{
    "title": "Radiative Cooling Generator",
    "inventor_name": "Aaswath Raman",
    "publication_year": 2019,
    "device_name": "Radiative Cooling Generator (puck-in-a-dish thermoelectric device)",
    "goal": "Harvest electrical power at night by using radiative cooling to create a temperature differential across a thermoelectric generator.",
    "problem_addressed": "Lack of electricity during nighttime in off-grid or developing regions where solar panels cannot operate.",
    "concept_summary": "A passive device that radiates heat to the cold night sky, cooling one side of a thermoelectric module while the opposite side stays warm from ambient air. The resulting temperature gradient drives a thermoelectric generator that produces electricity, sufficient to power a low-power LED.",
    "detailed_description": "The prototype consists of a polystyrene disk coated with black paint, mounted on aluminum legs inside a wind shield. A commercial thermoelectric generator (TEG) is attached to the disk; its cold side faces the sky and radiates infrared heat to space, while the hot side contacts ambient air. The temperature difference (a few degrees Celsius) generates a voltage that, after conversion, powers a white LED. The system produced 25 mW m^-^2 under clear-sky conditions, demonstrating the feasibility of night-time power generation without batteries or solar input.",
    "category": "Thermal Systems",
    "principles": [
        "Radiative cooling (negative illumination)",
        "Thermoelectric effect",
        "Temperature gradient driven electricity generation"
    ],
    "scientific_domains": [
        "Physics",
        "Electrical Engineering",
        "Thermodynamics",
        "Materials Science"
    ],
    "mechanisms_of_action": [
        "Infrared radiation to cold outer space lowers temperature of sky-facing surface",
        "Ambient air heats opposite side of thermoelectric module",
        "Seebeck effect converts temperature difference into electric current"
    ],
    "materials": [
        "Polystyrene",
        "Black paint",
        "Aluminum",
        "Thermoelectric generator (e.g., Bi_2Te_3 based)",
        "Wind shield (plastic/metal)"
    ],
    "energy_sources": [
        "Ambient heat (air temperature)",
        "Radiative heat loss to night sky (cold space)"
    ],
    "inputs": [
        "Night-time clear sky",
        "Ambient air temperature",
        "Temperature differential across TEG"
    ],
    "outputs": [
        "Electrical power (~=25 mW m^-^2)",
        "Light from LED"
    ],
    "claimed_performance": "25 mW per square meter of device area; sufficient to drive a white LED; pathways suggested to reach >0.5 W m^-^2 with existing components.",
    "experimental_evidence": "Prototype demonstrated 25 mW m^-^2 night-time power generation and directly powered a white LED; results published in the peer-reviewed journal Joule (2019).",
    "replication_status": null,
    "keywords": [
        "radiative cooling",
        "thermoelectric generator",
        "night-time power",
        "off-grid lighting",
        "low-power energy harvesting"
    ],
    "related_technologies": [
        "Thermoelectric generators",
        "Passive radiative cooling materials",
        "Infrared photodiodes (negative illumination)",
        "Solar panels (as complementary source)"
    ],
    "controversy_level": "low",
    "confidence_score": 0.9,
    "practicability_score": 0.6,
    "fringe_score": 0.2,
    "evidence_strength": 0.6,
    "risk_score": 0.1,
    "trl_estimate": 5,
    "source_urls": [
        "https://www.nytimes.com/2019/09/12/science/solar-energy-power-electricity.html",
        "https://www.cell.com/joule/fulltext/S2542-4351(19)30412-X",
        "https://doi.org/10.1016/j.joule.2019.08.009"
    ],
    "organizations": [
        "University of California, Los Angeles (UCLA)",
        "Massachusetts Institute of Technology (MIT)",
        "Stanford University",
        "National Renewable Energy Laboratory (NREL)"
    ],
    "applications": [
        "Off-grid nighttime lighting",
        "Low-power remote sensors",
        "Rural electrification in developing regions"
    ],
    "limitations": [
        "Very low power density (~=25 mW m^-^2)",
        "Requires clear night sky for optimal radiative cooling",
        "Small temperature differential limits efficiency",
        "Scalability to useful power levels not yet demonstrated"
    ],
    "open_questions": [
        "How can the temperature gradient be increased without raising cost?",
        "What materials or structures can improve radiative cooling efficiency?",
        "Can the system be integrated with existing solar installations for 24-hour power?",
        "Long-term durability of the coating and thermoelectric module in harsh environments"
    ],
    "red_flags": [],
    "evidence_quotes": [
        "When paired with a voltage converter, the prototype produced 25 milliwatts of power per square meter.",
        "The device employs radiative cooling, the phenomenon that makes buildings and parks feel cooler than the surrounding air after sunset.",
        "A similar device powers NASA's Curiosity rover on Mars; its thermoelectric generator derives heat from plutonium radiation.",
        "The prototype built by Dr. Raman resembles a hockey puck set inside a chafing dish. The puck is a polystyrene disk coated in black paint and covered with a wind shield.",
        "The approach is immediately practical for lighting and off-grid sensors."
    ]
}