Integrating 100% Clean Energy Into the Electric Grid Infrastructure

By Julia Matevosyan

Integrating 100% Clean Energy Into the Electric Grid Infrastructure

ESIG’s conceptual design for a U.S. macro grid laid over the existing electricity transmission system. © ESIG

The Energy Systems Integration Group (ESIG) is a nonprofit association that convenes experts throughout the electricity industry’s technical community to tackle the central challenges of the transition to a high-renewables grid. ESIG’s members include utilities, regulators, system operators, equipment manufacturers, research organizations, and others. The organization creates a unique open and trusted environment where industry members can share their perspectives and collaboratively develop economic, reliable and sustainable solutions to energy systems integration.

The shift from large, conventional power plants and toward renewable energy poses some very interesting challenges regarding how a new resource mix meets demand as well as how grid reliability is maintained—technical challenges on which several ESIG working groups are focused. Major areas of work include transmission planning—bringing solar and wind energy from where the best resource potential is to where it will be consumed—hybrid resources, which can pair generation and storage, and market and operational changes needed for renewable energy to play an integral role in electricity markets and take on greater responsibility to support grid reliability. Recent initiatives undertaken by ESIG and its members are outlined below and discussed in a series of articles in the Nov/Dec issue of IEEE Power and Energy Magazine for which Charlie Smith, the Executive Director of ESIG, and Debra Lew, Associate Director, served as
guest editors.

Expanding Nationwide Transmission Infrastructure to Share Solar and Wind Production Across Regions

As the United States proceeds toward decarbonization, significant geographical pockets of wind and solar resources are being built in remote areas that have the best resource potential but are far from urban centers. The lack of transmission capacity to deliver this cheap and clean energy to where it’s needed has led to long interconnection queues where more than 600 GW of generation and storage projects wait months or years to be able to interconnect. ESIG’s white paper, Transmission Planning for 100% Clean Electricity, synthesized key research studies and developed a conceptual design for reaching the United States’ clean energy goals more quickly and affordably through proactive transmission planning and development. This Technical Brief outlines ESIG’s recommendations and summarizes engineering analyses that will be needed to refine the design and support the construction of a U.S. macro grid. Scope Development for Macrogrid Design Studies describes the general contours of the overall study effort and provides additional detail about the individual study elements.

Using Hybrid Resources to Enhance the Value Provided by Solar

Hybrid resources combine multiple types of generation and/or load that interconnect to the grid at a single point—today, this often means solar plus storage. The addition of battery storage to a solar plant enhances the value of solar resources, allowing it to charge batteries during periods when region-wide solar production is high and shift energy provision to the evening hours. While solar + storage is the most common type of hybrid today, ultimately, market design and regulatory requirements should allow for hybridization across many new types of resources and technologies. ESIG’s report Unlocking the Flexibility of Hybrid Resources describes what hybrid resources are, discusses why the industry is seeing increasing hybridization across technology types, and provides recommendations for system planners, market designers, and policymakers as they define market rules and requirements that govern hybrids’ use.

Identifying the Functionality Needed in Advanced (Grid-Forming) Inverters

The inverters used for nearly all currently deployed solar, wind, and battery storage resources require stable grid frequency and voltage, which is maintained today by conventional power plants. But as levels of renewables rise and conventional plants retire, some inverters will need to have new advanced controls (termed “grid-forming”) in order to themselves maintain system stability. However,
the specific requirements for these advanced controls are not yet defined, leading to a chicken-and-egg problem for system operators, equipment owners, and manufacturers: Which comes first, the requirement for a capability or the capability itself? How do grid operators know what performance is possible from new equipment? What drives manufacturers to invest in new technology without it being mandated or otherwise incentivized by the market? Failure to break this cycle will hinder our ability to meet energy transition targets and increase the cost. ESIG’s report on The Role of Grid-Forming Technology in Energy Systems Integration discusses what advanced controls are needed and describes a path forward for defining and incentivizing the appropriate functionality.

Integrating Distributed Energy Resources into Wholesale Markets

Distributed energy resources (DERs), such as rooftop solar, electric vehicle charging, or a battery connected to the distribution system, can offer a range of electricity system benefits; however, much closer coordination between electricity distribution and transmission systems is needed to make this happen. Without such coordination, electricity systems risk being over- or underbuilt and will be increasingly challenging to operate, leading to high costs and potentially lower reliability. Moving toward this more coordinated grid will require better integrating DERs into wholesale markets and operations as well as into distribution system operations. ESIG’s report, DER Integration into Wholesale Markets and Operations, examines the changes in regulation, market rules, and operating practices needed to do this.

Redefining Resource Adequacy

It is critical that power system planners, policymakers, and regulators continue to balance the three pillars of power system planning: affordability, sustainability, and reliability. Each one
is critical to ensuring a smooth, clean energy transition. One dimension of grid reliability is resource adequacy: having enough resources available to the system operator to meet projected future load, while accounting for uncertainty in both generation and load. The increased role of wind, solar, storage, and load flexibility requires the industry to rethink reliability planning, resource adequacy methods, and analytical approaches. The confluence of changes requires new data, methods, and metrics to better characterize evolving reliability risks. ESIG’s report, Redefining Resource Adequacy for Modern Power Systems identifies gaps in existing resource adequacy assessment methods and metrics and makes recommendations toward improving the analysis. ESIG also developed a COP26 policy brief The Intersection of Resource Adequacy and Public Policy that summarizes recommendations for use by policymakers.

About the Author
Julia Matevosyan is Chief Engineer of the Energy Systems Integration Group (ESIG) with more than 20 years of experience in the power industry. Prior to joining ESIG, Matevosyan was the Lead Planning Engineer of the Electric Reliability Council of Texas (ERCOT).

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