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Combustion is So 19th Century

Combustion burned bright at the end of the 19th Century, but it has a dim future in the 21st Century. Thomas Edison, one of the great innovators of the modern era and the father of combustion-powered electricity generation, put it this way over a century ago:

“Someday some fellow will invent a way of concentrating and storing sunshine to use instead of this old, absurd Prometheus scheme of fire. This scheme of combustion in order to get power makes me sick to think of it – it is so wasteful . . . We should utilize natural forces and thus get all of our power. Sunshine is a form of energy, and the winds and the tides are manifestations of energy. Do we use them? Oh no; we burn up wood and coal, as renters burn up the front fence for fuel. We live like squatters, not as if we owned the property.”

Lucky for us, we live in that age when converting sunshine to electrical power is an increasingly affordable choice. In theory, you can make any building zero net energy if you add enough solar panels, but that would not be the most cost-effective or carbon-effective strategy. In my positive energy projects, I strive to eliminate combustion in the building, then look at leveraging all the natural energy forces available to reduce the overall operational load.

Comparison chart from

Combustion creates toxic gases, including carbon monoxide, and other gases such as carbon dioxide and water vapor. These gases can have a detrimental impact on the indoor and outdoor environment. If combustion waste ventilation is missing or disrupted, such as when your kitchen range sucks the exhaust fumes from your gas water heater back down the chimney, then you can get into trouble. Combustion in a building can also escape containment and result in fire, explosion, burns, or chronic health issues.

One key way to get away from combustion is to convert from gas cooking to induction cooking. You can still be a gourmet chef but without the dangerous fumes. Another key is to convert to electric heat pumps for heating, cooling, and domestic hot water. A heat pump moves heat instead of creating heat, and the most efficient method uses the relatively constant temperature of the earth under the frost line. Ground source or geothermal heat pumps move heat from the earth in the winter and use it as a giant heat sink in the summer. They are significantly more efficient than standard gas-combustion HVAC systems and nearly twice as efficient as good air-source heat pumps.

Going vertical for geothermal heating and cooling with a zero-energy home in Bartholomew County that will tap free energy from earth and sun

Geothermal systems require a long horizontal trench or deep boreholes for piping that contains a circulating liquid to transfer heat. While geothermal heat pumps are significantly more expensive than air-source heat pumps, they also come with Federal renewable energy tax credits (26% in 2020) and utility rebates. Two recent zero energy home projects I designed saw the incentives cancel out the higher initial cost of the geothermal systems. Geothermal heat pumps can also generate significant domestic hot water by recovering waste heat from the refrigeration cycle.

By tapping into the free heating and cooling offered by the earth you can decrease the overall heating and cooling load that will be offset by a reasonable number of solar PV electric panels harvesting and storing free sunshine. You can further reduce this load with a well-insulated building envelope with careful glazing and overhang design that blocks solar heat gain in summer but allows it in winter.

Then you can stop "burning your front fence" and Edison and I will be proud of you.

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