The US National Renewable Energy Laboratory (NREL) published June 12 the world’s first global best practice report for Concentrated Solar Power plants.

The report sets out recommendations to improve the performance and reliability of Concentrating Solar Power tower and trough plants, using feedback from 80% of global CSP capacity.

Many of the problems faced by solar thermal operators related to the implementation of correct designs and operations, rather than technology gaps, but certain designs could be improved, NREL said.

Plants based on more established trough technology are generally operating at high availability, NREL said.

The reliability of less mature tower systems, most of which are now incorporating modern salt storage, is currently less demonstrated, it said. The failure of the Crescent Dunes plant in Nevada, the world’s first CSP tower with molten salt storage, dented investor confidence. Tower operators participating in the study reported challenges with salt storage systems, as well as valves and receivers.

Project management and transient conditions are two key areas for improvement, a new global CSP report finds. (Image credit: NREL)

The report recommends a greater focus on the impact of transient conditions on the plant, such as intermittent solar resources and rapid ramp up or shut down requirements.

CSP plant and equipment must be designed to meet the sharp temperature changes brought about by transient conditions, particularly in higher temperature CSP tower plants, NREL said.

Performance models should take into account transient plant behaviors, to avoid overestimating output, it said. Highly detailed solar and wind resource assessments are required, it noted.

Most technology issues can be resolved by appropriate component selection by experienced CSP engineers and careful attention should be paid to heliostat quality, the report said.

Engineering procurement construction (EPC) companies must implement rigorous quality assurance throughout the installation of the plant, particularly on key systems such as heat exchangers, turbines and pumps, it said.

EPC groups must also place greater focus on control systems and automation when installing the plant, and plant owners should hire an experienced engineer to support them during all phases of the project, alongside an independent engineer.

                      CSP tower receiver issues by frequency, impact 

Source: NREL’s Concentrating Solar Power Best Practices Study, June 2020.

Plant owners should integrate experienced O&M teams early in the installation process to ensure the plant is optimized for operations, NREL said.

«Many participants recommend that the O&M company operates the plant under the supervision of the EPC during commissioning,» it said.

Project developers must ensure the selected EPC has sufficient expertise and resources to build CSP plants as some EPC groups have struggled with cost, schedule and performance under fixed-price, full wrap contracts, the report said.

«We went in thinking this would be about technology, but literally over half of the issues identified were about implementation—how to do it right, the structure of the project, the relationship of the parties, and having a clear definition of what the projects are trying to achieve,» NREL said.

«None of [the issues] are insurmountable…Based on our findings, the authors are confident that future tower and trough plants can be built on time and within budget and will perform as expected,» it said.