Greening growth or greenwashing capital? How financialisation and education shape the ecological returns of renewable energy investment in Italy

Italy's ecological sustainability depends critically on the financial and human capital structures that mediate the environmental returns of renewable energy investment (REI). This study examines how REI, financialisation (FIN), education (EDU), and economic growth (GDP) jointly influence Italy's load capacity factor (LCF) over 2001Q1–2023Q4, by employing Kernel-Regularised Least Squares (KRLS) and Quantile-on-Quantile Regression (QQR) techniques to capture nonlinear and distribution-sensitive dynamics. The Brock–Dechert–Scheinkman (BDS) nonlinearity test confirms significant nonlinear dependence across all series. Aggregate results reveal that REI significantly improves LCF, while FIN exerts a predominantly negative average effect that reverses sign at upper quantiles, suggesting ecological realignment as financial markets mature. EDU consistently enhances LCF, with amplifying effects at higher quantiles. The interactions FIN*REI and EDU*REI are both positive and significant, confirming that financial depth and human capital function as ecological complements that amplify the environmental returns of REI. Disaggregate analysis reveals technology-specific heterogeneity: hydropower, solar, and wind improve LCF, whereas bioenergy and geothermal impose negative effects attributable to land-use competition and resource-extraction pressures. GDP exerts a persistently negative effect, with no evidence of a turning point in the Environmental Kuznets Curve. The findings carry direct policy implications for aligning Italy's financial system, human capital strategy, and renewable energy frameworks with its SDG commitments.