Abby L. Harvey
GHG Monitor
12/4/2015
It is technically feasible, in four unique scenarios, for the United States to reduce its greenhouse gas emissions 80 percent below 1990 levels by 2050, according to the latest Deep Decarbonization Project U.S. Pathways report. “Four distinct scenarios employing substantially different decarbonization strategies —High Renewable, High Nuclear, High CCS, and Mixed Cases … — all met the target, demonstrating robustness by showing that redundant technology pathways to deep decarbonization exist,” the report says.
The four cases vary greatly and are named to express where the biggest changes in the energy sector occur. The High Renewables case sees renewables, primarily wind and solar, dominating energy generation. Under the High Nuclear case, atomic energy accounts for more than one-third of energy generation by 2050. Fossil energy power generation equipped with carbon capture and storage provides more than half of the nation’s energy in the High CCS case, resulting in the closest match to the current energy mix. The Mixed Case balances the other three, displaying the most technologically diverse option.
The report also finds that reaching such a level of decarbonization is both technically and economically feasible. “Achieving this level of emissions reductions is expected to have an incremental cost to the energy system on the order of 1% of GDP, with a wide uncertainty range,” the report says.
Furthermore, electricity rates under nearly all cases stay essentially on par with the reference business-as-usual case. “Despite significant differences in rate components, average rates in all cases are similar to Reference Case levels … with the High CCS Case representing the only significant rate increase (27 [percent] over Reference Case rates) and the High Nuclear Case showing only a slight rate increase (5 [percent]) under base technology cost assumptions.”
However, the cost estimates presented in the study are uncertain, the authors warned: “They depend on assumptions about consumption levels, technology costs, and fossil fuel prices nearly 40 years into the future.”
The study also asserts that under these scenarios, the U.S. can maintain its long-term commitment to working toward the international goal of limiting global warming to 2 degrees Celsius. “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. In addition, the 2°C goal plays a critical role as a guide for near-term mitigation efforts, providing a benchmark for the necessary scale and speed of infrastructure change, technical innovation, and coordination across sectors that must be achieved in order to stay on an efficient path to climate stabilization,” the report says.
