Commentary by Jiří Kratochvil from UCED on one of the largest biomass heating plants
The energy sector faces a number of challenges. It must respond to climate change, work with modern technologies and new social realities. The pursuit of a greener and more climate-friendly energy sector will increase thanks to a higher share of renewables. Examples include biomass heating plants. One of the largest in the Czech Republic – EC Biowatt in Kutná Hora – is owned by the UCED group of the CREDITAS group.
In the above-mentioned plant, electricity and heat are obtained in a combined form from grain and rapeseed straw and hay. The operation there is divided into two power units. The unit with a steam boiler enables combined production of electricity and heat, while the unit with hot water boilers is used for production and supply of thermal energy. The unit has a total thermal output of 41.5 MW. Such a large unit can generally light over 26,000 households at an annual consumption of 2 MWh and heat over 4,000 households at an annual consumption of 25 GJ.
The UCED Group wants to further develop the site. The baling with a high-pressure baler takes place directly in the field. Bales 120 cm wide, 70–90 cm high and approximately 240 cm long are stored in such a way as to prevent degradation. They are delivered to the heating plant throughout the year. The fuel stored here is used within 4 days. Regular deliveries from suppliers’ warehouses, which are indispensable for the smooth operation of the heating plant, must therefore be ensured.
In the warehouse, the fuel is placed in stacks from which the bales are transported by a fully automatic overhead crane to the stacking table. The bales are then distributed into two chain conveyors, where the strings holding the bales together are cut and the entire bale is then split by vertical augers. The material thus crushed is transported to the boiler where the combustion process takes place. The combustion of pure biomass in the boiler produces steam. The produced steam drives a steam turbine with a generator and the resulting product is electricity. Heat supply is provided by hot-water boilers and a flue gas aftercooler using waste heat. Heat is supplied to end customers through the central heating supply system.
The residual product after biomass combustion is the certified organomineral fertiliser “fly ash”, which is very rich in minerals such as calcium, magnesium, potassium and phosphorus. Part of the burnt biomass is thus returned to nature in the form of agricultural compost. This is 3 to 5 percent of the original material.
Within a radius of several tens of kilometres from the heating plant, purpose-grown crops are processed to generate heat and electricity. Everything is produced ecologically, without waste. Fly ash is actually a product that has other uses. It is an economic, ecological resource that also supports regional business. In terms of categories for energy use, hay or straw falls into the category of combustion and gasification of clean biomass, referred to as O1.
New Energy Sector
Due to the development of the new energy sector, biomass heating plants will also be part of decentralised sources. The way to go about this is automated modern production. The aforementioned Kutná Hora heating plant will be connected to the technical and commercial control room. This will ensure remote control of operation and optimisation of production. Other power distribution systems of the aforementioned energy group are gradually being integrated into this system.
This text was published in the Energetika magazine, author: Jiří Kratochvil, COO of the UCED Group