Across Southeast Asia’s palm-oil belt, slow-rotating screw presses are turning empty fruit bunches from soggy burden to usable fuel—using only a few kilowatt-hours per tonne. The kicker: the thermal value retained and oil recovered swamp the power bill, pushing payback toward the 1–3 year range.
Industry: Palm_Oil | Process: Empty_Fruit_Bunch_(EFB)_Processing
Empty fruit bunches (EFB) account for roughly 20% of fresh fruit bunch (FFB) mass, according to academic work on palm mill co-products (www.sciencedirect.com). Mills have one primary tool to deal with the wet, bulky fiber: the screw press, a slow-rotating auger that continuously compresses EFB and expels liquid (www.simecpellet.com).
The capacity numbers read like factory-floor pragmatism. Typical single- or twin-screw machines handle about 6–12 tonne per hour (t/h) of whole EFB (wet) (news.kharisma-sawit.com). A standard “SE/SSP 50” model processes about 6 t/h; larger machines reach roughly 12 t/h (news.kharisma-sawit.com). Output fibers are coarse strands of roughly 3–8 inches (ru.scribd.com; news.kharisma-sawit.com), typically conveyed onward to a boiler or pellet mill.
In practice, large mills tend to choose either a direct screw press or a combination shredder plus press. MBL’s single-barrel design uses a 45 kW motor on a ~12 t/h feed, while an advanced Malaysian KH‑777‑12 model specifies 75 kW for ~10–12 t/h (www.simecpellet.com; ru.scribd.com). (The KH document lists Motor: YKL 75 kW/1000 rpm and Weight: 8,000 kg, per ru.scribd.com.)
Dominant mechanical press designs
Mechanical dewatering via screw press is the dominant approach because EFB is bulky and heterogeneous. Other methods—batch hydraulic or piston presses, belt filters, centrifuges—are uncommon for EFB. A high-pressure hydraulic/piston press could achieve similar moisture removal, but at higher capital cost and cycling time, and belt/vacuum filters are common for sludge treatment but not practical for EFB. In short, the modern palm mill standard is a screw press or shredder+press line (www.simecpellet.com).
Throughput is matched to fiber reality: machines quoted at 6–12 t/h produce loose bunches of 4–6 inch fibers at the stated rates (news.kharisma-sawit.com).
Electrical energy use and baselines
Typical palm-mill screw presses draw on the order of 4–8 kWh per tonne of fresh EFB (kWh/t), a small electrical load relative to thermal drying. A 12 t/h press with a 45 kW motor lands around ~3.8 kWh/t, while a 75 kW unit at ~10–12 t/h runs ~6–7.5 kWh/t (www.simecpellet.com; ru.scribd.com). Cylindrical screw presses across biomass materials span roughly 12 to 60 kWh/t (ancalc.com), which covers the palm case.
In L/day terms, a 45 kW press running 20 hours/day uses ~900 kWh/day (for 12 t × 20 h ≈240 t), i.e. ≈3.75 kWh/t; a larger 75 kW press at 12 t/h (~20 h/d) uses ~1,500 kWh/d (~6.25 kWh/t). By comparison, vacuum belt or thermal dryers used for further moisture reduction consume tens of kWh/t or more, so mechanical dewatering remains efficient. In summary, electrical energy per tonne of EFB pressed is typically ~5–10 kWh, or less—about $0.5–1.0 per tonne at ~$0.1/kWh (www.simecpellet.com; ancalc.com).
Dewatered fiber quality metrics
The headline metric is moisture content, on a wet basis (w.b., measured as water mass divided by total mass). Presses typically reduce EFB from ~70% moisture down to ~45–55% (www.simecpellet.com; ru.scribd.com). Fresh EFB out of the mill registers ~65–75% moisture (hoongchan.com), and Indonesian sources confirm ~50–55% after the press, with machine-dependent variation (hoongchan.com; news.kharisma-sawit.com).
The solid “cake” is coarse and springy; fiber chunks (≈3–8″) fall apart easily by hand. Residual moisture is still high enough that piled fiber can re-wet quickly; field measurements show shredded EFB rising from ~50% to 60–65% moisture after piling in hot climates due to microbial respiration (hoongchan.com), prompting mills to vent or cool fiber stores.
Because pressed EFB remains ~50% water, mills either use it immediately as boiler fuel or move it into low-grade pellet production. Higher-value pellet or pulp applications need further drying—often via integrated disc or belt dryers—to ~10–15% moisture, since most pellet plants require low feed MC (hoongchan.com). Even so, compared with unpressed EFB, the ~50% MC fiber is far more usable; it can be stored, burned, or handled without turning into slurry.
Oil recovery in press liquor
The squeezed liquor carries tiny amounts of oil—typically 0.1–0.3% of the fresh EFB weight—which mills recover via the existing clarification system (www.simecpellet.com; ru.scribd.com). Many plants route this stream through a clarifier; analogous equipment includes a clarifier in the oil-recovery train.
In practice, most remnant oil in EFB can be reclaimed. Malaysian professors report “standard oil losses from EFB are 4–6%” (of the fruit bunch) but pressed fibers contain less than 2% oil (ru.scribd.com), meaning most (~0.1–0.3% of fiber weight) flows out in the liquid. The captured oil heads to the refinery—often blended with decanter oil—boosting mill yield (www.simecpellet.com). Where needed, an oil removal step can be part of that recovery and polishing flow.
Energy and mass balances
Pressing removes roughly 0.20–0.25 tonne of water per tonne of fresh EFB (e.g., from ~70% down to ~50% moisture). Evaporating 0.25 t H₂O requires ~565 kWh (≈2.03 MJ/kg latent heat). By contrast, the press may use only ~5 kWh/t. The result: net savings of ~560 kWh (thermal) per tonne of EFB for each ~5 kWh (electric) consumed (ancalc.com).
Converted to fuel terms, ~560 kWh is 2.0 GJ (roughly 0.5 boiler‑gallon equivalent fuel). In other words, every 1 kWh of electricity yields ~112 kWh of heat content retained. Mills simultaneously recover ~2–3 kg of oil per tonne of EFB (at 0.2–0.3% oil extraction rate), per manufacturer and field data (www.simecpellet.com; ru.scribd.com).
Economics and payback
Capital outlay for a 10–12 t/h screw-press skid, including feeder/shredder where required, sits on the order of $50,000–$100,000 in Asia. Installation and design can add another ~20–30%. By contrast, building an anaerobic POME plant or buying fuel carries far higher CAPEX.
Operating cost is dominated by electricity. At ~5–8 kWh/t and industrial tariffs of ~$0.05–$0.10/kWh (Indonesia), power adds roughly $0.3–$0.8 per tonne of wet EFB. Pressing 96,000 t/yr would draw ~480,000 kWh, or about $24,000–$48,000 per year in power.
Benefits stack quickly. For each tonne of EFB processed, ~0.2 t less water must be boiled off; at ~2.2 MJ/kg, that’s ~45,000 MJ (12,500 kWh) retained in the fuel stream. With boiler efficiency factored, this can displace ~10–12 GJ of fuel per tonne, worth ~$60–$120/t at $6–$10/GJ—even after subtracting ~$0.5–$1/t for electricity. Oil recovery adds ~$1.20–$2.10 per tonne EFB at crude palm oil of ~$600–$700/t (~$0.30–$0.60 per tonne FFB) (www.simecpellet.com; ru.scribd.com).
A representative 12 t/h press at 8,000 h/yr (~96,000 t/yr) illustrates the net: electricity ≈ 6 kWh/t × 96,000 t = 576,000 kWh (say $30k at $0.05/kWh); oil recovery ≈ 0.25% × 96,000 t = 240 t (~$144k); fuel saved ≈ 96,000 t × 0.2 t H₂O/t × 2.2 MJ/kg ≈ 42,240 GJ (≈ 11,733 MWh)—at $8/GJ ≈ $338k. Even if only half the thermal energy is monetized (e.g., fiber displaces some coal), benefits far exceed the ~$30k electricity bill; the net gain could approach ~$450k/yr versus $30–50k in costs, implying payback well under two years.
Field experience aligns with the physics: latent heat saved per tonne of EFB (~120–125 kWh) is an order of magnitude above the ~5–10 kWh electricity input (www.simecpellet.com; ancalc.com)—a ratio that typically produces 1–3 year paybacks.
Secondary benefits and operations
Beyond the spreadsheet gains, dewatering reduces waste burdens and supports sustainability targets. Drier EFB burns cleaner—less visible smoke, less boiler scaling—and compressed fiber is easier to handle and store.
Methodology note: This analysis draws on equipment specifications, Indonesian industry information (e.g., Kharismapratama) and academic references. Key data include capacities and moisture reduction (news.kharisma-sawit.com; www.simecpellet.com), motor power ratings (www.simecpellet.com; ru.scribd.com), oil yields (www.simecpellet.com; ru.scribd.com), and generalized energy ranges for biomass presses (ancalc.com). Published EFB composition context appears in (www.sciencedirect.com). Indonesian industry information was incorporated where possible (e.g., Kharismapratama).
