ORNL research paving way for EV changeover

By KATE COIL

As four major auto companies focus on manufacturing electric vehicles across the state, Tennessee is also producing significant research and development on how the changeover to EVs will change American infrastructure, impact the power grid, and change the trucking and logistics industries. 

Oak Ridge National Laboratories (ORNL) has long been on the forefront of many life-changing scientific developments, and its researchers continue to play a major role in helping define how EVs and related infrastructure are changing not just the country but the world.

Burak Ozpineci, section head of ORNL’s vehicle and mobility systems research section, serves both as a joint faculty member of the University of Tennessee’s Bredesen Center and as one of the researchers addressing the questions and challenges posed by the increase in electric vehicles on the marketplace. 

One of the most recent research projects undertaken by the staff at ORNL centers around how to charge electric semi-trucks to further encourage the transition from diesel to electric power in the long-haul trucking and logistics industries. ORNL researches designed architecture, software and control strategies for a futuristic EV truck stop that can draw megawatts of power and reduce carbon emissions through the use of solar arrays and batteries.

Ozpineci said charging a semi-truck requires both a different connector and more power than a basic vehicle, like a sedan or electric pickup. Where an electric car or pickup may utilize a charger that produces anywhere from 7 to 350 kilowatts, the chargers needed to power a long-distance-traveling semi-truck require around 1 megawatt of power. 

“As the power level goes up, it is harder to get that power,” Ozpineci said. “You have to find where you can get that power to see where you can install these charging stations. Most truck stops don’t have this power, so new power would have to be brought into these stops. Trucks usually drive around 500 miles a day. When they come to a truck stop, they want to stay overnight, or they have a partner so they can continue to drive. A megawatt charger would still take several hours to charge the truck. Drivers could stay overnight, but you wouldn’t have two drivers and continue to drive like when you gas up and go. That could be a challenge.”

While the charging time would work for single drivers, Ozpineci said ORNL is also looking at how trucker teams could still use multiple drivers to meet deadlines. One suggestion is switching out batteries in the vehicle at truck stops to have a continued charge. 

Another project ORNL has looked into is roadways that charge vehicles continuously through wireless charging with roads operating similarly to the wireless charging pads many use on their smart phones and other devices. 

“We started working on this in 2008, and status-wise, we have demonstrated 120-kilowatt charging through a six-inch gap,” he said. “We are sending power through air for this. You have a transmitter coil in the ground and a receiver coil in the vehicle, then you send the power through the ground. Now, we have projects that offer up to 300-kilowatt charging. We are sending 30 houses worth of power through six inches of air, nothing but air. I’ve been working on this for a long time, but to see it is still like magic.”

The challenge is making dynamic wireless charging that suites the needs of all vehicles.

“Say you wanted to drive from Nashville to Florida, you wouldn’t have to stop because we give you enough energy. We aren’t trying to charge your battery from zero to 100; we are just trying to give you enough energy that your battery charge stays the same. We have talked about that for passenger vehicles. We can do something similar for big trucks, but you need something that works for passenger vehicles and trucks because trucks need more power.”

Ozpineci said researchers are discussing ways to meet this challenge by using smaller batteries on big trucks as well as extending the range for these trucks. Dynamic wireless charging also has the advantage of helping with the power grid needs and eliminating range anxiety. 

“We have to make sure there is more generation; that is for sure,” he said. “We also have to make sure we utilize our energy efficiently. For example, we have a project right now called Smart Charge Management. You don’t have to charge your vehicle every day. With wireless charging, you don’t have to plug your car in. You bring it into your garage at low power, and it is always connected to the grid. It detects the time where charging isn’t going to be a problem for a grid and charges it then."

Battery life for EVs and what happens to those batteries after they start to lose their charge is another issue being researched. Studies have shown that continually charging batteries from empty to full actually drains the life of the battery. 

“Any time you are cycling the battery, you are using some of the life,” he said. “With EVs, there will be a lot more batteries available. I am hoping in the near future the prices will come down on these batteries, and we can use them in our houses. These back-up batteries are the same as you see in vehicles. Secondary batteries could also be used. If we have millions of EVs going around, after eight to 10 years their mile range goes down. Drivers may want to get a new battery for the EV, but the old batteries still have use. They could be adapted for use in the home. Recycling is going to be important for everything.”

Other research around EVs taking place at ORNL include reducing the size of electric drive components while maintain the same level of power, increasing wireless charging speeds and efficiency, and improving drive components for semi-trucks. 

While much of this research is being done in Tennessee, Ozpineci said he would like to see more of it being applied in the state through partnerships with the government and other entities. 

“When the governor visited here, I told him the same thing,” he said. “We are developing these technologies here, but we are going to Detroit to implement them. Why not implement them here and demonstrate them together. We could have world firsts on actual roads in Tennessee. I think would also give the people of Tennessee some pride, and help convince them to look at EVs. EVs aren’t scary; they’re actually a lot of fun.”