Plans have been published for a pyrolysis plant on the disused food waste biodigester site in the industrial areas on Coder Road (25/00309/FUL). The plant comprises a shredder and dryer and a closed vessel anaerobic digester that breaks down materials in a closed vessel. One product is methane, which is used to generate electricity to operate the plant with any excess being exported using the existing cable to Squirrel Lane substation. The second product is biochar, a carbon rich material used to improve agricultural soils, where it can also help to reduce flooding, and in compost.

Broadly, I support this application. It provides a solution to a long empty brownfield site. It is at the leading edge of green technology. It continues Ludlow’s tradition of being a green thinking town. And it stores carbon for hundreds of years if not longer. There is, however, much more to learn about this application. There are several lengthy technical reports, not all of which I have read in detail.

The Coder Road biodigester, cutting edge innovation at the time, was taken out of service by the climate change sceptical leadership of Shropshire Council in 2013 after the site ran out of grant funding. Shropshire Council is now the applicant for this plant, to be paid for using a public works board loan. As the applicant is the council, the application will automatically be referred to the Southern Planning Committee for a decision, probably in March.

The plant will be on an existing industrial estate and the anticipated traffic of two or three vehicles a day will not add significantly to the already heavy traffic on Parys Road.

The proposed pyrolysis plant will be a facility specially designed to convert organic waste or biomass materials into biochar through the process of pyrolysis. Pyrolysis is the thermal breakdown of materials (in this case plant materials) in the absence of oxygen. The heat drives off volatile gasses and oil and what is left is mostly carbon in the form of char.

The site will accept c.12,500 tonnes of biomass, mainly virgin wood, arboricultural arisings from felling or management of trees, and compost oversize materials such as branches. This feedstock will arrive wet (c.50% moisture content) in vehicles c.26 tonnes with potential for smaller deliveries in vehicles c.7.5 tonnes. It is anticipated that deliveries to the plant would be around 700 vehicles over a 12 month period (approximately 13 per week or 2-3 per weekday).

The pyrolysis process takes the wet feedstock and processes it using a wood chipper, prior to drying. This takes place in a new structure at the back of the existing biodigester building. The dried feedstock has around 10% moisture and has a lower volume. It is fed into the pyrolysis plant and heated in the absence of oxygen.

The pyrolysis gases are then combusted to provide the primary heat for the process (drying and energy generation), whilst the residual char is quenched and removed as a product. The plant will produce approximately 1700 kW of heat energy, 70 kW of electrical energy and  about three tonnes of biochar a day.

Biochar is typically between 60% and 80% pure carbon. One tonne of biochar effectively stores between 2 to 3 tonnes of CO2. Biochar can remain in soils or materials for hundreds, and even thousands of years without degrading. This is a method of removing carbon from the atmosphere that is much more efficient than anaerobic digestion. Pyrolysis consumes the feedstock faster and biochar stores carbon for much longer, centuries than the several years storage than the digestate produced by anaerobic digestion. Nearly all anaerobic digestion plants capture methane (CH4), one of the most powerful greenhouse gases, though storage of agricultural waste such manure can lead to unmonitored methane emissions. This pyrolysis plant will use all the methane for energy production. The reports state that CO2 emissions will be low.

Waste gases will be discharged through a 10m stack. The air quality report states that even in the most extreme modelling of discharges, they will not have any impacts on people living in the area or on ecology. “The potential for offsite odour is considered low.”

The noise report, which could have benefited from a final edit, suggests that all that might be heard from the plant is a low hum at night. I would add to this that the site is 200 metres from the nearest house and the constant drone of the A49 will drown out any noise except maybe between midnight and 4am. Biodiversity net gain, as required by planning rules, will be achieved by planting of native trees and shrubs, and “management of existing low grade areas of vegetation to encourage growth perhaps including wildflower plants.” There is a very fine oak on this site but this development will have no impact on the tree. I am sceptical about the tree planting. Trees have to thrive and the space allocated is too small.

The site will employ two full time equivalents of staff. The plant will operate continuously but staff will only be on site 8am to 5.30pm Monday tor Friday, during which deliveries will arrive and the woodchipper and dryer will operate. On Saturday, there will be staff doing cleaning etc.

An application is being made to the Environment Agency for an environmental permit.

2 thought on “Plans published for biochar pyrolysis plant at Coder Road biodigester”
  1. Interesting proposal but who wrote the application?
    “Biochar is typically between 60% and 80% pure carbon” is not possible, should be contains elemental carbon.
    The figures indicating the number of atoms in a molecule are in the incorrect position – where they have been written is the mathematical position to indicate squared etc.
    Is there a cost benefit analysis attached to the application?Michael

    1. Pure carbon can exist and it has many allotropes. Soot, for example, is an amorphous form of pure carbon as is charcoal, not to mention diamond. The carbon might be mixed with other elements but does have to be bonded to them. I have questions about the elemental composition of the biochar, though it will depend on the input material.

      I don’t know what you mean by “the figures indicating…”

      The application is written by Enviroconsult, based near Shifnal.

      The cost benefit analyis for the finance is linked below. Note that financial matters are not normally a material planning consideration. If an applicant doesn’t have a good business case, it’s their problem. The business case looks good but as always the numbers are ideal circumstances. Life is not ideal but I think there is enough margin to stack up the numbers.

      https://shropshire.gov.uk/committee-services/ieListDocuments.aspx?CId=125&MId=4843&Ver=4

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