Small scale district heating facilities generate green electricity in southeast Sweden

Combined Heat and Power (CHP) technologies based on biomass combustion have great potential to reduce CO2 emissions because they use renewable energy sources, such as wood fuels or sawdust. Typical fields of application for biomass CHP plants are wood processing industries, sawmills, district heating systems and industries with a high process heat and cooling demand. In order for CHP plants to operate in a way that is economically and ecologically beneficial, both the electricity and the heat produced must be used.

CHP technology is already available in Swedish and European markets. Due to the high installation costs, and a lack of information about its efficiency, the technology is, however, currently not widely used in small-scale plants. Extensive research has been undertaken to illustrate the vast environmental potential of CHP technology but a larger initiative that looks at increasing market application is still needed.

In Sweden, nearly all district heating is biomass-based. However, not all plants generate both heat and power. Today, there are around 300 district heating plants (<10 MWheat) that only produce heat. With new technology for small-scale combined heat and power (CHP), bio-based electricity generation could increase by 2-9 TWh (2-7 % of total electricity demand in Sweden).

This project will demonstrate different small-scale biomass CHP technologies. The aim is to pave the way for a broader application of biomass CHP technology. The knowledge gained will be disseminated on a regional, national and European level. There are three main objectives:

1. demonstrate the technologies at small-scale biomass-based CHP plants that will be built in in Southeast Sweden;
2. promote the use of, and a business model for, small-scale biomass-based CHP technology at the regional, national and Europe level; and
3. increase the production of renewable electricity by promoting local small-scale biomass-based electricity production.

3 techniques are available for the demonstration of bio-based small-scale CHP  generation. The new technologies have the potential for increasing the total production of green electricity from biomass by 2-7% for all of Sweden. One of the promising technology for small-scale CHP is an organic rankine cycle (ORC) technology, which uses a closed turbine system with an organic medium with a boiling point below water.

The electricity is generated by using hot water from the boiler and cold return water. This technology is demonstrated at Ronneby municipality in southeast Sweden. The demonstration is performed within the EU project Life+ Small Scale CHP from Biomass (2014-2019). A gasifier at a dairy and a wet steam technology at a district heating plant is also part of the project.

The project has among its expected results, greater knowledge about the environmental performance of biomass-based CHP technology and increased use of biomass as a renewable fuel.