Utilities Middle East
ADVANCEMENTS IN HELIOSTATS COULD HELP LOWER CSP COSTS
Heliostats can represent half of the capital costs of a Concentrated Solar Power plant and misalignment can severely impact performance. Alignment issues become more significant for larger projects due to the greater distances between heliostat and solar thermal tower
As Concentrating Solar Power developers drive for lower costs, heliostat performance has become a key area of research. Auto-calibrating heliostat systems that are expected on the market soon, will cut capex, accelerate construction times and expand siting potential. Heliostats can represent half of the capital costs of a Concentrated Solar Power plant and misalignment can severely impact performance. Alignment issues become more significant for larger projects due to the greater distances between heliostat and solar thermal tower.
At NRG Energy’s giant 377 MW Ivanpah tower plant in California, online since 2014, heliostat positioning problems caused by soiling and windstorms contributed to the facility missing production targets in its first 24 months of operations. In 2016, misaligned heliostats caused a fire in a section of one of the plant’s towers, reducing output by a third for over a month.
A number of technology teams are now using the latest camera and automation tools to develop selfcalibrating heliostat systems.
These solutions are set to have multiple benefits, accelerating construction times and improving plant performance, and could be deployed within a year, developers told New Energy Update.
hardware would be «less than current offerings,» Villasante said.
The system has already been demonstrated within several heliostats and the partners are looking to work with suppliers to develop a more «industrialized» and integrated solution, he said. Advanced algorithms
U.S. CSP start-up Heliogen has created a cuttingedge computing solution that pushes performance boundaries, even with low-cost heliostat systems. Backed by Bill Gates, Heliogen has developed an autonomous system that calibrates heliostats based on a «closed-loop» algorithm.
The system uses cameras and advanced computer vision software to align heliostats more accurately and increase solar efficiency. Tests have shown increased accuracy of reflected sunlight can achieve temperatures exceeding 1,000° C, the company said.
“We can achieve high pointing accuracy (submilliradian normal vector errors) with a comparatively low-cost drive system, because the closedloop controller can correct for nonlinearities and other manufacturing variability that an open-loop controller would find difficult or impossible to correct,” Fatimah Bello, VP, Business Development & Product at U.S. CSP start-up Heliogen, said.
Smart calibration technology can rapidly reduce installation times and construction costs by allowing simultaneous calibration of heliostats.
“Our system eliminates the long process of calibration for the heliostat field – it’s a matter of hours to days to get the field up and running, not months,” Bello said.
Self-calibration solutions also allow for faster, low-cost planting methods for heliostats, further reducing labor costs. The installation benefits would be greatest at sites with large civil works requirements and high labor prices.
“One of the key benefits pursued with this technology is strong focus to speed up and drive down costs during the start-up and commissioning of the solar field,” Blazquez said.
All of the developers see opportunities for retrofitting their self-calibrating heliostat technology to existing plants, although the cost-benefits would differ between the solutions and depend on sitespecific factors.
Heliogen sees immediate opportunities for new CSP projects that supply heat to industrial facilities with restricted land availability. By increasing the accuracy of the heliostats, smaller heliostat fields can be proposed at lower cost, Bello said.
“Just recently we were able to propose a heliostat field that was almost 20% smaller than the customer expected,” she said.
Heliogen is currently examining projects with payback periods of as low as two years, Bello said. “We are currently proposing projects for Q4 2020 and Q1 2021 implementation,” she said.