The transition of the energy system towards lower greenhouse gas emissions requires new solutions to electrify heat-producing power plants and to store electricity generated from renewable energy sources more cost-effectively, even at a large scale. In the BitKein research project coordinated by VTT, unique research environments were built in which a power plant boiler is heated with electric heating elements and solar electricity is stored in a flow battery. The results show that flexible use of electricity can reduce fuel consumption and emissions while improving the flexibility and self-sufficiency of the energy system.
Electrification of power plant boilers brings flexibility and reduces emissions
The BitKein project implemented a pilot-scale experiment in which electric heating elements connected to a fluidized bed boiler generated heat instead of fuel. By utilising electric heating, the fuel consumption of a power plant can be reduced when electricity is available at low cost and in large quantities. Compared to a separate electric boiler investment, integration also extends the lifetime of the existing boiler, as temperature fluctuations are reduced. When the boiler was electrically heated, the temperature level required for complete combustion (no CO emissions) was achieved at minimum load with a smaller amount of biomass.
System-level modelling showed that the economic feasibility of the electric heating solution depends on the level of electrification in the system and the price of electricity. “Modelling confirmed that flexible electricity use at the power plant can improve the overall economic performance of the system, reduce fuel consumption and carbon dioxide emissions – particularly in partially and non-electrified district heating systems – and increase the flexibility of energy production in situations where renewable energy sources and available waste heat vary”, says Timo Leino, Senior Scientist at VTT.
Flow battery enables storage of solar energy and new use cases
As another key achievement of the project, a container-scale flow battery system was acquired and commissioned at VTT and connected to a wall-integrated solar PV system. A flow battery is an electrochemical energy storage system in which energy is stored in a liquid electrolyte. Charging and discharging are based on redox reactions.
The vanadium redox flow battery-based solar PV system implemented in the BitKein project, together with its data acquisition solution, is unique in Finland and provides an environment for research and development of both storage methods and materials, as well as for optimising energy use in different situations. In the first test series, the overall system efficiency exceeded 60% and can reach up to 67%. Increasing the storage scale appears to improve its profitability, and systems of several MWh’s are already a reality.
In the project, the use of the flow battery in various applications and electricity market situations was simulated using dynamic modelling and optimisation. Energy storage systems can significantly improve energy self-sufficiency and potentially also the reliability of critical systems, for example in buildings, but storing only a building’s own solar electricity did not prove to be economically viable at current prices.
Instead, versatile use such as participation in reserve markets and combined battery systems serving multiple buildings, could significantly shorten the payback period of the battery investment, especially in large-scale applications and when operating simultaneously in several reserve markets. With the acquired research equipment, control logic can be gradually improved, and for example, balancing market data can be integrated into the system, bringing the technology closer to practical applications.
Materials development supports further development of flow batteries
At the Department of Chemistry of the University of Jyväskylä, methods were developed in the project to replace fossil-based graphite electrodes in flow batteries with biomass-based carbon material (so-called biographite), and these new electrodes were tested in a laboratory-scale flow battery environment.
As part of the materials research, the university also sought more cost-effective proton-exchange membranes to replace the currently used expensive fluoropolymer membranes, in order to maximise the benefits of bio-based electrodes. Initial tests confirmed the functionality and promising potential of bio-based electrode materials, but further development and solutions to scaling challenges are needed to improve their performance and durability.
The materials expertise generated by the University of Jyväskylä complemented the BitKein project and laid the foundation for new types of cost-effective energy storage solutions needed as the energy transition progresses.
Project research environments will continue to support electrification and energy storage
The new research and testing environments built during the BitKein project will continue to support development work after the project ends. The electrified boiler pilot provides a platform for further research into how power plant processes can be electrified and operated more flexibly. At the same time, the flow battery environment offers data and operational experience that help model the performance and role of large-scale batteries in balancing electricity production and consumption.
These innovations respond to the current need of industry and society to reduce emissions and increase the flexibility of the energy system, especially as solar and wind power production is expected to grow rapidly. The results of the BitKein project provide guidelines on how industry and energy companies could better utilise low-cost renewable electricity in the future, for example in district heating production and energy storage, while improving self-sufficiency, supporting security of supply objectives, and reducing greenhouse gas emissions.
Further information:
VTT: Timo Leino, Senior Scientist, [email protected], +358407579493
VTT: Janne Kärki, Research Team Leader, [email protected], +358407510053
University of Jyväskylä: Matti Haukka, Professor, [email protected], +358040805466
BitKein is a joint project of VTT and the University of Jyväskylä, with VTT responsible for the main project.
Project duration: 1 September 2023 – 31 May 2026
Total budget: €826,107
The Regional Council of Central Finland has granted EU funding of €646,484 for the project.
The project is co-funded by Alva-yhtiöt Oy, Vantaan Energia Oy, Lahti Energia Oy, Savon Voima Oyj, Kuopion Energia Oy, Kokkolan Energia Oy, Kainuun Voima Oy, Metsä Group Oyj, Elisa Oyj, Sumitomo SHI FW Energia Oy, New Stars & Company Oy, FinnVolt Oy and Sähköäijät Oy.
