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Lang Tong is Building Intelligence into Energy Management
It’s going to take a lot of energy to power the country and the world through the next decade, let alone the next century or beyond. Light bulbs, electric cars, city power grids—the energy has to come from somewhere, and it has to be delivered with levels of efficiency, reliability, and resilience that are currently out of reach.
Lang Tong, the Irwin and Joan Jacobs professor of engineering at Cornell University, is trained as an engineer, but he’s taking a wide-ranging approach to energy that draws on economic theories as well as ohms and resistors. With the support of a new $1.4 million ARPA-E grant from the U.S. Department of Energy, he’s working with Khurram Afridi, associate professor of electrical and computer engineering, and assistant professor Francesco Monticone to explore new technologies to wirelessly charge electric vehicles as they speed down the highway, a potentially crucial step to a more sustainable future.
The explosive growth of electric vehicles promises to bring new challenges to the grid, Tong says. He notes that such vehicles were practically non-existent just a decade ago, but they could soon account for 20% of new purchases. “If every house has an electric car, that would be one of the biggest sources of energy consumption,” he says. “It’s one of the most interesting aspects of the future of the power grid.”
The ARPA-E project, “Field-focused load-leveled dynamic wireless charging system for electric vehicles,” could make it more feasible to power the electric vehicle revolution without overloading the grid, says Afridi, the project leader.
Afridi explains that most people today charge electric vehicles in the evening when they come home from work, putting a simultaneous strain on the system at a time of day when the sun is not providing much power. If charging systems were embedded within the road, vehicles could be powered on demand. “Essentially the car is receiving continuous, constant power,” Afridi says. “You’re cruising on the energy from the system instead of storing it. It’s almost like an electric railway.”
Tong’s role in the project is to develop artificial intelligence tools to ensure that wirelessly charged vehicles would draw a relatively constant load from the grid. Afridi and Monticone are working on daunting technical details. The proposed technology would use high-frequency electric fields to deliver 50 KW of power over a distance of 12 cm, which is roughly the clearance of a typical electric car. Afridi’s lab has already developed a prototype system that can deliver 2.5 KW over that distance; scaling that power by a factor of 20 will be a major challenge and, hopefully, a significant milestone.
Afridi notes that when he started investigating this sort of technology in 2014, the best anyone could do was deliver 5 W of power over 1 mm of distance to wirelessly charge cell phones.
Monticone’s main task is figuring out a way to keep the electricity confined to the charging pad and the engine, not shooting out the sides of the car or, worse, into the passengers. “It’s crucial to direct the fields—and the energy they carry—in the desired direction,” he says. To accomplish that, he plans to design a new type of charging plate using patterned metal sheets. “It will allow us to 'sculpt’ the electric field between the charging plates, making the wireless energy delivery most efficient,” he says.
If successful, such technology could greatly reduce the need for batteries while increasing the range and efficiency of electric vehicles. For electric vehicles to be broadly adopted, however, the electric grid has to be modernized.
“The transportation system and the electric power system consume two-thirds of total energy,” Tong says. “Merging these two would represent a huge infrastructure challenge. You would either have to build new power plants or tap into renewables. The only way that electrified transportation contributes to decarbonization and climate change mitigation is if the power for the car comes from clean energy.”
There are enormous technical and economic challenges in integrating solar and wind power everywhere to meet the emerging power demand from electrified transportation. To this end, Tong says, implementing smart digital technology is the key. Along with smart homes that manage energy consumption to match the lifestyle of residents, we need a smart power grid that integrates efficiently and reliably distributed energy resources such as the rooftop solar, behind-the-meter battery, and smart EV charging at home, in public parking facilities, and mobile charging on the road.
Tong has come a long way from his earlier career as a researcher. When he joined Cornell, he worked on wireless communications and networking. Making communications possible anytime and anywhere was the goal. While the science and engineering of wireless communications are compelling, the social and societal impacts of such ubiquitous communications have become more complex.
During a sabbatical at UC Berkely in 2008, Tong decided to devote his research effort to renewable energy. Over the past 14 years, his Digital Energy and Power System group has endeavored to make anytime anywhere renewable integration a reality by focusing on three pillars of smart grid technology: system optimizations under uncertainty, data analytics and machine learning, and engineering economics of renewable energy. From wireless communications to wireless charging with renewable energy, Tong says, electrical engineers will play a critical role in the energy transformation we will see in the 21st century.
Top: Lang Tong, the Irwin and Joan Jacobs Professor of Engineering. Photo by Eric Laine.