SECURING ENERGY SUPPLY AND LOWERING THE CLIMATE IMPACT

When Iggesund Paperboard’s mill in Workington, Cumbria switched its fuel supply from fossil natural gas to biomass the result was a dramatic impact on the mill’s fossil carbon dioxide emissions. Overnight they were reduced by more than 190,000 tonnes per year, equivalent to the annual emissions from more than 65 000 cars each driven 20,000 kilometres.

All this was made possible by a 108 million pound investment in a biomass CHP plant. The facility took two years to build and was completed in March 2013.

THE FUEL
Since March 2013 Iggesund Paperboard’s Workington Mill has been powered solely by renewable energy. This requires almost 500,000 tonnes of biomass fuel every year. That is far more than the amount needed to manufacture the paperboard pulp itself, which uses approximately 350,000 annual tonnes of spruce wood from forests in northern England and southern Scotland.

Iggesund is well equipped to handle these greater volumes of biomass. Iggesund Forestry is an integral part of the mill operations and has for decades provided a wood supply service to the mill. This cost-effective infrastructure is now being scaled up to also handle the biomass used as fuel. That is not primarily spruce but rather other types of wood unsuitable for paperboard pulp. Other ingredients in the fuel mix are sawmill by-products, forest residues and energy crops.

To establish a wider biomass fuel supply base, Iggesund has launched a programme to encourage local farmers to grow energy crops (willow).

THE CHP PLANT
The biomass boiler providing Workington Mill’s energy needs is state of the art. It operates at high temperatures and high pressure. Combustion occurs in a bubbling fluidised sand bed. This efficient combustion process together with flue gas treatment restricts airborne emissions to a very low level.

The biomass boiler uses energy from the combustion process to heat water into steam. The high-pressure steam is then led to a high-efficiency turbine, which generates electricity. The same steam is extracted and then re-used to heat the drying cylinders in the board machine’s drying section.

The biomass boiler and turbine can generate more electricity and thermal energy than the mill requires. As a result, not only is the mill self-sufficient in energy but it will also supply renewable electricity to the national grid and can provide heat to the local community.

THE PRODUCTION OF INCADA
For well over a decade now Iggesund Paperboard has been investing to modernise and develop the mill at Workington. This multi-stage programme began in 1999 and has involved an investment of more than 200 million pounds. 

The mill’s board machine is one of the most technologically advanced in the world. The fibre formation system at the machine’s wet end is unique and the method of forming the various layers of paperboard is also extremely sophisticated. Grammages and coatings are rigorously controlled, measured and monitored across the entire width of the paperboard web.

The investments have helped to greatly improve the quality of the Incada product family, which is made at Workington. Energy efficiency has also significantly improved and with the new biomass boiler the mill has taken a unique step – from using 100 per cent fossil fuel to being powered solely by biogenic renewable energy. Incada’s carbon footprint has shrunk dramatically, and from a carbon dioxide perspective Workington Mill is now a global leader.

Iggesund Paperboard is part of the Swedish forest industry group Holmen. As well as producing paperboard the group also manufactures printing paper, has extensive forestry operations and generates energy from renewable sources such as hydro and wind power.