Goal: Create ‘Solar Fuels’ as Alternative Energy Source

Students work with the solar simulator in the lab
Doctoral students Saroj Bhatta, right, and Dassou Nagassou perform an experiment using a high-flux solar simulator to synthesize solar fuels from carbon dioxide.

By Edwin L. Aguirre

Mechanical engineering Asst. Prof. Juan Pablo Trelles loves the sun. The sun’s energy, that is. Trelles and his team are focusing their research mainly on synthesizing sustainable fuels using solar energy and carbon dioxide (CO2) — the primary greenhouse gas — as well as water or methane from natural gas.

“Solar fuels hold the promise to provide an alternative to fossil fuels, while mitigating greenhouse-gas emissions,” says Trelles, who directs the department’s Re-Engineered Energy Laboratory. The lab’s research team includes mechanical engineering doctoral students Saroj Bhatta, S. Mahnaz ModirKhazeni, Vyasaraj Bhigamudre and Dassou Nagassou from the Energy Engineering Graduate Program, as well as undergraduate students Shyam Sheth and Kayla Greeley.

“We use concentrated solar energy to directly decompose CO2 at high rates. Together with water or methane, it can form artificial hydrocarbons as fuel,” explains Trelles. “Alternatively, we can use solar energy to break down water or methane to create hydrogen gas as clean fuel. Developing the technology to produce solar fuels efficiently and cost-effectively has become the goal of several research groups worldwide, including our lab. One advantage of our process is that it could treat CO2 directly as emitted from power plant exhaust, which makes it potentially more economically viable than other approaches.” 

Close-up of the solar simulator
A close-up view of the solar simulator’s photo-thermochemical reactor.
The team is also investigating the direct use of electricity in the form of plasma — ionized gas that conducts electricity, as found inside fluorescent or neon lamps, in lightning or in the sun’s corona — for producing sustainable fuels.

“By using electricity from renewable energy sources such as solar, wind, wave and geothermal to create the plasma, we can lessen the problems associated with interruptions in incoming sunlight due to Earth’s day/night cycles and the weather,” notes Trelles. “This means we can run the process continuously 24 hours a day, reducing complexity and operating costs, and hence, increasing economic feasibility.”

Trelles was recently awarded a three-year, $150,000 grant by the National Science Foundation for the comprehensive computational modeling and simulation of turbulent plasma flows. He and his team are collaborating with researchers from the Academy of Sciences of the Czech Republic. The group has also started exploring the use of concentrated solar energy and electrical plasmas for converting organic materials (biomass) and industrial or household waste into fuels.

“We are also looking into sustainable chemical synthesis beyond fuels in order to generate high-value products, such as complex molecules and carbon-based nano products, out of low-value feedstock, or raw materials,” says Trelles.