📦 Resource
guide
EPA SNAP Substitutes List for Geothermal ORC – Updated Quarterly Compliance Guide
The EPA SNAP Substitutes List for Geothermal ORC is a regulatory compliance resource that identifies ozone-depleting and high-global-warming-potential (high-GWP) working fluids prohibited or approved for use in geothermal Organic Rankine Cycle (ORC) power systems under the U.S. Environmental Protection Agency’s Significant New Alternatives Policy (SNAP) Program. Updated quarterly, it serves as an authoritative reference for plant designers, operators, and regulators to ensure refrigerant and heat transfer fluid selections meet current environmental and safety standards. The guide integrates technical performance criteria with federal regulatory requirements to support sustainable, compliant binary-cycle geothermal energy generation.
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📖 Overview
Geothermal power plants using Organic Rankine Cycle (ORC) technology rely on organic working fluids—such as hydrocarbons, siloxanes, and fluorinated compounds—to convert low-to-medium temperature geothermal heat into electricity. The EPA’s SNAP Program evaluates substitutes for ozone-depleting substances (ODS) and high-GWP compounds under Section 612 of the Clean Air Act, issuing determinations on acceptability based on environmental impact (ODP, GWP), toxicity, flammability, and energy efficiency. For geothermal ORC applications, SNAP specifically assesses fluids used in closed-loop binary systems—not direct steam cycles—focusing on their lifecycle climate impact, atmospheric lifetime, and compatibility with existing turbine and heat exchanger materials. Quarterly updates reflect new scientific data, industry petitions, and evolving regulatory interpretations, including conditional acceptability (e.g., 'acceptable subject to use conditions') and restrictions (e.g., maximum charge limits, mandatory leak detection). Compliance requires cross-referencing SNAP listings with state-level regulations (e.g., California’s CARB rules) and international frameworks like the Kigali Amendment, making the guide both a technical reference and a legal compliance tool for engineering procurement, permitting, and operational audits.
📑 Key Components
1
SNAP Acceptability Status (e.g., acceptable, unacceptable, conditional)
2
Working Fluid Technical Specifications (GWP, ODP, flammability class, thermal stability)
3
Regulatory Use Conditions (charge limits, monitoring requirements, disposal protocols)