The UC Merced mechanical engineer has turned a penchant for systems-level thinking and a longtime love of cars into a climate-resilient research mission.
The future is electric.
From electric vehicles (EVs) traversing San Francisco’s busiest streets to electric appliances such as induction stovetops and heat pumps growing ubiquitous in homes, modern American society is transitioning away from fossil fuels to electric power from renewable energy sources, with the advent of climate change motivating even more rapid advancement.
But an electric — and more climate-resilient — future is far from inevitable; its implementation will depend on a complex process of societal change that will challenge lifestyles, work patterns and collective decision-making methods. Additionally, new renewable energy technologies will need power infrastructures and systems designed to support them.
Ricardo Pinto de Castro, an assistant professor of mechanical engineering at the University of California, Merced, and a principal investigator (PI) at the Center for Information Technology Research in the Interest of Society and the Banatao Institute (CITRIS), has been interested in exploring how people adopt new technologies from his earliest days as a researcher.
“In undergrad, I really enjoyed opening a book and reading it from start to end,” said de Castro. “I am always driven to learn why things work the way they do. If you are in academia, you have to be a curious person, because the ‘why’ question is very important.”
After obtaining his licenciatura, a five-year equivalent to a bachelor’s degree, in electrical and computer engineering from the University of Porto in Portugal in 2006, de Castro applied a longtime fascination with vehicles toward launching a startup, WemoveU, with the goal of developing the first iteration of motor controllers for low-velocity EVs. Alas, he was ahead of his time; a shortage of customers for the nascent technology prompted his return to the University of Porto to pursue a doctorate, again in electrical and computer engineering, which he completed in 2013.
De Castro then returned to the EV industry, working for eight years at the German Aerospace Center. He helped deliver solutions to some of the most prominent challenges for EVs, including reducing the large mass of batteries within vehicles with hybrid energy storage featuring high-power supercapacitors, a combination that increased power density and sped up energy transmission before the popularization of lithium and high-energy batteries.
Since joining the UC Merced faculty in 2021, de Castro has led a lab that combines power conversion with advanced control and optimization methods to achieve efficient, durable and reliable energy storage in electric and robotic vehicles. His team also explores the automation of vehicles, emphasizing safe motion planning and resilient control systems.
In 2022, de Castro received a University of California Hellman Fellowship Award, which recognizes outstanding early-career faculty. He has also joined the research team of the UC Merced Valley Institute for Sustainability, Technology & Agriculture (VISTA), launched in 2023 as part of an unprecedented $65 million federal grant to boost economic growth in California’s Central Valley.
A senior member of IEEE, the world’s largest technical professional organization, de Castro serves as chair of the Vehicular Technology Society and the Automated Vehicles Standards Committee and as editor for the IEEE Transactions on Vehicular Technology journal. In recent years, de Castro has also served as an expert evaluator for the National Science Foundation (NSF) in the U.S. and the Research Executive Agency of the European Union.
Helping farmers clean the air over the Central Valley
Arriving in sunny Merced with a self-proclaimed passion for vehicles and a professional mission to develop robust, climate-resilient energy systems, de Castro quickly found a new avenue of exploration just outside his office door.
“When you come to UC Merced, around the campus you see farms. When you look into the tractors that are operating on these farms, most of them still rely on diesel engines,” said de Castro. “So I realized, why not electrify the tractors as well?”
Agriculture is California’s largest source of smog-forming nitrogen oxide (NOx) emissions, due to both fertilizer use and the fleets of diesel-powered vehicles required to plow fields and harvest crops. Significant research efforts have worked to investigate the technological hurdles of transitioning off-road agricultural vehicles from internal combustion engines to electric motors.
However, the farm owners themselves are left with a plethora of questions to consider before purchasing an electric vehicle: How does the operational cost of an electric tractor compare to that of a diesel machine? For which tasks is an electric tractor best suited? What would it take to install charging infrastructure? How often does the darned thing need to be plugged in, anyway?
After all, while electric tractors eliminate NOx emissions, they have lower maximum horsepower than diesel tractors, making it difficult to address heavy-duty tasks that engage with the soil, such as tilling. The machines also must take regular breaks to recharge, a significant complication in the face of time-sensitive planting and harvesting tasks.
In 2021, de Castro received a CITRIS Seed Award that allowed him to examine the long-range picture of tractor electrification and its real-world feasibility in the agriculture industry.
“CITRIS provides resources for researchers like me to go deeper into investigating problems for the benefit of society,” said de Castro. “It’s very rewarding to be part of this community, because our values are in alignment.”
Collaboration to ease a complicated process
Working with co-investigators Reza Ehsani, a professor of mechanical engineering at UC Merced, and Stavros Vougioukas, a professor of biological and agricultural engineering at UC Davis, de Castro sought to address the farmers’ questions as comprehensively as possible.
The team’s resulting product, an interactive application referred to as the “techno-economic tool,” evaluates the total cost of owning electric and hybrid tractors to help farmers balance operating expenses, machine performance and air pollution generated by their work.
“Working with Ricardo enabled us to put our expertise together and learn from each other to develop this project. The results could help the agriculture industry significantly.”
Reza Ehsani
Using data from local farmers collected by Ehsani and Vougioukas, the team incorporated a wide range of methods to assess electric and hybrid tractor performance, including a simulation of the tractor to determine annual fuel consumption and NOx emissions, an economic model to estimate total implementation costs, and novel decision maps that indicate to farmers where deployment of electric tractors is most financially viable.
In order to better manage energy in hybrid tractors, they also developed a power split strategy based on model predictive control, an optimization technique that uses known data to predict future behavior, which allows users to balance energy efficiency and NOx emissions with the operational constraints of the electric powertrain.
De Castro and team found that, compared to diesel engines, electric tractors are already competitive for light-duty farming activities, while hybrid powertrains are more cost-effective for medium-duty tasks.
The cross-disciplinary expertise backing the project, with Vougioukas and Ehsani’s knowledge of farming operations and de Castro’s power systems background, provided the proper scope to make a tangible effect on the agriculture sector.
“Working with Ricardo enabled us to put our expertise together and learn from each other to develop this project,” said Ehsani. “The published results of our work could help the agriculture industry significantly.”
The tool provides groundbreaking insight into the feasibility of electric tractor adoption in a format accessible to growers, while accounting for the variability inherent to real-world agriculture operations. Tractor manufacturers offer another potential market for the new technology, which could help them demonstrate to potential buyers which equipment is most suitable for their unique needs.
But electrifying a farm’s fleet of tractors takes more than just swapping one type of motor for another. Diesel tractors are ubiquitous, a trusted technology that farmers have been using and maintaining for decades, often learning them inside and out with the same dedication as sports car enthusiasts.
Widespread adoption of new machinery and infrastructure will require close and careful collaboration between the technology’s developers and its users to maximize economic and environmental benefits. De Castro emphasizes the responsibility that scholars bear to make the purpose and methods of these changes transparent.
“As researchers, we need to have a continuous awareness that we should not impose this technology, but rather recognize the concerns of farmers and help them understand the benefits better,” said de Castro. “This will be an important hurdle to overcome in the next few years.”
Out of the lab and into the world
De Castro is committed to taking his innovations from the realm of theory out into the field. In 2022, with support from UC Merced’s Office of Technology, Innovation, and Industry Relations, he launched a startup called HyVerde to commercialize his battery research.
The company’s hybrid battery management system ingeniously integrates multiple battery chemistries into a single battery pack to benefit from the strengths of each chemistry, such as faster charging capability, longer lifespan and more cost-effective manufacturing based on abundant materials.
“CITRIS provides resources to go deeper into investigating problems for the benefit of society. It’s very rewarding to be part of this community, because our values are in alignment.”
Ricardo de Castro
HyVerde is developing the power conversion hardware and control software to enable the integration, and expects to bring the technology to electric transportation, including electric aircraft, and stationary energy storage.
The team’s work has received support from the California Sustainable Energy Entrepreneur Development (CalSEED) program funded by the California Energy Commission.
Not only does de Castro want to make electric vehicles more efficient and widespread; he also seeks to make them safer. In 2023, he was awarded a $1.1 million California Climate Action Seed Grant to help communities and the state government create emergency evacuation strategies with electric vehicle infrastructure in mind.
Unpredictable disasters, such as wildfires, earthquakes and floods, may disrupt the power grid and prevent EV charging, potentially compromising the safe evacuation of EV users. De Castro’s effort will provide planning, decision-aid tools and policy recommendations.
Driving an electric future
Since joining the UC Merced faculty, de Castro has taken pride in helping students find their own professional paths, equipping them with critical skills and firsthand knowledge of a research laboratory environment.
True to his love of all things motorsports, de Castro serves as an adviser for UC Merced Society of Automotive Engineers (SAE) student group, where he supports the Bobcat Racing EV team that is designing and constructing a formula-style race car to compete in the Formula SAE competitions.
“Formula SAE provides students with the opportunity to develop their engineering skills in a variety of disciplines, including design, fabrication and testing of prototype vehicles,” he said. “Students also gain experience in project management and team collaboration, which will be essential for their professional success.”
He also advises the UC Merced team competing in the three-year U.S. Department of Energy Battery Workforce Challenge, where the students are tasked with designing and integrating an EV battery pack into a Ram ProMaster vehicle.
A three-time host in the CITRIS Workforce Innovation Program, de Castro has mentored multiple undergraduates during summer internships, including UC Merced computer science and engineering student Amrita Mohandas, who helped build small, mobile ground robots to conduct forestry research during the program’s very first year.
“I think it was a very rewarding experience for the students, and it was good for me because I was able to learn more about them,” said de Castro. “The internship helps them gain professional and research skills, and it paves the way for whatever they want to do in the next stage of their career.
“They can understand, ‘Oh, I really like research. I want to go to graduate school, or I really like industry and would like to pursue this direction.’ It’s a really unique experience.”
Such an experience helped inform Mohandas’s decision to continue her studies; she is now working on a master’s degree in computer science at Texas A&M University.
The future is electric, and thanks in part to de Castro’s research and teaching efforts, it’s in good hands.
In-set photos courtesy of Ricardo de Castro