NREL: North American Renewable Integration Study Highlights Opportunities for a Coordinated, Continental Low-Carbon Grid

The North American electric power system is undergoing significant change, with renewable resources now contributing more generation than ever before—a transformation that is poised to continue given decreasing technology costs and ambitious decarbonization goals at the federal, state, local, corporate, and consumer levels.

With a series of reports released today by the National Renewable Energy Laboratory (NREL), the North American Renewable Integration Study (NARIS) aims to inform grid planners, utilities, industry, policymakers, and other stakeholders about challenges and opportunities for continental system integration of large amounts of wind, solar, and hydropower to support a low-carbon future grid. The NARIS project began in 2016.

“We used a suite of models to study a range of future scenarios and gain insights—including potential impacts on costs, emissions, resource adequacy, and the specific technologies that help enable the transition,” said Greg Brinkman, NREL energy analysis engineer and principal investigator for NARIS. “Our analysis focused in particular on the potential role of cooperation across North America and between regions within each country, and how transmission can support sharing of supply and demand diversity across the continent.”

NREL has released a report on the U.S. perspective in coordination with the U.S. Department of Energy (DOE), and a companion report describing a Canadian perspective in coordination with Natural Resources Canada.

Results show that a future low-carbon North American grid can be achieved through multiple pathways that can balance supply and demand using a variety of flexible resources. The study also shows that increasing electricity trade and expanding transmission could have significant benefits, highlighting opportunities for a coordinated, low-carbon continental grid.

First-of-a-Kind Power System Modeling for the Entire Continent
With input from the NARIS Technical Review Committee, NREL developed and evaluated a set of four scenarios to understand the impacts of future renewable technology costs, emission constraints, and growth in electricity demand on key study outcomes. The scenarios were informed by the goals set in 2016 for the Paris Agreement in each country, with up to 80% carbon reductions continent-wide by mid-century.

Leveraging NREL’s high-performance computing capabilities, NREL evaluated the scenarios using a variety of models, including NREL’s Regional Energy Deployment System (ReEDS), Distributed Generation Market Demand (dGen™) model, and Probabilistic Resource Adequacy Suite (PRAS), as well as Energy Exemplar’s PLEXOS tool. All modeling was sourced by consistent data sets through the NREL Renewable Energy Potential (reV) model, National Solar Radiation Database (NSRDB), and WIND Toolkit.

“NARIS builds on decades of previous work studying power systems with high levels of renewable generation, including the Western Wind and Solar Integration Study, Eastern Renewable Generation Integration Study, Interconnections Seam Study, and Pan Canadian Wind Integration Study,” Brinkman said. “Here, we analyzed the entire continent in detail while studying higher renewable generation than these previous studies.”

Four key findings emerged from the analysis.

Finding 1: Multiple Pathways Can Lead to 80% Power-Sector Carbon Reduction Continent-Wide by 2050
Steeper cost reduction of wind and solar technologies can lead to a faster and less costly transition, and carbon targets can still be achieved with conservative wind and solar cost assumptions. When it comes to total system costs of achieving 80% power-sector emissions reductions, wind and solar cost trajectories have a more significant impact than carbon policy assumptions.

The North American electric power system is undergoing significant change, with renewable resources now contributing more generation than ever before—a transformation that is poised to continue given decreasing technology costs and ambitious decarbonization goals at the federal, state, local, corporate, and consumer levels.

With a series of reports released today by the National Renewable Energy Laboratory (NREL), the North American Renewable Integration Study (NARIS) aims to inform grid planners, utilities, industry, policymakers, and other stakeholders about challenges and opportunities for continental system integration of large amounts of wind, solar, and hydropower to support a low-carbon future grid. The NARIS project began in 2016.

“We used a suite of models to study a range of future scenarios and gain insights—including potential impacts on costs, emissions, resource adequacy, and the specific technologies that help enable the transition,” said Greg Brinkman, NREL energy analysis engineer and principal investigator for NARIS. “Our analysis focused in particular on the potential role of cooperation across North America and between regions within each country, and how transmission can support sharing of supply and demand diversity across the continent.”

NREL has released a report on the U.S. perspective in coordination with the U.S. Department of Energy (DOE), and a companion report describing a Canadian perspective in coordination with Natural Resources Canada.

Results show that a future low-carbon North American grid can be achieved through multiple pathways that can balance supply and demand using a variety of flexible resources. The study also shows that increasing electricity trade and expanding transmission could have significant benefits, highlighting opportunities for a coordinated, low-carbon continental grid.

First-of-a-Kind Power System Modeling for the Entire Continent
With input from the NARIS Technical Review Committee, NREL developed and evaluated a set of four scenarios to understand the impacts of future renewable technology costs, emission constraints, and growth in electricity demand on key study outcomes. The scenarios were informed by the goals set in 2016 for the Paris Agreement in each country, with up to 80% carbon reductions continent-wide by mid-century.

Leveraging NREL’s high-performance computing capabilities, NREL evaluated the scenarios using a variety of models, including NREL’s Regional Energy Deployment System (ReEDS), Distributed Generation Market Demand (dGen™) model, and Probabilistic Resource Adequacy Suite (PRAS), as well as Energy Exemplar’s PLEXOS tool. All modeling was sourced by consistent data sets through the NREL Renewable Energy Potential (reV) model, National Solar Radiation Database (NSRDB), and WIND Toolkit.

“NARIS builds on decades of previous work studying power systems with high levels of renewable generation, including the Western Wind and Solar Integration Study, Eastern Renewable Generation Integration Study, Interconnections Seam Study, and Pan Canadian Wind Integration Study,” Brinkman said. “Here, we analyzed the entire continent in detail while studying higher renewable generation than these previous studies.”

Four key findings emerged from the analysis.

Finding 1: Multiple Pathways Can Lead to 80% Power-Sector Carbon Reduction Continent-Wide by 2050
Steeper cost reduction of wind and solar technologies can lead to a faster and less costly transition, and carbon targets can still be achieved with conservative wind and solar cost assumptions. When it comes to total system costs of achieving 80% power-sector emissions reductions, wind and solar cost trajectories have a more significant impact than carbon policy assumptions.

“Transmission expansion benefits are higher with more electrification and more wind and solar, which is a trend that could continue in lower-carbon scenarios or longer-term futures,” said Josh Novacheck, NREL electricity system research engineer and coauthor of the study. “Transmission can also provide reliability benefits and enable exchanging load and renewable generation diversity between regions—during normal conditions as well as in extreme events.”

Finding 4: Operational Flexibility Comes From Transmission, Storage, and Flexible Operation of All Generator Types
The results show the future low-carbon power system will benefit from many different forms of operational flexibility. In the United States, this includes flexible operation of natural gas and hydropower, curtailment (i.e., purposeful reduction) of wind and solar generation, and storage (mostly pumped storage hydropower). International imports, enabled by transmission buildouts, also help to balance the grid.

In Canada, hydropower, wind, solar, and thermal generation are key sources of flexibility. On days when Canada has high energy demand but lower wind energy output, Canada imports electricity from the United States. For days with higher Canadian wind output, the Canadian grid exports electricity to the United States—even when electricity demand peaks in both countries in the evening.

Hydropower provides a zero-carbon source of energy, capacity, and flexibility to the grid. In comparing similar scenarios with and without the ability to adjust power output from U.S. and Canadian hydropower generators, annual system costs are $2.3 billion higher without this flexibility.

Forging a Path for Future Research
“In addition to highlighting several opportunities for a coordinated, continental low-carbon grid, NARIS created open-sourced data and methods for future studies to build on,” Novacheck said. “We also identified several priorities for future research to expand on our findings.”

Follow-on work could focus on studying the stability aspect of power system reliability, analyzing new scenarios that reflect today’s emissions reduction goals as well as technology costs, understanding the impact of different market structures on building new transmission and generation, and refining how we model electricity demand patterns and sources of flexibility under future widespread electrification.

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