The cost of capital is an important input for power sector and energy system models, used widely across industry, academia and government to explore future decarbonisation scenarios. The levelised cost of electricity is sensitive to the assumed cost of capital (particular for renewables due to their high capital intensity), but empirical data on the cost of capital is typically outdated, geographically limited and difficult to access. It is also limited to markets which have seen recent deployment of corresponding electricity generation technologies, driving a data availability gap for emerging and developing economies. Here, we present a database which includes historical, current and future estimates of the cost of capital for 10 electricity generation technologies from 2015-2024: 1) solar photovoltaic (PV), 2) onshore wind, 3) offshore wind, 4) hydroelectric power, 5) biomass, 6) natural gas combined cycle turbines (CCGTs), 7) CCGTs equipped with carbon capture and storage, 8) geothermal, 9) tidal and 10) wave power. Note that nuclear is excluded due to the unique risks faced by project developers. In addition, we provide short term forecasts of the cost of capital out to 2030, which are an important input for accurate technoeconomic assessments. The data are global in scope but with national and technology specificity, covers the years 2015 through to 2030, and span 27,640 datapoints across 176 countries. The database addresses the limited empirical data on cost of capital available and enables enables modellers to select and justify model input data. The estimates presented here have been verified through comparison to historical data, with the estimation approach informed by stakeholder engagement and results from an expert elciitiation survey. Version two has been adjusted to include more in-depth treatment of technology risk premiums. An interactive webtool is also provided to visualise and explore the results, including underlying contributions to the cost of capital: https://wacc-forecaster.streamlit.app/ UPDATE FEB 2025: Increased coverage of technologies, with technology premiums now derived from "Hurdle rate estimates for electricity sector technologies" performed by CEPA for DESNZ in 2025 that were not available at the time of submission The approach to calculating the cost of debt has been slightly modified, with more detailed treatment of the potential overlaps between the infrastructure lenders margin and the technology risk premium i.e. to avoid potential double counting, the lenders margin is subtracted from the technology risk premium Updated country risk premium for 2025 now that data is available from Damodaran Short term projections have been extended to 2036 (10 years) Updated forecasts of 10-year Treasuries from the CBO's Budget and Economic Outlook 2026 - 2036, which have changed notably following the macroeconomic disruption in 2025