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Electricity Delivery System Applications (CABLE)

Description:

b.      Electricity Delivery System Applications (CABLE)

This subtopic solicits innovative research and development (R&D) proposals that can enable breakthrough applications to better secure the national grid and make efficiency and affordability improvements to electricity delivery system (EDS) infrastructure. This subtopic is being jointly supported by the Office of Electricity and the EERE Advanced Manufacturing Office.

 

The U.S. electricity delivery system is currently undergoing a transformation as the importance of grid reliability and resilience is realized in the face of evolving threats (including cyber-attacks and extreme weather), and state and local policies increase penetration of renewable energy and distributed energy resources (DERs). To ensure reliable and secure electricity delivery in the future grid through these changes, technological advancements in transmission & distribution (T&D) infrastructure must be made [1]. Specifically, improvements are required in T&D infrastructure, and at their most fundamental, the material that transports power: conductors, and their application in transmission cables.

 

This subtopic seeks proposals to integrate affordable high-performance conductors into transmission and distribution applications to provide numerous benefits to EDS and other power-carrying applications (including overhead, underground and underwater cables). Lines or cables with significantly improved conductivity yield transmission benefits including minimized losses, increased strength, reduced sag and improved carrying capacity, all of which improve performance and operations. Improved-performance conductors promise immense benefits to all system stakeholders [2]. To the grid operator, the benefits from installing advanced lines and cables include increased grid reliability and resilience. To the customer, use of such lines and cables results in significant cost savings.

 

The primary goal of this subtopic is to design a proof-of-concept conductor for medium- to long- distance transmission lines and cables. In performing this design research, both desired properties and design specifications must be considered.

 

Desired properties of conductors for EDS applications include [3]:

·         Low resistance to minimize electricity loss.

·         Improved mechanical strength for maximized reliability.

o   Improved tensile strength.

o   Improved mechanical bend fatigue performance.

·         Improved thermal conductivity.

·         Improved melting points to maintain high operational strength.

·         High ductility for mechanical flexibility.

·         Earth-abundant content for minimized cost.

·         Recyclable and safe material end-of-life.

 

Maximizing one or several of these properties in the proposed conductor design is a priority of this subtopic. In addition, proposals to this subtopic must explain how they support OE’s goals for innovative transmission reliability, resilient distribution systems, energy storage, and advanced grid components. Proposals are encouraged to draw upon AMO-sponsored innovations in advanced material manufacturing, particularly for high performance conductors. Advanced manufacturing approaches such as additive manufacturing and roll-to-roll are encouraged where appropriate.

 

Use of a breakthrough in one property must be complemented by maintaining the other properties above minimum accepted values, with minimum standards described in each area of interest below. This is to balance a “breakthrough, leapfrog” improvement with minimums that support applicability and future commercialization. Expected improvements in metrics and how the improvements compare to the current state of the art must be clearly stated in proposals in response to this subtopic. Designs should maximize economic performance, demonstrate financial viability, and establish a credible pathway to commercialization.

 

A related consideration is meeting external design parameters. Rural utilities and co-operatives generally rely on USDA Rural Utility Service (RUS) specifications (and minimum accepted values) for designing and implementing electric infrastructure in their jurisdiction. Designing conductors that may be used in these areas removes one barrier from future commercialization potential. Properties of interest in these standards are more practical for the electric delivery application and include:

·         Operating voltage

·         Line current

·         Conductor Size

·         Max operating temperature

·         Line voltage drop

·         Power losses

 

The specific standards may be found at: https://www.rd.usda.gov/files/UEP_Bulletin_1724E-200.pdf [4]. The linked standards detail aboveground cables specifically, but RUS also publishes standards for other applications, including underground cables. Following federal standards in designing these conductors may benefit future commercialization opportunities and will make the project more appealing to a wider market. While it is not strictly required to meet any specific set of RUS standards, or every single standard in this research, keeping them in mind while designing an advanced conductor proof-of-concept will be favorably viewed by reviewers.

 

Areas of interest for this topic include:

1. Aluminum-Based Conductors: Aluminum is primarily used for overhead transmission lines, as it provides high-conductivity and light-weight benefits for low cost. The most common aluminum-based conductors are aluminum conductor steel reinforced (ACSR), but other on-the-market options include ACCC, ACCR, and ACSS. As a material, aluminum has potential for overhead lines, and advanced manufacturing methods may yield unique advancements for aluminum-based conductors [5]. Table 1 describes desired minimum values for several properties of the proof-of-concept aluminum-based conductor. Due to the variable nature of properties of differently sized conductors, precise values may change depending on size and ampacity chosen of the conductor design. As stated earlier, these thresholds are approximate guidelines for property thresholds to maximize commercialization potential in the future; it is expected that the design meets CABLE goals with an affordable, breakthrough, and leapfrog design.

 

Property

Desired Threshold

Notes

Electrical conductivity

> 62% IACS

 

Mechanical strength

Comparable to or stronger than that of on-the-market ACSR

Precise value may change depending on line rating

Resistance

< 0.2 Ω/1000ft

DC at 20°C

Ductility

Comparable to or stronger than that of on-the-market ACSR

Precise value may change depending on line rating

Cost

Should not exceed $2/foot finished product

May be substantially lower depending on line rating and manufacturing methods

 

2. Copper-Based Conductors: Copper-based conductors benefit from high conductivity and high strength but suffer from higher weight and costs. For medium- to long- distance transmission, these properties may make copper apt for underground or underwater applications, because the higher conductivity and strength increase reliability and efficiency. Aluminum-based conductors are by far the most common conductors for transmission applications, and thus there are fewer preferred requirements for a copper-based conductor. The proposed design should achieve over 100% IACS and must display viable application for undersea or underground cabling. Of utmost importance are minimizing cost while maximizing strength and conductivity. Discussing demonstrated viability for transmission application that may lead to future commercialization will help in the proposal.

 

3. Other EDS Applications: Not limited to strictly aluminum-based or copper-based conductors, there are other advanced technologies that support the specific goals of CABLE while bringing benefit to EDS. Proposals will be considered in the following areas. Adherence to standards and demonstrated grid-scale viability is essential to maintaining a strong application.

·         Aluminum/ Copper composite materials

·         Other conductor materials or cable designs that align with CABLE goals

·         Grid-viable projects that support advanced materials integration into transmission infrastructure. This may include:

·         Grid resilience and reliability innovations

·         Advanced insulating materials for high-voltage application

·         Conductor coatings for harsh conditions

 

This subtopic supports the Grid Modernization crosscut, emphasizing advancements for future grid architecture and technologies.

 

Questions – Contact: Benjamin Shrager, Office of Electricity, Benjamin.shrager@hq.doe.gov

 

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