Utility Business for Palm Oil Mills

When the priority is to obtain the maximum profit, good environmental management and ease, efficiency and stability of production as an option, then utility matters at the palm oil mill may be collaborated with other parties. This specialization becomes important because of the priority choices above. The utility problems in question are electricity and steam. Electricity is produced from a steam turbine and steam is produced from a boiler. High pressure steam enters the steam turbine to drive a generator and produce electricity and low pressure steam output from the steam turbine is used for the fresh fruth bunch (FFB) sterilization process. Water treatment for boiler feed is also part of the utility problem, as well as for boiler operations to produce output in the form of electricity and steam.

Regarding cooperation or business models, palm oil mills can pay for the electricity and steam they receive. But because the fuel or energy to produce electricity and steam comes from palm oil mills, of course the price is cheaper. If currently almost all palm oil mills use their boiler fuel from mesocarp fiber and palm kernel shell (PKS), then with this specialization it is possible for palm fiber (mesocarp fiber) and empty palm fruit bunches (EFB) to be used as fuel or energy sources while palm kernel shells (PKS) can 100% sold and even exported. Palm kernel shells (PKS) as biomass fuel can be sold directly and are in great demand, and are also the main competitor for wood pellets in the global biomass fuel market.

Under these conditions, there are efforts to increase the efficiency of utility production such as steam and electricity as optimally as possible, not only combustion technology with static grates, moving grates, reciprocating grates to fluidized beds, but it is even possible to use pyrolysis. EFB or empty palm fruit bunches, which were previously unprocessed and were an environmental problem, can become a potential energy source so that 100% of the palm kernel shells / PKS from palm oil mills can be commercialized/sold. And even if the utility provider uses pyrolysis, biochar will also be obtained. Biochar provides many benefits related to soil fertility and climate.

Why Produce Electricity From Biogas Using Gas Engine Generators? Not With Gas Turbine Generators Or Steam Turbine Generators

  

The need for this type of power plant is always related to capacity, a number of technical factors and the investment costs required. Turbine with generator is a type of generator which is commonly used in industry, especially steam turbine and gas turbine. The grouping of turbine types above is based on the principle of operation and the fluid that moves them. At a palm oil mill, almost all of the electricity is generated from a steam turbine generator. In addition to electricity production, the steam generated from the boiler is also used to process fresh fruit bunches (FFB) to produce crude palm oil or CPO.

Processing of palm oil mill effluent (POME) into biogas and subsequently mostly used for power generation. Almost all of the electricity from biogas is used to meet the needs outside the palm oil mill and the surrounding community. With the potential for palm oil mills in Indonesia that are estimated at more than 1000 units supported by 15 million hectares of palm oil plantations, the potential for electricity generated will be more than 1.5 GW. Approximately 0.7 m3 of liquid waste is produced by the palm oil mill from each tonne of FFB processed. Biogas usually consists of 50-75% methane (CH4), 25-45% carbon dioxide (CO2), and a number of other gases. If wastewater management is not controlled, methane in biogas is released directly into the atmosphere. As a greenhouse gas (GHG) methane has a 21 times greater effect than CO2. The production of electricity from biogas from palm oil mill effluent (pome) is also an effort to reduce environmental hazards. The electricity production from the biogas all uses a gas engine generator and none of them uses a steam engine generator. This is because the production of electricity with steam turbines is not only more complex but also less efficient. The gas engine generator is a power plant that is most suitable for the conversion of biogas to electricity. Gas engines whose engines are similar to gasoline engines, with only the change of fuel into gas (biogas) or similar to vehicle engines such as public buses that run on gas fuel are also more familiar to most people. 

Gas turbine generators are generally used for large capacity power plants. Gas power plants in Indonesia generally use gas turbine generators. Gas turbines are equipment that uses high pressure combustion gases to turn a turbine that can be connected to a generator to generate electricity. Apart from generating power, gas turbines are also used in boats, racing cars and jet planes. The main parts of gas turbines include: compressor, combustion chamber, gas turbine and workload. Each part or segment has a number of critical components which are connected in one axis. During the operation of the gas turbine, some of the power generated by the turbine is used to drive the compressor. The large capacity and technical factors of gas turbine generators make the unit expensive and not used for the production of electricity from biogas. The electricity capacity of biogas from wastewater treatment like POME is not too large, that is, for a palm oil mill with a capacity of 30 tonnes / hour of FFB it will produce about 1 MW of electricity and its multiples. This is the reason why gas engine generators are used in biogas power plants, especially in the palm oil industry.

Cofiring Biomass at a Steam Turbine Gas Power Plant, Is It Possible?

 Cofiring technology is divided into several types, namely direct cofiring, indirect cofiring, and parallel cofiring. The choice of using the cofiring type is mainly related to the type of fuel and combustion technology used. In general, based on its form, fuel is divided into three namely solid, liquid and gas fuels. The form of the fuel affects the combustion technology used. Liquid fuel which is a fluid, then combustion with a burner. Whereas fuel for combustion technology with fixed bed, fluidized bed and pulverized combustion. Mixing solid fuels such as biomass especially PKS / palmkernel shells, wood pellets and wood chips with coal is usually done in the direct cofiring type and this is the most common cofiring type. Then how about cofiring biomass with biomass fuels that are solid form with fossil fuels that are liquid or gas?

Steam Turbine

Fossil fuels such as diesel oil and gas such as natural gas usually used to fuel power plants in internal combustion engines (IC engines) whose output is mechanical energy to drive generators. Gas engine is an IC engine that is commonly used for the production of electricity from gas fuels such as natural gas. But if diesel oil or natural gas is used on external combustion engines (EC engines) such as furnaces and boilers that produce steam. Steam will then drive the turbine that is connected to the generator. In the EC engine cofiring mechanism can be done namely parallel cofiring type. In this mechanism, biomass as will be used to produce steam for additional steam from the fossil fueled EC engine.

Avedore Power Plant, Denmark

An example of a biomass cofiring with a gas power plant is the Avedore Unit 2 power plant, which is located in Denmark near Copenhagen. The power plant operates at ultra-supercritical with a capacity of 430 MW using steam turbine with natural gas fuel and is also equipped with 2 gas turbines with a capacity of 51 MW each. The gas turbine is used to provide electricity at peak load and boiler feed water via the exhaust heat recovery unit. Whereas a biomass boiler with a capacity of around 50 MW is used to provide additional steam to the system. The biomass boiler burns straw at a consumption of 150 thousand tons per year and produces 40 kg / second of steam at 583 C and pressures up to 310 bar.