In The Value of Interregional Coordination and Transmission in Decarbonizing the US Electricity System, MIT researchers Patrick Brown and Audun Botterud show that the U.S. electricity system can be completely decarbonized using technologies currently being deployed at gigawatt-scale. The authors demonstrate that coordinating power system planning and dispatch across state and regional boundaries along with a doubling of installed transmission capacity substantially reduces the cost of zero-carbon electricity – by as much as 46% when comparing a nationally coordinated system to a state-by-state approach. The authors note that the doubling of transmission capacity would not require a similar increase in transmission-line-miles, as high capacity lines can carry 7.5 times more power than smaller lines over a given distance. The study also demonstrates that given a choice between low-cost flexible nuclear, long-duration storage, or low-cost renewables (wind and solar) and Li-ion batteries, low-cost renewables and batteries lead to the lowest electricity cost when transmission expansion is allowed.
Macrogrids in the Mainstream: An International Survey of Plans and Progress demonstrates the value of developing interregional transmission and macrogrids to inform US energy policy and engineering communities through a discussion of: (1) the global state of macrogrids, (2) the benefits, cost and characteristics of implementation, (3) engineering design, and (4) consolidating and coordinating mechanisms to accomplish interregional transmission. While a number of countries are considering the development of macrogrids, some have already begun to capture the opportunity to take steps to meet aggressive climate goals and to make their economies more globally competitive. China, for example, recently completed five times more high voltage transmission interconnections than Europe, and over 80 times more than the US.
In Consumer, Employment, and Environmental Benefits of Electricity Transmission Expansion in the Eastern U.S., firms Vibrant Clean Energy (VCE) and Grid Strategies show that transmission investments in the eastern United States can cost-effectively reduce electric sector CO2 emissions 95% by allowing the region to obtain over 80% of its electricity from wind and solar by 2050. The report shows that increased access to low-cost renewables brings average electric bill rates down by 3 cents/kWh, translating to more than $300 in annual household savings. Further, the study shows investments in transmission infrastructure will create 6 million net new jobs, increasing electric sector employment nearly 5-fold to more than 7.6 million over the next several decades.
The study evaluated four scenarios, with varying degrees of CO2 emission reductions and relative shares of wind and solar deployment. Many of the same transmission upgrades were built across all four scenarios, indicating these investments will be needed regardless of future wind and solar cost trends. The cost of transmission was less than half a cent per kWh in all scenarios, yet yielded savings many times greater than that. The model also used battery storage to increase the utilization of transmission lines, demonstrating that storage is a transmission complement, and not a substitute, as similar studies have found.
Grid Vision provides three key policy recommendations for realizing the benefits of an expanded transmission system. These three recommendations are centered around the “Three Ps” of Planning, Paying and Permitting, which call for forward-thinking and collaborative transmission planning, broad transmission cost allocation to reflect the broadly distributed benefits of transmission, and the simplification of interstate transmission line siting, respectively. Grid Vision concludes that expanding the current transmission system network could save consumers as much as $47 billion annually, a roughly 10 percent reduction in electric bills.
The National Renewable Energy Laboratory (NREL) conducted the Interconnections Seam Study to analyze the costs and benefits of optimized nationwide transmission expansion. The study develops four transmission designs with various levels of increased transmission capacity aimed at connecting the nation’s main grid regions. Each design scenario is analyzed under eight scenarios with different assumptions regarding transmission costs, renewable generation levels, wind and solar costs, gas prices, and generator retirements. Between 2024 and 2038, the analysis finds total transmission investment needed ranges from $40 billion under a base scenario to $101 billion under a high variable generation scenario where 39% of annual generation is composed of wind and solar. The study approximates cost-to-benefit ratios over a 35-year period to be as high as 2.9 under the high variable generation scenario.
North American Supergrid: Transforming Electricity Transmission is an initiative of the nonprofit Climate Institute that contemplates a North American Supergrid, or a largely underground, nationwide HVDC network that would extend across the lower 48 states, improving national security and enabling higher penetrations of cost-effective renewable energy. The study also examines the technical and engineering challenges with implementing a largely underground HVDC system, estimating such a network would create hundreds of thousands of jobs over several decades. Approximately two-thirds of the HVDC cable links in the proposed system can feasibly be placed underground along existing rights of way, greatly reducing the time and effort needed to move forward with permitting and construction, according to the report. Transmission investments necessary to construct the Supergrid over a 30-year time frame are estimated to total roughly under $500 billion, and would assist in reducing “business as usual” 2040 power sector sulfur dioxide and particulate matter emissions by a factor of approximately 7.
In Carbon-Neutral Pathways for the United States, the National Academies of Sciences, Engineering and Medicine offer eight different deep decarbonization scenarios with various levels of resource constraints, demand, and technology uptake that would allow the U.S. to reach net zero or net negative CO2 emissions by the year 2050. Gross emissions modeled in the central case scenario are estimated to total 840 Mt CO2 per year in 2050 – an 84% reduction from 2020 levels – and are achieved through the more efficient use of energy, the decarbonization of electricity, end-use fuel switching, and carbon capture technology deployment. The study demonstrates that a key piece of this transition to a low-carbon energy system involves the expansion of interregional transmission to reach geographically diverse generation and load profiles. The central case scenario estimates that expanding interregional transmission by 223 GW-miles – a 2.5-fold increase over 2020 transmission levels – would increase the share of wind and solar to 60% of total generation.
Net-Zero America: Potential Pathways, Infrastructure, and Impacts outlines five energy system pathways the U.S. can potentially choose to reach net zero emissions by the year 2050, alongside a number of priority actions needed by 2030 to assist in that transition. In a 100 percent renewable scenario, high voltage transmission is estimated to nearly double by 2030, increasing by 250,200 GW-km at a total cost of $390 billion. By 2050, total current transmission capacity quintuples, increasing by 1,382,100 GW-km at a cost of $3.7 trillion. By 2030, transmission expansion in most scenarios will facilitate up to 4 times the amount of wind and solar generation capacity currently available, which could supply roughly half of all U.S. electricity demand. By 2050, transmission expansion could allow wind and solar resources to supply up to 98% of all U.S. electricity demand in a 100 percent renewable scenario.
Future Cost-Competitive Electricity Systems and Their Impact on US CO2 Emissions, funded by the National Oceanic and Atmospheric Administration and published in the Nature Climate Change journal, models the benefits of constructing a nationwide HVDC transmission network designed to tap into renewable and other low-carbon resources geographically dispersed throughout the country. Under such a network design, approximately 60 percent of U.S. power sector electricity could be generated from wind and solar resources alone. The study analyzes the emission reduction potential of the transmission network shown above under three scenarios:
With new HVDC lines to access resources more efficiently, the HRLG, MRMG and LRHG scenarios are expected to reduce power sector emissions by 33 percent, 61 percent, and 78 percent, respectively, compared to 1990 levels. Additionally, consumers are expected to save as much as $47.2 billion annually under the LRHG scenario, which is roughly the equivalent of a 10 percent reduction in electric bills or roughly three times the cost of the HVDC transmission builds per year.
Disconnected: The Need for a New Generator Interconnection Policy, a report sponsored by Americans for a Clean Energy Grid on behalf of the Macro Grid Initiative, examines the interconnection process and finds that policies governing queues are unworkable and inefficient, having resulted in a backlog of 734 gigawatts of proposed generation — 90 percent of which are new wind, solar, and storage projects. The report finds that this backlog has increased electricity costs for consumers, harmed rural economic development and job creation efforts, prevented states, utilities, and businesses from reaching their decarbonization goals, and needlessly exposed Americans, especially those in marginalized communities, to the harmful impacts of smog, nitrogen oxide, sulfur oxide, fine particulate matter, and carbon dioxide pollution. The paper calls for FERC to discontinue the current “participant funding” policy, labeling a model that places nearly all costs of shared network upgrades on interconnection customers to be no longer “just and reasonable.” The report recommends that FERC and RTO planning authorities expand and improve regional and interregional transmission planning processes to proactively incorporate future generation additions, retirements, and benefits to load, while spreading the costs of upgrades that provide economic and reliability benefits and reduce congestion to all beneficiaries.
The Eastern Interconnection Planning Collaborative (EIPC), funded by the U.S. Department of Energy, released a two-phase study assessing future power sector infrastructure needs across the Eastern Interconnection. Phase II of the study developed transmission expansion buildouts for three future scenarios selected from a larger set of eight scenarios identified in Phase I. The three scenarios include (1) a nationally-implemented federal carbon constraint with increased energy efficiency and demand response, (2) a regionally implemented national renewable portfolio standard, and (3) a business as usual future. Between 2015 and 2030, transmission expansion for scenarios 1 and 2 is estimated to cost up to $115 and $80 billion, respectively, with annual operating cost savings corresponding to $52.6 billion and $9.7 billion, respectively. This indicates that Scenario 1, with national policy and transmission expansion, provides large net benefits relative to Scenario 2’s regional solutions and Scenario 3’s business as usual scenario.
The U.S. Department of Energy’s (DOE) Wind and Water Power Technologies Office conducted the Wind Vision study to evaluate future pathways for wind power to meet US electricity needs and decarbonization goals. As part of the study, DOE models a Baseline Scenario with US wind capacity held constant at 2013 levels of 61 gigawatts, a Business-as-Usual Scenario (BAU), and a Study Scenario. The Study Scenario, which is the primary analysis scenario, evaluates the costs, benefits, and other impacts associated with a pathway through which wind energy is able to meet 10%, 20%, and 35% of the nation’s end-use demand by 2020, 2030, and 2050, respectively. Incremental transmission-related expenditures of the Study Scenario are estimated to total $60 billion compared to the Baseline Scenario. The many benefits afforded by high levels wind penetration facilitated by the transmission expansion modeled in the study includes, among other things, cumulative system cost savings of $149 billion by 2050, 12.3 gigatonnes of avoided GHG emissions through 2050, and quantified consumer cost savings of $280 billion through 2050.
In its Report on Barriers and Opportunities for High Voltage Transmission, the Federal Energy Regulatory Commission (FERC) provides a strong endorsement of large-scale transmission, stating that, “high voltage transmission can improve the reliability and resilience of the transmission system by allowing utilities to share generating resources, enhance the stability of the existing transmission system, aid with restoration and recovery after an event, and improve frequency response and ancillary services throughout the existing system.” The report notes that it is estimated the US will require between $3 and $7 billion in additional annual transmission investment through the year 2030 to meet electrification needs, beyond the investments necessary to maintain the existing transmission system and integrate renewable resources. FERC also touted the climate benefits of transmission, highlighting that “transmission can help states achieve their renewable portfolio standards (RPSs) and renewable portfolio goals” and that “high voltage transmission can help states achieve their greenhouse-gas emission reduction targets” by increasing the availability of carbon-free energy and facilitating the replacement of fossil fuels. FERC also found that “transmission investments improve competition in wholesale markets by reducing congestion and allowing the lowest-cost resources to compete.” In the report, FERC also examined opportunities for future transmission expansion, including the co-location of transmission along existing rights of way, such as railroads or highways, noting that “co-location of transmission in transportation corridors could reduce both the negative effects caused by a project and the cost of project development.”
Informing the Transmission Discussion offers an overview of the challenges each US region faces as a result of changing energy mixes, increases in electrification, increases in demand-side variability from DERs and energy storage and the need for location-constrained renewables. The study looks at the current regional transmission landscape and examines what must be done to address these challenges, finding that transmission is a critical solution for meeting both clean energy and resilience objectives. Informing the Transmission Discussion also details how the electrification of buildings and vehicles will increase demand for electricity supply and renewable resources, with an estimated $7 to $25 billion in transmission investment needed by 2031 to meet these needs.
Minnesota’s Smarter Grid, a study performed by Vibrant Clean Energy, models eight future Eastern Interconnection electric system scenarios to determine the optimal pathways through which Minnesota can meet its state goal of decarbonizing its economy 80 percent from 2005 levels by 2050 (80×50). A more flexible grid with increased interstate transmission can efficiently support the large amount of renewable resources needed to meet decarbonization goals while providing service at costs lower than current costs and costs incurred through a lack of interstate transmission. The study finds that scenarios with interstate transmission expansion can introduce annual savings to Minnesota consumers of up to $2.8 billion, with an annual savings for Minnesotan households of up to $1,165 per year.
New Jersey’s Integrated Energy Plan, commissioned by the state’s Board of Public Utilities and based on analysis by the Rocky Mountain Institute, finds that existing New Jersey policies will not be sufficient to meet the state’s clean energy goals. Modeling of the least-cost pathways to meet these goals finds that PJM-to-New Jersey transmission will need to be increased from 7 to 9 gigawatts in order to achieve the state’s 100 percent carbon-neutral by 2050 target. This enhanced transmission capacity, which will cost roughly under $20 billion between 2030 and 2050, will allow New Jersey to cost-effectively import electricity from new out-of-state wind and solar plants.