Clean Heating with Biomass

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This year, the city of Dzierżoniów (South – West Poland) began the transition to clean energy with the operation of a new biomass heating station. Established by Zakład Energetyki Cieplnej (ZEC), the installation replaces an old coal burning site and supplies clean heat for over 20,000 citizens.

In the city of Dzierżoniów, 100% of the current heat supply is produced in coal, dust-fired boilers. Supplied through the district heating network of 250 heat centers, the largest recipients are residential housing estates, public utility institutions, shops and the municipal hospital. The contracted power currently stands at 29 MW and has great capacity for further growth. A continuous investment process has been carried out since the purchase of the heating system by the new owner ZEC, and the process of abolition of individual gas stoves and the subsequent replacement with district heating remains ongoing.

In 2016, a decision was made to build a biomass-fired, high-efficiency cogeneration installation. An application was submitted for co-financing in the name of high-efficiency cogeneration as part of the plan to decrease emissions of the economy under the Infrastructure and Environment 2014 – 2020 Operational Program. Construction began in 2018 and involved the abolition of 4 WLM5 coal dust boilers and the preparation of foundations of new installations. The new wood chips boilers that came in their place had a total power of 6.05 MW.

The installation is environmentally friendly, with dust emissions being reduced by 20 times compared to the fine, coal-fired boilers that previously supplied the area with heat (from 100mg/Nm3 to 5mg/M3). Furthermore, the NOx emissions have also been reduced through the use of a SNCR denitrification system. Electricity is generated by a turbo generator manufactured by TURBODEN, a well-known and respected producer of ORC generators in Europe.

The installation launched in 2020, largely as a trial run. Thanks to its success, heat and electricity is now being produced from an ecological source. The entire investment has been planned in such a way as to avoid interruptions to the local heat supply. Investments in the plant are aimed at achieving an energy efficient heating system, to reduce the combustion of fine coal, and ultimately to end the production of heat and electricity from fossil fuels. The savings from the non-purchased CO2 emission allowances will support the continued development of the district heating system through its increased modernisation.

The prices of which have, however, recently soared to a level impossible to handle for companies like ZEC and notably, this is not the end of the price increases.

District heat generated in such modern installations – as well as the expansion and modernisation of the heating stock – allow for competition with local heat sources and significantly reduce greenhouse gas emissions and improve the natural environment in both the city of Dzierżoniów, and its surrounding areas.

About the campaign

The campaign is powered by Bioenergy Europe and relayed across Europe by both national and international partners supporting the belief that bioenergy is more than a renewable energy source, it is also a reliable path that will lead Europe to achieve its renewable energy transition in the shortest span of time.

Solid Biomass Conversion Processes

Logging, grinding, screening and drying operations are mechanical processes for enhancing solid biomass fuels. These operations help transform biomass into homogeneous fuel that is easy to handle, with a higher energy recovery (eg. woodchips, wood logs, agrofuel). In general, moisture content in woodchips used for energy generation in municipal or industrial plants ranges between 20-30%.

Densification is another popular way to transform woody material into an advanced fuel with high calorific value. This process involves compressing biomass and lowering moisture levels to a range of 8-10%, allowing for an homogenous fuel – either in the form of pellets or briquettes. The heat during compression fuses the lignin in the biomass, naturally binding the biomass together in a new, enhanced shape. Thanks to densification, the homogenous biomass fuel is easier to transport and can be used in automated biomass installations, such as pellet stoves and boilers.

Thermo-chemical conversions are now used to produce fuel with even higher calorific value, utilising torrefaction or steam explosion technologies. During the torrefaction process, wood is subjected to temperatures of 230°C-300°C at atmospheric pressure without oxygen. Comparable to some extent to coffee torrefaction, this method creates a fuel with unique characteristics. As compared to conventional wood, torrefied wood has very low (>5%) moisture content, is easily grindable and is relatively hydrophobic.

Thanks to advanced technologies, woody biomass can also produce liquid and gaseous fuels. Pyrolysis, for instance, is a thermal-chemical conversion that requires a high temperature (>400°C) and little oxygen to convert solid biomass into gas, liquid fuels (pyrolysis oil) and/or biochar. Gasification is another thermo-chemical conversion that takes place at high temperatures (>800°C), with limited oxygen and/or steam, and converts solid biomass into synthesis gas, known as syngas – which contains carbon and hydrogen and can be used to produce liquid fuels such as biodiesel.

Wet Biomass Conversion Processes

Wet biomass is present in high volume across Europe (manure, agricultural waste and by-products). As it contains too much moisture to be converted efficiently into energy via a direct combustion process, other conversion pathways and energy outputs have been developed by the biogas (eg. anaerobic digestion) and biofuel sectors (eg. fermentation). Anaerobic digestion and fermentation are the two main conversion pathways used for converting wet biomass feedstock into advanced fuel.

Anaerobic digestion is the microbiological process of decomposition of organic matter, in the absence of oxygen, and is common to many natural environments; it is largely applied today in order to produce biogas in airproof reactor tanks, commonly referred to as digesters. A wide range of micro-organisms are involved in the anaerobic process which has two main end products: biogas and digestate. Biogas is a combustible gas consisting of methane, carbon dioxide and small amounts of other gases and trace elements. Biogas can be used in direct combustion to produce heat, but also power if converted within a cogeneration plant or in adapted gas motors. Biogas can also be upgraded via purification processes to a biomethane that can be injected into the existing natural gas networks, used as a chemical product and/or vehicle fuel. Digestate is the decomposed substrate, rich in macro- and micro-nutrients and therefore suitable for use as plant fertiliser.

Fermentation is a biochemical conversion whereby microorganisms, including yeast and bacteria, convert matter into products such as ethanol and liquid transport fuel (biodiesel). This process is done in several stages. First, sugary and starchy feedstock such as corn must be crushed and combined with water, allowing enzymes to convert this starch into sugar. This ferments along with the addition of yeast and is distilled into bioethanol. Bioethanol can also be produced from cellulosic biomass, such as grass, wood and stalks, via fermentation; however, this process is more complex and involves a mechanical pre-treatment and the addition of enzymes, or the breakdown of the lignocellulose into sugar through hydrolysis, followed by the same procedure.

Solid bioenergy feedstock

Renewables represent 8,0% of EU-27 total energy consumption (22.473 kilotonnes of oil equivalent) in transportation, of which 68% is provided by biofuels in 2018. It is rather challenging to foresee how biofuels (in particular first-generation biofuels) will continue to develop, since recent EU legislation established a quota for these biofuels. EU statistics on renewables in transportation can also be misleading regarding the actual level of production, because multiple counting rules are applied in accordance with the EU renewable energy directive. Looking at it in more detail, the biofuel market is driven by biodiesel and bioethanol. Biodiesel was the first biofuel developed and used in the EU in the transport sector in the 1990s. EU-27 remains the world’s largest biodiesel producer and it consumed 13,303 Ktoe in 2018. By comparison, bioethanol consumption in 2018 reached 2,620 Ktoe for an actual production of 2,365 Ktoe (Biofuels Report, 2020).

Bioenergy comes in all shapes and sizes

Within our close environment, a great source of organic materials such as plants, algae, or organic wastes, can be valuable fuels as soon as a technology makes it possible to efficiently extract all of its energy potential. Bioenergy players traditionally refer to biomass to describe those usable feedstocks. Biomass currently used in Europe includes wood from forests, agricultural crops and residues, by-products from the wood and agricultural industry, herbaceous and woody energy crops, municipal organic wastes and manure, and could potentially integrate algae and marine biomass in the future.

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