Off-Grid Homesteading: How To Create Free Heating and Air Conditioning

By Sara Tipton

Having a constant flow of cool air in the summer is the best way to beat the heat, but with the ever-increasing energy prices, and in some states rolling blackouts, it is becoming all too clear that our power grid is not something any of us should fully rely upon. A natural option is utilizing thermal energy to heat and cool the homestead.

Off-grid options may become more useful as the costs of energy continue to rise and rolling blackouts make it difficult to rely on the power companies. Self-sufficiency is also always a great way to prepare in advance for the potential power outages that are either ongoing or long-term. Geothermal could be an excellent option, so read on for more information and the pros and cons.

GEOTHERMAL ENERGY AND HOW IT WORKS

Just a few feet below the Earth’s surface is an abundant renewable energy source called geothermal energy. This energy is produced inside the earth and can provide passive heat in winters and cool air during the summer months. Thermal energy contained in the rocks and fluid below the surface of the Earth can be found from shallow depths all the way down to several miles below the Earth’s surface. Have you ever noticed that caves always seem warmer than the outside temperature during the winter and cooler during the summer? The actual temperature of caves depends on the average annual surface temperature of the place where they´re located. Might it be possible to move that cool air from underneath the soil into your homes to provide an alternative source of cooling air or warmer air?

The Earth’s geothermal energy is collected using earth tubes placed in deep trenches that will help carry the hot or cool air to the desired destination. “ Earth tubes work by harnessing what nature provides us naturally, utilizing simple principles that allow the ambient air temperature to be cooled by at least 10 or up to 20 degrees Fahrenheit, depending on the energy efficiency of the building itself. These in-ground PVC cooling tubes are also known as air tubes, earth air tubes, a ground-coupled heat exchanger, an earth-air heat exchanger, thermal labyrinth, heat recovery ventilation, geothermal energy tubes, sustainability tubes, or a number of other terms.

Cooling tubes are an efficient way to cool a building using natural convection and thermal mass principles. They require no pumps or fans and are completely passive (no moving parts). This also means that no electricity is required to “run” them, saving energy costs for the lifetime of the building, which keeps money in your pocket and keeps your carbon footprint down. This also means this is a great way to live off the grid.  Using geothermal energy can be thought of as both natural cooling, and green cooling, simultaneously, and the principles take advantage of what nature already knows how to do.

People can use geothermal heat for bathing, heating buildings, and to generate electricity and geothermal cooling to cool their homes during the hottest times of the year.

Always keep in mind that there is no perfect renewable energy source. Each energy source has pros and cons.

ADVANTAGES OF GEOTHERMAL ENERGY

• Highly efficient heating and cooling: Because geothermal energy is all about moving heat rather than creating it, the equipment can operate at 300 to 500 percent efficiency. This means that for every unit of electricity a geothermal heat pump consumes, it moves three to five units of heat. At this rate, you can expect to save 30 to 60 percent on heating costs and 25 to 50 percent on cooling costs compared to today’s most efficient furnaces and air conditioners.
• Low environmental impact: Geothermal energy is considered the greenest power source available today. It is virtually emission-free and, unlike oil and gas furnaces, requires no combustion. Geothermal heat pumps still need electricity to operate, so pairing the equipment with solar panels is a great way to lower the environmental impact even more.
• Renewable heating and cooling: Fossil fuel supplies are rapidly running out, but geothermal energy is different. All it does is extract heat from the earth, where the temperature remains much more consistent than the air in all seasons. As long as the earth exists, geothermal energy production will be possible.
• Not weather dependent: Solar and wind power are considered renewable energy sources because they will never run out, but short-term electricity shortages can occur when the sun sets and the wind stops blowing. However, the earth is ever-present, and so is the energy it produces.
• Excellent reliability and low maintenance requirements: Geothermal heat pumps have few moving parts compared to other HVAC equipment. This reduces the chance of breakdowns and decreases maintenance costs.
• Flexible applications: Geothermal energy is appropriate for the smallest house and the largest commercial building. All you need is to have the equipment sized accurately to meet your needs.
• Quiet operation: The largest components of a geothermal heat pump are installed underground. Without the noisy fan and compressor that air conditioners and air-source heat pumps require, you get to enjoy nearly silent operation. 

DISADVANTAGES OF GEOTHERMAL ENERGY

• Higher upfront cost than other HVAC systems: The installation cost for a geothermal heat pump is a setback for some. However, with amazingly efficient performance, the investment can pay for itself in just five to 10 years.
• More suitable for new home builds: While it’s possible to install a geothermal heat pump in an existing home, retrofitting requires large-scale excavation. Installing the system during new home construction is much more feasible.
• Damage to underground components may require costly repairs: In rare instances, tree roots, shifting soil, and even rodents can damage the underground loops of a geothermal system. If this happens, repairing the equipment could be a major setback
• Isn’t Effective In Hot Humid Climates: there seems to be a consensus that earth tubes (the trenches used to move the hot and cold air) do not work well in hot humid climates without some form of dehumidification that prevents water from condensing in the earth tubes.

The following video goes into what is needed to create naturally occurring heating/cooling.

This next video describes how to install this on your homestead.

Build it Solar has a great Do-it-Yourself solar tube project. You can read more about it by clicking here. If you would like more information on installing a passive solar system, please click here. 

Have you tried to use geothermal energy? If so, what suggestions or information could you offer Ready Nutrition readers to help them make the right decisions about off-grid energy?