In view of the growing challenges related to energy transition and the need to implement circular economy principles, the use of waste from the wine industry as bioenergy raw materials is becoming increasingly important. The aim of the study was to assess the energy potential of biomass in the form of grape stems and pomace from four varieties (PIWI)—Hibernal, Muscaris, Regent and Seyval Blanc—grown in south-eastern Poland. The analyses included the determination of technical and elementary parameters, pollutant emission indicators and exhaust gas composition parameters. The pomace was characterised by a higher calorific value, higher carbon (C) and hydrogen (H) content and lower dust emissions compared to the stems, but with higher carbon dioxide (CO2) emissions. Stems had a higher ash content, which may limit their energy use. The Hibernal variety achieved the highest calorific values at low moisture and low sulphur content, while Muscaris was characterised by increased nitrogen and sulphur content and higher sulphur dioxide emissions (SO2) and dust emissions. The Regent variety showed relatively high nitrogen oxides (NOX) emissions. Cluster analysis confirmed the diversity of varieties in terms of energy potential and waste biomass quantity. The results indicate that waste from PIWI grapevine cultivation can be a valuable local raw material for renewable energy production, contributing to waste reduction and greenhouse gas emissions in the agricultural sector, but its suitability depends on the variety and type of biomass.