by Audrey Resutek | MIT Joint Program on the Science and Policy of Global Change
January 20, 2015
To understand big problems—like the challenges facing China’s electricity grid—you have to ask big questions, says Chiao-Ting Li, a postdoctoral associate who joined the China Energy and Climate Project last summer. Li, who began her research career as an automotive engineering student focusing on electric vehicles, is now studying emissions and renewable energy in China.
At the China Energy and Climate Project, Li studies large-scale issues related to China’s energy system, such as how the country can reliably add more wind power to its electricity generation mix, and the effect of policies limiting emissions in cities. But this focus on bigger picture problems is a recent development—she began her career by studying what goes on under the hoods of solar and plug-in electric cars.
“Mechanical engineers understand what’s happening in one car very well, but they don’t know about what’s happening across multiple cars,” says Li, who is the 2014–2015 Shell-MIT Energy Fellow. “I eventually became interested in bigger picture questions, like how does the electric grid handle the increased load from plug-in vehicles.”
During her graduate studies Li focused on automotive engineering, receiving a Master’s Degree in Mechanical Engineering from National Taiwan University, and a PhD in Mechanical Engineering from the University of Michigan.
She put these engineering principles into practice at National Taiwan University—where she twice participated in the World Solar Challenge, an elite 10-day race across the Australian Outback. Competing against teams from universities and automakers across the globe, the National Taiwan University team scored well, in 12th, and then 5th places in the years that Li joined.
“It was the best experience an engineering student can ask for, to build a car and have it really work,” Li says. “You’re using these principles you’ve learned about in textbooks, and it’s sort of an aha moment when it works exactly as you calculated.”
Inspired by her hands-on experience at the World Solar Challenge, Li decided to pursue a PhD studying automotive engineering at the University of Michigan. Her research there focused on powertrain design in hybrid vehicles, but she didn’t leave the race track behind. Li worked on race strategy optimization with the university’s solar car team—studying whether it pays off to hedge in tough situations, say when the weather is bad, or if it is better to risk speeding up to power through a storm.
Li’s doctoral thesis focused on problems that arise when large numbers of plug-in electric vehicles draw power from the grid. As electric vehicles become more popular, they have the potential to drastically change energy demand. If the electricity mix in a region is dominated by coal, the increase in energy generation needed to fuel the cars can actually increase emissions in the area.
Adding wind power to the electricity mix can solve this problem, Li found. In addition to being an emissions-free source of energy, wind is also available at night, which gives it an advantage over solar power for fueling electric cars. While it is available at night, wind is also intermittent, or in other words, there isn’t always steady wind to power turbines.
Electric cars offer a potential solution to this issue, as they can vary when they charge to absorb fluctuating wind generation. The uneven charging doesn’t affect driving performance, because the driving range depends on the lump sum of energy put into the battery and not how evenly the battery is charged. While theoretically feasible, this relationship would require careful coordination, she cautions.
“This is when I started to think about the energy system,” Li says. “Talking with people in different disciplines gives you a different perspective. At Michigan, an electrical engineering faculty member encouraged me to look at what was happening on the electric grid. It was like stepping into a whole new world.”
At MIT, Li studies whether or not regulations targeting emissions in cities on China’s east coast will effectively control air pollution. She and the China Energy and Climate Project group are studying a phenomenon known as interprovincial transport, wherein emitting industries relocate from an area with emissions controls to adjacent areas with less strict regulations.
“We want to know how these policies will affect overall emissions in China,” Li says. “The hiccup here is that they may not be as effective as intended. If these policies have a stringent grip on big cities, it’s going to push industry into provinces that are less developed and have less access to advanced technology. So, you potentially end up with more pollution.”
The work uses the MIT C-REM model, an economic model that can resolve the effects of policies on a provincial scale, to study how China’s air pollution policies will affect economic activity and emissions. Li collaborates with Mingwei Li, a graduate student in MIT’s Department of Earth, Atmospheric, and Planetary Sciences (who is unrelated), to model how these emissions travel through the atmosphere, and the resulting effects on regional air quality.
Li is also working on wind integration in China. Over the last five years, China has made a big push to install large wind power plants. At the same time, it is replacing smaller coal plants with larger power plants, with up to 50 gigawatts of capacity. These megaplants take more time to power up, while at the same time, China’s grid must compensate for the variability of wind power.
“On the face of things it looks like there is more variation coming in to the grid,” Li says, “but the system is actually becoming less flexible. We are studying the consequences of this, and whether there are other options or technologies that China can use to plan for its future.”
Li says that this sort of top-down policy analysis is just as important as the bottom-up technology development being done by automotive engineers. This is especially true in the energy industry, she says, where investments in generating capacity are made on a massive scale; because of this and the long lifetime of power plants, any policy put in place will affect the electricity system for years to come.
As for Li’s future, she says she may someday return to her roots in automotive engineering. “If I can work in the F1 pit someday, that’d be great. That’s actually my dream job.”