Finnish energy system can be made 100% fossil free

In Finland, 40% of the total energy consumption including electricity, heating, transport, and industry is still based on fossil fuels. Fossil fuels can be replaced mainly by electricity-generating technologies using wind, solar, biofuels and nuclear as primary energy sources. This means that a higher degree of electrification is needed in both the heating and transport sectors. 

Figure 1: Primary energy sources in Finland 2017. All fossil fuels should be replaced by clean energy sources before 2040.

Fossil fuel-free energy scenario for Finland

The following scenario for a 100% fossil fuel-free Finnish energy system includes all sectors of energy use. It has been made simulating clean energy production technologies and storages using EnergyPLAN-simulation program, that aims to balance power and heat production and consumption hour by hour. The simulation is made in a deterministic way, trying to minimize the total fuel input in the system with optimization.

Energy sources and installed capacity in the 100% fossil fuel-free energy scenario

The simulation shows that the Finnish energy system can be made 100% fossil fuel-free. 95% of the energy sources are resolved in the simulation as they can be produced at a moderate cost, with proven technologies as well as readily available renewable energy sources and nuclear power. The remaining 5% is liquid or gas fuels needed in long-distance transportation, aviation and to a smaller extent also in the most flexible part of peak power production. These fuels can be produced with wind, solar, biomass or nuclear.

Table 1. The primary energy sources in Finland 2017 and in 100% fossil fuel-free scenario for comparison. Hydropower 15 TWh, recycled fuels 9 TWh and reaction heat from industries 2 TWh are assumed to remain on the level of 2017, and therefore not included in the table.

Energy sources Consumption in Finland, 2017 Consumption in 100% fossil-free scenario
Wind power 5 TWh 60 TWh
Ambient (ground, sea, air, geothermal) and excess heat 6 TWh 38 TWh
Biomass 100 TWh 110 TWh
Nuclear fuels, uranium 65 TWh 106 TWh (36 TWh power)
Solar power 0 TWh 3 TWh
Clean fuels 16 TWh
Net imports or exports of electricity 20 TWh imports 5 TWh exports
Fossil fuels Natural gas 18 TWh, oil 87 TWh, coal 33 TWh and peat 15 TWh

Energy sources and assumptions in 100% fossil fuel-free scenario

Wind power is assumed to increase and it will be the largest single source of electricity. This is considered realistic as wind power is currently the cheapest energy source in Finland with a production cost of 30-35 eur/MWh and very large growth potential. The capacity factors of the new wind turbines have recently increased to over 40%.

Ambient and excess heat includes heat taken from the sea, lake, river, air, ground, geothermal sources and various urban excess heat sources like wastewater and exhaust air, and used by heat pumps. This can also be very deep geothermal heat.

Biomass is already now a major source of renewable energy in the Finnish energy system. The scenario assumes only minor growth of biofuels originating i.e. from the enhanced collection of logging residues, and agricultural residues. The Finnish economical biogas potential is approximately 10 TWh and main sources are various agricultural residues. Since the availability of sustainable biomass is limited, biofuels must be used sparingly. Therefore, we suggest using biomass in combined heat and power plants (CHP) for maximal efficiency.

Nuclear fuels include the energy content of the nuclear fuel used: the level of uranium use in 2017 and that of the Olkiluoto 3 EPR reactor, which is under construction. 106 TWh uranium use in the scenario translates to 36 TWh power production.

Hydropower production is assumed to remain at the current level.

Solar energy and, in particular solar photovoltaics (PV) will significantly increase in buildings especially to meet their cooling demand. Solar electricity production also complements wind power production during summers. Solar thermal heating is not part of this scenario because, according to hourly simulation, seasonal heat storages were not yet an optimal solution. Solar heating potential can, however, grow in the future depending on the development of the electric and heat storage solutions.  

Alternative clean fuels not specified in this scenario include liquid and gas fuels that are needed for example in long-distance road transportation, aviation, peaks of electricity and heat production, and some industrial processes. These fuels can be biofuels requiring additional biomass use on top of the 110 TWh assumption in this scenario, or liquids or gases converted from renewable or nuclear electricity. Renewable electric energy can be transformed into storable methane via electrolysis and subsequent methanation. For example, biogas can be used as carbon dioxide source in power to gas (PtG) process chain and higher methane content can be achieved. Some of these technologies are still under development. In this scenario, the energy sources of the fuels are left open for discussion.

Imports and exports of electricity. A small amount of imports, about a third of the amount of 2017, and exports is allowed as an assumption in the simulation. The electricity is assumed to be transmitted without limits inside Finland. In the scenario Finland will turn to be a net exporter of electricity, exporting approximately 5 TWh of electricity to Nord Pool or Russian power markets annually. The amount of imports is very low compared to the situation in 2017. 

Installed energy capacity and assumptions in 100% fossil fuel-free scenario

Table below shows the changes in the installed power and heating capacities in Finland 2017 and in the 100% fossil-free scenario. 

Table 2. Differences in installed energy production capacity in Finland between year 2017 and 100% fossil-free scenario.Industrial CHP 2900 MW and hydropower 2700 MW are assumed to remain the present level, and therefore they are not included in the table.

Energy production capacity Installed capacity in Finland, 2017 Installed capacity in 100% fossil-free scenario
Electricity Heat Electricity Heat
Wind power 2 000 MW 19 000 MW
Solar power 70 MW 4 000 MW
CHP, district heating 3 200 MW 4 600 MW 1 500 MW 2 300 MW
Nuclear power 2 700 MW 4 300 MW
Heat pumps in district heating networks 250 MW 6 000 MW
Heat only boilers 12 000 MW 4 000 MW –
12 000 MW
Condensing power 2 000 MW 1 600 MW
Electric boilers in district heating networks 1 000 MW


Wind and solar power capacity grows significantly. The amount of district heating CHP capacity will reduce to about half of the 2017 level, due to the decommissioning of plants which can only or mainly use coal or natural gas. The remaining district heating CHP plants with fluidized bed boilers can quite easily be converted to 100% biomass.

Heat pump capacity will be built to the district heating networks and industry, and it will also replace oil combustion and 5 TWh (out of 17 TWh) of small-scale wood use, in the residential sector.

Heat only boilers are covering heat demand peaks in district heating networks with CHP. Electric boilers are used to convert peaks of excess electricity to heat. Condensing power in the fossil fuel-free scenario consists of condensing tails and auxiliary coolers of bio-CHP plants, i.e. not separate thermal power plants. Condensing power production is used in the scenario only as minor backup, as separate thermal power inefficiently wastes about 50-70% of the fuel. Existing gas turbines in Fingrid’s power reserves are assumed to remain in the scenario.

Photo: Onni Jaskari

We also assume that the system contains 10 terawatt hours (TWh) of flexible demand: 5 TWh in electric vehicles and another 5 TWh in heating, especially in detached houses. In addition, the heat storages will grow from the current 0,02 TWh to 0,1 TWh in the scenario.

More information:

Samuli Rinne, Karoliina Auvinen, Francesco Reda, Salvatore Ruggiero and Armi Temmes. 2018. Discussion paper: Clean district heating – how can it work? (pdf). Publication of the Smart Energy Transition project funded by the Academy of Finland’s Strategic Research Council.

Web articles: Clean electricity production must increase massively to replace fossil fuel combustion and Clean district heating and cooling system – how can it work?

Stakeholder Relations Director, Researcher Karoliina Auvinen, Aalto University,, +358 50 4624727