Passive cooling articles may include a first element defining a high absorbance in an atmospheric infrared wavelength range and a high average reflectance in a solar wavelength range. The first element may define a first major surface (114, 214, 314, 414) positioned and shaped to reflect solar energy in the solar wavelength range to an energy absorber (108, 208, 308, 408, 508, 608) spaced a distance from the first major surface (114, 214, 314, 414). The energy absorber (108, 208, 308, 408, 508, 608) may be a heating panel or a photovoltaic cell. A second element may define a high thermal conductivity and thermally coupled to a second major surface (116, 216, 416) of the first element to transfer thermal energy from the second element to the first element to cool the second element.

A dynamic controllable system 10 for moderating energy absorption at the earth's surface includes a series of panel units 110, 610 mounted above the earth's surface over land and water masses. Each panel unit 110, 610 supports rotatable shafts 112, 612, with panels 100, 600 joined to or integrally formed with the shafts 112, 612. Each panel (forcing) 100, 600 has a radiation reflective surface 102, 602 and a radiation emissive surface 104, 604 opposite the radiation reflective surface 102, 602. The panels 100, 602 are selectively rotated into a predetermined one of a plurality of cardinal positions: reflective, emissive and neutral, or into an intermediate position between two of the cardinal positions. The programmable controller 130 receives various data including top of atmosphere satellite data, air temperature and relative humidity at panel units, weather data, time of day, position of panel units, radiation insolation, and combinations thereof. Responsive to real-time data, both local and regional, the programmable controller directs rotational orientation of panels within the panel units, causing a desired reflection of shortwave and longwave radiation away from the earth's surface.

An air curtain control system for a solar thermal receiver comprising: at least one air jet (505) arranged to produce a continuous planar air curtain (507) over at least a portion of a receiver aperture 509 of a solar thermal receiver, an air flow control device (517) for controlling a speed of air flow out of the air jet (505), at least one angular control device (503) for controlling an angle of the air curtain (507) relative to the receiver aperture 509, and a system controller (501) arranged to control the air flow control device (517) and angular control device (503) to isolate the receiver aperture (509) from ambient elements external to the receiver aperture (509).

The invention relates to a method for preparing a hydrocarbon by reducing CO.sub.2, wherein CO.sub.2 is reduced to a hydrocarbon with the aid of a directly heated electrode. A device for carrying out a corresponding method, a corresponding power plant and a system comprising said power plant and a vehicle with a combustion engine are also objects of the invention. The method and device may, e.g., be used as a micro-energy system for decentralized energy supply.

A material may be included in a cooling film or cooling panel to achieve cooling even under direct solar irradiation. The material includes one or more constituent materials and an outer surface configured to interact thermally with the atmosphere and with solar radiation. The material exhibits an emissivity of at least 0.8 in spectral range of 5 μm to 15 μm, an ultraviolet reflectivity of at least 0.5 in the spectral range of 275 nm to 375 nm, an ultraviolet absorptivity of at least 0.75 in the spectral range of 275 nm to 375 nm, or a combination thereof. A cooling film, or cooling panel, may be affixed to an exterior surface of a vehicle, structure, or system to provide cooling even under direct solar irradiance.

A dynamic controllable system 10 for moderating energy absorption at the earth's surface includes a series of panel units 110, 610 mounted above the earth's surface over land and water masses. Each panel unit 110, 610 supports rotatable shafts 112, 612, with panels 100, 600 joined to or integrally formed with the shafts 112, 612. Each panel (forcing) 100, 600 has a radiation reflective surface 102, 602 and a radiation emissive surface 104, 604 opposite the radiation reflective surface 102, 602. The panels 100, 602 are selectively rotated into a predetermined one of a plurality of cardinal positions: reflective, emissive and neutral, or into an intermediate position between two of the cardinal positions. The programmable controller 130 receives various data including top of atmosphere satellite data, air temperature and relative humidity at panel units, weather data, time of day, position of panel units, radiation insolation, and combinations thereof. Responsive to real-time data, both local and regional, the programmable controller directs rotational orientation of panels within the panel units, causing a desired reflection of shortwave and longwave radiation away from the earth's surface.

A dynamic controllable system 10 for moderating energy absorption at the earth's surface includes a series of panel units 110, 610 mounted above the earth's surface over land and water masses. Each panel unit 110, 610 supports rotatable shafts 112, 612, with panels 100, 600 joined to or integrally formed with the shafts 112, 612. Each panel (forcing) 100, 600 has a radiation reflective surface 102, 602 and a radiation emissive surface 104, 604 opposite the radiation reflective surface 102, 602. The panels 100, 602 are selectively rotated into a predetermined one of a plurality of cardinal positions: reflective, emissive and neutral, or into an intermediate position between two of the cardinal positions. The programmable controller 130 receives various data including top of atmosphere satellite data, air temperature and relative humidity at panel units, weather data, time of day, position of panel units, radiation insolation, and combinations thereof. Responsive to real-time data, both local and regional, the programmable controller directs rotational orientation of panels within the panel units, causing a desired reflection of shortwave and longwave radiation away from the earth's surface.

Falling particle solar receivers, systems, and methods are disclosed that include one non-linear falling particle curtain or two or more falling particle curtains within a solar receiver that receives incident solar radiation. The particles heated in the solar receiver may be used to heat a secondary fluid. In an embodiment, the particles may be recirculated to improve energy capture and thermal efficiency. In other embodiments, an air curtain may be used across the aperture of the receiver, and flow-control devices may be used to evenly spread particles across the width of the receiver inlet. Finally, feed particles may be preheated using heat from the solar receiver.

Falling particle solar receivers, systems, and methods are disclosed that include one non-linear falling particle curtain or two or more falling particle curtains within a solar receiver that receives incident solar radiation. The particles heated in the solar receiver may be used to heat a secondary fluid. In an embodiment, the particles may be recirculated to improve energy capture and thermal efficiency. In other embodiments, an air curtain may be used across the aperture of the receiver, and flow-control devices may be used to evenly spread particles across the width of the receiver inlet. Finally, feed particles may be preheated using heat from the solar receiver.

An air conditioning system and method of air conditioning is provided. The air conditioning system includes an intake mechanism configured to draw into the air conditioner a first amount of air and an amount of moisture from an exterior of the air conditioner. The system further includes metal organic frameworks in fluid communication with the intake mechanism, the metal organic frameworks configured to adsorb the amount of moisture from the first amount of air. The system further includes an indirect evaporative cooler configured to cool the first amount of air. The system further includes a solar heater configured to heat a second amount of air. The system further includes a heat exchanger configured to contact the second amount of air with the metal organic frameworks to regenerate the metal organic frameworks.