Abby L. Harvey
GHG Monitor
12/5/2014
The United States can reduce its total greenhouse gas emissions by 80 percent below 1990 levels by 2050, according to a report released last week by the Deep Decarbonizatrion Pathways Project (DDPP). The DDPP is led by the Sustainable Development Solutions Network (SDSN) and the Institute for Sustainable Development and International Relations (IDDRI). The report identified three key factors to reaching the 80 percent goal: highly efficient use of energy in buildings, industry and transportation; decarbonization of electricity and other fuels; and fuel switching of end uses to electricity and other low-carbon supplies. “All of these changes are needed, across all sectors of the economy, to meet the target of an 80 [percent] GHG reduction below 1990 levels by 2050,” the report says.
Within the U.S. energy system, the report concludes, unmitigated fossil fuel use would decline greatly in all the scenarios presented (High Renewables, High Nuclear, High CCS and Mixed Case), demonstrating a need for the deployment of CCS if fossil fuels are to remain a significant part of the U.S. energy mix as they do in the High CCS case. “Decarbonized energy systems of 2050 would look fundamentally different from those of today. Historically, U.S. primary energy supply has been dominated by fossil fuels, which have accounted for well over 80 [percent] of primary energy use throughout the past 60 years. By contrast, meeting a 750 Mt CO2 target would require reducing uncontrolled combustion of fossil fuels to at least 80 [percent] below current levels, a 10-fold decrease in carbon emissions per capita and a 15-fold decrease in carbon emissions per dollar of GDP,” the report says.
Generation Will Need to Increase Going Forward
Several changes need to be made to meet the 80 percent goal, the report says, acknowledging that transforming the U.S. energy system will be a gradual process. “With commercial or near-commercial technologies and limits on biomass availability and carbon capture and storage (CCS) deployment, it is difficult to decarbonize both gas and liquid fuel supplies. For this reason, meeting the 2050 target requires almost fully decarbonizing electricity supply and switching a large share of end uses from direct combustion of fossil fuels to electricity (e.g., electric vehicles), or fuels produced from electricity (e.g., hydrogen from electrolysis). In our four decarbonization cases, the use of electricity and fuels produced from electricity increases from around 20 [percent] at present to more than 50 [percent] by 2050,” the report says.
However, with an increasing demand for electricity, generation will need to double while its carbon intensity is decreased 3-10 percent, according to the report. “Concretely, this would require the deployment of roughly 2,500 gigawatts (GW) of wind and solar generation (30 times present capacity) in a high renewables scenario, 700 GW of fossil generation with CCS (nearly the present capacity of non- CCS fossil generation) in a high CCS scenario, or more than 400 GW of nuclear (4 times present capacity) in a high nuclear scenario,” according to the report.
Further the report finds that all aspects of reaching the goal of an 80 percent decrease in GHGs by 2050 are feasible. “This study did not find any major technical or economic barriers to maintaining the U.S. long-term commitment to reducing GHG emissions consistent with limiting global warming to less than 2°C. In terms of technical feasibility and cost, this study finds no evidence to suggest that relaxing the 80 [percent] by 2050 emissions target or abandoning the 2°C limit is justified,” the report says.
