In practice, this would require maintaining mothballed power plants or delaying the retirement of older units. According to the 2011 World Energy Outlook, reducing electricity end-use demand alone accounts for one-third of reduced greenhouse gas emissions over the next 10 to 15 years in the 450 ppm scenario. The potential for end-use efficiency improvements is enormous. National studies of economic energy efficiency improvements routinely estimate an economic energy savings potential of 20 to 25 percent over the next decade (McKinsey, 2009). Based on such projections, some governments have set ambitious targets of 10 to 15 percent for networked energy sales (gas and electricity) over the next decade (The State and Local Energy Efficiency Action Network, 2011).