using technology that is deployable now or is likely to be deployable soon, include the following:

  • Improved efficiency in the use of electricity and fuels, especially in the buildings sector, but also in industry and transport vehicles.

  • Substitution of low-GHG-emitting electricity production processes, which may include renewable energy sources, fuel switching to natural gas, nuclear power, and electric power plants equipped to capture and sequester CO2.

  • Displacement of petroleum fuels for transportation with fuels with low or zero (net) GHG emissions.

Meeting the goal of limiting domestic GHG emissions to 170 Gt CO2-eq by 2050, by relying only on these near-term opportunities, may be technically possible but will be very difficult. Meeting the 200 Gt CO2-eq goal is more feasible but nevertheless very demanding. In either case, realizing the full potential of known and developing technologies will require reducing many existing barriers to deployment; therefore, it is likely these technologies will fall short of their technical potential.

This underscores the crucial need to strongly support R&D aimed at bringing new technological options into the mix (discussed further in Chapters 4 and 5). Meeting the 2050 budget goal requires that these new technologies be available by the 2020-2030 time period. To create the necessary innovations in time for deployment means moving research along very rapidly.

Some important opportunities exist to control non-CO2 GHGs including CH4, N2O, long-lived fluorinated GHGs, and short-lived pollutants such as ozone precursors and black carbon aerosols. Opportunities also exist to enhance biological uptake and sequestration of CO2 through afforestation and soil management practices. These opportunities are worth pursuing, especially as part of a near-term strategy, but they are not large enough to allow the United States to avoid falling short in reducing emissions from fossil fuel energy sources.

Our nation’s existing energy system, if left unchanged, will rapidly consume the emissions budgets suggested in Chapter 2 (especially the more stringent 170 Gt CO2-eq budget). Delay in reforming the energy system would thus make a challenging goal essentially unattainable.

Because of this compelling case for urgency, we conclude that action is needed: to accelerate the deployment of technologies that offer significant near-term GHG emissions-reduction opportunities; to accelerate the retirement or retrofit of existing high-emitting infrastructure; and to aggressively promote research into the development and deployment of new, low GHG-emitting technologies.

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