PPI (PULP & PAPER INTERNATIONAL) MAGAZINE: The power of pulp

A new turbine at Värö is just part of Södra Cell's plans to become a 'pulp company with a lot of excess energy'

June 2007
By Justin Toland, Editor

Sweden's Södra Cell has long had a reputation for being one of the most environmentally conscious pulp and paper companies. Fifteen years after pioneering large-scale totally chlorine free (TCF) bleaching, the firm is one of the first pulp manufacturers to become a net producer of electricity, all derived from renewable resources.

The addition of a new turbine at each of its Swedish mills (Mörrum, Mönsterås and Värö) will enable Södra to produce 1.7 TWh of electricity this year, compared with forecast electricity consumption of 1.6 TWh. The new turbines cost SEK 571 million ($84 million) in total, for an additional generating capacity of 415 GWh.

Södra Cell has calculated that its Swedish electricity'business' will be worth SEK 705 million in 2007: "Not income, just a non-existing manufacturing cost," explains managing director, Sten Holmberg.

The Södra Cell MD notes that the new turbines will have an internal rate of return (IRR) of more than 20%. The company's benchmark is 12%.

Technical director, Roland Löfblad, explains Södra Cell's involvement with the CHRISGAS project in Sweden

Investments at Väro

Södra Cell Värö started up in June 1972, which makes it the newest mill in Sweden. The facility produces 400,000 tonnes/yr of softwood TCF pulp. ("There is no quality difference between TCF and ECF pulp," points out mill manager, Gunilla Saltin). Last month, the mill celebrated producing its 10 millionth tonne of pulp.

Värö is aiming to boost output to 425,000 tonnes/yr in April 2008 with an investment of SEK 220 million in a new causticizing plant and the installation of a shoe press on the drying machine. The extra output will all be of the quality known as Södra Black 85Z (hence the project is dubbed'425 Black'). This product is particularly suited to the needs of tissue paper producers, a segment of the market in which Södra aims to continue its expansion. In 1999, Södra Cell sales to tissue were 137,132 tonnes/yr (or 11% of total sales); by 2006, that figure had risen to 557,692 tonnes/yr (28% of total sales).

More than SEK 285 million has been invested by Södra Cell Värö mill in the past two years to increase energy efficiency, electricity production and district heating capacity.

Some SEK 189 million of that figure went on a new steam turbine and associated equipment, installed in November and December 2006. Plant and maintenance manager, Thomas Karlsson, explains that the seeds of the project were sown when a new recovery boiler was installed at Södra Cell Värö in 2000: "It was designed to have more steam pressure than we could use at the time. We didn't imagine we would be able to make use of it so soon."

The aim of last year's steam turbine project was to increase electricity generation capacity from 33 MW to 46 MW. Since there was no suitable turnkey supplier option, Södra Cell opted to coordinate a basket of deliveries from a range of suppliers (see sidebar). The largest contract, for the turbo generator, was awarded to Skoda Power of the Czech Republic. "We are happy with the results," says Karlsson.

The scope of the project saw the pressure in the recovery boiler increased from 60 to 85 bar, new high-pressure steam distribution and steam conversion stations were installed, as was a new 60 MW back pressure turbine, high voltage-switchgear, a connecting transformer and electrical protection equipment. A new turbine hall and electrical rooms were constructed to house the gear.

The first test run took place on December 30, 2006. The equipment is running successfully and is capable of delivering up to 7 MW to the external grid. "The actual amount depends on the mill steam situation and spot price for electrical energy," explains Karlsson.

Södra Cell Värö mill celebrates producing 10 million tonnes of pulp

More power in the pipeline

As Sten Holmberg indicates, Södra Cell is planning further investments in energy generating capacity, inspired by the projections for further hikes in electricity prices, in combination with Sweden's green certificates scheme (see sidebar).

Three new windmills are set for installation at Värö in 2008. Costing SEK 81 million in total, they will produce 6 MW of power between them, or 22 GWh of additional energy.

This first investment in wind power could be the start of something much bigger, explains technical director, Södra, Roland Löfblad. Within five to six years the firm plans to have 3 x 2 MW wind power units at Mörrum and Mönsterås as well. It is also looking at the possibility of building wind farms away from its pulp mills. The results of a pre-study for a project in southern Sweden involving some 30 windmills will be analyzed by the board of Södra later this year. "We could be a very big wind power producer," suggests Löfblad. "[Södra CEO] Leif Brodén has been talking about a possible investment of up to Euro 800 million ($1.16 billion)."

New technology

Södra Cell has applied to the Swedish environmental court for a permit to produce lignin powder at Mörrum mill, as part of a joint research project with STFI-Packforsk. Known as LignoBoost, the project is designed to reduce the load on the recovery boiler, increase pulp output at the mill from 460,000 tonnes/yr to 560,000 tonnes/yr and also produce 70,000 tonnes/yr of lignin powder (equivalent to 350 GWh of energy). This powder could be used to fire the mill's limekiln, as a fuel source for a CHP plant, or as a base for green chemicals.

A decision on the permit is expected from the Swedish environmental court within one year. Södra's board will then decide whether or not to proceed with LignoBoost.

If that scheme, and other proposed investments, does go ahead, within six years Södra could have 1.4 TWh of excess energy to supply (see sidebar). This would make it not an energy company, says Löfblad, but, "A pulp company with a lot of excess energy."

Another new technology that Södra is backing is black liquor gasification (BLG), through its support for Chemrec's research work at Piteå in northern Sweden. Löfblad says that BLG should be able to move from the current pilot scale to the demonstration plant stage within three to four years. If attached to a pulp mill, a BLG plant could generate 17,000 m3 of DME (biodiesel) -- equivalent to 20% of all diesel used by the Södra group, including for transport. More pulp could also be produced.

It is not possible to produce both lignin powder and biodiesel through gasification at the same mill. "Of course, you could have lignin powder at one mill and BLG at another," notes Löfblad.

With an eye on the long-term, Södra is also one of 17 companies supporting research into what its technical director calls, "A technology for the future" -- CHRISGAS. Short for Clean Hydrogen-rich Synthesis Gas, CHRISGAS could generate biodiesel on a much larger scale than BLG technology (170,000 m3 is the ballpark figure). A CHRISGAS plant can also be built independently from a mill.

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