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Directory:XDOBS:Renewable Cooling and Water from Air

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Image:XDOBS renewable cooling 250.jpg

Night Radiant Condensation System

The XDOBS night radiant condensation system is a water-from-air extraction system and air conditioner that does not use any external electricity or fuel. Power is provided by an integrated solar panel. The system uses almost no moving parts, consuming 95% less energy than conventional AC systems, and is powered by an integrated solar panel.

It produces water by chilling the local air below dew point temperature. The incoming air is filtered through a HEPA-type filter to remove dust and bacteria so that the water is potable.

In arid climates, the best use of the system is for air conditioning. The system uses Night Radiant energy to send heat into the night sky. Overall, the system reduces HVAC electricity consumption by 80%, and as much as 90% during peak demand hours.

In third-world, humid climates, the best use of the system is for potable water harvesting.

Radian Cooling has been used by NASA to cool space craft, and has been tested in the Pacific Islands and Egypt. It is wsed to cool large telescopes world wide, as well as to chill large-scale cryogenics.


Official Website

Renewable Cooling presentation (pdf, 634 kb) posted here with permission

Air-to-Water presentation (pdf, 176 kb) posted here with permission

Latest Developments


Download (13 Mb mp3) - On June 23, 2007 Congress:Founder:Sterling D. Allan conducted a live, 1-hour interview with Joe Ellsworth of XDOBS as part of the weekly Free Energy Now radio series.

System Components

The system produces water by chilling the local air below dew point temperature. The incoming air is filtered through a HEPA-type filter to remove dust and bacteria so that the water is potable.

Image:XDOBS renewable cooling 600.jpg

The following elaboration of components is compiled from the two pdf documents prepared by the company.

Night Radiant panels

Shed heat to night sky or day sky when shaded 100 to 400 watts per sq meter. Chills thermal storage fluid, reaching 10F to 20F below nighttime ambient.

Designed to minimize convection and conduction and maximize radiation heat transfer

Designed to last over 20 years in outside atmospheric conditions

Dissipates between 100-140 watts of heat /square meter panel

33 square foot per gallon per night

8.8 square foot per liter per night

Produces 4950 liters per acre per night

Thermal / Wind Shield

Prevents convective warming of panel surface which allows extra chilling. Creates cold, horizontal stagnant insulating area which increases efficiency and minimizes thermal gain from surface dew.

Helps reduce the temperature by 3F

Should be installed in area where wind speed is greater than 3 MPH. Effective to 8 MPH.

Optional Wind boost

Directs wind away from panels while using wind energy to provide 4 - 7F of additional


Increase production by 50% with 7 hours per night of 8 MPH wind.

Allow system to be used in warmer and drier climates

Primary Heat Exchanger / Condenser

Transfers cold from the thermal storage fluid to indoor air. Several different types exist, but the cheapest is basically a set of 280,000 BTU radiators.

Chills air during high absolute humidity time of the day

Provides condensing surface for the water

Precisely controlled to maximize condensation

Exit air can be used as conditioned air for cooling

Effective when thermal storage fluid is at least 2F below current dew point.

Note: systems without thermal storage must do condensing during the night.

Thermal Storage Tank

A tank of fluid which contains the chilled fluid until needed for cooling purposes. It is normally insulated and buried to retain cold. Average is 3,000 gallons per 1,000 square foot per day of storage.

Optional use for improved performance

Stores cold at night to use during best humidity conditions

Sized as 120 to 300 gallons per gallon of condensate per day

Average system requires 60 to 120 days of production to replace water invested

Salt water can be used

Tank is usually provided locally

Existing cisterns can be used for thermal storage with addition of insulation

Micro Controller, Pumps, Valves, Blower, Solar charger, Battery

These components control the circulation of fluid to maximize chilling to panels and circulation of fluid to heat exchangers to maintain desired room temperatures.

Controls thermal conditions for optimal broader range of operation

Thermosyphon is used whenever possible to eliminate or reduce pumping power

Thermal drop concept is used for air flow to eliminate fan energy

Heat pipe can be used to eliminate pump energy

Optional Geoexchange heat pump can supplement water production during marginal conditions.

Optional Thermal Chimney

This is a different kind of heat exchanger. It looks like a chimney and uses diffusion type cold air release at the floor. It runs completely silent and uses convention to drive air flow, eliminating the need for most HVAC ducts. It is ideal for retrofit installs.


Provides ROI over 10 times better than photovoltaic solar panels at 2007 prices.

Can delay or remove need for major grid upgrades especially in areas with peak demand failures.

Eliminate need for rolling blackouts caused by excess power demands in the summer. (Air conditioning electricity demand is the leading cause of summer blackouts.)

Reduce standby generating requirements by up to 50%.

Dramatically reduce indirect greenhouse emissions for equipped buildings.

Incidental benefits:

Dramatically reduces roof wear due to solar exposure.

Dramatically reduces heat gain through roof.

Dramatically reduces attic temperatures.


Off grid guard shacks.

Locations with expensive power such as Diesel or propane generators.

Areas with high peak demand power costs.

Locations with High human cost if cooling is lost during power outages such as nursing homes and hospitals.

Buildings that must stay operational during power outages such as police and fire stations.

Businesses in areas where peak demand is causing high risk of grid failure.

Areas where large scale grid upgrades are needed to meet increasing demands.


Portions patent pending.

Cost for USA tests

1,000 square foot would cost $14,000 which is less than 1/10th of what it would cost to provide

refrigerated air conditioning using photo voltaic solar panels.

$14 per square foot installed.

Includes panels, thermal storage, internal air exchange, installation.

Considering test sites from 350 to 3500 square foot.

Thermal storage tanks require excavation. Can be insulated and left above ground but requires additional cost housing.

Budget 7% per year for maintenance. 1 year maintenance included.

Designed for 15 year life but should last longer.

Easy to maintain and moving components such as pumps can be replaced with standard modules.


Company: XDOBS LLC

XDOBS, an energy, water, and greenhouse emissions research compay, was founded in 2003 by Joseph Ellsworth, a Silicon Valley entrepreneur with strong embedded systems and

software optimization background. The company has been privately funded by its founders.

The company does not plan to manufacture and market the technology but is entertaining licensing agreements.

XDOBS is seeking test partners who have invested renewable solutions in the past, and who manage buildings that are off grid or who have expensive peak demand power and need cooling, who may have larger needs pending successful test outcome, and who would help publicize the results of the tests.

Other XDOBS products/technologies include:

Wind powered Freezer

Wave powered Desalination

Inventor: Joseph Ellsworth

- CTO 25 years in software and embedded systems.

– HP trained manager.

– Lead VC funded startup in silicon valley.

– Long term renewable energy research.

– Managed up to 80 people.


list here



Heber City, UT USA

phone: 800-658-8745

E-Mail: []


See Talk:Directory:XDOBS:Renewable Cooling and Water from Air

See also

Directory:Home Generation:Air Conditioning

Directory:Water from Air


- Directory







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