Perfecting these technologies, and finding new ones, will require a clear price on carbon, targeted government-funded R&D, and policies to reduce the financial risks. Carbon pricing and support for innovation may not be enough to ensure all energy-efficiency options are adopted or accessible. Additional targeted regulatory instruments (such as fuel, vehicle and building-efficiency standards) may also be required. If designed to overcome market barriers and avoid costly overlap with market-based instruments, they can accelerate the uptake of clean technologies, encourage innovation and reduce emissions cost-effectively. The net contribution of the instrument “mix” to social welfare, environmental effectiveness and economic efficiency should be regularly reviewed.