Introduction
Dendro power is the generation of electricity from sustainably grown biomass (fuel wood). It is
particularly well suited to tropical countries such as Sri Lanka as the fuel wood can be grown
rapidly and coppiced once or twice a month. Dendro using sustainably grown fuel wood can be
effectively used to replace the use of fossil fuels for electricity generation and it can also deliver
many other socioeconomic and environmental benefits.
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Dendro Power
Dendro power has great potential as a long term power generation option, both for grid-connected
generation and for off-grid communities. Solar and village hydro power only have the potential to
meet the energy needs of around 15-20% of the off-grid population in the country and Village
Dendro Schemes can be constructed to serve off-grid communities that do not have the hydro
potential and are unable to afford solar. Dendro power is a community-based electricity generating
technology that includes all households in a village irrespective of their income level.
Dendro power could also be an option to replace government plans for fossil fuel power plants with
sustainable renewable energy options. As the first step Energy Forum is keen to establish a grid
connected dendro power plant with an out-grower system for fuel wood supply.
The Process
The dendro power generation process consists of three steps:
1. Growth of dedicated forests with fast growing tree species, having high energy yield.
2. Regular harvesting of biomass from the forest using coppicing techniques i.e. the tree as a
whole is not cut down, but pruned systematically.
3. Biomass is transported and fed into the furnace of the conventional steam turbine/generator or
fed into a gasifier to produce a combustible gas that could be burnt in a diesel engine coupled to
an electrical generator.
Environmental Benefits of Dendro Power
• Biomass is a renewable energy source which is almost carbon neutral as the carbon emissions
released during combustion are recaptured during re-growth. However in practice not all biomass
generation will be carbon neutral as transportation to the generation plant will generate carbon
emissions. Nevertheless, with the rising importance of reducing carbon emissions and addressing
climate change, biomass is becoming recognised as a feasible fuel substitute for conventional
energy sources.
• The leaves of the Gliricidia Sepium tree can also be used as cattle feed or as a substitute for urea
as a soil nutrient.
Environmental Impact
Wood-fired biomass power plants produce some air and water pollution. The grinding or chipping of wood creates dust, although
wetting the wood before chipping can reduce dust levels. Furthermore, burning wood releases volatile organic compounds, or
VOCs, which pose a health risk.41 The amount of air pollutants, including NOX and SO2, emitted by wood burning power plants
is significantly lower than those emitted by plants using coal.42
Power Generation
In the most common method of electricity generation from biomass, wood waste is burned in a manner similar to coal or gas
firing in a power plant. The waste is sent through a chipper and then to a boiler where it is burned to heat water, producing steam.
The resulting steam spins turbines, which in turn drive generators to produce electricity (Exhibit 15-2). In co-firing, fossil fuels
and wood waste are burned together to create steam. The wood waste may need to be dried prior to burning to reduce its moisture
content.
The wood-fired biomass power plant proposed for Sacul, a small town near Nacogdoches, will employ a fluidized bed
combustion boiler (FBC).21 In an FBC, a layer of sand is heated and agitated using upflowing jets of air. The heated sand is used
to distribute air evenly throughout the chamber. Wood waste then is injected into the boiler. The jets of air suspend the wood in
midair, allowing it to burn on all sides, yielding a more efficient combustion process. 22