The flue gases from the power station are scrubbed and a filter removes 99 per cent of the ash and dust particles. Fifty tons of ash per hour is produced and is used by Alborg Portland in the manufacture of cement and concrete and for road building. Nitrogen oxide emissions have been reduced by 50 per cent when compared with the original emissions from burning coal . Desulphurisation removes more than 95 per cent of the sulphur dioxide in the flue gases. This is washed with lime-water to produce gypsum - 250 tons every 24 hours. The gypsum is sold to and used by the Gyproc Group, the largest manufacturer of plasterboard in Denmark. Also, 3000 tons of pure sulphur are sold by the refinery to a sulphuric acid manufacturer, Kemira. A project still under consideration is to use more of the waste heat in a massive greenhouse.