Methanol is an essential intermediate chemical for formaldehyde, dimethyl-ether, methyl tertiary butyl ether, and other industries. It also has excellent combustion properties, although the energy density is only about half of gasoline. Recently, Indonesia’s methanol demand has been about 1.6 million tons annually, which import scheme dominates up to 80% while a natural-gas-based plant supplies the remaining. Besides raw material depletion, it is less environmentally friendly as CO2 emission upon production and utilization.

This design proposes a bio-methanol plant based on syngas from palm kernel shell gasification at an annual capacity of 100,000 tons in the Medan Industrial Area to accomplish about 11.75% of domestic demand. Recently, Northern Sumatra produced up to 1.40 million tons/year of palm kernel shell, which is a small portion of the product utilization as boiler fuel. This area provides water and power facilities. Land and sea transportations are also available to shift the raw materials and distribute the products.

Every kilogram of bio-methanol needs 1.60 kg of palm kernel shell as raw material. In addition, 1.10 kg of palm kernel shell should be provided for steam generation. It is equivalent to 270,000 tons per year which is available in the area. Gasifying agents also need 0.024 Nm3 of oxygen and 1.28 kg of steam for every kilogram of bio-methanol. Syngas generated in a five-parallel gasifier reactor should be reconditioned in a CO2 absorber column to the stoichiometric number of 1.85 before using as a reactant in a bio-methanol synthesis reactor. A fixed bed multi-tube reactor is operated at 100 bar and 250°C using CuO/ZnO/Al2O3 catalyst to convert the feed into bio-methanol. After reactor-outlet purification using distillation, the product composition achieves 99.89% bio-methanol.

In addition, the specific consumption of cooling, fresh boiler feed, and domestic water is 0.024 m3. It needs 2.18 kg superheated steam at 29 bar and 232°C to produce one kilogram of bio-methanol for reactant and heating. Specific compressed air of 8.211 Nm3 for the operating control system should be prepared. The plant is powered with 0.753 kWh/kg bio-methanol electricity from the national grid company. A 4 x 3 MW diesel genset should be installed for backing up, which needs fuel oil of 7.73 L/ton of product. The plant should run at 1.6224 man-hours per ton of product.

The proposed plant generates liquid waste containing 0.018 kg of BOD, 0.024 kg of COD, and 0.005 kg of Total Dissolved Solids for every ton of product. A small portion, equivalent to 940 tons annually of bio-methanol, is wasted. It is also identified that the plant emits 0.82 tons of CO2 per ton of product. It is expected that 90% of CO2 emissions will be captured and sold with 99.9% CO2 purity in the gas phase. Thus, the net CO2 emission is about 0.0818 ton/ton product and is considered CO2-neutral because generated from non-fossil resources. The solid waste as 0.0496 kg ash/kg product of gasification operations is a potential raw material for light brick industries. This plant also considers a 30% of Mono Ethanol Amine solution for absorbing carbon dioxide. It needs about 19.65 kg of the solution for a kilogram of bio-methanol product, but this could be recycled after utilization.

The economic evaluation shows that this plant needs capital and operating expenditures of about USD 32.0 million and USD 63.0 million, respectively. The effort to convert palm kernel shells into bio-methanol is commercially feasible at a main product price of USD 400/ton and a side product price of USD 350/ton. Using ten years of economic lifetime, the plant generates a Net Present Value of USD 7.5 million, a Discounted Payback Period of 5.5 years, a Return on Investment of 26.89%, a Break Even Point of 54,51% of production capacity and an Internal Rate of Return of 15.29%.

The bio-methanol is flammable with a flash point at 11°C. It causes a mild skin irritant and eye irritation if contact occurs. Inhalation of bio-methanol and MEA vapor might cause drowsiness and dizziness. Proper handling and storage of bio-methanol and MEA are crucial to ensure the safety of employees and the environment. Therefore, bio-methanol and MEA must be stored in a well-ventilated area away from ignition sources. Moreover, the plant design considers personal protective equipment, first aid, and fire extinguishers with potential fire explosions at plant points.

The explosion of the gasification and synthesis bio-methanol reactor possibly occurs due to high temperature and pressure conditions. Installing a pressure-relieved valve to release the offset pressure back to its normal might reduce the probability of an accident. In addition, Temperature indicators and alarms are installed to monitor equipment temperature and provide a warning if the temperature exceeds standard limits so that precautions can be taken to prevent an explosion.