Gridlock: Visualizing the U.S. Clean Energy Backlog

The U.S. has almost 2 million megawatts (MW) of solar, wind, and storage capacity on hold in interconnection queues, seeking connection to the electrical grid.

However, the lack of transmission infrastructure, in addition to a lengthy permitting process, has resulted in a bottleneck of clean energy projects awaiting approval before they can be plugged into the grid.

This infographic sponsored by the National Public Utilities Council maps U.S. clean energy capacity in interconnection queues by transmission region, based on data from the Berkeley Lab.

But before we dive into the data, let’s fully understand what interconnection queues mean.

What are Interconnection Queues?

Before new power plants can be built and connected to the grid, they go through a series of impact assessments to ensure safety and reliability. The projects in this process form grid interconnection queues, which are essentially waitlists of proposed power plants seeking grid connection.

Here are some of the problems associated with U.S. interconnection queues:

• Wait times: The average time projects spend in the queue is up from 2.1 years in 2000 to 3.7 years in 2021, according to the Energy Transitions Commission. 
• Withdrawal rates: Historically, most projects have withdrawn from the queue, with just 21% of projects seeking connection from 2000–2017 reaching commercial operation.
• Aging transmission: The U.S. grid is aging, and queued-up projects can end up facing large fees from the updates required to transmission infrastructure.

Although the backlog is alarming, the interconnection queues also show that project developers are invested in the clean energy transition. In fact, the amount of clean energy capacity in interconnection queues exceeds the amount needed to get to 90% zero-carbon electricity by 2035, according to Berkeley Lab.

U.S. Clean Energy in Queues

Solar and battery storage projects account for the majority of capacity in interconnection queues, followed by wind.

Data as of the end of 2022.

Notably, 48% of all solar capacity in the queues is proposed as a “hybrid plant” that combines generation with battery storage. Similarly, over half of all battery storage capacity is proposed with some amount of generation.

The large number of hybrid and storage configurations show that project developers are addressing the intermittent nature of renewables by combining generation with storage.

Interconnection queues are managed by Independent System Operators (ISOs) and Regional Transmission Organizations (RTOs) that operate the grid and wholesale electricity markets in different regions. Here’s a look at the clean energy capacity in queues grouped by major transmission regions and ISOs:

Data as of the end of 2022. Percentages may not add up to 100 due to rounding. 

Overall, the West (non-ISO) region has the most solar (254 GW), battery (262 GW), and onshore wind (63 GW) capacity in interconnection queues. Offshore wind capacity is highest in New York (63 GW), managed by the NYISO.

In 2022, California ISO did not accept any new interconnection requests due to the backlog from 2021. Meanwhile, the PJM announced that it would not review any new requests until 2025. Despite these slowdowns, over 700 GW of capacity was added to U.S. interconnection queues in 2022.

Unlocking the Gridlock

Given the current backlog, along with the incentives for new clean energy projects in the Inflation Reduction Act, clearing the gridlock is now more important than ever.

The large backlog, long wait times, and high withdrawal rates highlight the growing challenges in interconnection and transmission. Among other longer-term solutions, there are two ways to alleviate the gridlock:

• Expanding high-voltage transmission lines: Many solar and wind projects are located in remote areas and require high-voltage transmission lines to carry electricity to cities. Expanding the transmission network can allow more projects to connect to the grid.
• Streamlined permitting: Interconnection processes and the reviews involved are long and costly for project developers. Reforming processes and streamlining permits can help in shortening the wait times for projects in queues.

To address this problem, some grid operators have already made changes to their interconnection processes. Additionally, the Department of Energy has launched the Interconnection Innovation Exchange (i2X) in an effort to improve collaboration and transparency in interconnection.

History shows that most of the projects in interconnection queues will ultimately not be built. However, what’s clear is that the U.S. is on the road to decarbonization, and energy project developers are focusing on clean energy sources for the future.

Visualized: Clean Energy and Emissions Goals by State

In its Nationally Determined Contribution to the Paris Agreement, the U.S. set a target of reducing its greenhouse gas (GHG) emissions by 50-52% below 2005 levels by 2030, as well as achieving 100% carbon-free electricity by 2035.

To discover how each state is contributing to these goals, this graphic sponsored by the National Public Utilities Council provides an overview of each state’s ultimate clean energy or GHG emission reduction goal.

Varying Commitments

An analysis of the aggregated data by S&P Commodity Insights reveals a broad spectrum of clean energy and emission reduction goals in the United States.

While some states have more ambitious goals of attaining 100% clean energy by 2040, others, such as Ohio, have opted for more modest and short-term targets, aiming to achieve 8.5% renewable electricity by 2026.

Eleven states, or 22%, have never set clean energy or emission reduction goals. These states include Alabama, Florida, Georgia, Mississippi, Tennessee, and West Virginia.

Similarly, another ten states (20%) have expired goals with target dates as far back as 2015. These ten states, including the Dakotas, Missouri, Kansas, Montana, and Oklahoma, have not reset their goals since.

Shares of Clean Energy by State

To get a glimpse into how far each state has to go in achieving its goal, a snapshot of the use of clean electricity in each state is shown below.

Using data from the Nuclear Energy Insitute, the bars show each state’s 2021 share of emission-free electricity broken down by nuclear and various renewables.

While clean electricity made up 70% or more of the electricity mix in several states, nuclear and renewable energy sources comprised approximately 40% of total U.S. electricity generation in 2021.

To hit its 100% carbon-free electricity goal, therefore, the U.S. needs a minimum 4.3% annual increase in clean electricity generation through 2035. For context, an average annual growth of 2.4% was observed in the last five years.

On the GHG reduction side of things, emissions were 17% below 2005 levels in 2021, showing the need for an additional 35% reduction by 2030.

As these figures show, achieving the ambitious clean energy and emissions reduction goals in the U.S. will require a significant ramp-up of clean electricity generation in the upcoming years, along with accelerated decarbonization efforts across all sectors.

Click here to learn more about how electric utilities and the power sector can lead on the path toward decarbonization.