Subsidies, taxes and duties on energy in Denmark

- the reasons behind the success for biomass in Denmark

In the spring of 1996, the Danish Ministry of Energy presented a new energy plan called "Energy 21". The goal of Energy 21 is to contribute to a sustainable development of the Danish society.

A wide range of subsidies, taxes and environmental legislations dominate the development of renewable energy in Denmark. Some results of this is a wide range of wind mills, solar heating systems, approx. 100 biomass fueled district heating systems and a large number of individual straw and wood fired boilers in private dwellings.

When the Centre for Biomass Technology hosts foreign visit groups a major question is always: How can you have so many plants and techniques in your small country?

The answer is: It pays off! And the reason that it pays off is the subsidies for investment and subsidies for electricity production, which improve the situation for biomass, and the taxes on fossil fuels, which make these more expensive.

Table of Contents


Subsidies to Energy Production based on Biomass

Subsidies to Private Dwellings

Subsidies to Decentralized CHP Plants

Taxes on Energy in Denmark

Energy Tax


Repayment of Energy Duties

Environmental Legislation




The Danish energy sector is dominated by a consumption of not renewable energy resources, and the emissions from the energy production result in a charging of the atmosphere and the environment in general. The goal of Energy 21 is to contribute to a radical reduction of the environmental problems caused by energy production.

This will be done by:

The Danish government is using different means to achieve the goals of Energy 21. Among these means are subsidies, duties and environmental legislations. These means are described in this text.

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Subsidies to energy production based on biomass

One of the main goals of Energy 21 is to reduce the emission of CO2 with 20% before year 2005 compared to level of CO2 emission in year 1988.

In order to achieve the goals in Energy 21, the Danish Energy Agency in 1996 has granted 128 million DDK, about 14 million pounds, to install energy devices which exploits renewable energy, as for instance straw and wood for heating in private homes. It is possible to get subsidy to a boiler up to 200 kW input thermal effect.

Subsidies to private dwellings

Among other things, as for instance solar heating, you can get a subsidy to a biomass boiler.

The subsidy to a biomass boiler varies from 10 to 30 percent of the investment, depending on efficiency and the emission of dust and CO. It is only possible to get a subsidy to a heating system where heat is distributed by water, so-called central heating systems. This means that you cannot get a subsidy to for instance a woodburning stove. Another condition imposed by the The Danish Energy Agency is, that the dwelling is sited outside areas with district heating.

For owners of houses with electrical heating, it is also possible to get a subsidy to convert to a central heating system. The standard subsidy is 5.000 DDK (550 £) plus 60 DDK (66 £) per m2 heated dwelling area. Furthermore, there is an extra subsidy if the electrical heating system is replaced by a system based on renewable energy. If the energy source is biomass, the extra subsidy is 40 DDK (4,4 £) per m2 heated dwelling area. A condition for achieving the extra 40 DDK, is that the biomass contributes with at least 90% of the energy required for heating.


The owner of a house on 140 m2 change from an electrical heating system to a wood chip fired boiler and a central heating system.


Central heating system (radiator, pipes,             30000 DDK        4800 $    

chimney                                              10000 DDK        1600 $    

wood chip boiler                                     40000 DDK        6400 $    

Total costs                                          80000 DDK        12800 $   


Standard subsidy                                     5000 DDK         800 $     

Subsidy due to changing from electrical heating      8400 DDK         1344 $    

Extra subsidy for changing to a biomass system       5600 DDK         896 $     

Subsidy to biomass boiler                            15000DDK         2400 $    

Total subsidy                                        34000 DDK        5440 $    

This means that the subsidy expressed in percentages for this operation is 43% of the costs.

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Subsidies to decentral CHP plants

With the purpose of reducing the emission of CO2, The Danish Energy Agency gives a subsidy of 10 øre (10 øre = 0,10 DKK 1,6 or ¢) per kWh electricity produced on a decentralized CHP plant.

If the decentralized CHP plant is fired the biomass, The Danish Energy Agency gives another subsidy of 17 øre (2,7 ¢) per kWh electricity produced. That means that there is a subsidy of 27 øre (4,3 ¢) per kWh electricity produced on a decentralized biomass fired CHP plant.

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Taxes on energy in Denmark

In January 1996, the "green taxes" took effort. The idea of the green taxes is - besides to collect taxes - an attempt to control the energy consumption and the energy production in a more sustainable direction. The taxes will come into force over a five year period and reach the final level in year 2000.

Energy tax

In Denmark, for many years energy has been imposed by a duty. Recently fossil fuels have been imposed by a CO2 duty, depending on the kind of fuel, in order to reduce the emission of CO2.

Due to the fact, that biomass is a CO2 neutral fuel, it is exempted from the CO2-duty.

For some of most obvious competitors to biomass the energy taxes are:

Tax per ton fuel           Energy tax          CO2-tax      

Fuel oil                1660 DKK / 266 $   320 DKK / 51 $   

Coal                    1040 DKK / 166 $   242 DKK / 39 $   

Natural gas (per Nm3)  0,01 DKK / 0,16 ¢  0,22 DKK / 3,5 ¢  

Due to these taxes the price of energy produced on biomass can compete with energy produced on fossil fuels and it is because of these taxes there are so many biomass fired district heating plants in Denmark. The approximate price of heat produced on different fuels is shown in figure 1.

Energy prices and taxes in Denmark

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A duty on 10 DDK (1,6 $) per kg SO2 has been imposed on SO2 emitted to the air or 20 DKK (3,2 $) per kg S in the fuel. The duty is imposed on sulphur containing fuels with a content of sulphur higher than 0,05%. However, straw and wood fired plants with thermal inputs less than 1 MW is exempted from the SO2-duty.

There is a major difference between the SO2-duty and other duties that only imposes on fossil fuels. The sulphur duty also imposes on biofuels, which has made it a hot issue for the Danish district heating plants. They compete against natural gas based combined heat and power production and because the natural gas only contains insignificant sulphur, no sulphur duty is payed for natural gas. This means that the competitiveness of the biofuels are weakened compared to the largest competitor, natural gas. Therefore, the Danish tax legislation is counteracting the energy plan, Energy 21.

Although the duty is supposed to reflect the emitted sulphur most heating plants will use the possibility given in the law to base the payable duty on the infeed amount of fuel. The reason for this is that the costs of measuring the emissions are large compared to the duty.

For straw the duty based on infeed fuel is 20 DKK (3,2 $) per ton while the duty is 11 DKK (1,8 $) per ton for dry wood. The duty for wood chips is reduced linearly with the water content, giving 6 DKK (1,0 $) per ton with a moisture content of 45%. For wood pellets the duty is 10 DKK (1,6 $) per ton and for pellets containing binder with sulphur in it the duty is 40 DKK (6,4 $) per ton.

The duty is gradually introduced by the use of a standard deduction, which is lowered each year. In the year 2000 the deduction is removed completely as it can be seen in figure 2.

Sulphur taxes for biofuels in Denmark

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SO2-duty on electricity

There is a special SO2-duty on electricity, which has been imposed because fuels for electricity production are exempted from SO2-duty until year 2000.

From January 1st 1996 to December 31st 1998 the duty is 0,9 øre (0,14 ¢) per kWh and from January 1st 1999 to December 31st 1999 the duty is 1,3 øre (0,21 ¢) per kWh. From the year 2000, where the power plants also pay SO2-duty, the SO2-duty on electricity will be dropped.

Repayment of energy duties

Because of the competitiveness of Danish companies, which have an energy requiring production, there is a possibility for their energy related duties to be repaid. This repayment is depending on what the energy has been used for. The energy consumption is divided into three different categories

  1. space heating and warm water, which is not a part of a production process
  2. processes with a moderate energy consumption, called a "light process"
  3. very energy requiring processes, called a "heavy process"

Exaples of heavy processes are cement or glass production, drying processes etc, while for instance pumping is a process with a moderate energy consumption, a light process.

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Environmental Legislation

According to Danish law on environmental protection, an approval by Danish authorities must be granted before a biomass fired plant with an input effect larger than 1 MW is constructed. The environmental demands are several.


The limits of emissions from biomass fired plants are given by regulation no. 6 1990 from the Danish Ministry of Environment on limiting air pollution from industries.

Input effect between 0,12 and 1 MW.

On these small plants, the maximum limit of dust emission is depending on the distance to the nearest dwelling:

The maximum allowed CO emission is 5000 ppm. The values are with a reference O2 concentration on 10%. With use of straw and wood as fuel, there is no limit values for SO2 and NOx.

Input effect between 1 and 50 MW

The maximum of dust emission, on plants of this size is 40 mg/Nm3 independent on distance to neighbors, and the limit value of CO concentration is 500 ppm. For plant larger than 1MW and approved after the first of January 1992, the limit value of NOx is 200 ppm.

There is a common quota for SO2 and NOx on power plants with an effect larger than 25 MW. The values are with a reference O2 concentration on 10%.

Input effect larger than 50MW

The limit values mentioned in this paragraph are with a reference O2 concentration on 6% except the value for CO, which is on 10%.

  dust (mg/Nm3)      SO2 (mg/Nm3)      NOx (mg/Nm3)         CO (ppm)      

       50              400-2000             200               600         

Also on these large power plants, there is a common quota for SO2 and NOx.

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The environmental legislation contains no regulation particularly related to ashes from wood and straw combustion, but ashes from these fuels can be distributed according to a regulation concerning waste products, which is not sludge, but normally approvals are based on "The Sludge Regulation" no. 730 of September 5th 1995.

There are two possible ways to meet the demands in the regulation. The first one is if the content of the different matters in the ashes is below a certain limit, and the other is if the content of different matters divided by the content of phosphorus is below another certain limit.

The limit values are shown below.

              mg/kg- dry ashes         mg/kg-total P        

     Cd              0,8                    200             

     Hg              0,8                    200             

     Pb              120                   10000            

     Ni              30                     2500            

     Cr              100                                    

     Zn             4000                                    

     Cu             1000                                    

Limit values for the most common metals in ashes. Regulation
no. 730 from September 5th 1995.

Normally plants fired with straw or wood have an approval, based on this sludge regulation, to distribute the ashes on cultivated land or in forests. Occasionally the content of heavy metals is above limit values, typically it is the content of cadmium which is too high. Many plants have a dispensation to distribute ashes with a content of cadmium higher than the limit value. To get a dispensation, the plants have to make an analysis of the ashes, typically containing values of the amount of cadmium, lead, mercury and nickel.

Control parameters

Heat and power plants have different control systems depending on size of the boiler.

Boiler installations can be divided up as shown

Normally, on the small boiler installations, there is no control system at all.

On the medium sized boilers, with a blower on both the combustion air and the stack air, there is a pressure gauge inside the boiler. This is done to make sure there is always a small vacuum, in order prevent gasses from the boiler from ending in the boiler room. Often there is an oxygen probe in the stack air. The signal from this probe is used to regulate the amount of secondary air. The amount of primary air is fixed in a way that it fits the amount of fuel supplied to the boiler.

The output effect from these plants are mostly controlled by an on/off regulation. With an on/off regulation, the temperature of the output water from the boiler determine whether the boiler installation is in "on mode" or in "off mode". When the temperature of the output water from the boiler is below a certain limit, fuel and combustion air will be carried to the boiler. When the temperature has reached another - and higher - certain limit, the supply of fuel to the boiler will stop, and after a while - when the fuel remaining in the boiler is burned out - the supply of combustion air stops.

District heating plants normally have a more advanced control system. On these plants there is a continuous fuel supply and it is the amount of fuel per time unit which determine the output effect of the boiler. The amount of fuel per time unit is determined by output temperature of the water from the boiler. Normally there is pre-programmed relation between the amount of primary air and the amount of fuel per time unit.

Furthermore, for instance on grate fired boiler, the residence time in the boiler can be controlled by variation of the velocity of the grate. On boiler plants with a step grate system, the residence time in the different parts of the boiler, can be regulated. That would be desirable for instance, if you change to more wet fuel, than you can increase the residence time in the first part of the boiler.

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This text is written by Torben Kvist Jensen and Søren Houmøller, Centre for Biomass Technology, dk-TEKNIK.



FORCE Technology. Last update: 03-05-00 10:40