盐碱滩上建起绿色甲醇工厂 天津芦竹基项目加速推进A green methanol plant has been built on the saline-alkali beach, and the Tianjin Luzhuji project is accelerating.

The 100,000-ton-per-year green methanol project based on reed bamboo, located in the Dagang Petrochemical Industrial Park of Tianjin Binhai New Area, is accelerating construction. As the final part of the first-phase closed-loop project of the Tianjin Ruihengmao Group New Energy and New Materials Industrial Base, the project has entered the final stage, with plans for the second phase being laid out simultaneously. After completion, the base is expected to have an annual output value of 5 billion yuan and reduce carbon dioxide emissions by 2.4 million tons per year.

The raw material comes from a plant growing on the saline-alkali tidal flats in Binhai. At the edge of the Bohai Sea, the Beidagang Wetland receives purified municipal sewage, becoming an important source of ecological water replenishment; municipal sludge and livestock manure that were once difficult to dispose of on the tidal flats are treated harmlessly and return to the land as fertile soil; along both sides of the river, reed bamboo takes root and grows, stretching out in large patches. A full-chain closed loop of 'water, fertilizer, soil, bamboo, fiber, alcohol, carbon' is reconnected on this land.

Turning wild grass into a 'standard component' relies on variety breeding. At the Luzhu Seed Industry Innovation Base in Xiaozhan Town, Jinnan District, Tianjin, seedlings in the greenhouses grow uniformly. Ruihengmao's bred polyploid luzhu variety 'Lvzhou No. 1' can grow on saline-alkali soil with a salt content of 6‰, withstand temperatures as low as minus 20 degrees Celsius, and can be continuously harvested for 20 years from a single planting; during its high-yield period, it produces over 4 tons of dry matter per acre annually, with a calorific value of 3900 to 4400 kcal/kg, and a total cellulose, hemicellulose, and lignin content exceeding 86%. Wang Jinshan, chief engineer of Luzhu planting at Ruihengmao Group, stated that since tidal flats, wetlands, and saline-alkali lands are widely distributed in Tianjin, luzhu’s pollution resistance, salt-alkali tolerance, metal stress resistance, and nitrogen-fixing effect of its roots make it suitable for soil improvement planting, aligning with the local ecological environment and industrial structure.

A seedling breeding system is being built concurrently. The team is advancing technical research on plant polyploid mutation, gene sequencing, and other areas, selecting and cultivating new varieties suited for energy, materials, feed, and other purposes. On the breeding side, relying on technologies such as one-time tissue culture rapid propagation, open-type tissue culture rapid propagation, and mother plant virus-free rejuvenation and multiplication, a standardized seedling breeding system has been established. According to the plan, by 2026, the annual production capacity of Arundinaria seedlings will reach 200 million plants, meeting the planting demand for 200,000 mu. Each mu of Arundinaria can sequester 5 to 8 tons of carbon. In the first phase, 80,000 mu of saline-alkali land will be improved to plant Arundinaria, and in the second phase, an additional 120,000 mu will be added, turning marginal land into a raw material base with sustainable output.

The difficulty in producing green methanol lies not in 'methanol' itself, but in 'green'. The project proposes the 'Three Zeros Project' goals, namely zero use of fossil energy, zero consumption of fresh water, and zero emissions of organic solid waste, liquid waste, and harmful gases. The process adopts a pressurized oxygen biomass gasification route for synthesizing green methanol. Bamboo is gasified under pressurized oxygen to produce syngas, about 30% of which is sent to a gas turbine to generate power. The high-temperature flue gas then enters a waste heat boiler to produce high-pressure steam, which is returned to the gasification section for use. The remaining approximately 70% of the syngas is used to synthesize methanol, achieving cascade utilization of energy, and the overall system carbon conversion rate reaches over 98%. Lin Hongxin, Chairman of Ruihengmao Group, introduced the above process arrangement.

Water and solid waste are equally integrated into a closed loop. In 2012, Ruihengmao pioneered the smart water management solution, expanding sewage treatment from a two-step process of 'treatment—discharge' to a six- to eight-cycle process of 'treatment—regeneration—reuse—treatment—toward zero—low discharge.' By 2025, the group will implement photovoltaic upgrades at its municipal sewage treatment plants, industrial sewage treatment plants, and reclaimed water plants, reducing energy consumption per ton of treated water by 10% year-on-year, achieving the best level since the plants were built. The three water plants provide stable water supply and sewage disposal for the methanol project. The company independently developed a five-stage dual-system negative-carbon treatment and disposal technology for municipal sludge, converting sludge into saline-alkali soil conditioners and specialized fertilizer for reed bamboo, capable of processing 500,000 tons of sludge generated annually by Tianjin sewage treatment plants. The waste residue from methanol production is reused for fertilizer production. It is estimated that the project can directly reduce more than 300,000 tons of carbon dioxide annually and has received the 2025 Hydrogen-Based Industry Carbon Neutrality Award and the National Most Investment-Worthy Huayao Award.

The products target multiple carbon reduction scenarios. Green methanol can be directly used as fuel for vehicles and ships, or transformed to produce new chemical materials; green fibers and sustainable aviation fuel address the carbon reduction needs of the textile and civil aviation sectors, respectively. Relevant project cases have been included in major environmental protection initiatives in the Beijing-Tianjin-Hebei region, and the industry and technology pathways have been recognized by the Ministry of Ecology and Environment and listed in its major project guidance catalog. According to the plan, after both phases of the project are completed, the total investment in the base will reach 5.8 billion yuan, with an expected annual output value of 5 billion yuan, tax revenue of 390 million yuan, employment for more than 2,000 people, and an annual reduction of 2.4 million tons of carbon dioxide emissions. Ruihengmao plans to expand and replicate the project in eight provinces and cities by 2035: Tianjin, Hebei, Henan, Shandong, Anhui, Jiangsu, Hubei, and Shanghai.

[Source: Science and Technology Daily]

[Editor: Xiao Neng]