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Hydrogen Mitigation and Management Method for Concentrated Solar Power (CSP) Parabolic Trough Power Plants

National Renewable Energy Laboratory

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Technology Marketing Summary

Concentrating solar power (CSP) utilizes solar energy to drive a thermal power cycle for the generation of electricity and comprises technologies (i.e., parabolic trough, linear Fresnel, power towers, and dish engine systems) that deliver low emission, flexible, and reliable power. Due to these benefits, the global CSP market is forecast to grow at a 19.4% CAGR to reach a market size of $8.7 billion in 2020, according to Transparency Market Research. Within CSP technologies, parabolic trough power plants accounted for approximately 70% of the global CSP market in 2015 and are expected to maintain their prevalence within the CSP market through 2025, according to market research firm Market Insights.

Parabolic trough power plants are a reliable CSP option and collect thermal energy in an organic heat transfer fluid (HTF). However, operating this HTF at its maximum temperature slowly degrades the mixture, which generates hydrogen gas (H2). During normal operation of parabolic trough power plants, hydrogen present within the HTF permeates across the power plant’s absorber tubes and into the receiver annuli, which contain getters designed to absorb hydrogen. When these getters saturate hydrogen buildup occurs rapidly within the annuli, which increases heat loss from the receivers and decreases their thermal efficiency. Analysis has estimated that hydrogen accumulation in 50% of the collector field receivers decreases net electricity production by about 11%. Thus, researchers at NREL have developed a novel hydrogen mitigation and management method for CSP parabolic trough power plants. 

Description

NREL researchers have developed a novel method for hydrogen management within parabolic trough power plants. This method is based on a module that removes only hydrogen from the HTF within the expansion tanks at a desired rate, maintaining hydrogen levels in the HTF circulating in the collector field. When implemented with moderate purge rates, getters within new receivers are able to operate for the full 30-year lifetime of the power plant. When implemented with aggressive purge rates, saturated getters within the collector field can be regenerated, restoring receiver performance.

More recently, NREL researchers developed an integrated module that functions to both separate hydrogen from the HTF and monitor hydrogen levels in the expansion tanks. This integrated module combines the hydrogen separation and hydrogen sensing functions into a single unit.

NREL researchers have also developed a method to assess hydrogen levels in the solar collector field of an operating parabolic trough power plant. This measurement method regularly monitors hydrogen within the circulating HTF so that the impact of the mitigation method on the collector field receivers can be measured on a weekly or daily basis.

Benefits
  • Enables exclusive removal of hydrogen from expansion tanks at controlled rates
  • Ensures performance by continuously measuring hydrogen levels within the expansion tanks
  • Enables getters of new receivers to operate for 30 year plant lifetime
  • Enables regeneration of saturated getters if aggressive purge rates are used
Applications and Industries
  • Power Plants
  • Maintaining Hydrogen Levels within Power Plants
  • Parabolic Trough Power Plants
  • Concentrated Solar Power
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
NREL ROI 16-10, 16-59, 16-111, 17-71PrototypeAvailable06/28/201706/28/2017

Contact NREL About This Technology

To: Erin Beaumont<erin.beaumont@nrel.gov>