Cofiring is the easiest and fastest entry point for coal
power plants that will enter the renewable energy sector. With the cofiring
mechanism, the percentage of biomass can be increased gradually, even later it
is possible if 100% of the power plant's fuel uses biomass. Biomass itself,
especially from plants, is a renewable energy source, but if managed properly. Sources
of biomass that are obtained carelessly and without regard to environmental
aspects are not renewable energy and it will not be sustainable. These
activities are contrary to the concept of bioeconomy. And in Indonesia in
particular the use of energy from biomass, especially PKS is also in line with
government policy which is to encourage the renewable energy mix by 5% in 2025
based on Presidential Regulation No. 5 of 2006. Besides the cofiring method is
also listed in the RUKN (National Electricity General Plan) 2019- 2038 which
states that the energy conservation roadmap for energy supply activities one of
which includes an energy efficiency improvement program on its own use and
cofiring.
Among the various biomass sources currently available, PKS (palmkernel shell) is the best biomass fuel. That is because PKS has properties that
are close to wood pellets and even in the international biomass fuel market,
PKS is the main competitor of wood pellets. PKS has a relatively uniform shape
and size, high calories, high bulk density, low ash content and is available in
abundant quantities. PKS is palm oil mill (CPO mill) waste so there is no need for complicated production
processes such as wood pellets. It is estimated that there are more than 10
tons / month of PKS produced in Indonesia. Then what about other biomass fuels?
Below is a brief comparison with a number of other biomass fuels, namely wood
pellets, wood chips, biomass pellets and rice husks.
Wood Pellet
wood pellets have a density of around 700 kg / m3 from the
compaction process (wood powder / sawdust densification). In quality wood
pellets are better than PKS, this is mainly due to the uniform shape and high
level of dryness. Lack of wood pellets is in the price and volume factors. In
Indonesia, the price of wood pellets is around 2 times PKS and 3 times coal.
Even though the quality is better, with this price, coal power plants certainly
will not use a large percentage for cofiring, especially if there are also a
number of technical factors as a limitation, such as combustion technology
used, chemical ash in wood pellets and so on. Another factor is the volume of
availability of wood pellets themselves, which currently produce in Indonesia
is still small, which is estimated to be less than 100,000 tons / year. If
there is a surge in demand, the selling price of wood pellets increases,
following market laws. But with low wood pellet production volumes and
relatively expensive prices, wood pellets are less suitable for cofiring.
Wood Chip
Wood chip is a very simple form of biomass fuel, which is
made only by size reduction process by using a wood chipper machine. The main
problem with wood chips is that they have low bulk density and are expensive to
transport. Bulk density wood chip is only about 1/4 of wood pellet or 1/3 PKS.
The quality of the wood chip will be exactly the same as the quality of the
wood used. Wood chips are only economical if the source of wood chip raw
materials is close to the power plant. In simple words if the power plant is
surrounded by energy plantation as a source of wood chips, it is probable that
the supply of wood chips to the plant will be economical. The energy plantation
can also be integrated with livestock businesses. To optimize the potential of
the energy plantation, for more details, please read here.
Biomass Pellet /
Agro-Waste Pellet
Biomass pellets or pellets from agricultural waste
(agro-waste pellets) can also be used to fuel the power plant. These
agricultural waste pellets include empty fruit bunch pellets (EFB pellets),
rice husk pellets (RH pellets), corn cobs pellets and so on. The quality of the
agricultural waste pellets is below wood pellets and it also seems that the
producers of these pellet types are still very limited or do not even exist yet
in Indonesia. And because it requires industry for its production, the selling
price of agro-waste pellets predicted will not too different from wood pellets.
Rice Husk
Rice husks are widely available in rice farming centers or
rice barns. Rice husk also has small bulk density (around 100 kg / m3), small
caloric value and high ash content can even reach 20%. It also makes it less
economical if rice husks are transported over long distances. Another factor is
the high level of drought in rice husks so that they are prone to fires that
are piled on their storage. Rice husk always comes from dry grain, because the
rice milling process can only be done on dry rice. Other technical factors such
as high ash content will affect the portion of rice husk use.
Based on the above comparison, it seems that PKS or palm
kernel shells are the ideal biomass fuel for cofiring or fullfiring (100% PKS)
at the coal powerplant. PKS consumption for the country is estimated to
continue to increase and there will even be competition with the export market.
In these conditions it could be a number of export restrictions carried out on
the grounds of priority domestic needs.
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