The forest industry is a significant consumer and producer of energy. In 2017, for example, Metsä Group produced 15 per cent of all renewable energy in Finland. The forest industry is an energy-intensive sector, which makes energy efficiency all the more important. The sector has achieved excellent results: it has voluntarily increased the energy efficiency of its operations by around 5.4 terawatt hours per year between 2008 and 2016. This corresponds to the amount of energy needed to keep a sauna warm continuously for 104,000 years! Continuous improvements in energy efficiency reduce emissions, but companies also benefit financially from their energy efficiency measures.
Improving energy efficiency is part of the day-to-day operations of Metsä Group's business areas. Measures to improve energy efficiency range from major investments to smaller efficiency improvements. To celebrate the Finnish National Energy Saving Week from 8 to 14 October, we compiled few examples of recent measures to improve energy efficiency at Metsä Group.
CASE METSÄ WOOD:
Energy efficiency through the renewal of drying machines
During winter and spring 2018, Metsä Wood implemented projects to modernise drying machines at the Kerto mill in Lohja and the Suolahti spruce plywood mill. The drying machines are the mills' largest consumers of heat and electricity, which is why their modernisation improves the entire mills' energy efficiency. During the projects, the air, heat and moisture management of the drying machines was improved, in addition to modernising line control and the moisture and density measurements of veneer. As well as improving energy efficiency, the goal is to improve the quality of dried veneer and increase production volumes.
"The projects were implemented on schedule, and the modernisation made the drying process more efficient in terms of both steam and electricity," says Jussi Ekman, Development Manager at Metsä Wood.
If the goals set for the projects are achieved, similar modernisation projects will be considered for the other drying machines at Metsä Wood's mills in Lohja, Suolahti and Punkaharju. The implemented investment projects were worth around EUR 1 million.
CASE METSÄ FIBRE:
The world’s most energy-efficient pulp mill
Metsä Fibre’s bioproduct mill in Äänekoski has been operating since 2017. Thanks to its equipment solutions, the mill is the world’s most energy-efficient pulp mill, and it uses no fossil fuels. Even the forklifts used at the mill run on electricity.
The bioproduct mill produces 1.8 terawatt hours of electricity per year, which represents around 2.5 per cent of Finland’s annual energy production. The mill is more than self-sufficient in electricity: it produces 2.4 times the amount of energy as it uses. Its start-up in autumn 2017 increased the amount of renewable energy in Finland by 2 percentage points. The Ministry of Employment and the Economy granted EUR 32 million for the mill’s energy concepts that involve new technologies and renewable energy production.
CASE METSÄ BOARD:
A new type of heat exchanger for Metsä Board’s mill in Kaskinen – first of its kind in Finland
As of October 2018, Metsä Board’s pulp mill in Kaskinen will make use of a new, more energy-efficient technology for recovering heat from the flue gases generated by its power plant. The heat exchanger to be installed at the mill is first of its kind in Finland. The replacement of the heat exchanger is also the first project to receive energy subsidy for new technologies from Business Finland. The subsidy covers 30 per cent of the nearly EUR 600,000 investment. The replacement aims for annual energy savings of around 10,800 megawatt hours. This corresponds to the annual energy consumption* of nearly 1,500 single-family homes with four inhabitants.
This new type of vacuum tube heat exchanger replaces an old technology based on the use of ribbed pipes. In addition to increasing energy efficiency, the new heat exchanger is intended to resolve corrosion problems related to the old technology.
“Heat exchangers based on ribbed pipe technology tend to corrode because of the condensation of acid gas. For this reason, they need to be replaced at regular intervals. The new vacuum tube heat exchanger does not have this problem, which is why it offers a long-term solution for recovering heat from flue gases. As a new technology is involved, this is also a research project for us. If the technology proves to be functional at Kaskinen, it can later be introduced at other mills,” says Matti Korhonen, Energy Efficiency Manager at Metsä Board.
* Vattenfall: annual energy consumption, single-family house with no electric heating, ordinary level of equipment and conveniences (120 m², four people).
CASE METSÄ TISSUE:
Long-lasting work brings results: Metsä Tissue’s mill in Mänttä has improved significantly its energy efficiency
Metsä Tissue’s mill in Mänttä, Finland, produces toilet and household paper, hand towels, industrial towels and as well as cooking papers. The mill has three tissue paper machines, a greaseproof paper machine and 11 tissue paper converting lines. The mill’s production is highly energy-intensive, as the drying processes for tissue and cooking papers consume considerable amounts of energy in the form of steam and gas. Energy expenses are the Mänttä mill’s second-largest expense item after raw material costs.
The energy efficiency measures implemented at Mänttä and optimation based of that in recent years have decreased the mill’s steam, gas and electricity consumption by five per cent per tonne of paper produced over the last seven years. Its specific water consumption has decreased by 28 per cent over the past five years.
“The savings were achieved by reviewing all processes and improving the measurement of their energy consumption,” says Jyrki Leppäaho, Production and Energy Engineer at the Mänttä mill.
Now, optimal energy consumption values have been determined for all stages of production, which process operators can influence. Thanks to the new system developed as a tool for the mill, the usage of steam, gas, electricity and water can be monitored in real time.