Available Frequency-responsive demand response refers to on-line generation that can measure frequency locally and change their power consumption after a non-zero frequency deviation is observed, in order to achieve power balance between supply and demand. For example fans and pumps that are directly driven by synchronous or induction motors, will, therefore, inherently reduce demand during frequency declines (and increase when frequency increases). Source: PNNL https://www.pnnl.gov/main/publications/external/technical_reports/PNNL-23764.pdf