Multiple feestocks power Sweden

June 2, 2014 – On the way to the World Bioenergy Conference
in Jonkoping, Sweden, Canadian Biomass joined a tour of international delegates
keen to learn how the region is heated and energized. The first stop was a CHP
plant in Sodertalje, which supplies several large southern suburbs of Stockholm
with district heating. Soderenergi is one of the largest district heat
producers in Sweden.

The first plant on the site was fuelled on coal in 1982. But
when a carbon dioxide tax was introduced in Sweden in the early 1990s, the
three boilers were converted for use with biofuels and converted waste fuels.
These three boilers generate around 100 MW each.

In 2010, a CHP plant was added to the site. This new
facility produces 200 MW of heat and 85 MW of electricity. It is mainly fuelled
by forest residuals but also by recovered waste fuels. It is Sweden’s largest
bio-fuelled co-generation plant and has a workforce of 130 people.

The combined approach makes sense in Sweden since the long
winters require the heat that would otherwise be wasted in the power production
process. The electricity is produced by heating water to steam in the large
boiler. The steam turns the turbine, which powers a generator that produces
electricity. This electricity is fed to the power grid and the surplus heat is
used in the district heating network to heat nearby homes. Once the homes have
been heated, the heat (hot water) returns to the power plant to be reheated.

The CHP plant is fuelled primarily with forestry chippings
and an increasing amount of recovered waste wood from building sites and
demolitions, which currently makes up 45 per cent of the fuel. Other fuels
include fuel timber that is unsuitable for other purposes, recovered crushed
waste material that comes from office and industrial sources (paper, plastic
and wood), wood pellets, peat, tall pitch oil (a by-product of the paper pulp
making process) and a small percentage of heating oil used when the winter is
extremely cold.

The plant’s biggest challenge is the logistics of getting
the fuels to the boilers. They are sourced from 40 suppliers in ten countries
and all over Sweden and come by boat and rail. The port, though close, is
small. The forestry residuals arrive by rail but the terminal is not on site
and the loads have to be transported onto trucks to be taken to the site.
Onsite storage is limited to about three days so logistics is a continuous
challenge.

For more updates on World Bioenergy, go to
www.canadianbiomassmagazine.ca .