The district heating plant in Bräkne-Hoby is operated by Ronneby Environment & Technology AB. They have installed an ORC plant, a technology for small scale CHP. Through the possibility of producing renewable electricity in the existing district heating plant, the plant becomes less dependent on external electricity.
In Bräkne-Hoby, Ronneby Environment & Technology AB have installed an ORC (Organic Rankine Cycle) in the existing biofuel boiler.
The ORC does not produce heat itself. The ORC technology is based on a closed turbine circuit powered by an organic working medium with a boiling point lower than water. The plant generates electricity by using the hot side of the boiler circuit and the cold side of the district heating network.
Via the circuit’s evaporation medium (with a low boiling point), the ORC system can generate electricity at a lower temperature than ordinary cogeneration plants. This makes the technology well suited for the production of green electricity from biomass at smaller district heating or local heating plants. However, by working with small tempertature differences, the ORC has a limited power exchange.
The total energy efficiency of the ORC is high. About 10 % of the electricity produced is used to drive the pump that raises the pressure of the coolant in the turbine circuit.
In the pilot plant in BräkneHoby, the electricity efficiency has turned out to be around 2%. Electricity production depends on the temperature difference between the hot flow temperature from the boiler and the temperature of the return on the district heating water. The higher the temperature difference, the higher the electricity production. In Ronneby, the supply temperature is relatively low. In another system with better conditions, more electricity can be produced.
Availability has been high and operational disruptions have been few. However, the system needs a daily inspection of about 15 minutes and it needs to be refilled with oil 2-3 times a month.
49 kW electricity
Circa 231 MWh
Circa 10-14 years
MOISTURE IN RAW MATERIAL
2,5 x 1,14 x 2 meters
4 700 h
Circa 1,7 million SEK
Wood chips, forest residue, bark etc.
ORC and manufacturers
An Organic Rankine Cycle (ORC) is a thermodynamic cycle that converts heat into mechanical energy, which in turn can be converted into electricity. Thermodynamics is a part of physics relating to heat and temperature and their relation to energy and work. Cycle means that the system returns to its original state after a series of processes, the thermodynamic processes go thru a cycle that begins and ends in the same state.
Heat is supplied to a closed circuit from the outside. The heat may come from nuclear power or combustion of biomass, oil or coal. The working medium in the closed circuit is vaporized in an evaporator, expands in a turbine or screw expander, condenses in a condenser and is pumped back to the evaporator. Thereby the cycle is closed and the working medium is back in the original state. As the working medium expands, a transition to mechanical energy takes place and rotates a turbine or screw expander. This work is transformed to electrical energy by a generator.
Most commonly, water is used as working medium, when generating electricity. Instead of water, ORC uses an organic working medium such as pentane, butane or toluene. The finesse is that, with an organic medium with a lower evaporation temperature than water, the steam process can operate at a lower temperature without the risk of getting damp vapor, which implies a risk of corrosion in turbine or expander. Since the temperature differences are smaller in ORC plants than in traditional steam cycles, the efficiency is lower. On the other hand, even low-temperature heat sources can be used.
The ORC in Bräkne-Hoby.
|Opcon Energy System
Swedish company developing techniques for small scale production of electricity from waste heat. Hot water in a district heating plant and industrial process water can be used for the generation of electricity.
A Swedish reference site is a company, which is now able to utilize waste water from their process for production of electricity. As a bonus, they are also able to preheat their process water.
Swedish company with a self-developed turbine, which is capable of producing electricity with incoming temperatures down to 90°C. Delivers complete systems in modules.
No reference site presented on the company website. For more information and possibilities for study visits at an installed unit, please contact the project Small scale combined heat and power.
Italian company developing ORC technique since 1980. Has systems that can utilize heat from boilers, waste water, solar collectors etc.
Has many installations in Europe, but very sparse information about them on their website.
News about the ORC in Bräkne-Hoby
We see some happy results in this project! The two Swedish companies Örkeljunga district heating plant and Solör Bioenergi (both having visited the ORC plant in Bräkne-Hoby during autumn and spring) have announced that they have invested in an ORC plant of their own. The two new installations marks the sixth and seventh ORC plant by Againity in Sweden so far!
During May 8, together with Ronneby Miljöteknik, we organized a seminar about the possibilities with our largest green source, the forest!
30 people from energy companies in Blekinge and Småland, politicians from both blocks, county administrative board, forest management and companies in the bioenergy industry gathered to listen and to discuss the bioenergy's obstacles, opportunities and potential. The participant engaged actively in during the day, ending with a panel discussion for input to the energy and climate strategy of Blekinge county. In conclusion, participants also gave input to what they want to see as an activity in the bioenergy area in the future. All participants agreed that the most important thing in the future is cooperation and more activities for cooperation. That way bioenergy can become a bigger part and play a greater role in the energy and climate strategy!
On April 25, Arne Andersson at Ronneby Miljöteknik and Daniella Johansson were invited to Energiföretagen Sverige to talk about the theme: "Is microproduction passable to cogeneration?". 50 people got to see the first results of the first season of small-scale electricity production in BräkneHoby. And the answer to the question was: Yes, but it's more profitable under certain conditions!
On March 26, about ten people from energy companies, manufacturing companies and consultants visited the Sörby plant and Bräkne-Hoby facilities to learn more about small-scale chp.
14- 15 of November, project manager Daniella Johansson participated on the Svebio grand biopower and heat conference in Sandviken. The conference began with a study visit to one of the biggest bio power plants in Sweden, co-owned by BillerudKorsnäs and Gävle Energi.
During the conference many topics were discussed, among them the latest news of the climate negotiations in the EU regarding solid biomass and the pellets market in Sweden.
During the second day of the conference, Daniella Johansson moderated a discussion of small-scale cogeneration. A new study on the potential for small-scale cogeneration and various suppliers with new technologies was presented.
The ORC unit was officially inaugurated on 31st of May. 30 people attended the ceremony that was held by Bengt Holm, chairman of the board for Ronneby Environment & Technology.
The ORC is now setup and running at the district heating plant in Bräkne-Hoby. The very first study visit was made on Friday.
The preparations are made for the upcoming installation of the organic Rankine cycle (ORC) at the district heating plant in Bräkne-Hoby. The ORC is expected to be delivered during week 9.
The ORC will be put on the cleared floor space where the ladder is. The ORC will be connected to the cut pipes on the upper right.
An ORC in progress in Bräkne-Hoby
On September 12th, a supply agreement between Ronneby CleanTech Energy AB and Againity AB was signed for the delivery of an ORC plant to Bräkne-Hoby in Blekinge.
Photo: Anders Adolfsson, Energy Agency for Southeast Sweden.
Ronneby Miljö & Teknik AB is planning for an Organic Rankine Cycle in a thermal power station in BräkneHoby. The procurement of the ORC is currently in process.
Partners: Emå dairy and Ronneby Miljö & Teknik AB with support from EU financial instrument Life+, Swedish Energy Agency and Energiföretagen Sverige.