Report: U.S. Grid Stable Without Coal by 2050

By Tommy Vitolo, Geoff Keith, Bruce Biewald, Tyler Comings, Ezra Hausman and Patrick Knight

Prepared for the Civil Society Institute

A “business as usual” strategy for the U.S. electric power industry, wherein the country continues to rely heavily on coal and other fossil fuels to meet its energy needs, is not tenable if we are to achieve substantial reductions in greenhouse gas emissions over the next several decades. In 2011, Synapse prepared a study for the Civil Society Institute, Toward a Sustainable Future forthe U.S. Power Sector: Beyond Business as Usual 2011 (BBAU 2011), that introduced a “Transition Scenario” in which the United States retires all of its coal plants and a quarter of its nuclear plants by 2050, moving instead toward a power system based on energy efficiency and renewable energy. Synapse’s study showed that this transition scenario, in addition to achieving significant reductions in emissions of CO2 and other pollutants, ultimately costs society less than a “business as usual” strategy—even without considering the cost of carbon. BBAU 2011 projected that, over 40 years, the Transition Scenario would result in savings of $83 billion (present value) compared to the business as usual strategy.

As part of this lower-cost and low-emissions strategy, the Transition Scenario included large
amounts of renewable energy resources with “variable output,” such as wind and solar. Without the inclusion of these resources, it will be difficult or impossible to reduce electric-sector greenhouse gas emissions to the levels necessary to materially mitigate our contribution to dangerous climate change.

While the need for variable-output resources is well defined, questions have been raised about the impact of large-scale wind and solar integration on electric system reliability.1 In light of this important concern, Synapse paid careful attention to the amount of wind and solar in each region when designing the Transition Scenario for BBAU 2011, taking steps to ensure that the projected regional resource mixes could respond to all load conditions. These steps included:

  •  improving the capability of the transmission system to handle large interregional power transfers;
  • ensuring that regions with high levels of variable generation also had high levels of flexible generation and capacity;
  • adding storage capacity in regions with high levels of wind generation;
  • strengthening the capability and flexibility of electric systems through transmission and distribution investments; and
  • developing robust demand-side management resources.

Our current study takes the analysis deeper, in order to explore the extent to which the Transition Scenario’s resource mixes for 2030 and 2050 are capable of meeting projected load for each of the ten studied regions—not just during peak demand conditions, but in every hour of every season of the year as consumers require. Using a simplified hourly dispatch model along with empirical load and resource output profiles, we assess the ability of the projected mix in each region to meet load under the varying conditions throughout a day, season, and year. An important limitation of the dispatch model is that it does not include the interregional transfers that were a fundamental part of the resource mix under BBAU 2011, as these have not been defined on an hourly basis. These transfers are an important part of the Transition Scenario for both economic and reliability reasons, and indeed we find that under certain extreme conditions, it is impossible to balance each region in isolation. Nonetheless, our analysis shows that the regional Transition Scenario resource mixes would be capable of meeting load for almost all hours of the year in each region, and that a combination of interregional transfers, local storage, and demand response would be more than adequate to provide a high level of reliability.

This analysis, along with BBAU, is solely based on today’s existing technology. We do not expect that the optimal sustainable electricity future for the United States will look exactly like our Transition Scenario, as we anticipate that changes in the technology and economics of carbon-free generation and energy storage will produce options that today would seem unachievable. What we demonstrate in this report is that strategies to address one of the most pressing challenges faced by our species and our planet are already not only achievable, but cost effective. Future developments will only improve this potential—it is up to policymakers to make this potential a reality.

To read the full report, go here:


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