Biomass is at home in Czechia

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Kněžice and Kutna Hora – 2 outstanding projects

Biomass is at home in Czechia

In the small municipality of Kněžice, Czechia, there is 1 biogas plant and 1 heating plant for straw and woodchips, in operation since 2006. As compared to pre-2006, when heating was based off coal, air quality is today much improved. Heat is delivered to individual homes and businesses at about 44 euros/mWh. The biogas plant uses food waste and residues such as agrobiomass and feed residue. The heating plant uses biomass from roadside maintenance and forestry management, as well as straw.

Located around 80 km from Prague, the town is energy self-sufficient thanks to a bioenergy facility, which consists of a biogas plant with CHP (330 kWel and 400 kWth) and a biomass heating plant (boilers 800+400 kW). The technology supplies the population with more than 90% heat and produces significantly more electricity than the village consumes, so that electricity can be sold. Additionally, the use of biogas units solves the problem in Knežice of organic waste processing. The centre operated by the municipality also produces pellets for heating houses in the neighbouring area

Source: https://www.100-percent.org/knezice-czech-republic/  

A self-sufficient town

The initiator and investor of the whole project is the municipality of Kněžice. Most of the funding for the project came from EU financial support schemes, a smaller part consisted of a loan from the bank and from the State Environmental Fund. The investment cost of this project was CZK 117 million (around 5 million Euro), without VAT, and has 123 connection points. This project is comparable to some of the far more intense investments in the Czech energy sector.

The total investment consisted in the construction of: (i) biogas stations with a cogeneration unit; (ii) wood waste incineration plants; and (iii) heat conduit from pre-insulated pipelines around the town. The latter will transport to almost every home in the town the heating and domestic hot water, coming from the boiler room and from the biogas plant throughout the year.

The boiler room mainly burns grain, linseed straw and energy sorrel in giant packs as well as small wood waste. It then delivers heat to the central heating system (CHP). Ash from wood and straw burning is used as a fertilizer for agricultural land. The boilers are in operation only during the heating period, when the excess heat from the biogas station is not enough to cover the heat demand in the CHP system. Mainly organic waste from a local farm, livestock manure, as well as bad and old biomass (silage, grass, grain, etc.) serve as an entry to the biogas plant. The station further elaborates and ecologically eliminates the sober content of the septic tanks and cesspools from Kněžice and its surroundings.

The Benefits

The benefits of the Kněžice project are twofold: firstly, they lie in saving of fossil fuels and the reduction of harmful emissions in the municipality. Secondly, the amount of electricity produced by the cogeneration unit in Kněžice will not be produced in Czech coal power plants. Overall, about 11 000 tons of CO2 emissions will be saved per year. One-year financial benefit for the municipality as a heating plant operator will be about 4.2 million CZK (166 000 euro). Therefore, despite the relatively high purchase price of electricity from a biogas plant and considering the payment of the loan, the return on investment will occur in about 15 years.

Source: CZ-Knezice.pdf (renewables-networking.eu)

Kutna Hora – A community united for its own energy

In a UNESCO city, Kutna Hora, a CHP plant heats buildings with straw and hay at 50euros/mWh from the surrounding countryside. The plant is housed on the premises of an old steel plant.

- - The private company operates its own CHP on grass biomass and provides heat supply services.
  - The electric capacity of the CHP is 23 MW.
  - The source of energy is grain and rapeseed straw and purposefully grown energy crops.
  - The annual consumption of straw is 55 thousand tons.
  - As a rule, the supply of raw materials is carried out at a distance of up to 50 km from the power plant. The company has a long-term contract for 10 years and provides straw harvesting services for its partners. The company offers for fuel suppliers the opportunity to take a certified ash-based fertilizer after combustion.

Source: https://uabio.org/en/news/9019/

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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