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

Corn Solar Collectors

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.    

 continue reading  center column






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.
 continue reading  center column


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. 
continue reading  center column


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 ...
continue reading  center column


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








Corn Solar Collectors (continued)
Ethanol From Corn

Duty Cycle:

Solar panels convert over 10% of incident solar energy to electricity.  They are not very effective on cloudy days.  Photosynthesis works quite well using only cloud scattered and filtered light.  Solar cells work quite well on clear sunny winter days at temperatures well below zero degrees centigrade. Snow is bad for corn.


Fuel consumption used in energy production:

Solar panels require no fuel. per BTU.  Tractors, trucks, and other farm equipment uses significant quantities of high grade diesel in the production ethanol. 

An Acre producing 122 bushels consumes:

Diesel            6.85 gallons
Gasoline        3.4 gallons
LPG                3.42 gallons
Natural Gas    246 cubic feet
Electricity    34 kWh

122 bushels of corn = 305 gallons ethanol = 23.2 million BTU.


Net Energy Balance:

Grinding and fermenting corn requires lots of energy also. Much of this energy is derived from coal.  Some past studies have indicated that ethanol production used more energy in the form of coal, diesel, gasoline, electricity, etc. than was produced in ethanol.  That is to say these studies claimed the net energy balance was less than 1.00.  A July 1995 study claims that process improvements have increased the Net Energy Balance to 1.24.

" We conclude that the net energy value of corn ethanol has become positive in recent years due to technological advances in ethanol conversion and increased efficiency in farm production.  We show that corn ethanol is energy efficient as indicated by an energy ratio of 1.24."

From: United States Department of Agriculture
Agricultural Economic Report No. 721


Comparison of Corn and Silicon Solar Collectors


Solar Panel with area equal to 1 Acre:

10 watts per square foot for ten hours a day = 100 watt hours per square foot per day or 36.5 kilowatt hour per square foot per year.  

Kilowatt hours per acre year = 36.5 X 43560 = 1589940
Megawatt hours per acre year = 1590
BTU per acre year = 1590 X 3414000 = 5.43 Billion. 


Solar Panel Btu output (electricity) to corn Btu value (ethanol): 

5.43 Billion Btu/23.2 million Btu= 234

Of course the United States has millions of acres of farm land producing corn and very few acres of solar panels sitting in warehouses.  Their are plenty of home roofs in Arizona and other sunny places that don't have solar collectors.  Desert roofs make better structures for solar collectors than farm land that is subject to dust storms, snow, or flooding.

Thus, producing ethanol for cars that use it, rather than producing electricity for cars that don't exist yet, with silicon or other solar collector material that is in short supply,  makes good sense. 

However,  the ratio stated above should be of interest to students who will determine our future energy policy.  Silicon is becoming cheaper and batteries are getting better every year.  So the age of the electric car is coming.  


Green House Gases:

General Electric developed huge Photovoltaic project in Europe.

" For example, this 11-megawatt solar power plant in Portugal- the world's biggest photovoltaic project - is financed and owned by Energy Financial Services.  This helps our customer Portugal's electric transmission company - meet its environmental challenges, providing electricity sufficient to power 8000 homes and saving more than 30,000 tons a year in green house gas emissions compared with equivalent fossil fuel generation."

From GE 2006 Annual Report 

11-megawatts  = 37.5 million Btu per hour.  (150 acre complex). 1 acre produces .25 million BTU per hour.

See pictures and movie, Click Here!

1 acre of corn produces 122 bushels of corn = 305 gallons ethanol = 23.2 million BTU per year.  It takes only 92.8 hours for an acre of solar panels to collect the BTU recovered from an acre of corn in a year.

Large newer nuclear power plants have output around 1000-megawatts. Just added that for comparison purposes.

We must also recognize only one fifth of the energy in ethanol  is renewable and reduces green house gases. The Net Energy Gain of 1.24 discussed above indicates much energy from coal, gasoline, diesel etc. is expended in the production of ethanol; therefore, lots of carbon dioxide is created from non-renewable fuels.    

"We conclude that the NEV of corn ethanol is positive when fertilizers are produced by modern processing plants, corn is converted in modern ethanol facilities, farmers achieve normal corn yields, and energy credits are allocated to co products. Our NEV estimate of 16,193 Btu/gal can be considered conservative, since it was derived using the replacement method for valuing coproducts, and it does not include energy credits for plants that sell carbon dioxide. Corn ethanol is energy efficient, as indicated by an energy ratio of 1.24, that is, for every Btu dedicated to producing ethanol, there is a 24-percent energy gain. Moreover, producing ethanol from domestic corn stocks achieves a net gain in a more desirable form of energy. Ethanol production utilizes abundant domestic energy supplies of coal and natural gas to convert corn into a premium liquid fuel that can replace petroleum imports by a factor of 7 to 1."

From: United States Department of Agriculture
Agricultural Economic Report No. 721

Efficient Ethanol Plants generate their own electricity by burning coal to produce high pressure steam to input to turbine/generator and use heat in exhaust steam from turbine in the fermenting process.  



Main Reference

Estimating the Net Energy Balance of Corn Ethanol

An Economic Research Service Report
by Hosein Shapouri, James A. Duffield and Michael S. Graboski
{United States Department of Agriculture
Agricultural Economic Report Number 721
July 1995}

















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...   

continue reading  center column


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.





Send Comments to