Researchers have created a device to produce electricity and steam at the same time. The system is said to offer 85.1% efficiency and deliver steam at up to 248 degrees Celsius. The converter combines III–V, triple-junction solar cells and a high-efficiency solar thermal system based on parabolic trough collectors.
Scientists from the private research Tulane University in New Orleans have developed a hybrid solar energy converter which can produce electricity and high-temperature heat in one device.
The low-cost, high efficiency system is said to have a small, modular footprint, making it ideal for commercial and industrial applications in food processing, chemical production, water treatment or enhanced oil recovery.
Defined as a transmissive concentrator photovoltaic/thermal (tCPV/T) system, the converter combines a solar power generator featuring high-efficiency III–V, triple-junction solar cells and a solar thermal system based on parabolic trough collectors.
The scientists applied a water-cooled, spectral-splitting tCPV module with a conversion efficiency of 39.9% to a dimple plate cavity thermal receiver with independent temperature control of the two components and separate harvesting of ultraviolet (UV) visible and infrared light.
One of the challenges was keeping the temperature of the PV cells below 110 degrees Celsius, said the researchers, who used a microfluidic cooling system on the panel.
“Our tCPV cells serve as both electricity generators and spectrum splitters, with minimal incident angle sensitivity and no major additional components other than the requisite CPV cooling system,” the researchers said.
The system generates electricity from solar cells which were designed in partnership with U.S. manufacturer Boeing-Spectrolab – which works with solar for space exploration – and redirects infrared rays of sunlight to the thermal receiver which has an highly-absorbent coating. The rays are thus converted to thermal energy.
“We fabricate and test multiple tCPV/thermal receivers … ramping the collector area from 0.25 to 2.72m2 to increase the system power and effective concentration factor,” said the researchers, whose work is outlined in the paper Solar Cogeneration of Electricity with High-Temperature Process Heat, published in Cell Reports Physical Science and on the ScienceDirect website.
The device was tested using a solar simulator and a natural AM1.5G spectrum in San Diego, California. The results indicated system energy efficiency of 85.1%, 138 W of electric power at 304 suns, 903 W of hot water output, and 1,139 W of high-temperature steam output. The projected levelized cost of energy (LCOE) generated was estimated at $0.03/kWh.
“System economics based on a 2.72m2 prototype performance is shown to be at or near market competitiveness to natural-gas-produced process heat for a variety of locations,” said the group.
The technical and economic feasibility of the device would depend, according to the researchers, on abundant solar resources, proximity to an end user and availability of space for collectors and storage.
Source: pv magazine