projects were enormous technological and organizational triumphs, to be sure, but they were generally disconnected from the daily lives of the nation’s citizens. Nevertheless, particular technological elements—such as CCS, advanced batteries for transportation, advanced geothermal energy for electricity production, and low-cost efficient lighting and solar panels—might very well benefit from focused development and demonstration programs even as the many nontechnological challenges are being addressed.

The focus of this study, consistent with its charge (Box 1.1), is on energy-supply and end-use technologies—in particular their deployment-readiness, performance, costs, barriers, and impacts. The AEF Committee also assessed the prospects of some other technologies that will be critical both in meeting the anticipated growth of energy demand and in enabling the deeper market penetration of the new energy-supply and end-use technologies themselves. These critical technologies range from CCS, which would support not only the continued use of fossil fuels for electricity generation but also any future production of liquid fuels, to advanced battery, fuel-cell, and hydrogen technologies.

The committee considered technology development and deployment over three time periods—2008–2020, 2020–2035, and 2035–2050—but focused mainly on the first two periods, not only because the more distant future is harder to analyze but also because it depends critically on what occurs (or does not occur) earlier. Notably, the committee found that what can be realized in the two later periods will be contingent on the accomplishments in the critical first period, which is immediately ahead of us. Indeed, a major message of this report is that the nation can achieve the necessary and timely transformation of its energy system only if it embarks on an accelerated and sustained level of technology development, demonstration, and deployment along several parallel paths between now and 2020. The cases for such urgent actions are strikingly similar in virtually all of the energy domains addressed in this report, whether they pertain to specific energy-supply technologies, end-use technologies, or electricity transmission and distribution.

In addressing its study charge, the committee avoided reinventing the wheel. Where appropriate, it took advantage of the existing energy literature, which is both extensive and information-rich, to inform its judgments. In some selected