Small-scale biomass-based cogeneration: different techniques being tested in South East Sweden


Publication date

April 29, 2016

Energy Cities member, the Energy Agency for South East Sweden, is currently involved in the testing of three different techniques for small-scale biomass-based cogeneration (gasifier, wet steam turbine and organic Rancine cycle) which are being built and demonstrated in South East Sweden as part of the project Small Scale CHP LIFE+ (2014-2018).

For smaller industries, real estate or farming, a biomass gasifier which produces both electricity and heat can be an alternative to replace an oil boiler.

Of the three different CHP techniques, the gasifier is up and running. Emåmejeriet (Emå Dairy) is a local producer of milk and dairy products in Hultsfred, Småland. They have installed a gasification plant where the wood is converted into heat and electricity.

Plant data gasifier Emå Dairy

MODEL – Volter ™ 40 Indoor

WEIGHT – 4.5 tons

DIMENSIONS – 4.8 mm X 1.3 m X 2.5 m

EFFECT – 40 kW of electricity (45 kW) generator and 100 kW heat

Operating hours / year – Max 7 800H

ELECTRICITY – Max 312 MWh / year

INVESTMENT COST – Approximately 3 million

CALCULATED REPAYMENT – Approximately 8-10 years

RAW MATERIAL – Roughly fractioned wood chipping


By replacing the old oil boiler with a micro scale power plant in the form of a thermal gasifier, Emå dairy will become virtually self-sufficient in heat. In addition, local electricity will be produced, covering about 20% of the electricity demands. A thermal gasifier provides high electrical efficiency, good controllability and a reasonable investment.
An accumulation tank will manage the shifting heating requirements during the day. The demands for a high flow temperature of the heat were such that there was only one supplier that could guarantee the specifications necessary for the production of heat to the Emå dairy. Feedstock availability is a very important parameter when the gasifier works optimally with a coarse fractionated and dry feedstock (wood chipping), which are in relatively limited supply in the area.

The solution to this problem was to construct a combined dryer and feedstock storage based on demountable containers for flexibility and scalability. One factor that made the dryer economic is that the model Volter ™ has a ventilation connection for low-temperature waste heat, which makes it easy to use low-grade heat for drying. This combined dryer and feedstock storage is unique in it’s case.

Why not go a study visit and learn about their experiences? 
The dryer and the installement of the gasifier Volter are unique, since the facility is connected to an industry which has a variation in the heat demand and requires a relatively high flow line temperature.
If you are planning a visit to Sweden, why not take the opportunity to learn more about small scale combined heat and power production by visiting Emå Dairy? 
The dairy plant is open for study visits for anyone who wishes to know more about small-scale production of heat and power. The wet steam turbine is currently under construction in Ronneby, Blekinge, and will be open for study visits from fall 2016.

To book a study visit and learn more about the project, visit the website of the South East Sweden Energy Agency. You can of course make all the traveling arrangements yourself, and just check the date with them. But if you wish, they can also make a bundle arrangement for you, including lunch and other visits of your choice.

Combined Heat and Power (CHP) technologies based on biomass combustion/gasification 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.
Large scale CHP technology is already available on 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 small scale CHP technology, but a larger initiative that looks at increasing market application is still needed.

Further information:
Daniella Johansson, Project Manager
Tel. +46 76-86 17 000, 

Johanna Wallin, Communications officer
Tel. +46 709 – 21 60 56,