|
|
| (14 intermediate revisions by 5 users not shown) |
| Line 1: |
Line 1: |
| | = Overview<br/> = | | = Overview<br/> = |
| | | | |
| − | To prepare the cereals for further processing, the chaff has to be separated from grain, either manually with a winnowing tray or mechanically by a powered shaker or grinder. Mechanical power is also available for dehusking rice or shelling maize as an alternative to manual work with rice hullers or huskers and maize shellers. The same applies to other cereals and crops for which special machinery has been or is being developed. Bran as a by-product of dehulling cereals is a source of income if sold as poultry feed and other animal feed.<br/>Milling transforms grain into flour for food preparation. The main crops that are milled are maize, rice, sorghum, teff and millet, using hammer or plate mills. A hammer mill crushes aggregate material into smaller pieces with hammers (beaters) made from hardened alloy steel which are rectangular for efficient grinding. Hammer mills are also used to pulverise by-products of coconuts (copra), palm kernels & other oil seeds (press cake). Wheat is milled with roller mills but these are too expensive for small-scale operations. Although demand may be highest during the harvest season, grain milling is required throughout the year as many households keep a stock of grain<br/>Most operations utilise energy derived from mechanical power, with many alternatives for technologies powered by human, animal, water or a stationary engine. Mechanised milling operations are far more efficient and far less labour intensive than manual methods, using wind/micro-hydro and hybrid power systems (wind/hydro/diesel) for energy intensive processing activities. Mills can be powered directly by transforming energy from sources such as wind or water or by electricity generated from a combination of fossil fuel-fired generators with wind or hydro power. Without electricity, grain mills are often driven by diesel motors, for example, in the so-called multi-functional platforms. | + | To prepare the cereals for further processing, the chaff has to be separated from grain, either manually with a winnowing tray or mechanically by a powered shaker or grinder. Mechanical power is also available for dehusking rice or shelling maize as an alternative to manual work with rice hullers or huskers and maize shellers. The same applies to other cereals and crops for which special machinery has been or is being developed. Bran as a by-product of dehulling cereals is a source of income if sold as poultry feed and other animal feed.<br/> |
| | | | |
| | + | <br/>Milling transforms grain into flour for food preparation. The main crops that are milled are maize, rice, sorghum, teff and millet, using hammer or plate mills. A hammer mill crushes aggregate material into smaller pieces with hammers (beaters) made from hardened alloy steel which are rectangular for efficient grinding. Hammer mills are also used to pulverise by-products of coconuts (copra), palm kernels & other oil seeds (press cake). Wheat is milled with roller mills but these are too expensive for small-scale operations. Although demand may be highest during the harvest season, grain milling is required throughout the year as many households keep a stock of grain<br/> |
| | | | |
| | + | <br/>Most operations utilise energy derived from mechanical power, with many alternatives for technologies powered by human, animal, water or a stationary engine. Mechanised milling operations are far more efficient and far less labour intensive than manual methods, using wind/micro-hydro and hybrid power systems (wind/hydro/diesel) for energy intensive processing activities. Mills can be powered directly by transforming energy from sources such as wind or water or by electricity generated from a combination of fossil fuel-fired generators with wind or hydro power. Without electricity, grain mills are often driven by diesel motors, for example, in the so-called multi-functional platforms. |
| | + | |
| | + | <br/> |
| | | | |
| | = Technologies = | | = Technologies = |
| Line 12: |
Line 16: |
| | *concerning the way the motor is driven | | *concerning the way the motor is driven |
| | | | |
| − | | + | <br/> |
| | | | |
| | == Mill Technologies<br/> == | | == Mill Technologies<br/> == |
| Line 18: |
Line 22: |
| | Hammer mills etc. | | Hammer mills etc. |
| | | | |
| − | | + | <br/> |
| | | | |
| | == Drive Technologies<br/> == | | == Drive Technologies<br/> == |
| Line 26: |
Line 30: |
| | These are the so-called « solar » grain mills. For the sake of this article, a solar grain mill is a grain mill that is driven by direct current. The grain mill is used in a solar system that consists of the basic components (PV panels, batteries, charge controller, load). Common voltage levels are 12 V and 24 V. | | These are the so-called « solar » grain mills. For the sake of this article, a solar grain mill is a grain mill that is driven by direct current. The grain mill is used in a solar system that consists of the basic components (PV panels, batteries, charge controller, load). Common voltage levels are 12 V and 24 V. |
| | | | |
| − | [[File:Dc grain mill with mill operator.JPG|thumb|right|DC grain mill with mill operator. This specific device is used for millet.]]<u>Advantages:</u> | + | [[File:Dc grain mill with mill operator.JPG|thumb|right|180px|DC grain mill with mill operator. This specific device is used for millet.]]<u>Advantages:</u> |
| | | | |
| − | *General advantages of decentralised solar systems: usable wherever the resource is available, can be sized to the need, etc. | + | *General advantages of decentralised [[Solar Home Systems (SHS)|solar systems]]: usable wherever the resource is available, can be sized to the need, etc. |
| | | | |
| | <u>Disadvantages:</u> | | <u>Disadvantages:</u> |
| Line 39: |
Line 43: |
| | *Requires battery maintenance. | | *Requires battery maintenance. |
| | | | |
| | + | {{#widget:YouTube|id=xWgevfqIvdU|height=400|width=800}} |
| | | | |
| | | | |
| Line 47: |
Line 52: |
| | In addition, these grain mills can also be driven with solar energy. This use case would require an inverter and batteries. | | In addition, these grain mills can also be driven with solar energy. This use case would require an inverter and batteries. |
| | | | |
| − | | + | <br/> |
| | | | |
| | === Diesel-driven Grain Mills<br/> === | | === Diesel-driven Grain Mills<br/> === |
| Line 53: |
Line 58: |
| | These can, for example, be found in multi-functional platforms. In this case, the diesel motor drives the grain mill via a transmission drive. | | These can, for example, be found in multi-functional platforms. In this case, the diesel motor drives the grain mill via a transmission drive. |
| | | | |
| | + | <br/> |
| | | | |
| | + | === Direct drive Grain Mill<br/> === |
| | + | |
| | + | Grain mills can also be power by the pure rotational power of a water turbine. |
| | + | |
| | + | <br/> |
| | | | |
| | = Practical Experiences = | | = Practical Experiences = |
| Line 65: |
Line 76: |
| | One of the first conclusion of the project was to not underestimate the amount of work necessary in the beginning to make the productive use work. | | One of the first conclusion of the project was to not underestimate the amount of work necessary in the beginning to make the productive use work. |
| | | | |
| − | -> Please see a presentation [http://energypedia.info/index.php/File:GIZ_Im_Abseits_der_Netze_012011_Senegal_Peracod_PU_Wegener.pdf here] on some issues with solar grain mills in Senegal.
| + | ► Please see a presentation [[:File:GIZ Im Abseits der Netze 012011 Senegal Peracod PU Wegener.pdf|here]] on some issues with solar grain mills in Senegal. |
| | | | |
| | + | ► [[Senegal Energy Situation|Senegal Energy Situation]] |
| | | | |
| | + | <br/> |
| | | | |
| | = Pitfalls = | | = Pitfalls = |
| Line 77: |
Line 90: |
| | *In addition, grain may become hot in the grain mill and thus change its taste. | | *In addition, grain may become hot in the grain mill and thus change its taste. |
| | | | |
| − | | + | <br/> |
| | | | |
| | == Types of Grain that can be Milled<br/> == | | == Types of Grain that can be Milled<br/> == |
| | | | |
| − | Grain mills must be adapted to the type of product to be milled. There are several grain mills which can be adapted to different goods, for example, wheat, maize, or sorghum. Be careful when choosing a product and test it before deployment. | + | {| cellspacing="1" cellpadding="5" border="0" style="width: 100%" |
| | + | |- |
| | + | | Grain mills must be adapted to the type of product to be milled. There are several grain mills which can be adapted to different goods, for example, wheat, maize, or sorghum. Be careful when choosing a product and test it before deployment. |
| | + | | |
| | + | [[File:Millet before and after milling.JPG|thumb|right|124px|Millet before and after milling]] |
| | + | |
| | + | |} |
| | | | |
| − | [[File:Millet before and after milling.JPG|thumb|right|Millet before and after milling]]
| + | <br/> |
| | | | |
| | == Improper Sizing<br/> == | | == Improper Sizing<br/> == |
| | | | |
| − | When designing the system, one should take care of proper sizing of the mill and the associated power system. <u>Key questions to be considered include:</u> | + | When designing the system, one should take care of proper sizing of the mill and the associated power system. |
| | + | |
| | + | <u>Key questions to be considered include:</u> |
| | | | |
| | *What is the amount of grain that has to be milled on average, and in peak times? Can my (diesel / solar) system power the mill for a sufficient amount of time? | | *What is the amount of grain that has to be milled on average, and in peak times? Can my (diesel / solar) system power the mill for a sufficient amount of time? |
| Line 95: |
Line 116: |
| | Answering these questions will require technical / engineering knowledge (system design etc.), but also knowledge of people's habits. | | Answering these questions will require technical / engineering knowledge (system design etc.), but also knowledge of people's habits. |
| | | | |
| − | | + | <br/> |
| | | | |
| | = Impact = | | = Impact = |
| Line 101: |
Line 122: |
| | Grain milling can greatly ease workload on women, as women are usually in charge of milling by hand with the help of a mortar and pestle. | | Grain milling can greatly ease workload on women, as women are usually in charge of milling by hand with the help of a mortar and pestle. |
| | | | |
| | + | <br/> |
| | + | |
| | + | |
| | + | = Further Information = |
| | + | |
| | + | *[[Portal:Water and Energy for Food|Water and Energy for Food (WE4F) portal on energypedia]] |
| | + | *[[Publication_-_Solar_Milling:_Exploring_Market_Requirements_to_Close_the_Commercial_Viability_Gap|Publication - Solar Milling: Exploring Market Requirements to Close the Commercial Viability Gap]]<br/> |
| | + | |
| | + | <br/> |
| | | | |
| | | | |
| Line 107: |
Line 137: |
| | <references /> | | <references /> |
| | | | |
| | + | [[Category:Impacts]] |
| | [[Category:Agriculture]] | | [[Category:Agriculture]] |
| | [[Category:Senegal]] | | [[Category:Senegal]] |
| | + | [[Category:Powering_Agriculture]] |
| | + | [[Category:Productive_Use]] |
| | [[Category:Lessons_Learned]] | | [[Category:Lessons_Learned]] |
To prepare the cereals for further processing, the chaff has to be separated from grain, either manually with a winnowing tray or mechanically by a powered shaker or grinder. Mechanical power is also available for dehusking rice or shelling maize as an alternative to manual work with rice hullers or huskers and maize shellers. The same applies to other cereals and crops for which special machinery has been or is being developed. Bran as a by-product of dehulling cereals is a source of income if sold as poultry feed and other animal feed.
These are the so-called « solar » grain mills. For the sake of this article, a solar grain mill is a grain mill that is driven by direct current. The grain mill is used in a solar system that consists of the basic components (PV panels, batteries, charge controller, load). Common voltage levels are 12 V and 24 V.
Technically, one could solve this problem by including a shunt that is governed by the load contact of the charge controller and that disconnects the mill as soon as the charge controller switches off the load. However, DC shunts are very expensive.
These are grain mills which are operated at 230 V. Basic models can be found with suppliers of agricultural equipment. These grain mills can be operated on the national grid or on minigrids.
In addition, these grain mills can also be driven with solar energy. This use case would require an inverter and batteries.
These can, for example, be found in multi-functional platforms. In this case, the diesel motor drives the grain mill via a transmission drive.
PERACOD currently has two DC-driven grain mills in operation. These grain mills were bought locally. After initially receiving quotes for a product that seemed suitable, another product had to be bought since the provider could not deliver the product the project had originally aimed at.
After installation, problems occurred with the starting resistor, which broke and had to be replaced several times. Also, users manipulated the system, leading to several failures. The grain mills have had a disappointed performance ever since installation. A detailed technical monitoring is under way in order to study the problem further.
One of the first conclusion of the project was to not underestimate the amount of work necessary in the beginning to make the productive use work.
When designing the system, one should take care of proper sizing of the mill and the associated power system.
Answering these questions will require technical / engineering knowledge (system design etc.), but also knowledge of people's habits.
Grain milling can greatly ease workload on women, as women are usually in charge of milling by hand with the help of a mortar and pestle.
