Transition from coal: biomass as a sustainable alternative

Although coal consumption in the European Union is steadily declining, hundreds of coal-fired power and heat generation units remain in operation. As EU regulations increasingly restrict high-emission energy sources, a regulated transition away from coal is underway. Conversion to biomass lowers CO₂ emissions, provides more stable pricing than imported coal, and existing boilers can often be converted with minimal investment. Our technology enables the conversion of all water-tube coal boilers to biomass.

Fuel conversion without new construction

Adapting boilers for biomass combustion offers both environmental benefits and strong economic value - especially because no new boiler house construction is required. The conversion can be carried out within the existing infrastructure, which cuts investment costs, shortens project timelines. It also preserves the current site designation, avoiding additional permits or land-use changes, and allows continued use of existing utility connections.

TECHNOLOGY

The Energy ON’s integrated grate

technology

enables precise adaptation of its geometry during

the design phase to align with both existing and

newly developed boiler configurations, as well as the

specific type of biofuel being used.

The uniquely designed air holes in the

grates ensure even air distribution

allowing for precise control of the combustion

process location and significantly reducing the

carryover of solid particles from the

combustion surface.

Additionally, the system features three

independently controlled moving grate zones

providing a dynamic solution for adjusting fuel layer

thickness in different areas of the grate and

optimizing combustion based on fluctuating biofuel

quality parameters.

The grate’s specialized relief structure

enhances fuel layer mixing

which is especially beneficial when burning less

homogeneous or high-moisture biofuels.

CASE STUDY

Adaptation of the existing coal-fired water heating boiler WR-25 for biomass combustion.

ENVIRONMENTAL PERSPECTIVE

Old coal boiler (29.1 MW, η = 81%)

Emissions were high – solid particles directly after the boiler reached 1000–5000 mg/m³, reduced to 88 mg/m³ after cyclones. NOx (371 mg/m³) and SO₂ (579 mg/m³) values were significant, reflecting coal’s sulfur and nitrogen content. CO levels (81 mg/m³) indicated complete combustion. Overall, the system had a heavy environmental footprint, with major contributions to air pollution (dust, acidifying gases, and greenhouse emissions).

Retrofitted biofuel boiler (23.5 MW, η = 91%)

Emissions are reduced – solid particles after the ESP reach only 1.9 mg/m³, which is well within modern environmental standards. NOx dropped to 162 mg/m³, SO₂to a negligible 4.5 mg/m³, and CO to 32 mg/m³, showing cleaner combustion and very low sulfur content of biofuels. This represents a clear environmental improvement with reduced local air pollution and better alignment with EU emission directives.

ENGINEERING PERSPECTIVE

Old coal boiler (29.1 MW, η = 81%)

The system was relatively powerful, but efficiency was modest at 81%, with significant losses. High SO₂ emissions contribute to air acidification, leading to acid rain that damages soils, forests, crops, and aquatic ecosystems. SO₂ also contributes to respiratory problems in humans and forms fine secondary particles that worsen air quality.

Retrofitted biofuel boiler (23.5 MW, η = 91%)

Nominal power is slightly lower, the efficiency has improved 91%, meaning more useful energy is produced per unit of fuel. The system uses an electrostatic precipitator (ESP), which provides excellent dust removal performance (down to 1.9 mg/m³). Improvements in combustion technology have reduced NOx and CO emissions. This reduction lowers the risk of chemical smog, improves air quality, and reduces the environmental load on ecosystems. The switch to low-sulfur biofuel practically eliminated SO₂ emissions.