Research can help to address fundamental scientific challenges and foster technologies that are considered too risky, uncertain or long-gestating for the private sector. The IEA tracks government research, development and demonstration (RD&D) expenditure in member countries for energy efficiency and energy sources and compares those levels with total RD&D spending (See Figure 2.4). As well, public spending on low-carbon energy RD&D for about nine technologies, energy efficiency in industry and buildings, carbon capture and storage, and smart grids are available through IEA statistics and could be useful in the development of green growth indicators for the energy sector. Information on the financing of clean energy technologies involving risk or equity capital can help to assess innovation that is moving closer to commercial application in the marketplace.