Global investment in energy end-use technologies was more than double the supply-side investments, and reached an estimated $1.7 trillion in 2005, of which almost $1.2 trillion was for road vehicles (Griibler and others, forthcoming). Other private sector investments in energy technology include investment by angel investors, companies’ internal investments, debt instruments, project finance, mergers and acquisitions, and investments in publicly listed energy technology firms. Energy-related venture capital investments boomed in EU and North America in recent years, reaching $15.5 billion, or 10 per cent of all private investments in energy technology diffusion in 2008 (International Energy Agency, 2009).