FAQs
Q. What is the style of treatment proposed?
Q. How will the process work?
Q. Which particular version of the pyrolysis process is proposed?
Q. How is the process different from incineration?
Q. What are the pros and cons of pyrolysis compared with incineration?
Q. If the process it is not incineration why is the proposed plant subject to the EU Waste Incineration Directive (WID) regulations?
Q. Why build the plant at Haybridge?
Q. What alternatives have been considered?
Q. Will there be any visible or non visible emissions from the site?
Q. What effect will "the Wells Bowl" and temperature inversion have on dispersal of the emissions?
Q. Will there be smells and noise from the site?
Q. So will it be quieter than the current aggregates recycling activity?
Q. What are the impacts of the proposal on traffic movements in the area?
Q. Are there any impacts on local ecology and the adjacent Site of Scientific Special Interest (SSSI)?
Q. Could an accident cause pollution to the River Axe?
Q. Could an accident lead to serious airborne pollutants being released?
Q. What would be the risk and consequences of a major fire?
Q. Will the plant be at risk from flooding?
Q. Will the emissions from the facility lead to acid rain over the Mendips?
Q. Will the facility detract from what is a popular tourist area?
Q. How does the proposal sit with waste planning policy and guidance?
Q. Will there be any planning gains from the proposal?
Q. Will the proposal divert waste from recycling?
Q. What is the style of treatment proposed?
The plant is based upon a process known as Pyrolysis. Pyro means heat and the process of converting organic and inorganic materials to gas by the application of heat in the absence of oxygen is known as pyrolysis; in simple terms a form of cooking rather than burning (see "How will the process work"). Pyrolysis has been in industrial use for many years and is widely used in the modern petro-chemical industry where the process is called "destructive distillation" or "cracking".
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Q. How will the process work?
The proposed facility would use prepared waste materials as a fuel which would be fed into a hot chamber where they would be converted to gas and a very small quantity of residual ash.
Because the process occurs without oxygen there would be no opportunity for any burning to take place. The small amount of emissions from the plant would be carefully controlled and measured to ensure compliance with high standards set by the regulating authority (the Environment Agency).
The synthetic gas (or "syngas") is a clean gas similar to natural gas used in the home but the plant would use it in specially designed engines to generate electricity on site; the electricity would then be supplied to the National Grid for public consumption The heat produced during the process would be recycled on site e.g for the preparation of the waste fuel. Any excess heat could, if required, be used by the adjacent paper mill or in the local leisure centre in Wells where it could replace or supplement the heat needed by these facilities. In these circumstances the plant would be a Combined Heat and Power plant (CHP plant).
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Q. Which particular version of the pyrolysis process is proposed?
The Company is still evaluating the selection of the gas conversion process. There are at least three different companies that supply versions of this technology in the UK but the current thinking is to adopt one of these known as the GEM process. This is a mechanically simple version that can be built to a modular format using standard units.
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Q. How is the process different from incineration?
Essentially incineration is a process that "burns" material, in the presence of oxygen, to produce heat that is converted into steam which is then used to drive steam engines or turbines to produce power.
The pyrolysis process, however, "cooks" the material in the absence of oxygen to produce a gas which, after being cleaned, is used in an engine or turbine to produce power.
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Q. What are the pros and cons of pyrolysis compared with incineration?
Incineration has the following advantages:
- Lower capital costs per tonne processed
- The technology is simple
- Steam turbines offer lower operating costs
Incineration has the following disadvantages:
- Often requires large facilities and a large chimney
- Less efficient conversion of the fuel material to power generated
- There is a lot of ash left over from the process
- Most importantly, incineration requires expensive clean-up controls
Pyrolysis has the following advantages:
- More efficient production of power
- Process is more controllable and hence emissions are much lower
- Because small plants are viable they can better serve local communities (the proposed facility has only about 10% of the capacity of most mass burn incinerators)
- A very low ash output due to the use of pre-prepared fuels and the nature of the process
Pyrolysis has the following disadvantages
- It doesn"t suit large tonnages (the capital cost per tonne is more expensive)
- It is a slightly more complex process - although the principles are simple
- People are a little unsure about them as a waste management option because there are not many operating at the present time
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Q.If the process it is not incineration why is the proposed plant subject to the EU Waste Incineration Directive (WID) regulations?
The EU Waste Incineration Directive (WID) was written in order to prevent environmental pollution and govern the manner in which all waste was managed in facilities that utilise waste material as a fuel. The directive therefore includes all existing and anticipated future waste treatment technologies in order to close any potential "loopholes" in the rules and imposes strict limits on emissions from any such facility in the European Union.
The Directive is also relevant to the engines proposed for the site at Haybridge because, although they would be using gas that would be cleaner than natural gas, it is derived from processing waste.
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Q. Why build the plant at Haybridge?
1. The site is located centrally to a waste catchment area with no disposal facilities for a 16 km radius. Within the Somerset County Council defined catchment area (for Haybridge) around 125,000 tonnes of suitable commercial and industrial waste is generated which is currently sent to landfill.
2. It is an existing waste management site (recycling demolition and construction wastes) and adjacent to other industrial activities. The proposal offers the opportunity to improve the appearance of the site and to reduce the impact of its use on the local community caused by noise and dust emissions and to implement improved access arrangements to the site
3. The site has ready access to the primary road network (A371)
4. The site has the benefit of ease of access to the local electricity transmission network
5. The site is screened from all but the closest views by a combination of natural vegetation, landform and existing buildings
6. The Haybridge site offers the potential to use the excess heat from the process in the local community at, for instance, the paper mill, Wells Leisure Centre and in other adjacent properties (heat, unlike electricity, cannot be transported efficiently over long distances)
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Q. What alternatives have been considered?
Alternative sites and technologies have both been considered.
In terms of technology, the waste streams to be processed are non recyclable high calorific value wastes such as plastics, timber, paper and paper fibre from the general commercial, industrial and demolition and construction sectors. These are not suited to bio degradation processes or incineration because of the quantities to be processed and the emission implications. Disposal to landfill, where these wastes currently end up, does not fit with current legislation and guidance. There are alternative pyrolysis technologies to the preferred GEM process but the adoption of any of these would not lead to any fundamental changes to the proposed plant, its emissions or method of operation if they were to be used instead.
Consideration has been given to the possible use of other sites identified for industrial development in local plans nearby. For instance the Morlands site at Glastonbury and the Southwood Waste Management site at Evercreech. These were rejected because of transport issues, planning and environmental reasons and leasehold complications. Additionally they had limited opportunities for utilisation of the heat from the facility and had significant costs associated with connecting to the national electricity grid.
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Q. Will there be any visible or non visible emissions from the site?
All gaseous emissions will be through a small single flue stack and well within the stringent environmental limits as regulated and monitored by the Environment Agency. There are unlikely to be any visible emissions from the stack.
The non-visible emission limits are based on the lowest achievable concentrations of pollutants, rather than just the lowest that are acceptable in terms of health. 99.99% of the flue gas is comprised of nitrogen, oxygen, steam (water vapour) and carbon dioxide. Of the remaining 0.01%, around 94% of that is either carbon monoxide or oxides of nitrogen.
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Q. What effect will "the Wells Bowl" and temperature inversion have on dispersal of the emissions?
Responding to comments from the Waste Planning Authority and consultees (including the public) further studies have been completed by independent consultants on the dispersal of emissions.
The approved computer model used the local Mendip Weather Eye data for wind direction, and took account of the ground terrain over an area of 10km. Temperature and time of year were also considered to define a "worst case" prediction. The results of this exercise have proved that the location of the site is suitable and, also, that the presence of the Mendips is beneficial to the dispersal effect of the wind.
"Temperature inversion" as a concept is irrelevant to the physical (temperature) characteristics of the flue gas from the site. The flue stream would need to cool far more rapidly than is possible, even on the coldest of days, for any likelihood of it being "trapped at a low level.
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Q. Will there be smells and noise from the site?
There would be no smells or unpleasant odours arising from the processes or from the pre-prepared waste material that would be delivered to the site and used as a fuel. The plant would be fully enclosed in purpose made double skinned buildings and operated under negative pressure (a method used to ensure air is drawn into the building constantly to ensure no outward escape). All emissions including the air moving through the buildings would pass through a thermal oxidiser process to remove any odours before venting to the atmosphere.
The noisiest part of the plant"s operation would the delivery, unloading and fine shredding of the incoming waste streams. However, these activities would be carried out from Monday to Saturday and then only during normal daytime working hours. The small scale of the plant will mean that deliveries would be few and all unloading and shredding would take place within the buildings.
A detailed and independent analysis has been conducted of the anticipated noise levels and is on the public record as part of the planning application. Calculations of the noise impact around the site perimeter of the proposed operations suggest that there will be little or no increase on current levels.
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Q. So will it be quieter than the current aggregates recycling activity?
Yes it will be. The current activity is not undertaken in buildings and is much, much noisier. Because the proposed facility will generate power 24 hours a day, it will need to be quiet enough not to cause a disturbance to the nearest neighbours on a hot summers night when they may have bedroom windows open. For this reason the facility will also be quieter than its immediate industrial neighbours.
A detailed noise analysis has been performed. It demonstrates that the target noise emissions set by Somerset County Council (and based on the above criteria) can be complied with. Once the site is operational the noise impact will be checked to confirm that it complies with the County Council targets to prove that it will not be disruptive to the site"s neighbours.
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Q. What are the impacts of the proposal on traffic movements in the area?
L A Moore Ltd (LAM) is authorised to operate 10 lorries from the Haybridge site. It is also authorised to process demolition and construction waste. Where possible the waste that would be processed by WP2 will utilise LAM vehicles on their return trips to base; these would otherwise be returning empty. By using this system there will be only a very marginal increase in traffic movements in the area (6-8 per day).
In order to minimise the impact of these additional HGV trips transport of waste to the site will only take place during working hours. Both the mill and LAM already transport sufficient materials to provide about 50% of the waste that could be processed at the proposed facility.
To further improve the situation at Haybridge the proposed development includes adding an entrance at the western end of the site on Titlands Lane. This will facilitate a one way traffic system through the site, hence the traffic flow from the site past the houses on Glencot Road and at its junction with the A371 will be almost halved. This is a significant improvement over the current access arrangements for the site.
On a broader scale the proposed development will reduce the overall number of current waste vehicle movements because it will eliminate the need to take around 40,000 tonnes of waste away from the catchment area to landfill sites elsewhere within Somerset and beyond
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Q. Are there any impacts on local ecology and the adjacent Site of Scientific Special Interest (SSSI)?
The proposed facility will lead to significant improvements to the existing industrial site, designing in measures such as badger and otter pathways and including additional planting.
The Site of Special Scientific Interest (a geological site) at the Glencot Road end and adjacent to the site roadway will not be disturbed at all by the proposed development but the company has proposed measures for its protection and maintenance following discussions with Natural England. As regards other ecological interests e.g sites at some distance from the Haybridge, as well as bats and slow worms, the reports submitted by the Company to Somerset County Council demonstrate that these will not be harmed.
The Company is considering the possibility of providing a visitor centre in the proposed buildings for those interested in learning more about the WP2 plant and the use of non-recyclable waste as a source of renewable power.
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Q. . Could an accident cause pollution to the River Axe?
It is hard to envisage the circumstances under which this could lead to pollution of the river. The waste materials are in solid form and would be stored and processed in bunded silos under cover. Any fluid run off will be trapped and piped to a waste tank for disposal. Any chemicals or fluids stored on site will likewise be stored in bunded stores.
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Q. Could an accident lead to serious airborne pollutants being released?
Again this is hard to envisage. The flue stack will be constantly monitored for abnormal emissions with an automated alarm and shut down capability. The pyrolysis process and overall facility can be closed down in under a minute should problems arise. Simply stated, the plant is too small, and the quantity of gas held at the site at any one time is too low, to create an accident of any significant scale.
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Q. What would be the risk and consequences of a major fire?
We judge the risk of a major fire to be low. The feedstock silos and operational procedures for fuel preparation have been designed to take account of and eliminate the risk from the storage of shredded and dried waste. As is expected of any industrial operation the plant will need to comply with all appropriate fire regulations.
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Q. Will the plant be at risk from flooding?
No. The plant would be sited well above the flood plain of the River Axe. In the past flooding has never occurred at the site of the railway yard and station.
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Q. Will the emissions from the facility lead to acid rain over the Mendips?
The emissions will be well within approved limits and constantly monitored and would be so small that any impact would be almost impossible to detect. Emission studies carried out by WP2 confirm this.
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Q. Will the facility detract from what is a popular tourist area?
We do not believe so. Enclosing the facility in a low, purpose built building that would be well screened by trees and existing buildings will eliminate any negative visual impact. This approach will also improve visual amenities in the area by removing what is currently an open, unsightly aggregates recycling site.
The actual operation of the site would not be noticeable to the extent that it would have any effect on the tourism industry.
In addition, WP2 has offered to assist in improving the proposed Multi User Path that skirts the site which will enhance the recreational cyclepath facilities for visiting tourists and local residents.
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Q. How does the proposal sit with waste planning policy and guidance?
The proposal conforms to a range of policies and guidance, including;
- Re-development of brownfield land
- Sustainable development and job creation in the local community
- Located on the edge of an urban area, in close proximity to the origin of the wastes to be treated
- Good access to the primary road network
- Small scale, new generation advanced thermal treatment facility
- A local solution to a local problem
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Q. Will there be any planning gains from the proposal?
There are six key planning gains proposed for the area, over and above the generation of renewable electricity, from locally derived wastes;
- There is the opportunity for heat to be delivered to local organisations (for example the Wells Leisure Centre, potentially helping to reduce the running costs of the facility)
- The contemplated visitor centre would provide a focal point for education on the modern approach to the management of waste, local ecology and environmental issues
- The development delivers improved road access to and from the site
- There is scope to facilitate an extension of the cycle path through to Titlands Lane
- An overall reduction in vehicles transporting waste around the area
- The current noisy and intrusive site activities will be displaced by a modern facility operating in purpose made buildings to the highest standards of environmental control
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Q. Will the proposal divert waste from recycling?
The City of Wells is understandably proud of its high waste recycling record for household waste which is claimed to be 55%. Although the proposed plant could assist in the beneficial use of the remaining 45%, which will contain high calorific value waste, this is currently sent to landfill in another local authority area. However, the City"s recycling rate will not be reduced by the proposed development because the intention is to treat commercial and industrial wastes that cannot be recycled and would otherwise also go to landfill.
The proposed facility at Haybridge offers a more environmentally sustainable solution for these wastes than landfill by recovering energy from the treated waste materials and managing them close to their origin.
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