Strategic Technology Research Backgrounder
Advanced Materials; Delivery and End-Use
The Electric Power Research Institute, Inc. (EPRI) conducts research and development relating to the
generation, delivery and use of electricity for the benefit of the public.
With a staff of recognized industry experts, EPRI has established itself as a thought leader in the electric
sector worldwide. The organization is recognized for developing and demonstrating innovative
technologies, analyzing and enhancing current technologies, as well as seeking alternative methods to
produce and deliver electricity.
EPRI’s Technology Innovation (TI) organization has been integral in leading the development of key
technologies that have benefitted the electricity industry in numerous ways. The organization focuses on
stimulating innovation and developing enabling electricity technologies for adoption over a 5-10 year
period, or longer. For instance, EPRI research has lead to recognition of the global impact of mercury, the
development of a high-impact decontamination process and technologies to reduce carbon emissions
from coal generation.
The technology challenges that the electricity industry will face in achieving a low carbon future will
require groundbreaking technology development in a number of strategic areas. EPRI has identified 10
strategic programs that will be the focus of its longer term research efforts from 2009 and beyond. One of
the 10 is described here.
Advanced Materials; Delivery and End-Use
Current Situation
What is the current state of the art?
In many cases, materials that date to the first half of the 20th century remain in components on the power
delivery system. As equipment fails or reaches the end of its life, new equipment is installed that generally
employs incremental material improvement. An historical obstacle to widespread adoption of new
materials has been the long product cycles, 40 years or longer, of components on the power delivery
system.
The development of nano engineering and other advanced techniques has created new opportunities to
improve materials used in the transmission and distribution infrastructure. However, this materials
technology is new and unproven. Power electronics-based controllers are substantially improving control
over the grid, enabling increased power flow and enhancing reliability. However, present silicon-based
technologies used in these controllers are not sufficiently robust to be cost-effective in many applications.
Materials critical to the electric power enterprise have been found to be potentially damaging to the
environment. In some cases, no alternatives to these materials have been found, calling for effective
substitutes. Similarly, rising energy prices have opened the door to commercialization of new building
materials that can significantly enhance energy efficiency. Seed research funding is required to identify
which technologies can most cost-effectively be developed to meet market needs.
Why is EPRI investing in this area?
Today, various drivers are motivating more rapid adoption of equipment with advanced materials. Limited
investment in the power delivery system in recent decades has created a backlog of needed upgrades.
The widespread use of digital loads, such as microprocessor-based assembly lines or server farms, has
also placed new requirements on the power delivery system. Additionally, the advent of the “smart grid”
will help instigate infrastructure upgrades. Finally, accommodating carbon reduction technologies, such
as renewables, energy storage, demand response, and plug-in hybrid electric vehicles (PHEVs) across
the grid will also require making upgrades to components and devices with advanced materials.
The Opportunity
What are the potential superior innovations?
The electric power industry is nearing the point of a revolution in advanced materials technology.
Nanotechnology, which uses technology to manipulate matter at the nano-scale, is a central element in
this transformation. Today’s so-called “mild” nanotechnology, which includes about 90 percent of most
current nano-based research, involves manipulation of individual molecules within materials to improve
their properties, based on knowledge and understanding of the underlying science. Work in this area will
likely offer commercial products in 5-10 years. For example, dielectric materials that utilize nano-filler
materials promise breakthroughs in voltage endurance and breakdown strength for transmission and
distribution applications. Similar revolutionary improvements are possible with nano-based coatings, such
as in fiberglass transmission components. Longer-term nano-based efforts consist of forming completely
new materials and other advanced concepts such as self-replicating robots and molecular machines.
Power electronics devices such as static VAR compensators, solid-state circuit breakers, and solid-state
transformers, including EPRI concepts such as the Intelligent Universal Transformer, help enhance
control, reliability and flexibility of the power delivery network while reducing operations and maintenance
costs. However, most present-day power electronics are based on silicon semiconductors, which are
limited in terms of voltage, switching speed and temperature. Silicon carbide, when used as the base
material for power electronics devices, offers significantly higher breakdown strength, lower switching
losses and higher tolerance of high junction temperatures than silicon, making this material extremely
attractive for high-voltage power electronics devices.
Sulfur hexafluoride (SF6) is a stable, inert gas with high dielectric strength, making it an ideal gaseous
insulator. Its arc-quenching properties make it exemplary for use in circuit breakers. These properties
have led to extensive use of SF6 in breakers, switches and other high-voltage transmission equipment.
SF6 is also a powerful greenhouse gas, with one of the highest global warming potentials (GWP) among
known materials, at 22,200 times that of carbon dioxide over a 100 year horizon. Although the amount of
SF6 released to the atmosphere is relatively small, the high GWP figure and the long lifetime of the gas is
a cause for concern. Identification of a suitable replacement for this vital material with less environmental
impact would fundamentally change circuit breakers, switches and other high voltage equipment.
In power utilization, building heating and cooling loads remain a major opportunity for energy efficiency
savings. New materials for the building envelope could enable enormous improvement in the energy
efficiency of buildings, reducing power consumption without compromising comfort. Energy efficiency
reduces power consumption across the power delivery network, making resources available for other
loads and effectively increasing the value of electricity. New materials for the building envelope include
electrochromic coatings for windows, advanced building insulation, and cool roof technologies.
How could this research change the industry?
On the power delivery system, nano-composites promise to deliver higher breakdown strength and
greater voltage endurance than conventional dielectrics, enabling cables with smaller diameters to carry
the same power as larger cables. Nanotechnology also has the potential to improve the performance of
fiberglass components such as hotsticks, guy strain insulators, cross-arms and polymer insulators.
Potential improvements include resistance to scratching, abrasion, impact, water permeability, tracking,
2
as well as improved strength. This can be achieved by either using nano-based coatings or nano-based
epoxies.
Advanced power electronics devices based on silicon carbide and gallium nitride, rather than silicon
alone, can dramatically improve grid control, power flow and reliability. This means that congestion on
constrained transmission corridors could be relieved, possibly deferring the need for new transmission
construction. Advanced materials could help protect the environment, for example, by identifying an
alternative to the greenhouse gas sulfur hexafluoride in power delivery equipment. An array of broadly
deployed advanced materials could speed implementation of smart grid technologies and help the power
delivery infrastructure support carbon reducing technologies such as renewables, energy storage, PHEVs
and demand response. In power utilization, new materials for the building envelope may help building
owners improve energy efficiency and reduce power consumption.
What other applications are possible?
The development and implementation of nanotechnologies in the electricity sector are not limited to
power delivery and end use applications. Advances in materials that are being pursued in this program
have the potential to be cross-cutting, with applications in fossil and nuclear power generation and in
other aspects of power delivery, utilization and end-use.
The Program
How are innovations being developed?
The Materials –Delivery and End-Use program is designed to aggressively invest in early-stage materials
technologies that will be important for the future of the electric power enterprise, and by funding seed
research in materials areas that will be critical in the future. Five key projects are planned in this program:
1. Advanced Cable Dielectrics. EPRI has conducted research to investigate nano-composite dielectric
materials for underground transmission and distribution cables. While significant technical progress has
been made in this area, the resulting material remains in an early pre-prototype development stage, and
will not become commercial in less than five years. Significant mechanistic study is required in this area to
characterize the material and understand mechanisms of wear and failure.
This program will first address the scientific analysis of nano-composite dielectrics. The materials science
that is supporting the development of commercially viable nano-composite dielectrics is in its infancy.
Significant additional research, using sophisticated analysis tools, is required in several areas, including
the measurement of water-tree resistance of nano-composites (coupled with a study of physical
mechanisms of the same); characterization of the mechanical and thermal properties of nano-composite
dielectrics; and confirmation of electrical properties of manufactured pre-prototype cables. The program
will also perform cost/benefit tradeoffs between nano-composite dielectrics and conventional dielectrics,
as well as assess the impact of the technology on other aspects of underground distribution and
transmission system design and construction.
2. Advanced Power Electronics Materials and Devices. This project focuses on the development of
silicon carbide and gallium nitride power electronics components. EPRI has been funding ongoing
strategic research in the development of silicon carbide devices in a partnership with Silicon Power
Corporation (SPCO). Efforts will address development of larger dies, termination and packing design to
demonstrate prototypes, cost reduction, and new materials. Funding for the silicon carbide area is highly
leveraged with external funding from the U.S. Department of Defense and the U.S. Department of
Energy.
3
At high power levels, the control of power electronic switches is difficult because the control circuitry must
be physically wired to the device, making electrical isolation difficult. One method proposed to resolve this
problem is the use of optically sensitive switches that can be controlled or triggered by pulses of light.
Such devices have been manufactured using silicon, but suffer from the conventional limitations of silicon
devices, namely low breakdown voltages and poor high-temperature operation. Gallium nitride (GaN) has
been demonstrated to potentially resolve these limitations, enabling a cost-effective, optically-controlled
high-voltage switch. An initial EPRI scoping study will identify future directions for research. Subsequent
years will continue to expand research into GaN.
3. Nanocoating for Fiberglass Transmission Components. A 2008 EPRI project developed, applied,
tested and characterized a nano-based coating on test sections of fiberglass, and then assessed the
commercial viability of the test coating. The project team used test results to identify weaknesses in the
coating formulations and developed approaches to restructure coating components and precursors to
address them. Research in 2009 will include implementation of these approaches and further testing to
characterize coating behavior. The program will continue to engage vendors of fiberglass products and
utility users to ensure that maximum benefit for the industry is achieved.
4. Alternatives to Sulfur Hexafluoride. The goals of this project are to provide early identification,
qualification, testing, and development of suitable substitutes to sulfur hexafluoride that will ensure that
transmission systems will not be compromised by the absence of alternatives in the future.
5. Advanced Materials for Energy Efficiency. Electrochromic coatings change the transmittance of
windows with active control, allowing the user or an automated system to determine how much light and
at what wavelengths the window transmits. This can be used, for instance, to make the window opaque to
heating rays in the summer, reducing the cooling load, and then become transparent to the same rays in
the winter, taking advantage of the sun to heat the building. This approach allows more flexibility in use
than traditional reflective coatings, which reflect sunlight regardless of season and time of day.
Existing electrochromic windows are only economical in new construction. The development of thin-film
electrochromic coatings could allow retrofits of existing buildings without full replacement of the windows,
making the technology much more valuable. While such coatings have been shown to be possible, the
manufacturing hurdles are significant. This project will pursue these challenges.
Modern fiberglass and cellulose insulation materials in buildings reach up to R-49 insulation levels.
Advanced materials may reach even higher insulation levels and require less space. Many of these
materials have already been developed for special applications, such as military and space, and may
have potential for large-volume production and commercialization.
The research community has developed advanced roofing materials that reflect heat and allow buildings
to remain cool even during conditions of strong insolation, such as cool roof technology. However, these
materials may not meet market requirements of color or form factor. This project will attempt to push
these technologies towards the stage of commercialization.
Value
What are anticipated costs and benefits?
Advanced materials for power delivery applications may enhance power system control, and
increase power flow through constrained transmission corridors. These capabilities could help relieve
congestion and defer or avoid new transmission construction. Advanced materials incorporated into
power delivery equipment may help enhance power system reliability, improve power quality, and reduce
4
ongoing maintenance costs. New equipment will typically offer a longer life (e.g., 80 years instead of 40
years), helping to avoid future capital costs and enabling utilities to improve asset utilization. In some
cases, advanced materials could reduce environmental impacts such as alternatives to sulfur
hexafluoride. In total, incorporation of advanced materials into power delivery equipment could facilitate
widespread adoption of smart grid technologies and help accommodate carbon reducing technologies,
such as renewables, energy storage, PHEVs and demand response. In power utilization, advanced
materials can help to foster end-use energy efficiency, and may help to improve consumer satisfaction
with electric service via reduced energy costs and services to help install energy efficient equipment and
materials.
About EPRI
The Electric Power Research Institute, Inc. (EPRI, www.epri.com) conducts research and development
relating to the generation, delivery and use of electricity for the benefit of the public. An independent,
nonprofit organization, EPRI brings together experts from academia and industry as well as its own
scientists and engineers to help address challenges in electricity generation, delivery and use, including
health, safety and the environment. EPRI's members represent more than 90 percent of the electricity
generated and delivered in the United States, and international participation extends to 40 countries.
EPRI's principal offices and laboratories are located in Palo Alto, Calif.; Charlotte, N.C.; Knoxville, Tenn.;
and Lenox, Mass.
###
Contact:
Don Kintner
EPRI
Manager, Communications
dkintner@epri.com
704-595-2006
5