Editing Compost heater

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[[File:BioMeilerConcept.jpg|thumb|Using the heat of an external compost heap for warming up the inside of a house.]]

The '''compost heater''' (also '''biomeiler''') it a setup for utilization of the [[heat]] dissipation of a [[composting]] process. The thermal effect is well known from a compost heap, where the [[biomass]] is decayed by the digestion and metabolism of many different [[microbes]] and invertebrates. The heat is used, for instance, for a dwelling house.

In contrast to the production of [[biogas]], the composting process requires enough [[oxygen]], resulting in an aerobic decay. Also, water is added at the beginning to optimize the biological conditions. When the decay has started, additional water is created by the decay process itself, so the compost remains wet indefinitely. Finally, the whole biomass breaks down completely to CO2 and H2O, producing heat. However, the composting process is usually stopped at the end of winter, and the created humus is removed from the heater and used for the garden.

The french agronomist [[Jean Pain]] is held responsible for the invention of the Biomeiler. His system was a combination of a sealed biogas reactor in the center of a big compost heap, producing both biogas and heat. He also worked on agricultural principles in harmony with nature.

== Three basic types ==

=== Compost heap in the garden with water circulation system ===

{{Excerpt|Compost pile heater}}

=== Combination of hot water and biogas ===

{{Excerpt|Jean Pain system}}

=== Compost heater silo inside a building ===

{{Excerpt|Compost heater silo}}

== Calculations ==

A considerable amount of biomass (chipped wood, foliage, chopped bush) can be harvested in the garden. The annual energy of about 3860 kWh per 1000 m² is possible. The following data are from [[energy forestry]].

{| class="wikitable"
! Data for energy forestry
! Values
|-
| Harvested biomass per 1000 m²
| 0.8 to 1.2 metric tons
|-
| Energy contents of wood* per metric ton
| 3860 kWh
|-
| Energy contents of wood* per stere**
| 2100 kWh
|}

<small>* at 20% residual moisture </small>

<small>** A stere is a simple stack of loose wood in a cubic meter. The actual wood content is about 65 percent, i.e. 1 stere is about 0.65 solid cubic metre of wood. </small>

The unit ''stere'' can be used in this context directly to calculate the needed capacity of the compost heater, because the filled in biomass (for example chipped wood) contains a comparable fraction of air. 2100 kWh heat energy are, therefore, generated per m³ composting space. The residual moisture does not diminish the usable energy output and can be ignored in this case. It may vary without any impact. In contrast to a wood stove the residual moisture is not vaporized in a compost heater, so the energy conversion efficiency is not reduced.

While the heating of older dwelling houses require more than 20,000 kWh per year, the recently developed well insulated houses require less than 10000 kWh. For example, the [[House in a house|House-in-a-House]] can be easily served by a compost heater silo of the size 2000 l, making the interior of the house comfortably warm throughout the year.

== Related projects ==

{{Gallery
| instance-of = Compost heater
}}

== External links ==

* European bioconversion projects and realizations for macroalgal biomass: Saint-Cast-Le-Guildo (France) experiment, reference to Pain method of breaking down wood chips in relation to the composting of macroalgal biomass
* [http://www.motherearthnews.com/Renewable-Energy/1981-07-01/DIY-Water-Heating-Compost.aspx DIY Water Heating with Compost], article in ''Mother Earth News'' (July/August 1981)

{{Page data
| keywords = compost, heating, energy
| sdg = SDG12 Responsible consumption and production
}}

[[Category:Composting]]
[[Category:Agriculture]]
[[Category:Sustainable agriculture]]
[[Category:Waste management]]
[[Category:Green living]]
[[Category:Renewable energy]]
[[Category:Compost]]
[[Category:Energy]]