The committee concluded that there are two significant barriers to accelerating greater penetration of increasingly clean electricity technologies. First, as noted above, the market prices for electricity do not include “hidden” costs from pollution, stemming mainly from negative impacts on human health, agriculture, and the environment. Levels of criteria pollutants declined over the past three decades, but still cause harms. Harms from GHGs are difficult to estimate, but if accounted for in the market, could be considered by consumers.

In most locations within the United States, prices for increasingly clean power technologies are higher than those for less clean, incumbent technologies. While costs have declined over the past several years for some increasingly clean technologies—notably solar photovoltaics—natural gas supplies have opened up, causing dramatic decreases in natural gas prices. There are notable locations where unsubsidized wind- and solar-generated electricity is competitive with or cheaper than electricity from other sources. Yet for most of the country, most of the time, the prices of dirtier incumbent electric power generation technologies are lower than those of increasingly clean technologies, in part because their price does not include their full costs. Thus they are built and utilized more often and in turn produce more pollution than would be the case if their prices were correct.

Inaccurate price is an example of a “market failure” where government action is often justified. In this case, the solution to correct the market failure is intellectually simple but politically difficult: governments can require that market actors include the price of pollution in their decision making. This has been done in some form with SO x and NO x since the early 1990s and in limited ways for GHGs since the late 2000s.

The second barrier is that the scale of the climate change challenge is so large that it necessitates a significant switch to increasingly clean power sources. In most of the United States, however, even with a price on pollution, most increasingly clean technologies would lack cost and performance profiles that would result in the levels of adoption required. In most cases, their levelized costs are higher than those of dirtier technologies, and there are significant challenges and costs entailed in integrating them into the grid at high levels. This means that reducing the harmful effects of emissions due to electricity generation will require a broader range of low-cost, low- and zero-emission energy options than is currently available, as well as significant changes to the technologies and functionality of the electricity grid and the roles of utilities, regulators, and third parties.

Lastly, the committee notes that even if the technological and institutional barriers to greater adoption of increasingly clean power technologies were overcome but their prices were not competitive, an adequate scale of deployment would require tremendous public outlays, and in many parts of the world would be unlikely to occur. While learning by doing can lower some