The Department of Energy (DOE) has initiated a new “enabling” pathway to achieve and sustain a dramatic transformation of the nation’s evolving grid—through its power electronics fabric, with the realization of advanced semiconductor materials, devices, and power module technologies.
The agency on Nov. 21 unveiled the agency’s first awards—$42 million for 15 projects across 11 states—under the ULTRAFAST program, an Advanced Research Projects Agency-Energy (ARPA-E) initiative launched in February 2023. Dedicated to advancing semiconductor material, devices, and power module levels, a key program objective of ULTRAFAST (Unlocking Lasting Transformative Resiliency Advances by Faster Actuation of power Semiconductor Technologies) is to enable faster switching and triggering at higher current and voltage levels for improved control and protection of the grid.
While the “bottom-up” approach to advance “low-level” grid components stands in stark contrast with the DOE’s recently announced high-profile and multi-billion-dollar efforts to address evolving generation, transmission, and distribution gaps, ULTRAFAST’s first projects are geared to transform power management and control on the grid as well as enable future autonomous power distribution systems.
“Modernizing our nation’s aging power grid is critical to strengthening our national and energy security, and absolutely essential to reaching President Biden’s ambitious goal of a net-zero economy by 2050,” U.S. Secretary of Energy Jennifer Granholm told POWER in an emailed statement. “This new investment will support project teams across the country as they develop the innovative technologies we need to strengthen our grid security and bring reliable clean electricity to more families and businesses—all while combatting the climate crisis.”
Crucial But Unseen Grid Components: Power Electronics
As an ULTRAFAST program director explained to POWER, at the heart of the challenge is that the U.S. electric grid’s infrastructure is more than 60 years old. The grid is also increasingly confronted by a growing set of risks, including an increasing frequency of severe weather events, cyber and physical threats, but it must also withstand emerging threats like electromagnetic pulses and space-weather events. As the energy transition unfolds, the grid faces further complexities owing to electrification, which is poised to dramatically ramp up demand, and increased shares of distributed energy resources (DERs) and intermittent renewables.
However, the grid’s capacity to flexibly satisfy new demands has been conventionally limited by its regulation capabilities. At high and medium voltage (H/MV) levels, power flows are today mostly routed by substations, which rely on conventional electromechanical gear, low-frequency transformers, and slow protection equipment. The reaction times of these components can span several line cycles. That limits the grid’s ability to control, absorb, reroute, and isolate power flows—posing significant risks and vulnerabilities, including for cascading power failures, the DOE says.
Over the decades, innovations have furnished industry with more agile power electronics systems that have improved controllability, performance, and energy availability at a specific electronic interface. Power electronics, which typically sit between the grid and power sources or the grid and points of consumption, perform the crucial function of controlling and processing high voltages and currents to deliver power that supports various needs.
On the grid level, power electronics–based interfaces typically consist of modules made up of semiconductor-driven or semiconductor-controlled devices. A semiconductor switching device “is a key element of any power electronic system, which determines the frequency and power level of operation, as well as a significant portion of the converter loss,” the DOE explains. These devices control the flow of electrical current and voltage, for example, converting AC to DC, DC to AC, or changing voltage levels and frequencies within the same current type. Examples include solid-state transformers, fault current limiters, high-voltage direct current (HVDC), and power flow controllers.
For now, the DOE expects a dramatic ramp-up in the utilization of power electronics-based interfaces. By 2030, it suggests 80% of the grid’s power could flow through power electronics. It also notes power electronics are already replacing traditional thermal, mechanical, hydraulic, and pneumatic systems in other applications, such as electric cars, ships, and airplanes. The inclusion of power electronics in a multitude of new areas is “driven by gains in performance, efficiency, and reliability, in concert with reductions in size, weight, and operational costs,” it says.
Power electronic conversion systems show significant promise for the grid, too, given they are capable of “decoupling dynamics between system sources, distribution, and loads while improving system controllability, reliability, resilience, and efficiency,” the agency adds. The potential flexibility, control, and efficiency gained from power electronics interface advances could also potentially minimize the required transmission and distribution level needed to achieve net-zero goals by 2050, it says.
A New Approach to Enable Grid Agility and Performance
However, realizing benefits for grid applications will require new approaches that emphasize performance gains—such as the operation of voltages and currents at H/MV levels—and faster actuation speeds, which could, in turn, enable better control and protection methods while reducing converter sizes and power consumption, the DOE underscores.
A key sticking point today is that silicon has been the semiconductor material of choice for power devices owing to cost, fabrication, and process maturity. But silicon devices are reaching their operational limits in blocking voltage capability, temperature of operation, and switching frequency due to silicon’s intrinsic material properties, which are limited by a low bandgap and critical electrical field.
“Current [silicon] devices cannot reach the current and voltage levels required by H/MV grid applications, requiring series and/or parallel stacking of multiple devices in multi-level modules. This poses challenges to reliability and introduces additional complexity and cost due to increased part count,” the DOE noted.
In February, ARPA-E launched ULTRAFAST to address this hurdle. ULTRAFAST aims to foster projects that will “create faster-switching higher-rated device and power module technologies.” As part of its purview, the program will seek to improve ultra-fast semiconductor devices and modules that could target protection functions at high current and voltage levels by achieving very fast by-pass, shunt, or interrupt capabilities, as well as high switching frequency devices and modules that could enable high-power, high-speed power electronics converters.
An agency program director told POWER that a key ULTRAFAST objective is to advance the performance limits of silicon, wide bandgap (WBG), and ultra-wide bandgap (UWBG) semiconductor devices. The development of WBG semiconductors (silicon carbide and gallium nitride) and UWBG semiconductors (aluminum gallium nitride, diamond, gallium oxide, and boron nitride) pose promising new opportunities for higher-performing devices, the official said.
These semiconductors “have superior electrical and thermal characteristics … that can circumvent the material limits of [silicon] and offer attractive alternatives for realization of power devices for grid applications,” the DOE says. A big draw is that these semiconductors could enable thinner, more highly doped voltage-blocking layers, which could reduce on-resistance “by an order of magnitude” in majority carrier architectures relative to equivalent silicon devices.
“The properties of the WBG and UWBG semiconductors permit devices to operate at much higher voltages, frequencies, and temperatures, providing a pathway to a more efficient, lighter, smaller, and higher temperature capable power electronics for H/MV grid applications,” it says.
However, WBG and UWBG materials development are still “relatively immature and still at a nascent stage,” it acknowledges. UWBG, in particular, has suffered “significant challenges, for example, difficulty with doping, material quality, cost, and consequently manufacturability.”
Another important ULTRAFAST R&D objective is to develop and demonstrate wireless sensing of voltage and current, high-density packaging with integrated wireless actuators and device/module-level protection, power cell-level capacitors and inductors, and thermal management strategies. When voltage is switched from higher voltages and faster currents, electromagnetic interference is generated that can interfere with the function of adjacent devices, an ULTRAFAST director explained. That has conventionally limited the ability to electronically control multiple devices arranged in a series or parallel combinations.
The official said that the idea of “optical control” and other wireless control could eliminate the wires and electromagnetic interference, which has so far prevented operation at higher voltage and the quick switching of currents.
Proposed Innovations Focus on Grid Control, Efficiency, and Protection
The DOE’s awards unveiled on Tuesday address several ULTRAFAST R&D objectives. The agency’s highest award—$3.1 million—will go to a project by the University of California, Santa Barbara, focusing on developing UWBG switching devices to achieve higher voltages and speeds than current technologies, enabling more advanced control methods for the grid. Texas Tech University will separately focus on a photoconductive semiconductor switching device using advanced UWBG materials.
Meanwhile, projects led by GaNify, Georgia Institute of Technology, and Lawrence Livermore National Laboratory will develop advanced semiconductor devices, enhancing power electronics converters’ control and efficiency for a more reliable grid. This includes innovations in WBG materials like III-Nitride. Michigan-based firm Great Lakes Crystal Technologies will separately develop a diamond semiconductor transistor to support DERs and variable load integration.
Opcondys, Sandia National Laboratories, and the University of Wisconsin-Madison will pursue projects concentrating on grid protection against transient surges and electromagnetic pulses, employing light-controlled devices and solid-state surge arresters for improved grid resilience.
Several other projects will explore the development of optically triggered technologies. A vital feature enabled by optical triggering is independent control of device voltage and current slew rates (switching transitions) achieved via a simple optical modulation, ULTRAFAST told POWER. According to the DOE, Lawrence Livermore National Laboratory, University of Illinois at Urbana-Champaign, NextWatt, University of Wisconsin-Madison, and University of Pennsylvania are developing optically triggered semiconductor transistors and UWBG optical devices.
Finally, the University of Tennessee will develop scalable “light-triggered” semiconductor switching modules with integrated sensing for grid protection, while Connecticut-based RTX Technology Research Center will develop semiconductor switching modules that are triggered by wireless radio frequency signals.
Timeframe and Deployment
According to ULTRAFAST, the project awards will span three years. While the DOE is pursuing a “portfolio” approach under the ULTRAFAST program, an official suggested that if all goes well, some awardees may be poised to achieve an initial demonstration of functionality within the project timeframe. Awardees are already talking to utilities and industry stakeholders, the official noted.
However, as with most first-of-their-kind technologies, their eventual commercial uptake may be more gradual. Cost poses the biggest obvious hurdle, the official said, noting that nothing new is ever cheaper.
In the semiconductor space, in particular, volume drives down cost, the official noted. While WBG materials like silicon carbide and gallium nitride are currently more expensive than silicon,—and UWBG materials are even more costly than WBG materials—the growth rate of these materials gives the DOE hope that they will reach cost parity, the official said.
Aside from the cost hurdles, the official noted WBG and UWBG materials will need to overcome material maturity. Because this has posed investment risks, the official noted that ARPA-E’s R&D efforts to explore the “enabling” technologies and potentially lead them through commercialization under a federal program are especially significant.