Europe’s largest olive cake boiler (11 MW) is working at full capacity

A Spanish manufacturer supplied a turnkey biomass steam boiler (Eckrohrkessel design) to Europe’s largest olive oil producer, which is now working at 8.000 h/y. The biomass boiler, with an equivalent thermal power of 11 MW (15 t/h) from the by-product of the plant itself, the olive cake, as fuel for the generation of process steam, is fitted at the San Miguel Arcángel factory in the city of Jaen in southern Spain.

As known, olive cake presents problems related to its ash content and its low melting point, so a specific design of an industrial multi-pass water-tube steam boiler has been developed to counteract the effect of fouling on the heat exchange body.

Alongside the heater, the manufacturer supplied other components for the complete installation of the plant, including the combustion system with a pusher step grate, the control system and the smoke treatment system to guarantee the quality of emissions in the atmosphere. San Miguel Arcángel is the largest olive marc producer in Europe.

Completed projects and research reports available


✔ Combustion study for roadside grass (untreated vs. pretreated, feasibility)
✔ Combustion study for almond shells
✔ Combustion study for bran
✔ Combustion study for low quality tropical wood
✔ Combustion study for rice husk
✔ Combustion study for maize straw pellets
✔ Combustion study for plant co-firing 70/30 – 80/20 olive residues
✔ Combustion study for SRF to limit corrosion risk
✔ Combustion study for US wood pellets
✔ Combustion study for mixed agro pellets (prunings, straw, corn stover)
✔ Combustion study for wood waste samples (troubleshooting)
✔ Combustion study for driftwood, raw vs. rain leached
✔ Combustion study for baltic wood mixtures (plant design)
✔ Project to identify factors impacting the biomass inorganic fraction variability
✔ Combustion feasibility study for a set of agricultural solid fuels
✔ Combustion study for different RDF samples (troubleshooting)
✔ Combustion study comparing mediterranean shrubs with pine pellets
✔ Combustion study for lignin rich, biorefinery waste residues
✔ Combustion study for sugarcane industry residues
✔ Combustion study for SRF char
✔ Combustion study for river maintenance wood
✔ Combustion study for palm oil processing residues
✔ Combustion feasibility study for flint corn
✔ Combustion study for beer industry waste
✔ Combustion study study for high-P pellets
✔ Combustion study for wine industry residues: chips and pellets
✔ Combustion study for spent coffee grounds
✔ Combustion study for different samples of corn cobs and coffee grounds
✔ Combustion study for olive residues biomass
✔ Project on torrefaction of biomass: ash slagging, fouling and corrosion
✔ Combustion study for king grass – sawdust blends
✔ Combustion feasibility study for available non-conventional woody fuels
✔ Combustion study for different fractions of RDF
✔ Gasification feasibility study for bamboo biomass



✔ Rapid laboratory method for prediction of slag formation in biomass combustion – beyond the Ash Fusion Test.
✔ Best available technologies for mitigating high temperature corrosion in biowaste to energy boilers.
✔ Best available technologies for mitigating ash slagging, agglomeration and fouling in biowaste to energy boilers.
✔ Review of mineral additives, catalysts, sorbents and active bed materials for mitigating ash related issues in biowaste combustion.
✔ Impact of fuel pre-treatment on ash related issues in combustion: torrefaction, steam explosion, hydrothermal carbonization and washing.
✔ Review of biomass and waste ash valorization: utilizations, opportunities and challenges.
✔ Return on experiences of biomass thermal utilization in cement kilns, glass and metallurgical industries.
✔ Review of biomass ash related challenges in oxyfuel, CLC and gasification.
✔ Biomass ash related challenges in SRF, RDF and MSW combustion: a state-of-the-art review.
✔ Asian available non conventional biomass fuels: predicting ash related issues.
✔ Analysis of origin of inorganic elements in biomass with case studies of process contaminations.
✔ Recommendations for reliable and representative fuel characterization based on industrial return on experience.
✔ Biomass combustion CFD simulations: state-of-the-art literature review.



✔ Fouling propensity of high-phosphorus solid fuels: Predictive criteria and ash deposits characterisation of sunflower hulls with P/Ca-additives in a drop tube furnace, Fuel 170, 16-26.
✔ A modelling approach for the assessment of an air-dryer economic feasibility for small-scale biomass steam boilers, Fuel Processing Technology 134, 251-258.
✔ Ash Characterization of Four Residual Wood Fuels in a 100 kWth Circulating Fluidized Bed Reactor Including the Use of Kaolin and Halloysite Additives, Energy & Fuels 30 (10), 8304-8315.
✔ A thermochemical approach based on phase diagrams to characterize biomass ash and select the optimal thermal conversion technology, 6th International Symposium on Energy from Biomass and Waste.
✔ Development of a tool to predict biomass fuels agglomeration and slagging propensity in combustion applications, Proceedings of the 23rd European Biomass Conference and Exhibition, 1782-1786.
✔ Assessment of ash agglomeration and fouling in combustion by theoretical and experimental biomass fuels characterization, PhD Thesis.
✔ Advanced characterization of available not conventional mediterranean biomass solid fuels for ash related issues in thermal processes, Chemical Engineering Transactions 50.
✔ Characterization of sunflower husks fouling in a Drop Tube Furnace: comparison of deposits with H3PO4, CaCO3 and Al2Si2O5(OH)4 additives, Proceedings of the 24th European Biomass Conference and Exhibition, 748-755.

Sludge, slurries combustion and inorganics: a state of the art literature collection

Dirbeba, M.J., Brink, A., Lindberg, D., Hupa, M., Hupa, L., 2021. Thermal Conversion Characteristics of Molasses. ACS Omega 6, 21631–21645.

Guo, S., Gao, J., Zhao, D., Zhao, C., Li, X., Li, G., 2022. Co-combustion of sewage sludge and Zhundong coal: Effects of combustion conditions on gaseous pollutant emission and ash properties. Sustainable Energy Technologies and Assessments 54, 102836.

Ma, M., Liang, Y., Xu, D., Sun, S., Zhao, J., Wang, S., 2022. Gas emission characteristics of sewage sludge co-combustion with coal: Effect of oxygen atmosphere and feedstock mixing ratio. Fuel 322, 124102.

Manwatkar, P., Dhote, L., Pandey, R.A., Middey, A., Kumar, S., 2021. Combustion of distillery sludge mixed with coal in a drop tube furnace and emission characteristics. Energy 221, 119871.

Romanov, D.S., Vershinina, K.Yu., Dorokhov, V.V., Strizhak, P.A., 2022. Rheology, ignition, and combustion performance of coal-water slurries: Influence of sequence and methods of mixing. Fuel 322, 124294.

Strandberg, A., Skoglund, N., Thyrel, M., 2021. Morphological characterisation of ash particles from co-combustion of sewage sludge and wheat straw with X-ray microtomography. Waste Management 135, 30–39.

Wang, T., Lou, Y., Jiang, S., Wang, J., Zhang, Y., Pan, W.-P., 2022. Distribution characteristics and environmental risk assessment of trace elements in desulfurization sludge from coal-fired power plants. Fuel 314, 122771.

Wang, Y., Jia, L., Guo, B., Wang, B., Zhang, L., Zheng, X., Xiang, J., Jin, Y., 2022. Effects of CaO-Fe2O3-Fe3(PO4)2 in sewage sludge on combustion characteristics and kinetics of coal slime. Fuel 322, 124267.

Zhang, D., Ma, T., 2022. Study on slagging in a waste-heat recovery boiler associated with a bottom-blown metal smelting furnace. Energy 241, 122852.

Zheng, L., Jin, J., Liu, Z., Kou, X., He, X., Shen, L., 2022. Ash formation characteristics in co-combusting coagulation sludge and Zhundong coal. Fuel 311, 122571.

Zhou, A., Ma, W., Ruan, R., Li, Y., Zhang, Q., Mao, R., Yu, S., Deng, S., Tan, H., Wang, X., 2022a. Experimental study on PM10 formation characteristics of co-combustion with pulverized coal and sludge. Fuel Processing Technology 236, 107438.

Zhou, A., Wang, X., Magdziarz, A., Yu, S., Deng, S., Bai, J., Zhang, Q., Tan, H., 2022b. Ash fusion and mineral evolution during the co-firing of coal and municipal sewage sludge in power plants. Fuel 310, 122416.

Scaling up biomass: focus on Southeast Asia



As one of the fastest growing regions in the world in terms of gross domestic product
(GDP), population, and demand for both food and energy, Southeast Asia has a strong
need to decarbonise its economies and modernise its energy systems. In 2018, around 75%
of primary energy demand in the region was met by fossil fuels such as oil, coal and gas.
Many key economic activities depend on fossil fuels for heat, which makes substitution
with established forms of renewable energy such as hydro, solar or wind challenging.
Bioenergy is the most versatile form of renewable energy derived from forestry and
agricultural products including residues and wastes.
IRENA’s Global Renewables Outlook: Energy Transformation 2050 (IRENA, 2020a)
reported that bioenergy could become the largest energy source in the total energy
mix in Southeast Asia, accounting for over 40% of total primary energy supply (TPES)
in 2050 under its Transforming Energy Scenario (TES), which is consistent with the Paris
Agreement’s goal of restricting global temperature rises to well below 2°C. In this scenario,
the majority of the biomass would be used in the industry (40% of total bioenergy supply)
and transport sectors (37% of total bioenergy supply).
This report investigates the potential for bioenergy to economically replace a portion
of fossil fuel use in the energy markets of five Southeast Asian countries. It outlines
the need for a robust bioenergy transformation plan to reduce dependency on fossil
fuels, strengthen national resilience and enhance energy security. The key barriers and
interventions identified in this study may therefore serve as a guide for the policy actions
required to develop such a plan.