Texas Tech University

Assistant Professor Working to Use Concentrated Solar Energy to Demonstrate Processes for Energy-Efficient Seasonal Energy Storage, Production of Green Ammonia

Amanda Bowman

March 3, 2022

Mahdi Malmali received a $2.05 million grant from the U.S. Department of Energy.

Ammonia is one of the most commonly produced industrial chemicals in the U.S. According to the American Chemical Society, about 80% of produced ammonia is used in agriculture as fertilizer, which helps feed humankind.

However, the production of ammonia emits CO2 gasses, said Mahdi Malmali, an assistant professor of chemical engineering in Texas Tech University's Edward E. Whitacre Jr. College of Engineering.

To help curb that issue, Malmali received a $2.05 million grant from the U.S. Department of Energy's Energy Efficiency and Renewable Energy Solar Energy Technologies Office (SETO) to advance concentrating solar-thermal power research and development to help eliminate CO2 emissions from the energy sector.

Malmali said the project has two objectives: to produce ammonia in a solar reactor at the time of demand for fertilizer and to produce ammonia for storage.

“The way we are producing ammonia at this point is very energy-intensive,” Malmali said. “It's one of the most efficient chemical engineering processes, but it still relies on fossil fuels, and it's contributing to almost 2% of the CO2 emissions worldwide. The production process is typically happening only in centralized locations, and the locations of the end-users – farmers – are far away.

“The topic of this proposal is how to use renewable energy to produce ammonia, and we're trying to use concentrating solar power (CSP).”

Malmali likened the process to using a magnifying glass to start a fire on a piece of paper, harnessing the heat from the sun to run chemical processes.

“The thermochemical energy storage side of this process is unique, interesting and challenging,” he said. “If you store energy in the form of ammonia, it will provide a path for dense, seasonal storage at the utility-scale, which is outside the scope of batteries. Additionally, one can move that ammonia - which is essentially a very concentrated hydrogen - around, and then you can supply that energy to various processes to refineries' cement kilns or use it as a reagent in steel mills. So, this project is focused on making the process to manufacture ammonia green by using solar energy and seasonal energy storage.”

Malmali is the principal investigator on the project and is working with the University of Minnesota, Twin Cities and the Research Triangle Institute (RTI). Instead of building an actual CSP array, Malmali and his team are going to copy it.

“Minnesota is providing separating materials as well as doing the control and modeling while RTI is helping with the technology to market and also catalyst down selection,” Malmali said. “We are going to mimic the sun by providing heat using a furnace, not really having a concentrating mirror reflecting the sun into the reactor.”

Malmali was selected as a part of the SETO Fiscal Year 2021 Photovoltaics and Concentrating Solar-Thermal Power funding program, an effort to advance solar energy research and development to find innovative solutions that will enable a decarbonized electricity system by 2035 and a 100% clean-energy economy with net-zero emissions by 2050.

“This is a great way to decarbonize the ammonia industry,” Malmali said. “The best place to use the decarbonized energy is in the chemical business because it's easy to integrate. In other processes like cement or steel, it's relatively complicated to decarbonize because their energy intensity is significantly more and they need a significantly larger renewable-based process.”

Malmali's project is one of several that will research and develop CSP technologies that help reduce costs and enable long-duration solar energy storage and carbon-free industrial processes in the U.S.

About the Solar Energy Technologies Office

The U.S. Department of Energy's Solar Energy Technologies Office supports early-stage research and development to improve the affordability, reliability and domestic benefit of solar technologies on the grid. Learn more at energy.gov/solar-office.