Demonstration plant gasifier in Hultsfred - Emå Dairy


Emåmejeriet (Emå Dairy) is a local producer of milk and dairy products in Hultsfred. The plant is owned and run by the farmers themselves.



From oil to woodchips

Milk from your home area” is Emå Dairy’s slogan. The milk is collected from the local farms Hagelsrum, Virstad, Fröreda, Torsjö Säteri and Ålatorp, which gives short transports and thus less environmental impact. Producing its own electricity and heat from local biofuels is entirely in Emå Dairy’s line with a focus on locally produced goods. The fact that Emå Dairy has replaced its oil-based heating system is partly due to reduced tax relief for the manufacturing industry, partly to the ambition to meet consumers’ increased environmental awareness, but also to the fact that the existing heating system was in great need of redevelopment.


Emå Dairy in Hultsfred has built a gasification plant where wood chips are converted into heat and electricity

In gasification plants, gas is formed via incomplete combustion of organic materials. The wood chips are fed to the top of the reactor and then move gradually downwards with the help of gravity, after which it is consumed. Due to a lack of oxygen, a partial / incomplete combustion of the fuel takes place and gas is formed. The hot gas that is formed is energy-rich and combustible and can thus be used both to extract heat and to drive an ordinary internal combustion engine.


The gas is led to an internal combustion engine which is connected to an electric generator. It transforms the mechanical work into electric energy that can either be used within the company or sold to the electricity grid. 


The residual product biochar can be used to bind nutrients and provide more efficient agriculture that does then not need additional fertilizer. A gasification process gives a high electricity yield, between 20 and 30%. At the plant in Hultsfred, the electricity yield is 23%.

Combined dryer and fuel storage

Fuel availability is a very important parameter when the carburetor works optimally with a coarse fractionated and dry fuel, which are in relatively limited supply in the area.

The solution to this problem was to construct a combined dryer and fuel 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.




Lessons learned

A dry and homogeneous fuel is needed for a gasifier to function optimally. One of the lessons learned from the gasifier at Emå Dairy is that the excess energy created inside the gasifier chassis is sufficient to dry incoming fuel to the gasifier down to the desired moisture content, which is below 15%.


The results also show that a gasifier works best with an even heat production and an installation is therefore best suited for an operator with an even surface at a relatively low temperature, for heating buildings. At Emå Dairy, the heating system was supplemented with an accumulator tank to even out the heat demand, which can also be done in other places with fluctuating heat demand.


The daily maintenance of a gasifier powered by wood chips is important. The maintenance mainly consists of ash emptying, changing the oil in the engine and one general check of the system. Our conclusion based on the experience of Emå Dairy, and in discussion with other suppliers of gasifiers, is that a service person is required who has several gasifiers to handle and who has the opportunity to keep a spare stock.


If the right conditions are given to a gasifier, with dedicated staff, a gasifier will have a payback period of around 10 years with the current electricity prices in Sweden. With a higher electricity price, the repayment period can be shortened for another couple of years.


For the gasifier to become commercially viable, it is required that some conditions are met, such as higher electricity prices and lower prices for biomass.


Calculations within the project show that a gasifier can have a payback period of about 10 years already with today’s energy prices.


The current tax limit (2020) on biopower also affects the profitability of installations around 50 kW.


Plant data gasifier


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

Max 312 MWh / year

Approximately 10 years


4.8 mm X 1.3 m X 2.5 m

Approximately 500 liters / week (about 1-2% by outgoing fuel)

CO (carbon monoxide) 25%

H2 (hydrogen) 17%

CO2 (Carbon dioxide) 8%

CH4 (Methane) 2.5%

N2 (Nitrogen) 47.5%



Max 6 000H

Approximately 4 million

Roughly fractioned chips

Volter ™ 40 Indoor

4.5 tons

Automatic ash handling

5.75 MJ / m

Gasifiers and manufacturers

Gasifiers general

In gasifier units, wood gas is formed by incomplete combustion of organic materials. Organic refers to carbonaceous material from living or dead organisms. There are different types of gasifying techniques. For the generation of heat and power, so called fixed bed gasifiers, where the fuel bed lies on a grate, are usually used. The solid organic fuel is feed at the top of the reactor, then moving downwards due to gravity as it is being consumed. Because of oxygen deficit, the fuel is only partially/incompletely combusted and wood gas forms. This gas mainly consists of carbon monoxide, hydrogen, methane and carbon dioxide. It is dangerous to inhale carbon monoxide since it easily binds to the red blood cells, thereby preventing oxygen from being transported into the body. However, at a later stage in the unit, the carbon monoxide is transformed into harmless carbon dioxide by combustion.

In a downdraft gasifier, the gas is extracted at the bottom of the reactor, whereas it is extracted at the top in an updraft gasifier. In the latter case, air is led in at the very bottom, whereas it is supplied higher up in the reactor in a downdraft gasifier. Updraft gasifiers form more tar, but can handle more moisture in the fuel than downdraft gasifiers, since the produced gas passes the incoming fuel and dries it. One other difference between the two principles, is that the gas from a downdraft gasifier has a higher temperature than the gas coming from an updraft gasifier.

The hot gas that forms is full of energy and combustible, thereby possible to use for extraction of heat as well as for running a conventional combustion engine. The heat is obtained thru one or several heat exchangers. The thermal energy is used for heating of estates and tap water, in industrial processes etc. The wood gas is then directed to a combustion engine, where the chemical energy is transformed to mechanical work. The shaft of the engine is connected to an electrical generator, transforming the mechanical work to electrical energy that can be either used in your own business or sold on the grid.


                                                                                                                                                                                                                                                                                                                                                                                               Gasifier and filter.


All Power Labs
American company focusing on biomass gasifiers for production of electricity, also offering heat exchangers as compliment for a complete small-scale CHP installation (15 kWel). Several installations can run in parallel. Has several reference installations, where the gasifier feeds an isolated micro grid, i.e. with no connection to an external grid. Possible application in Sweden could be a remote tourism facility without grid connection. One reference example is an island, where diesel generators have been replaced by a mix of renewable energy sources such as wind and solar power as well as a gasifier. It is also possible to connect the gasifiers to the national grid.
Spanner Re2
German company with products within two segment, production of heat from biomass and combined heat and power production from wood chips. Have both stand-alone gasifiers and those integrated in containers, available in different sizes ranging from 9 kWel to 450 kWel. Several gasifiers can run in parallel in case of higher heat demand.
The company also delivers automatic dryers and fuel handling systems for the wood chips as well as ash removal systems. Many reference installations, for instance a manufacturer of parquet floors using residues from the production as fuel to the gasifier. The heat is used for drying the wood used in the production of floors and for heating the facilities and the produced electrical power is sold on the national grid.
Finnish company manufacturing complete gasifier modules for combined heat and power production using wood chips, 40 kWel/100 kWheat. Several units can run in parallel in case of higher heat demand. The company also sells drying units for wood chips.
There are several reference installations, for instance a recreation facility selling its excess power to the national grid, but that is also able to run their internal grid independently, i.e. disconnected from the external grid. The heat is distributed in a local district heating system. 


Comparison - gasifiers

Download spreadsheet

Manufacturer All Power Labs Spanner Volter
Product identifier PP20 Power Pallet  HKA 45 (other alternatives available) Volter 40 Indoor
Automation yes yes yes
Thermal output 20 kW 102 kW 100 kW
Electrical output 15 kW 45 kW 40 kW
Sound level @30 fot/9,14 m 85 dB(A) information not available information not available
Feedstock consumption 1,2 kg/kWhel 40,5 kg/h (0,9 kg/kWhel) 38kg/h (0,95 kg/kWhel)
Automated fuel supply 3 h per hopper fill, automated filling of hopper available as option available as option available as option
Approved feedstock wood chips, nut shells, corn cobs wood chips wood chips
Feedstock size 12-40 mm max. 30% <4 mm <63mm: >80% 16-50mm, >60% 30-50mm, ≤9% 50-63mm, ≤1% <3,2mm
Moisture content feedstock 10-30% max 13% <18%, optimum <15%
Type of gasifier downdraft downdraft downdraft
Automated ash removal yes available as option yes
Engine GM Vortec 3,0 liter information not available Agco Sisu Power 8,4L, 6-cyl.
Generator Mecc Alte NPE32 information not available ABB M2BA 225 SMB 4, 45 kW
Heat exchanger optional, one step information not available three steps
Total efficiency 35% information not available information not available
Electrical efficiency 20% information not available information not available
Thermal efficiency information not available information not available
information not available

News about the gasifier in Hultsfred

Information about small scale chp technologies on the Svebio conference


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.





Along with a private person, Emå dairy share the Hultsfred Municipality environmental award for 2015. Emå dairy got awarded for investing in a micro-carburetor and thus replacing the fossil oil boiler that supplied the dairy with electricity and heat. Congratulations Emå dairy!

Energy Cities


Small Scale CHP Life+ in the Energy Cities blog. To the article.

The gasifier inaugurated at Emå dairy


Opening ceremony at Emå dairy. The vice president of Hultsfred municipal executive board and the environmental manager of the county administrative board were there to cut the ribbons. The assembled guests and media were  introduced to the facility and treated to Finnish pasties as homage to the company who constructed the gasifier. 

Plants for small-scale Combined Heat and Power production are built in Southeast Sweden for demonstration of techniques. Project runs from July 2014–December 2019.
Partners:Emå Dairy and Ronneby Miljö & Teknik AB with support from EU financial instrument Life+, Swedish Energy Agency and Energiföretagen Sverige.