France will be completely out of coal by January 1, 2027 for electricity production. This is what President Emmanuel Macron announced at the last ecological planning council on September 25, 2023. This is part of the national energy transition strategy to achieve carbon neutrality in 2050.

Of the four coal-fired power plants in France, two have already closed their doors. The last two are still active. A decree of 24 August 2023 extended their period of operation until the end of 2024 to deal with the energy crisis.

To reduce the environmental impact of thermal power plants, the State supports their conversion into biomass.

Why and how to convert a coal-fired power plant? Is using biomass as an energy source a good alternative to coal? The news is an opportunity to take stock of this controversial subject.

How does a thermal power plant work?

Coal-fired power plants and biomass belong to the family of thermal power plants. They produce 75% of the world's electricity. They are distinguished by the energy source used.

How does a thermal power plant produce electricity?

The thermal power plant uses the principle of thermal energy. It transforms heat into electrical current in a process in four steps:

• The first step is to produce heat, by burning fuel in a combustion chamber.

• The heat released is used to heat water and generate steam.

• Under pressure, steam drives a turbine connected to an alternator.

• The alternator produces alternating electrical current. After passing through the transformer, the current can be routed via the transport network.

At the end of the cycle, the steam is transformed back into water using a condenser. Cooled, it is reinjected into the production circuit. In the cogeneration, part of the steam is recovered to supply a local, residential or industrial heating network.

The fumes released during the process are filtered to eliminate dust. Released into the atmosphere, they contribute to global warming because of their high CO content.₂.

What is the difference between a coal-fired power plant and a biomass installation?

All flame-fired power plants follow the same process for converting heat into electricity and/or heating. Elles differ in the type of fuel burned. The majority uses fossil fuels, such as coal, fuel or gasses.

Coal remains the world's largest source of electricity. According to the report published in July 2023 by the International Energy Agency (IEA), it provided 36% of global electricity production in 2022. The power of the global fleet has even increased by... 19.5 GW. The reason for this craze? Affordable prices, the increase in industrial needs in the world and the revival of coal-fired power plants in Europe to meet gas supply problems.

Biomass appears to be a sustainable alternative to coal. A biomass thermal power plant produces electricity by burning vegetable raw materials, wood, organic household waste or even biogas from the fermentation of waste.

Why reconvert coal-fired power plants into biomass?

According to the American NGO Global Energy Monitor, the environmental transition in the world involves the Closure of coal factories and the development of renewable energies. This is the strategy followed by France. As part of ecological planning, the end of this fossil fuel is announced in 2027.

The environmental challenges of coal-fired power plants

Coal-fired power plants are in the sights of governments and environmental associations. It must be said that they combine the bad points in terms of the environment.

CO emissions₂ High

The environmental impact of coal is very unfavorable. According to ADEME, a coal-fired power plant emits 1,060 g CO equivalent₂ per kWh produced. In comparison, a nuclear installation emits 6 g CO₂E/kWh.

In its latest report, the IEA is sounding the alarm. Global CO emissions₂ from coal reached a new historic record in 2022 with nearly 15.5 Gt. They represent 42% of CO emissions₂ global energy-related, ahead of oil (11.2 Gt). For comparison, industry accounts for 9.2 Gt of CO₂.

Coal-fired power plants also emit methane and nitrogen oxides (NOx). These air pollutants play a major role in the greenhouse effect.

A fossil fuel

Coal is a fossil raw material. It results from the transformation of vegetable organic matter buried in the ground. Under the effect of high pressure and temperatures, they decomposed and transformed into a solid and combustible material with a high carbon content.

However, The reserves are not inexhaustible. In 2020, they were estimated at just over 1 trillion tons. At the current rate of consumption, the deposits could be exhausted within a hundred years.

Biomass contributes to environmental sustainability

Biomass is presented today as a sustainable solution to replace coal and reduce the environmental impact of thermal power plants. However, its limits are pointed out by some associations.

A renewable and local fuel

Biomass is a sustainable, renewable and local source of energy. It consists mainly of organic vegetable matter such as agricultural, agri-food or household waste, reclaimed wood or even biogas.

In France, she is of mostly solid origin. Composed of wood and pellets, it is mainly used for residential heating. Out of 132 TWh consumed in 2021, only 11 TWh were intended for electricity production.

Biomass has other advantages. Pilotable and storable, it offers a local solution for the recovery of organic waste. Elle also promotes energy autonomy territories, by offering consumers access to green and local energy.

A carbon neutral balance?

The combustion of organic materials generates carbon dioxide. However, it is considered that these releases of greenhouse gases are cancelled out by the quantity of CO₂ absorbed by plants during their growth. This short cycle ensures that biomass has Relatively neutral carbon footprint.

If the reduction in CO emissions₂ between coal and biomass is undeniable, environmental protection associations nevertheless remain cautious. They remind us that decarbonization is only possible under one condition: maintain a balance between planting plants, synonymous with CO absorption₂, and their combustion, synonymous with CO emissions₂.

They also fear that the multiplication of biomass installations threatens this balance and exerts increased pressure on forests, with a risk of deforestation.

How will French coal-fired power plants be converted to biomass?

While Emmanuel Macron has just announced the replacement of coal by biomass as part of the national ecological strategy, conversion projects have already been launched for commissioning no later than 2026.

The energy transformation project for the Cordemais power plant (Loire-Atlantique)

The Cordemais power plant decarbonization project has been under way since 2015 by the EDF group. Under the code name “Ecocombust 2”, its objective is threefold: to continue to cover a quarter of the electricity needs of Pays de la Loire, while decarbonizing production and maintaining local employment.

If the project is not met with resistance, “Black pellets” should replace coal by 2026. These are made from class B wood waste, such as furniture or building waste.

In 2019, during the test phases, Lionel Olivier, the director of the Cordemais thermal power plant, explained this choice: “With these pellets, we manage to have something that is very similar to coal in terms of behavior”.

The energy transformation project for the Saint-Avold power plant (Moselle)

Authorized to operate until the end of 2024, Saint-Avold power station also prepare for its transition. One carbon-free reindustrialization project of the factory is carried out by its operator GazelEnergie.

The first “black pellet” combustion tests are planned for winter 2024. The objective is to start the first works from April to October 2024, for a gradual reconversion of installations without stopping electricity production.

More generally, the operator intends to transform the site into an industrial eco-platform for the production of renewable and green energies, combining biomass, wind, photovoltaic and hydrogen.

With the conversion of its last two coal-fired thermal power plants into biomass, France would be “among the first in Europe to get out of coal” as stated by President Emmanuel Macron.

Environmental associations remain cautious. Would using biomass as an alternative to coal be a false good idea? While it allows the reduction of carbon emissions, biomass has limits — like all sustainable solutions.

Between the emissions of fine particles, the corrosion of equipment, the pollution of transport for the supply of pellets and the risk of deforestation, the carbon and financial balance of biomass could quickly become unfavorable.

To succeed in energy transition, France must remain vigilant about the origin of organic waste, monitor forest management and maintain the balance between production and consumption of organic matter.

To go further, do not hesitate to consult our article on natural carbon sinks.