A pair of Colorado School of Mines-led teams have been awarded more than $2 million by the U.S. Department of Energy for research that could lower the cost of solar electricity.
Greg Jackson, professor of mechanical engineering, and Xerxes Steirer, research assistant professor of physics, are the lead investigators on the two projects, which are part of a $53 million investment by DOE’s Solar Energy Technologies Office to advance early-stage solar technologies.
Jackson and his team at Mines, in collaboration with Sandia National Laboratories and Carbo Ceramics Inc., will receive $1.86 million to develop a new method for capturing and storing thermal energy from concentrating solar power (CSP) into engineered ceramic particles. Such storage on very large scale should overcome the performance, durability and cost barriers to current energy storage systems based on molten salts.
“Concentrating solar power with thermal energy storage can time-shift solar-driven electricity to times when the sun is not shining. At the utility scale, our approach to energy storage provides lower-cost storage than batteries. Furthermore, with our advances in energy capture, the CSP plant with storage can outperform state-of-the-art photovoltaics in terms of solar efficiency,” Jackson said. “Right now, in places like California, there is so much PV that comes off the grid at night, and low-efficiency fossil-fueled power plants must pick up the slack in the evening. Efficient CSP with large-scale storage can mitigate this problem by allowing clean renewable energy to cover the high evening power demands.”
CSP works by concentrating the sun’s rays 1,000 times or more using a field of mirrors that focus on a central tower receiver. Jackson and his fellow researchers propose to capture the concentrated solar energy in narrow-channel, counterflow fluidized beds full of oxide particles that will then store the energy without corrosion and less expensively than currently used molten salts.
“Our unique fluidized bed design can transfer the heat into the particles extremely efficiently which will allow integrators to concentrate the sun at even higher levels to improve the plant efficiency and lower the receiver costs,” Jackson said.
As part of the project, researchers will test a demonstration-scale version of the system at the National Solar Thermal Test Facility at Sandia, where Mines alumnus Kevin Albrecht PhD ‘16 is a senior member of the technical staff who will be working on the project.
Also contributing to the project are Ivar Reimanis, Herman F. Coors Distinguished Professor of Ceramic Engineering at Mines; Albrecht, Andrea Ambrosini and Clifford Ho at Sandia; and Brett Wilson of Carbo Ceramics.
The other Mines project awarded DOE funding will receive $200,000, for work to enhance defect tolerance of high-efficiency mixed perovskite PV materials.
Specifically, Steirer, facilities director at the Renewable Energy Materials Research Science and Engineering Center (REMRSEC), and his team will work to validate solutions to perovskite degradation caused by water and oxygen, electrical bias, light and elevated temperature by performing in situ measurement of chemical reactions, volatile species and electronic structure. Experiments will use Mines’ new environmental X-ray photoelectron spectrometer (E-XPS), which provides real-time chemical information of interface reactions.
Collaborating on the project are Angus Rockett, professor and department head of metallurgical and materials engineering at Mines, as well as experts from the National Renewable Energy Laboratory and industry partner Hunt Energy Enterprises LLC.
Distinctly different from traditional silicon solar, perovskite solar materials can be made from solutions and cast into films on many types of surfaces and at high speed. With conversion of solar to electrical energy already near 22 percent efficiency, scaling up the technology hinges upon researchers’ ability to increases perovskite tolerance to conditions such as damp heat, Steirer said.
“With the new Rocky Mountain E-XPS surface analysis facility at Mines, we aim to accelerate validation of new materials by combining experiments and measuring the effects in real time,” Steirer said. “For example, testing materials for resilience in hot and humid conditions usually takes many weeks or months in most labs and is important for solar panels expected to run for 30 years and more. We aim to build new EXPS-based tests that have an answer on each new material much faster. This characterization advancement can enable material tolerance optimization in a way that has never been done before.”
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