Woodchips - AbsoluteAstronomy.com

Woodchips are a medium-sized solid material made by cutting, or chipping, larger pieces of wood

Wood

Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...

. Woodchips may be used as a biomass

Biomass

Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....

solid fuel

Solid fuel

Solid fuel refers to various types of solid material that are used as fuel to produce energy and provide heating, usually released through combustion....

. They may also be used as an organic mulch

Mulch

In agriculture and gardening, is a protective cover placed over the soil to retain moisture, reduce erosion, provide nutrients, and suppress weed growth and seed germination. Mulching in gardens and landscaping mimics the leaf cover that is found on forest floors....

in gardening

Gardening

Gardening is the practice of growing and cultivating plants. Ornamental plants are normally grown for their flowers, foliage, or overall appearance; useful plants are grown for consumption , for their dyes, or for medicinal or cosmetic use...

, landscaping

Landscaping

Landscaping refers to any activity that modifies the visible features of an area of land, including:# living elements, such as flora or fauna; or what is commonly referred to as gardening, the art and craft of growing plants with a goal of creating a beautiful environment within the landscape.#...

, restoration ecology

Restoration ecology

-Definition:Restoration ecology is the scientific study and practice of renewing and restoring degraded, damaged, or destroyed ecosystems and habitats in the environment by active human intervention and action, within a short time frame...

and mushroom

Mushroom

A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus; hence the word "mushroom" is most often applied to those fungi that...

cultivation. According to the different chemical and mechanical properties of the masses, the wood logs are mostly peeled, and the bark chips and the woodchips processed in different processes.

Woodchips are made in the process of woodchipping

Woodchipping

Woodchipping is the act and industry of chipping wood for pulp, processed wood products, and mulch.-Papermaking:Timber is converted to woodchips and sold, primarily, for pulp production used in paper manufacture...

with a woodchipper

Woodchipper

A tree chipper or wood chipper is a machine used for reducing wood into smaller parts, such as wood chips or sawdust. They are often portable, being mounted on wheels on frames suitable for towing behind a truck or van. Power is generally provided by an internal combustion engine from to...

Woodchips as raw material

Woodchips are used primarily as a raw material for technical wood processing. In industry, processing of bark chips is often separated after peeling the logs due to different chemical properties.

Woodchips Sources

Waste wood and residuals from construction
Construction
In the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of human multitasking...

, agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

, landscaping
Landscaping
Landscaping refers to any activity that modifies the visible features of an area of land, including:# living elements, such as flora or fauna; or what is commonly referred to as gardening, the art and craft of growing plants with a goal of creating a beautiful environment within the landscape.#...

, logging
Logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...

, and sawmills
Sawmill
A sawmill is a facility where logs are cut into boards.-Sawmill process:A sawmill's basic operation is much like those of hundreds of years ago; a log enters on one end and dimensional lumber exits on the other end....

.
Locally grown and harvested fuel crops

Possible Methods of Woodchip Conveyance

Pneumatic
Conveyor belt
Conveyor belt
A conveyor belt consists of two or more pulleys, with a continuous loop of material - the conveyor belt - that rotates about them. One or both of the pulleys are powered, moving the belt and the material on the belt forward. The powered pulley is called the drive pulley while the unpowered pulley...
Hopper
Hopper
Hopper may refer to:-Mechanical parts:* A general term for a chute with additional width and depth for temporary storage* Hopper , a large container used for dust collection* Part of a combine harvester...

with direct chute
Batch system (manual conveyance)

As mulch

Woodchips are frequently the byproduct of pruning of trees. When used as a mulch

Mulch

or Woodchip Mulch at least three inches thick, they conserve soil moisture, moderate soil temperature and suppress weed growth. In climates conducive to growing trees woodchips are readily produced, and may even be available for no additional cost beyond transport.

As Playground surfacing

Woodchips can be reprocessed into an extremely effective playground surfacing material, or impact-attenuation surface. Playground Woodchip when used as a Playground surfacing

Playground Surfacing

A playground surface is whatever material lies under and around swings, slides, monkey bars, and other playground equipment. Some surfaces are designed specifically with low cost, aesthetics, child safety, and/or wheelchair accessibility in mind....

(soft fall, cushion fall or play chip as it is sometimes known) can be very effective in lessening the impact of falls from playground equipment. When spread to depths of one foot (30 centimeters) playground woodchip can be effective at reducing impacts in falls up to 11 feet (3 meters).http://www.standards.co.nz/news/Media+archive/Jan+-+March+06/Minimising+Playground+Accidents.htm Playground woodchip is also an environmentally friendly alternative to rubber type playground surfaces.

As fuel

Traditional use of woodchips is as a solid fuel for heating in buildings or in energy plants for generating electric power

Electric power

Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...

from renewable energy

Renewable energy

Renewable energy is energy which comes from natural resources such as sunlight, wind, rain, tides, and geothermal heat, which are renewable . About 16% of global final energy consumption comes from renewables, with 10% coming from traditional biomass, which is mainly used for heating, and 3.4% from...

.

The newer fuel systems for heating use either woodchips or wood pellets. The advantage of woodchips is cost, the advantage of wood pellets is the controlled fuel value. The use of woodchips in automated heating systems, is based on a robust technology.

In a number of cases, coal power plants have been converted to run on woodchips. This is fairly straightforward to do, since they both use an identical steam turbine

Steam turbine

A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884....

heat engine

Heat engine

In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work. It does this by bringing a working substance from a high temperature state to a lower temperature state. A heat "source" generates thermal energy that brings the working substance...

, and the cost of woodchip fuel is comparable to coal

Coal

Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

.

Solid biomass

Biomass

is an attractive fuel for addressing the concerns of the energy crisis

Energy crisis

An energy crisis is any great bottleneck in the supply of energy resources to an economy. In popular literature though, it often refers to one of the energy sources used at a certain time and place, particularly those that supply national electricity grids or serve as fuel for vehicles...

and climate change

Climate change

Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

, since the fuel is affordable, widely available, and is carbon neutral

Carbon neutral

Carbon neutrality, or having a net zero carbon footprint, refers to achieving net zero carbon emissions by balancing a measured amount of carbon released with an equivalent amount sequestered or offset, or buying enough carbon credits to make up the difference...

and sustainable as long as the crops are allowed to regrow. In most cases, biomass is not carbon neutral as wood is not regrown and the efficiency of biomass operations produce more pollutants than the processes they replace. Compared to coal and nuclear fuels, woodchip biomass does not have waste disposal issues, since wood ash

Wood ash

Wood ash is the residue powder left after the combustion of wood. Main producers of wood ash are wood industries and power plants.-Composition:...

can be used directly as a mineral-rich plant fertilizer

Fertilizer

Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...

. The fertilizer argument is misleading, however, since the minerals are removed from the fertile fields where the trees grow. If the minerals are not returned, the yields from these fields decrease and therefore more greenhouse gas is produced.

Automated Handling of Solid Fuel

Unlike the smooth, uniform shape of manufactured wood pellets

Wood pellets

Wood pellets are a type of wood fuel, generally made from compacted sawdust or other wastes from sawmilling and other wood products manufacture, but also sometimes from sources such as whole-tree removal or tree tops and branches leftover after logging and which otherwise help replenish soil...

, woodchip sizes vary and are often mixed with twigs and sawdust. This mixture has a higher probability of jamming in small feed mechanisms. Thus, sooner or later, one or more jams is likely to occur. This reduces the reliability of the system, as well as increasing maintenance costs. Despite what some pellet stove manufacturers may say, researchers whom are experienced with woodchips, say they are not compatible with the 2 inch (5 cm) auger used in pellet stoves.

Micro Combined heat and power

Wood is occasionally used to power engines, such as steam engines, Stirling engines, and Otto engines running on woodgas. As of 2008, these systems are rare, but as technology and the need for it develops, it is likely to be more common in the future. For the time being, wood can be increasingly used for heating applications. This will reduce the demand for heating oil, and thereby allow a greater percentage of fuel oil to be used for applications such as internal combustion engines, which are less compatible with wood based fuel and other solid biomass fuels. Heating applications generally do not require refined or processed fuels, which are almost always more expensive.

Comparison to other Fuels

Woodchips are less expensive than wood pellets
Wood pellets
Wood pellets are a type of wood fuel, generally made from compacted sawdust or other wastes from sawmilling and other wood products manufacture, but also sometimes from sources such as whole-tree removal or tree tops and branches leftover after logging and which otherwise help replenish soil...

. Also, woodchips are theoretically more energy efficient than pellets, because less energy is required for manufacturing, processing, and transportation; however, this assumes that they are consumed in an appropriately designed burner, and as of 2008, these are mostly only available in large systems designed for commercial/institutional use. In contrast to the lack of residential systems, commercial heating installations have been very successful in terms of performance, cost, reliability, and efficiency. http://www.biomasscenter.org/pdfs/Wood-Chip-Heating-Guide.pdf

Woodchips are also less expensive than cordwood, because the harvesting is faster and more highly automated. Also there is a greater supply, partly because all parts of a tree can be chipped, whereas small limbs and branches can require too much labor to be worth converting to cord wood. Woodchips are similar to wood pellet, in that the movement and handling is more amenable to automation than cord wood, particularly for smaller systems. Cordwood generally needs to be "seasoned" or "dry" before it can be burned cleanly and efficiently. On the other hand, woodchip systems are typically designed to cleanly and efficiently burn "green chips" with very high moisture content of 43-47% (wet basis). (see gasification

Gasification

Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen, carbon dioxide and methane. This is achieved by reacting the material at high temperatures , without combustion, with a controlled amount of oxygen and/or steam...

and woodgas)

Environmental Issues

If woodchips are harvested through sustainable forestry practices, then this is considered a source of renewable energy

Renewable energy

.
On the other hand, it is clear that some harvesting practices, such as clearcutting large areas, are often highly damaging to forest

Forest

A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

ecosystem

Ecosystem

An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

s.

Theoretically, whole-tree chip harvesting does not have as high a solar energy efficiency, as compared to
short rotation coppice

Short rotation coppice

Short Rotation Coppice is coppice grown as an energy crop. This woody solid biomass can be used in applications such as district heating, electric power generating stations, alone or in combination with other fuels.- Species used :...

; however, it can be an energy-efficient and low-cost method of harvesting. In some cases this practice may be controversial when whole-tree harvesting may often associated with clear cutting, and perhaps other questionable forestry practices.

Woodchips for waste processing

Bark chips, not woodchips, are used as a bulking agent in industrial composting of municipal biodegradeable waste, particularly biosolids.

Woodchip biomass does not have the waste disposal issues of coal and nuclear power, since wood ash can be used directly as a mineral-rich plant fertilizer.

Forest Fire Prevention

Woodchip harvesting can be used in concert with creating man made firebreak

Firebreak

A firebreak is a gap in vegetation or other combustible material that acts as a barrier to slow or stop the progress of a bushfire or wildfire. A firebreak may occur naturally where there is a lack of vegetation or "fuel", such as a river, lake or canyon...

s, which are used as barriers to the spread of wildfire

Wildfire

A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...

. Undergrowth coppice is ideal for chipping, and larger trees may be left in place to shade the forest floor and reduce the rate of fuel accumulation.

Market Products, Supply and Demand

Currently, domestic or residential sized systems are not available in products for sale on the general market. Homemade devices have been produced, that are small-scale, clean-burning, and efficient for woodchip fuels. Much of the research activity to date, has consisted of small budget projects that are self-funded. The majority of funding for energy research has been for liquid biofuels.

Woodchip prices in the United States

"Wood chip costs usually depend on such factors as the distance from the point of delivery, the type of material (such as bark, sawmill residue or whole-tree chips), demand by other markets and how the wood fuel is transported. Chips delivered directly to the (powerplant) station by truck are less expensive than those delivered ... and shipped by railcar. The range of prices is typically between $18 to $30 per (wet)-ton delivered."

In 2006, prices were $15 and $30 per wet-ton in the northeast.

In the 20 years leading up to 2008, prices have fluctuated between $60-70/oven-dry metric ton (odmt) in the southern states, and between $60/odmt and $160/odmt in the Northwest.

European Perspective

In several well wooded European countries (e.g. Austria, Finland, Germany, Sweden) wood chips are becoming an alternative fuel for family homes and larger buildings due to the abundant availability of wood chips, which result in low fuel costs. The European Union is promoting wood chips for energy production in the EU Forest action plan 2007-2011 .

External links

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.