Home Mills & Technologies Power & Energy The clean, energy efficient pulp and paper mill

The clean, energy efficient pulp and paper mill

Investment in recovery boilers and other energy efficient systems has increased electricity self-sufficiency of Mondi's mills far beyond EU requirements, also enabling contributions to local power grids.

At Mondi, we are committed to reducing energy inputs and greenhouse gas emissions because it's good for the environment and business. To help us achieve ambitious energy targets, we've been investing for years in modern recovery systems in pulp production and the efficient use of biomass by-products. Completed projects such as those at Mondi ?wiecie (Poland), Mondi Frantschach (Austria) and Mondi Ružomberok (Slovakia) are already reaping benefits, and further energy recovery projects are currently being implemented.

As a result, Mondi has achieved around 96% electricity self-sufficiency across our Group's pulp and paper mills and significantly reduced the share of fossil fuels used: biomass-based renewable sources make up around 65% of total fuel consumption across Mondi's pulp and paper mills.

"With this 65% share of biomass-based renewable sources, we already exceed EU requirements by far," says René Stadler, Category Head of Energy, Mondi Group. He is referring to the 2012 EU Energy Directive, which set EU member states the target of obtaining 20% of their energy from renewable sources by 2020. New targets are currently under discussion, aiming for a 27% share of renewable sources by 2030.

Energy strategy – increasing efficiency and electricity self-sufficiency, while lowering greenhouse gas emissions – is an important focus area of our sustainability model, Growing Responsibly, and is reflected in our investments. We continually invest in state-of-the-art technologies, such as recovery boilers and biomass utilisation, for energy-consuming plants and facilities.

There are various reasons behind such strategic investments in our plants. These include both improving operational performance and lowering energy intensity – the specific energy consumed in production. This reduces external dependencies and facilitates more flexible participation in the energy markets. A positive side effect is the ability to feed excess process heat into external district heating networks. In doing so, Mondi is helping local communities achieve their own energy targets.

These efforts are in line with our strategy of electricity self-sufficiency and greenhouse gas emission reduction. "Long before regulatory requirements were introduced, we implemented measures that continue to have an effect to this day. They include, for example, the audits and benchmarks we use to compare the plants," says René Stadler. "Over the years, this has allowed us to implement systems and measures that have significantly improved our energy management."

"For our part, we've implemented more measures than legally required. By over-delivering, Mondi is contributing significantly to achieving these important energy targets," explains Stadler.

An efficient production process is the basis

Erwin Zlabinger, Energy Manager, Mondi Group, also has confidence in this strategy. "An efficient production process is the basis for sustained improvements," he says. "Every megawatt, every tonne of steam that isn't used is a tonne that doesn't need to be produced. These improvements allow us to align the energy generation and transformation processes more accurately and, by achieving a higher utilisation rate, to produce the energy required for the core process more cost effectively."

Modern recovery boilers, such as those used at our paper mill in ?wiecie, make this possible. Black liquor, a by-product of pulp production, contains substances including lignin, sugar and inorganic salts that have been dissolved from the fibres as well as the process chemicals. This liquid biomass is boiled down and subsequently burned in the recovery boiler.

The recovery boiler effectively recovers the process chemicals, while the energy generated by this process is contained in high-pressure steam. Using this steam to drive steam turbines reduces the pressure, making the steam suitable for use in the process and converting the excess energy into electrical power.

Although recovery boilers have been used in the paper industry since the 1950s, it is only in recent years that the technology has become sufficiently advanced to allow industry to make considerable savings and develop sustainable, environmentally-friendly production processes. The old recovery boiler at Mondi ?wiecie in Poland reached steam temperatures of around 440° C, whereas the new boiler is able to achieve temperatures of around 505° C, for example.

"As a result, the electrical energy yield has almost doubled with only a slightly larger volume of black liquor," says Zlabinger. Rather than being decommissioned, the old recovery boiler has been converted into a biomass boiler that utilises the biogenic remains from wood preparation in the mill.

Energy efficiency allows energy to be decoupled

Heat decoupling plays an important role at many of our sites. Our paper mill in Syktyvkar, Russia, heats around 60,000 private households. In ?wiecie, Poland, this figure is 10,000 households, while in Frantschach, Austria, the public utility uses heat supplied by the paper mill to heat the local football pitch.

Zlabinger explains, "In thermal terms, one household is not much for a mill: one house consumes around five to seven kilowatts in winter, while the output of a recovery boiler at Mondi is up to 700,000 kilowatts. The internal energy turnover in a pulp and paper mill is enormous, and therefore it is important to keep this energy efficiently in circulation, and not lose it."

Supplying heat and electricity is thus a positive side effect of an efficiently managed pulp production process. This is a key advantage of the paper industry compared to other energy-intensive industries: the raw material wood is used in its entirety – both its material and its energy content.

Flexible biomass-based electricity from the paper mill: Mondi as an electricity grid stabiliser

A pulp mill with a modern recovery boiler, such as ?wiecie in Poland, can generate up to 100 kilowatt hours of excess electricity per tonne of pulp. This excess can be fed into the power grid, allowing us to participate in the electricity balancing market. This market helps stabilise the power grid across Europe by balancing out fluctuations in demand and generation.

Across Europe, the proportion of renewable energy resources is significantly increasing, leading to fluctuations and bottlenecks. Mondi is an active participant in Europe's electricity balancing market in Poland, the Czech Republic, Slovakia, and especially in Germany and Austria.

Flexible power generation is vital for participants in the electricity balancing market. We can variably supply power to the grid or draw power from the grid. "We actively control our mills so that we can react flexibly, feeding in more power when the grid needs electricity, and less when the grid is oversupplied," says Stadler.

Consequently, we help balance electricity generation and consumption within the grid at several levels, supporting the further growth of renewables in Europe. "The renewable resources being expanded in Europe are chiefly wind and solar power, both characterised by their high degree of volatility," explains Stadler. That creates a demand for flexibility, which we help fulfil.

However, grid stabilisation is also a cost issue. As fluctuations in the power grids become ever greater in magnitude, grid stability becomes increasingly expensive to achieve, because it is often the highly cost-intensive, gas-fired power stations that provide this stability.

With the active participation of paper manufacturers, the overall costs can be reduced for everyone. In Stadler's eyes, this is clearly a win-win situation. Furthermore, Mondi is one of the few participants able to provide this stability using biomass-based renewable sources.

One of the few industries to have successfully decarbonised

According to Stadler, of the CO2-intensive industries within the EU, it is the paper industry that has decarbonised most successfully. "In terms of CO2 volumes per tonne of product, we have hugely improved our footprint; in this we are certainly unique. We actively help achieve the Paris Agreement goals, making us an industry that has taken on a pioneering role," he adds.

In the future, the world will continue its efforts to reduce CO2 emissions in energy generation and increase the contribution made by wind, solar and other renewables. Energy grids need to be able to react flexibly. We support this trend with our mills, which actively help stabilise local power grids.

According to Stadler, although global, these energy sector megatrends will have the greatest impact in Europe. With our new recovery boilers, which increase the proportion of renewable resources while at the same time raising overall efficiency, Mondi is well prepared for this future – demonstrating that sustainability is always good business.

Source: Mondi Group

 
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