The pyrolysis plant’s environmental footprint is comparable to that of a small-scale biofuel boiler (5–10 MW). The plant will be responsible for a certain amount of emissions to air, noise and waste.
- The flue gases from the combustion of the coke and non-condensible gases contain dust and nitrogen. Dust will be removed using an electrostatic filter. Regular control measurements will be taken to verify that values fall within the limits of the permit. The limit values are stricter than those set out in EU Directives for biomass-fired boilers in the same size class.
- The area around Kastet is already subject to noise from local industries and from traffic on the roads and railway. However, the pyrolysis plant will not make any major difference, with estimates showing a theoretical increase of around 0.3 dBA to the overall noise levels locally. Its immediate neighbours will find it very hard to tell whether or not the pyrolysis plant is in operation. Noise levels will fall within the guidelines recommended by the Swedish Environmental Protection Agency.
- The residual products will mainly derive from the purification of the flue gases (bottom ash and fly ash). The volume will amount to around 1,000 tonnes per year.
- The number of trucks coming and going around the sawmill site will decline slightly, because the sawdust will be used on site rather than being transported elsewhere (the sawdust has previously been used for pellet production and as a fuel for district heating). The pyrolysis oil will be transported from the plant by tanker.
- The bio-oil has a strong, slightly smoky odour. To avoid the risk of nuisance odours, the bio-oil storage facility will therefore be fitted with filters for the exhaust air.
- The risk of dust formation is judged to be low because the sawdust is largely handled within closed systems.
- There are no process water discharges from the plant.
The overall assessment is that the pyrolysis plant will have limited environmental impact.