Pellet

1. What is pellet

Pellet fuels are heating fuels made from compressed biomass. Wood pellets are the most common type. A form of wood fuel, wood pellets are generally made from compacted sawdust or other wastes from sawmilling and other wood products manufacture. Other woody biomass sources include palm kernel shell, coconut shell, and whole-tree removal or tree tops and branches leftover after logging and which otherwise help replenish soil nutrients. As well grasses can also be pelletized, creating grass pellets. Pellets are manufactured in several types and grades as fuels for electric power plants, homes, and other applications in between. Pellets are extremely dense and can be produced with a low moisture content (below 10%) that allows them to be burned with a very high combustion efficiency. Further, their regular geometry and small size allow automatic feeding with very fine calibration. They can be fed to a burner by auger feeding or by pneumatic conveying. Their high density also permits compact storage and rational transport over long distance. They can be conveniently blown from a tanker to a storage bunker or silo on a customer's premises.

2. Energy output and efficiency

The energy content of wood pellets is approximately 4.7 – 5.4 kWh/Kg.
High-efficiency wood pellet boilers have been developed in recent years, typically offering combustion efficiencies of over 85%.
Wood pellet boilers have limited control over the rate and presence of combustion compared to liquid or gaseous-fired systems; however, for this reason they are better suited for hydronic heating systems due to the hydronic system's greater ability to store heat. Pellet burners capable of being retrofitted to oil-burning boilers are also available.

3. Air pollution emissions

Emissions such as NOx, SOx and volatile organic compounds from pellet burning equipment are in general very low in comparison to other forms of combustion heating. An additional consideration, though, is such air pollutant emissions caused in producing the energy used to manufacture pellets.

4. Usage by region

EUROPE
Usage across Europe varies due to government regulations. In the Netherlands, Belgium, and the UK, pellets are used mainly in large-scale power plants. In Denmark and Sweden, pellets are used in large-scale power plants, medium-scale district heating systems, and small-scale residential heat. In Germany, Austria, Italy, and France, pellets are used mostly for small-scale residential and industrial heat.

In the EU, the largest users of wood pellets are the UK, Denmark, the Netherlands, Sweden, Germany, and Belgium.

Pellets are widely used in Sweden, the main pellet producer in Europe, mainly as an alternative to oil-fired central heating. In Austria, the leading market for pellet central heating furnaces (relative to its population), it is estimated that 2/3 of all new domestic heating furnaces are pellet burners. In Italy, a large market for automatically fed pellet stoves has developed.

5. The fuel of the future

Environmental lunacy in Europe

ECONOMIST, Apr 6th 201, http://www.economist.com/news/business/21575771-environmental-lunacy-europe-fuel-future

WHITCH source of renewable energy is most important to the European Union? Solar power, perhaps? (Europe has three-quarters of the world’s total installed capacity of solar photovoltaic energy.) Or wind? (Germany trebled its wind-power capacity in the past decade.) The answer is neither. By far the largest so-called renewable fuel used in Europe is wood.

In its various forms, from sticks to pellets to sawdust, wood (or to use its fashionable name, biomass) accounts for about half of Europe’s renewable-energy consumption. In some countries, such as Poland and Finland, wood meets more than 80% of renewable-energy demand. Even in Germany, home of the Energiewende (energy transformation) which has poured huge subsidies into wind and solar power, 38% of non-fossil fuel consumption comes from the stuff. After years in which European governments have boasted about their high-tech, low-carbon energy revolution, the main beneficiary seems to be the favoured fuel of pre-industrial societies.

The idea that wood is low in carbon sounds bizarre. But the original argument for including it in the EU’s list of renewable-energy supplies was respectable. If wood used in a power station comes from properly managed forests, then the carbon that billows out of the chimney can be offset by the carbon that is captured and stored in newly planted trees. Wood can be carbon-neutral. Whether it actually turns out to be is a different matter. But once the decision had been taken to call it a renewable, its usage soared.

In the electricity sector, wood has various advantages. Planting fields of windmills is expensive but power stations can be adapted to burn a mixture of 90% coal and 10% wood (called co-firing) with little new investment. Unlike new solar or wind farms, power stations are already linked to the grid. Moreover, wood energy is not intermittent as is that produced from the sun and the wind: it does not require backup power at night, or on calm days. And because wood can be used in coal-fired power stations that might otherwise have been shut down under new environmental standards, it is extremely popular with power companies.

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