The Energy Matrix
A Science Ebook e-zine
Spring 200
List of all editions

District Cooling

The energy matrix examines the full spectrum of future energy sources and associated problems.  It is meant to be a thought provoking publication for students who will be our future technocrats, engineers, and physicists.  We will include concepts such as solar, DG, CHP and concepts that are not practical today such as ice engines.  Send Comments to


Go to Summer 2007 Edition

Green Stimulus Package

President Barack Obama has said that he wants to fund projects that promote green or alternative energy starting day one of his administration. New Green Energy projects like transmission lines for Wind or Solar power will take years to plan and litigate.  No one wants power transmission lines in their back yard even if the back yard is the desert.  

This article is not about the controversies surrounding alternative energy.  However, recognizing that the bickering will continue makes it clear that only old technology that is already in use, can provide employment for those who are out of work.  Yet, I never hear of these projects in the mass media or in political debates. Yet their are many old proven technologies that save energy and can reduce energy consumption or produce more energy. 

The best projects to fund on day one are the ones that were started yesterday.    

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Corn Solar Collectors

The United States is looking at ethanol from corn as a renewable source of energy. The ethanol gets its energy from corn and the corn gets its energy from the sun.
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Ice from Coal ( Alchemy?)

No, this article is about thermodynamics not alchemy.  Most people get their ice cubes from coal and water.  That is they get the electric power that turns water to ice from coal powered electric power plants.

At this point, I hope you anxious to know how many pounds ice can be made from a pound of coal, because I am going to tell you. 
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Storing Carbon Dioxide
Though the effects of green house gases are debatable ( if you disagree you make my point), one effect is certain the cost of generating electricity from fossil fuels is going up. This is not debatable because utilities have already spent money storing fossil gases and continue ...
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There are two "T" in Carnot
Thigh and Tlow
End Joke
Not Funny? Try to forget it.


Heat Storage and Carbon Dioxide.

Though much about carbon dioxide storage has yet to be determined, three things are certain, that is that these stores will be huge, dense, and have temperature. The quantity of carbon dioxide that will be stored will necessitate high compression, huge volumes, and useful temperature.  The reason I say that the temperature will be useful is that there is such a large range of temperature that could be useful. A store of dense gas at twenty degrees Centigrade above room temperature would be used by a CO2/Air radiator for room heating. Stored CO2 at twenty degrees centigrade below room temperature might work well for direct cooling  (blowing air over  tubes with circulating dense cold CO2). Circulation of dense CO2  at or near room temperature would be great source of heat for the evaporator of a heat pump in heating mode.  CO2 at the same temperature would a great source of cooling of a heat pump condenser when the heat pump was operating in cooling mode..

Above ground insulated tanks of CO2 could be used for peak heat of day heat storage for heating, or they could be used to store the cool of the night as a heat sink for cooling systems during the peak usage hours of the day.


Index for all Editions


Combined Heat & Power (CHP) 

DC Power Grid

District Cooling

Ethanol Viability

Hybrid Cars

Ice made with Coal

Ice Energy Density versus Battery

Heat Storage


Nuclear Energy

Solar Heat Storage in CO2

Solar Heat Storage in Water

Storing Carbon Dioxide

Stoves - Corn Burning

Stoves - Wood Pellet Burning

Stoves - Coal Burning

Tar Sand Oil


Yucca Mountain

Substituting Coal for Diesel

Compact Fluorescent Lights








District Cooling in the city of Amsterdam

 to the lake from condenser of cooling system at 16 degrees centigrade.  The system also uses absorption type heat pumps that are driven with waste heat from industrial sites.

The Pacific ocean is also quite cool and could support district cooling in many cities close to the sea.

Puget Sound WA. USA
Water Temperature 10 degrees Centigrade


Reference 1   Reference 2   Reference 3

Other Reading Links

Heat Storage in saline pond



Why not  simply use free cooling. 

Consider a closed loop system consisting of a  sea water to water heat exchanger in the sea connected via pipes to the water to air heat exchangers in the buildings.  Tidal currents would move the sea through the heat exchangers; therefore, no power need be expended to propel the sea water through the heat exchanger. Water to Water heat exchangers are very efficient, so I will estimate the temperature differential between chilled water to sea water at only 4 degrees centigrade.  The water to air heat exchangers in the building will not be as efficient as water to water heat exchangers and will require lots power to blow air through heat exchanger radiator to sustain a differential temperature of 6 degrees centigrade.  This will require a large radiator.  The radiator in most cars using pressurized glycol mixtures designed operate with 50 degree centigrade  temperature differentials.  Lots of energy is required to circulate cooling water.

The temperature differential between the sea water and the desired temperature of the office building is only about 20 degrees centigrade. 

20 degrees - 10 degrees( heat exchanger differential ) = 10 degrees

This means that the useful heat content of the water is 18 Btu per pound.
[ Sorry about switching to English units]

1 kWH = 3414 Btu

1kWh  = 12,000 Btu of cooling 
12000 Btu of cooling per kWh is produced by a typical room air conditioner.

12000/18 = 667 pounds of chilled water.
667 pounds of water circulated to HVAC* system save 1kWh

 *HVAC = High volume Air Conditioner

Having to circulate 667 pounds of water to provide only one kilowatt of green energy would require very large insulated pipes, huge pumps, and large heat exchangers.  Making the system not economically feasible.

Dollar Value of Free Cooling

From above 667 pounds of water pumped to a building in a district cooling system provide the equivalent of 1 kWh of electricity.  One kWh from coal cost about 10 cents.  However, during periods of shortage utilities have paid as much as a dollar per kWh on the free USA free market.  Some people may have gone to prison for that though.


Combination Free Cooling and Waste Heat systems

Absorption type heat pumps can be driven by industrial or power plant inexpensive waste heat.  If you cool the condenser with free cooling to about 10 centigrade you should be able drive the evaporator to below -20 centigrade. I base this on the observations of a seven year old (me) in 1950. My family had a evaporative type or gas refrigerator. 

Thus this system could output chilled water (water/glycol mixture) at - 20 centigrade.  The temperature differential between the water/glycol and the desired temperature of the office building is now about 50 degrees centigrade versus 20 degree centigrade of the free cooling system described above.  This results in smaller pipe, heat exchanger, and water pump requirements.  Making a district cooing system practical.  


























District Cooling in Europe

The city of Amsterdam has an operating district cooling system.  Heat is dumped into a man made lake at depth of 30 meters.  Water is taken into heat exchanger at 6 degrees centigrade and returned...   

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U.S Congress to Investigate High Cost of Gasoline. ( 5-22-07)

They may not have to search very far.  In Brazil the majority of cars run on Flex fuel or pure ethanol.  In the United States less than a thousand gas stations sell flex fuel.  They are mostly in the Midwest where ethanol is produced from corn.  Brazil wants to export ethanol to us by ship.  They could supply ethanol to east coast and Gulf ports.  However, congress has placed a 54 cent per gallon  tariff on ethanol imports.

If populist congressmen really want to lambaste the oil companies, they should lambaste the oil companies for not placing  more flex fuel pumps in east coast gas stations.  Oh, but tariffs are cutting off the supply of ethanol to the east coast, so the pumps would not have much to pump.





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