The main product of solid biomass gasification is a renewable gas known as synthesis gas or syngas. Gasification is a thermochemical process different from the biological process that results in biogas, the best-known renewable gas, although their applications are similar: from the generation of heat and/or electricity to their use in the chemical industry and even, upgrading for grid injection.
One of the advantages of gasification is that it can process a wide variety of solid biomass: agricultural biomass such as pruning waste, bagasse, olive pits, pomace, husks or straw; forest biomass in the form of wood chips or pellets; demolition wood; sewage sludge, meat meals or poultry waste, and even fuels recovered from waste (FSR) or the organic fraction of municipal solid waste (OFMSW).
Gasification is not yet implemented in our country as it already is in other countries in Europe and the world. To date, only 7 industrial plants and 2 pilot or demonstration plants are in operation.. It does not yet have a roadmap for its development, as biogas or hydrogen already do, but its potential in Spain is estimated to be really significant, even greater than that of biogas, according to a study by Sedigas this year.
Technologists agree: the technology has been viable for some time, but potential users lacked information. The 2030 Agenda and increasingly widespread and understood concepts such as circularity, self-sufficiency, and the production of high value-added products are creating the context for the promotion of exciting projects in the coming years.
A roadmap for solid biomass gasification is essential
In Spain, the potential of gasification and objectives for its inclusion in the energy mix have not been defined, but the IDAE (Institute for Energy Diversification and Saving) and the PER (Regional Energy Plan) estimate that the agricultural and forestry waste generated by the country could contribute more than 10,000 ktoe/year of energy. PNIEC It sets an annual target of 3,000 ktoe from these by-products until 2030, of which 2,000 ktoe will be used to generate bioelectricity and bioheat.
Part of this energy generation could be achieved through gasification. This technology offers several advantages over biomass valorization by combustion, as it utilizes all the resulting fractions while reducing net emissions: the gaseous fraction, or syngas, for energy generation; the solid fraction, or biochar, for agricultural or environmental uses (carbon sequestration); and the liquid fraction for the chemical industry.
Several companies in Spain, many associated with AVEBIOM, offer their own solutions and technologies for gasification, torrefaction, carbonization or pyrolysis of solid biomass for different applications and under different business models that guarantee economic profitability and an improvement in the environmental performance of their clients.
Some of the most prominent Spanish companies capable of implementing gasification projects are Aresol, Bioliza, Van Mander, Waste to Energy Advanced Solutions, INERCO, Green_E (pyrolysis), Ingelia (hydrothermal carbonization), Yilkins (torrefaction).
What gasification technologies do plants in Spain use?
The gasification plants installed in Spain use different gasifiers: downdraft, updraft or of bubbling fluidized bed.
In general, gasifiers bubbling fluidized bed They have the advantage of greater flexibility in terms of the quality of biomass they can process, as well as greater efficiency in converting biomass to gas. However, their design and operation can be more complex and expensive than those of reactors. downdraft o updraft.
Downdraft gasification
Bioliza has used technology downdraft of gasification to valorize pomace at the Aceites Guadalentín plant, in Pozo Alcón, Jaén.
This technology is the simplest for small power outputs; it gasifies with air and requires material with a maximum moisture content of 20% and a homogeneous particle size. It guarantees superior efficiency compared to 70% in production of syngas, which increases to 90% if the biochar obtained.
This syngas It has a calorific value of 1,300 kcal/Nm3 (5.4 MJ/Mm3), although the air can be enriched with O2 to increase this value, and is used in cogeneration engines, once it is clean of moisture and tars.
José Antonio La Cal, founder of Bioliza, explains that “Downdraft gasification fits well into circular economy models at power levels of 15-20 MWt (4-5 MWe) for self-consumption and can be implemented in industries with a high demand for thermal and electrical energy: cement plants, brick factories, olive pomace mills, plasterboard factories, agri-food, etc.”
Gasification in bubbling fluidized bed reactors
Waste to Energy Advanced Solutions (WtE) has developed its own technology based on bubbling fluidized bed gasification, “with the aim of helping companies reduce their environmental impact”, "explains its CEO, Andrés Ponce.".
Its technology is used in five plants: three in Spain (Salamanca, Ejea de los Caballeros and Xátiva), one in Portugal and one in Switzerland.
In Salamanca, a 10 MWt plant gasifies 10,000 t/year of meat meal to generate syngas which replaces natural gas to generate process steam used by the industry itself, a good example of a circular economy. In Xàtiva, a ceramics factory has a 1.6 MW wood chip gasification plant for cogeneration; the electricity is fed into the grid and the remaining heat and the biochar are used in the briquette manufacturing for drying the starting biomass and improving the final calorific value.
They operate at power outputs from 5 to 50 MWt (lower outputs compromise economic viability). They gasify with atmospheric air in a robust, high-performance, and easy-to-operate reactor that can handle a wide variety of biomass, including waste.
INERCO It also offers a bubbling fluidized bed solution to treat everything from biomass such as wood pellets and chips or energy crops to olive pits, pomace, sewage sludge or straw.
Two experimental plants utilize their technology: a 3 MWt plant at the CIUDEN experimental center in Ponferrada, León, which aims to demonstrate the technology using a mixture of air with CO2 and O2 as the gasifying agent and wood pellets and chips as feedstock. The second plant is located at CENER in Pamplona; it has a capacity of 2 MWt and is designed to gasify wood chips, wood pellets, and straw using air or a mixture of air, steam, and O2.
Pedro Rodríguez, Director of Engineering at INERCO, clarifies that “A gasification plant is not a washing machine where you put anything in and get a valuable product; each plant must be specified for a certain type of biomass in order to operate optimally.”.
Gasification updraft and torsional camera
Engineering ARESOL It manages two gasification plants, one with WtE bubbling fluidized bed technology in Ejea de los Caballeros, Zaragoza, where they are carrying out improvements after its acquisition; and another in Gesuga, A Coruña, where meat meals are valorized to produce process steam and self-consumption in a facility that consists of a gasifier with technology updraft to generate the syngas, a torsional combustion chamber, a steam boiler and an exhaust gas treatment system with a bag filter.
Gustavo Carbajo, head of the Gasification department, is clear that it is time to develop new projects: “We have the technology; now it is up to the administration to facilitate it: it is essential.”.
Pyrolysis
GREEN_e It has developed its own pyrolysis technology to valorize waste by maximizing the liquid fraction in the form of oil for the petrochemical industry. The process also yields a solid fraction, char, and gases that are used to generate energy for the pyrolysis process.
They already have five plant projects underway, each capable of processing 40,000 tons of waste per year. These plants are located throughout Spain: in the Basque Country, Zaragoza, Galicia, and Alicante, with the first one scheduled to begin operations at the end of 2024.
Santiago Viórquez, head of the Process department, assures that their technology “"It allows for the valorization of a wide variety of waste, even if it contains plastics, to obtain high-quality products.". The customer profile is found in industries such as agri-food, paper, meat, brewing or among waste managers.
Other plants
The Neoelectra plant in Villacañas, The plant in Toledo has a capacity of 7.8 MWt and gasifies sawmill and forestry byproducts in a facility with a gasifier and torsional chamber. Movialsa in Ciudad Real It has 6 MWe and carbonates grape and olive pomace. In Murcia, the CEDER-Ciemat has developed a 200 kWt sewage sludge gasification plant.
PUBLISHED in Biomass News No. 7 – April 2023
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