William Naggaga Lubega is a third-year Ph.D. student in the Department of Civil Engineering’s Energy-Water-Environment Sustainability (EWES) program at Illinois, and is one of several student members of the Critical Infrastructure and Transportation project funded by iSEE. Together with these partners, he’s asking the question: What would it take to switch the majority of Illinois transportation to electrical power, given the limitations of the state’s (and nation’s) existing power infrastructure?
More electric vehicles means more demand for electricity, and that added load can have repercussions. Lubega works at the intersection of water, ecological, and energy concerns, studying how electricity production impacts natural waterways.
Water is a critical input to electric power generation in coal, natural gas, and nuclear power plants. The water of concern is not the steam that turns the turbines in these power plants, but is the water that is used for cooling. Thermal power plants currently withdraw more water than any other sector in the United States for cooling purposes.
Where does all this water come from? Usually rivers and cooling lakes, Lubega said. And that can create all kinds of environmental problems.
When water is drawn into a power plant, it goes in at one temperature, but it leaves the plant a lot warmer because it just took energy as heat from the power generation process. The extra heat the water carries when it rejoins its source is a form of “thermal pollution,” and it’s a big concern for ecosystem health.
“Even small increases in ambient temperature — 5-10 degrees Celsius — can have significant impacts on the health of aquatic organisms like fish,” Lubega said. “When you have a drought and a heat wave (at the same time), the temperature of the water is already higher than usual, and the fish are experiencing thermal stress. You end up having to reduce the output of some of your power plants because you are trying to minimize the impact on the fish.
“What I am working on is given a certain severity of drought, how do you make decisions that ensure electricity reliability while minimizing impact on the aquatic ecosystems around thermal power plants?”
Using data from the U.S. Environmental Protection Agency, the U.S. Geological Survey, and the U.S. Energy Information Administration, he builds models that connect the known inputs and outputs of power plants with measured conditions in rivers and lakes to create a picture of environmental impact at various power plant operation levels and climate conditions. By using past data, he can build models to predict future situations.
He hopes that plant operators may someday consult his models to make decisions that balance environmental health and electricity grid reliability.
“We generally have more than enough power plants to meet demand even if we were to reduce output of some of the larger ones to minimize impact on aquatic ecosystems under drought and heat wave conditions,” he said. “But because there are constraints in the (electricity) transmission network, if you reduce output from some generators you create a situation where you make your network less reliable.”
Reliability is a measure of having enough energy to meet all users’ needs, even if a source is eliminated because of emergency or bad weather.
“The real conflict you have is not so much between do we have enough energy and are we not killing all the fish, but do we have enough power system RELIABILITY and are we not killing all the fish?” he said.
Lubega thrives in his role on the project as a translator between disciplines. He’s uniquely qualified to do it as his three degree disciplines are in different fields. He started in his home country of Uganda with a Bachelor’s Degree in Electrical Engineering from Makerere University, and moved on to a Masters of Engineering Systems and Management at Masdar Institute of Science and Technology in Abu Dhabi, United Arab Emirates. Now, he’s at Illinois earning a Doctorate in Civil Engineering.
“My personal research goal is to act as a bridge between different traditional research fields,” he said. “What interests me the most is this process of learning about a field I know nothing about to start out with — learning through classes, reading books and journal papers — and figuring out how to get them to interface more effectively in order to address a larger concern that requires knowledge from different fields.”
He’s also brimming with can-do attitude.
“The (Ugandan) education system that trains you to do a lot of work. So, I would say I definitely benefited from that because I have no difficulty being here on a Saturday afternoon slaving away,” he said. “And one thing graduate school definitely taught me … is that you can take a problem you know nothing about, study it, figure it out, and make a meaningful contribution to the problem space.
“I feel very much empowered to be a problem solver. Whenever I’m confronted with any kind of intellectual problem I’m like, ‘Yeah, I’ve got this.’ I just need to find an approach to learning all the things I need to learn.”