, it also incorporates gas handling and gas storage.”

The catastrophic leak and the failure of the surrounding bund causing flooding into fields and watercourses at Harper Adams in February clearly demonstrate that leaks can happen, investigated by the Environment Agency for the cause.  CRES’s application at Twemlow was the first to propose using existing, old infrastructure; 60 year old tanks and pipes not designed for corrosive slurry, derelict for 30 years.

( TAG Risk Assessment comparison)

Digestate is better than slurry.

Digestate has been shown to be no better than slurry:  Cheshire Grassland Society carried out a study at Reaseheath 2012 and found that slurry’s yield of grass was 7.7 tonnes per hectare but digestate was only 7.3 t/hectare. This was “a prime opportunity to see if AD digestate is really better at providing nitrogen for grass growth compared to the original slurry………the digestate was no better than the slurry.”

A report commissioned by the Soil Association and the World Society for the Protection of Animals also claims digestate from AD plants has no greater value as a fertiliser than slurry.

Buildings would eventually blend into the open countryside without any undue prominence  

Three chimneys and 216 foot long Reception building that would be 40 foot high, would be hard to blend. (A 2 storey house is approx 25-30 ft high).  Farington AD had to raise their exhaust stacks to 82 ft to try and disperse the odours.

It isn’t dangerous

In fact Howard Leberman, when he was the industry regulation policy adviser at the Environment Agency, stated that AD is not a low-risk activity and operators needed to recognise the risks associated with running an AD facility.

“You are dealing with an aggressive working environment,” Leberman warned. “Anybody that deals with an explosive gas/biogas runs the risk of catastrophic issues.  Loss of containment can wipe out an ecosystem, so it’s not low risk and you need to understand the risk at whatever scale.”

Cres said they would not be storing methane, yet the application included a 500 cu.m gasholder 40 feet in diameter and states that ‘the continual digestion of materials gives rise to a continual production in gas. The gas has high methane content.”  Biogas is 60% methane and would be continuously produced in the 5750 cu.m (60 yr old) tanks, it is hard to see that it would not be a potentially hazardous environment.

view from Goostrey bridge

view from Goostrey bridge

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