Assessing the potential for biomass savings through targeted retrofitting of district heating systems in Austria

Biomass district heating plants are central to renewable heat supply in rural Austria, but growing competition for limited biomass resources requires more efficient use of existing infrastructure. This study presents a techno-economic assessment of retrofit measures for the Austrian biomass district heating sector. Plants are grouped into representative clusters and evaluated for combustion optimization, passive and active flue gas condensation, and waste-heat heat pump integration under varying energy price scenarios. Results are projected into sector-wide rollout pathways to 2050. Active flue gas condensation emerges as the most broadly viable measure, adopted by 36%–84% of plants across scenarios. Heat pumps deliver the largest per-plant biomass savings but depend on waste heat availability and electricity prices. Plants near hydropower facilities achieve levelized costs approximately 13 EUR/MWh lower than grid-connected configurations. Waste-heat heat pumps also provide operational flexibility, with 14.4% of their annual electricity consumption shiftable in response to hourly price signals. The findings provide a basis for prioritizing retrofit investments and designing targeted policy support across plant types and market conditions.