An In-Depth Look

The science behind the Green Cone System

This section will provide extensive information on how Solarcone's Green Cone System works. To learn more about a specific product, click a topic below:

Health, Safety, and Environmental Impact


The primary function of the Green Cone System is to accelerate the natural decomposition process by raising temperatures, maintaining aerobic conditions, and encouraging the growth of micro-organisms. The system takes all household food waste, including vegetable scraps, raw and cooked meat or fish, bones, dairy products and other organic food waste such as bread and pasta.

Because of its state-of-the-art design, The Green Cone System does this while:

  • Containing food waste to prevent dispersion and eliminate odors.
  • Creating a secure barrier to human, farm animal, wild animal, pet and bird activity.
  • Preventing surface and top soil contamination.
  • Meeting all relevant health, safety and environmental legislation.

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The Green Cone is a four-part injection molded unit. It's comprised of a lower basket installed below the ground, which forms the base for an above ground double-walled solar chamber with an access lid. The design of the Green Cone uses solar heating in the double-walled chamber to facilitate and accelerate the aerobic decomposition process within the digestion basket. Therefore, the system should be installed to obtain the maximum sunlight in your backyard. The one-gallon sealable Kitchen Caddy is recommended for collecting and carrying the food waste to the Green Cone.

The diameter of the 17-inch deep digestion basket is 21.5 inches at the top and 16 inches at the bottom. A series of slots designed into the basket begin 7.5 inches below ground level and effectively remove about half of the side wall and base material. The inner and outer walls of the conical solar chamber are 4/5 inch apart, providing a gap that is open at the top and bottom of the unit. The diameter of the outer chamber reduces from 21.5 inches at its base to 11 at the lid end. The chamber is 27 inches high but when assembled and installed, the Green Cone stands 26 inches above ground level and extends 18 inches below ground level. Access is through an 8-inch diameter hole in the top of the solar chamber, which is sealed by a hinged lid with a turnbuckle security catch.

The Green Cone will dispose of more than 11 pounds of food waste a week, which is over 25% greater than that produced by the average household. The food waste is converted into water, carbon dioxide and a small amount residue, without the need for mixing or turning the waste. In a well operating system the residue will occupy the bottom 10 inches of the digestion basket after the decomposition of about a ton of food waste. Thus, after about five years this small quantity of residue must be removed and dug into the garden sub-soil.

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The decomposition of organic material is a natural process. Much of the dry weight of plants and animals is attributed to proteins. Their remains are eventually converted into soil through a continuous cycle of activity, by a wide range of interdependent organisms and micro-organisms. These organisms are organic, and are concentrated largely in the top 4 inches of the soil. With its digestion basket below the ground, the Green Cone takes advantage of this organism-rich topsoil.

The system works best in fertile, well-drained soil, which means that areas of solid rock or with a high water table are unsuitable. In heavy clay soils, drainage can be improved by using a mixture of gravel and compost around the digestion basket. Soil fertility can be enhanced by the addition of suitable natural bacteria, as described below.

The smallest and most numerous micro-organisms are bacteria, with one gram of fertile soil containing around a billion bacteria. Bacteria are unicellular micro-organisms and amongst the smallest living creatures known. There are three bacterial cell shapes, spherical (coccus), rodlike (bacillus) and spiral (spirillum). Under favorable conditions bacteria numbers grow rapidly. Some survive in a dormant or spore state when conditions are not suitable, reviving when they become favorable again.

Bacteria are grouped according to there temperature requirements for growth:

  • Psychrophiles (32° - 86°F)
  • Mesophiles (59° - 113°F)
  • Thermophiles (113° - 140°F)

Bacteria within each group exhibit specific minimum, maximum and optimum temperatures for growth. For example, mesophiles grow best in the temperature range 77° - 104°F. To ensure a healthy population of bacteria, Solarcone recommends the use of our Accelerator Powder when the system is first installed, and if the decomposition process slows because of an imbalance of organic material and bacteria.

Most bacteria grow in a near neutral environment (neither acidic nor alkaline) and without light. Atmospheric oxygen is required by some bacteria, but inhibits others. Bacteria are classified as aerobes when they require oxygen to grow and anaerobes when they cannot grow in the presence of oxygen. Facultative anaerobes do not require oxygen but can grow in its presence; obligate anaerobes are poisoned by free oxygen. Under poor oxygen conditions some micro-organisms can produce toxins that inhibit the growth of higher plants and other micro-organisms. These toxins include methane, hydrogen sulfide, phosphine, skatole, indol and various organic acids. It is for this reason that the Green Cone is designed to maintain aerobic conditions. The temperature gradients in the double walled solar chamber create air movement and ensure these ideal conditions.

In addition to bacteria, other soil micro-organisms are intimately involved in the natural decomposition process. Actinomycetes resemble both bacteria and fungi. Their spores, although similar to those of bacteria, germinate into very fine colorless threads (mycelia) that resemble those of fungi. Fungi such as molds, mildews or mushrooms are usually more variable in form than either bacteria or actinomycetes. There are also algae, which are found as motile single cells or non-motile filaments.

Soil fauna ranges from microfauna, usually defined as animals less than .004 inches long, through macrofauna to megafauna, which are the largest soil organisms. Microfauna include single-celled protozoa, some smaller nematodes, small flatworms, rotifers and tardigrades. Many microfauna only exist in the water films on the organic matter. The most common macrofauna are the small white segmented enchytraeidae that feed on fungi, bacteria and decaying matter. Soil macrofauna play a valuable role in fragmenting organic waste, thus increasing its surface area. In addition, with the help of symbiotic organisms in their guts, some also break down complex substances such as cellulose, keratin and chitin. Megafauna include the larger earthworms, which also pass both soil and organic matter through their guts. The fragmented organic waste and soil fauna excretions create an environment ideal for the growth of micro-organisms. The continuous cycle of consumption, digestion and excretion by soil fauna alternates with increases in the population of micro-organisms.

Heterotrophic soil micro-organisms, which derive their carbon and energy from organic materials are concerned mainly with the breakdown of organic matter, the carbon cycle and nitrogen fixation. Autotrophic micro-organisms, which obtain carbon from carbon dioxide and energy from the oxidation of simple organic compounds, form nitrites and nitrates and oxidize sulfur and iron compounds. Most micro-organisms produce carbon dioxide, which dissolves in water to form carbonic acid. Mineral elements such as sodium, potassium and magnesium are released to the soil during the decomposition process. The weak carbonic acid dissolves relatively insoluble soil minerals.

The different bacteria outlined above produce different enzymes, which are the protein catalysts responsible for the metabolism of organic waste. The principal enzyme types important in the decomposition of food waste are:

  • Lipases to digest the fats in foods such as dairy produce, oil and meat.
  • Amylases to digest the carbohydrates in foods such potato peelings, bread, biscuits, rice and pasta.
  • Proteases to digest the proteins in foods such meat, milk and eggs.
  • Cellulases, or cytases, to digest the cellulose in fruit and vegetable matter.

When conditions are desirable for decomposition, such as within the Green Cone, only a small residue of humic substances (consisting of lignin and protein) remains.

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Health, Safety and Environmental Impact
The Green Cone causes minimal health, safety and environmental impact. The underground digestion basket and the sealed solar chamber provide sound physical barriers to odors, insects, birds and animals. With 40% of the unit below ground, the green conical solar chamber of the system creates negligible visual impact. The Green Cone is constructed from as much recycled material as possible, and the digestion basket and inner solar chamber are made from 100% recycled plastic.

As with the handling of food and food waste, good housekeeping practices are the cornerstone of health and safety. Try not to spill or leave food uncovered in the home or elsewhere, and remember to wash your hands before and after handling food. One advantage of the Green Cone is that no third party is involved in the collection and treatment of the waste, so you always know where you food is coming from as well as where it's going. For those that prefer to consume organic and non genetically modified food, the Green Cone is an excellent way to continue the organic cycle

In use, food waste is transferred as soon as practical from the kitchen to the Green Cone, which allows food waste to be removed daily as opposed to weekly or fortnightly with a centralized collection approach. Once deposited in the below ground digestion basket, there is no possibility for unintentional access to the food waste by human activity. As with any gardening activity, particularly those involving soil or compost, gloves should be worn when removing the small amount of residue that accumulates in the digestion basket after several years of operation.

Temperatures in the solar chamber of the Green Cone reach up to 122°F for long periods during summer months. Because of these ideal conditions, indigenous microorganisms grow while harmful pathogens die, through competition for nutrients.

Due to the effectiveness of the Green Cone in controlling process bypass, the efficiency of the decomposition process itself, and the inaccessibility to animals, birds and humans, the overall health, safety and environmental risk of using the Green Cone is virtually nonexistent.

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