A compost heater (or Biomeiler) is a structure for the energetic use of

biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms biom ...

for the heating of

building A building, or edifice, is an enclosed structure with a roof and walls standing more or less permanently in one place, such as a house or factory (although there's also portable buildings). Buildings come in a variety of sizes, shapes, and funct ...

s. A method relying on biological wood oxidation was developed by

Jean Pain Jean Pain (12 December 1928 – 30 July 1981) was a Swiss-born French inventor and innovator who developed the compost heater, a compost-based bioenergy system, that produced 100% of his energy needs. He heated water to at a rate of which he ...

in the 1970s. Compost heaters are used primarily for demonstration purposes as small systems for heating a house. Local waste can be converted to energy.

Types

Compost heap

The traditional compost heater exploits the heat of a large compost heap to warm a house. This type requires a big heap, intertwined with a spiral water hose. The circulating water conducts heat to the building, where it can be fed to a heating circuit. The heap must contain at least 8,000 liters of biomass to maintain a temperature during the winter. For this purpose, chipped

wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of ligni ...

is usually piled up and a water hose is passed through it. A microbiological degradation process generates heat for up to 24 months. The heat produces hot water, which is then fed to a heating circuit. With sufficient oxygen supply, the biomass is degraded by aerobic decomposition. The activity of the microorganisms can be regulated by the

moisture Moisture is the presence of a liquid, especially water, often in trace amounts. Small amounts of water may be found, for example, in the air (humidity), in foods, and in some commercial products. Moisture also refers to the amount of water vapo ...

content.

Hot water and biogas

Pain's 'Biomeiler' combines composting with

biogas Biogas is a mixture of gases, primarily consisting of methane, carbon dioxide and hydrogen sulphide, produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste and food waste. I ...

. The raw materials of Pain's compost heap were saplings, branches and underbrush. He developed the machines that grind these materials to the proper size. One of his machines, a tractor-driven model, earned fourth prize in the 1978

Grenoble lat, Gratianopolis , commune status = Prefecture and commune , image = Panorama grenoble.png , image size = , caption = From upper left: Panorama of the city, Grenoble’s cable cars, place Saint- ...

Agricultural Fair. After Pain had ground the raw materials, Pain would construct a heap three metres high and six metres across (10 × 20 feet). The heap weighed approximately , and was mounted over a steel tank. This tank was 3/4 full of compost, which had first been steeped in water for two months. The hermetically sealed tank was connected by tubing to 24 truck tire inner tubes, gathered nearby to collect the

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ear ...

gas. The gas was distilled by washing and compressing it through small stones in water. Pain used the gas for cooking and producing electricity. He also fueled a light van. Pain estimated that of brushwood would supply the gas equivalent of . of

petrol Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic c ...

. It took about 90 days to produce of gas - enough to keep two ovens and three burner stoves going for a year. The methane-fueled combustion engine drove a generator that produced 100 watts of electricity. This charged a battery, providing the light needed. Skepticism has been leveled at Pain's estimates for methane extraction and it is not known if anyone has been able to reproduce his results. Pain's compost heaps generated hot water via of pipe buried inside the compost mound. The pipe was wrapped around the methane generator with an inlet for cold water and an outlet for hot water. The heat from the decomposing mass produced of hot water heated to — enough to meet central heating, bathroom and kitchen requirements. The heap composted for nearly 18 months, after which it was dismantled. The

humus In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Lati ...

was used to

mulch A mulch is a layer of material applied to the surface of soil. Reasons for applying mulch include conservation of soil moisture, improving fertility and health of the soil, reducing weed growth and enhancing the visual appeal of the area. A ...

soils.

Heater silo

The composting process runs in an airtight container inside a house. The heat can be radiated directly to the interiors of the house or distributed by a heating circuit. An additional water pipe can be vertically built into the silo for warming water. The silo is the central part of an in-house compost heater. In autumn the silo is filled up with fresh

, after which the silo delivers comfortable heat throughout the winter.The Compost Heater Silo project
/ref> Inlet air and outlet air provide the necessary

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as we ...

. The outlet air goes out of the house. Silo moisture is higher than in a regular compost heap. The decay process produces additional water, which is drained at the bottom of the silo. A part of this water enters the top of the silo for better distribution in the processing volume. If pumped periodically or continuously to the top to rinse through the silo, the whole system becomes a ''wet composting'' system.

References

{{reflist Composting Heating, ventilation, and air conditioning Permaculture concepts